Merge remote-tracking branch 'upstream/master'

algorithms-miscellaneous-3/README.md

@@ -4,4 +4,3 @@
 - [Implementing Simple State Machines with Java Enums](https://www.baeldung.com/java-enum-simple-state-machine)
 - [Converting Between Roman and Arabic Numerals in Java](http://www.baeldung.com/java-convert-roman-arabic)
 - [Practical Java Examples of the Big O Notation](http://www.baeldung.com/java-algorithm-complexity)
-- [An Introduction to the Theory of Big-O Notation](http://www.baeldung.com/big-o-notation)

core-groovy-2/src/main/resources/articleEmail.template

@@ -0,0 +1,5 @@
+Dear <% out << (user) %>,
+Please read the requested article below.
+<% out << (articleText) %>
+From,
+<% out << (signature) %>

core-groovy-2/src/main/resources/email.template

@@ -0,0 +1,3 @@
+Dear $user,
+Thanks for subscribing our services.
+${signature}

core-groovy-2/src/test/groovy/com/baeldung/templateengine/TemplateEnginesUnitTest.groovy

@@ -0,0 +1,96 @@
+package com.baeldung.templateengine
+
+import groovy.text.SimpleTemplateEngine
+import groovy.text.StreamingTemplateEngine
+import groovy.text.GStringTemplateEngine
+import groovy.text.XmlTemplateEngine
+import groovy.text.XmlTemplateEngine
+import groovy.text.markup.MarkupTemplateEngine
+import groovy.text.markup.TemplateConfiguration
+
+class TemplateEnginesUnitTest extends GroovyTestCase {
+    
+    def bindMap = [user: "Norman", signature: "Baeldung"]
+    
+    void testSimpleTemplateEngine() {
+        def smsTemplate = 'Dear <% print user %>, Thanks for reading our Article. ${signature}'
+        def smsText = new SimpleTemplateEngine().createTemplate(smsTemplate).make(bindMap)
+
+        assert smsText.toString() == "Dear Norman, Thanks for reading our Article. Baeldung"
+    }
+    
+    void testStreamingTemplateEngine() {
+        def articleEmailTemplate = new File('src/main/resources/articleEmail.template')
+        bindMap.articleText = """1. Overview
+This is a tutorial article on Template Engines""" //can be a string larger than 64k
+        
+        def articleEmailText = new StreamingTemplateEngine().createTemplate(articleEmailTemplate).make(bindMap)
+        
+        assert articleEmailText.toString() == """Dear Norman,
+Please read the requested article below.
+1. Overview
+This is a tutorial article on Template Engines
+From,
+Baeldung"""
+        
+    }
+    
+    void testGStringTemplateEngine() {
+        def emailTemplate = new File('src/main/resources/email.template')
+        def emailText = new GStringTemplateEngine().createTemplate(emailTemplate).make(bindMap)
+        
+        assert emailText.toString() == "Dear Norman,\nThanks for subscribing our services.\nBaeldung"
+    }
+    
+    void testXmlTemplateEngine() {
+        def emailXmlTemplate = '''<xs xmlns:gsp='groovy-server-pages'>
+                                      <gsp:scriptlet>def emailContent = "Thanks for subscribing our services."</gsp:scriptlet>
+                                      <email>
+                                          <greet>Dear ${user}</greet>
+                                          <content><gsp:expression>emailContent</gsp:expression></content>
+                                          <signature>${signature}</signature>
+                                      </email>
+                                  </xs>'''
+        def emailXml = new XmlTemplateEngine().createTemplate(emailXmlTemplate).make(bindMap)
+        println emailXml.toString()
+    }
+    
+    void testMarkupTemplateEngineHtml() {
+        def emailHtmlTemplate = """html {
+                                       head {
+                                           title('Service Subscription Email')
+                                       }
+                                       body {
+                                           p('Dear Norman')
+                                           p('Thanks for subscribing our services.')
+                                           p('Baeldung')
+                                       }
+                                   }"""
+        
+        
+        def emailHtml = new MarkupTemplateEngine().createTemplate(emailHtmlTemplate).make()
+        println emailHtml.toString()
+        
+    }
+    
+    void testMarkupTemplateEngineXml() {
+        def emailXmlTemplate = """xmlDeclaration()  
+                                      xs{
+                                          email {
+                                              greet('Dear Norman')
+                                              content('Thanks for subscribing our services.')
+                                              signature('Baeldung')
+                                          }  
+                                      }
+                               """
+        TemplateConfiguration config = new TemplateConfiguration()
+        config.autoIndent = true
+        config.autoEscape = true
+        config.autoNewLine = true
+
+        def emailXml = new MarkupTemplateEngine(config).createTemplate(emailXmlTemplate).make()
+        
+        println emailXml.toString()
+    }
+    
+}

core-java-arrays/README.MD

@@ -0,0 +1,3 @@
+## Relevant Articles
+
+- [Extending an Array’s Length](https://www.baeldung.com/java-array-add-element-at-the-end)

core-java-modules/core-java-11/pom.xml

@@ -1,4 +1,6 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+<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>
@@ -12,7 +14,7 @@
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
-        <relativePath>../../</relativePath>
+        <relativePath>../..</relativePath>
     </parent>
 
     <dependencies>
@@ -21,6 +23,12 @@
             <artifactId>guava</artifactId>
             <version>${guava.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -41,6 +49,7 @@
         <maven.compiler.source.version>11</maven.compiler.source.version>
         <maven.compiler.target.version>11</maven.compiler.target.version>
         <guava.version>27.1-jre</guava.version>
+        <assertj.version>3.11.1</assertj.version>
     </properties>
 
 </project>

core-java-modules/core-java-11/src/main/java/com/baeldung/predicate/not/Person.java

@@ -0,0 +1,19 @@
+package com.baeldung.predicate.not;
+
+public class Person {
+    private static final int ADULT_AGE = 18;
+
+    private int age;
+
+    public Person(int age) {
+        this.age = age;
+    }
+
+    public boolean isAdult() {
+        return age >= ADULT_AGE;
+    }
+
+    public boolean isNotAdult() {
+        return !isAdult();
+    }
+}

core-java-modules/core-java-11/src/test/java/com/baeldung/AppUnitTest.java

@@ -7,7 +7,7 @@ import junit.framework.TestSuite;
 /**
  * Unit test for simple App.
  */
-public class AppTest 
+public class AppUnitTest
     extends TestCase
 {
     /**
@@ -15,7 +15,7 @@ public class AppTest
      *
      * @param testName name of the test case
      */
-    public AppTest( String testName )
+    public AppUnitTest(String testName )
     {
         super( testName );
     }
@@ -25,7 +25,7 @@ public class AppTest
      */
     public static Test suite()
     {
-        return new TestSuite( AppTest.class );
+        return new TestSuite( AppUnitTest.class );
     }
 
     /**

core-java-modules/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpClientUnitTest.java

@@ -32,7 +32,7 @@ import java.util.stream.Collectors;
 
 import org.junit.jupiter.api.Test;
 
-public class HttpClientTest {
+public class HttpClientUnitTest {
 
     @Test
     public void shouldReturnSampleDataContentWhenConnectViaSystemProxy() throws IOException, InterruptedException, URISyntaxException {

core-java-modules/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpRequestUnitTest.java

@@ -19,7 +19,7 @@ import java.time.Duration;
 
 import org.junit.Test;
 
-public class HttpRequestTest {
+public class HttpRequestUnitTest {
 
     @Test
     public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, InterruptedException, URISyntaxException {

core-java-modules/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpResponseUnitTest.java

@@ -14,7 +14,7 @@ import java.net.http.HttpResponse;
 
 import org.junit.Test;
 
-public class HttpResponseTest {
+public class HttpResponseUnitTest {
 
     @Test
     public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, InterruptedException, URISyntaxException {

core-java-modules/core-java-11/src/test/java/com/baeldung/predicate/not/PersonUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.predicate.not;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static java.util.function.Predicate.not;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class PersonUnitTest {
+    private List<Person> people;
+
+    @BeforeEach
+    void preparePeople() {
+        people = Arrays.asList(
+          new Person(1),
+          new Person(18),
+          new Person(2)
+        );
+    }
+
+    @Test
+    void givenPeople_whenFilterIsAdult_thenOneResult() {
+        List<Person> adults = people.stream()
+          .filter(Person::isAdult)
+          .collect(Collectors.toList());
+
+        assertThat(adults).size().isEqualTo(1);
+    }
+
+    @Test
+    void givenPeople_whenFilterIsAdultNegated_thenTwoResults() {
+        List<Person> nonAdults = people.stream()
+          .filter(person -> !person.isAdult())
+          .collect(Collectors.toList());
+
+        assertThat(nonAdults).size().isEqualTo(2);
+    }
+
+    @Test
+    void givenPeople_whenFilterIsNotAdult_thenTwoResults() {
+        List<Person> nonAdults = people.stream()
+          .filter(Person::isNotAdult)
+          .collect(Collectors.toList());
+
+        assertThat(nonAdults).size().isEqualTo(2);
+    }
+
+    @Test
+    void givenPeople_whenFilterNotIsAdult_thenTwoResults() {
+        List<Person> nonAdults = people.stream()
+          .filter(not(Person::isAdult))
+          .collect(Collectors.toList());
+
+        assertThat(nonAdults).size().isEqualTo(2);
+    }
+}

core-java-modules/core-java-12/src/test/java/com/baeldung/string/StringAPITest.java

@@ -0,0 +1,43 @@
+package com.baeldung.string;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.Test;
+
+public class StringAPITest {
+
+    @Test
+    public void whenPositiveArgument_thenReturnIndentedString() {
+        String multilineStr = "This is\na multiline\nstring.";
+        String outputStr = "   This is\n   a multiline\n   string.\n";
+
+        String postIndent = multilineStr.indent(3);
+
+        assertThat(postIndent, equalTo(outputStr));
+    }
+
+    @Test
+    public void whenNegativeArgument_thenReturnReducedIndentedString() {
+        String multilineStr = "   This is\n   a multiline\n   string.";
+        String outputStr = " This is\n a multiline\n string.\n";
+
+        String postIndent = multilineStr.indent(-2);
+
+        assertThat(postIndent, equalTo(outputStr));
+    }
+
+    @Test
+    public void whenTransformUsingLamda_thenReturnTransformedString() {
+        String result = "hello".transform(input -> input + " world!");
+
+        assertThat(result, equalTo("hello world!"));
+    }
+
+    @Test
+    public void whenTransformUsingParseInt_thenReturnInt() {
+        int result = "42".transform(Integer::parseInt);
+
+        assertThat(result, equalTo(42));
+    }
+}

core-java-modules/core-java-8-2/README.md

@@ -3,4 +3,5 @@
 ## Core Java 8 Cookbooks and Examples (part 2)
 
 ### Relevant Articles: 
-- [Anonymous Classes in Java](http://www.baeldung.com/)
+- [Anonymous Classes in Java](https://www.baeldung.com/java-anonymous-classes)
+- [Run JAR Application With Command Line Arguments](https://www.baeldung.com/java-run-jar-with-arguments)

core-java-modules/core-java-9/README.md

@@ -20,7 +20,6 @@
 - [Multi-Release Jar Files](https://www.baeldung.com/java-multi-release-jar)
 - [Ahead of Time Compilation (AoT)](https://www.baeldung.com/ahead-of-time-compilation)
 - [Java 9 Process API Improvements](https://www.baeldung.com/java-9-process-api)
-- [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)
 - [Java 9 java.util.Objects Additions](https://www.baeldung.com/java-9-objects-new)
 - [Java 9 Reactive Streams](https://www.baeldung.com/java-9-reactive-streams)
 - [Java 9 Optional API Additions](https://www.baeldung.com/java-9-optional)
@@ -31,4 +30,4 @@
 - [A Guide to Java 9 Modularity](https://www.baeldung.com/java-9-modularity)
 - [Java 9 Platform Module API](https://www.baeldung.com/java-9-module-api)
 - [Java 9 Platform Logging API](https://www.baeldung.com/java-9-logging-api)
-
+- [Filtering a Stream of Optionals in Java](https://www.baeldung.com/java-filter-stream-of-optional)

core-java-modules/core-java-collections-array-list/README.md

@@ -0,0 +1,10 @@
+=========
+
+## Core Java Collections Array List Cookbooks and Examples
+
+### Relevant Articles: 
+- [Immutable ArrayList in Java](http://www.baeldung.com/java-immutable-list)
+- [Guide to the Java ArrayList](http://www.baeldung.com/java-arraylist)
+- [Add Multiple Items to an Java ArrayList](http://www.baeldung.com/java-add-items-array-list)
+- [ClassCastException: Arrays$ArrayList cannot be cast to ArrayList](https://www.baeldung.com/java-classcastexception-arrays-arraylist)
+- [Multi Dimensional ArrayList in Java](https://www.baeldung.com/java-multi-dimensional-arraylist)

core-java-modules/core-java-collections-array-list/pom.xml

@@ -0,0 +1,46 @@
+<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>
+    <artifactId>core-java-collections-array-list</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-collections-array-list</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <commons-lang3.version>3.8.1</commons-lang3.version>
+        <assertj.version>3.11.1</assertj.version>
+    </properties>
+</project>

core-java-modules/core-java-collections-array-list/src/main/java/com/baeldung/java/list/Flower.java

@@ -0,0 +1,28 @@
+package com.baeldung.java.list;
+
+public class Flower {
+
+    private String name;
+    private int petals;
+
+    public Flower(String name, int petals) {
+        this.name = name;
+        this.petals = petals;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getPetals() {
+        return petals;
+    }
+
+    public void setPetals(int petals) {
+        this.petals = petals;
+    }
+}

core-java-modules/core-java-collections-array-list/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

core-java-modules/core-java-collections-list-2/README.md

@@ -0,0 +1,17 @@
+=========
+
+## Core Java Collections List Cookbooks and Examples
+
+### Relevant Articles: 
+- [Check If Two Lists are Equal in Java](http://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
+- [Java 8 Streams: Find Items From One List Based On Values From Another List](https://www.baeldung.com/java-streams-find-list-items)
+- [A Guide to the Java LinkedList](http://www.baeldung.com/java-linkedlist)
+- [Java List UnsupportedOperationException](http://www.baeldung.com/java-list-unsupported-operation-exception)
+- [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
+- [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
+- [Flattening Nested Collections in Java](http://www.baeldung.com/java-flatten-nested-collections)
+- [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)
+- [Determine If All Elements Are the Same in a Java List](https://www.baeldung.com/java-list-all-equal)
+- [List of Primitive Integer Values in Java](https://www.baeldung.com/java-list-primitive-int)
+- [Performance Comparison of Primitive Lists in Java](https://www.baeldung.com/java-list-primitive-performance)
+- [Filtering a Java Collection by a List](https://www.baeldung.com/java-filter-collection-by-list)

core-java-modules/core-java-collections-list-2/pom.xml

@@ -0,0 +1,76 @@
+<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>
+    <artifactId>core-java-collections-list-2</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-collections-list-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>net.sf.trove4j</groupId>
+            <artifactId>trove4j</artifactId>
+            <version>${trove4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>it.unimi.dsi</groupId>
+            <artifactId>fastutil</artifactId>
+            <version>${fastutil.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>colt</groupId>
+            <artifactId>colt</artifactId>
+            <version>${colt.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <commons-lang3.version>3.8.1</commons-lang3.version>
+        <assertj.version>3.11.1</assertj.version>
+		<trove4j.version>3.0.2</trove4j.version>
+		<fastutil.version>8.1.0</fastutil.version>
+		<colt.version>1.2.0</colt.version>
+    </properties>
+</project>

core-java-modules/core-java-collections-list-2/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

core-java-modules/core-java-collections-list/README.md

@@ -3,31 +3,14 @@
 ## Core Java Collections List Cookbooks and Examples
 
 ### Relevant Articles: 
-- [Immutable ArrayList in Java](http://www.baeldung.com/java-immutable-list)
-- [Guide to the Java ArrayList](http://www.baeldung.com/java-arraylist)
 - [Java – Get Random Item/Element From a List](http://www.baeldung.com/java-random-list-element)
 - [Removing all nulls from a List in Java](http://www.baeldung.com/java-remove-nulls-from-list)
 - [Removing all duplicates from a List in Java](http://www.baeldung.com/java-remove-duplicates-from-list)
 - [How to TDD a List Implementation in Java](http://www.baeldung.com/java-test-driven-list)
 - [Iterating Backward Through a List](http://www.baeldung.com/java-list-iterate-backwards)
-- [Add Multiple Items to an Java ArrayList](http://www.baeldung.com/java-add-items-array-list)
 - [Remove the First Element from a List](http://www.baeldung.com/java-remove-first-element-from-list)
 - [How to Find an Element in a List with Java](http://www.baeldung.com/find-list-element-java)
 - [Copy a List to Another List in Java](http://www.baeldung.com/java-copy-list-to-another)
 - [Finding Max/Min of a List or Collection](http://www.baeldung.com/java-collection-min-max)
 - [Collections.emptyList() vs. New List Instance](https://www.baeldung.com/java-collections-emptylist-new-list)
 - [Remove All Occurrences of a Specific Value from a List](https://www.baeldung.com/java-remove-value-from-list)
-- [Check If Two Lists are Equal in Java](http://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
-- [Java 8 Streams: Find Items From One List Based On Values From Another List](https://www.baeldung.com/java-streams-find-list-items)
-- [A Guide to the Java LinkedList](http://www.baeldung.com/java-linkedlist)
-- [Java List UnsupportedOperationException](http://www.baeldung.com/java-list-unsupported-operation-exception)
-- [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
-- [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
-- [ClassCastException: Arrays$ArrayList cannot be cast to ArrayList](https://www.baeldung.com/java-classcastexception-arrays-arraylist)
-- [Flattening Nested Collections in Java](http://www.baeldung.com/java-flatten-nested-collections)
-- [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)
-- [Multi Dimensional ArrayList in Java](https://www.baeldung.com/java-multi-dimensional-arraylist)
-- [Determine If All Elements Are the Same in a Java List](https://www.baeldung.com/java-list-all-equal)
-- [List of Primitive Integer Values in Java](https://www.baeldung.com/java-list-primitive-int)
-- [Performance Comparison of Primitive Lists in Java](https://www.baeldung.com/java-list-primitive-performance)
-- [Filtering a Java Collection by a List](https://www.baeldung.com/java-filter-collection-by-list)

core-java-modules/core-java-collections-list/pom.xml

@@ -36,42 +36,12 @@
             <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
-
-        <dependency>
-            <groupId>net.sf.trove4j</groupId>
-            <artifactId>trove4j</artifactId>
-            <version>${trove4j.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>it.unimi.dsi</groupId>
-            <artifactId>fastutil</artifactId>
-            <version>${fastutil.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>colt</groupId>
-            <artifactId>colt</artifactId>
-            <version>${colt.version}</version>
-        </dependency>
-
-        <dependency>
-            <groupId>org.openjdk.jmh</groupId>
-            <artifactId>jmh-core</artifactId>
-            <version>${jmh-core.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.openjdk.jmh</groupId>
-            <artifactId>jmh-generator-annprocess</artifactId>
-            <version>${jmh-core.version}</version>
-        </dependency>
     </dependencies>
 
     <properties>
         <commons-collections4.version>4.1</commons-collections4.version>
         <commons-lang3.version>3.8.1</commons-lang3.version>
-        <avaitility.version>1.7.0</avaitility.version>
         <assertj.version>3.11.1</assertj.version>
 		<trove4j.version>3.0.2</trove4j.version>
-		<fastutil.version>8.1.0</fastutil.version>
-		<colt.version>1.2.0</colt.version>
     </properties>
 </project>

core-java-modules/core-java-io/README.md

@@ -40,3 +40,4 @@
 - [How to Write to a CSV File in Java](https://www.baeldung.com/java-csv)
 - [List Files in a Directory in Java](https://www.baeldung.com/java-list-directory-files)
 - [Java InputStream to Byte Array and ByteBuffer](https://www.baeldung.com/convert-input-stream-to-array-of-bytes)
+- [Introduction to the Java NIO Selector](https://www.baeldung.com/java-nio-selector)

core-java-modules/core-java-jpms/decoupling-pattern1/consumermodule/pom.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>
+    <artifactId>consumermodule</artifactId>
+    <packaging>jar</packaging>
+    <version>1.0</version>
+    
+    <parent>
+        <groupId>com.baeldung.decoupling-pattern1</groupId>
+        <artifactId>decoupling-pattern1</artifactId>
+        <version>1.0</version>
+    </parent>
+    
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+    
+    <dependencies>
+        <dependency>
+            <groupId>com.baeldung.servicemodule</groupId>
+            <artifactId>servicemodule</artifactId>
+            <version>1.0</version>           
+        </dependency>
+    </dependencies>
+</project>

core-java-modules/core-java-jpms/decoupling-pattern1/consumermodule/src/main/java/com/baeldung/consumermodule/Application.java

@@ -0,0 +1,13 @@
+package com.baeldung.consumermodule;
+
+import com.baeldung.servicemodule.external.TextService;
+import com.baeldung.servicemodule.external.TextServiceFactory;
+
+public class Application {
+    
+    public static void main(String args[]) {
+        TextService textService = TextServiceFactory.getTextService("lowercase");
+        System.out.println(textService.processText("Hello from Baeldung!"));
+    }
+    
+}

core-java-modules/core-java-jpms/decoupling-pattern1/consumermodule/src/main/java/module-info.java

@@ -0,0 +1,3 @@
+module com.baeldung.consumermodule {
+    requires com.baeldung.servicemodule;
+}

core-java-modules/core-java-jpms/decoupling-pattern1/pom.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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.decoupling-pattern1</groupId>
+    <artifactId>decoupling-pattern1</artifactId>
+    <version>1.0</version>
+    <packaging>pom</packaging>
+    
+    <modules>
+        <module>servicemodule</module>
+        <module>consumermodule</module>
+    </modules>
+    
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-compiler-plugin</artifactId>
+                    <version>3.8.0</version>
+                    <configuration>
+                        <source>11</source>
+                        <target>11</target>
+                    </configuration>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+    
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+</project>

core-java-modules/core-java-jpms/decoupling-pattern1/servicemodule/pom.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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.servicemodule</groupId>
+    <artifactId>servicemodule</artifactId>
+    <packaging>jar</packaging>
+    
+    <parent>
+        <groupId>com.baeldung.decoupling-pattern1</groupId>
+        <artifactId>decoupling-pattern1</artifactId>
+        <version>1.0</version>
+    </parent>
+    
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+   
+</project>

core-java-modules/core-java-jpms/decoupling-pattern1/servicemodule/src/main/java/com/baeldung/servicemodule/external/TextService.java

@@ -0,0 +1,7 @@
+package com.baeldung.servicemodule.external;
+
+public interface TextService {
+    
+    String processText(String text);
+    
+}

core-java-modules/core-java-jpms/decoupling-pattern1/servicemodule/src/main/java/com/baeldung/servicemodule/external/TextServiceFactory.java

@@ -0,0 +1,14 @@
+package com.baeldung.servicemodule.external;
+
+import com.baeldung.servicemodule.internal.LowercaseTextService;
+import com.baeldung.servicemodule.internal.UppercaseTextService;
+
+public class TextServiceFactory {
+    
+    private TextServiceFactory() {}
+    
+    public static TextService getTextService(String name) {
+        return name.equalsIgnoreCase("lowercase") ? new LowercaseTextService(): new UppercaseTextService();
+    }
+    
+}

core-java-modules/core-java-jpms/decoupling-pattern1/servicemodule/src/main/java/com/baeldung/servicemodule/internal/LowercaseTextService.java

@@ -0,0 +1,12 @@
+package com.baeldung.servicemodule.internal;
+
+import com.baeldung.servicemodule.external.TextService;
+
+public class LowercaseTextService implements TextService {
+
+    @Override
+    public String processText(String text) {
+        return text.toLowerCase();
+    }
+    
+}

core-java-modules/core-java-jpms/decoupling-pattern1/servicemodule/src/main/java/com/baeldung/servicemodule/internal/UppercaseTextService.java

@@ -0,0 +1,12 @@
+package com.baeldung.servicemodule.internal;
+
+import com.baeldung.servicemodule.external.TextService;
+
+public class UppercaseTextService implements TextService {
+    
+    @Override
+    public String processText(String text) {
+        return text.toUpperCase();
+    }
+    
+}

core-java-modules/core-java-jpms/decoupling-pattern1/servicemodule/src/main/java/module-info.java

@@ -0,0 +1,3 @@
+module com.baeldung.servicemodule {
+    exports com.baeldung.servicemodule.external;
+}

core-java-modules/core-java-jpms/decoupling-pattern2/consumermodule/pom.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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">
+    <parent>
+        <artifactId>com.baeldung.decoupling-pattern2</artifactId>
+        <groupId>decoupling-pattern2</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.baeldung.consumermodule</groupId>
+    <artifactId>consumermodule</artifactId>
+    <version>1.0</version>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.baeldung.servicemodule</groupId>
+            <artifactId>servicemodule</artifactId>
+            <version>1.0</version>
+        </dependency>
+        <dependency>
+            <groupId>com.baeldung.providermodule</groupId>
+            <artifactId>providermodule</artifactId>
+            <version>1.0</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

core-java-modules/core-java-jpms/decoupling-pattern2/consumermodule/src/main/java/com/baeldung/consumermodule/Application.java

@@ -0,0 +1,15 @@
+package com.baeldung.consumermodule;
+
+import com.baeldung.servicemodule.TextService;
+
+import java.util.ServiceLoader;
+
+public class Application {
+
+    public static void main(String[] args) {
+        ServiceLoader<TextService> services = ServiceLoader.load(TextService.class);
+        for (final TextService service: services) {
+            System.out.println("The service " + service.getClass().getSimpleName() + " says: " + service.parseText("Hello from Baeldung!"));
+        }
+    }
+}

core-java-modules/core-java-jpms/decoupling-pattern2/consumermodule/src/main/java/module-info.java

@@ -0,0 +1,4 @@
+module com.baeldung.consumermodule {
+    requires com.baeldung.servicemodule;
+    uses com.baeldung.servicemodule.TextService;
+}

core-java-modules/core-java-jpms/decoupling-pattern2/pom.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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.decoupling-pattern2</groupId>
+    <artifactId>decoupling-pattern2</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>servicemodule</module>
+        <module>providermodule</module>
+        <module>consumermodule</module>
+    </modules>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-compiler-plugin</artifactId>
+                    <version>3.8.0</version>
+                    <configuration>
+                        <source>11</source>
+                        <target>11</target>
+                    </configuration>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+
+</project>

core-java-modules/core-java-jpms/decoupling-pattern2/providermodule/pom.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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.providermodule</groupId>
+    <artifactId>providermodule</artifactId>
+    <version>1.0</version>
+
+    <parent>
+        <artifactId>com.baeldung.decoupling-pattern2</artifactId>
+        <groupId>decoupling-pattern2</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.baeldung.servicemodule</groupId>
+            <artifactId>servicemodule</artifactId>
+            <version>1.0</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

core-java-modules/core-java-jpms/decoupling-pattern2/providermodule/src/main/java/com/baeldung/providermodule/LowercaseTextService.java

@@ -0,0 +1,10 @@
+package com.baeldung.providermodule;
+
+import com.baeldung.servicemodule.TextService;
+
+public class LowercaseTextService implements TextService {
+    @Override
+    public String parseText(String text) {
+        return text.toLowerCase();
+    }
+}

core-java-modules/core-java-jpms/decoupling-pattern2/providermodule/src/main/java/module-info.java

@@ -0,0 +1,4 @@
+module com.baeldung.providermodule {
+    requires com.baeldung.servicemodule;
+    provides com.baeldung.servicemodule.TextService with com.baeldung.providermodule.LowercaseTextService;
+}

core-java-modules/core-java-jpms/decoupling-pattern2/servicemodule/pom.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>
+    <parent>
+        <artifactId>>com.baeldung.decoupling-pattern2</artifactId>
+        <groupId>decoupling-pattern2</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <groupId>com.baeldung.servicemodule</groupId>
+    <artifactId>servicemodule</artifactId>
+    <version>1.0</version>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

core-java-modules/core-java-jpms/decoupling-pattern2/servicemodule/src/main/java/com/baeldung/servicemodule/TextService.java

@@ -0,0 +1,6 @@
+package com.baeldung.servicemodule;
+
+public interface TextService {
+
+    String parseText(String text);
+}

core-java-modules/core-java-jpms/decoupling-pattern2/servicemodule/src/main/java/module-info.java

@@ -0,0 +1,3 @@
+module com.baeldung.servicemodule {
+    exports com.baeldung.servicemodule;
+}

core-java-modules/core-java-reflection/README.MD

@@ -0,0 +1,3 @@
+## Relevant Articles
+
+- [Void Type in Java](https://www.baeldung.com/java-void-type)

core-java-modules/core-java/README.md

@@ -51,3 +51,4 @@
 - [Java Bitwise Operators](https://www.baeldung.com/java-bitwise-operators)
 - [Guide to Creating and Running a Jar File in Java](https://www.baeldung.com/java-create-jar)
 - [Making a JSON POST Request With HttpURLConnection](https://www.baeldung.com/httpurlconnection-post)
+- [Convert Hex to ASCII in Java](https://www.baeldung.com/java-convert-hex-to-ascii)

core-java-modules/pre-jpms/README.MD

@@ -0,0 +1,3 @@
+## Relevant Articles
+
+- [Java 9 Migration Issues and Resolutions](https://www.baeldung.com/java-9-migration-issue)

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/AmountBasedDiscountPolicy.java

@@ -0,0 +1,15 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+
+public class AmountBasedDiscountPolicy implements DiscountPolicy {
+    @Override
+    public double discount(Order order) {
+        if (order.totalCost()
+            .isGreaterThan(Money.of(CurrencyUnit.USD, 500.00))) {
+            return 0.10;
+        } else
+            return 0;
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/DiscountPolicy.java

@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public interface DiscountPolicy {
+    double discount(Order order);
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/FlatDiscountPolicy.java

@@ -0,0 +1,8 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public class FlatDiscountPolicy implements DiscountPolicy {
+    @Override
+    public double discount(Order order) {
+        return 0.01;
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/Order.java

@@ -0,0 +1,29 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import java.math.RoundingMode;
+import java.util.List;
+
+import org.joda.money.Money;
+
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.OrderVisitor;
+import com.baeldung.ddd.order.doubledispatch.visitor.Visitable;
+
+public class Order extends com.baeldung.ddd.order.Order implements Visitable<OrderVisitor> {
+    public Order(List<OrderLine> orderLines) {
+        super(orderLines);        
+    }
+
+    public Money totalCost(SpecialDiscountPolicy discountPolicy) {
+        return totalCost().multipliedBy(1 - applyDiscountPolicy(discountPolicy), RoundingMode.HALF_UP);
+    }
+
+    protected double applyDiscountPolicy(SpecialDiscountPolicy discountPolicy) {
+        return discountPolicy.discount(this);
+    }
+    
+    @Override
+    public void accept(OrderVisitor visitor) {
+        visitor.visit(this);        
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/SpecialDiscountPolicy.java

@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public interface SpecialDiscountPolicy extends DiscountPolicy {
+    double discount(SpecialOrder order);
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/SpecialOrder.java

@@ -0,0 +1,36 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import java.util.List;
+
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.OrderVisitor;
+
+public class SpecialOrder extends Order {
+
+    private boolean eligibleForExtraDiscount;
+
+    public SpecialOrder(List<OrderLine> orderLines) {
+        super(orderLines);
+        this.eligibleForExtraDiscount = false;
+    }
+
+    public SpecialOrder(List<OrderLine> orderLines, boolean eligibleForSpecialDiscount) {
+        super(orderLines);
+        this.eligibleForExtraDiscount = eligibleForSpecialDiscount;
+    }
+
+    public boolean isEligibleForExtraDiscount() {
+        return eligibleForExtraDiscount;
+    }
+
+    @Override
+    protected double applyDiscountPolicy(SpecialDiscountPolicy discountPolicy) {
+        return discountPolicy.discount(this);
+    }
+
+    @Override
+    public void accept(OrderVisitor visitor) {
+        visitor.visit(this);
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/visitor/HtmlOrderViewCreator.java

@@ -0,0 +1,24 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public class HtmlOrderViewCreator implements OrderVisitor {
+    
+    private String html;
+    
+    public String getHtml() {
+        return html;
+    }
+
+    @Override
+    public void visit(Order order) {
+        html = String.format("<p>Regular order total cost: %s</p>", order.totalCost());
+    }
+
+    @Override
+    public void visit(SpecialOrder order) {
+        html = String.format("<h1>Special Order</h1><p>total cost: %s</p>", order.totalCost());
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/visitor/OrderVisitor.java

@@ -0,0 +1,9 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public interface OrderVisitor {
+    void visit(Order order);
+    void visit(SpecialOrder order);
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/visitor/Visitable.java

@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+public interface Visitable<V> {
+    void accept(V visitor);
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaOrder.java

@@ -92,7 +92,7 @@ class JpaOrder {
     }
 
     void removeLineItem(int line) {
-        JpaOrderLine removedLine = orderLines.remove(line);
+        orderLines.remove(line);
     }
 
     void setCurrencyUnit(String currencyUnit) {

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaProduct.java

@@ -15,7 +15,7 @@ class JpaProduct {
     public JpaProduct(BigDecimal price, String currencyUnit) {
         super();
         this.price = price;
-        currencyUnit = currencyUnit;
+        this.currencyUnit = currencyUnit;
     }
 
     @Override

ddd/src/test/java/com/baeldung/ddd/order/OrderFixtureUtils.java

@@ -0,0 +1,17 @@
+package com.baeldung.ddd.order;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+
+public class OrderFixtureUtils {
+    public static List<OrderLine> anyOrderLines() {
+        return Arrays.asList(new OrderLine(new Product(Money.of(CurrencyUnit.USD, 100)), 1));
+    }
+
+    public static List<OrderLine> orderLineItemsWorthNDollars(int totalCost) {
+        return Arrays.asList(new OrderLine(new Product(Money.of(CurrencyUnit.USD, totalCost)), 1));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/DoubleDispatchDiscountPolicyUnitTest.java

@@ -0,0 +1,77 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.OrderFixtureUtils;
+
+public class DoubleDispatchDiscountPolicyUnitTest {
+    // @formatter:off
+    @DisplayName(
+        "given regular order with items worth $100 total, " +
+        "when apply 10% discount policy, " +
+        "then cost after discount is $90"
+        )
+    // @formatter:on
+    @Test
+    void test() throws Exception {
+        // given
+        Order order = new Order(OrderFixtureUtils.orderLineItemsWorthNDollars(100));
+        SpecialDiscountPolicy discountPolicy = new SpecialDiscountPolicy() {
+
+            @Override
+            public double discount(Order order) {
+                return 0.10;
+            }
+
+            @Override
+            public double discount(SpecialOrder order) {
+                return 0;
+            }
+        };
+
+        // when
+        Money totalCostAfterDiscount = order.totalCost(discountPolicy);
+
+        // then
+        assertThat(totalCostAfterDiscount).isEqualTo(Money.of(CurrencyUnit.USD, 90));
+    }
+
+    // @formatter:off
+    @DisplayName(
+        "given special order eligible for extra discount with items worth $100 total, " +
+        "when apply 20% discount policy for extra discount orders, " +
+        "then cost after discount is $80"
+        )
+    // @formatter:on
+    @Test
+    void test1() throws Exception {
+        // given
+        boolean eligibleForExtraDiscount = true;
+        Order order = new SpecialOrder(OrderFixtureUtils.orderLineItemsWorthNDollars(100), eligibleForExtraDiscount);
+        SpecialDiscountPolicy discountPolicy = new SpecialDiscountPolicy() {
+
+            @Override
+            public double discount(Order order) {
+                return 0;
+            }
+
+            @Override
+            public double discount(SpecialOrder order) {
+                if (order.isEligibleForExtraDiscount())
+                    return 0.20;
+                return 0.10;
+            }
+        };
+
+        // when
+        Money totalCostAfterDiscount = order.totalCost(discountPolicy);
+
+        // then
+        assertThat(totalCostAfterDiscount).isEqualTo(Money.of(CurrencyUnit.USD, 80.00));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/HtmlOrderViewCreatorUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.OrderFixtureUtils;
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.HtmlOrderViewCreator;
+
+public class HtmlOrderViewCreatorUnitTest {
+    // @formatter:off 
+    @DisplayName(
+            "given collection of regular and special orders, " +
+            "when create HTML view using visitor for each order, " +
+            "then the dedicated view is created for each order"   
+        )
+    // @formatter:on
+    @Test
+    void test() throws Exception {
+        // given
+        List<OrderLine> anyOrderLines = OrderFixtureUtils.anyOrderLines();
+        List<Order> orders = Arrays.asList(new Order(anyOrderLines), new SpecialOrder(anyOrderLines));
+        HtmlOrderViewCreator htmlOrderViewCreator = new HtmlOrderViewCreator();
+
+        // when
+        orders.get(0)
+            .accept(htmlOrderViewCreator);
+        String regularOrderHtml = htmlOrderViewCreator.getHtml();
+        orders.get(1)
+            .accept(htmlOrderViewCreator);
+        String specialOrderHtml = htmlOrderViewCreator.getHtml();
+
+        // then
+        assertThat(regularOrderHtml).containsPattern("<p>Regular order total cost: .*</p>");
+        assertThat(specialOrderHtml).containsPattern("<h1>Special Order</h1><p>total cost: .*</p>");
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/MethodOverloadExampleUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.List;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.OrderFixtureUtils;
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.SpecialDiscountPolicy;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public class MethodOverloadExampleUnitTest {
+// @formatter:off
+@DisplayName(
+    "given discount policy accepting special orders, " +
+    "when apply the policy on special order declared as regular order, " +
+    "then regular discount method is used"
+    )
+// @formatter:on    
+    @Test
+    void test() throws Exception {
+        // given
+        SpecialDiscountPolicy specialPolicy = new SpecialDiscountPolicy() {
+            @Override
+            public double discount(Order order) {
+                return 0.01;
+            }
+
+            @Override
+            public double discount(SpecialOrder order) {
+                return 0.10;
+            }
+        };
+        Order specialOrder = new SpecialOrder(anyOrderLines());
+
+        // when
+        double discount = specialPolicy.discount(specialOrder);
+
+        // then
+        assertThat(discount).isEqualTo(0.01);
+    }
+
+    private List<OrderLine> anyOrderLines() {
+        return OrderFixtureUtils.anyOrderLines();
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/SingleDispatchDiscountPolicyUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.OrderFixtureUtils;
+
+public class SingleDispatchDiscountPolicyUnitTest {
+    // @formatter:off
+    @DisplayName(
+        "given two discount policies, " +
+        "when use these policies, " +
+        "then single dispatch chooses the implementation based on runtime type"
+        )
+    // @formatter:on    
+    @Test
+    void test() throws Exception {
+        // given
+        DiscountPolicy flatPolicy = new FlatDiscountPolicy();
+        DiscountPolicy amountPolicy = new AmountBasedDiscountPolicy();
+        Order orderWorth501Dollars = orderWorthNDollars(501);
+
+        // when
+        double flatDiscount = flatPolicy.discount(orderWorth501Dollars);
+        double amountDiscount = amountPolicy.discount(orderWorth501Dollars);
+
+        // then
+        assertThat(flatDiscount).isEqualTo(0.01);
+        assertThat(amountDiscount).isEqualTo(0.1);
+    }
+
+    private Order orderWorthNDollars(int totalCost) {
+        return new Order(OrderFixtureUtils.orderLineItemsWorthNDollars(totalCost));
+    }
+}

guava-collections-set/README.md

@@ -1,4 +1,8 @@
+# Guava
 
-### Relevant Articles: 
+## Relevant Articles:
 
+- [Guava – Sets](http://www.baeldung.com/guava-sets)
+- [Guide to Guava RangeSet](http://www.baeldung.com/guava-rangeset)
+- [Guava Set + Function = Map](http://www.baeldung.com/guava-set-function-map-tutorial)
 - [Guide to Guava Multiset](https://www.baeldung.com/guava-multiset)

guava-collections-set/src/test/java/org/baeldung/guava/GuavaMapFromSet.java

@@ -1,14 +1,9 @@
 package org.baeldung.guava;
 
-import java.util.AbstractMap;
-import java.util.AbstractSet;
-import java.util.Iterator;
-import java.util.Map;
-import java.util.Set;
-import java.util.WeakHashMap;
-
 import com.google.common.base.Function;
 
+import java.util.*;
+
 public class GuavaMapFromSet<K, V> extends AbstractMap<K, V> {
 
     private class SingleEntry implements Entry<K, V> {

guava-collections-set/src/test/java/org/baeldung/guava/GuavaMapFromSetUnitTest.java

@@ -1,15 +1,14 @@
 package org.baeldung.guava;
 
-import static org.junit.Assert.assertTrue;
+import com.google.common.base.Function;
+import org.junit.Test;
 
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
 
-import org.junit.Test;
-
-import com.google.common.base.Function;
+import static org.junit.Assert.assertTrue;
 
 public class GuavaMapFromSetUnitTest {
 

guava-collections-set/src/test/java/org/baeldung/guava/GuavaRangeSetUnitTest.java

@@ -1,13 +1,12 @@
 package org.baeldung.guava;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.assertFalse;
-import org.junit.Test;
 import com.google.common.collect.ImmutableRangeSet;
 import com.google.common.collect.Range;
 import com.google.common.collect.RangeSet;
 import com.google.common.collect.TreeRangeSet;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
 
 public class GuavaRangeSetUnitTest {
 
@@ -122,6 +121,5 @@ public class GuavaRangeSetUnitTest {
 	    .add(Range.closed(0, 2))
 	    .add(Range.closed(3, 5))
 	    .add(Range.closed(5, 8)).build();
-
     }
 }

guava-collections-set/src/test/java/org/baeldung/guava/GuavaSetOperationsUnitTest.java

@@ -0,0 +1,131 @@
+package org.baeldung.guava;
+
+import com.google.common.base.Function;
+import com.google.common.base.Joiner;
+import com.google.common.collect.*;
+import org.junit.Test;
+
+import java.util.List;
+import java.util.Set;
+
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+public class GuavaSetOperationsUnitTest {
+
+    @Test
+    public void whenCalculatingUnionOfSets_thenCorrect() {
+        final Set<Character> first = ImmutableSet.of('a', 'b', 'c');
+        final Set<Character> second = ImmutableSet.of('b', 'c', 'd');
+
+        final Set<Character> union = Sets.union(first, second);
+        assertThat(union, containsInAnyOrder('a', 'b', 'c', 'd'));
+    }
+
+    @Test
+    public void whenCalculatingCartesianProductOfSets_thenCorrect() {
+        final Set<Character> first = ImmutableSet.of('a', 'b');
+        final Set<Character> second = ImmutableSet.of('c', 'd');
+        final Set<List<Character>> result = Sets.cartesianProduct(ImmutableList.of(first, second));
+
+        final Function<List<Character>, String> func = new Function<List<Character>, String>() {
+            @Override
+            public final String apply(final List<Character> input) {
+                return Joiner
+                  .on(" ").join(input);
+            }
+        };
+
+        final Iterable<String> joined = Iterables.transform(result, func);
+        assertThat(joined, containsInAnyOrder("a c", "a d", "b c", "b d"));
+    }
+
+    @Test
+    public void whenCalculatingSetIntersection_thenCorrect() {
+        final Set<Character> first = ImmutableSet.of('a', 'b', 'c');
+        final Set<Character> second = ImmutableSet.of('b', 'c', 'd');
+
+        final Set<Character> intersection = Sets.intersection(first, second);
+        assertThat(intersection, containsInAnyOrder('b', 'c'));
+    }
+
+    @Test
+    public void whenCalculatingSetSymmetricDifference_thenCorrect() {
+        final Set<Character> first = ImmutableSet.of('a', 'b', 'c');
+        final Set<Character> second = ImmutableSet.of('b', 'c', 'd');
+
+        final Set<Character> intersection = Sets.symmetricDifference(first, second);
+        assertThat(intersection, containsInAnyOrder('a', 'd'));
+    }
+
+    @Test
+    public void whenCalculatingPowerSet_thenCorrect() {
+        final Set<Character> chars = ImmutableSet.of('a', 'b');
+        final Set<Set<Character>> result = Sets.powerSet(chars);
+
+        final Set<Character> empty = ImmutableSet.<Character> builder().build();
+        final Set<Character> a = ImmutableSet.of('a');
+        final Set<Character> b = ImmutableSet.of('b');
+        final Set<Character> aB = ImmutableSet.of('a', 'b');
+
+        assertThat(result, contains(empty, a, b, aB));
+    }
+
+    @Test
+    public void whenCreatingRangeOfIntegersSet_thenCreated() {
+        final int start = 10;
+        final int end = 30;
+        final ContiguousSet<Integer> set = ContiguousSet.create(Range.closed(start, end), DiscreteDomain.integers());
+
+        assertEquals(21, set.size());
+        assertEquals(10, set.first().intValue());
+        assertEquals(30, set.last().intValue());
+    }
+
+    @Test
+    public void whenUsingRangeSet_thenCorrect() {
+        final RangeSet<Integer> rangeSet = TreeRangeSet.create();
+        rangeSet.add(Range.closed(1, 10));
+        rangeSet.add(Range.closed(12, 15));
+
+        assertEquals(2, rangeSet.asRanges().size());
+
+        rangeSet.add(Range.closed(10, 12));
+        assertTrue(rangeSet.encloses(Range.closed(1, 15)));
+        assertEquals(1, rangeSet.asRanges().size());
+    }
+
+    @Test
+    public void whenInsertDuplicatesInMultiSet_thenInserted() {
+        final Multiset<String> names = HashMultiset.create();
+        names.add("John");
+        names.add("Adam", 3);
+        names.add("John");
+
+        assertEquals(2, names.count("John"));
+        names.remove("John");
+        assertEquals(1, names.count("John"));
+
+        assertEquals(3, names.count("Adam"));
+        names.remove("Adam", 2);
+        assertEquals(1, names.count("Adam"));
+    }
+
+    @Test
+    public void whenGetTopOcurringElementsWithMultiSet_thenCorrect() {
+        final Multiset<String> names = HashMultiset.create();
+        names.add("John");
+        names.add("Adam", 5);
+        names.add("Jane");
+        names.add("Tom", 2);
+
+        final Set<String> sorted = Multisets.copyHighestCountFirst(names).elementSet();
+        final List<String> topTwo = Lists.newArrayList(sorted).subList(0, 2);
+        assertEquals(2, topTwo.size());
+        assertEquals("Adam", topTwo.get(0));
+        assertEquals("Tom", topTwo.get(1));
+    }
+}

guava-collections/README.md

@@ -11,13 +11,10 @@
 - [Filtering and Transforming Collections in Guava](http://www.baeldung.com/guava-filter-and-transform-a-collection)
 - [Guava – Join and Split Collections](http://www.baeldung.com/guava-joiner-and-splitter-tutorial)
 - [Guava – Lists](http://www.baeldung.com/guava-lists)
-- [Guava – Sets](http://www.baeldung.com/guava-sets)
 - [Guava – Maps](http://www.baeldung.com/guava-maps)
 - [Guide to Guava Multimap](http://www.baeldung.com/guava-multimap)
-- [Guide to Guava RangeSet](http://www.baeldung.com/guava-rangeset)
 - [Guide to Guava RangeMap](http://www.baeldung.com/guava-rangemap)
 - [Guide to Guava MinMaxPriorityQueue and EvictingQueue](http://www.baeldung.com/guava-minmax-priority-queue-and-evicting-queue)
 - [Initialize a HashMap in Java](https://www.baeldung.com/java-initialize-hashmap)
-- [Guava Set + Function = Map](http://www.baeldung.com/guava-set-function-map-tutorial)
 - [Guide to Guava Table](http://www.baeldung.com/guava-table)
 - [Guide to Guava ClassToInstanceMap](http://www.baeldung.com/guava-class-to-instance-map)

guava-collections/src/test/java/org/baeldung/guava/GuavaCollectionTypesUnitTest.java

@@ -111,120 +111,6 @@ public class GuavaCollectionTypesUnitTest {
         assertThat(immutable, contains("John", "Adam", "Jane", "Tom"));
     }
 
-    // sets
-
-    @Test
-    public void whenCalculateUnionOfSets_thenCorrect() {
-        final Set<Character> first = ImmutableSet.of('a', 'b', 'c');
-        final Set<Character> second = ImmutableSet.of('b', 'c', 'd');
-
-        final Set<Character> union = Sets.union(first, second);
-        assertThat(union, containsInAnyOrder('a', 'b', 'c', 'd'));
-    }
-
-    @Test
-    public void whenCalculateSetsProduct_thenCorrect() {
-        final Set<Character> first = ImmutableSet.of('a', 'b');
-        final Set<Character> second = ImmutableSet.of('c', 'd');
-        final Set<List<Character>> result = Sets.cartesianProduct(ImmutableList.of(first, second));
-
-        final Function<List<Character>, String> func = new Function<List<Character>, String>() {
-            @Override
-            public final String apply(final List<Character> input) {
-                return Joiner.on(" ").join(input);
-            }
-        };
-
-        final Iterable<String> joined = Iterables.transform(result, func);
-        assertThat(joined, containsInAnyOrder("a c", "a d", "b c", "b d"));
-    }
-
-    @Test
-    public void whenCalculatingSetIntersection_thenCorrect() {
-        final Set<Character> first = ImmutableSet.of('a', 'b', 'c');
-        final Set<Character> second = ImmutableSet.of('b', 'c', 'd');
-
-        final Set<Character> intersection = Sets.intersection(first, second);
-        assertThat(intersection, containsInAnyOrder('b', 'c'));
-    }
-
-    @Test
-    public void whenCalculatingSetSymmetricDifference_thenCorrect() {
-        final Set<Character> first = ImmutableSet.of('a', 'b', 'c');
-        final Set<Character> second = ImmutableSet.of('b', 'c', 'd');
-
-        final Set<Character> intersection = Sets.symmetricDifference(first, second);
-        assertThat(intersection, containsInAnyOrder('a', 'd'));
-    }
-
-    @Test
-    public void whenCalculatingPowerSet_thenCorrect() {
-        final Set<Character> chars = ImmutableSet.of('a', 'b');
-        final Set<Set<Character>> result = Sets.powerSet(chars);
-
-        final Set<Character> empty = ImmutableSet.<Character> builder().build();
-        final Set<Character> a = ImmutableSet.of('a');
-        final Set<Character> b = ImmutableSet.of('b');
-        final Set<Character> aB = ImmutableSet.of('a', 'b');
-
-        assertThat(result, contains(empty, a, b, aB));
-    }
-
-    @Test
-    public void whenCreateRangeOfIntegersSet_thenCreated() {
-        final int start = 10;
-        final int end = 30;
-        final ContiguousSet<Integer> set = ContiguousSet.create(Range.closed(start, end), DiscreteDomain.integers());
-
-        assertEquals(21, set.size());
-        assertEquals(10, set.first().intValue());
-        assertEquals(30, set.last().intValue());
-    }
-
-    @Test
-    public void whenCreateRangeSet_thenCreated() {
-        final RangeSet<Integer> rangeSet = TreeRangeSet.create();
-        rangeSet.add(Range.closed(1, 10));
-        rangeSet.add(Range.closed(12, 15));
-
-        assertEquals(2, rangeSet.asRanges().size());
-
-        rangeSet.add(Range.closed(10, 12));
-        assertTrue(rangeSet.encloses(Range.closed(1, 15)));
-        assertEquals(1, rangeSet.asRanges().size());
-    }
-
-    @Test
-    public void whenInsertDuplicatesInMultiSet_thenInserted() {
-        final Multiset<String> names = HashMultiset.create();
-        names.add("John");
-        names.add("Adam", 3);
-        names.add("John");
-
-        assertEquals(2, names.count("John"));
-        names.remove("John");
-        assertEquals(1, names.count("John"));
-
-        assertEquals(3, names.count("Adam"));
-        names.remove("Adam", 2);
-        assertEquals(1, names.count("Adam"));
-    }
-
-    @Test
-    public void whenGetTopUsingMultiSet_thenCorrect() {
-        final Multiset<String> names = HashMultiset.create();
-        names.add("John");
-        names.add("Adam", 5);
-        names.add("Jane");
-        names.add("Tom", 2);
-
-        final Set<String> sorted = Multisets.copyHighestCountFirst(names).elementSet();
-        final List<String> topTwo = Lists.newArrayList(sorted).subList(0, 2);
-        assertEquals(2, topTwo.size());
-        assertEquals("Adam", topTwo.get(0));
-        assertEquals("Tom", topTwo.get(1));
-    }
-
     @Test
     public void whenCreateImmutableMap_thenCreated() {
         final Map<String, Integer> salary = ImmutableMap.<String, Integer> builder().put("John", 1000).put("Jane", 1500).put("Adam", 2000).put("Tom", 2000).build();

java-dates-2/README.md

@@ -1,2 +1,3 @@
 ## Relevant Articles:
 - [Converting Between LocalDate and XMLGregorianCalendar](https://www.baeldung.com/java-localdate-to-xmlgregoriancalendar)
+- [Convert Time to Milliseconds in Java](https://www.baeldung.com/java-time-milliseconds)

java-strings-2/README.MD

@@ -0,0 +1,5 @@
+## Relevant Articles
+
+- [Java Localization – Formatting Messages](https://www.baeldung.com/java-localization-messages-formatting)
+- [Check If a String Contains a Substring](https://www.baeldung.com/java-string-contains-substring)
+- [Removing Stopwords from a String in Java](https://www.baeldung.com/java-string-remove-stopwords)

java-strings-2/pom.xml

@@ -15,28 +15,6 @@
     </parent>
 
     <dependencies>
-        <dependency>
-            <groupId>commons-io</groupId>
-            <artifactId>commons-io</artifactId>
-            <version>${commons-io.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>log4j</groupId>
-            <artifactId>log4j</artifactId>
-            <version>${log4j.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>commons-codec</groupId>
-            <artifactId>commons-codec</artifactId>
-            <version>${commons-codec.version}</version>
-        </dependency>
-        <!-- test scoped -->
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.openjdk.jmh</groupId>
             <artifactId>jmh-core</artifactId>
@@ -57,11 +35,6 @@
             <artifactId>guava</artifactId>
             <version>${guava.version}</version>
         </dependency>
-        <dependency>
-            <groupId>com.vdurmont</groupId>
-            <artifactId>emoji-java</artifactId>
-            <version>${emoji-java.version}</version>
-        </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
@@ -73,38 +46,18 @@
             <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter-api</artifactId>
-            <version>${junit-jupiter-api.version}</version>
-            <scope>test</scope>
-        </dependency>
-
         <dependency>
             <groupId>org.hamcrest</groupId>
             <artifactId>hamcrest-library</artifactId>
             <version>${org.hamcrest.version}</version>
             <scope>test</scope>
         </dependency>
-
-        <!-- Added for password generation -->
-        <dependency>
-            <groupId>org.passay</groupId>
-            <artifactId>passay</artifactId>
-            <version>${passay.version}</version>
-        </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-text</artifactId>
             <version>${commons-text.version}</version>
         </dependency>
 
-        <dependency>
-            <groupId>org.ahocorasick</groupId>
-            <artifactId>ahocorasick</artifactId>
-            <version>${ahocorasick.version}</version>
-        </dependency>
-
     </dependencies>
 
     <build>
@@ -131,18 +84,10 @@
     </build>
 
     <properties>
-        <!-- util -->
         <commons-lang3.version>3.8.1</commons-lang3.version>
-        <commons-codec.version>1.10</commons-codec.version>
-        <!-- testing -->
-        <assertj.version>3.6.1</assertj.version>
         <icu4j.version>61.1</icu4j.version>
         <guava.version>27.0.1-jre</guava.version>
-        <emoji-java.version>4.0.0</emoji-java.version>
-        <junit-jupiter-api.version>5.3.1</junit-jupiter-api.version>
-        <passay.version>1.3.1</passay.version>
         <commons-text.version>1.4</commons-text.version>
-        <ahocorasick.version>0.4.0</ahocorasick.version>
     </properties>
 
 </project>

java-strings-2/src/main/java/com/baeldung/string/performance/RemovingStopwordsPerformanceComparison.java

@@ -0,0 +1,73 @@
+package com.baeldung.string.performance;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+
+
+@Fork(value = 3, warmups = 1)
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+public class RemovingStopwordsPerformanceComparison {
+
+    private String data;
+    
+    private List<String> stopwords;
+
+    private String stopwordsRegex;
+    
+    
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+
+    @Setup
+    public void setup() throws IOException {
+        data = new String(Files.readAllBytes(Paths.get("src/main/resources/shakespeare-hamlet.txt")));
+        data = data.toLowerCase();
+        stopwords = Files.readAllLines(Paths.get("src/main/resources/english_stopwords.txt"));
+        stopwordsRegex = stopwords.stream().collect(Collectors.joining("|", "\\b(", ")\\b\\s?"));
+    }
+
+    @Benchmark
+    public String removeManually() {
+        String[] allWords = data.split(" ");
+        StringBuilder builder = new StringBuilder();
+        for(String word:allWords) {
+            if(! stopwords.contains(word)) {
+                builder.append(word);
+                builder.append(' ');
+            }
+        }
+        return builder.toString().trim();
+    }
+
+    @Benchmark
+    public String removeAll() {
+        ArrayList<String> allWords = Stream.of(data.split(" "))
+            .collect(Collectors.toCollection(ArrayList<String>::new));
+        allWords.removeAll(stopwords);
+        return allWords.stream().collect(Collectors.joining(" "));
+    }
+
+    @Benchmark
+    public String replaceRegex() {
+        return data.replaceAll(stopwordsRegex, "");
+    }
+
+}

java-strings-2/src/main/resources/english_stopwords.txt

@@ -0,0 +1,127 @@
+i
+me
+my
+myself
+we
+our
+ours
+ourselves
+you
+your
+yours
+yourself
+yourselves
+he
+him
+his
+himself
+she
+her
+hers
+herself
+it
+its
+itself
+they
+them
+their
+theirs
+themselves
+what
+which
+who
+whom
+this
+that
+these
+those
+am
+is
+are
+was
+were
+be
+been
+being
+have
+has
+had
+having
+do
+does
+did
+doing
+a
+an
+the
+and
+but
+if
+or
+because
+as
+until
+while
+of
+at
+by
+for
+with
+about
+against
+between
+into
+through
+during
+before
+after
+above
+below
+to
+from
+up
+down
+in
+out
+on
+off
+over
+under
+again
+further
+then
+once
+here
+there
+when
+where
+why
+how
+all
+any
+both
+each
+few
+more
+most
+other
+some
+such
+no
+nor
+not
+only
+own
+same
+so
+than
+too
+very
+s
+t
+can
+will
+just
+don
+should
+now

java-strings-2/src/test/java/com/baeldung/initialization/StringInitializationUnitTest.java

@@ -0,0 +1,58 @@
+package com.baeldung.initialization;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
+
+import org.junit.Test;
+
+public class StringInitializationUnitTest {
+
+    private String fieldString;
+
+    void printDeclaredOnlyString() {
+        String localVarString = null;
+
+        System.out.println(localVarString); // compilation error
+        System.out.println(fieldString);
+    }
+
+    @Test
+    public void givenDeclaredFeldStringAndNullString_thenCompareEquals() {
+        String localVarString = null;
+
+        assertEquals(fieldString, localVarString);
+    }
+
+    @Test
+    public void givenTwoStringsWithSameLiteral_thenCompareReferencesEquals() {
+        String literalOne = "Baeldung";
+        String literalTwo = "Baeldung";
+
+        assertTrue(literalOne == literalTwo);
+    }
+
+    @Test
+    public void givenTwoStringsUsingNew_thenCompareReferencesNotEquals() {
+        String newStringOne = new String("Baeldung");
+        String newStringTwo = new String("Baeldung");
+
+        assertFalse(newStringOne == newStringTwo);
+    }
+
+    @Test
+    public void givenEmptyLiteralStringsAndNewObject_thenCompareEquals() {
+        String emptyLiteral = "";
+        String emptyNewString = new String("");
+
+        assertEquals(emptyLiteral, emptyNewString);
+    }
+
+    @Test
+    public void givenEmptyStringObjects_thenCompareEquals() {
+        String emptyNewString = new String("");
+        String emptyNewStringTwo = new String();
+
+        assertEquals(emptyNewString, emptyNewStringTwo);
+    }
+}

java-strings-2/src/test/java/com/baeldung/string/RemoveStopwordsUnitTest.java

@@ -0,0 +1,60 @@
+package com.baeldung.string;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class RemoveStopwordsUnitTest {
+    final String original = "The quick brown fox jumps over the lazy dog";
+    final String target = "quick brown fox jumps lazy dog";
+    static List<String> stopwords;
+
+    @BeforeClass
+    public static void loadStopwords() throws IOException {
+        stopwords = Files.readAllLines(Paths.get("src/main/resources/english_stopwords.txt"));
+    }
+
+    @Test
+    public void whenRemoveStopwordsManually_thenSuccess() {
+        String[] allWords = original.toLowerCase()
+            .split(" ");
+        StringBuilder builder = new StringBuilder();
+        for (String word : allWords) {
+            if (!stopwords.contains(word)) {
+                builder.append(word);
+                builder.append(' ');
+            }
+        }
+
+        String result = builder.toString().trim();
+        assertEquals(result, target);
+    }
+
+    @Test
+    public void whenRemoveStopwordsUsingRemoveAll_thenSuccess() {
+        ArrayList<String> allWords = Stream.of(original.toLowerCase()
+            .split(" "))
+            .collect(Collectors.toCollection(ArrayList<String>::new));
+        allWords.removeAll(stopwords);
+        String result = allWords.stream().collect(Collectors.joining(" "));
+        assertEquals(result, target);
+    }
+
+    @Test
+    public void whenRemoveStopwordsUsingRegex_thenSuccess() {
+        String stopwordsRegex = stopwords.stream()
+            .collect(Collectors.joining("|", "\\b(", ")\\b\\s?"));
+        String result = original.toLowerCase().replaceAll(stopwordsRegex, "");
+        assertEquals(result, target);
+    }
+
+}