Merge branch 'master' into BAEL-1423-jctools

.gitignore

@@ -34,8 +34,6 @@ spring-security-openid/src/main/resources/application.properties
 
 spring-all/*.log
 
-*.jar
-
 SpringDataInjectionDemo/.mvn/wrapper/maven-wrapper.properties
 
 spring-call-getters-using-reflection/.mvn/wrapper/maven-wrapper.properties

activejdbc/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [Introduction to ActiveJDBC](http://www.baeldung.com/active-jdbc)

activejdbc/pom.xml

@@ -12,6 +12,11 @@
         <activejdbc.version>1.4.13</activejdbc.version>
         <environments>development.test,development</environments>
     </properties>
+	<parent>
+        <artifactId>parent-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
     <build>
         <plugins>
             <plugin>

algorithms/README.md

@@ -17,3 +17,6 @@
 - [How to Calculate Levenshtein Distance in Java?](http://www.baeldung.com/java-levenshtein-distance)
 - [How to Find the Kth Largest Element in Java](http://www.baeldung.com/java-kth-largest-element)
 - [Multi-Swarm Optimization Algorithm in Java](http://www.baeldung.com/java-multi-swarm-algorithm)
+- [A Maze Solver in Java](http://www.baeldung.com/java-solve-maze)
+- [Create a Sudoku Solver in Java](http://www.baeldung.com/java-sudoku)
+- [Displaying Money Amounts in Words](http://www.baeldung.com/java-money-into-words)

animal-sniffer-mvn-plugin/pom.xml

@@ -11,7 +11,11 @@
   <properties>
         <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>	
     </properties>
-	
+	<parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
   <dependencies>
     <dependency>
       <groupId>junit</groupId>

apache-cayenne/src/test/java/com/baeldung/apachecayenne/CayenneAdvancedOperationIntegrationTest.java

@@ -19,7 +19,7 @@ import java.util.List;
 import static junit.framework.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
-public class CayenneAdvancedOperationTests {
+public class CayenneAdvancedOperationIntegrationTest {
     private static ObjectContext context = null;
 
     @BeforeClass

apache-cayenne/src/test/java/com/baeldung/apachecayenne/CayenneOperationIntegrationTest.java

@@ -16,7 +16,7 @@ import static junit.framework.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 
 
-public class CayenneOperationTests {
+public class CayenneOperationIntegrationTest {
     private static ObjectContext context = null;
 
     @BeforeClass

apache-curator/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Introduction to Apache Curator](http://www.baeldung.com/apache-curator)

apache-opennlp/pom.xml

@@ -0,0 +1,32 @@
+<?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>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+    <artifactId>apache-opennlp</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.opennlp</groupId>
+            <artifactId>opennlp-tools</artifactId>
+            <version>1.8.4</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.9.0</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/ChunkerTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.FileInputStream;
+import java.io.InputStream;
+import opennlp.tools.chunker.ChunkerME;
+import opennlp.tools.chunker.ChunkerModel;
+import opennlp.tools.postag.POSModel;
+import opennlp.tools.postag.POSTaggerME;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class ChunkerTest {
+
+    @Test
+    public void givenChunkerModel_whenChunk_thenChunksAreDetected() throws Exception {
+
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("He reckons the current account deficit will narrow to only 8 billion.");
+
+        InputStream inputStreamPOSTagger = getClass().getResourceAsStream("/models/en-pos-maxent.bin");
+        POSModel posModel = new POSModel(inputStreamPOSTagger);
+        POSTaggerME posTagger = new POSTaggerME(posModel);
+        String tags[] = posTagger.tag(tokens);
+
+        InputStream inputStreamChunker = new FileInputStream("src/main/resources/models/en-chunker.bin");
+        ChunkerModel chunkerModel = new ChunkerModel(inputStreamChunker);
+        ChunkerME chunker = new ChunkerME(chunkerModel);
+        String[] chunks = chunker.chunk(tokens, tags);
+        assertThat(chunks).contains("B-NP", "B-VP", "B-NP", "I-NP", "I-NP", "I-NP", "B-VP", "I-VP", "B-PP", "B-NP", "I-NP", "I-NP", "O");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/LanguageDetectorAndTrainingDataTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.Arrays;
+import opennlp.tools.langdetect.Language;
+import opennlp.tools.langdetect.LanguageDetector;
+import opennlp.tools.langdetect.LanguageDetectorFactory;
+import opennlp.tools.langdetect.LanguageDetectorME;
+import opennlp.tools.langdetect.LanguageDetectorModel;
+import opennlp.tools.langdetect.LanguageDetectorSampleStream;
+import opennlp.tools.util.InputStreamFactory;
+import opennlp.tools.util.MarkableFileInputStreamFactory;
+import opennlp.tools.util.ObjectStream;
+import opennlp.tools.util.PlainTextByLineStream;
+import opennlp.tools.util.TrainingParameters;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.tuple;
+import org.junit.Test;
+
+public class LanguageDetectorAndTrainingDataTest {
+
+    @Test
+    public void givenLanguageDictionary_whenLanguageDetect_thenLanguageIsDetected() throws FileNotFoundException, IOException {
+        InputStreamFactory dataIn = new MarkableFileInputStreamFactory(new File("src/main/resources/models/DoccatSample.txt"));
+        ObjectStream lineStream = new PlainTextByLineStream(dataIn, "UTF-8");
+        LanguageDetectorSampleStream sampleStream = new LanguageDetectorSampleStream(lineStream);
+        TrainingParameters params = new TrainingParameters();
+        params.put(TrainingParameters.ITERATIONS_PARAM, 100);
+        params.put(TrainingParameters.CUTOFF_PARAM, 5);
+        params.put("DataIndexer", "TwoPass");
+        params.put(TrainingParameters.ALGORITHM_PARAM, "NAIVEBAYES");
+
+        LanguageDetectorModel model = LanguageDetectorME.train(sampleStream, params, new LanguageDetectorFactory());
+
+        LanguageDetector ld = new LanguageDetectorME(model);
+        Language[] languages = ld.predictLanguages("estava em uma marcenaria na Rua Bruno");
+        
+        assertThat(Arrays.asList(languages)).extracting("lang", "confidence").contains(tuple("pob", 0.9999999950605625),
+                 tuple("ita", 4.939427661577956E-9), tuple("spa", 9.665954064665144E-15),
+                tuple("fra", 8.250349924885834E-25));
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/LemmetizerTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.lemmatizer.DictionaryLemmatizer;
+import opennlp.tools.postag.POSModel;
+import opennlp.tools.postag.POSTaggerME;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class LemmetizerTest {
+
+    @Test
+    public void givenEnglishDictionary_whenLemmatize_thenLemmasAreDetected() throws Exception {
+
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("John has a sister named Penny.");
+
+        InputStream inputStreamPOSTagger = getClass().getResourceAsStream("/models/en-pos-maxent.bin");
+        POSModel posModel = new POSModel(inputStreamPOSTagger);
+        POSTaggerME posTagger = new POSTaggerME(posModel);
+        String tags[] = posTagger.tag(tokens);
+        InputStream dictLemmatizer = getClass().getResourceAsStream("/models/en-lemmatizer.dict");
+        DictionaryLemmatizer lemmatizer = new DictionaryLemmatizer(dictLemmatizer);
+        String[] lemmas = lemmatizer.lemmatize(tokens, tags);
+
+        assertThat(lemmas).contains("O", "have", "a", "sister", "name", "O", "O");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/NamedEntityRecognitionTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import opennlp.tools.namefind.NameFinderME;
+import opennlp.tools.namefind.TokenNameFinderModel;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import opennlp.tools.util.Span;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class NamedEntityRecognitionTest {
+
+    @Test
+    public void givenEnglishPersonModel_whenNER_thenPersonsAreDetected() throws Exception {
+        
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("John is 26 years old. His best friend's name is Leonard. He has a sister named Penny.");
+        
+        InputStream inputStreamNameFinder = getClass().getResourceAsStream("/models/en-ner-person.bin");
+        TokenNameFinderModel model = new TokenNameFinderModel(inputStreamNameFinder);
+        NameFinderME nameFinderME = new NameFinderME(model);
+        List<Span> spans = Arrays.asList(nameFinderME.find(tokens));
+        assertThat(spans.toString()).isEqualTo("[[0..1) person, [13..14) person, [20..21) person]");
+        List<String> names = new ArrayList<String>();
+        int k = 0;
+        for (Span s : spans) {
+            names.add("");
+            for (int index = s.getStart(); index < s.getEnd(); index++) {
+                names.set(k, names.get(k) + tokens[index]);
+            }
+            k++;
+        }
+        assertThat(names).contains("John","Leonard","Penny");
+    }
+
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/POSTaggerTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.postag.POSModel;
+import opennlp.tools.postag.POSTaggerME;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class POSTaggerTest {
+
+    @Test
+    public void givenPOSModel_whenPOSTagging_thenPOSAreDetected() throws Exception {
+
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("John has a sister named Penny.");
+
+        InputStream inputStreamPOSTagger = getClass().getResourceAsStream("/models/en-pos-maxent.bin");
+        POSModel posModel = new POSModel(inputStreamPOSTagger);
+        POSTaggerME posTagger = new POSTaggerME(posModel);
+        String tags[] = posTagger.tag(tokens);
+        assertThat(tags).contains("NNP", "VBZ", "DT", "NN", "VBN", "NNP", ".");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/SentenceDetectionTest.java

@@ -0,0 +1,28 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.sentdetect.SentenceDetectorME;
+import opennlp.tools.sentdetect.SentenceModel;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class SentenceDetectionTest {
+
+    @Test
+    public void givenEnglishModel_whenDetect_thenSentencesAreDetected() throws Exception {
+
+        String paragraph = "This is a statement. This is another statement. Now is an abstract word for time, "
+                + "that is always flying. And my email address is google@gmail.com.";
+
+        InputStream is = getClass().getResourceAsStream("/models/en-sent.bin");
+        SentenceModel model = new SentenceModel(is);
+
+        SentenceDetectorME sdetector = new SentenceDetectorME(model);
+
+        String sentences[] = sdetector.sentDetect(paragraph);
+        assertThat(sentences).contains("This is a statement.",
+                "This is another statement.",
+                "Now is an abstract word for time, that is always flying.",
+                "And my email address is google@gmail.com.");
+    }
+}

apache-opennlp/src/test/java/com/baeldung/apache/opennlp/TokenizerTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.apache.opennlp;
+
+import java.io.InputStream;
+import opennlp.tools.tokenize.SimpleTokenizer;
+import opennlp.tools.tokenize.TokenizerME;
+import opennlp.tools.tokenize.TokenizerModel;
+import opennlp.tools.tokenize.WhitespaceTokenizer;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class TokenizerTest {
+
+    @Test
+    public void givenEnglishModel_whenTokenize_thenTokensAreDetected() throws Exception {
+        InputStream inputStream = getClass().getResourceAsStream("/models/en-token.bin");
+        TokenizerModel model = new TokenizerModel(inputStream);
+        TokenizerME tokenizer = new TokenizerME(model);
+        String[] tokens = tokenizer.tokenize("Baeldung is a Spring Resource.");
+        assertThat(tokens).contains("Baeldung", "is", "a", "Spring", "Resource", ".");
+    }
+    
+    @Test
+    public void givenWhitespaceTokenizer_whenTokenize_thenTokensAreDetected() throws Exception {
+        WhitespaceTokenizer tokenizer = WhitespaceTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("Baeldung is a Spring Resource.");
+        assertThat(tokens).contains("Baeldung", "is", "a", "Spring", "Resource.");
+    }
+    
+    @Test
+    public void givenSimpleTokenizer_whenTokenize_thenTokensAreDetected() throws Exception {
+        SimpleTokenizer tokenizer = SimpleTokenizer.INSTANCE;
+        String[] tokens = tokenizer.tokenize("Baeldung is a Spring Resource.");
+        assertThat(tokens).contains("Baeldung", "is", "a", "Spring", "Resource", ".");
+    }
+
+}

apache-spark/pom.xml

@@ -13,7 +13,11 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 	</properties>
-
+	<parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
 	<dependencies>
 		<!-- https://mvnrepository.com/artifact/org.apache.spark/spark-core_2.10 -->
 		<dependency>

apache-tika/README.md

@@ -0,0 +1,3 @@
+## Relevant articles:
+
+- [Content Analysis with Apache Tika](http://www.baeldung.com/apache-tika)

apache-zookeeper/README.md

@@ -0,0 +1,3 @@
+## Relevant articles:
+
+- [Getting Started with Java and Zookeeper](http://www.baeldung.com/java-zookeeper)

asm/pom.xml

@@ -1,10 +1,16 @@
 <?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">
+<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.examples</groupId>
     <artifactId>asm</artifactId>
     <version>1.0</version>
     <packaging>jar</packaging>
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
     <dependencies>
         <dependency>
             <groupId>org.ow2.asm</groupId>
@@ -17,11 +23,13 @@
             <version>5.2</version>
         </dependency>
     </dependencies>
+    
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
     </properties>
+    
     <build>
         <plugins>
             <plugin>

aws/README.md

@@ -4,4 +4,5 @@
 - [AWS S3 with Java](http://www.baeldung.com/aws-s3-java)
 - [AWS Lambda With Java](http://www.baeldung.com/java-aws-lambda)
 - [Managing EC2 Instances in Java](http://www.baeldung.com/ec2-java)
+- [http://www.baeldung.com/aws-s3-multipart-upload](https://github.com/eugenp/tutorials/tree/master/aws)
 

aws/pom.xml

@@ -24,6 +24,8 @@
         <assertj-core.version>3.8.0</assertj-core.version>
         <dynamodblocal.version>1.11.86</dynamodblocal.version>
         <dynamodblocal.repository.url>https://s3-us-west-2.amazonaws.com/dynamodb-local/release</dynamodblocal.repository.url>
+        <commons-codec-version>1.10.L001</commons-codec-version>
+        <jets3t-version>0.9.4.0006L</jets3t-version>
     </properties>
 
     <dependencies>
@@ -97,6 +99,19 @@
             <version>${dynamodblocal.version}</version>
             <scope>test</scope>
         </dependency>
+
+        <!-- JetS3t -->
+        <dependency>
+            <groupId>org.lucee</groupId>
+            <artifactId>jets3t</artifactId>
+            <version>${jets3t-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.lucee</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec-version}</version>
+        </dependency>
+
     </dependencies>
 
     <build>

aws/src/test/java/com/baeldung/dynamodb/ProductInfoRepositoryIntegrationTest.java

@@ -17,7 +17,6 @@ import org.junit.Test;
 
 import java.io.IOException;
 import java.io.InputStream;
-import java.net.URISyntaxException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;

aws/src/test/java/com/baeldung/jets3t/JetS3tLiveTest.java

@@ -0,0 +1,351 @@
+package com.baeldung.jets3t;
+
+import org.apache.commons.codec.digest.DigestUtils;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.jets3t.service.S3Service;
+import org.jets3t.service.ServiceException;
+import org.jets3t.service.impl.rest.httpclient.RestS3Service;
+import org.jets3t.service.model.S3Bucket;
+import org.jets3t.service.model.S3Object;
+import org.jets3t.service.model.StorageObject;
+import org.jets3t.service.security.AWSCredentials;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.*;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
+import static junit.framework.TestCase.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public class JetS3tLiveTest {
+
+    private Log log = LogFactory.getLog(JetS3tLiveTest.class);
+
+    private static final String BucketName = "baeldung-barfoo";
+    private static final String TestString = "test string";
+    private static final String TestStringName = "string object";
+    private static final String TgtBucket = "baeldung-tgtbucket";
+
+    private static S3Service s3Service;
+
+    @BeforeClass
+    public static void connectS3() throws Exception {
+
+        // Replace with your keys
+        String awsAccessKey = "your access key";
+        String awsSecretKey = "your secret key";
+
+        // Create credentials
+        AWSCredentials awsCredentials = new AWSCredentials(awsAccessKey, awsSecretKey);
+
+        // Create service
+        s3Service = new RestS3Service(awsCredentials);
+    }
+
+    @Test
+    public void givenCreate_AndDeleteBucket_CountGoesUpThenDown() throws Exception {
+
+        // List buckets, get a count
+        S3Bucket[] myBuckets = s3Service.listAllBuckets();
+        int count = Arrays.stream(myBuckets).map(S3Bucket::getName).collect(Collectors.toList()).size();
+
+        // Create a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        // List again
+        myBuckets = s3Service.listAllBuckets();
+        int newCount = Arrays.stream(myBuckets).map(S3Bucket::getName).collect(Collectors.toList()).size();
+
+        // We should have one more
+        assertEquals((count + 1), newCount);
+
+        // Delete so next test doesn't fail
+        deleteBucket();
+
+        // Check the count again, just for laughs
+        myBuckets = s3Service.listAllBuckets();
+        newCount = Arrays.stream(myBuckets).map(S3Bucket::getName).collect(Collectors.toList()).size();
+        assertEquals(count, newCount);
+
+    }
+
+    private S3Bucket createBucket() throws Exception {
+        S3Bucket bucket = s3Service.createBucket(BucketName);
+        log.info(bucket);
+        return bucket;
+    }
+
+
+    private void deleteBucket() throws ServiceException {
+        s3Service.deleteBucket(BucketName);
+    }
+
+    @Test
+    public void givenString_Uploaded_StringInfoIsAvailable() throws Exception {
+
+        // Create a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        // Upload a string
+        uploadStringData();
+
+        // Get the details
+        StorageObject objectDetailsOnly = s3Service.getObjectDetails(BucketName, TestStringName);
+        log.info("Content type: " + objectDetailsOnly.getContentType() + " length: " + objectDetailsOnly.getContentLength());
+
+        // Delete it
+        deleteObject(TestStringName);
+
+        // For next test
+        deleteBucket();
+    }
+
+    private void uploadStringData() throws Exception {
+        S3Object stringObject = new S3Object(TestStringName, TestString);
+        s3Service.putObject(BucketName, stringObject);
+        log.info("Content type:" + stringObject.getContentType());
+    }
+
+    private void deleteObject(String objectName) throws ServiceException {
+        s3Service.deleteObject(BucketName, objectName);
+    }
+
+    @Test
+    public void givenStringUploaded_StringIsDownloaded() throws Exception {
+
+        // Get a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        uploadStringData();
+
+        // Download
+        S3Object stringObject = s3Service.getObject(BucketName, TestStringName);
+
+        // Process stream into a string
+        String downloadedString = new BufferedReader(new InputStreamReader(stringObject.getDataInputStream())).lines().collect(Collectors.joining("\n"));
+
+        // Verify
+        assertTrue(TestString.equals(downloadedString));
+
+
+        // Clean up for next test
+        deleteObject(TestStringName);
+        deleteBucket();
+    }
+
+    @Test
+    public void givenBinaryFileUploaded_FileIsDownloaded() throws Exception {
+
+        // get a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        // Put a binary file
+        S3Object fileObject = new S3Object(new File("src/test/resources/test.jpg"));
+        s3Service.putObject(BucketName, fileObject);
+
+        // Print info about type and name
+        log.info("Content type:" + fileObject.getContentType());
+        log.info("File object name is " + fileObject.getName());
+
+        // Download
+        S3Object newFileObject = s3Service.getObject(BucketName, "test.jpg");
+
+        // Save to a different name
+        File newFile = new File("src/test/resources/newtest.jpg");
+        Files.copy(newFileObject.getDataInputStream(), newFile.toPath(), REPLACE_EXISTING);
+
+
+        // Get hashes and compare
+        String origMD5 = getFileMD5("src/test/resources/test.jpg");
+        String newMD5 = getFileMD5("src/test/resources/newtest.jpg");
+        assertTrue(origMD5.equals(newMD5));
+
+        // Clean up
+        deleteObject("test.jpg");
+        deleteBucket();
+    }
+
+    // Get MD5 hash for a file
+    private String getFileMD5(String filename) throws IOException {
+        try (FileInputStream fis = new FileInputStream(new File(filename))) {
+            return DigestUtils.md5Hex(fis);
+        }
+    }
+
+
+
+    @Test
+    public void givenStreamDataUploaded_StreamDataIsDownloaded() throws Exception {
+
+        // get a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        ArrayList<Integer> numbers = new ArrayList<>();
+        numbers.add(2);
+        numbers.add(3);
+        numbers.add(5);
+        numbers.add(7);
+
+        // Serialize ArrayList
+        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+        ObjectOutputStream objectOutputStream = new ObjectOutputStream(bytes);
+        objectOutputStream.writeObject(numbers);
+
+        // Wrap bytes
+        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes.toByteArray());
+
+        // Create and populate object
+        S3Object streamObject = new S3Object("stream");
+        streamObject.setDataInputStream(byteArrayInputStream);
+        streamObject.setContentLength(byteArrayInputStream.available());
+        streamObject.setContentType("binary/octet-stream");
+
+        // Put it
+        s3Service.putObject(BucketName, streamObject);
+
+        // Get it
+        S3Object newStreamObject = s3Service.getObject(BucketName, "stream");
+
+        // Convert back to ArrayList
+        ObjectInputStream objectInputStream = new ObjectInputStream(newStreamObject.getDataInputStream());
+        ArrayList<Integer> newNumbers = (ArrayList<Integer>)objectInputStream.readObject();
+
+        assertEquals(2, (int)newNumbers.get(0));
+        assertEquals(3, (int)newNumbers.get(1));
+        assertEquals(5, (int)newNumbers.get(2));
+        assertEquals(7, (int)newNumbers.get(3));
+
+        // Clean up
+        deleteObject("stream");
+        deleteBucket();
+    }
+
+    @Test
+    public void whenFileCopied_CopyIsSame() throws Exception {
+
+        // get a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        // Put a binary file
+        S3Object fileObject = new S3Object(new File("src/test/resources/test.jpg"));
+        s3Service.putObject(BucketName, fileObject);
+
+
+        // Copy it
+        S3Object targetObject = new S3Object("testcopy.jpg");
+        s3Service.copyObject(BucketName, "test.jpg", BucketName, targetObject, false);
+
+
+        // Download
+        S3Object newFileObject = s3Service.getObject(BucketName, "testcopy.jpg");
+
+        // Save to a different name
+        File newFile = new File("src/test/resources/testcopy.jpg");
+        Files.copy(newFileObject.getDataInputStream(), newFile.toPath(), REPLACE_EXISTING);
+
+
+        // Get hashes and compare
+        String origMD5 = getFileMD5("src/test/resources/test.jpg");
+        String newMD5 = getFileMD5("src/test/resources/testcopy.jpg");
+        assertTrue(origMD5.equals(newMD5));
+
+        // Clean up
+        deleteObject("test.jpg");
+        deleteObject("testcopy.jpg");
+        deleteBucket();
+
+    }
+
+
+    @Test
+    public void whenFileRenamed_NewNameIsSame() throws Exception {
+
+        // get a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        // Put a binary file
+        S3Object fileObject = new S3Object(new File("src/test/resources/test.jpg"));
+        s3Service.putObject(BucketName, fileObject);
+
+
+        // Copy it
+        s3Service.renameObject(BucketName, "test.jpg", new S3Object("spidey.jpg"));
+
+
+        // Download
+        S3Object newFileObject = s3Service.getObject(BucketName, "spidey.jpg");
+
+        // Save to a different name
+        File newFile = new File("src/test/resources/spidey.jpg");
+        Files.copy(newFileObject.getDataInputStream(), newFile.toPath(), REPLACE_EXISTING);
+
+
+        // Get hashes and compare
+        String origMD5 = getFileMD5("src/test/resources/test.jpg");
+        String newMD5 = getFileMD5("src/test/resources/spidey.jpg");
+        assertTrue(origMD5.equals(newMD5));
+
+        // Clean up
+        deleteObject("test.jpg");
+        deleteObject("spidey.jpg");
+        deleteBucket();
+
+    }
+
+    @Test
+    public void whenFileMoved_NewInstanceIsSame() throws Exception {
+
+        // get a bucket
+        S3Bucket bucket = createBucket();
+        assertNotNull(bucket);
+
+        // create another bucket
+        S3Bucket tgtBucket = s3Service.createBucket(TgtBucket);
+
+
+        // Put a binary file
+        S3Object fileObject = new S3Object(new File("src/test/resources/test.jpg"));
+        s3Service.putObject(BucketName, fileObject);
+
+
+        // Copy it
+        s3Service.moveObject(BucketName, "test.jpg", TgtBucket,
+            new S3Object("spidey.jpg"), false);
+
+
+        // Download
+        S3Object newFileObject = s3Service.getObject(TgtBucket, "spidey.jpg");
+
+        // Save to a different name
+        File newFile = new File("src/test/resources/spidey.jpg");
+        Files.copy(newFileObject.getDataInputStream(), newFile.toPath(), REPLACE_EXISTING);
+
+
+        // Get hashes and compare
+        String origMD5 = getFileMD5("src/test/resources/test.jpg");
+        String newMD5 = getFileMD5("src/test/resources/spidey.jpg");
+        assertTrue(origMD5.equals(newMD5));
+
+        // Clean up
+        deleteBucket();
+
+        s3Service.deleteObject(TgtBucket, "spidey.jpg");
+        s3Service.deleteBucket(TgtBucket);
+    }
+
+
+}

aws/src/test/java/com/baeldung/s3/MultipartUploadLiveTest.java

@@ -20,7 +20,7 @@ import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
-public class MultipartUploadTest {
+public class MultipartUploadLiveTest {
 
     private static final String BUCKET_NAME = "bucket_name";
     private static final String KEY_NAME = "picture.jpg";

baeldung-pmd-rules.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+<ruleset name="Baeldung custom pmd rules" xmlns="http://pmd.sf.net/ruleset/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd" 
+	xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd">
+	<description>Baeldung custom PMD rules</description>
+	<rule name="UnitTestMustFollowNamingConventionRule" message="Test class name doesn't follow the naming convention" class="org.baeldung.pmd.UnitTestNamingConventionRule">
+		<description>Test does not follow Baeldung naming convention</description>
+		<priority>3</priority>
+	</rule>
+</ruleset>

bootique/pom.xml

@@ -13,9 +13,9 @@
 	</properties>
 
 	<parent>
-		<groupId>io.bootique.parent</groupId>
+        <groupId>com.baeldung</groupId>
-		<artifactId>bootique-parent</artifactId>
+        <artifactId>parent-modules</artifactId>
-		<version>0.12</version>
+        <version>1.0.0-SNAPSHOT</version>
     </parent>
 
 	<dependencyManagement>

camel-api/pom.xml

@@ -1,22 +1,17 @@
 <?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.example</groupId>
     <artifactId>spring-boot-camel</artifactId>
     <version>0.0.1-SNAPSHOT</version>
-
     <name>Spring-Boot - Camel API</name>
     
-	<properties>
+    <parent>
-		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <groupId>com.baeldung</groupId>
-		<maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
+        <artifactId>parent-modules</artifactId>
-		<maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
+        <version>1.0.0-SNAPSHOT</version>
-		<camel.version>2.19.1</camel.version>
+    </parent>
-	    <spring-boot-starter.version>1.5.4.RELEASE</spring-boot-starter.version>
-	</properties>
 
     <dependencies>
         <dependency>
@@ -58,11 +53,6 @@
                     <target>1.8</target>
                 </configuration>
             </plugin>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-surefire-plugin</artifactId>
-				<version>${maven-surefire-plugin.version}</version>
-			</plugin>
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
@@ -77,4 +67,13 @@
             </plugin>
         </plugins>
     </build>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
+        <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
+        <camel.version>2.19.1</camel.version>
+        <spring-boot-starter.version>1.5.4.RELEASE</spring-boot-starter.version>
+    </properties>
+
 </project>

cas/cas-server/pom.xml

@@ -7,7 +7,12 @@
     <artifactId>cas-server</artifactId>
     <packaging>war</packaging>
     <version>1.0</version>
-
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.0.0.M7</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
     <build>
         <plugins>
             <plugin>

checker-plugin/README.md

@@ -0,0 +1,3 @@
+### Relevant articles
+
+- [The Checker Framework – Pluggable Type Systems for Java](http://www.baeldung.com/checker-framework)

checker-plugin/pom.xml

@@ -7,6 +7,11 @@
     <version>1.0-SNAPSHOT</version>
     <name>checker-plugin</name>
     <url>http://maven.apache.org</url>
+	<parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
 
     <!-- https://checkerframework.org/manual/#maven -->
 

core-groovy/README.md

@@ -2,3 +2,5 @@
 
 ## Relevant articles:
 
+- [JDBC with Groovy](http://www.baeldung.com/jdbc-groovy)
+- [Working with JSON in Groovy](http://www.baeldung.com/groovy-json)

core-groovy/src/test/groovy/com/baeldung/json/JsonParserTest.groovy

@@ -24,7 +24,7 @@ class JsonParserTest extends Specification {
             account.value == 15.6
     }
 
-    def 'Should parse to Account given Json String with date property' () {
+    /*def 'Should parse to Account given Json String with date property' () {
         given:
             def json = '{"id":"1234","value":15.6,"createdAt":"2018-01-01T00:00:00+0000"}'
         when:
@@ -36,9 +36,9 @@ class JsonParserTest extends Specification {
             account.value == 15.6
             println account.createdAt
             account.createdAt == Date.parse('yyyy-MM-dd', '2018-01-01')
-    }
+    }*/
 
-    def 'Should parse to Json given an Account object' () {
+    /*def 'Should parse to Json given an Account object' () {
         given:
             Account account = new Account(
                     id: '123',
@@ -50,7 +50,7 @@ class JsonParserTest extends Specification {
         then:
             json
             json == '{"value":15.6,"createdAt":"2018-01-01T00:00:00+0000","id":"123"}'
-    }
+    }*/
 
     def 'Should prettify given a json string' () {
         given:

core-java-8/README.md

@@ -43,3 +43,4 @@
 - [Shuffling Collections In Java](http://www.baeldung.com/java-shuffle-collection)
 - [Java 8 StringJoiner](http://www.baeldung.com/java-string-joiner)
 - [Introduction to Spliterator in Java](http://www.baeldung.com/java-spliterator)
+- [Java 8 Math New Methods](http://www.baeldung.com/java-8-math)

core-java-8/pom.xml

@@ -8,7 +8,6 @@
 
     <name>core-java-8</name>
 
-
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>

core-java-8/src/main/java/com/baeldung/java_8_features/Car.java

@@ -0,0 +1,31 @@
+package com.baeldung.java_8_features;
+
+public class Car {
+
+    private String model;
+    private int topSpeed;
+
+    public Car(String model, int topSpeed) {
+        super();
+        this.model = model;
+        this.topSpeed = topSpeed;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    public void setModel(String model) {
+        this.model = model;
+    }
+
+    public int getTopSpeed() {
+        return topSpeed;
+    }
+
+    public void setTopSpeed(int topSpeed) {
+        this.topSpeed = topSpeed;
+    }
+
+
+}

core-java-8/src/test/java/com/baeldung/java8/Java8MaxMinUnitTest.java

@@ -1,6 +1,8 @@
 package com.baeldung.java8;
 
+import com.baeldung.java_8_features.Car;
 import com.baeldung.java_8_features.Person;
+
 import org.junit.Test;
 
 import java.util.Arrays;
@@ -44,4 +46,29 @@ public class Java8MaxMinUnitTest {
         assertEquals("Should be Alex", alex, minByAge);
     }
 
+    @Test
+    public void whenArrayIsOfIntegerThenMinUsesIntegerComparator() {
+        int[] integers = new int[] { 20, 98, 12, 7, 35 };
+
+        int min = Arrays.stream(integers)
+            .min()
+            .getAsInt();
+
+        assertEquals(7, min);
+    }
+
+    @Test
+    public void whenArrayIsOfCustomTypeThenMaxUsesCustomComparator() {
+        final Car porsche = new Car("Porsche 959", 319);
+        final Car ferrari = new Car("Ferrari 288 GTO", 303);
+        final Car bugatti = new Car("Bugatti Veyron 16.4 Super Sport", 415);
+        final Car mcLaren = new Car("McLaren F1", 355);
+        final Car[] fastCars = { porsche, ferrari, bugatti, mcLaren };
+
+        final Car maxBySpeed = Arrays.stream(fastCars)
+            .max(Comparator.comparing(Car::getTopSpeed))
+            .orElseThrow(NoSuchElementException::new);
+
+        assertEquals(bugatti, maxBySpeed);
+    }
 }

core-java-8/src/test/java/com/baeldung/time/ElapsedTimeUnitTest.java

@@ -0,0 +1,76 @@
+package com.baeldung.time;
+
+import static org.junit.Assert.assertEquals;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.commons.lang3.time.StopWatch;
+import org.junit.Test;
+
+public class ElapsedTimeUnitTest {
+
+    @Test
+    public void givenRunningTask_whenMeasuringTimeWithCurrentTimeMillis_thenGetElapsedTime() throws InterruptedException {
+        long start = System.currentTimeMillis();
+        
+        simulateRunningTask();
+        
+        long finish = System.currentTimeMillis();
+        
+        long timeElapsed = finish - start;
+        
+        assertEquals(true, (2000L <= timeElapsed) && (timeElapsed <= 3000L));
+    }
+    
+    @Test
+    public void giveRunningTask_whenMeasuringTimeWithNanoTime_thenGetElapsedTime() throws InterruptedException {
+        long start = System.nanoTime();
+        
+        simulateRunningTask();
+        
+        long finish = System.nanoTime();
+        
+        long timeElapsed = finish - start;
+        
+        assertEquals(true, (2000000000L <= timeElapsed) && (timeElapsed <= 3000000000L));
+    }
+    
+    @Test
+    public void givenRunningTask_whenMeasuringTimeWithStopWatch_thenGetElapsedTime() throws InterruptedException {
+        StopWatch watch = new StopWatch();        
+        watch.start();
+
+        simulateRunningTask();
+        
+        watch.stop();
+        
+        long timeElapsed = watch.getTime();
+        
+        assertEquals(true, (2000L <= timeElapsed) && (timeElapsed <= 3000L));
+    }
+    
+    @Test
+    public void givenRunningTask_whenMeasuringTimeWithInstantClass_thenGetElapsedTime() throws InterruptedException {
+        Instant start = Instant.now();
+        
+        simulateRunningTask();
+        
+        Instant finish = Instant.now();
+        
+        long timeElapsed = Duration.between(start, finish).toMillis();
+        
+        assertEquals(true, (2000L <= timeElapsed) && (timeElapsed <= 3000L));
+    }
+    
+    /**
+     * Simulate task running for 2.5 seconds.
+     * 
+     * @throws InterruptedException
+     */
+    private static void simulateRunningTask() throws InterruptedException {
+        TimeUnit.MILLISECONDS.sleep(2500); // 2.5 seconds
+
+    } 
+}

core-java-9/README.md

@@ -20,3 +20,5 @@
 - [Compact Strings in Java 9](http://www.baeldung.com/java-9-compact-string)
 - [Convert Date to LocalDate or LocalDateTime and Back](http://www.baeldung.com/java-date-to-localdate-and-localdatetime)
 - [Java 9 Variable Handles Demistyfied](http://www.baeldung.com/java-variable-handles)
+- [Exploring the New HTTP Client in Java 9](http://www.baeldung.com/java-9-http-client)
+- [Method Handles in Java](http://www.baeldung.com/java-method-handles)

core-java-9/compile-simple-modules.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+javac -d outDir --module-source-path src/simple-modules $(find src/simple-modules -name "*.java")

core-java-9/pom.xml

@@ -6,7 +6,11 @@
     <version>0.2-SNAPSHOT</version>
 
     <name>core-java-9</name>
-
+	<parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
     <pluginRepositories>
         <pluginRepository>
             <id>apache.snapshots</id>

core-java-9/run-simple-module-app.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+java --module-path outDir -m main.app/com.baeldung.modules.main.MainApp

core-java-9/src/simple-modules/hello.modules/com/baeldung/modules/hello/HelloInterface.java

@@ -0,0 +1,5 @@
+package com.baeldung.modules.hello;
+
+public interface HelloInterface {
+    public void sayHello();
+}

core-java-9/src/simple-modules/hello.modules/com/baeldung/modules/hello/HelloModules.java

@@ -0,0 +1,11 @@
+package com.baeldung.modules.hello;
+
+public class HelloModules implements HelloInterface {
+    public static void doSomething() {
+        System.out.println("Hello, Modules!");
+    }
+
+    public void sayHello() {
+        System.out.println("Hello!");
+    }
+}

core-java-9/src/simple-modules/hello.modules/module-info.java

@@ -0,0 +1,4 @@
+module hello.modules {
+    exports com.baeldung.modules.hello;
+    provides com.baeldung.modules.hello.HelloInterface with com.baeldung.modules.hello.HelloModules;
+}

core-java-9/src/simple-modules/main.app/com/baeldung/modules/main/MainApp.java

@@ -0,0 +1,12 @@
+package com.baeldung.modules.main;
+
+import com.baeldung.modules.hello.HelloModules;
+
+public class MainApp {
+    public static void main(String[] args) {
+        HelloModules.doSomething();
+
+        HelloModules module = new HelloModules();
+        module.sayHello();
+    }
+}

core-java-9/src/simple-modules/main.app/module-info.java

@@ -0,0 +1,4 @@
+module main.app {
+    requires hello.modules;
+    uses com.baeldung.modules.hello.HelloInterface;
+}

core-java-concurrency/README.md

@@ -34,3 +34,7 @@
 - [Implementing a Runnable vs Extending a Thread](http://www.baeldung.com/java-runnable-vs-extending-thread)
 - [How to Kill a Java Thread](http://www.baeldung.com/java-thread-stop)
 - [ExecutorService - Waiting for Threads to Finish](http://www.baeldung.com/java-executor-wait-for-threads)
+- [wait and notify() Methods in Java](http://www.baeldung.com/java-wait-notify)
+- [Priority-based Job Scheduling in Java](http://www.baeldung.com/java-priority-job-schedule)
+- [A Custom Spring SecurityConfigurer](http://www.baeldung.com/spring-security-custom-configurer)
+- [Life Cycle of a Thread in Java](http://www.baeldung.com/java-thread-lifecycle)

core-java-concurrency/src/test/java/com/baeldung/concurrent/volatilekeyword/SharedObjectManualTest.java

@@ -1,55 +1,36 @@
 package com.baeldung.concurrent.volatilekeyword;
 
-import org.junit.After;
-import org.junit.Before;
 import org.junit.Test;
 
-import static junit.framework.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 public class SharedObjectManualTest {
 
-    private SharedObject sharedObject;
-    private int valueReadByThread2;
-    private int valueReadByThread3;
-
-    @Before
-    public void setUp() {
-        sharedObject = new SharedObject();
-    }
-
     @Test
     public void whenOneThreadWrites_thenVolatileReadsFromMainMemory() throws InterruptedException {
+        SharedObject sharedObject = new SharedObject();
+
         Thread writer = new Thread(() -> sharedObject.increamentCount());
         writer.start();
-
+        Thread.sleep(100);
 
         Thread readerOne = new Thread(() -> {
-            try {
+            int valueReadByThread2 = sharedObject.getCount();
-                Thread.sleep(1000);
+            assertEquals(1, valueReadByThread2);
-            } catch (InterruptedException e) {
-                e.printStackTrace();
-            }
-            valueReadByThread2 = sharedObject.getCount();
         });
         readerOne.start();
 
         Thread readerTwo = new Thread(() -> {
-            try {
+            int valueReadByThread3 = sharedObject.getCount();
-                Thread.sleep(1000);
+            assertEquals(1, valueReadByThread3);
-            } catch (InterruptedException e) {
-                e.printStackTrace();
-            }
-            valueReadByThread3 = sharedObject.getCount();
         });
         readerTwo.start();
 
-        assertEquals(1, valueReadByThread2);
-        assertEquals(1, valueReadByThread3);
-
     }
 
     @Test
     public void whenTwoThreadWrites_thenVolatileReadsFromMainMemory() throws InterruptedException {
+        SharedObject sharedObject = new SharedObject();
         Thread writerOne = new Thread(() -> sharedObject.increamentCount());
         writerOne.start();
         Thread.sleep(100);
@@ -58,14 +39,17 @@ public class SharedObjectManualTest {
         writerTwo.start();
         Thread.sleep(100);
 
-        Thread readerOne = new Thread(() -> valueReadByThread2 = sharedObject.getCount());
+        Thread readerOne = new Thread(() -> {
+            int valueReadByThread2 = sharedObject.getCount();
+            assertEquals(2, valueReadByThread2);
+        });
         readerOne.start();
 
-        Thread readerTwo = new Thread(() -> valueReadByThread3 = sharedObject.getCount());
+        Thread readerTwo = new Thread(() -> {
+            int valueReadByThread3 = sharedObject.getCount();
+            assertEquals(2, valueReadByThread3);
+        });
         readerTwo.start();
 
-        assertEquals(2, valueReadByThread2);
-        assertEquals(2, valueReadByThread3);
-
     }
 }

core-java-io/pom.xml

@@ -6,7 +6,11 @@
     <packaging>jar</packaging>
 
     <name>core-java-io</name>
-
+	<parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
     <dependencies>
 
         <!-- utils -->

core-java-sun/pom.xml

@@ -6,7 +6,11 @@
     <packaging>jar</packaging>
 
     <name>core-java-sun</name>
-
+	<parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
     <dependencies>
 
         <!-- utils -->

core-java/.gitignore

@@ -16,7 +16,6 @@
 *.ear
 
 # Files generated by integration tests
-*.txt
 backup-pom.xml
 /bin/
 /temp

core-java/README.md

@@ -141,5 +141,14 @@
 - [Comparing Strings in Java](http://www.baeldung.com/java-compare-strings)
 - [Guide to Inheritance in Java](http://www.baeldung.com/java-inheritance)
 - [Guide to Externalizable Interface in Java](http://www.baeldung.com/java-externalizable)
-- [The “final” Keyword in Java](http://www.baeldung.com/java-final)
+- [The Observer Pattern in Java](https://github.com/eugenp/tutorials/tree/master/core-java)
+- [Flyweight Pattern in Java](http://www.baeldung.com/java-flyweight)
+- [Object Type Casting in Java](http://www.baeldung.com/java-type-casting)
+- [A Practical Guide to DecimalFormat](http://www.baeldung.com/java-decimalformat)
+- [How to Detect the OS Using Java](http://www.baeldung.com/java-detect-os)
+- [How to TDD a List Implementation in Java](http://www.baeldung.com/java-test-driven-list)
+- [ASCII Art in Java](http://www.baeldung.com/ascii-art-in-java)
+- [An Advanced Tagging Implementation with JPA](http://www.baeldung.com/jpa-tagging-advanced)
+- [Handling Daylight Savings Time in Java](http://www.baeldung.com/java-daylight-savings)
+- [Inheritance and Composition (Is-a vs Has-a relationship) in Java](http://www.baeldung.com/java-inheritance-composition)
 

core-java/pom.xml

@@ -7,7 +7,11 @@
     <packaging>jar</packaging>
 
     <name>core-java</name>
-
+	<parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
     <dependencies>
 
         <!-- utils -->
@@ -227,10 +231,9 @@
 			<version>1.5.8.RELEASE</version>
 		</dependency>
         <dependency>
-            <groupId>org.hsqldb</groupId>
+           <groupId>com.h2database</groupId>
-            <artifactId>hsqldb</artifactId>
+           <artifactId>h2</artifactId>
-            <version>2.4.0</version>
+           <version>1.4.197</version>
-            <scope>runtime</scope>
         </dependency>
     </dependencies>
 

core-java/src/main/java/com/baeldung/inheritancecomposition/application/Application.java

@@ -0,0 +1,27 @@
+package com.baeldung.inheritancecomposition.application;
+
+import com.baeldung.inheritancecomposition.model.Actress;
+import com.baeldung.inheritancecomposition.model.Computer;
+import com.baeldung.inheritancecomposition.model.StandardMemory;
+import com.baeldung.inheritancecomposition.model.Person;
+import com.baeldung.inheritancecomposition.model.StandardProcessor;
+import com.baeldung.inheritancecomposition.model.StandardSoundCard;
+import com.baeldung.inheritancecomposition.model.Waitress;
+
+public class Application {
+    
+    public static void main(String[] args) {
+        
+        Person person = new Person("John", "john@domain.com", 35);
+        Waitress waitress = new Waitress("Mary", "mary@domain.com", 22);
+        System.out.println(waitress.serveStarter("mixed salad"));
+        System.out.println(waitress.serveMainCourse("steak"));
+        System.out.println(waitress.serveDessert("cup of cofee"));
+        Actress actress = new Actress("Susan", "susan@domain.com", 30);
+        System.out.println(actress.readScript("Psycho"));
+        System.out.println(actress.performRole());
+        Computer computer = new Computer(new StandardProcessor("Intel I3"), new StandardMemory("Kingston", "1TB"));
+        computer.setSoundCard(new StandardSoundCard("Generic Sound Card"));
+        System.out.println(computer);
+    }
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/Actress.java

@@ -0,0 +1,16 @@
+package com.baeldung.inheritancecomposition.model;
+
+public class Actress extends Person {
+    
+    public Actress(String name, String email, int age) {
+        super(name, email, age);
+    }
+    
+    public String readScript(String movie) {
+        return "Reading the script of " + movie;
+    }
+    
+    public String performRole() {
+        return "Performing a role";
+    }
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/Computer.java

@@ -0,0 +1,36 @@
+package com.baeldung.inheritancecomposition.model;
+
+import java.util.Optional;
+
+public class Computer {
+
+    private Processor processor;
+    private Memory memory;
+    private SoundCard soundCard;
+
+    public Computer(Processor processor, Memory memory) {
+        this.processor = processor;
+        this.memory = memory;
+    }
+    
+    public void setSoundCard(SoundCard soundCard) {
+        this.soundCard = soundCard;
+    }
+    
+    public Processor getProcessor() {
+        return processor;
+    }
+
+    public Memory getMemory() {
+        return memory;
+    }
+    
+    public Optional<SoundCard> getSoundCard() {
+        return Optional.ofNullable(soundCard);
+    }
+    
+    @Override
+    public String toString() {
+        return "Computer{" + "processor=" + processor + ", memory=" + memory + ", soundcard=" + soundCard +"}";
+    }
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/Memory.java

@@ -0,0 +1,8 @@
+package com.baeldung.inheritancecomposition.model;
+
+public interface Memory {
+    
+    String getBrand();
+     
+    String getSize();   
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/Person.java

@@ -0,0 +1,31 @@
+package com.baeldung.inheritancecomposition.model;
+
+public class Person {
+    
+    private final String name;
+    private final String email;
+    private final int age;
+    
+    public Person(String name, String email, int age) {
+        this.name = name;
+        this.email = email;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    @Override
+    public String toString() {
+        return "Person{" + "name=" + name + ", email=" + email + ", age=" + age + "}";
+    }
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/Processor.java

@@ -0,0 +1,6 @@
+package com.baeldung.inheritancecomposition.model;
+
+public interface Processor {
+    
+    String getModel();
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/SoundCard.java

@@ -0,0 +1,6 @@
+package com.baeldung.inheritancecomposition.model;
+
+public interface SoundCard {
+    
+    String getBrand();
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/StandardMemory.java

@@ -0,0 +1,25 @@
+package com.baeldung.inheritancecomposition.model;
+
+public class StandardMemory implements Memory {
+    
+    private String brand;
+    private String size;
+
+    public StandardMemory(String brand, String size) {
+        this.brand = brand;
+        this.size = size;
+    }
+
+    public String getBrand() {
+        return brand;
+    }
+    
+    public String getSize() {
+        return size;
+    }
+
+    @Override
+    public String toString() {
+        return "Memory{" + "brand=" + brand + ", size=" + size + "}";
+    }
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/StandardProcessor.java

@@ -0,0 +1,20 @@
+package com.baeldung.inheritancecomposition.model;
+
+public class StandardProcessor implements Processor {
+
+    private String model;
+
+    public StandardProcessor(String model) {
+        this.model = model;
+    }
+
+    @Override
+    public String getModel() {
+        return model;
+    }
+    
+    @Override
+    public String toString() {
+        return "Processor{" + "model=" + model + "}";
+    }
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/StandardSoundCard.java

@@ -0,0 +1,20 @@
+package com.baeldung.inheritancecomposition.model;
+
+public class StandardSoundCard implements SoundCard {
+    
+    private String brand;
+
+    public StandardSoundCard(String brand) {
+        this.brand = brand;
+    }
+    
+    @Override
+    public String getBrand() {
+        return brand;
+    }
+    
+    @Override
+    public String toString() {
+        return "SoundCard{" + "brand=" + brand + "}";
+    }  
+}

core-java/src/main/java/com/baeldung/inheritancecomposition/model/Waitress.java

@@ -0,0 +1,20 @@
+package com.baeldung.inheritancecomposition.model;
+
+public class Waitress extends Person {
+    
+    public Waitress(String name, String email, int age) {
+        super(name, email, age);
+    }
+    
+    public String serveStarter(String starter) {
+        return "Serving a " + starter;
+    }
+    
+    public String serveMainCourse(String mainCourse) {
+        return "Serving a " + mainCourse;
+    }
+    
+    public String serveDessert(String dessert) {
+        return "Serving a " + dessert;
+    }
+}

core-java/src/main/java/com/baeldung/jdbc/BatchProcessing.java

@@ -13,8 +13,8 @@ public class BatchProcessing {
 
     public void getConnection(){
         try {
-            Class.forName("org.hsqldb.jdbcDriver");
+            Class.forName("org.h2.Driver");
-            connection = DriverManager.getConnection("jdbc:hsqldb:file:C:\\EMPLOYEEDB", "SA", "");
+            connection = DriverManager.getConnection("jdbc:h2:mem:db", "SA", "");
             connection.setAutoCommit(false);
         } catch (Exception e) {
             e.printStackTrace(System.out);

core-java/src/main/java/com/baeldung/ssl/SecureConnection.java

@@ -0,0 +1,54 @@
+package com.baeldung.ssl;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.SSLSocketFactory;
+
+public class SecureConnection {
+    
+    public static void main(String[] args) {
+        if (args.length != 2) {
+            System.out.println("Use: SecureConnection host port");
+            System.exit(1);
+        }
+        try {
+            String host = getHost(args);
+            Integer port = getPort(args);
+            SSLSocketFactory sslsocketfactory = (SSLSocketFactory) SSLSocketFactory.getDefault();
+            SSLSocket sslsocket = (SSLSocket) sslsocketfactory.createSocket(host, port);
+            InputStream in = sslsocket.getInputStream();
+            OutputStream out = sslsocket.getOutputStream();
+            
+            out.write(1);
+            
+            while (in.available() > 0) {
+                System.out.print(in.read());
+            }
+            
+            System.out.println("Secured connection performed successfully");
+            
+        } catch (Exception exception) {
+            exception.printStackTrace();
+        }
+    }
+    
+    /**
+     * Get the host from arguments
+     * @param args the arguments
+     * @return the host
+     */
+    private static String getHost(String[] args) {
+        return args[0];
+    }
+    
+    /**
+     * Get the port from arguments
+     * @param args the arguments
+     * @return the port
+     */
+    private static Integer getPort(String[] args) {
+        return Integer.parseInt(args[1]);
+    }
+}

core-java/src/main/java/com/baeldung/system/ChatWindow.java

@@ -0,0 +1,17 @@
+package com.baeldung.system;
+
+import java.awt.event.WindowEvent;
+
+/**
+ * Note: This class is not meant for unit-testing since it uses system
+ * features at low level and that it uses 'System' gc() which suggests
+ * JVM for garbage collection. But the usage below demonstrates how the
+ * method can be used.
+ */
+public class ChatWindow {
+    public void windowStateChanged(WindowEvent event) {
+        if (event.getNewState() == WindowEvent.WINDOW_DEACTIVATED ) {
+            System.gc(); // if it ends up running, great!
+        }
+    }
+}

core-java/src/main/java/com/baeldung/system/DateTimeService.java

@@ -0,0 +1,16 @@
+package com.baeldung.system;
+
+import java.util.Date;
+
+public class DateTimeService {
+
+    // One hour from now
+    public long nowPlusOneHour() {
+        return System.currentTimeMillis() + 3600 * 1000L;
+    }
+
+    // Human-readable format
+    public String nowPrettyPrinted() {
+        return new Date(System.currentTimeMillis()).toString();
+    }
+}

core-java/src/main/java/com/baeldung/system/EnvironmentVariables.java

@@ -0,0 +1,7 @@
+package com.baeldung.system;
+
+public class EnvironmentVariables {
+    public String getPath() {
+        return System.getenv("PATH");
+    }
+}

core-java/src/main/java/com/baeldung/system/SystemErrDemo.java

@@ -0,0 +1,18 @@
+package com.baeldung.system;
+
+/**
+ * Note: This class is not meant for unit-testing since it uses system
+ * features at low level and that it uses 'System' standard error stream
+ * methods to show output on screen. Also unit-tests in CI environments
+ * don't have console output for user to see messages. But the usage below
+ * demonstrates how the methods can be used.
+ */
+public class SystemErrDemo {
+    public static void main(String[] args) {
+        // Print without 'hitting' return
+        System.err.print("some inline error message");
+
+        // Print and then 'hit' return
+        System.err.println("an error message having new line at the end");
+    }
+}

core-java/src/main/java/com/baeldung/system/SystemExitDemo.java

@@ -0,0 +1,24 @@
+package com.baeldung.system;
+
+/**
+ * Note: This class is not meant for unit-testing since it uses system
+ * features at low level and that it uses 'System' exit() which will
+ * exit the JVM. Also unit-tests in CI environments are not meant to
+ * exit unit tests like that. But the usage below demonstrates how the
+ * method can be used.
+ */
+public class SystemExitDemo {
+    public static void main(String[] args) {
+        boolean error = false;
+
+        // do something and set error value
+
+        if (error) {
+            System.exit(1); // error case exit
+        } else {
+            System.exit(0); // normal case exit
+        }
+
+        // Will not do anything after exit()
+    }
+}

core-java/src/main/java/com/baeldung/system/SystemOutDemo.java

@@ -0,0 +1,25 @@
+package com.baeldung.system;
+
+import java.io.FileNotFoundException;
+import java.io.PrintStream;
+
+/**
+ * Note: This class is not meant for unit-testing since it uses system
+ * features at low level and that it uses 'System' standard output stream
+ * methods to show output on screen. Also unit-tests in CI environments
+ * don't have console output for user to see messages. But the usage below
+ * demonstrates how the methods can be used.
+ */
+public class SystemOutDemo {
+
+    public static void main(String[] args) throws FileNotFoundException {
+        // Print without 'hitting' return
+        System.out.print("some inline message");
+
+        // Print and then 'hit' return
+        System.out.println("a message having new line at the end");
+
+        // Changes output stream to send messages to file.
+        System.setOut(new PrintStream("file.txt"));
+    }
+}

core-java/src/main/java/com/baeldung/system/UserCredentials.java

@@ -0,0 +1,35 @@
+package com.baeldung.system;
+
+import java.io.BufferedReader;
+import java.io.Console;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+/**
+ * Note: This class is not meant for unit-testing since it uses system
+ * features at low level and that it uses 'System' standard input stream
+ * methods to read text from user. Also unit-tests in CI environments
+ * don't have console input for user to type in text. But the usage below
+ * demonstrates how the methods can be used.
+ */
+public class UserCredentials {
+
+    public String readUsername(int length) throws IOException {
+        byte[] name = new byte[length];
+        System.in.read(name, 0, length); // by default, from the console
+        return new String(name);
+    }
+
+    public String readUsername() throws IOException {
+        BufferedReader reader =
+                new BufferedReader(new InputStreamReader(System.in));
+        return reader.readLine();
+    }
+
+    public String readUsernameWithPrompt() {
+        Console console = System.console();
+
+        return console == null ? null : // Console not available
+                console.readLine("%s", "Enter your name: ");
+    }
+}

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

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

core-java/src/test/java/com/baeldung/array/converter/ArrayConvertToListTest.java

@@ -0,0 +1,116 @@
+package com.baeldung.array.converter;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.*;
+
+public class ArrayConvertToListTest {
+
+    @Test
+    public void givenAnStringArray_whenConvertArrayToList_thenListCreated() {
+        String[] flowers = { "Ageratum", "Allium", "Poppy", "Catmint" };
+        List<String> flowerList = Arrays.asList(flowers);
+
+        assertNotNull(flowerList);
+        assertEquals(flowerList.size(), 4);
+        assertEquals(flowerList.get(0), "Ageratum");
+        assertEquals(flowerList.get(1), "Allium");
+        assertEquals(flowerList.get(2), "Poppy");
+        assertEquals(flowerList.get(3), "Catmint");
+    }
+
+    @Test
+    public void givenAnIntArray_whenConvertArrayToList_thenListWithOneElementCreated() {
+        int[] primitives = { 1, 2, 3, 4 };
+        List numbers = Arrays.asList(primitives);
+
+        assertNotNull(numbers);
+        assertEquals(numbers.size(), 1);
+        assertEquals(numbers.get(0), primitives);
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void givenAnStringArray_whenConvertArrayToListAndAddAnElement_thenThrowUnsupportedOperationException() {
+        String[] flowers = { "Ageratum", "Allium", "Poppy", "Catmint" };
+        List<String> flowerList = Arrays.asList(flowers);
+
+        assertNotNull(flowerList);
+        assertEquals(flowerList.size(), 4);
+        assertEquals(flowerList.get(0), "Ageratum");
+        assertEquals(flowerList.get(1), "Allium");
+        assertEquals(flowerList.get(2), "Poppy");
+        assertEquals(flowerList.get(3), "Catmint");
+
+        flowerList.add("Celosia");
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void givenAnStringArray_whenConvertArrayToListAndRemoveAnElement_thenThrowUnsupportedOperationException() {
+        String[] flowers = { "Ageratum", "Allium", "Poppy", "Catmint" };
+        List<String> flowerList = Arrays.asList(flowers);
+
+        assertNotNull(flowerList);
+        assertEquals(flowerList.size(), 4);
+        assertEquals(flowerList.get(0), "Ageratum");
+        assertEquals(flowerList.get(1), "Allium");
+        assertEquals(flowerList.get(2), "Poppy");
+        assertEquals(flowerList.get(3), "Catmint");
+
+        flowerList.remove("Poppy");
+    }
+
+    @Test
+    public void givenAnStringArray_whenCreateListFromArrayAndAddAnElement_thenListOk() {
+        String[] flowers = { "Ageratum", "Allium", "Poppy", "Catmint" };
+        List<String> flowerList = Arrays.asList(flowers);
+
+        assertNotNull(flowerList);
+        assertEquals(flowerList.size(), 4);
+
+        assertEquals(flowerList.get(0), "Ageratum");
+        assertEquals(flowerList.get(1), "Allium");
+        assertEquals(flowerList.get(2), "Poppy");
+        assertEquals(flowerList.get(3), "Catmint");
+
+        List<String> newflowerList = new ArrayList<>(flowerList);
+
+        assertNotNull(newflowerList);
+        assertEquals(newflowerList.size(), 4);
+        assertEquals(newflowerList.get(0), "Ageratum");
+        assertEquals(newflowerList.get(1), "Allium");
+        assertEquals(newflowerList.get(2), "Poppy");
+        assertEquals(newflowerList.get(3), "Catmint");
+
+        newflowerList.add("Celosia");
+
+        assertEquals(newflowerList.size(), 5);
+        assertEquals(newflowerList.get(4), "Celosia");
+    }
+
+    @Test
+    public void givenAnStringArray_whenIterateArrayAndAddTheElementsToNewListAndAddAnElement_thenListOk() {
+        String[] flowers = { "Ageratum", "Allium", "Poppy", "Catmint" };
+
+        List<String> flowerList = new ArrayList<>();
+        for(String flower: flowers) {
+            flowerList.add(flower);
+        }
+
+        assertNotNull(flowerList);
+        assertEquals(flowerList.size(), 4);
+
+        assertEquals(flowerList.get(0), "Ageratum");
+        assertEquals(flowerList.get(1), "Allium");
+        assertEquals(flowerList.get(2), "Poppy");
+        assertEquals(flowerList.get(3), "Catmint");
+
+        flowerList.add("Celosia");
+
+        assertEquals(flowerList.size(), 5);
+        assertEquals(flowerList.get(4), "Celosia");
+    }
+}

core-java/src/test/java/com/baeldung/inheritancecomposition/test/ActressUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Actress;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class ActressUnitTest {
+    
+    private static Actress actress;
+    
+    @BeforeClass
+    public static void setUpActressInstance() {
+        actress = new Actress("Susan", "susan@domain.com", 30);
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledgetName_thenEqual() {
+        assertThat(actress.getName()).isEqualTo("Susan");
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledgetEmail_thenEqual() {
+        assertThat(actress.getEmail()).isEqualTo("susan@domain.com");
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledgetAge_thenEqual() {
+        assertThat(actress.getAge()).isEqualTo(30);
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledreadScript_thenEqual() {
+        assertThat(actress.readScript("Psycho")).isEqualTo("Reading the script of Psycho");
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledperfomRole_thenEqual() {
+        assertThat(actress.performRole()).isEqualTo("Performing a role");
+    }
+}

core-java/src/test/java/com/baeldung/inheritancecomposition/test/CompositionUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Computer;
+import com.baeldung.inheritancecomposition.model.Memory;
+import com.baeldung.inheritancecomposition.model.Processor;
+import com.baeldung.inheritancecomposition.model.StandardMemory;
+import com.baeldung.inheritancecomposition.model.StandardProcessor;
+import com.baeldung.inheritancecomposition.model.StandardSoundCard;
+import java.util.Optional;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class CompositionUnitTest {
+    
+    
+    @Test
+    public void givenComputerInstance_whenExtractedEachField_thenThreeAssertions() {
+        Computer computer = new Computer(new StandardProcessor("Intel I3"), new StandardMemory("Kingston", "1TB"));
+        computer.setSoundCard(new StandardSoundCard("Generic Sound Card"));
+        assertThat(computer.getProcessor()).isInstanceOf(Processor.class);
+        assertThat(computer.getMemory()).isInstanceOf(Memory.class);
+        assertThat(computer.getSoundCard()).isInstanceOf(Optional.class);
+    }
+}

core-java/src/test/java/com/baeldung/inheritancecomposition/test/InheritanceUnitTest.java

@@ -0,0 +1,20 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Actress;
+import com.baeldung.inheritancecomposition.model.Person;
+import com.baeldung.inheritancecomposition.model.Waitress;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class InheritanceUnitTest {
+    
+    @Test
+    public void givenWaitressInstance_whenCheckedType_thenIsInstanceOfPerson() {
+        assertThat(new Waitress("Mary", "mary@domain.com", 22)).isInstanceOf(Person.class);
+    }
+    
+    @Test
+    public void givenActressInstance_whenCheckedType_thenIsInstanceOfPerson() {
+        assertThat(new Actress("Susan", "susan@domain.com", 30)).isInstanceOf(Person.class);
+    }
+}

core-java/src/test/java/com/baeldung/inheritancecomposition/test/PersonUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Person;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class PersonUnitTest {
+    
+    private static Person person;
+    
+    @BeforeClass
+    public static void setPersonInstance() {
+        person = new Person("John", "john@domain.com", 35);
+    }
+    
+    @Test
+    public void givenPersonInstance_whenCalledgetName_thenEqual() {
+        assertThat(person.getName()).isEqualTo("John");
+    }
+    
+    @Test
+    public void givenPersonInstance_whenCalledgetEmail_thenEqual() {
+        assertThat(person.getEmail()).isEqualTo("john@domain.com");
+    }
+    
+    @Test
+    public void givenPersonInstance_whenCalledgetAge_thenEqual() {
+        assertThat(person.getAge()).isEqualTo(35);
+    }
+}

core-java/src/test/java/com/baeldung/inheritancecomposition/test/WaitressUnitTest.java

@@ -0,0 +1,46 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Waitress;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class WaitressUnitTest {
+
+    private static Waitress waitress;
+
+    @BeforeClass
+    public static void setUpWaitressInstance() {
+        waitress = new Waitress("Mary", "mary@domain.com", 22);
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledgetName_thenOneAssertion() {
+        assertThat(waitress.getName()).isEqualTo("Mary");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledgetEmail_thenOneAssertion() {
+        assertThat(waitress.getEmail()).isEqualTo("mary@domain.com");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledgetAge_thenOneAssertion() {
+        assertThat(waitress.getAge()).isEqualTo(22);
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledserveStarter_thenOneAssertion() {
+        assertThat(waitress.serveStarter("mixed salad")).isEqualTo("Serving a mixed salad");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledserveMainCourse_thenOneAssertion() {
+        assertThat(waitress.serveMainCourse("steak")).isEqualTo("Serving a steak");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledserveDessert_thenOneAssertion() {
+        assertThat(waitress.serveDessert("cup of coffee")).isEqualTo("Serving a cup of coffee");
+    }
+}

core-java/src/test/java/com/baeldung/system/DateTimeServiceTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.system;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DateTimeServiceTest {
+
+    @Test
+    public void givenClass_whenCalledMethods_thenNotNullInResult() {
+        DateTimeService dateTimeService = new DateTimeService();
+
+        Assert.assertNotNull(dateTimeService.nowPlusOneHour());
+        Assert.assertNotNull(dateTimeService.nowPrettyPrinted());
+    }
+}

core-java/src/test/java/com/baeldung/system/EnvironmentVariablesTest.java

@@ -0,0 +1,14 @@
+package com.baeldung.system;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class EnvironmentVariablesTest {
+
+    @Test
+    public void givenEnvVars_whenReadPath_thenGetValueinResult() {
+        EnvironmentVariables environmentVariables = new EnvironmentVariables();
+
+        Assert.assertNotNull(environmentVariables.getPath());
+    }
+}

core-java/src/test/java/com/baeldung/system/SystemArrayCopyTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.system;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class SystemArrayCopyTest {
+
+    @Test
+    public void givenTwoArraysAB_whenUseArrayCopy_thenArrayCopiedFromAToBInResult() {
+        int[] a = {34, 22, 44, 2, 55, 3};
+        int[] b = new int[a.length];
+
+        // copy all elements from a to b
+        System.arraycopy(a, 0, b, 0, a.length);
+        Assert.assertArrayEquals(a, b);
+    }
+
+    @Test
+    public void givenTwoArraysAB_whenUseArrayCopyPosition_thenArrayCopiedFromAToBInResult() {
+        int[] a = {34, 22, 44, 2, 55, 3};
+        int[] b = new int[a.length];
+
+        // copy 2 elements from a, starting at a[1] to b, starting at b[3]
+        System.arraycopy(a, 1, b, 3, 2);
+        Assert.assertArrayEquals(new int[] {0, 0, 0, 22, 44, 0}, b);
+    }
+}

core-java/src/test/java/com/baeldung/system/SystemNanoTest.java

@@ -0,0 +1,16 @@
+package com.baeldung.system;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class SystemNanoTest {
+
+    @Test
+    public void givenSystem_whenCalledNanoTime_thenGivesTimeinResult() {
+        long startTime = System.nanoTime();
+        // do something that takes time
+        long endTime = System.nanoTime();
+
+        Assert.assertTrue(endTime - startTime < 10000);
+    }
+}

core-java/src/test/java/com/baeldung/system/SystemPropertiesTest.java

@@ -0,0 +1,56 @@
+package com.baeldung.system;
+
+import org.junit.Assert;
+import org.junit.Ignore;
+import org.junit.Test;
+
+import java.util.Properties;
+
+public class SystemPropertiesTest {
+
+    @Test
+    public void givenSystem_whenCalledGetProperty_thenReturnPropertyinResult() {
+        Assert.assertNotNull(System.getProperty("java.vm.vendor"));
+    }
+
+    @Test
+    public void givenSystem_whenCalledSetProperty_thenSetPropertyasResult() {
+
+        // set a particular property
+        System.setProperty("abckey", "abcvaluefoo");
+        Assert.assertEquals("abcvaluefoo", System.getProperty("abckey"));
+    }
+
+    @Test
+    public void givenSystem_whenCalledClearProperty_thenDeletePropertyasResult() {
+
+        // Delete a property
+        System.clearProperty("abckey");
+        Assert.assertNull(System.getProperty("abckey"));
+    }
+
+    @Test
+    public void givenSystem_whenCalledGetPropertyDefaultValue_thenReturnPropertyinResult() {
+
+        System.clearProperty("dbHost");
+        String myKey = System.getProperty("dbHost", "db.host.com");
+        Assert.assertEquals("db.host.com", myKey);
+    }
+
+    @Test
+    public void givenSystem_whenCalledGetProperties_thenReturnPropertiesinResult() {
+        Properties properties = System.getProperties();
+
+        Assert.assertNotNull(properties);
+    }
+
+    @Test
+    @Ignore
+    public void givenSystem_whenCalledClearProperties_thenDeleteAllPropertiesasResult() {
+
+        // Clears all system properties. Use with care!
+        System.getProperties().clear();
+
+        Assert.assertTrue(System.getProperties().isEmpty());
+    }
+}