Merge branch 'master' into pr/949-yasser-handler-mapping

annotations/annotation-processing/pom.xml

@@ -15,7 +15,7 @@
 
     <properties>
         <auto-service.version>1.0-rc2</auto-service.version>
-        <maven-compiler-plugin.version>3.5.1</maven-compiler-plugin.version>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
     </properties>
 
     <dependencies>

annotations/annotation-user/pom.xml

@@ -13,6 +13,11 @@
 
     <artifactId>annotation-user</artifactId>
 
+    <properties>
+        <junit.version>4.12</junit.version>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>        
+    </properties>
+    
     <dependencies>
 
         <dependency>
@@ -24,7 +29,7 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
 
@@ -37,7 +42,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.5.1</version>
+                <version>${maven-compiler-plugin.version}</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>

apache-cxf/README.md

@@ -0,0 +1,2 @@
+## Relevant Articles:
+- [Introduction to Apache CXF Aegis Data Binding](http://www.baeldung.com/aegis-data-binding-in-apache-cxf)

apache-cxf/cxf-aegis/pom.xml

@@ -0,0 +1,20 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>cxf-aegis</artifactId>
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>apache-cxf</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    <properties>
+        <cxf.version>3.1.8</cxf.version>        
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.cxf</groupId>
+            <artifactId>cxf-rt-databinding-aegis</artifactId>
+            <version>${cxf.version}</version>
+        </dependency>
+    </dependencies>
+</project>

apache-cxf/cxf-aegis/src/main/java/com/baeldung/cxf/aegis/Course.java

@@ -0,0 +1,42 @@
+package com.baeldung.cxf.aegis;
+
+import java.util.Date;
+
+public class Course {
+    private int id;
+    private String name;
+    private String instructor;
+    private Date enrolmentDate;
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getInstructor() {
+        return instructor;
+    }
+
+    public void setInstructor(String instructor) {
+        this.instructor = instructor;
+    }
+
+    public Date getEnrolmentDate() {
+        return enrolmentDate;
+    }
+
+    public void setEnrolmentDate(Date enrolmentDate) {
+        this.enrolmentDate = enrolmentDate;
+    }
+}

apache-cxf/cxf-aegis/src/main/java/com/baeldung/cxf/aegis/CourseRepo.java

@@ -0,0 +1,11 @@
+package com.baeldung.cxf.aegis;
+
+import java.util.Map;
+
+public interface CourseRepo {
+    String getGreeting();
+    void setGreeting(String greeting);
+    Map<Integer, Course> getCourses();
+    void setCourses(Map<Integer, Course> courses);
+    void addCourse(Course course);  
+}

apache-cxf/cxf-aegis/src/main/java/com/baeldung/cxf/aegis/CourseRepoImpl.java

@@ -0,0 +1,34 @@
+package com.baeldung.cxf.aegis;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class CourseRepoImpl implements CourseRepo {
+    private String greeting;
+    private Map<Integer, Course> courses = new HashMap<>();
+
+    @Override
+    public String getGreeting() {
+        return greeting;
+    }
+
+    @Override
+    public void setGreeting(String greeting) {
+        this.greeting = greeting;
+    }
+
+    @Override
+    public Map<Integer, Course> getCourses() {
+        return courses;
+    }
+
+    @Override
+    public void setCourses(Map<Integer, Course> courses) {
+        this.courses = courses;
+    }
+
+    @Override
+    public void addCourse(Course course) {
+        courses.put(course.getId(), course);
+    }
+}

apache-cxf/cxf-aegis/src/main/resources/com/baeldung/cxf/aegis/Course.aegis.xml

@@ -0,0 +1,5 @@
+<mappings>
+    <mapping>
+        <property name="instructor" ignore="true"/>
+    </mapping>
+</mappings>

apache-cxf/cxf-aegis/src/main/resources/com/baeldung/cxf/aegis/CourseRepo.aegis.xml

@@ -0,0 +1,5 @@
+<mappings xmlns:ns="http://courserepo.baeldung.com">
+    <mapping name="ns:Baeldung">
+        <property name="greeting" style="attribute"/>
+    </mapping>
+</mappings>

apache-cxf/cxf-aegis/src/test/java/com/baeldung/cxf/aegis/BaeldungTest.java

@@ -0,0 +1,93 @@
+package com.baeldung.cxf.aegis;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import org.junit.Test;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.lang.reflect.Type;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import javax.xml.namespace.QName;
+import javax.xml.stream.XMLInputFactory;
+import javax.xml.stream.XMLOutputFactory;
+import javax.xml.stream.XMLStreamReader;
+import javax.xml.stream.XMLStreamWriter;
+
+import org.apache.cxf.aegis.AegisContext;
+import org.apache.cxf.aegis.AegisReader;
+import org.apache.cxf.aegis.AegisWriter;
+import org.apache.cxf.aegis.type.AegisType;
+
+public class BaeldungTest {
+    private AegisContext context;
+    private String fileName = "baeldung.xml";
+
+    @Test
+    public void whenMarshalingAndUnmarshalingCourseRepo_thenCorrect() throws Exception {
+        initializeContext();
+        CourseRepo inputRepo = initCourseRepo();
+        marshalCourseRepo(inputRepo);
+        CourseRepo outputRepo = unmarshalCourseRepo();
+        Course restCourse = outputRepo.getCourses().get(1);
+        Course securityCourse = outputRepo.getCourses().get(2);
+        assertEquals("Welcome to Beldung!", outputRepo.getGreeting());
+        assertEquals("REST with Spring", restCourse.getName());
+        assertEquals(new Date(1234567890000L), restCourse.getEnrolmentDate());
+        assertNull(restCourse.getInstructor());
+        assertEquals("Learn Spring Security", securityCourse.getName());
+        assertEquals(new Date(1456789000000L), securityCourse.getEnrolmentDate());
+        assertNull(securityCourse.getInstructor());
+    }
+    
+    private void initializeContext() {
+        context = new AegisContext();
+        Set<Type> rootClasses = new HashSet<Type>();
+        rootClasses.add(CourseRepo.class);
+        context.setRootClasses(rootClasses);
+        Map<Class<?>, String> beanImplementationMap = new HashMap<>();
+        beanImplementationMap.put(CourseRepoImpl.class, "CourseRepo");
+        context.setBeanImplementationMap(beanImplementationMap);
+        context.setWriteXsiTypes(true);
+        context.initialize();
+    }
+    
+    private CourseRepoImpl initCourseRepo() {
+        Course restCourse = new Course();
+        restCourse.setId(1);
+        restCourse.setName("REST with Spring");
+        restCourse.setInstructor("Eugen");
+        restCourse.setEnrolmentDate(new Date(1234567890000L));
+        Course securityCourse = new Course();
+        securityCourse.setId(2);
+        securityCourse.setName("Learn Spring Security");
+        securityCourse.setInstructor("Eugen");
+        securityCourse.setEnrolmentDate(new Date(1456789000000L));
+        CourseRepoImpl courseRepo = new CourseRepoImpl();
+        courseRepo.setGreeting("Welcome to Beldung!");
+        courseRepo.addCourse(restCourse);
+        courseRepo.addCourse(securityCourse);
+        return courseRepo;
+    }
+    
+    private void marshalCourseRepo(CourseRepo courseRepo) throws Exception {
+        AegisWriter<XMLStreamWriter> writer = context.createXMLStreamWriter();
+        AegisType aegisType = context.getTypeMapping().getType(CourseRepo.class);
+        XMLStreamWriter xmlWriter = XMLOutputFactory.newInstance().createXMLStreamWriter(new FileOutputStream(fileName));
+        writer.write(courseRepo, new QName("http://aegis.cxf.baeldung.com", "baeldung"), false, xmlWriter, aegisType);
+        xmlWriter.close();
+    }
+
+    private CourseRepo unmarshalCourseRepo() throws Exception {       
+        AegisReader<XMLStreamReader> reader = context.createXMLStreamReader();
+        XMLStreamReader xmlReader = XMLInputFactory.newInstance().createXMLStreamReader(new FileInputStream(fileName));
+        CourseRepo courseRepo = (CourseRepo) reader.read(xmlReader, context.getTypeMapping().getType(CourseRepo.class));
+        xmlReader.close();
+        return courseRepo;
+    }
+}

apache-cxf/cxf-introduction/pom.xml

@@ -4,15 +4,18 @@
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>cxf-introduction</artifactId>
+    
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>apache-cxf</artifactId>
         <version>0.0.1-SNAPSHOT</version>
     </parent>
+    
     <properties>
-        <cxf.version>3.1.6</cxf.version>
+        <cxf.version>3.1.8</cxf.version>
         <surefire.version>2.19.1</surefire.version>        
     </properties>
+    
     <build>
         <plugins>
             <plugin>
@@ -24,7 +27,7 @@
             </plugin>
             <plugin>
                 <artifactId>maven-surefire-plugin</artifactId>
-                <version>2.19.1</version>
+                <version>${surefire.version}</version>
                 <configuration>
                     <excludes>
                         <exclude>**/*LiveTest.java</exclude>
@@ -33,6 +36,7 @@
             </plugin>
         </plugins>
     </build>
+    
     <dependencies>
         <dependency>
             <groupId>org.apache.cxf</groupId>

apache-cxf/cxf-jaxrs-implementation/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [Apache CXF Support for RESTful Web Services](http://www.baeldung.com/apache-cxf-rest-api)

apache-cxf/cxf-jaxrs-implementation/pom.xml

@@ -4,17 +4,20 @@
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>cxf-jaxrs-implementation</artifactId>
+    
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>apache-cxf</artifactId>
         <version>0.0.1-SNAPSHOT</version>
     </parent>
+    
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <cxf.version>3.1.7</cxf.version>
+        <cxf.version>3.1.8</cxf.version>
         <httpclient.version>4.5.2</httpclient.version>
         <surefire.version>2.19.1</surefire.version>        
     </properties>
+    
     <build>
         <plugins>
             <plugin>
@@ -26,7 +29,7 @@
             </plugin>
             <plugin>
                 <artifactId>maven-surefire-plugin</artifactId>
-                <version>2.19.1</version>
+                <version>${surefire.version}</version>
                 <configuration>
                     <excludes>
                         <exclude>**/*LiveTest.java</exclude>
@@ -35,6 +38,7 @@
             </plugin>
         </plugins>
     </build>
+    
     <dependencies>
         <dependency>
             <groupId>org.apache.cxf</groupId>

apache-cxf/cxf-spring/pom.xml

@@ -33,7 +33,7 @@
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>javax.servlet-api</artifactId>
-            <version>3.1.0</version>
+            <version>${javax.servlet-api.version}</version>
         </dependency>
     </dependencies>
     
@@ -41,7 +41,7 @@
         <plugins>
             <plugin>
                 <artifactId>maven-war-plugin</artifactId>
-                <version>2.6</version>
+                <version>${maven-war-plugin.version}</version>
                 <configuration>
                     <failOnMissingWebXml>false</failOnMissingWebXml>
                 </configuration>
@@ -66,7 +66,7 @@
                     <plugin>
                         <groupId>org.codehaus.cargo</groupId>
                         <artifactId>cargo-maven2-plugin</artifactId>
-                        <version>1.4.19</version>
+                        <version>${cargo-maven2-plugin.version}</version>
                         <configuration>
                             <container>
                                 <containerId>tomcat8x</containerId>
@@ -121,9 +121,13 @@
     </profiles>
     
     <properties>
-        <cxf.version>3.1.6</cxf.version>
-        <spring.version>4.3.1.RELEASE</spring.version>
+        <cxf.version>3.1.8</cxf.version>
+        <spring.version>4.3.4.RELEASE</spring.version>
+        <javax.servlet-api.version>3.1.0</javax.servlet-api.version>
+        
+        <maven-war-plugin.version>2.6</maven-war-plugin.version>        
         <surefire.version>2.19.1</surefire.version>
+        <cargo-maven2-plugin.version>1.6.1</cargo-maven2-plugin.version>        
     </properties>
     
 </project>

apache-cxf/pom.xml

@@ -5,19 +5,29 @@
     <artifactId>apache-cxf</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>pom</packaging>
+    
     <modules>
         <module>cxf-introduction</module>
         <module>cxf-spring</module>
         <module>cxf-jaxrs-implementation</module>
+        <module>cxf-aegis</module>
     </modules>
+    
+    <properties>
+        <junit.version>4.12</junit.version>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
+    </properties>
+    
     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
+    
     <build>
         <defaultGoal>install</defaultGoal>
         <pluginManagement>
@@ -25,7 +35,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.5.1</version>
+                    <version>${maven-compiler-plugin.version}</version>
                     <configuration>
                         <source>1.8</source>
                         <target>1.8</target>
@@ -34,7 +44,7 @@
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>exec-maven-plugin</artifactId>
-                    <version>1.5.0</version>
+                    <version>${exec-maven-plugin.version}</version>
                 </plugin>
             </plugins>
         </pluginManagement>

apache-fop/pom.xml

@@ -67,7 +67,7 @@
 		<dependency>
 			<groupId>org.apache.xmlgraphics</groupId>
 			<artifactId>fop</artifactId>
-			<version>1.1</version>
+			<version>${fop.version}</version>
 			<exclusions>
 				<exclusion>
 					<groupId>org.apache.avalon.framework</groupId>
@@ -83,18 +83,18 @@
 		<dependency>
 			<groupId>avalon-framework</groupId>
 			<artifactId>avalon-framework-api</artifactId>
-			<version>4.2.0</version>
+			<version>${avalon-framework.version}</version>
 		</dependency>
 		<dependency>
 			<groupId>avalon-framework</groupId>
 			<artifactId>avalon-framework-impl</artifactId>
-			<version>4.2.0</version>
+			<version>${avalon-framework.version}</version>
 		</dependency>
 
 		<dependency>
 			<groupId>org.dbdoclet</groupId>
 			<artifactId>dbdoclet</artifactId>
-			<version>8.0.2</version>
+			<version>${dbdoclet.version}</version>
 		</dependency>
 
 		<dependency>
@@ -108,7 +108,7 @@
 		<dependency>
 			<groupId>net.sf.jtidy</groupId>
 			<artifactId>jtidy</artifactId>
-			<version>r938</version>
+			<version>${jtidy.version}</version>
 		</dependency>
 
 	</dependencies>
@@ -187,40 +187,22 @@
     </profiles>
     
 	<properties>
-		<!-- persistence -->
-		<hibernate.version>4.3.11.Final</hibernate.version>
-		<mysql-connector-java.version>5.1.38</mysql-connector-java.version>
-
-		<!-- marshalling -->
-		<jackson.version>2.7.2</jackson.version>
-
+	    <fop.version>1.1</fop.version> 
+	    <avalon-framework.version>4.3</avalon-framework.version>
+	    <dbdoclet.version>8.0.2</dbdoclet.version>
+	    <jtidy.version>r938</jtidy.version>
 		<!-- logging -->
-		<org.slf4j.version>1.7.9</org.slf4j.version>
-		<logback.version>1.1.2</logback.version>
-
-		<!-- various -->
-		<hibernate-validator.version>5.1.3.Final</hibernate-validator.version>
-
-		<!-- util -->
-		<guava.version>19.0</guava.version>
-		<commons-lang3.version>3.3.2</commons-lang3.version>
+		<org.slf4j.version>1.7.21</org.slf4j.version>
+		<logback.version>1.1.7</logback.version>
 
 		<!-- testing -->
 		<org.hamcrest.version>1.3</org.hamcrest.version>
 		<junit.version>4.12</junit.version>
 		<mockito.version>1.10.19</mockito.version>
 
-		<httpcore.version>4.4</httpcore.version>
-		<httpclient.version>4.4</httpclient.version>
-
-		<rest-assured.version>2.9.0</rest-assured.version>
-
 		<!-- maven plugins -->
-		<maven-compiler-plugin.version>3.5.1</maven-compiler-plugin.version>
-		<maven-war-plugin.version>2.6</maven-war-plugin.version>
+		<maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
 		<maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
-		<maven-resources-plugin.version>2.7</maven-resources-plugin.version>
-		<cargo-maven2-plugin.version>1.4.18</cargo-maven2-plugin.version>
 
 	</properties>
 

apache-poi/.gitignore

@@ -0,0 +1 @@
+*.docx

apache-poi/pom.xml

@@ -0,0 +1,41 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>apache-poi</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <properties>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <junit.version>4.12</junit.version>
+        <poi.version>3.15</poi.version>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi-ooxml</artifactId>
+            <version>${poi.version}</version>
+        </dependency>
+    </dependencies>
+</project>

apache-poi/src/main/java/com/baeldung/poi/word/WordDocument.java

@@ -0,0 +1,91 @@
+package com.baeldung.poi.word;
+
+import org.apache.poi.util.Units;
+import org.apache.poi.xwpf.usermodel.*;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class WordDocument {
+    public static String logo = "logo-leaf.png";
+    public static String paragraph1 = "poi-word-para1.txt";
+    public static String paragraph2 = "poi-word-para2.txt";
+    public static String paragraph3 = "poi-word-para3.txt";
+    public static String output = "rest-with-spring.docx";
+
+    public void handleSimpleDoc() throws Exception {
+        XWPFDocument document = new XWPFDocument();
+
+        XWPFParagraph title = document.createParagraph();
+        title.setAlignment(ParagraphAlignment.CENTER);
+        XWPFRun titleRun = title.createRun();
+        titleRun.setText("Build Your REST API with Spring");
+        titleRun.setColor("009933");
+        titleRun.setBold(true);
+        titleRun.setFontFamily("Courier");
+        titleRun.setFontSize(20);
+
+        XWPFParagraph subTitle = document.createParagraph();
+        subTitle.setAlignment(ParagraphAlignment.CENTER);
+        XWPFRun subTitleRun = subTitle.createRun();
+        subTitleRun.setText("from HTTP fundamentals to API Mastery");
+        subTitleRun.setColor("00CC44");
+        subTitleRun.setFontFamily("Courier");
+        subTitleRun.setFontSize(16);
+        subTitleRun.setTextPosition(20);
+        subTitleRun.setUnderline(UnderlinePatterns.DOT_DOT_DASH);
+
+        XWPFParagraph image = document.createParagraph();
+        image.setAlignment(ParagraphAlignment.CENTER);
+        XWPFRun imageRun = image.createRun();
+        imageRun.setTextPosition(20);
+        Path imagePath = Paths.get(ClassLoader.getSystemResource(logo).toURI());
+        imageRun.addPicture(Files.newInputStream(imagePath), XWPFDocument.PICTURE_TYPE_PNG, imagePath.getFileName().toString(), Units.toEMU(50), Units.toEMU(50));
+
+        XWPFParagraph sectionTitle = document.createParagraph();
+        XWPFRun sectionTRun = sectionTitle.createRun();
+        sectionTRun.setText("What makes a good API?");
+        sectionTRun.setColor("00CC44");
+        sectionTRun.setBold(true);
+        sectionTRun.setFontFamily("Courier");
+
+        XWPFParagraph para1 = document.createParagraph();
+        para1.setAlignment(ParagraphAlignment.BOTH);
+        String string1 = convertTextFileToString(paragraph1);
+        XWPFRun para1Run = para1.createRun();
+        para1Run.setText(string1);
+
+        XWPFParagraph para2 = document.createParagraph();
+        para2.setAlignment(ParagraphAlignment.RIGHT);
+        String string2 = convertTextFileToString(paragraph2);
+        XWPFRun para2Run = para2.createRun();
+        para2Run.setText(string2);
+        para2Run.setItalic(true);
+
+        XWPFParagraph para3 = document.createParagraph();
+        para3.setAlignment(ParagraphAlignment.LEFT);
+        String string3 = convertTextFileToString(paragraph3);
+        XWPFRun para3Run = para3.createRun();
+        para3Run.setText(string3);
+
+        FileOutputStream out = new FileOutputStream(output);
+        document.write(out);
+        out.close();
+        document.close();
+    }
+
+    public String convertTextFileToString(String fileName) {
+        try (Stream<String> stream = Files.lines(Paths.get(ClassLoader.getSystemResource(fileName).toURI()))) {
+            return stream.collect(Collectors.joining(" "));
+        } catch (IOException | URISyntaxException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+}

apache-poi/src/main/resources/poi-word-para1.txt

@@ -0,0 +1 @@
+I published the first REST with Spring tutorials over four years ago, and after 300,000 readers and over a thousand personal questions over email, I am finally realizing that there is a huge education gap in the ecosystem.

apache-poi/src/main/resources/poi-word-para2.txt

@@ -0,0 +1,2 @@
+I had to learn what makes a good API is the hard way, and I couldn’t find anything out there to help me speed things up.
+It took me 3 years, more than 10 production grade APIs built from scratch and a decent number of mistakes to get to a mature understanding of how an API should really be done well.

apache-poi/src/main/resources/poi-word-para3.txt

@@ -0,0 +1,3 @@
+Sure, there were tutorials and random code samples out there, but nothing coherent.
+Nothing start to finish to act as a guide through the challenges of building a mature API with Spring.
+The educational gap between beginner and the API professional remains vast.

apache-poi/src/test/java/com/baeldung/poi/word/WordTest.java

@@ -0,0 +1,47 @@
+package com.baeldung.poi.word;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+
+import org.apache.poi.xwpf.usermodel.XWPFDocument;
+import org.apache.poi.xwpf.usermodel.XWPFParagraph;
+import org.apache.poi.xwpf.usermodel.XWPFRun;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class WordTest {
+    static WordDocument wordDocument;
+
+    @BeforeClass
+    public static void generateMSWordFile() throws Exception {
+        WordTest.wordDocument = new WordDocument();
+        wordDocument.handleSimpleDoc();
+    }
+
+    @Test
+    public void whenParsingOutputDocument_thenCorrect() throws Exception {
+        Path msWordPath = Paths.get(WordDocument.output);
+        XWPFDocument document = new XWPFDocument(Files.newInputStream(msWordPath));
+        List<XWPFParagraph> paragraphs = document.getParagraphs();
+        document.close();
+
+        XWPFParagraph title = paragraphs.get(0);
+        XWPFRun titleRun = title.getRuns().get(0);
+        assertEquals("Build Your REST API with Spring", title.getText());
+        assertEquals("009933", titleRun.getColor());
+        assertTrue(titleRun.isBold());
+        assertEquals("Courier", titleRun.getFontFamily());
+        assertEquals(20, titleRun.getFontSize());
+
+        assertEquals("from HTTP fundamentals to API Mastery", paragraphs.get(1).getText());
+        assertEquals("What makes a good API?", paragraphs.get(3).getText());
+        assertEquals(wordDocument.convertTextFileToString(WordDocument.paragraph1), paragraphs.get(4).getText());
+        assertEquals(wordDocument.convertTextFileToString(WordDocument.paragraph2), paragraphs.get(5).getText());
+        assertEquals(wordDocument.convertTextFileToString(WordDocument.paragraph3), paragraphs.get(6).getText());
+    }
+}

aspectj/pom.xml

@@ -98,13 +98,14 @@
                     <execution>
                         <goals>
                             <goal>compile</goal>
-                               <goal>test-compile</goal> 
+                            <goal>test-compile</goal> 
                         </goals>
                     </execution>
                 </executions>
            </plugin>
             
-            <!-- <plugin>
+            <!-- 
+            <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>2.10</version>
@@ -113,18 +114,18 @@
                     <useSystemClassLoader>true</useSystemClassLoader>
                     <forkMode>always</forkMode>
                 </configuration>
-            </plugin>   -->
+            </plugin>
+             -->
         </plugins>
     </build>
 
     <properties>
         <source.version>1.8</source.version>
-        <aspectj.version>1.6.11</aspectj.version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <aspectj.version>1.8.9</aspectj.version>
         <org.slf4j.version>1.7.21</org.slf4j.version>
         <logback.version>1.1.7</logback.version>
-        <maven-compiler-plugin.version>3.5.1</maven-compiler-plugin.version>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
         <junit.version>4.12</junit.version>
     </properties>
 

aspectj/src/main/java/com/baeldung/aspectj/Account.java

@@ -4,10 +4,10 @@ public class Account {
     int balance = 20;
 
     public boolean withdraw(int amount) {
-        if (balance - amount > 0) {
-            balance = balance - amount;
-            return true;
-        } else
+        if (balance < amount) {
             return false;
+        }
+        balance = balance - amount;
+        return true;
     }
 }

aspectj/src/main/java/com/baeldung/aspectj/AccountAspect.aj

@@ -16,12 +16,11 @@ public aspect AccountAspect {
     }
 
     boolean around(int amount, Account account) : callWithDraw(amount, account) {
-        if (account.balance - amount >= MIN_BALANCE)
-            return proceed(amount, account);
-        else {
+        if (account.balance < amount) {
             logger.info("Withdrawal Rejected!");
             return false;
         }
+        return proceed(amount, account);
     }
 
     after(int amount, Account balance) : callWithDraw(amount, balance) {

assertj/pom.xml

@@ -23,13 +23,13 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
-            <version>3.5.1</version>
+            <version>${assertj-core.version}</version>
             <scope>test</scope>
         </dependency>
 
@@ -40,7 +40,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.3</version>
+                <version>${maven-compiler-plugin.version}</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>
@@ -51,6 +51,11 @@
 
     <properties>
         <guava.version>19.0</guava.version>
+        <assertj-guava.version>3.1.0</assertj-guava.version>
+        <junit.version>4.12</junit.version>
+        <assertj-core.version>3.6.1</assertj-core.version>
+        
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
     </properties>
     
 </project>

autovalue/pom.xml

@@ -2,15 +2,16 @@
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
-    <artifactId>autovalue-tutorial</artifactId>
+    <artifactId>autovalue</artifactId>
     <version>1.0</version>
-    <name>AutoValue</name>
+    <name>autovalue</name>
+
     <build>
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.3</version>
+                <version>${maven-compiler-plugin.version}</version>
                 <configuration>
                     <source>7</source>
                     <target>7</target>
@@ -19,19 +20,26 @@
             </plugin>
         </plugins>
     </build>
+
     <dependencies>
         <dependency>
             <groupId>com.google.auto.value</groupId>
             <artifactId>auto-value</artifactId>
-            <version>1.2</version>
+            <version>${auto-value.version}</version>
         </dependency>
 
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.3</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
-
     </dependencies>
+
+    <properties>
+        <auto-value.version>1.3</auto-value.version>
+        <junit.version>4.12</junit.version>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+    </properties>
+    
 </project>

autovalue/src/test/java/com/baeldung/autovalue/MoneyUnitTest.java

@@ -4,7 +4,7 @@ import static org.junit.Assert.*;
 
 import org.junit.Test;
 
-public class MoneyTest {
+public class MoneyUnitTest {
 	@Test
 	public void givenTwoSameValueMoneyObjects_whenEqualityTestFails_thenCorrect() {
 		MutableMoney m1 = new MutableMoney(10000, "USD");

aws-lambda/pom.xml

@@ -0,0 +1,44 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>com.baeldung</groupId>
+	<artifactId>aws-lambda</artifactId>
+	<version>0.1.0-SNAPSHOT</version>
+	<packaging>jar</packaging>
+	<name>aws-lambda</name>
+
+	<dependencies>
+		<dependency>
+			<groupId>com.amazonaws</groupId>
+			<artifactId>aws-lambda-java-core</artifactId>
+			<version>1.1.0</version>
+		</dependency>
+
+		<dependency>
+			<groupId>commons-io</groupId>
+			<artifactId>commons-io</artifactId>
+			<version>2.5</version>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-shade-plugin</artifactId>
+				<version>2.3</version>
+				<configuration>
+					<createDependencyReducedPom>false</createDependencyReducedPom>
+				</configuration>
+				<executions>
+					<execution>
+						<phase>package</phase>
+						<goals>
+							<goal>shade</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
+		</plugins>
+	</build>
+</project>

aws-lambda/src/main/java/com/baeldung/LambdaMethodHandler.java

@@ -0,0 +1,10 @@
+package com.baeldung;
+
+import com.amazonaws.services.lambda.runtime.Context;
+
+public class LambdaMethodHandler {
+    public String handleRequest(String input, Context context) {
+        context.getLogger().log("Input: " + input);
+        return "Hello World - " + input;
+    }
+}

aws-lambda/src/main/java/com/baeldung/LambdaRequestHandler.java

@@ -0,0 +1,11 @@
+package com.baeldung;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+
+public class LambdaRequestHandler implements RequestHandler<String, String> {
+    public String handleRequest(String input, Context context) {
+        context.getLogger().log("Input: " + input);
+        return "Hello World - " + input;
+    }
+}

aws-lambda/src/main/java/com/baeldung/LambdaRequestStreamHandler.java

@@ -0,0 +1,18 @@
+package com.baeldung;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+import com.amazonaws.services.lambda.runtime.RequestStreamHandler;
+import org.apache.commons.io.IOUtils;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class LambdaRequestStreamHandler implements RequestStreamHandler {
+
+    public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
+        String input = IOUtils.toString(inputStream, "UTF-8");
+        outputStream.write(("Hello World - " + input).getBytes());
+    }
+}

cdi/pom.xml

@@ -22,18 +22,18 @@
         <dependency>
             <groupId>org.aspectj</groupId>
             <artifactId>aspectjweaver</artifactId>
-            <version>1.8.9</version>
+            <version>${aspectjweaver.version}</version>
         </dependency>
         <dependency>
             <groupId>org.jboss.weld.se</groupId>
             <artifactId>weld-se-core</artifactId>
-            <version>2.3.5.Final</version>
+            <version>${weld-se-core.version}</version>
         </dependency>
 
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -97,7 +97,10 @@
         </profile>
     </profiles>
     <properties>
-        <spring.version>4.3.1.RELEASE</spring.version>
+        <spring.version>4.3.4.RELEASE</spring.version>
+        <aspectjweaver.version>1.8.9</aspectjweaver.version>
+        <weld-se-core.version>2.4.1.Final</weld-se-core.version>
+        <junit.version>4.12</junit.version>
         <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>        
     </properties>
 

core-java-9/README.md

@@ -3,3 +3,6 @@
 ## Core Java 9  Examples
 
 [Java 9 New Features](http://www.baeldung.com/new-java-9)
+
+### Relevant Articles:
+- [Java 9 Stream API Improvements](http://www.baeldung.com/java-9-stream-api)

core-java-9/pom.xml

@@ -76,9 +76,7 @@
 
 	<properties>
 		<!-- logging -->
-		<org.slf4j.version>1.7.13</org.slf4j.version>
-		<logback.version>1.0.13</logback.version>
-
+		<org.slf4j.version>1.7.21</org.slf4j.version>
 
 		<!-- maven plugins -->
 		<maven-compiler-plugin.version>3.6-jigsaw-SNAPSHOT</maven-compiler-plugin.version>	

core-java/.gitignore

@@ -13,4 +13,6 @@
 *.ear
 
 # Files generated by integration tests
-*.txt
+*.txt
+/bin/
+/temp

core-java/README.md

@@ -38,3 +38,11 @@
 - [Guide to the Fork/Join Framework in Java](http://www.baeldung.com/java-fork-join)
 - [How to Print Screen in Java](http://www.baeldung.com/print-screen-in-java)
 - [How to Convert String to different data types in Java](http://www.baeldung.com/java-string-conversions)
+- [Introduction to Java Generics](http://www.baeldung.com/java-generics)
+- [Generate equals() and hashCode() with Eclipse](http://www.baeldung.com/java-eclipse-equals-and-hashcode)
+- [A Guide To Java Regular Expressions API](http://www.baeldung.com/regular-expressions-java)
+- [Sorting in Java](http://www.baeldung.com/java-sorting)
+- [Getting Started with Java Properties](http://www.baeldung.com/java-properties)
+- [Grep in Java](http://www.baeldung.com/grep-in-java)
+- [Java - Combine Multiple Collections](http://www.baeldung.com/java-combine-multiple-collections)
+- [Simulated Annealing for Travelling Salesman Problem](http://www.baeldung.com/java-simulated-annealing-for-traveling-salesman)

core-java/pom.xml

@@ -1,291 +1,314 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-	<modelVersion>4.0.0</modelVersion>
-	<groupId>com.baeldung</groupId>
-	<artifactId>core-java</artifactId>
-	<version>0.1.0-SNAPSHOT</version>
-	<packaging>jar</packaging>
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>core-java</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
 
-	<name>core-java</name>
+    <name>core-java</name>
 
-	<dependencies>
+    <dependencies>
 
-		<!-- utils -->
-		<dependency>
-			<groupId>net.sourceforge.collections</groupId>
-			<artifactId>collections-generic</artifactId>
-			<version>4.01</version>
-		</dependency>
-		<dependency>
-			<groupId>com.google.guava</groupId>
-			<artifactId>guava</artifactId>
-			<version>${guava.version}</version>
-		</dependency>
+        <!-- utils -->
+        <dependency>
+            <groupId>net.sourceforge.collections</groupId>
+            <artifactId>collections-generic</artifactId>
+            <version>${collections-generic.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
 
-		<dependency>
-			<groupId>org.apache.commons</groupId>
-			<artifactId>commons-collections4</artifactId>
-			<version>4.0</version>
-		</dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
 
-		<dependency>
-			<groupId>commons-io</groupId>
-			<artifactId>commons-io</artifactId>
-			<version>2.4</version>
-		</dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
 
-		<dependency>
-			<groupId>org.apache.commons</groupId>
-			<artifactId>commons-lang3</artifactId>
-			<version>${commons-lang3.version}</version>
-		</dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
 
-		<dependency>
-			<groupId>org.apache.commons</groupId>
-			<artifactId>commons-math3</artifactId>
-			<version>3.3</version>
-		</dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${commons-math3.version}</version>
+        </dependency>
 
-		<dependency>
-			<groupId>org.bouncycastle</groupId>
-			<artifactId>bcprov-jdk15on</artifactId>
-			<version>${bouncycastle.version}</version>
-		</dependency>
-		<!-- web -->
+        <dependency>
+            <groupId>org.bouncycastle</groupId>
+            <artifactId>bcprov-jdk15on</artifactId>
+            <version>${bouncycastle.version}</version>
+        </dependency>
 
-		<!-- marshalling -->
+        <dependency>
+            <groupId>org.unix4j</groupId>
+            <artifactId>unix4j-command</artifactId>
+            <version>${unix4j.version}</version>
+        </dependency>
 
-		<dependency>
-			<groupId>com.fasterxml.jackson.core</groupId>
-			<artifactId>jackson-databind</artifactId>
-			<version>${jackson.version}</version>
-		</dependency>
+        <dependency>
+            <groupId>com.googlecode.grep4j</groupId>
+            <artifactId>grep4j</artifactId>
+            <version>${grep4j.version}</version>
+        </dependency>
+        <!-- web -->
 
-		<!-- logging -->
+        <!-- marshalling -->
 
-		<dependency>
-			<groupId>org.slf4j</groupId>
-			<artifactId>slf4j-api</artifactId>
-			<version>${org.slf4j.version}</version>
-		</dependency>
-		<dependency>
-			<groupId>ch.qos.logback</groupId>
-			<artifactId>logback-classic</artifactId>
-			<version>${logback.version}</version>
-			<!-- <scope>runtime</scope> -->
-		</dependency>
-		<dependency>
-			<groupId>org.slf4j</groupId>
-			<artifactId>jcl-over-slf4j</artifactId>
-			<version>${org.slf4j.version}</version>
-			<!-- <scope>runtime</scope> --> <!-- some spring dependencies need to compile against jcl -->
-		</dependency>
-		<dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
-			<groupId>org.slf4j</groupId>
-			<artifactId>log4j-over-slf4j</artifactId>
-			<version>${org.slf4j.version}</version>
-		</dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
 
-		<!-- test scoped -->
+        <!-- logging -->
 
-		<dependency>
-			<groupId>junit</groupId>
-			<artifactId>junit</artifactId>
-			<version>${junit.version}</version>
-			<scope>test</scope>
-		</dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>${logback.version}</version>
+            <!-- <scope>runtime</scope> -->
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>jcl-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+            <!-- <scope>runtime</scope> --> <!-- some spring dependencies need to compile against jcl -->
+        </dependency>
+        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
+            <groupId>org.slf4j</groupId>
+            <artifactId>log4j-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
 
-		<dependency>
-			<groupId>org.hamcrest</groupId>
-			<artifactId>hamcrest-core</artifactId>
-			<version>${org.hamcrest.version}</version>
-			<scope>test</scope>
-		</dependency>
-		<dependency>
-			<groupId>org.hamcrest</groupId>
-			<artifactId>hamcrest-library</artifactId>
-			<version>${org.hamcrest.version}</version>
-			<scope>test</scope>
-		</dependency>
+        <!-- test scoped -->
 
-		<dependency>
-			<groupId>org.assertj</groupId>
-			<artifactId>assertj-core</artifactId>
-			<version>${assertj.version}</version>
-			<scope>test</scope>
-		</dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-all</artifactId>
+            <version>1.3</version>
+            <scope>test</scope>
+        </dependency>
 
-		<dependency>
-			<groupId>org.testng</groupId>
-			<artifactId>testng</artifactId>
-			<version>${testng.version}</version>
-			<scope>test</scope>
-		</dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
 
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-core</artifactId>
+            <version>${org.hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-library</artifactId>
+            <version>${org.hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
 
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
 
-		<dependency>
-			<groupId>org.mockito</groupId>
-			<artifactId>mockito-core</artifactId>
-			<version>${mockito.version}</version>
-			<scope>test</scope>
-		</dependency>
+        <dependency>
+            <groupId>org.testng</groupId>
+            <artifactId>testng</artifactId>
+            <version>${testng.version}</version>
+            <scope>test</scope>
+        </dependency>
 
-		<dependency>
-			<groupId>commons-codec</groupId>
-			<artifactId>commons-codec</artifactId>
-			<version>${commons-codec.version}</version>
-		</dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${mockito.version}</version>
+            <scope>test</scope>
+        </dependency>
 
-	</dependencies>
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
 
-	<build>
-		<finalName>core-java</finalName>
-		<resources>
-			<resource>
-				<directory>src/main/resources</directory>
-				<filtering>true</filtering>
-			</resource>
-		</resources>
+    </dependencies>
 
-		<plugins>
+    <build>
+        <finalName>core-java</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
 
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-compiler-plugin</artifactId>
-				<version>${maven-compiler-plugin.version}</version>
-				<configuration>
-					<source>1.8</source>
-					<target>1.8</target>
-				</configuration>
-			</plugin>
+        <plugins>
 
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-surefire-plugin</artifactId>
-				<version>${maven-surefire-plugin.version}</version>
-				<configuration>
-					<excludes>
-						<exclude>**/*IntegrationTest.java</exclude>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${maven-surefire-plugin.version}</version>
+                <configuration>
+                    <excludes>
+                        <exclude>**/*IntegrationTest.java</exclude>
                         <exclude>**/*LongRunningUnitTest.java</exclude>
                         <exclude>**/*ManualTest.java</exclude>
-					</excludes>
-				</configuration>
-			</plugin>
+                    </excludes>
+                    <testFailureIgnore>true</testFailureIgnore>
+                </configuration>
+            </plugin>
 
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-dependency-plugin</artifactId>
-				<executions>
-					<execution>
-						<id>copy-dependencies</id>
-						<phase>prepare-package</phase>
-						<goals>
-							<goal>copy-dependencies</goal>
-						</goals>
-						<configuration>
-							<outputDirectory>${project.build.directory}/libs</outputDirectory>
-						</configuration>
-					</execution>
-				</executions>
-			</plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>copy-dependencies</id>
+                        <phase>prepare-package</phase>
+                        <goals>
+                            <goal>copy-dependencies</goal>
+                        </goals>
+                        <configuration>
+                            <outputDirectory>${project.build.directory}/libs</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
 
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-jar-plugin</artifactId>
-				<configuration>
-					<archive>
-						<manifest>
-							<addClasspath>true</addClasspath>
-							<classpathPrefix>libs/</classpathPrefix>
-							<mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-						</manifest>
-					</archive>
-				</configuration>
-			</plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-jar-plugin</artifactId>
+                <configuration>
+                    <archive>
+                        <manifest>
+                            <addClasspath>true</addClasspath>
+                            <classpathPrefix>libs/</classpathPrefix>
+                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+            </plugin>
 
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-assembly-plugin</artifactId>
-				<executions>
-					<execution>
-						<phase>package</phase>
-						<goals>
-							<goal>single</goal>
-						</goals>
-						<configuration>
-							<archive>
-								<manifest>
-									<mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-								</manifest>
-							</archive>
-							<descriptorRefs>
-								<descriptorRef>jar-with-dependencies</descriptorRef>
-							</descriptorRefs>
-						</configuration>
-					</execution>
-				</executions>
-			</plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>single</goal>
+                        </goals>
+                        <configuration>
+                            <archive>
+                                <manifest>
+                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                </manifest>
+                            </archive>
+                            <descriptorRefs>
+                                <descriptorRef>jar-with-dependencies</descriptorRef>
+                            </descriptorRefs>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
 
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-shade-plugin</artifactId>
-				<executions>
-					<execution>
-						<goals>
-							<goal>shade</goal>
-						</goals>
-						<configuration>
-							<shadedArtifactAttached>true</shadedArtifactAttached>
-							<transformers>
-								<transformer
-									implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-									<mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-								</transformer>
-							</transformers>
-						</configuration>
-					</execution>
-				</executions>
-			</plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                        <configuration>
+                            <shadedArtifactAttached>true</shadedArtifactAttached>
+                            <transformers>
+                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                </transformer>
+                            </transformers>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
 
-			<plugin>
-				<groupId>com.jolira</groupId>
-				<artifactId>onejar-maven-plugin</artifactId>
-				<executions>
-					<execution>
-						<configuration>
-							<mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-							<attachToBuild>true</attachToBuild>
-							<filename>${project.build.finalName}-onejar.${project.packaging}</filename>
-						</configuration>
-						<goals>
-							<goal>one-jar</goal>
-						</goals>
-					</execution>
-				</executions>
-			</plugin>
+            <plugin>
+                <groupId>com.jolira</groupId>
+                <artifactId>onejar-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <configuration>
+                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <attachToBuild>true</attachToBuild>
+                            <filename>${project.build.finalName}-onejar.${project.packaging}</filename>
+                        </configuration>
+                        <goals>
+                            <goal>one-jar</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
 
-			<plugin>
-				<groupId>org.springframework.boot</groupId>
-				<artifactId>spring-boot-maven-plugin</artifactId>
-				<executions>
-					<execution>
-						<goals>
-							<goal>repackage</goal>
-						</goals>
-						<configuration>
-							<classifier>spring-boot</classifier>
-							<mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
-						</configuration>
-					</execution>
-				</executions>
-			</plugin>
-			
-		</plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>repackage</goal>
+                        </goals>
+                        <configuration>
+                            <classifier>spring-boot</classifier>
+                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
 
-	</build>
-	
-	<profiles>
+        </plugins>
+
+    </build>
+
+    <profiles>
         <profile>
             <id>integration</id>
             <build>
@@ -320,46 +343,38 @@
         </profile>
     </profiles>
 
-	<properties>
-		<!-- persistence -->
-		<hibernate.version>4.3.11.Final</hibernate.version>
-		<mysql-connector-java.version>5.1.38</mysql-connector-java.version>
+    <properties>
+        <!-- marshalling -->
+        <jackson.version>2.8.5</jackson.version>
 
-		<!-- marshalling -->
-		<jackson.version>2.7.8</jackson.version>
+        <!-- logging -->
+        <org.slf4j.version>1.7.21</org.slf4j.version>
+        <logback.version>1.1.7</logback.version>
 
-		<!-- logging -->
-		<org.slf4j.version>1.7.13</org.slf4j.version>
-		<logback.version>1.1.3</logback.version>
+        <!-- util -->
+        <guava.version>19.0</guava.version>
+        <commons-lang3.version>3.5</commons-lang3.version>
+        <bouncycastle.version>1.55</bouncycastle.version>
+        <commons-codec.version>1.10</commons-codec.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+        <commons-io.version>2.5</commons-io.version>
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <collections-generic.version>4.01</collections-generic.version>
+        <unix4j.version>0.4</unix4j.version>
+        <grep4j.version>1.8.7</grep4j.version>
+        <lombok.version>1.16.12</lombok.version>
 
-		<!-- various -->
-		<hibernate-validator.version>5.1.3.Final</hibernate-validator.version>
+        <!-- testing -->
+        <org.hamcrest.version>1.3</org.hamcrest.version>
+        <junit.version>4.12</junit.version>
+        <mockito.version>1.10.19</mockito.version>
+        <testng.version>6.10</testng.version>
+        <assertj.version>3.6.1</assertj.version>
 
-		<!-- util -->
-		<guava.version>19.0</guava.version>
-		<commons-lang3.version>3.4</commons-lang3.version>
-		<bouncycastle.version>1.55</bouncycastle.version>
-		<commons-codec.version>1.10</commons-codec.version>
+        <!-- maven plugins -->
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
 
-		<!-- testing -->
-		<org.hamcrest.version>1.3</org.hamcrest.version>
-		<junit.version>4.12</junit.version>
-		<mockito.version>1.10.19</mockito.version>
-		<testng.version>6.8</testng.version>
-		<assertj.version>3.5.1</assertj.version>
-
-		<httpcore.version>4.4.1</httpcore.version>
-		<httpclient.version>4.5</httpclient.version>
-
-		<rest-assured.version>2.9.0</rest-assured.version>
-
-		<!-- maven plugins -->
-		<maven-compiler-plugin.version>3.5.1</maven-compiler-plugin.version>
-		<maven-war-plugin.version>2.6</maven-war-plugin.version>
-		<maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
-		<maven-resources-plugin.version>2.7</maven-resources-plugin.version>
-		<cargo-maven2-plugin.version>1.4.18</cargo-maven2-plugin.version>
-
-	</properties>
+    </properties>
 
 </project>

core-java/src/main/java/com/baeldung/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [SHA-256 Hashing in Java](http://www.baeldung.com/sha-256-hashing-java)

core-java/src/main/java/com/baeldung/algorithms/RunAlgorithm.java

@@ -0,0 +1,31 @@
+package com.baeldung.algorithms;
+
+import java.util.Scanner;
+
+import com.baeldung.algorithms.annealing.SimulatedAnnealing;
+import com.baeldung.algorithms.slope_one.SlopeOne;
+
+public class RunAlgorithm {
+
+	public static void main(String[] args) {
+		Scanner in = new Scanner(System.in);
+		System.out.println("Run algorithm:");
+		System.out.println("1 - Simulated Annealing");
+		System.out.println("2 - Slope One");
+		int decision = in.nextInt();
+		switch (decision) {
+		case 1:
+			System.out.println(
+					"Optimized distance for travel: " + SimulatedAnnealing.simulateAnnealing(10, 10000, 0.9995));
+			break;
+		case 2:
+			SlopeOne.slopeOne(3);
+			break;
+		default:
+			System.out.println("Unknown option");
+			break;
+		}
+		in.close();
+	}
+
+}

core-java/src/main/java/com/baeldung/algorithms/annealing/City.java

@@ -0,0 +1,22 @@
+package com.baeldung.algorithms.annealing;
+
+import lombok.Data;
+
+@Data
+public class City {
+
+	private int x;
+	private int y;
+
+	public City() {
+		this.x = (int) (Math.random() * 500);
+		this.y = (int) (Math.random() * 500);
+	}
+
+	public double distanceToCity(City city) {
+		int x = Math.abs(getX() - city.getX());
+		int y = Math.abs(getY() - city.getY());
+		return Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
+	}
+
+}

core-java/src/main/java/com/baeldung/algorithms/annealing/SimulatedAnnealing.java

@@ -0,0 +1,36 @@
+package com.baeldung.algorithms.annealing;
+
+public class SimulatedAnnealing {
+
+    private static Travel travel = new Travel(10);
+
+    public static double simulateAnnealing(double startingTemperature, int numberOfIterations, double coolingRate) {
+        System.out.println("Starting SA with temperature: " + startingTemperature + ", # of iterations: " + numberOfIterations + " and colling rate: " + coolingRate);
+        double t = startingTemperature;
+        travel.generateInitialTravel();
+        double bestDistance = travel.getDistance();
+        System.out.println("Initial distance of travel: " + bestDistance);
+        Travel bestSolution = travel;
+        Travel currentSolution = bestSolution;
+
+        for (int i = 0; i < numberOfIterations; i++) {
+            if (t > 0.1) {
+                currentSolution.swapCities();
+                double currentDistance = currentSolution.getDistance();
+                if (currentDistance < bestDistance) {
+                    bestDistance = currentDistance;
+                } else if (Math.exp((bestDistance - currentDistance) / t) < Math.random()) {
+                    currentSolution.revertSwap();
+                }
+                t *= coolingRate;
+            } else {
+            	continue;
+            }
+            if (i % 100 == 0) {
+                System.out.println("Iteration #" + i);
+            }
+        }
+        return bestDistance;
+    }
+
+}

core-java/src/main/java/com/baeldung/algorithms/annealing/Travel.java

@@ -0,0 +1,63 @@
+package com.baeldung.algorithms.annealing;
+
+import java.util.ArrayList;
+import java.util.Collections;
+
+import lombok.Data;
+
+@Data
+public class Travel {
+
+    private ArrayList<City> travel = new ArrayList<>();
+    private ArrayList<City> previousTravel = new ArrayList<>();
+
+    public Travel(int numberOfCities) {
+        for (int i = 0; i < numberOfCities; i++) {
+            travel.add(new City());
+        }
+    }
+
+    public void generateInitialTravel() {
+        if (travel.isEmpty())
+            new Travel(10);
+        Collections.shuffle(travel);
+    }
+
+    public void swapCities() {
+        int a = generateRandomIndex();
+        int b = generateRandomIndex();
+        previousTravel = travel;
+        City x = travel.get(a);
+        City y = travel.get(b);
+        travel.set(a, y);
+        travel.set(b, x);
+    }
+
+    public void revertSwap() {
+        travel = previousTravel;
+    }
+
+    private int generateRandomIndex() {
+        return (int) (Math.random() * travel.size());
+    }
+
+    public City getCity(int index) {
+        return travel.get(index);
+    }
+
+    public int getDistance() {
+        int distance = 0;
+        for (int index = 0; index < travel.size(); index++) {
+            City starting = getCity(index);
+            City destination;
+            if (index + 1 < travel.size()) {
+                destination = getCity(index + 1);
+            } else {
+                destination = getCity(0);
+            }
+            distance += starting.distanceToCity(destination);
+        }
+        return distance;
+    }
+
+}

core-java/src/main/java/com/baeldung/algorithms/slope_one/InputData.java

@@ -0,0 +1,36 @@
+package com.baeldung.algorithms.slope_one;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import lombok.Data;
+
+@Data
+public class InputData {
+	
+	protected static List<Item> items = Arrays.asList(new Item("Candy"), new Item("Drink"), new Item("Soda"), new Item("Popcorn"),
+			new Item("Snacks"));
+
+	public static Map<User, HashMap<Item, Double>> initializeData(int numberOfUsers) {
+		Map<User, HashMap<Item, Double>> data = new HashMap<>();
+		HashMap<Item, Double> newUser;
+		Set<Item> newRecommendationSet;
+		for (int i = 0; i < numberOfUsers; i++) {
+			newUser = new HashMap<Item, Double>();
+			newRecommendationSet = new HashSet<>();
+			for (int j = 0; j < 3; j++) {
+				newRecommendationSet.add(items.get((int) (Math.random() * 5)));
+			}
+			for (Item item : newRecommendationSet) {
+				newUser.put(item, Math.random());
+			}
+			data.put(new User("User " + i), newUser);
+		}
+		return data;
+	}
+
+}

core-java/src/main/java/com/baeldung/algorithms/slope_one/Item.java

@@ -0,0 +1,13 @@
+package com.baeldung.algorithms.slope_one;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+public class Item {
+
+	private String itemName;
+}

core-java/src/main/java/com/baeldung/algorithms/slope_one/SlopeOne.java

@@ -0,0 +1,124 @@
+package com.baeldung.algorithms.slope_one;
+
+import java.text.DecimalFormat;
+import java.text.NumberFormat;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+
+/**
+ * Slope One algorithm implementation
+ */
+public class SlopeOne {
+
+	private static Map<Item, Map<Item, Double>> diff = new HashMap<>();
+	private static Map<Item, Map<Item, Integer>> freq = new HashMap<>();
+	private static Map<User, HashMap<Item, Double>> inputData;
+	private static Map<User, HashMap<Item, Double>> outputData = new HashMap<>();
+
+	public static void slopeOne(int numberOfUsers) {
+		inputData = InputData.initializeData(numberOfUsers);
+		System.out.println("Slope One - Before the Prediction\n");
+		buildDifferencesMatrix(inputData);
+		System.out.println("\nSlope One - With Predictions\n");
+		predict(inputData);
+	}
+
+	/**
+	 * Based on the available data, calculate the relationships between the
+	 * items and number of occurences
+	 * 
+	 * @param data
+	 *            existing user data and their items' ratings
+	 */
+	private static void buildDifferencesMatrix(Map<User, HashMap<Item, Double>> data) {
+		for (HashMap<Item, Double> user : data.values()) {
+			for (Entry<Item, Double> e : user.entrySet()) {
+				if (!diff.containsKey(e.getKey())) {
+					diff.put(e.getKey(), new HashMap<Item, Double>());
+					freq.put(e.getKey(), new HashMap<Item, Integer>());
+				}
+				for (Entry<Item, Double> e2 : user.entrySet()) {
+					int oldCount = 0;
+					if (freq.get(e.getKey()).containsKey(e2.getKey())) {
+						oldCount = freq.get(e.getKey()).get(e2.getKey()).intValue();
+					}
+					double oldDiff = 0.0;
+					if (diff.get(e.getKey()).containsKey(e2.getKey())) {
+						oldDiff = diff.get(e.getKey()).get(e2.getKey()).doubleValue();
+					}
+					double observedDiff = e.getValue() - e2.getValue();
+					freq.get(e.getKey()).put(e2.getKey(), oldCount + 1);
+					diff.get(e.getKey()).put(e2.getKey(), oldDiff + observedDiff);
+				}
+			}
+		}
+		for (Item j : diff.keySet()) {
+			for (Item i : diff.get(j).keySet()) {
+				double oldValue = diff.get(j).get(i).doubleValue();
+				int count = freq.get(j).get(i).intValue();
+				diff.get(j).put(i, oldValue / count);
+			}
+		}
+		printData(data);
+	}
+
+	/**
+	 * Based on existing data predict all missing ratings. If prediction is not
+	 * possible, the value will be equal to -1
+	 * 
+	 * @param data
+	 *            existing user data and their items' ratings
+	 */
+	private static void predict(Map<User, HashMap<Item, Double>> data) {
+		HashMap<Item, Double> uPred = new HashMap<Item, Double>();
+		HashMap<Item, Integer> uFreq = new HashMap<Item, Integer>();
+		for (Item j : diff.keySet()) {
+			uFreq.put(j, 0);
+			uPred.put(j, 0.0);
+		}
+		for (Entry<User, HashMap<Item, Double>> e : data.entrySet()) {
+			for (Item j : e.getValue().keySet()) {
+				for (Item k : diff.keySet()) {
+					try {
+						double predictedValue = diff.get(k).get(j).doubleValue() + e.getValue().get(j).doubleValue();
+						double finalValue = predictedValue * freq.get(k).get(j).intValue();
+						uPred.put(k, uPred.get(k) + finalValue);
+						uFreq.put(k, uFreq.get(k) + freq.get(k).get(j).intValue());
+					} catch (NullPointerException e1) {
+					}
+				}
+			}
+			HashMap<Item, Double> clean = new HashMap<Item, Double>();
+			for (Item j : uPred.keySet()) {
+				if (uFreq.get(j) > 0) {
+					clean.put(j, uPred.get(j).doubleValue() / uFreq.get(j).intValue());
+				}
+			}
+			for (Item j : InputData.items) {
+				if (e.getValue().containsKey(j)) {
+					clean.put(j, e.getValue().get(j));
+				} else {
+					clean.put(j, -1.0);
+				}
+			}
+			outputData.put(e.getKey(), clean);
+		}
+		printData(outputData);
+	}
+
+	private static void printData(Map<User, HashMap<Item, Double>> data) {
+		for (User user : data.keySet()) {
+			System.out.println(user.getUsername() + ":");
+			print(data.get(user));
+		}
+	}
+
+	private static void print(HashMap<Item, Double> hashMap) {
+		NumberFormat formatter = new DecimalFormat("#0.000");
+		for (Item j : hashMap.keySet()) {
+			System.out.println(" " + j.getItemName() + " --> " + formatter.format(hashMap.get(j).doubleValue()));
+		}
+	}
+
+}

core-java/src/main/java/com/baeldung/algorithms/slope_one/User.java

@@ -0,0 +1,14 @@
+package com.baeldung.algorithms.slope_one;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+public class User {
+	
+	private String username;
+
+}

core-java/src/main/java/com/baeldung/dirmonitoring/DirectoryMonitoringExample.java

@@ -0,0 +1,38 @@
+package com.baeldung.dirmonitoring;
+
+import java.io.File;
+
+import org.apache.commons.io.monitor.FileAlterationListener;
+import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
+import org.apache.commons.io.monitor.FileAlterationMonitor;
+import org.apache.commons.io.monitor.FileAlterationObserver;
+
+public class DirectoryMonitoringExample {
+
+    public static final int POLL_INTERVAL = 500;
+
+    public static void main(String[] args) throws Exception {
+        FileAlterationObserver observer = new FileAlterationObserver(System.getProperty("user.home"));
+        FileAlterationMonitor monitor = new FileAlterationMonitor(POLL_INTERVAL);
+        FileAlterationListener listener = new FileAlterationListenerAdaptor() {
+            @Override
+            public void onFileCreate(File file) {
+                System.out.println("File: " + file.getName() + " created");
+            }
+
+            @Override
+            public void onFileDelete(File file) {
+                System.out.println("File: " + file.getName() + " deleted");
+            }
+
+            @Override
+            public void onFileChange(File file) {
+                System.out.println("File: " + file.getName() + " changed");
+            }
+        };
+        observer.addListener(listener);
+        monitor.addObserver(observer);
+        monitor.start();
+
+    }
+}

core-java/src/main/java/com/baeldung/generics/Building.java

@@ -1,5 +1,12 @@
+package com.baeldung.generics;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class Building {
-	public void paint() {
-	}
+    private static final Logger LOGGER = LoggerFactory.getLogger(Building.class);
+
+    public void paint() {
+        LOGGER.info("Painting Building");
+    }
 }

core-java/src/main/java/com/baeldung/generics/Generics.java

@@ -1,30 +1,31 @@
-import java.util.ArrayList;
+package com.baeldung.generics;
+
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 public class Generics {
 
-	// definition of a generic method
-	public static <T> List<T> fromArrayToList(T[] a) {
-		List<T> list = new ArrayList<>();
-		Arrays.stream(a).forEach(list::add);
-		return list;
-	}
+    // definition of a generic method
+    public static <T> List<T> fromArrayToList(T[] a) {
+        return Arrays.stream(a).collect(Collectors.toList());
+    }
 
-	// example of a generic method that has Number as an upper bound for T
-	public static <T extends Number> List<T> fromArrayToListWithUpperBound(T[] a) {
-		List<T> list = new ArrayList<>();
-		Arrays.stream(a).forEach(list::add);
-		return list;
-	}
+    // definition of a generic method
+    public static <T, G> List<G> fromArrayToList(T[] a, Function<T, G> mapperFunction) {
+        return Arrays.stream(a).map(mapperFunction).collect(Collectors.toList());
+    }
 
-	// example of a generic method with a wild card, this method can be used
-	// with a list of any subtype of Building
-	public static boolean paintAllBuildings(List<? extends Building> buildings) {
-		for (Building building : buildings) {
-			building.paint();
-		}
-		return true;
-	}
+    // example of a generic method that has Number as an upper bound for T
+    public static <T extends Number> List<T> fromArrayToListWithUpperBound(T[] a) {
+        return Arrays.stream(a).collect(Collectors.toList());
+    }
+
+    // example of a generic method with a wild card, this method can be used
+    // with a list of any subtype of Building
+    public static void paintAllBuildings(List<? extends Building> buildings) {
+        buildings.forEach(Building::paint);
+    }
 
 }

core-java/src/main/java/com/baeldung/generics/House.java

@@ -0,0 +1,12 @@
+package com.baeldung.generics;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class House extends Building {
+    private static final Logger LOGGER = LoggerFactory.getLogger(House.class);
+
+    public void paint() {
+        LOGGER.info("Painting House");
+    }
+}

core-java/src/main/java/com/baeldung/generics/SubBuilding.java

@@ -1,4 +0,0 @@
-
-public class SubBuilding extends Building {
-
-}

core-java/src/main/java/com/baeldung/hashing/SHA256Hashing.java

@@ -1,6 +1,5 @@
 package com.baeldung.hashing;
 
-
 import com.google.common.hash.Hashing;
 import org.apache.commons.codec.digest.DigestUtils;
 import org.bouncycastle.util.encoders.Hex;
@@ -11,17 +10,14 @@ import java.security.NoSuchAlgorithmException;
 
 public class SHA256Hashing {
 
-    public static String HashWithJavaMessageDigest(final String originalString)
-            throws NoSuchAlgorithmException {
+    public static String HashWithJavaMessageDigest(final String originalString) throws NoSuchAlgorithmException {
         final MessageDigest digest = MessageDigest.getInstance("SHA-256");
-        final byte[] encodedhash = digest.digest(
-                originalString.getBytes(StandardCharsets.UTF_8));
+        final byte[] encodedhash = digest.digest(originalString.getBytes(StandardCharsets.UTF_8));
         return bytesToHex(encodedhash);
     }
 
     public static String HashWithGuava(final String originalString) {
-        final String sha256hex = Hashing.sha256().hashString(
-                originalString, StandardCharsets.UTF_8).toString();
+        final String sha256hex = Hashing.sha256().hashString(originalString, StandardCharsets.UTF_8).toString();
         return sha256hex;
     }
 
@@ -30,11 +26,9 @@ public class SHA256Hashing {
         return sha256hex;
     }
 
-    public static String HashWithBouncyCastle(final String originalString)
-            throws NoSuchAlgorithmException {
+    public static String HashWithBouncyCastle(final String originalString) throws NoSuchAlgorithmException {
         final MessageDigest digest = MessageDigest.getInstance("SHA-256");
-        final byte[] hash = digest.digest(
-                originalString.getBytes(StandardCharsets.UTF_8));
+        final byte[] hash = digest.digest(originalString.getBytes(StandardCharsets.UTF_8));
         final String sha256hex = new String(Hex.encode(hash));
         return sha256hex;
     }
@@ -43,7 +37,8 @@ public class SHA256Hashing {
         StringBuffer hexString = new StringBuffer();
         for (int i = 0; i < hash.length; i++) {
             String hex = Integer.toHexString(0xff & hash[i]);
-            if(hex.length() == 1) hexString.append('0');
+            if (hex.length() == 1)
+                hexString.append('0');
             hexString.append(hex);
         }
         return hexString.toString();

core-java/src/main/java/com/baeldung/java/map/MyKey.java

@@ -0,0 +1,59 @@
+package com.baeldung.java.map;
+
+public class MyKey {
+    private String name;
+    private int id;
+
+    public MyKey(int id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    @Override
+    public int hashCode() {
+        System.out.println("Calling hashCode()");
+        return id;
+    }
+
+    @Override
+    public String toString() {
+        return "MyKey [name=" + name + ", id=" + id + "]";
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        System.out.println("Calling equals() for key: " + obj);
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        MyKey other = (MyKey) obj;
+        if (id != other.id)
+            return false;
+        if (name == null) {
+            if (other.name != null)
+                return false;
+        } else if (!name.equals(other.name))
+            return false;
+        return true;
+    }
+
+}

core-java/src/main/java/com/baeldung/java/map/MyLinkedHashMap.java

@@ -0,0 +1,25 @@
+package com.baeldung.java.map;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+public class MyLinkedHashMap<K, V> extends LinkedHashMap<K, V> {
+
+    /**
+     * 
+     */
+    private static final long serialVersionUID = 1L;
+    private static final int MAX_ENTRIES = 5;
+    
+
+    public MyLinkedHashMap(int initialCapacity, float loadFactor, boolean accessOrder) {
+        super(initialCapacity, loadFactor, accessOrder);
+    }
+
+
+    @Override
+    protected boolean removeEldestEntry(Map.Entry eldest) {
+        return size() > MAX_ENTRIES;
+    }
+
+}

core-java/src/main/java/com/baeldung/java/networking/README.md

@@ -0,0 +1,5 @@
+### Relevant Articles:
+- [A Guide To UDP In Java](http://www.baeldung.com/udp-in-java)
+- [A Guide To HTTP Cookies In Java](http://www.baeldung.com/cookies-java)
+- [A Guide to the Java URL](http://www.baeldung.com/java-url)
+- [Working with Network Interfaces in Java](http://www.baeldung.com/java-network-interfaces)

core-java/src/main/java/com/baeldung/java/nio/selector/README.md

@@ -0,0 +1,2 @@
+###Relevant Articles:
+- [Introduction to the Java NIO Selector](http://www.baeldung.com/java-nio-selector)

core-java/src/main/java/com/baeldung/java/nio2/visitor/FileSearchExample.java

@@ -0,0 +1,56 @@
+package com.baeldung.java.nio2.visitor;
+
+import java.io.IOException;
+import java.nio.file.*;
+import java.nio.file.attribute.BasicFileAttributes;
+
+import static java.nio.file.FileVisitResult.CONTINUE;
+import static java.nio.file.FileVisitResult.TERMINATE;
+
+public class FileSearchExample implements FileVisitor<Path> {
+    private final String fileName;
+    private final Path startDir;
+
+    public FileSearchExample(String fileName, Path startingDir) {
+        this.fileName = fileName;
+        startDir = startingDir;
+    }
+
+    @Override
+    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
+        return CONTINUE;
+    }
+
+    @Override
+    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+        String fileName = file.getFileName().toString();
+        if (this.fileName.equals(fileName)) {
+            System.out.println("File found: " + file.toString());
+            return TERMINATE;
+        }
+        return CONTINUE;
+    }
+
+    @Override
+    public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException {
+        System.out.println("Failed to access file: " + file.toString());
+        return CONTINUE;
+    }
+
+    @Override
+    public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
+        boolean finishedSearch = Files.isSameFile(dir, startDir);
+        if (finishedSearch) {
+            System.out.println("File:" + fileName + " not found");
+            return TERMINATE;
+        }
+        return CONTINUE;
+    }
+
+    public static void main(String[] args) throws IOException {
+        Path startingDir = Paths.get("C:/Users/new/Desktop");
+        FileSearchExample crawler = new FileSearchExample("hibernate.txt", startingDir);
+        Files.walkFileTree(startingDir, crawler);
+    }
+
+}

core-java/src/main/java/com/baeldung/java/nio2/visitor/FileVisitorImpl.java

@@ -0,0 +1,30 @@
+package com.baeldung.java.nio2.visitor;
+
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.FileVisitor;
+import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
+
+public class FileVisitorImpl implements FileVisitor<Path> {
+
+    @Override
+    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
+        return null;
+    }
+
+    @Override
+    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
+        return null;
+    }
+
+    @Override
+    public FileVisitResult visitFileFailed(Path file, IOException exc) {
+        return null;
+    }
+
+    @Override
+    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
+        return null;
+    }
+}

core-java/src/main/java/com/baeldung/java/nio2/watcher/DirectoryWatcherExample.java

@@ -0,0 +1,25 @@
+package com.baeldung.java.nio2.watcher;
+
+import java.io.IOException;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardWatchEventKinds;
+import java.nio.file.WatchEvent;
+import java.nio.file.WatchKey;
+import java.nio.file.WatchService;
+
+public class DirectoryWatcherExample {
+    public static void main(String[] args) throws IOException, InterruptedException {
+        WatchService watchService = FileSystems.getDefault().newWatchService();
+        Path path = Paths.get(System.getProperty("user.home"));
+        path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY);
+        WatchKey key;
+        while ((key = watchService.take()) != null) {
+            for (WatchEvent<?> event : key.pollEvents()) {
+                System.out.println("Event kind:" + event.kind() + ". File affected: " + event.context() + ".");
+            }
+            key.reset();
+        }
+    }
+}

core-java/src/main/java/com/baeldung/jmx/Game.java

@@ -0,0 +1,24 @@
+package com.baeldung.jmx;
+
+public class Game implements GameMBean {
+
+    private String playerName;
+
+    @Override
+    public void playFootball(String clubName) {
+        System.out.println(this.playerName + " playing football for " + clubName);
+    }
+
+    @Override
+    public String getPlayerName() {
+        System.out.println("Return playerName " + this.playerName);
+        return playerName;
+    }
+
+    @Override
+    public void setPlayerName(String playerName) {
+        System.out.println("Set playerName to value " + playerName);
+        this.playerName = playerName;
+    }
+
+}

core-java/src/main/java/com/baeldung/jmx/GameMBean.java

@@ -0,0 +1,11 @@
+package com.baeldung.jmx;
+
+public interface GameMBean {
+
+    public void playFootball(String clubName);
+
+    public String getPlayerName();
+
+    public void setPlayerName(String playerName);
+
+}

core-java/src/main/java/com/baeldung/jmx/JMXTutorialMainlauncher.java

@@ -0,0 +1,37 @@
+package com.baeldung.jmx;
+
+import java.lang.management.ManagementFactory;
+import javax.management.InstanceAlreadyExistsException;
+import javax.management.MBeanRegistrationException;
+import javax.management.MBeanServer;
+import javax.management.MalformedObjectNameException;
+import javax.management.NotCompliantMBeanException;
+import javax.management.ObjectName;
+
+public class JMXTutorialMainlauncher {
+
+    public static void main(String[] args) {
+        // TODO Auto-generated method stub
+
+        System.out.println("This is basic JMX tutorial");
+        ObjectName objectName = null;
+        try {
+            objectName = new ObjectName("com.baeldung.tutorial:type=basic,name=game");
+        } catch (MalformedObjectNameException e) {
+            e.printStackTrace();
+        }
+        MBeanServer server = ManagementFactory.getPlatformMBeanServer();
+        Game gameObj = new Game();
+        try {
+            server.registerMBean(gameObj, objectName);
+        } catch (InstanceAlreadyExistsException | MBeanRegistrationException | NotCompliantMBeanException e) {
+            e.printStackTrace();
+        }
+        System.out.println("Registration for Game mbean with the platform server is successfull");
+        System.out.println("Please open jconsole to access Game mbean");
+        while (true) {
+            // to ensure application does not terminate
+        }
+    }
+
+}

core-java/src/main/java/com/baeldung/optional/Modem.java

@@ -0,0 +1,13 @@
+package com.baeldung.optional;
+
+public class Modem {
+    private Double price;
+
+    public Modem(Double price) {
+        this.price = price;
+    }
+
+    public Double getPrice() {
+        return price;
+    }
+}

core-java/src/main/java/com/baeldung/optional/Person.java

@@ -0,0 +1,39 @@
+package com.baeldung.optional;
+
+import java.util.Optional;
+
+public class Person {
+    private String name;
+    private int age;
+    private String password;
+
+    public Person(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public Optional<String> getName() {
+        return Optional.ofNullable(name);
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Optional<Integer> getAge() {
+        return Optional.ofNullable(age);
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public Optional<String> getPassword() {
+        return Optional.ofNullable(password);
+    }
+
+}

core-java/src/main/java/com/baeldung/printscreen/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [How to Print Screen in Java](http://www.baeldung.com/print-screen-in-java)

core-java/src/main/java/com/baeldung/scripting/Nashorn.java

@@ -0,0 +1,48 @@
+package com.baeldung.scripting;
+
+import javax.script.Bindings;
+import javax.script.Invocable;
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+
+public class Nashorn {
+    public static void main(String[] args) throws ScriptException, NoSuchMethodException {
+        ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
+
+        Object result = engine.eval(
+                "var greeting='hello world';" +
+                        "print(greeting);" +
+                        "greeting");
+
+        System.out.println(result);
+
+        Bindings bindings = engine.createBindings();
+        bindings.put("count", 3);
+        bindings.put("name", "baeldung");
+
+        String script = "var greeting='Hello ';" +
+                "for(var i=count;i>0;i--) { " +
+                "greeting+=name + ' '" +
+                "}" +
+                "greeting";
+
+        Object bindingsResult = engine.eval(script, bindings);
+        System.out.println(bindingsResult);
+
+        engine.eval("function composeGreeting(name) {" +
+                "return 'Hello ' + name" +
+                "}");
+        Invocable invocable = (Invocable) engine;
+
+        Object funcResult = invocable.invokeFunction("composeGreeting", "baeldung");
+        System.out.println(funcResult);
+
+        Object map = engine.eval("var HashMap = Java.type('java.util.HashMap');" +
+                "var map = new HashMap();" +
+                "map.put('hello', 'world');" +
+                "map");
+
+        System.out.println(map);
+    }
+}

core-java/src/main/java/com/baeldung/threadpool/ExitingExecutorServiceExample.java

@@ -16,10 +16,10 @@ public class ExitingExecutorServiceExample {
 
     public static void main(String... args) {
 
-        ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(5);
-        ExecutorService executorService = MoreExecutors.getExitingExecutorService(executor, 100, TimeUnit.MILLISECONDS);
+        final ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(5);
+        final ExecutorService executorService = MoreExecutors.getExitingExecutorService(executor, 100, TimeUnit.MILLISECONDS);
 
-        executorService.submit(() -> {
+        executorService.submit((Runnable) () -> {
             while (true) {
             }
         });

core-java/src/test/java/com/baeldung/algorithms/SimulatedAnnealingTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.algorithms;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.algorithms.annealing.SimulatedAnnealing;
+
+public class SimulatedAnnealingTest {
+
+    @Test
+    public void testSimulateAnnealing() {
+        Assert.assertTrue(SimulatedAnnealing.simulateAnnealing(10, 1000, 0.9) > 0);
+    }
+
+}

core-java/src/test/java/com/baeldung/collectors/Java8CollectorsUnitTest.java

@@ -42,96 +42,136 @@ public class Java8CollectorsUnitTest {
 
     @Test
     public void whenCollectingToList_shouldCollectToList() throws Exception {
-        final List<String> result = givenList.stream().collect(toList());
+        final List<String> result = givenList
+          .stream()
+          .collect(toList());
 
         assertThat(result).containsAll(givenList);
     }
 
     @Test
     public void whenCollectingToList_shouldCollectToSet() throws Exception {
-        final Set<String> result = givenList.stream().collect(toSet());
+        final Set<String> result = givenList
+          .stream()
+          .collect(toSet());
 
         assertThat(result).containsAll(givenList);
     }
 
     @Test
     public void whenCollectingToCollection_shouldCollectToCollection() throws Exception {
-        final List<String> result = givenList.stream().collect(toCollection(LinkedList::new));
+        final List<String> result = givenList
+          .stream()
+          .collect(toCollection(LinkedList::new));
 
-        assertThat(result).containsAll(givenList).isInstanceOf(LinkedList.class);
+        assertThat(result)
+          .containsAll(givenList)
+          .isInstanceOf(LinkedList.class);
     }
 
     @Test
     public void whenCollectingToImmutableCollection_shouldThrowException() throws Exception {
         assertThatThrownBy(() -> {
-            givenList.stream().collect(toCollection(ImmutableList::of));
+            givenList
+              .stream()
+              .collect(toCollection(ImmutableList::of));
         }).isInstanceOf(UnsupportedOperationException.class);
 
     }
 
     @Test
     public void whenCollectingToMap_shouldCollectToMap() throws Exception {
-        final Map<String, Integer> result = givenList.stream().collect(toMap(Function.identity(), String::length));
+        final Map<String, Integer> result = givenList
+          .stream()
+          .collect(toMap(Function.identity(), String::length));
 
-        assertThat(result).containsEntry("a", 1).containsEntry("bb", 2).containsEntry("ccc", 3).containsEntry("dd", 2);
+        assertThat(result)
+          .containsEntry("a", 1)
+          .containsEntry("bb", 2)
+          .containsEntry("ccc", 3)
+          .containsEntry("dd", 2);
     }
 
     @Test
     public void whenCollectingToMap_shouldCollectToMapMerging() throws Exception {
-        final Map<String, Integer> result = givenList.stream().collect(toMap(Function.identity(), String::length, (i1, i2) -> i1));
+        final Map<String, Integer> result = givenList
+          .stream()
+          .collect(toMap(Function.identity(), String::length, (i1, i2) -> i1));
 
-        assertThat(result).containsEntry("a", 1).containsEntry("bb", 2).containsEntry("ccc", 3).containsEntry("dd", 2);
+        assertThat(result)
+          .containsEntry("a", 1)
+          .containsEntry("bb", 2)
+          .containsEntry("ccc", 3)
+          .containsEntry("dd", 2);
     }
 
     @Test
     public void whenCollectingAndThen_shouldCollect() throws Exception {
-        final List<String> result = givenList.stream().collect(collectingAndThen(toList(), ImmutableList::copyOf));
+        final List<String> result = givenList
+          .stream()
+          .collect(collectingAndThen(toList(), ImmutableList::copyOf));
 
-        assertThat(result).containsAll(givenList).isInstanceOf(ImmutableList.class);
+        assertThat(result)
+          .containsAll(givenList)
+          .isInstanceOf(ImmutableList.class);
     }
 
     @Test
     public void whenJoining_shouldJoin() throws Exception {
-        final String result = givenList.stream().collect(joining());
+        final String result = givenList
+          .stream()
+          .collect(joining());
 
         assertThat(result).isEqualTo("abbcccdd");
     }
 
     @Test
     public void whenJoiningWithSeparator_shouldJoinWithSeparator() throws Exception {
-        final String result = givenList.stream().collect(joining(" "));
+        final String result = givenList
+          .stream()
+          .collect(joining(" "));
 
         assertThat(result).isEqualTo("a bb ccc dd");
     }
 
     @Test
     public void whenJoiningWithSeparatorAndPrefixAndPostfix_shouldJoinWithSeparatorPrePost() throws Exception {
-        final String result = givenList.stream().collect(joining(" ", "PRE-", "-POST"));
+        final String result = givenList
+          .stream()
+          .collect(joining(" ", "PRE-", "-POST"));
 
         assertThat(result).isEqualTo("PRE-a bb ccc dd-POST");
     }
 
     @Test
     public void whenPartitioningBy_shouldPartition() throws Exception {
-        final Map<Boolean, List<String>> result = givenList.stream().collect(partitioningBy(s -> s.length() > 2));
+        final Map<Boolean, List<String>> result = givenList
+          .stream()
+          .collect(partitioningBy(s -> s.length() > 2));
 
-        assertThat(result).containsKeys(true, false).satisfies(booleanListMap -> {
-            assertThat(booleanListMap.get(true)).contains("ccc");
+        assertThat(result)
+          .containsKeys(true, false)
+          .satisfies(booleanListMap -> {
+              assertThat(booleanListMap.get(true)).contains("ccc");
 
-            assertThat(booleanListMap.get(false)).contains("a", "bb", "dd");
-        });
+              assertThat(booleanListMap.get(false)).contains("a", "bb", "dd");
+          });
     }
 
     @Test
     public void whenCounting_shouldCount() throws Exception {
-        final Long result = givenList.stream().collect(counting());
+        final Long result = givenList
+          .stream()
+          .collect(counting());
 
         assertThat(result).isEqualTo(4);
     }
 
     @Test
     public void whenSummarizing_shouldSummarize() throws Exception {
-        final DoubleSummaryStatistics result = givenList.stream().collect(summarizingDouble(String::length));
+        final DoubleSummaryStatistics result = givenList
+          .stream()
+          .collect(summarizingDouble(String::length));
 
         assertThat(result.getAverage()).isEqualTo(2);
         assertThat(result.getCount()).isEqualTo(4);
@@ -142,37 +182,55 @@ public class Java8CollectorsUnitTest {
 
     @Test
     public void whenAveraging_shouldAverage() throws Exception {
-        final Double result = givenList.stream().collect(averagingDouble(String::length));
+        final Double result = givenList
+          .stream()
+          .collect(averagingDouble(String::length));
 
         assertThat(result).isEqualTo(2);
     }
 
     @Test
     public void whenSumming_shouldSum() throws Exception {
-        final Double result = givenList.stream().collect(summingDouble(String::length));
+        final Double result = givenList
+          .stream()
+          .filter(i -> true)
+          .collect(summingDouble(String::length));
 
         assertThat(result).isEqualTo(8);
     }
 
     @Test
     public void whenMaxingBy_shouldMaxBy() throws Exception {
-        final Optional<String> result = givenList.stream().collect(maxBy(Comparator.naturalOrder()));
+        final Optional<String> result = givenList
+          .stream()
+          .collect(maxBy(Comparator.naturalOrder()));
 
-        assertThat(result).isPresent().hasValue("dd");
+        assertThat(result)
+          .isPresent()
+          .hasValue("dd");
     }
 
     @Test
     public void whenGroupingBy_shouldGroupBy() throws Exception {
-        final Map<Integer, Set<String>> result = givenList.stream().collect(groupingBy(String::length, toSet()));
+        final Map<Integer, Set<String>> result = givenList
+          .stream()
+          .collect(groupingBy(String::length, toSet()));
 
-        assertThat(result).containsEntry(1, newHashSet("a")).containsEntry(2, newHashSet("bb", "dd")).containsEntry(3, newHashSet("ccc"));
+        assertThat(result)
+          .containsEntry(1, newHashSet("a"))
+          .containsEntry(2, newHashSet("bb", "dd"))
+          .containsEntry(3, newHashSet("ccc"));
     }
 
     @Test
     public void whenCreatingCustomCollector_shouldCollect() throws Exception {
-        final ImmutableSet<String> result = givenList.stream().collect(toImmutableSet());
+        final ImmutableSet<String> result = givenList
+          .stream()
+          .collect(toImmutableSet());
 
-        assertThat(result).isInstanceOf(ImmutableSet.class).contains("a", "bb", "ccc", "dd");
+        assertThat(result)
+          .isInstanceOf(ImmutableSet.class)
+          .contains("a", "bb", "ccc", "dd");
 
     }
 

core-java/src/test/java/com/baeldung/encoderdecoder/EncoderDecoderUnitTest.java

@@ -7,20 +7,20 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.UnsupportedEncodingException;
-import java.net.URL;
-import java.net.URLDecoder;
-import java.net.URLEncoder;
+import java.net.*;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 
 import static java.util.stream.Collectors.joining;
+import static org.hamcrest.CoreMatchers.*;
 
 public class EncoderDecoderUnitTest {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(EncoderDecoderUnitTest.class);
     private static final String testUrl = "http://www.baeldung.com?key1=value+1&key2=value%40%21%242&key3=value%253";
+    private static final String testUrlWithPath = "http://www.baeldung.com/path+1?key1=value+1&key2=value%40%21%242&key3=value%253";
 
     private String encodeValue(String value) {
         String encoded = null;
@@ -46,9 +46,9 @@ public class EncoderDecoderUnitTest {
     public void givenURL_whenAnalyze_thenCorrect() throws Exception {
         URL url = new URL(testUrl);
 
-        Assert.assertThat(url.getProtocol(), CoreMatchers.is("http"));
-        Assert.assertThat(url.getHost(), CoreMatchers.is("www.baeldung.com"));
-        Assert.assertThat(url.getQuery(), CoreMatchers.is("key1=value+1&key2=value%40%21%242&key3=value%253"));
+        Assert.assertThat(url.getProtocol(), is("http"));
+        Assert.assertThat(url.getHost(), is("www.baeldung.com"));
+        Assert.assertThat(url.getQuery(), is("key1=value+1&key2=value%40%21%242&key3=value%253"));
     }
 
     @Test
@@ -60,7 +60,7 @@ public class EncoderDecoderUnitTest {
 
         String encodedURL = requestParams.keySet().stream().map(key -> key + "=" + encodeValue(requestParams.get(key))).collect(joining("&", "http://www.baeldung.com?", ""));
 
-        Assert.assertThat(testUrl, CoreMatchers.is(encodedURL));
+        Assert.assertThat(testUrl, is(encodedURL));
     }
 
     @Test
@@ -74,4 +74,35 @@ public class EncoderDecoderUnitTest {
         Assert.assertEquals("http://www.baeldung.com?key1=value 1&key2=value@!$2&key3=value%3", url.getProtocol() + "://" + url.getHost() + "?" + decodedQuery);
     }
 
+    private String encodePath(String path) {
+        try {
+            path = new URI(null, null, path, null).getPath();
+        } catch (URISyntaxException e) {
+            LOGGER.error("Error encoding parameter {}", e.getMessage(), e);
+        }
+        return path;
+    }
+
+    @Test
+    public void givenPath_thenEncodeDecodePath() throws URISyntaxException {
+        URI uri = new URI(null, null, "/Path 1/Path+2", null);
+
+        Assert.assertEquals("/Path 1/Path+2", uri.getPath());
+        Assert.assertEquals("/Path%201/Path+2", uri.getRawPath());
+    }
+
+    @Test
+    public void givenPathAndRequestParam_whenUTF8Scheme_thenEncode() throws Exception {
+        Map<String, String> requestParams = new HashMap<>();
+        requestParams.put("key1", "value 1");
+        requestParams.put("key2", "value@!$2");
+        requestParams.put("key3", "value%3");
+
+        String path = "path+1";
+
+        String encodedURL = requestParams.keySet().stream().map(key -> key + "=" + encodeValue(requestParams.get(key))).collect(joining("&", "http://www.baeldung.com/" + encodePath(path) + "?", ""));
+
+        Assert.assertThat(testUrlWithPath, is(encodedURL));
+    }
+
 }

core-java/src/test/java/com/baeldung/file/FileOperationsUnitTest.java

@@ -1,11 +1,12 @@
 package com.baeldung.file;
 
-import java.io.BufferedReader;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
+import org.apache.commons.io.FileUtils;
+import org.hamcrest.CoreMatchers;
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.*;
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLConnection;
@@ -14,12 +15,6 @@ import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.stream.Stream;
 
-import org.apache.commons.io.FileUtils;
-import org.hamcrest.CoreMatchers;
-import org.hamcrest.Matchers;
-import org.junit.Assert;
-import org.junit.Test;
-
 public class FileOperationsUnitTest {
 
     @Test
@@ -58,9 +53,9 @@ public class FileOperationsUnitTest {
 
     @Test
     public void givenURLName_whenUsingURL_thenFileData() throws IOException {
-        String expectedData = "Baeldung";
+        String expectedData = "Example Domain";
 
-        URL urlObject = new URL("http://www.baeldung.com/");
+        URL urlObject = new URL("http://www.example.com/");
 
         URLConnection urlConnection = urlObject.openConnection();
 

core-java/src/test/java/com/baeldung/generics/GenericsTest.java

@@ -1,55 +1,69 @@
-import static org.hamcrest.CoreMatchers.hasItems;
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.junit.Assert.assertTrue;
+package com.baeldung.generics;
+
+import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.List;
 
-import org.junit.Test;
+import static org.hamcrest.CoreMatchers.hasItems;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.fail;
 
 public class GenericsTest {
 
-	// testing the generic method with Integer
-	@Test
-	public void givenArrayOfIntegers_thanListOfIntegersReturnedOK() {
-		Integer[] intArray = { 1, 2, 3, 4, 5 };
-		List<Integer> list = Generics.fromArrayToList(intArray);
+    // testing the generic method with Integer
+    @Test
+    public void givenArrayOfIntegers_thanListOfIntegersReturnedOK() {
+        Integer[] intArray = { 1, 2, 3, 4, 5 };
+        List<Integer> list = Generics.fromArrayToList(intArray);
 
-		assertThat(list, hasItems(intArray));
-	}
+        assertThat(list, hasItems(intArray));
+    }
 
-	// testing the generic method with String
-	@Test
-	public void givenArrayOfStrings_thanListOfStringsReturnedOK() {
-		String[] stringArray = { "hello1", "hello2", "hello3", "hello4", "hello5" };
-		List<String> list = Generics.fromArrayToList(stringArray);
+    // testing the generic method with Integer and String type
+    @Test
+    public void givenArrayOfIntegers_thanListOfStringReturnedOK() {
+        Integer[] intArray = { 1, 2, 3, 4, 5 };
+        List<String> stringList = Generics.fromArrayToList(intArray, Object::toString);
+        assertThat(stringList, hasItems("1", "2", "3", "4", "5"));
+    }
 
-		assertThat(list, hasItems(stringArray));
-	}
+    // testing the generic method with String
+    @Test
+    public void givenArrayOfStrings_thanListOfStringsReturnedOK() {
+        String[] stringArray = { "hello1", "hello2", "hello3", "hello4", "hello5" };
+        List<String> list = Generics.fromArrayToList(stringArray);
 
-	// testing the generic method with Number as upper bound with Integer
-	// if we test fromArrayToListWithUpperBound with any type that doesn't
-	// extend Number it will fail to compile
-	@Test
-	public void givenArrayOfIntegersAndNumberUpperBound_thanListOfIntegersReturnedOK() {
-		Integer[] intArray = { 1, 2, 3, 4, 5 };
-		List<Integer> list = Generics.fromArrayToListWithUpperBound(intArray);
+        assertThat(list, hasItems(stringArray));
+    }
 
-		assertThat(list, hasItems(intArray));
-	}
+    // testing the generic method with Number as upper bound with Integer
+    // if we test fromArrayToListWithUpperBound with any type that doesn't
+    // extend Number it will fail to compile
+    @Test
+    public void givenArrayOfIntegersAndNumberUpperBound_thanListOfIntegersReturnedOK() {
+        Integer[] intArray = { 1, 2, 3, 4, 5 };
+        List<Integer> list = Generics.fromArrayToListWithUpperBound(intArray);
 
-	// testing paintAllBuildings method with a subtype of Building, the method
-	// will work with all subtypes of Building
-	@Test
-	public void givenSubTypeOfAwildCardBoundedGenericMethod() {
+        assertThat(list, hasItems(intArray));
+    }
 
-		List<SubBuilding> subBuildingsList = new ArrayList<>();
-		subBuildingsList.add(new SubBuilding());
-		subBuildingsList.add(new SubBuilding());
+    // testing paintAllBuildings method with a subtype of Building, the method
+    // will work with all subtypes of Building
+    @Test
+    public void givenSubTypeOfWildCardBoundedGenericType_thanPaintingOK() {
+        try {
+            List<Building> subBuildingsList = new ArrayList<>();
+            subBuildingsList.add(new Building());
+            subBuildingsList.add(new House());
 
-		boolean result = Generics.paintAllBuildings(subBuildingsList);
-		assertTrue(result);
-
-	}
+            // prints
+            // Painting Building
+            // Painting House
+            Generics.paintAllBuildings(subBuildingsList);
+        } catch (Exception e) {
+            fail();
+        }
+    }
 
 }

core-java/src/test/java/com/baeldung/grep/GrepWithUnix4JTest.java

@@ -0,0 +1,55 @@
+package com.baeldung.grep;
+
+import java.io.File;
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.unix4j.Unix4j;
+import static org.unix4j.Unix4j.*;
+import static org.junit.Assert.assertEquals;
+import org.unix4j.line.Line;
+import static org.unix4j.unix.Grep.*;
+import static org.unix4j.unix.cut.CutOption.*;
+
+public class GrepWithUnix4JTest {
+
+    private File fileToGrep;
+
+    @Before
+    public void init() {
+        final String separator = File.separator;
+        final String filePath = String.join(separator, new String[] { "src", "test", "resources", "dictionary.in" });
+        fileToGrep = new File(filePath);
+    }
+
+    @Test
+    public void whenGrepWithSimpleString_thenCorrect() {
+        int expectedLineCount = 4;
+
+        // grep "NINETEEN" dictionary.txt
+        List<Line> lines = Unix4j.grep("NINETEEN", fileToGrep).toLineList();
+
+        assertEquals(expectedLineCount, lines.size());
+    }
+
+    @Test
+    public void whenInverseGrepWithSimpleString_thenCorrect() {
+        int expectedLineCount = 178687;
+
+        // grep -v "NINETEEN" dictionary.txt
+        List<Line> lines = grep(Options.v, "NINETEEN", fileToGrep).toLineList();
+
+        assertEquals(expectedLineCount, lines.size());
+    }
+
+    @Test
+    public void whenGrepWithRegex_thenCorrect() {
+        int expectedLineCount = 151;
+
+        // grep -c ".*?NINE.*?" dictionary.txt
+        String patternCount = grep(Options.c, ".*?NINE.*?", fileToGrep).cut(fields, ":", 1).toStringResult();
+
+        assertEquals(expectedLineCount, Integer.parseInt(patternCount));
+    }
+}

core-java/src/test/java/com/baeldung/hashing/SHA256HashingTest.java

@@ -4,12 +4,10 @@ import org.junit.Test;
 
 import static org.junit.Assert.*;
 
-
 public class SHA256HashingTest {
 
     private static String originalValue = "abc123";
-    private static String hashedValue =
-            "6ca13d52ca70c883e0f0bb101e425a89e8624de51db2d2392593af6a84118090";
+    private static String hashedValue = "6ca13d52ca70c883e0f0bb101e425a89e8624de51db2d2392593af6a84118090";
 
     @Test
     public void testHashWithJavaMessageDigest() throws Exception {

core-java/src/test/java/com/baeldung/hexToAscii/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [Convert Hex to ASCII in Java](http://www.baeldung.com/java-convert-hex-to-ascii)

core-java/src/test/java/com/baeldung/java/conversion/README.md

@@ -0,0 +1,2 @@
+Relevant Articles:
+- [Java String Conversions](http://www.baeldung.com/java-string-conversions)

core-java/src/test/java/com/baeldung/java/conversion/StringConversionTest.java

@@ -119,8 +119,7 @@ public class StringConversionTest {
         int afterConvCalendarDay = 03;
         Month afterConvCalendarMonth = Month.DECEMBER;
         int afterConvCalendarYear = 2007;
-        LocalDateTime afterConvDate 
-          = new UseLocalDateTime().getLocalDateTimeUsingParseMethod(str);
+        LocalDateTime afterConvDate = new UseLocalDateTime().getLocalDateTimeUsingParseMethod(str);
 
         assertEquals(afterConvDate.getDayOfMonth(), afterConvCalendarDay);
         assertEquals(afterConvDate.getMonth(), afterConvCalendarMonth);

core-java/src/test/java/com/baeldung/java/map/MapTest.java

@@ -0,0 +1,350 @@
+package com.baeldung.java.map;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.ConcurrentModificationException;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.TreeMap;
+
+import org.junit.Test;
+
+public class MapTest {
+    @Test
+    public void givenHashMap_whenRetrievesKeyset_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", "baeldung");
+        map.put("type", "blog");
+
+        Set<String> keys = map.keySet();
+
+        assertEquals(2, keys.size());
+        assertTrue(keys.contains("name"));
+        assertTrue(keys.contains("type"));
+    }
+
+    @Test
+    public void givenHashMap_whenRetrievesValues_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", "baeldung");
+        map.put("type", "blog");
+
+        Collection<String> values = map.values();
+
+        assertEquals(2, values.size());
+        assertTrue(values.contains("baeldung"));
+        assertTrue(values.contains("blog"));
+    }
+
+    @Test
+    public void givenHashMap_whenRetrievesEntries_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", "baeldung");
+        map.put("type", "blog");
+
+        Set<Entry<String, String>> entries = map.entrySet();
+
+        assertEquals(2, entries.size());
+        for (Entry<String, String> e : entries) {
+            String key = e.getKey();
+            String val = e.getValue();
+            assertTrue(key.equals("name") || key.equals("type"));
+            assertTrue(val.equals("baeldung") || val.equals("blog"));
+        }
+    }
+
+    @Test
+    public void givenKeySet_whenChangeReflectsInMap_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", "baeldung");
+        map.put("type", "blog");
+
+        assertEquals(2, map.size());
+
+        Set<String> keys = map.keySet();
+
+        keys.remove("name");
+        assertEquals(1, map.size());
+    }
+
+    @Test(expected = ConcurrentModificationException.class)
+    public void givenIterator_whenFailsFastOnModification_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", "baeldung");
+        map.put("type", "blog");
+
+        Set<String> keys = map.keySet();
+        Iterator<String> it = keys.iterator();
+        map.remove("type");
+        while (it.hasNext()) {
+            String key = it.next();
+        }
+    }
+
+    public void givenIterator_whenRemoveWorks_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", "baeldung");
+        map.put("type", "blog");
+
+        Set<String> keys = map.keySet();
+        Iterator<String> it = keys.iterator();
+        while (it.hasNext()) {
+            it.next();
+            it.remove();
+        }
+        assertEquals(0, map.size());
+    }
+
+    @Test
+    public void whenHashCodeIsCalledOnPut_thenCorrect() {
+        MyKey key = new MyKey(1, "name");
+        Map<MyKey, String> map = new HashMap<>();
+        map.put(key, "val");
+    }
+
+    @Test
+    public void whenHashCodeIsCalledOnGet_thenCorrect() {
+        MyKey key = new MyKey(1, "name");
+        Map<MyKey, String> map = new HashMap<>();
+        map.put(key, "val");
+        map.get(key);
+    }
+
+    @Test
+    public void whenGetWorks_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("key", "val");
+
+        String val = map.get("key");
+
+        assertEquals("val", val);
+    }
+
+    @Test
+    public void givenNewKey_whenPutReturnsNull_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+
+        String rtnVal = map.put("key1", "val1");
+
+        assertNull(rtnVal);
+    }
+
+    @Test
+    public void givenUnmappedKey_whenGetReturnsNull_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+
+        String rtnVal = map.get("key1");
+
+        assertNull(rtnVal);
+    }
+
+    @Test
+    public void givenNullVal_whenPutReturnsNull_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+
+        String rtnVal = map.put("key1", null);
+
+        assertNull(rtnVal);
+    }
+
+    @Test
+    public void givenNullKeyAndVal_whenAccepts_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+
+        map.put(null, null);
+    }
+
+    @Test
+    public void givenNullVal_whenRetrieves_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("key", null);
+
+        String val = map.get("key");
+
+        assertNull(val);
+    }
+
+    @Test
+    public void whenContainsDistinguishesNullValues_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+
+        String val1 = map.get("key");
+        boolean valPresent = map.containsKey("key");
+
+        assertNull(val1);
+        assertFalse(valPresent);
+
+        map.put("key", null);
+        String val = map.get("key");
+        valPresent = map.containsKey("key");
+
+        assertNull(val);
+        assertTrue(valPresent);
+
+    }
+
+    @Test
+    public void whenPutReturnsPrevValue_thenCorrect() {
+        Map<String, String> map = new HashMap<>();
+        map.put("key1", "val1");
+        String rtnVal = map.put("key1", "val2");
+
+        assertEquals("val1", rtnVal);
+    }
+
+
+
+    @Test
+    public void whenCallsEqualsOnCollision_thenCorrect() {
+        HashMap<MyKey, String> map = new HashMap<>();
+        MyKey k1 = new MyKey(1, "firstKey");
+        MyKey k2 = new MyKey(2, "secondKey");
+        MyKey k3 = new MyKey(2, "thirdKey");
+
+        System.out.println("storing value for k1");
+        map.put(k1, "firstValue");
+
+        System.out.println("storing value for k2");
+        map.put(k2, "secondValue");
+
+        System.out.println("storing value for k3");
+        map.put(k3, "thirdValue");
+
+        System.out.println("retrieving value for k1");
+        String v1 = map.get(k1);
+
+        System.out.println("retrieving value for k2");
+        String v2 = map.get(k2);
+
+        System.out.println("retrieving value for k3");
+        String v3 = map.get(k3);
+
+        assertEquals("firstValue", v1);
+        assertEquals("secondValue", v2);
+        assertEquals("thirdValue", v3);
+
+    }
+
+    @Test
+    public void givenLinkedHashMap_whenGetsOrderedKeyset_thenCorrect() {
+        LinkedHashMap<Integer, String> map = new LinkedHashMap<>();
+        map.put(1, null);
+        map.put(2, null);
+        map.put(3, null);
+        map.put(4, null);
+        map.put(5, null);
+        Set<Integer> keys = map.keySet();
+        Integer[] arr = keys.toArray(new Integer[0]);
+        for (int i = 0; i < arr.length; i++) {
+            assertEquals(new Integer(i + 1), arr[i]);
+
+        }
+    }
+
+    @Test
+    public void givenLinkedHashMap_whenAccessOrderWorks_thenCorrect() {
+        LinkedHashMap<Integer, String> map = new LinkedHashMap<>(16, .75f, true);
+        map.put(1, null);
+        map.put(2, null);
+        map.put(3, null);
+        map.put(4, null);
+        map.put(5, null);
+        Set<Integer> keys = map.keySet();
+        assertEquals("[1, 2, 3, 4, 5]", keys.toString());
+        map.get(4);
+        assertEquals("[1, 2, 3, 5, 4]", keys.toString());
+        map.get(1);
+        assertEquals("[2, 3, 5, 4, 1]", keys.toString());
+        map.get(3);
+        assertEquals("[2, 5, 4, 1, 3]", keys.toString());
+    }
+
+    @Test
+    public void givenLinkedHashMap_whenRemovesEldestEntry_thenCorrect() {
+        LinkedHashMap<Integer, String> map = new MyLinkedHashMap<>(16, .75f, true);
+        map.put(1, null);
+        map.put(2, null);
+        map.put(3, null);
+        map.put(4, null);
+        map.put(5, null);
+        Set<Integer> keys = map.keySet();
+        assertEquals("[1, 2, 3, 4, 5]", keys.toString());
+        map.put(6, null);
+        assertEquals("[2, 3, 4, 5, 6]", keys.toString());
+        map.put(7, null);
+        assertEquals("[3, 4, 5, 6, 7]", keys.toString());
+        map.put(8, null);
+        assertEquals("[4, 5, 6, 7, 8]", keys.toString());
+    }
+
+    @Test
+    public void givenTreeMap_whenOrdersEntriesNaturally_thenCorrect() {
+        TreeMap<Integer, String> map = new TreeMap<>();
+        map.put(3, "val");
+        map.put(2, "val");
+        map.put(1, "val");
+        map.put(5, "val");
+        map.put(4, "val");
+        assertEquals("[1, 2, 3, 4, 5]", map.keySet().toString());
+    }
+
+    @Test
+    public void givenTreeMap_whenOrdersEntriesNaturally_thenCorrect2() {
+        TreeMap<String, String> map = new TreeMap<>();
+        map.put("c", "val");
+        map.put("b", "val");
+        map.put("a", "val");
+        map.put("e", "val");
+        map.put("d", "val");
+
+        assertEquals("[a, b, c, d, e]", map.keySet().toString());
+    }
+
+    @Test
+    public void givenTreeMap_whenOrdersEntriesByComparator_thenCorrect() {
+        TreeMap<Integer, String> map = new TreeMap<>(new Comparator<Integer>() {
+
+            @Override
+            public int compare(Integer o1, Integer o2) {
+                return o2 - o1;
+            }
+        });
+        map.put(3, "val");
+        map.put(2, "val");
+        map.put(1, "val");
+        map.put(5, "val");
+        map.put(4, "val");
+
+        assertEquals("[5, 4, 3, 2, 1]", map.keySet().toString());
+    }
+
+    @Test
+    public void givenTreeMap_whenPerformsQueries_thenCorrect() {
+        TreeMap<Integer, String> map = new TreeMap<>();
+        map.put(3, "val");
+        map.put(2, "val");
+        map.put(1, "val");
+        map.put(5, "val");
+        map.put(4, "val");
+        
+        Integer highestKey = map.lastKey();
+        Integer lowestKey = map.firstKey();
+        Set<Integer> keysLessThan3 = map.headMap(3).keySet();
+        Set<Integer> keysGreaterThanEqTo3 = map.tailMap(3).keySet();
+
+        assertEquals(new Integer(5), highestKey);
+        assertEquals(new Integer(1), lowestKey);
+        assertEquals("[1, 2]", keysLessThan3.toString());
+        assertEquals("[3, 4, 5]", keysGreaterThanEqTo3.toString());
+    }
+
+}

core-java/src/test/java/com/baeldung/java/nio2/FileTest.java

@@ -1,64 +1,72 @@
 package com.baeldung.java.nio2;
 
+import org.apache.commons.io.FileUtils;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.*;
+import java.util.UUID;
+
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-import java.io.IOException;
-import java.nio.file.DirectoryNotEmptyException;
-import java.nio.file.FileAlreadyExistsException;
-import java.nio.file.Files;
-import java.nio.file.NoSuchFileException;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-import java.nio.file.StandardCopyOption;
-import java.util.UUID;
-
-import org.junit.Test;
-
 public class FileTest {
-    private static final String HOME = System.getProperty("user.home");
+    private static final String TEMP_DIR = String.format("%s/temp%s", System.getProperty("user.home"), UUID.randomUUID().toString());
+
+    @BeforeClass
+    public static void setup() throws IOException {
+        Files.createDirectory(Paths.get(TEMP_DIR));
+    }
+
+    @AfterClass
+    public static void cleanup() throws IOException {
+        FileUtils.deleteDirectory(new File(TEMP_DIR));
+    }
 
     // checking file or dir
     @Test
     public void givenExistentPath_whenConfirmsFileExists_thenCorrect() {
-        Path p = Paths.get(HOME);
+        Path p = Paths.get(TEMP_DIR);
         assertTrue(Files.exists(p));
     }
 
     @Test
     public void givenNonexistentPath_whenConfirmsFileNotExists_thenCorrect() {
-        Path p = Paths.get(HOME + "/inexistent_file.txt");
+        Path p = Paths.get(TEMP_DIR + "/inexistent_file.txt");
         assertTrue(Files.notExists(p));
     }
 
     @Test
     public void givenDirPath_whenConfirmsNotRegularFile_thenCorrect() {
-        Path p = Paths.get(HOME);
+        Path p = Paths.get(TEMP_DIR);
         assertFalse(Files.isRegularFile(p));
     }
 
     @Test
     public void givenExistentDirPath_whenConfirmsReadable_thenCorrect() {
-        Path p = Paths.get(HOME);
+        Path p = Paths.get(TEMP_DIR);
         assertTrue(Files.isReadable(p));
     }
 
     @Test
     public void givenExistentDirPath_whenConfirmsWritable_thenCorrect() {
-        Path p = Paths.get(HOME);
+        Path p = Paths.get(System.getProperty("user.home"));
         assertTrue(Files.isWritable(p));
     }
 
     @Test
     public void givenExistentDirPath_whenConfirmsExecutable_thenCorrect() {
-        Path p = Paths.get(HOME);
+        Path p = Paths.get(System.getProperty("user.home"));
         assertTrue(Files.isExecutable(p));
     }
 
     @Test
     public void givenSameFilePaths_whenConfirmsIsSame_thenCorrect() throws IOException {
-        Path p1 = Paths.get(HOME);
-        Path p2 = Paths.get(HOME);
+        Path p1 = Paths.get(TEMP_DIR);
+        Path p2 = Paths.get(TEMP_DIR);
         assertTrue(Files.isSameFile(p1, p2));
     }
 
@@ -67,7 +75,7 @@ public class FileTest {
     @Test
     public void givenFilePath_whenCreatesNewFile_thenCorrect() throws IOException {
         String fileName = "myfile_" + UUID.randomUUID().toString() + ".txt";
-        Path p = Paths.get(HOME + "/" + fileName);
+        Path p = Paths.get(TEMP_DIR + "/" + fileName);
         assertFalse(Files.exists(p));
         Files.createFile(p);
         assertTrue(Files.exists(p));
@@ -77,7 +85,7 @@ public class FileTest {
     @Test
     public void givenDirPath_whenCreatesNewDir_thenCorrect() throws IOException {
         String dirName = "myDir_" + UUID.randomUUID().toString();
-        Path p = Paths.get(HOME + "/" + dirName);
+        Path p = Paths.get(TEMP_DIR + "/" + dirName);
         assertFalse(Files.exists(p));
         Files.createDirectory(p);
         assertTrue(Files.exists(p));
@@ -89,7 +97,7 @@ public class FileTest {
     @Test(expected = NoSuchFileException.class)
     public void givenDirPath_whenFailsToCreateRecursively_thenCorrect() throws IOException {
         String dirName = "myDir_" + UUID.randomUUID().toString() + "/subdir";
-        Path p = Paths.get(HOME + "/" + dirName);
+        Path p = Paths.get(TEMP_DIR + "/" + dirName);
         assertFalse(Files.exists(p));
         Files.createDirectory(p);
 
@@ -97,7 +105,7 @@ public class FileTest {
 
     @Test
     public void givenDirPath_whenCreatesRecursively_thenCorrect() throws IOException {
-        Path dir = Paths.get(HOME + "/myDir_" + UUID.randomUUID().toString());
+        Path dir = Paths.get(TEMP_DIR + "/myDir_" + UUID.randomUUID().toString());
         Path subdir = dir.resolve("subdir");
         assertFalse(Files.exists(dir));
         assertFalse(Files.exists(subdir));
@@ -110,7 +118,7 @@ public class FileTest {
     public void givenFilePath_whenCreatesTempFile_thenCorrect() throws IOException {
         String prefix = "log_";
         String suffix = ".txt";
-        Path p = Paths.get(HOME + "/");
+        Path p = Paths.get(TEMP_DIR + "/");
         p = Files.createTempFile(p, prefix, suffix);
         // like log_8821081429012075286.txt
         assertTrue(Files.exists(p));
@@ -119,7 +127,7 @@ public class FileTest {
 
     @Test
     public void givenPath_whenCreatesTempFileWithDefaults_thenCorrect() throws IOException {
-        Path p = Paths.get(HOME + "/");
+        Path p = Paths.get(TEMP_DIR + "/");
         p = Files.createTempFile(p, null, null);
         // like 8600179353689423985.tmp
         assertTrue(Files.exists(p));
@@ -136,7 +144,7 @@ public class FileTest {
     // delete file
     @Test
     public void givenPath_whenDeletes_thenCorrect() throws IOException {
-        Path p = Paths.get(HOME + "/fileToDelete.txt");
+        Path p = Paths.get(TEMP_DIR + "/fileToDelete.txt");
         assertFalse(Files.exists(p));
         Files.createFile(p);
         assertTrue(Files.exists(p));
@@ -147,7 +155,7 @@ public class FileTest {
 
     @Test(expected = DirectoryNotEmptyException.class)
     public void givenPath_whenFailsToDeleteNonEmptyDir_thenCorrect() throws IOException {
-        Path dir = Paths.get(HOME + "/emptyDir" + UUID.randomUUID().toString());
+        Path dir = Paths.get(TEMP_DIR + "/emptyDir" + UUID.randomUUID().toString());
         Files.createDirectory(dir);
         assertTrue(Files.exists(dir));
         Path file = dir.resolve("file.txt");
@@ -160,7 +168,7 @@ public class FileTest {
 
     @Test(expected = NoSuchFileException.class)
     public void givenInexistentFile_whenDeleteFails_thenCorrect() throws IOException {
-        Path p = Paths.get(HOME + "/inexistentFile.txt");
+        Path p = Paths.get(TEMP_DIR + "/inexistentFile.txt");
         assertFalse(Files.exists(p));
         Files.delete(p);
 
@@ -168,7 +176,7 @@ public class FileTest {
 
     @Test
     public void givenInexistentFile_whenDeleteIfExistsWorks_thenCorrect() throws IOException {
-        Path p = Paths.get(HOME + "/inexistentFile.txt");
+        Path p = Paths.get(TEMP_DIR + "/inexistentFile.txt");
         assertFalse(Files.exists(p));
         Files.deleteIfExists(p);
 
@@ -177,8 +185,8 @@ public class FileTest {
     // copy file
     @Test
     public void givenFilePath_whenCopiesToNewLocation_thenCorrect() throws IOException {
-        Path dir1 = Paths.get(HOME + "/firstdir_" + UUID.randomUUID().toString());
-        Path dir2 = Paths.get(HOME + "/otherdir_" + UUID.randomUUID().toString());
+        Path dir1 = Paths.get(TEMP_DIR + "/firstdir_" + UUID.randomUUID().toString());
+        Path dir2 = Paths.get(TEMP_DIR + "/otherdir_" + UUID.randomUUID().toString());
         Files.createDirectory(dir1);
         Files.createDirectory(dir2);
         Path file1 = dir1.resolve("filetocopy.txt");
@@ -193,8 +201,8 @@ public class FileTest {
 
     @Test(expected = FileAlreadyExistsException.class)
     public void givenPath_whenCopyFailsDueToExistingFile_thenCorrect() throws IOException {
-        Path dir1 = Paths.get(HOME + "/firstdir_" + UUID.randomUUID().toString());
-        Path dir2 = Paths.get(HOME + "/otherdir_" + UUID.randomUUID().toString());
+        Path dir1 = Paths.get(TEMP_DIR + "/firstdir_" + UUID.randomUUID().toString());
+        Path dir2 = Paths.get(TEMP_DIR + "/otherdir_" + UUID.randomUUID().toString());
         Files.createDirectory(dir1);
         Files.createDirectory(dir2);
         Path file1 = dir1.resolve("filetocopy.txt");
@@ -210,8 +218,8 @@ public class FileTest {
     // moving files
     @Test
     public void givenFilePath_whenMovesToNewLocation_thenCorrect() throws IOException {
-        Path dir1 = Paths.get(HOME + "/firstdir_" + UUID.randomUUID().toString());
-        Path dir2 = Paths.get(HOME + "/otherdir_" + UUID.randomUUID().toString());
+        Path dir1 = Paths.get(TEMP_DIR + "/firstdir_" + UUID.randomUUID().toString());
+        Path dir2 = Paths.get(TEMP_DIR + "/otherdir_" + UUID.randomUUID().toString());
         Files.createDirectory(dir1);
         Files.createDirectory(dir2);
         Path file1 = dir1.resolve("filetocopy.txt");
@@ -227,8 +235,8 @@ public class FileTest {
 
     @Test(expected = FileAlreadyExistsException.class)
     public void givenFilePath_whenMoveFailsDueToExistingFile_thenCorrect() throws IOException {
-        Path dir1 = Paths.get(HOME + "/firstdir_" + UUID.randomUUID().toString());
-        Path dir2 = Paths.get(HOME + "/otherdir_" + UUID.randomUUID().toString());
+        Path dir1 = Paths.get(TEMP_DIR + "/firstdir_" + UUID.randomUUID().toString());
+        Path dir2 = Paths.get(TEMP_DIR + "/otherdir_" + UUID.randomUUID().toString());
         Files.createDirectory(dir1);
         Files.createDirectory(dir2);
         Path file1 = dir1.resolve("filetocopy.txt");

core-java/src/test/java/com/baeldung/java/nio2/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+- [Introduction to the Java NIO2 File API](http://www.baeldung.com/java-nio-2-file-api)
+- [Java NIO2 Path API](http://www.baeldung.com/java-nio-2-path)

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoClient.java

@@ -0,0 +1,86 @@
+package com.baeldung.java.nio2.async;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+public class AsyncEchoClient {
+    private AsynchronousSocketChannel client;
+    private Future<Void> future;
+    private static AsyncEchoClient instance;
+
+    private AsyncEchoClient() {
+        try {
+            client = AsynchronousSocketChannel.open();
+            InetSocketAddress hostAddress = new InetSocketAddress("localhost", 4999);
+            future = client.connect(hostAddress);
+            start();
+
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static AsyncEchoClient getInstance() {
+        if (instance == null)
+            instance = new AsyncEchoClient();
+        return instance;
+    }
+
+    private void start() {
+        try {
+            future.get();
+        } catch (InterruptedException | ExecutionException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public String sendMessage(String message) {
+        byte[] byteMsg = message.getBytes();
+        ByteBuffer buffer = ByteBuffer.wrap(byteMsg);
+        Future<Integer> writeResult = client.write(buffer);
+
+        try {
+            writeResult.get();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        buffer.flip();
+        Future<Integer> readResult = client.read(buffer);
+        try {
+            readResult.get();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        String echo = new String(buffer.array()).trim();
+        buffer.clear();
+        return echo;
+    }
+
+    public void stop() {
+        try {
+            client.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        AsyncEchoClient client = AsyncEchoClient.getInstance();
+        client.start();
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        String line;
+        System.out.println("Message to server:");
+        while ((line = br.readLine()) != null) {
+            String response = client.sendMessage(line);
+            System.out.println("response from server: " + response);
+            System.out.println("Message to server:");
+        }
+    }
+
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoServer.java

@@ -0,0 +1,80 @@
+package com.baeldung.java.nio2.async;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousServerSocketChannel;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+public class AsyncEchoServer {
+    private AsynchronousServerSocketChannel serverChannel;
+    private Future<AsynchronousSocketChannel> acceptResult;
+    private AsynchronousSocketChannel clientChannel;
+
+    public AsyncEchoServer() {
+        try {
+            serverChannel = AsynchronousServerSocketChannel.open();
+            InetSocketAddress hostAddress = new InetSocketAddress("localhost", 4999);
+            serverChannel.bind(hostAddress);
+            acceptResult = serverChannel.accept();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public void runServer() {
+        try {
+            clientChannel = acceptResult.get();
+            if ((clientChannel != null) && (clientChannel.isOpen())) {
+                while (true) {
+
+                    ByteBuffer buffer = ByteBuffer.allocate(32);
+                    Future<Integer> readResult = clientChannel.read(buffer);
+
+                    // do some computation
+
+                    readResult.get();
+
+                    buffer.flip();
+                    String message = new String(buffer.array()).trim();
+                    if (message.equals("bye")) {
+                        break; // while loop
+                    }
+                    buffer = ByteBuffer.wrap(new String(message).getBytes());
+                    Future<Integer> writeResult = clientChannel.write(buffer);
+
+                    // do some computation
+                    writeResult.get();
+                    buffer.clear();
+
+                } // while()
+
+                clientChannel.close();
+                serverChannel.close();
+
+            }
+        } catch (InterruptedException | ExecutionException | IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    public static void main(String[] args) {
+        AsyncEchoServer server = new AsyncEchoServer();
+        server.runServer();
+    }
+
+    public static Process start() throws IOException, InterruptedException {
+        String javaHome = System.getProperty("java.home");
+        String javaBin = javaHome + File.separator + "bin" + File.separator + "java";
+        String classpath = System.getProperty("java.class.path");
+        String className = AsyncEchoServer.class.getCanonicalName();
+
+        ProcessBuilder builder = new ProcessBuilder(javaBin, "-cp", classpath, className);
+
+        return builder.start();
+    }
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoServer2.java

@@ -0,0 +1,99 @@
+package com.baeldung.java.nio2.async;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousServerSocketChannel;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.nio.channels.CompletionHandler;
+import java.util.HashMap;
+import java.util.Map;
+
+public class AsyncEchoServer2 {
+    private AsynchronousServerSocketChannel serverChannel;
+    private AsynchronousSocketChannel clientChannel;
+
+    public AsyncEchoServer2() {
+        try {
+            serverChannel = AsynchronousServerSocketChannel.open();
+            InetSocketAddress hostAddress = new InetSocketAddress("localhost", 4999);
+            serverChannel.bind(hostAddress);
+            while (true) {
+
+                serverChannel.accept(null, new CompletionHandler<AsynchronousSocketChannel, Object>() {
+
+                    @Override
+                    public void completed(AsynchronousSocketChannel result, Object attachment) {
+                        if (serverChannel.isOpen())
+                            serverChannel.accept(null, this);
+                        clientChannel = result;
+                        if ((clientChannel != null) && (clientChannel.isOpen())) {
+                            ReadWriteHandler handler = new ReadWriteHandler();
+                            ByteBuffer buffer = ByteBuffer.allocate(32);
+                            Map<String, Object> readInfo = new HashMap<>();
+                            readInfo.put("action", "read");
+                            readInfo.put("buffer", buffer);
+                            clientChannel.read(buffer, readInfo, handler);
+                        }
+                    }
+
+                    @Override
+                    public void failed(Throwable exc, Object attachment) {
+                        // process error
+                    }
+                });
+                try {
+                    System.in.read();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    class ReadWriteHandler implements CompletionHandler<Integer, Map<String, Object>> {
+
+        @Override
+        public void completed(Integer result, Map<String, Object> attachment) {
+            Map<String, Object> actionInfo = attachment;
+            String action = (String) actionInfo.get("action");
+            if ("read".equals(action)) {
+                ByteBuffer buffer = (ByteBuffer) actionInfo.get("buffer");
+                buffer.flip();
+                actionInfo.put("action", "write");
+                clientChannel.write(buffer, actionInfo, this);
+                buffer.clear();
+            } else if ("write".equals(action)) {
+                ByteBuffer buffer = ByteBuffer.allocate(32);
+                actionInfo.put("action", "read");
+                actionInfo.put("buffer", buffer);
+                clientChannel.read(buffer, actionInfo, this);
+            }
+
+        }
+
+        @Override
+        public void failed(Throwable exc, Map<String, Object> attachment) {
+
+        }
+
+    }
+
+    public static void main(String[] args) {
+        new AsyncEchoServer2();
+    }
+
+    public static Process start() throws IOException, InterruptedException {
+        String javaHome = System.getProperty("java.home");
+        String javaBin = javaHome + File.separator + "bin" + File.separator + "java";
+        String classpath = System.getProperty("java.class.path");
+        String className = AsyncEchoServer2.class.getCanonicalName();
+
+        ProcessBuilder builder = new ProcessBuilder(javaBin, "-cp", classpath, className);
+
+        return builder.start();
+    }
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.java.nio2.async;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+
+public class AsyncEchoTest {
+
+    Process server;
+    AsyncEchoClient client;
+
+    @Before
+    public void setup() throws IOException, InterruptedException {
+        server = AsyncEchoServer2.start();
+        client = AsyncEchoClient.getInstance();
+    }
+
+    @Test
+    public void givenServerClient_whenServerEchosMessage_thenCorrect() throws Exception {
+        String resp1 = client.sendMessage("hello");
+        String resp2 = client.sendMessage("world");
+        assertEquals("hello", resp1);
+        assertEquals("world", resp2);
+    }
+
+    @After
+    public void teardown() throws IOException {
+        server.destroy();
+        client.stop();
+    }
+
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncFileTest.java

@@ -0,0 +1,126 @@
+package com.baeldung.java.nio2.async;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URI;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousFileChannel;
+import java.nio.channels.CompletionHandler;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.UUID;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+import static org.junit.Assert.assertEquals;
+
+public class AsyncFileTest {
+    @Test
+    public void givenPath_whenReadsContentWithFuture_thenCorrect() throws IOException, ExecutionException, InterruptedException {
+        Path path = Paths.get(URI.create(this.getClass().getClassLoader().getResource("file.txt").toString()));
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+
+        Future<Integer> operation = fileChannel.read(buffer, 0);
+
+        operation.get();
+
+        String fileContent = new String(buffer.array()).trim();
+        buffer.clear();
+
+        assertEquals(fileContent, "baeldung.com");
+    }
+
+    @Test
+    public void givenPath_whenReadsContentWithCompletionHandler_thenCorrect() throws IOException {
+        Path path = Paths.get(URI.create(AsyncFileTest.class.getResource("/file.txt").toString()));
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+
+        fileChannel.read(buffer, 0, buffer, new CompletionHandler<Integer, ByteBuffer>() {
+
+            @Override
+            public void completed(Integer result, ByteBuffer attachment) {
+                // result is number of bytes read
+                // attachment is the buffer
+
+            }
+
+            @Override
+            public void failed(Throwable exc, ByteBuffer attachment) {
+
+            }
+        });
+    }
+
+    @Test
+    public void givenPathAndContent_whenWritesToFileWithFuture_thenCorrect() throws IOException, ExecutionException, InterruptedException {
+        String fileName = "temp";
+        Path path = Paths.get(fileName);
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.WRITE, StandardOpenOption.CREATE);
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+        long position = 0;
+
+        buffer.put("hello world".getBytes());
+        buffer.flip();
+
+        Future<Integer> operation = fileChannel.write(buffer, position);
+        buffer.clear();
+
+        operation.get();
+
+        String content = readContent(path);
+        assertEquals("hello world", content);
+    }
+
+    @Test
+    public void givenPathAndContent_whenWritesToFileWithHandler_thenCorrect() throws IOException {
+        String fileName = UUID.randomUUID().toString();
+        Path path = Paths.get(fileName);
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.DELETE_ON_CLOSE);
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+        buffer.put("hello world".getBytes());
+        buffer.flip();
+
+        fileChannel.write(buffer, 0, buffer, new CompletionHandler<Integer, ByteBuffer>() {
+
+            @Override
+            public void completed(Integer result, ByteBuffer attachment) {
+                // result is number of bytes written
+                // attachment is the buffer
+
+            }
+
+            @Override
+            public void failed(Throwable exc, ByteBuffer attachment) {
+
+            }
+        });
+    }
+
+    public static String readContent(Path file) throws ExecutionException, InterruptedException {
+        AsynchronousFileChannel fileChannel = null;
+        try {
+            fileChannel = AsynchronousFileChannel.open(file, StandardOpenOption.READ);
+        } catch (IOException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        }
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+
+        Future<Integer> operation = fileChannel.read(buffer, 0);
+
+        operation.get();
+
+        String fileContent = new String(buffer.array()).trim();
+        buffer.clear();
+        return fileContent;
+    }
+}

core-java/src/test/java/com/baeldung/java/nio2/attributes/BasicAttribsTest.java

@@ -0,0 +1,69 @@
+package com.baeldung.java.nio2.attributes;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.BasicFileAttributeView;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.nio.file.attribute.FileTime;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class BasicAttribsTest {
+    private static final String HOME = System.getProperty("user.home");
+    private static BasicFileAttributes basicAttribs;
+
+    @BeforeClass
+    public static void setup() throws IOException {
+        Path home = Paths.get(HOME);
+        BasicFileAttributeView basicView = Files.getFileAttributeView(home, BasicFileAttributeView.class);
+        basicAttribs = basicView.readAttributes();
+    }
+
+    @Test
+    public void givenFileTimes_whenComparesThem_ThenCorrect() {
+        FileTime created = basicAttribs.creationTime();
+        FileTime modified = basicAttribs.lastModifiedTime();
+        FileTime accessed = basicAttribs.lastAccessTime();
+
+        System.out.println("Created: " + created);
+        System.out.println("Modified: " + modified);
+        System.out.println("Accessed: " + accessed);
+
+    }
+
+    @Test
+    public void givenPath_whenGetsFileSize_thenCorrect() {
+        long size = basicAttribs.size();
+        assertTrue(size > 0);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfDirectory_thenCorrect() {
+        boolean isDir = basicAttribs.isDirectory();
+        assertTrue(isDir);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfFile_thenCorrect() {
+        boolean isFile = basicAttribs.isRegularFile();
+        assertFalse(isFile);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfSymLink_thenCorrect() {
+        boolean isSymLink = basicAttribs.isSymbolicLink();
+        assertFalse(isSymLink);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfOther_thenCorrect() {
+        boolean isOther = basicAttribs.isOther();
+        assertFalse(isOther);
+    }
+}

core-java/src/test/java/com/baeldung/java8/Java8CollectionCleanupUnitTest.java

@@ -4,6 +4,7 @@ import com.google.common.collect.Lists;
 import org.junit.Test;
 
 import java.util.List;
+import java.util.Objects;
 import java.util.stream.Collectors;
 
 import static org.hamcrest.Matchers.hasSize;
@@ -16,7 +17,7 @@ public class Java8CollectionCleanupUnitTest {
     @Test
     public void givenListContainsNulls_whenFilteringParallel_thenCorrect() {
         final List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
-        final List<Integer> listWithoutNulls = list.parallelStream().filter(i -> i != null).collect(Collectors.toList());
+        final List<Integer> listWithoutNulls = list.parallelStream().filter(Objects::nonNull).collect(Collectors.toList());
 
         assertThat(listWithoutNulls, hasSize(3));
     }
@@ -24,7 +25,7 @@ public class Java8CollectionCleanupUnitTest {
     @Test
     public void givenListContainsNulls_whenFilteringSerial_thenCorrect() {
         final List<Integer> list = Lists.newArrayList(null, 1, 2, null, 3, null);
-        final List<Integer> listWithoutNulls = list.stream().filter(i -> i != null).collect(Collectors.toList());
+        final List<Integer> listWithoutNulls = list.stream().filter(Objects::nonNull).collect(Collectors.toList());
 
         assertThat(listWithoutNulls, hasSize(3));
     }
@@ -32,7 +33,7 @@ public class Java8CollectionCleanupUnitTest {
     @Test
     public void givenListContainsNulls_whenRemovingNullsWithRemoveIf_thenCorrect() {
         final List<Integer> listWithoutNulls = Lists.newArrayList(null, 1, 2, null, 3, null);
-        listWithoutNulls.removeIf(p -> p == null);
+        listWithoutNulls.removeIf(Objects::isNull);
 
         assertThat(listWithoutNulls, hasSize(3));
     }

core-java/src/test/java/com/baeldung/java8/JavaFileSizeUnitTest.java

@@ -0,0 +1,65 @@
+package com.baeldung.java8;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import org.apache.commons.io.FileUtils;
+import org.junit.Before;
+import org.junit.Test;
+
+public class JavaFileSizeUnitTest {
+    private static final long EXPECTED_FILE_SIZE_IN_BYTES = 11;
+    private String filePath;
+
+    @Before
+    public void init() {
+        final String separator = File.separator;
+        filePath = String.join(separator, new String[] { "src", "test", "resources", "testFolder", "sample_file_1.in" });
+    }
+
+    @Test
+    public void whenGetFileSize_thenCorrect() {
+        final File file = new File(filePath);
+
+        final long size = getFileSize(file);
+
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES, size);
+    }
+
+    @Test
+    public void whenGetFileSizeUsingNioApi_thenCorrect() throws IOException {
+        final Path path = Paths.get(this.filePath);
+        final FileChannel fileChannel = FileChannel.open(path);
+
+        final long fileSize = fileChannel.size();
+
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES, fileSize);
+    }
+
+    @Test
+    public void whenGetFileSizeUsingApacheCommonsIO_thenCorrect() {
+        final File file = new File(filePath);
+
+        final long size = FileUtils.sizeOf(file);
+
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES, size);
+    }
+
+    @Test
+    public void whenGetReadableFileSize_thenCorrect() {
+        final File file = new File(filePath);
+
+        final long size = getFileSize(file);
+
+        assertEquals(EXPECTED_FILE_SIZE_IN_BYTES + " bytes", FileUtils.byteCountToDisplaySize(size));
+    }
+
+    private long getFileSize(final File file) {
+        final long length = file.length();
+        return length;
+    }
+}

core-java/src/test/java/com/baeldung/java8/JavaTryWithResourcesLongRunningUnitTest.java

@@ -8,7 +8,7 @@ import java.io.StringWriter;
 import java.util.Date;
 import java.util.Scanner;
 
-public class JavaTryWithResourcesUnitTest {
+public class JavaTryWithResourcesLongRunningUnitTest {
 
     private static final String TEST_STRING_HELLO_WORLD = "Hello World";
     private Date resource1Date, resource2Date;

core-java/src/test/java/com/baeldung/java8/optional/OptionalTest.java

@@ -0,0 +1,235 @@
+package com.baeldung.java8.optional;
+
+import com.baeldung.optional.Modem;
+import com.baeldung.optional.Person;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Optional;
+
+import static org.junit.Assert.*;
+
+public class OptionalTest {
+    // creating Optional
+    @Test
+    public void whenCreatesEmptyOptional_thenCorrect() {
+        Optional<String> empty = Optional.empty();
+        assertFalse(empty.isPresent());
+    }
+
+    @Test
+    public void givenNonNull_whenCreatesNonNullable_thenCorrect() {
+        String name = "baeldung";
+        Optional.of(name);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void givenNull_whenThrowsErrorOnCreate_thenCorrect() {
+        String name = null;
+        Optional<String> opt = Optional.of(name);
+    }
+
+    @Test
+    public void givenNonNull_whenCreatesOptional_thenCorrect() {
+        String name = "baeldung";
+        Optional<String> opt = Optional.of(name);
+        assertEquals("Optional[baeldung]", opt.toString());
+    }
+
+    @Test
+    public void givenNonNull_whenCreatesNullable_thenCorrect() {
+        String name = "baeldung";
+        Optional<String> opt = Optional.ofNullable(name);
+        assertEquals("Optional[baeldung]", opt.toString());
+    }
+
+    @Test
+    public void givenNull_whenCreatesNullable_thenCorrect() {
+        String name = null;
+        Optional<String> opt = Optional.ofNullable(name);
+        assertEquals("Optional.empty", opt.toString());
+    }
+    // Checking Value With isPresent()
+
+    @Test
+    public void givenOptional_whenIsPresentWorks_thenCorrect() {
+        Optional<String> opt = Optional.of("Baeldung");
+        assertTrue(opt.isPresent());
+
+        opt = Optional.ofNullable(null);
+        assertFalse(opt.isPresent());
+    }
+
+    // Condition Action With ifPresent()
+    @Test
+    public void givenOptional_whenIfPresentWorks_thenCorrect() {
+        Optional<String> opt = Optional.of("baeldung");
+        opt.ifPresent(name -> System.out.println(name.length()));
+    }
+
+    // returning Value With get()
+    @Test
+    public void givenOptional_whenGetsValue_thenCorrect() {
+        Optional<String> opt = Optional.of("baeldung");
+        String name = opt.get();
+        assertEquals("baeldung", name);
+    }
+
+    @Test(expected = NoSuchElementException.class)
+    public void givenOptionalWithNull_whenGetThrowsException_thenCorrect() {
+        Optional<String> opt = Optional.ofNullable(null);
+        String name = opt.get();
+    }
+
+    // Conditional Return With filter()
+    @Test
+    public void whenOptionalFilterWorks_thenCorrect() {
+        Integer year = 2016;
+        Optional<Integer> yearOptional = Optional.of(year);
+        boolean is2016 = yearOptional.filter(y -> y == 2016).isPresent();
+        assertTrue(is2016);
+        boolean is2017 = yearOptional.filter(y -> y == 2017).isPresent();
+        assertFalse(is2017);
+    }
+
+    @Test
+    public void whenFiltersWithoutOptional_thenCorrect() {
+        assertTrue(priceIsInRange1(new Modem(10.0)));
+        assertFalse(priceIsInRange1(new Modem(9.9)));
+        assertFalse(priceIsInRange1(new Modem(null)));
+        assertFalse(priceIsInRange1(new Modem(15.5)));
+        assertFalse(priceIsInRange1(null));
+
+    }
+
+    @Test
+    public void whenFiltersWithOptional_thenCorrect() {
+        assertTrue(priceIsInRange2(new Modem(10.0)));
+        assertFalse(priceIsInRange2(new Modem(9.9)));
+        assertFalse(priceIsInRange2(new Modem(null)));
+        assertFalse(priceIsInRange2(new Modem(15.5)));
+        assertFalse(priceIsInRange1(null));
+    }
+
+    public boolean priceIsInRange1(Modem modem) {
+        boolean isInRange = false;
+        if (modem != null && modem.getPrice() != null && (modem.getPrice() >= 10 && modem.getPrice() <= 15)) {
+            isInRange = true;
+        }
+        return isInRange;
+    }
+
+    public boolean priceIsInRange2(Modem modem2) {
+        return Optional.ofNullable(modem2).map(Modem::getPrice).filter(p -> p >= 10).filter(p -> p <= 15).isPresent();
+    }
+
+    // Transforming Value With map()
+    @Test
+    public void givenOptional_whenMapWorks_thenCorrect() {
+        List<String> companyNames = Arrays.asList("paypal", "oracle", "", "microsoft", "", "apple");
+        Optional<List<String>> listOptional = Optional.of(companyNames);
+
+        int size = listOptional.map(List::size).orElse(0);
+        assertEquals(6, size);
+    }
+
+    @Test
+    public void givenOptional_whenMapWorks_thenCorrect2() {
+        String name = "baeldung";
+        Optional<String> nameOptional = Optional.of(name);
+
+        int len = nameOptional.map(String::length).orElse(0);
+        assertEquals(8, len);
+    }
+
+    @Test
+    public void givenOptional_whenMapWorksWithFilter_thenCorrect() {
+        String password = " password ";
+        Optional<String> passOpt = Optional.of(password);
+        boolean correctPassword = passOpt.filter(pass -> pass.equals("password")).isPresent();
+        assertFalse(correctPassword);
+
+        correctPassword = passOpt.map(String::trim).filter(pass -> pass.equals("password")).isPresent();
+        assertTrue(correctPassword);
+    }
+
+    // Transforming Value With flatMap()
+    @Test
+    public void givenOptional_whenFlatMapWorks_thenCorrect2() {
+        Person person = new Person("john", 26);
+        Optional<Person> personOptional = Optional.of(person);
+
+        Optional<Optional<String>> nameOptionalWrapper = personOptional.map(Person::getName);
+        Optional<String> nameOptional = nameOptionalWrapper.orElseThrow(IllegalArgumentException::new);
+        String name1 = nameOptional.orElseThrow(IllegalArgumentException::new);
+        assertEquals("john", name1);
+
+        String name = personOptional.flatMap(Person::getName).orElseThrow(IllegalArgumentException::new);
+        assertEquals("john", name);
+    }
+
+    @Test
+    public void givenOptional_whenFlatMapWorksWithFilter_thenCorrect() {
+        Person person = new Person("john", 26);
+        person.setPassword("password");
+        Optional<Person> personOptional = Optional.of(person);
+
+        String password = personOptional.flatMap(Person::getPassword).filter(cleanPass -> cleanPass.equals("password")).orElseThrow(IllegalArgumentException::new);
+        assertEquals("password", password);
+    }
+
+    // Default Value With orElse
+    @Test
+    public void whenOrElseWorks_thenCorrect() {
+        String nullName = null;
+        String name = Optional.ofNullable(nullName).orElse("john");
+        assertEquals("john", name);
+    }
+
+    // Default Value With orElseGet
+    @Test
+    public void whenOrElseGetWorks_thenCorrect() {
+        String nullName = null;
+        String name = Optional.ofNullable(nullName).orElseGet(() -> "john");
+        assertEquals("john", name);
+
+    }
+
+    @Test
+    public void whenOrElseGetAndOrElseOverlap_thenCorrect() {
+        String text = null;
+        System.out.println("Using orElseGet:");
+        String defaultText = Optional.ofNullable(text).orElseGet(this::getMyDefault);
+        assertEquals("Default Value", defaultText);
+
+        System.out.println("Using orElse:");
+        defaultText = Optional.ofNullable(text).orElse(getMyDefault());
+        assertEquals("Default Value", defaultText);
+    }
+
+    @Test
+    public void whenOrElseGetAndOrElseDiffer_thenCorrect() {
+        String text = "Text present";
+        System.out.println("Using orElseGet:");
+        String defaultText = Optional.ofNullable(text).orElseGet(this::getMyDefault);
+        assertEquals("Text present", defaultText);
+
+        System.out.println("Using orElse:");
+        defaultText = Optional.ofNullable(text).orElse(getMyDefault());
+        assertEquals("Text present", defaultText);
+    }
+
+    // Exceptions With orElseThrow
+    @Test(expected = IllegalArgumentException.class)
+    public void whenOrElseThrowWorks_thenCorrect() {
+        String nullName = null;
+        String name = Optional.ofNullable(nullName).orElseThrow(IllegalArgumentException::new);
+    }
+
+    public String getMyDefault() {
+        System.out.println("Getting default value...");
+        return "Default Value";
+    }
+}

core-java/src/test/java/org/baeldung/java/collections/CollectionsConcatenateUnitTest.java

@@ -0,0 +1,135 @@
+package org.baeldung.java.collections;
+
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Lists;
+
+import org.apache.commons.collections4.CollectionUtils;
+import org.apache.commons.collections4.IterableUtils;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static java.util.Arrays.asList;
+
+public class CollectionsConcatenateUnitTest {
+
+    @Test
+    public void givenUsingJava8_whenConcatenatingUsingConcat_thenCorrect() {
+        Collection<String> collectionA = asList("S", "T");
+        Collection<String> collectionB = asList("U", "V");
+        Collection<String> collectionC = asList("W", "X");
+
+        Stream<String> combinedStream = Stream.concat(Stream.concat(collectionA.stream(), collectionB.stream()), collectionC.stream());
+        Collection<String> collectionCombined = combinedStream.collect(Collectors.toList());
+
+        Assert.assertEquals(asList("S", "T", "U", "V", "W", "X"), collectionCombined);
+    }
+
+    @Test
+    public void givenUsingJava8_whenConcatenatingUsingflatMap_thenCorrect() {
+        Collection<String> collectionA = asList("S", "T");
+        Collection<String> collectionB = asList("U", "V");
+
+        Stream<String> combinedStream = Stream.of(collectionA, collectionB).flatMap(Collection::stream);
+        Collection<String> collectionCombined = combinedStream.collect(Collectors.toList());
+
+        Assert.assertEquals(asList("S", "T", "U", "V"), collectionCombined);
+    }
+
+    @Test
+    public void givenUsingGuava_whenConcatenatingUsingIterables_thenCorrect() {
+        Collection<String> collectionA = asList("S", "T");
+        Collection<String> collectionB = asList("U", "V");
+
+        Iterable<String> combinedIterables = Iterables.unmodifiableIterable(Iterables.concat(collectionA, collectionB));
+        Collection<String> collectionCombined = Lists.newArrayList(combinedIterables);
+
+        Assert.assertEquals(asList("S", "T", "U", "V"), collectionCombined);
+    }
+
+    @Test
+    public void givenUsingJava7_whenConcatenatingUsingIterables_thenCorrect() {
+        Collection<String> collectionA = asList("S", "T");
+        Collection<String> collectionB = asList("U", "V");
+
+        Iterable<String> combinedIterables = concat(collectionA, collectionB);
+        Collection<String> collectionCombined = makeListFromIterable(combinedIterables);
+        Assert.assertEquals(Arrays.asList("S", "T", "U", "V"), collectionCombined);
+    }
+
+    public static <E> Iterable<E> concat(Iterable<? extends E> i1, Iterable<? extends E> i2) {
+        return new Iterable<E>() {
+            public Iterator<E> iterator() {
+                return new Iterator<E>() {
+                    Iterator<? extends E> listIterator = i1.iterator();
+                    Boolean checkedHasNext;
+                    E nextValue;
+                    private boolean startTheSecond;
+
+                    void theNext() {
+                        if (listIterator.hasNext()) {
+                            checkedHasNext = true;
+                            nextValue = listIterator.next();
+                        } else if (startTheSecond)
+                            checkedHasNext = false;
+                        else {
+                            startTheSecond = true;
+                            listIterator = i2.iterator();
+                            theNext();
+                        }
+                    }
+
+                    public boolean hasNext() {
+                        if (checkedHasNext == null)
+                            theNext();
+                        return checkedHasNext;
+                    }
+
+                    public E next() {
+                        if (!hasNext())
+                            throw new NoSuchElementException();
+                        checkedHasNext = null;
+                        return nextValue;
+                    }
+
+                    public void remove() {
+                        listIterator.remove();
+                    }
+                };
+            }
+        };
+    }
+
+    public static <E> List<E> makeListFromIterable(Iterable<E> iter) {
+        List<E> list = new ArrayList<>();
+        for (E item : iter) {
+            list.add(item);
+        }
+        return list;
+    }
+
+    @Test
+    public void givenUsingApacheCommons_whenConcatenatingUsingUnion_thenCorrect() {
+        Collection<String> collectionA = asList("S", "T");
+        Collection<String> collectionB = asList("U", "V");
+
+        Iterable<String> combinedIterables = CollectionUtils.union(collectionA, collectionB);
+        Collection<String> collectionCombined = Lists.newArrayList(combinedIterables);
+
+        Assert.assertEquals(asList("S", "T", "U", "V"), collectionCombined);
+    }
+
+    @Test
+    public void givenUsingApacheCommons_whenConcatenatingUsingChainedIterable_thenCorrect() {
+        Collection<String> collectionA = asList("S", "T");
+        Collection<String> collectionB = asList("U", "V");
+
+        Iterable<String> combinedIterables = IterableUtils.chainedIterable(collectionA, collectionB);
+        Collection<String> collectionCombined = Lists.newArrayList(combinedIterables);
+
+        Assert.assertEquals(asList("S", "T", "U", "V"), collectionCombined);
+    }
+}

core-java/src/test/java/org/baeldung/java/collections/JoinSplitCollectionsUnitTest.java

@@ -0,0 +1,154 @@
+package org.baeldung.java.collections;
+
+import org.junit.Test;
+
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.*;
+
+public class JoinSplitCollectionsUnitTest {
+
+    @Test
+    public void whenJoiningTwoArrays_thenJoined() {
+        String[] animals1 = new String[] { "Dog", "Cat" };
+        String[] animals2 = new String[] { "Bird", "Cow" };
+        String[] result = Stream.concat(Arrays.stream(animals1), Arrays.stream(animals2)).toArray(String[]::new);
+
+        assertArrayEquals(result, new String[] { "Dog", "Cat", "Bird", "Cow" });
+    }
+
+    @Test
+    public void whenJoiningTwoCollections_thenJoined() {
+        Collection<String> collection1 = Arrays.asList("Dog", "Cat");
+        Collection<String> collection2 = Arrays.asList("Bird", "Cow", "Moose");
+        Collection<String> result = Stream.concat(collection1.stream(), collection2.stream()).collect(Collectors.toList());
+
+        assertTrue(result.equals(Arrays.asList("Dog", "Cat", "Bird", "Cow", "Moose")));
+    }
+
+    @Test
+    public void whenJoiningTwoCollectionsWithFilter_thenJoined() {
+        Collection<String> collection1 = Arrays.asList("Dog", "Cat");
+        Collection<String> collection2 = Arrays.asList("Bird", "Cow", "Moose");
+        Collection<String> result = Stream.concat(collection1.stream(), collection2.stream()).filter(e -> e.length() == 3).collect(Collectors.toList());
+
+        assertTrue(result.equals(Arrays.asList("Dog", "Cat", "Cow")));
+    }
+
+    @Test
+    public void whenConvertArrayToString_thenConverted() {
+        String[] animals = new String[] { "Dog", "Cat", "Bird", "Cow" };
+        String result = Arrays.stream(animals).collect(Collectors.joining(", "));
+
+        assertEquals(result, "Dog, Cat, Bird, Cow");
+    }
+
+    @Test
+    public void whenConvertCollectionToString_thenConverted() {
+        Collection<String> animals = Arrays.asList("Dog", "Cat", "Bird", "Cow");
+        String result = animals.stream().collect(Collectors.joining(", "));
+
+        assertEquals(result, "Dog, Cat, Bird, Cow");
+    }
+
+    @Test
+    public void whenConvertMapToString_thenConverted() {
+        Map<Integer, String> animals = new HashMap<>();
+        animals.put(1, "Dog");
+        animals.put(2, "Cat");
+        animals.put(3, "Cow");
+
+        String result = animals.entrySet().stream().map(entry -> entry.getKey() + " = " + entry.getValue()).collect(Collectors.joining(", "));
+
+        assertEquals(result, "1 = Dog, 2 = Cat, 3 = Cow");
+    }
+
+    @Test
+    public void whenConvertNestedCollectionToString_thenConverted() {
+        Collection<List<String>> nested = new ArrayList<>();
+        nested.add(Arrays.asList("Dog", "Cat"));
+        nested.add(Arrays.asList("Cow", "Pig"));
+
+        String result = nested.stream().map(nextList -> nextList.stream().collect(Collectors.joining("-"))).collect(Collectors.joining("; "));
+
+        assertEquals(result, "Dog-Cat; Cow-Pig");
+    }
+
+    @Test
+    public void whenConvertCollectionToStringAndSkipNull_thenConverted() {
+        Collection<String> animals = Arrays.asList("Dog", "Cat", null, "Moose");
+        String result = animals.stream().filter(Objects::nonNull).collect(Collectors.joining(", "));
+
+        assertEquals(result, "Dog, Cat, Moose");
+    }
+
+    @Test
+    public void whenSplitCollectionHalf_thenConverted() {
+        Collection<String> animals = Arrays.asList("Dog", "Cat", "Cow", "Bird", "Moose", "Pig");
+        Collection<String> result1 = new ArrayList<>();
+        Collection<String> result2 = new ArrayList<>();
+        AtomicInteger count = new AtomicInteger();
+        int midpoint = Math.round(animals.size() / 2);
+
+        animals.forEach(next -> {
+            int index = count.getAndIncrement();
+            if (index < midpoint) {
+                result1.add(next);
+            } else {
+                result2.add(next);
+            }
+        });
+
+        assertTrue(result1.equals(Arrays.asList("Dog", "Cat", "Cow")));
+        assertTrue(result2.equals(Arrays.asList("Bird", "Moose", "Pig")));
+    }
+
+    @Test
+    public void whenSplitArrayByWordLength_thenConverted() {
+        String[] animals = new String[] { "Dog", "Cat", "Bird", "Cow", "Pig", "Moose" };
+        Map<Integer, List<String>> result = Arrays.stream(animals).collect(Collectors.groupingBy(String::length));
+
+        assertTrue(result.get(3).equals(Arrays.asList("Dog", "Cat", "Cow", "Pig")));
+        assertTrue(result.get(4).equals(Arrays.asList("Bird")));
+        assertTrue(result.get(5).equals(Arrays.asList("Moose")));
+    }
+
+    @Test
+    public void whenConvertStringToArray_thenConverted() {
+        String animals = "Dog, Cat, Bird, Cow";
+        String[] result = animals.split(", ");
+
+        assertArrayEquals(result, new String[] { "Dog", "Cat", "Bird", "Cow" });
+    }
+
+    @Test
+    public void whenConvertStringToCollection_thenConverted() {
+        String animals = "Dog, Cat, Bird, Cow";
+        Collection<String> result = Arrays.asList(animals.split(", "));
+
+        assertTrue(result.equals(Arrays.asList("Dog", "Cat", "Bird", "Cow")));
+    }
+
+    @Test
+    public void whenConvertStringToMap_thenConverted() {
+        String animals = "1 = Dog, 2 = Cat, 3 = Bird";
+
+        Map<Integer, String> result = Arrays.stream(animals.split(", ")).map(next -> next.split(" = ")).collect(Collectors.toMap(entry -> Integer.parseInt(entry[0]), entry -> entry[1]));
+
+        assertEquals(result.get(1), "Dog");
+        assertEquals(result.get(2), "Cat");
+        assertEquals(result.get(3), "Bird");
+    }
+
+    @Test
+    public void whenConvertCollectionToStringMultipleSeparators_thenConverted() {
+        String animals = "Dog. , Cat, Bird. Cow";
+
+        Collection<String> result = Arrays.stream(animals.split("[,|.]")).map(String::trim).filter(next -> !next.isEmpty()).collect(Collectors.toList());
+
+        assertTrue(result.equals(Arrays.asList("Dog", "Cat", "Bird", "Cow")));
+    }
+}

core-java/src/test/java/org/baeldung/java/io/JavaFileUnitTest.java

@@ -1,7 +1,9 @@
 package org.baeldung.java.io;
 
-import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
-import static org.junit.Assert.assertTrue;
+import org.apache.commons.io.FileUtils;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
 
 import java.io.File;
 import java.io.IOException;
@@ -9,17 +11,28 @@ import java.nio.file.FileSystemException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.UUID;
 
-import org.apache.commons.io.FileUtils;
-import org.junit.Test;
+import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
+import static org.junit.Assert.assertTrue;
 
 public class JavaFileUnitTest {
 
-    // create a file
+    private static final String TEMP_DIR = "src/test/resources/temp" + UUID.randomUUID().toString();
+
+    @BeforeClass
+    public static void setup() throws IOException {
+        Files.createDirectory(Paths.get(TEMP_DIR));
+    }
+
+    @AfterClass
+    public static void cleanup() throws IOException {
+        FileUtils.deleteDirectory(new File(TEMP_DIR));
+    }
 
     @Test
     public final void givenUsingJDK6_whenCreatingFile_thenCorrect() throws IOException {
-        final File newFile = new File("src/test/resources/newFile_jdk6.txt");
+        final File newFile = new File(TEMP_DIR + "/newFile_jdk6.txt");
         final boolean success = newFile.createNewFile();
 
         assertTrue(success);
@@ -27,48 +40,48 @@ public class JavaFileUnitTest {
 
     @Test
     public final void givenUsingJDK7nio2_whenCreatingFile_thenCorrect() throws IOException {
-        final Path newFilePath = Paths.get("src/test/resources/newFile_jdk7.txt");
+        final Path newFilePath = Paths.get(TEMP_DIR + "/newFile_jdk7.txt");
         Files.createFile(newFilePath);
     }
 
     @Test
     public final void givenUsingCommonsIo_whenCreatingFile_thenCorrect() throws IOException {
-        FileUtils.touch(new File("src/test/resources/newFile_commonsio.txt"));
+        FileUtils.touch(new File(TEMP_DIR + "/newFile_commonsio.txt"));
     }
 
     @Test
     public final void givenUsingGuava_whenCreatingFile_thenCorrect() throws IOException {
-        com.google.common.io.Files.touch(new File("src/test/resources/newFile_guava.txt"));
+        com.google.common.io.Files.touch(new File(TEMP_DIR + "/newFile_guava.txt"));
     }
 
     // move a file
 
     @Test
     public final void givenUsingJDK6_whenMovingFile_thenCorrect() throws IOException {
-        final File fileToMove = new File("src/test/resources/toMoveFile_jdk6.txt");
+        final File fileToMove = new File(TEMP_DIR + "/toMoveFile_jdk6.txt");
         fileToMove.createNewFile();// .exists();
-        final File destDir = new File("src/test/resources/");
+        final File destDir = new File(TEMP_DIR + "/");
         destDir.mkdir();
 
-        final boolean isMoved = fileToMove.renameTo(new File("src/test/resources/movedFile_jdk6.txt"));
+        final boolean isMoved = fileToMove.renameTo(new File(TEMP_DIR + "/movedFile_jdk6.txt"));
         if (!isMoved) {
-            throw new FileSystemException("src/test/resources/movedFile_jdk6.txt");
+            throw new FileSystemException(TEMP_DIR + "/movedFile_jdk6.txt");
         }
     }
 
     @Test
     public final void givenUsingJDK7Nio2_whenMovingFile_thenCorrect() throws IOException {
-        final Path fileToMovePath = Files.createFile(Paths.get("src/test/resources/" + randomAlphabetic(5) + ".txt"));
-        final Path targetPath = Paths.get("src/main/resources/");
+        final Path fileToMovePath = Files.createFile(Paths.get(TEMP_DIR + "/" + randomAlphabetic(5) + ".txt"));
+        final Path targetPath = Paths.get(TEMP_DIR + "/");
 
         Files.move(fileToMovePath, targetPath.resolve(fileToMovePath.getFileName()));
     }
 
     @Test
     public final void givenUsingGuava_whenMovingFile_thenCorrect() throws IOException {
-        final File fileToMove = new File("src/test/resources/fileToMove.txt");
+        final File fileToMove = new File(TEMP_DIR + "/fileToMove.txt");
         fileToMove.createNewFile();
-        final File destDir = new File("src/main/resources/");
+        final File destDir = new File(TEMP_DIR + "/temp");
         final File targetFile = new File(destDir, fileToMove.getName());
         com.google.common.io.Files.createParentDirs(targetFile);
         com.google.common.io.Files.move(fileToMove, targetFile);
@@ -76,23 +89,24 @@ public class JavaFileUnitTest {
 
     @Test
     public final void givenUsingApache_whenMovingFile_thenCorrect() throws IOException {
-        FileUtils.touch(new File("src/test/resources/fileToMove_apache.txt"));
-        FileUtils.moveFile(FileUtils.getFile("src/test/resources/fileToMove_apache.txt"), FileUtils.getFile("src/test/resources/fileMoved_apache2.txt"));
+        FileUtils.touch(new File(TEMP_DIR + "/fileToMove_apache.txt"));
+        FileUtils.moveFile(FileUtils.getFile(TEMP_DIR + "/fileToMove_apache.txt"), FileUtils.getFile(TEMP_DIR + "/fileMoved_apache2.txt"));
     }
 
     @Test
     public final void givenUsingApache_whenMovingFileApproach2_thenCorrect() throws IOException {
-        FileUtils.touch(new File("src/test/resources/fileToMove_apache.txt"));
-        FileUtils.moveFileToDirectory(FileUtils.getFile("src/test/resources/fileToMove_apache.txt"), FileUtils.getFile("src/main/resources/"), true);
+        FileUtils.touch(new File(TEMP_DIR + "/fileToMove_apache.txt"));
+        Files.createDirectory(Paths.get(TEMP_DIR + "/temp"));
+        FileUtils.moveFileToDirectory(FileUtils.getFile(TEMP_DIR + "/fileToMove_apache.txt"), FileUtils.getFile(TEMP_DIR + "/temp"), true);
     }
 
     // delete a file
 
     @Test
     public final void givenUsingJDK6_whenDeletingAFile_thenCorrect() throws IOException {
-        new File("src/test/resources/fileToDelete_jdk6.txt").createNewFile();
+        new File(TEMP_DIR + "/fileToDelete_jdk6.txt").createNewFile();
 
-        final File fileToDelete = new File("src/test/resources/fileToDelete_jdk6.txt");
+        final File fileToDelete = new File(TEMP_DIR + "/fileToDelete_jdk6.txt");
         final boolean success = fileToDelete.delete();
 
         assertTrue(success);
@@ -100,17 +114,17 @@ public class JavaFileUnitTest {
 
     @Test
     public final void givenUsingJDK7nio2_whenDeletingAFile_thenCorrect() throws IOException {
-        Files.createFile(Paths.get("src/test/resources/fileToDelete_jdk7.txt"));
+        Files.createFile(Paths.get(TEMP_DIR + "/fileToDelete_jdk7.txt"));
 
-        final Path fileToDeletePath = Paths.get("src/test/resources/fileToDelete_jdk7.txt");
+        final Path fileToDeletePath = Paths.get(TEMP_DIR + "/fileToDelete_jdk7.txt");
         Files.delete(fileToDeletePath);
     }
 
     @Test
     public final void givenUsingCommonsIo_whenDeletingAFileV1_thenCorrect() throws IOException {
-        FileUtils.touch(new File("src/test/resources/fileToDelete_commonsIo.txt"));
+        FileUtils.touch(new File(TEMP_DIR + "/fileToDelete_commonsIo.txt"));
 
-        final File fileToDelete = FileUtils.getFile("src/test/resources/fileToDelete_commonsIo.txt");
+        final File fileToDelete = FileUtils.getFile(TEMP_DIR + "/fileToDelete_commonsIo.txt");
         final boolean success = FileUtils.deleteQuietly(fileToDelete);
 
         assertTrue(success);
@@ -118,9 +132,9 @@ public class JavaFileUnitTest {
 
     @Test
     public void givenUsingCommonsIo_whenDeletingAFileV2_thenCorrect() throws IOException {
-        FileUtils.touch(new File("src/test/resources/fileToDelete.txt"));
+        FileUtils.touch(new File(TEMP_DIR + "/fileToDelete.txt"));
 
-        FileUtils.forceDelete(FileUtils.getFile("src/test/resources/fileToDelete.txt"));
+        FileUtils.forceDelete(FileUtils.getFile(TEMP_DIR + "/fileToDelete.txt"));
     }
 
 }

core-java/src/test/java/org/baeldung/java/sorting/Employee.java

@@ -0,0 +1,55 @@
+package org.baeldung.java.sorting;
+
+public class Employee implements Comparable {
+
+    private String name;
+    private int age;
+    private double salary;
+
+    public Employee(String name, int age, double salary) {
+        this.name = name;
+        this.age = age;
+        this.salary = salary;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public double getSalary() {
+        return salary;
+    }
+
+    public void setSalary(double salary) {
+        this.salary = salary;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return ((Employee) obj).getName().equals(getName());
+    }
+
+    @Override
+    public int compareTo(Object o) {
+        Employee e = (Employee) o;
+        return getName().compareTo(e.getName());
+    }
+
+    @Override
+    public String toString() {
+        return new StringBuffer().append("(").append(getName()).append(getAge()).append(",").append(getSalary()).append(")").toString();
+    }
+
+}

core-java/src/test/java/org/baeldung/java/sorting/JavaSorting.java

@@ -0,0 +1,186 @@
+package org.baeldung.java.sorting;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.commons.lang3.ArrayUtils;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.google.common.primitives.Ints;
+
+public class JavaSorting {
+
+    private int[] toSort;
+    private int[] sortedInts;
+    private int[] sortedRangeInts;
+    // private Integer [] integers;
+    // private Integer [] sortedIntegers;
+    // private List<Integer> integersList;
+    // private List<Integer> sortedIntegersList;
+    private Employee[] employees;
+    private Employee[] employeesSorted;
+    private Employee[] employeesSortedByAge;
+    private HashMap<Integer, String> map;
+
+    @Before
+    public void initVariables() {
+
+        toSort = new int[] { 5, 1, 89, 255, 7, 88, 200, 123, 66 };
+        sortedInts = new int[] { 1, 5, 7, 66, 88, 89, 123, 200, 255 };
+        sortedRangeInts = new int[] { 5, 1, 89, 7, 88, 200, 255, 123, 66 };
+
+        // integers = new Integer[]
+        // { 5, 1, 89, 255, 7, 88, 200, 123, 66 };
+        // sortedIntegers = new Integer[]
+        // {1, 5, 7, 66, 88, 89, 123, 200, 255};
+        //
+        // integersList = Arrays.asList(new Integer[] { 5, 1, 89, 255, 7, 88, 200, 123, 66 });
+        // sortedIntegersList = Arrays.asList(new Integer[] {1, 5, 7, 66, 88, 89, 123, 200, 255});
+
+        employees = new Employee[] { new Employee("John", 23, 5000), new Employee("Steve", 26, 6000), new Employee("Frank", 33, 7000), new Employee("Earl", 43, 10000), new Employee("Jessica", 23, 4000), new Employee("Pearl", 33, 6000) };
+        employeesSorted = new Employee[] { new Employee("Earl", 43, 10000), new Employee("Frank", 33, 70000), new Employee("Jessica", 23, 4000), new Employee("John", 23, 5000), new Employee("Pearl", 33, 4000), new Employee("Steve", 26, 6000) };
+        employeesSortedByAge = new Employee[] { new Employee("John", 23, 5000), new Employee("Jessica", 23, 4000), new Employee("Steve", 26, 6000), new Employee("Frank", 33, 70000), new Employee("Pearl", 33, 4000), new Employee("Earl", 43, 10000) };
+
+        HashMap<Integer, String> map = new HashMap<>();
+        map.put(55, "John");
+        map.put(22, "Apple");
+        map.put(66, "Earl");
+        map.put(77, "Pearl");
+        map.put(12, "George");
+        map.put(6, "Rocky");
+
+    }
+
+    @Test
+    public void givenIntArray_whenUsingSort_thenSortedArray() {
+        Arrays.sort(toSort);
+
+        assertTrue(Arrays.equals(toSort, sortedInts));
+    }
+
+    @Test
+    public void givenIntegerArray_whenUsingSort_thenSortedArray() {
+        Integer[] integers = ArrayUtils.toObject(toSort);
+        Arrays.sort(integers, new Comparator<Integer>() {
+            @Override
+            public int compare(Integer a, Integer b) {
+                return a - b;
+            }
+        });
+
+        assertTrue(Arrays.equals(integers, ArrayUtils.toObject(sortedInts)));
+    }
+
+    @Test
+    public void givenArray_whenUsingSortWithLambdas_thenSortedArray() {
+        Integer[] integersToSort = ArrayUtils.toObject(toSort);
+        Arrays.sort(integersToSort, (a, b) -> {
+            return a - b;
+        });
+
+        assertTrue(Arrays.equals(integersToSort, ArrayUtils.toObject(sortedInts)));
+    }
+
+    @Test
+    public void givenEmpArray_SortEmpArray_thenSortedArrayinNaturalOrder() {
+        Arrays.sort(employees);
+
+        assertTrue(Arrays.equals(employees, employeesSorted));
+    }
+
+    @Test
+    public void givenIntArray_whenUsingRangeSort_thenRangeSortedArray() {
+        Arrays.sort(toSort, 3, 7);
+
+        assertTrue(Arrays.equals(toSort, sortedRangeInts));
+    }
+
+    @Test
+    public void givenIntArray_whenUsingParallelSort_thenArraySorted() {
+        Arrays.parallelSort(toSort);
+
+        assertTrue(Arrays.equals(toSort, sortedInts));
+    }
+
+    @Test
+    public void givenArrayObjects_whenUsingComparing_thenSortedArrayObjects() {
+        List<Employee> employeesList = Arrays.asList(employees);
+
+        employeesList.sort(Comparator.comparing(Employee::getAge));// .thenComparing(Employee::getName));
+
+        assertTrue(Arrays.equals(employeesList.toArray(), employeesSortedByAge));
+    }
+
+    @Test
+    public void givenList_whenUsingSort_thenSortedList() {
+        List<Integer> toSortList = Ints.asList(toSort);
+        Collections.sort(toSortList);
+
+        assertTrue(Arrays.equals(toSortList.toArray(), ArrayUtils.toObject(sortedInts)));
+    }
+
+    @Test
+    public void givenMap_whenSortingByKeys_thenSortedMap() {
+        Integer[] sortedKeys = new Integer[] { 6, 12, 22, 55, 66, 77 };
+
+        List<Map.Entry<Integer, String>> entries = new ArrayList<>(map.entrySet());
+        Collections.sort(entries, new Comparator<Entry<Integer, String>>() {
+            @Override
+            public int compare(Entry<Integer, String> o1, Entry<Integer, String> o2) {
+                return o1.getKey().compareTo(o2.getKey());
+            }
+        });
+        HashMap<Integer, String> sortedMap = new LinkedHashMap<>();
+        for (Map.Entry<Integer, String> entry : entries) {
+            sortedMap.put(entry.getKey(), entry.getValue());
+        }
+
+        assertTrue(Arrays.equals(sortedMap.keySet().toArray(), sortedKeys));
+    }
+
+    @Test
+    public void givenMap_whenSortingByValues_thenSortedMap() {
+        String[] sortedValues = new String[] { "Apple", "Earl", "George", "John", "Pearl", "Rocky" };
+
+        List<Map.Entry<Integer, String>> entries = new ArrayList<>(map.entrySet());
+        Collections.sort(entries, new Comparator<Entry<Integer, String>>() {
+            @Override
+            public int compare(Entry<Integer, String> o1, Entry<Integer, String> o2) {
+                return o1.getValue().compareTo(o2.getValue());
+            }
+        });
+        HashMap<Integer, String> sortedMap = new LinkedHashMap<>();
+        for (Map.Entry<Integer, String> entry : entries) {
+            sortedMap.put(entry.getKey(), entry.getValue());
+        }
+
+        assertTrue(Arrays.equals(sortedMap.values().toArray(), sortedValues));
+    }
+
+    @Test
+    public void givenSet_whenUsingSort_thenSortedSet() {
+        HashSet<Integer> integersSet = new LinkedHashSet<>(Ints.asList(toSort));
+        HashSet<Integer> descSortedIntegersSet = new LinkedHashSet<>(Arrays.asList(new Integer[] { 255, 200, 123, 89, 88, 66, 7, 5, 1 }));
+
+        ArrayList<Integer> list = new ArrayList<Integer>(integersSet);
+        Collections.sort(list, (i1, i2) -> {
+            return i2 - i1;
+        });
+        integersSet = new LinkedHashSet<>(list);
+
+        assertTrue(Arrays.equals(integersSet.toArray(), descSortedIntegersSet.toArray()));
+    }
+
+}

core-java/src/test/resources/file.txt

@@ -0,0 +1 @@
+baeldung.com