Merge branch 'master' of https://github.com/eugenp/tutorials

.gitignore

@@ -65,6 +65,7 @@ core-java-io/target_link.txt
 core-java/src/main/java/com/baeldung/manifest/MANIFEST.MF
 ethereum/logs/
 jmeter/src/main/resources/*-JMeter.csv
+ninja/devDb.mv.db
 
 **/node_modules/
 **/dist

algorithms-miscellaneous-5/README.md

@@ -13,4 +13,11 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
 - [Overview of Combinatorial Problems in Java](https://www.baeldung.com/java-combinatorial-algorithms)
 - [Prim’s Algorithm](https://www.baeldung.com/java-prim-algorithm)
+- [Maximum Subarray Problem](https://www.baeldung.com/java-maximum-subarray)
+- [How to Merge Two Sorted Arrays](https://www.baeldung.com/java-merge-sorted-arrays)
+- [Median of Stream of Integers using Heap](https://www.baeldung.com/java-stream-integers-median-using-heap)
+- [Kruskal’s Algorithm for Spanning Trees](https://www.baeldung.com/java-spanning-trees-kruskal)
+- [Balanced Brackets Algorithm in Java](https://www.baeldung.com/java-balanced-brackets-algorithm)
+- [Efficiently Merge Sorted Java Sequences](https://www.baeldung.com/java-merge-sorted-sequences)
+- [Introduction to Greedy Algorithms with Java](https://www.baeldung.com/java-greedy-algorithms)
 - More articles: [[<-- prev]](/../algorithms-miscellaneous-4)

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/balancedbinarytree/AVLTree.java

@@ -0,0 +1,141 @@
+package com.baeldung.algorithms.balancedbinarytree;
+
+public class AVLTree {
+
+    public class Node {
+        int key;
+        int height;
+        Node left;
+        Node right;
+
+        Node(int key) {
+            this.key = key;
+        }
+    }
+
+    private Node root;
+
+    public Node find(int key) {
+        Node current = root;
+        while (current != null) {
+            if (current.key == key) {
+               break;
+            }
+            current = current.key < key ? current.right : current.left;
+        }
+        return current;
+    }
+
+    public void insert(int key) {
+        root = insert(root, key);
+    }
+
+    public void delete(int key) {
+        root = delete(root, key);
+    }
+
+    public Node getRoot() {
+        return root;
+    }
+
+    public int height() {
+        return root == null ? -1 : root.height;
+    }
+
+    private Node insert(Node node, int key) {
+        if (node == null) {
+            return new Node(key);
+        } else if (node.key > key) {
+            node.left = insert(node.left, key);
+        } else if (node.key < key) {
+            node.right = insert(node.right, key);
+        } else {
+            throw new RuntimeException("duplicate Key!");
+        }
+        return rebalance(node);
+    }
+
+    private Node delete(Node node, int key) {
+        if (node == null) {
+            return node;
+        } else if (node.key > key) {
+            node.left = delete(node.left, key);
+        } else if (node.key < key) {
+            node.right = delete(node.right, key);
+        } else {
+            if (node.left == null || node.right == null) {
+                node = (node.left == null) ? node.right : node.left;
+            } else {
+                Node mostLeftChild = mostLeftChild(node.right);
+                node.key = mostLeftChild.key;
+                node.right = delete(node.right, node.key);
+            }
+        }
+        if (node != null) {
+            node = rebalance(node);
+        }
+        return node;
+    }
+
+    private Node mostLeftChild(Node node) {
+        Node current = node;
+        /* loop down to find the leftmost leaf */
+        while (current.left != null) {
+            current = current.left;
+        }
+        return current;
+    }
+
+    private Node rebalance(Node z) {
+        updateHeight(z);
+        int balance = getBalance(z);
+        if (balance > 1) {
+            if (height(z.right.right) > height(z.right.left)) {
+                z = rotateLeft(z);
+            } else {
+                z.right = rotateRight(z.right);
+                z = rotateLeft(z);
+            }
+        } else if (balance < -1) {
+            if (height(z.left.left) > height(z.left.right)) {
+                z = rotateRight(z);
+            } else {
+                z.left = rotateLeft(z.left);
+                z = rotateRight(z);
+            }
+        }
+        return z;
+    }
+
+    private Node rotateRight(Node y) {
+        Node x = y.left;
+        Node z = x.right;
+        x.right = y;
+        y.left = z;
+        updateHeight(y);
+        updateHeight(x);
+        return x;
+    }
+
+    private Node rotateLeft(Node y) {
+        Node x = y.right;
+        Node z = x.left;
+        x.left = y;
+        y.right = z;
+        updateHeight(y);
+        updateHeight(x);
+        return x;
+    }
+
+    private void updateHeight(Node n) {
+        n.height = 1 + Math.max(height(n.left), height(n.right));
+    }
+
+    private int height(Node n) {
+        return n == null ? -1 : n.height;
+    }
+
+    public int getBalance(Node n) {
+        return (n == null) ? 0 : height(n.right) - height(n.left);
+    }
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/balancedbinarytree/AVLTreeUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.algorithms.balancedbinarytree;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class AVLTreeUnitTest {
+
+    @Test
+    public void givenEmptyTree_whenHeightCalled_shouldReturnMinus1() {
+        AVLTree tree = new AVLTree();
+        Assert.assertEquals(-1, tree.height());
+    }
+
+    @Test
+    public void givenEmptyTree_whenInsertCalled_heightShouldBeZero() {
+        AVLTree tree = new AVLTree();
+        tree.insert(1);
+        Assert.assertEquals(0, tree.height());
+    }
+
+    @Test
+    public void givenEmptyTree_whenInsertCalled_treeShouldBeAvl() {
+        AVLTree tree = new AVLTree();
+        tree.insert(1);
+        Assert.assertTrue(isAVL(tree));
+    }
+
+    @Test
+    public void givenSampleTree_whenInsertCalled_treeShouldBeAvl() {
+        AVLTree tree = getSampleAVLTree();
+        int newKey = 11;
+        tree.insert(newKey);
+        Assert.assertTrue(isAVL(tree));
+    }
+
+    @Test
+    public void givenSampleTree_whenFindExistingKeyCalled_shouldReturnMatchedNode() {
+        AVLTree tree = getSampleAVLTree();
+        int existingKey = 2;
+        AVLTree.Node result = tree.find(existingKey);
+        Assert.assertEquals(result.key, existingKey);
+    }
+
+    @Test
+    public void givenSampleTree_whenFindNotExistingKeyCalled_shouldReturnNull() {
+        AVLTree tree = getSampleAVLTree();
+        int notExistingKey = 11;
+        AVLTree.Node result = tree.find(notExistingKey);
+        Assert.assertNull(result);
+    }
+
+    @Test
+    public void givenEmptyTree_whenDeleteCalled_treeShouldBeAvl() {
+        AVLTree tree = new AVLTree();
+        tree.delete(1);
+        Assert.assertTrue(isAVL(tree));
+    }
+
+    @Test
+    public void givenSampleTree_whenDeleteCalled_treeShouldBeAvl() {
+        AVLTree tree = getSampleAVLTree();
+        tree.delete(1);
+        Assert.assertTrue(isAVL(tree, tree.getRoot()));
+    }
+
+    private boolean isAVL(AVLTree tree) {
+       return isAVL(tree, tree.getRoot());
+    }
+
+    private boolean isAVL(AVLTree tree, AVLTree.Node node) {
+        if ( node == null )
+            return true;
+        int balance = tree.getBalance(node);
+        return (balance <= 1 && balance >= -1) && isAVL(tree, node.left) && isAVL(tree, node.right);
+    }
+
+    private AVLTree getSampleAVLTree() {
+        AVLTree avlTree = new AVLTree();
+        for (int i = 0; i < 10; i++)
+            avlTree.insert(i);
+        return avlTree;
+    }
+}

algorithms-sorting-2/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Partitioning and Sorting Arrays with Many Repeated Entries](https://www.baeldung.com/java-sorting-arrays-with-repeated-entries)

apache-poi/README.md

@@ -6,3 +6,6 @@ This module contains articles about Apache POI
 - [Microsoft Word Processing in Java with Apache POI](https://www.baeldung.com/java-microsoft-word-with-apache-poi)
 - [Working with Microsoft Excel in Java](https://www.baeldung.com/java-microsoft-excel)
 - [Creating a MS PowerPoint Presentation in Java](https://www.baeldung.com/apache-poi-slideshow)
+- [Merge Cells in Excel Using Apache POI](https://www.baeldung.com/java-apache-poi-merge-cells)
+- [Get String Value of Excel Cell with Apache POI](https://www.baeldung.com/java-apache-poi-cell-string-value)
+- [Read Excel Cell Value Rather Than Formula With Apache POI](https://github.com/eugenp/tutorials/tree/master/apache-poi)

apache-poi/src/test/java/com/baeldung/poi/excel/merge/ExcelCellMergerUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.poi.excel;
+package com.baeldung.poi.excel.merge;
 
 import static org.junit.Assert.assertEquals;
 

apache-rocketmq/README.md

@@ -3,3 +3,5 @@
 This module contains articles about Apache RocketMQ
 
 ### Relevant Articles: 
+
+- [Apache RocketMQ with Spring Boot](https://www.baeldung.com/apache-rocketmq-spring-boot)

aws-reactive/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [AWS S3 with Java – Reactive Support](https://www.baeldung.com/java-aws-s3-reactive)

core-java-modules/core-java-11/README.md

@@ -13,3 +13,4 @@ This module contains articles about Java 11 core features
 - [Guide to jlink](https://www.baeldung.com/jlink)
 - [Negate a Predicate Method Reference with Java 11](https://www.baeldung.com/java-negate-predicate-method-reference)
 - [Benchmark JDK Collections vs Eclipse Collections](https://www.baeldung.com/jdk-collections-vs-eclipse-collections)
+- [Pre-compile Regex Patterns Into Pattern Objects](https://www.baeldung.com/java-regex-pre-compile)

core-java-modules/core-java-13/README.md

@@ -1,3 +1,4 @@
 ### Relevant articles:
 
 - [Java Switch Statement](https://www.baeldung.com/java-switch)
+- [New Java 13 Features](https://www.baeldung.com/java-13-new-features)

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

@@ -13,4 +13,5 @@ This module contains articles about Java arrays
 - [Removing an Element from an Array in Java](https://www.baeldung.com/java-array-remove-element)
 - [Removing the First Element of an Array](https://www.baeldung.com/java-array-remove-first-element)
 - [Adding an Element to a Java Array vs an ArrayList](https://www.baeldung.com/java-add-element-to-array-vs-list)
+- [Arrays.sort vs Arrays.parallelSort](https://www.baeldung.com/java-arrays-sort-vs-parallelsort)
 - [[<-- Prev]](/core-java-modules/core-java-arrays)

core-java-modules/core-java-arrays-2/src/test/java/com/baeldung/arraysort/SortComparisonUnitTest.java

@@ -69,7 +69,7 @@ public class SortComparisonUnitTest {
     }
 
     @Test
-    public void givenArrayOfIntegers_whenUsingArraysSortMethodWithRange_thenSortRangeOfArrayInAscendingOrder() {
+    public void givenArrayOfIntegers_whenUsingArraysSortWithRange_thenSortRangeOfArrayAsc() {
         int[] array = { 10, 4, 6, 2, 1, 9, 7, 8, 3, 5 };
         int[] expected = { 10, 4, 1, 2, 6, 7, 8, 9, 3, 5 };
 
@@ -89,7 +89,7 @@ public class SortComparisonUnitTest {
     }
 
     @Test
-    public void givenArrayOfIntegers_whenUsingArraysParallelSortMethodWithRange_thenSortRangeOfArrayInAscendingOrder() {
+    public void givenArrayOfIntegers_whenUsingArraysParallelSortWithRange_thenSortRangeOfArrayAsc() {
         int[] array = { 10, 4, 6, 2, 1, 9, 7, 8, 3, 5 };
         int[] expected = { 10, 4, 1, 2, 6, 7, 8, 9, 3, 5 };
 

core-java-modules/core-java-concurrency-advanced-3/README.md

@@ -8,4 +8,6 @@ This module contains articles about advanced topics about multithreading with co
 
 - [Common Concurrency Pitfalls in Java](https://www.baeldung.com/java-common-concurrency-pitfalls)
 - [Guide to RejectedExecutionHandler](https://www.baeldung.com/java-rejectedexecutionhandler)
-[[<-- previous]](/core-java-modules/core-java-concurrency-advanced-2)
+- [Guide to Work Stealing in Java](https://www.baeldung.com/java-work-stealing)
+- [Asynchronous Programming in Java](https://www.baeldung.com/java-asynchronous-programming)
+- [[<-- previous]](/core-java-modules/core-java-concurrency-advanced-2)

core-java-modules/core-java-concurrency-advanced/src/main/java/com/baeldung/concurrent/volatilekeyword/SharedObject.java

@@ -4,7 +4,7 @@ package com.baeldung.concurrent.volatilekeyword;
 public class SharedObject {
     private volatile int count=0;
 
-    void increamentCount(){
+    void incrementCount(){
         count++;
     }
     public int  getCount(){

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

@@ -10,7 +10,7 @@ public class SharedObjectManualTest {
     public void whenOneThreadWrites_thenVolatileReadsFromMainMemory() throws InterruptedException {
         SharedObject sharedObject = new SharedObject();
 
-        Thread writer = new Thread(() -> sharedObject.increamentCount());
+        Thread writer = new Thread(() -> sharedObject.incrementCount());
         writer.start();
         Thread.sleep(100);
 
@@ -31,11 +31,11 @@ public class SharedObjectManualTest {
     @Test
     public void whenTwoThreadWrites_thenVolatileReadsFromMainMemory() throws InterruptedException {
         SharedObject sharedObject = new SharedObject();
-        Thread writerOne = new Thread(() -> sharedObject.increamentCount());
+        Thread writerOne = new Thread(() -> sharedObject.incrementCount());
         writerOne.start();
         Thread.sleep(100);
 
-        Thread writerTwo = new Thread(() -> sharedObject.increamentCount());
+        Thread writerTwo = new Thread(() -> sharedObject.incrementCount());
         writerTwo.start();
         Thread.sleep(100);
 

core-java-modules/core-java-date-operations-2/README.md

@@ -6,4 +6,5 @@ This module contains articles about date operations in Java.
 - [Skipping Weekends While Adding Days to LocalDate in Java 8](https://www.baeldung.com/java-localdate-add-days-skip-weekends)
 - [Checking If Two Java Dates Are on the Same Day](https://www.baeldung.com/java-check-two-dates-on-same-day)
 - [Converting Java Date to OffsetDateTime](https://www.baeldung.com/java-convert-date-to-offsetdatetime)
+- [How to Set the JVM Time Zone](https://www.baeldung.com/java-jvm-time-zone)
 - [[<-- Prev]](/core-java-modules/core-java-date-operations-1)

core-java-modules/core-java-datetime-java8-2/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Creating a LocalDate with Values in Java](https://www.baeldung.com/java-creating-localdate-with-values)

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

@@ -5,3 +5,5 @@ This module contains articles about core java exceptions
 ### Relevant Articles:
 
 - [Is It a Bad Practice to Catch Throwable?](https://www.baeldung.com/java-catch-throwable-bad-practice)
+- [Wrapping vs Rethrowing Exceptions in Java](https://www.baeldung.com/java-wrapping-vs-rethrowing-exceptions)
+- [java.net.UnknownHostException: Invalid Hostname for Server](https://www.baeldung.com/java-unknownhostexception)

core-java-modules/core-java-exceptions-2/src/main/java/com/baeldung/socketexception/SocketClient.java

@@ -0,0 +1,32 @@
+package com.baeldung.socketexception;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.net.Socket;
+
+public class SocketClient {
+
+    private Socket clientSocket;
+    private PrintWriter out;
+    private BufferedReader in;
+
+    public void startConnection(String ip, int port) throws IOException {
+        clientSocket = new Socket(ip, port);
+        out = new PrintWriter(clientSocket.getOutputStream(), true);
+        in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
+    }
+
+    public String sendMessage(String msg) throws IOException {
+        out.println(msg);
+        return in.readLine();
+    }
+
+    public void stopConnection() throws IOException {
+        in.close();
+        out.close();
+        clientSocket.close();
+    }
+
+}

core-java-modules/core-java-exceptions-2/src/main/java/com/baeldung/socketexception/SocketServer.java

@@ -0,0 +1,45 @@
+package com.baeldung.socketexception;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.net.ServerSocket;
+import java.net.Socket;
+
+public class SocketServer {
+
+    private ServerSocket serverSocket;
+    private Socket clientSocket;
+    private PrintWriter out;
+    private BufferedReader in;
+
+    public void start(int port) {
+        try {
+            serverSocket = new ServerSocket(port);
+            clientSocket = serverSocket.accept();
+            out = new PrintWriter(clientSocket.getOutputStream(), true);
+            in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
+            String msg = in.readLine();
+            if (msg.contains("hi"))
+                out.println("hi");
+            else
+                out.println("didn't understand");
+            close();
+            stop();
+        } catch (IOException e) {
+            
+        }
+    }
+
+    private void close() throws IOException {
+        in.close();
+        out.close();
+    }
+
+    private void stop() throws IOException {
+        clientSocket.close();
+        serverSocket.close();
+    }
+
+}

core-java-modules/core-java-exceptions-2/src/test/java/com/baeldung/socketexception/SocketExceptionHandlingUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.socketexception;
+
+import java.io.IOException;
+import java.net.SocketException;
+import java.util.concurrent.Executors;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class SocketExceptionHandlingUnitTest {
+
+    @BeforeClass
+    public static void runServer() throws IOException, InterruptedException {
+        Executors.newSingleThreadExecutor()
+            .submit(() -> new SocketServer().start(6699));
+        Thread.sleep(100);
+    }
+
+    @Test
+    public void givenRunningServer_whenConnectToClosedSocket_thenHandleException() throws IOException {
+        SocketClient client = new SocketClient();
+        client.startConnection("127.0.0.1", 6699);
+        try {
+            client.sendMessage("hi");
+            client.sendMessage("hi again");
+        } catch (SocketException e) {
+            client.stopConnection();
+        }
+    }
+
+}

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

@@ -6,4 +6,7 @@ This module contains articles about core features in the Java language
 - [Java Primitives versus Objects](https://www.baeldung.com/java-primitives-vs-objects)
 - [Command-Line Arguments in Java](https://www.baeldung.com/java-command-line-arguments)
 - [What is a POJO Class?](https://www.baeldung.com/java-pojo-class)
+- [Java Default Parameters Using Method Overloading](https://www.baeldung.com/java-default-parameters-method-overloading)
+- [How to Return Multiple Values From a Java Method](https://www.baeldung.com/java-method-return-multiple-values)
+- [Guide to the Java finally Keyword](https://www.baeldung.com/java-finally-keyword)
 - [[<-- Prev]](/core-java-modules/core-java-lang)

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/headlessmode/FlexibleApp.java

@@ -0,0 +1,27 @@
+package com.baeldung.headlessmode;
+
+import java.awt.GraphicsEnvironment;
+
+import javax.swing.JOptionPane;
+
+public class FlexibleApp {
+    public static final int HEADLESS = 0;
+    public static final int HEADED = 1;
+    public FlexibleApp() {
+
+        if (GraphicsEnvironment.isHeadless()) {
+            System.out.println("Hello World");
+        } else {
+            JOptionPane.showMessageDialog(null, "Hello World");
+        }
+
+    }
+    
+    public static int iAmFlexible() {
+        if (GraphicsEnvironment.isHeadless()) {
+            return HEADLESS;
+        } else {
+            return HEADED;
+        }
+    }
+}

core-java-modules/core-java-lang-2/src/test/java/com/baeldung/headlessmode/HeadlessModeUnitTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.headlessmode;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+import java.awt.Canvas;
+import java.awt.Font;
+import java.awt.FontMetrics;
+import java.awt.Frame;
+import java.awt.GraphicsEnvironment;
+import java.awt.HeadlessException;
+import java.awt.image.BufferedImage;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import javax.imageio.ImageIO;
+
+import org.junit.Assume;
+import org.junit.Before;
+import org.junit.Test;
+
+public class HeadlessModeUnitTest {
+
+    private static final String IN_FILE = "/product.png";
+    private static final String OUT_FILE = System.getProperty("java.io.tmpdir") + "/product.jpg";
+    private static final String FORMAT = "jpg";
+
+    @Before
+    public void setUpHeadlessMode() {
+        System.setProperty("java.awt.headless", "true");
+    }
+
+    @Test
+    public void whenJavaAwtHeadlessSetToTrue_thenIsHeadlessReturnsTrue() {
+        assertThat(GraphicsEnvironment.isHeadless()).isTrue();
+    }
+
+    @Test
+    public void whenHeadlessMode_thenFontsWork() {
+        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
+
+        String fonts[] = ge.getAvailableFontFamilyNames();
+
+        assertThat(fonts).isNotEmpty();
+
+        Font font = new Font(fonts[0], Font.BOLD, 14);
+
+        FontMetrics fm = (new Canvas()).getFontMetrics(font);
+
+        assertThat(fm.getHeight()).isGreaterThan(0);
+        assertThat(fm.getAscent()).isGreaterThan(0);
+        assertThat(fm.getDescent()).isGreaterThan(0);
+    }
+
+    @Test
+    public void whenHeadlessMode_thenImagesWork() throws IOException {
+        boolean result = false;
+        try (InputStream inStream = HeadlessModeUnitTest.class.getResourceAsStream(IN_FILE); FileOutputStream outStream = new FileOutputStream(OUT_FILE)) {
+            BufferedImage inputImage = ImageIO.read(inStream);
+            result = ImageIO.write(inputImage, FORMAT, outStream);
+        }
+
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void whenHeadlessmode_thenFrameThrowsHeadlessException() {
+        assertThatExceptionOfType(HeadlessException.class).isThrownBy(() -> {
+            Frame frame = new Frame();
+            frame.setVisible(true);
+            frame.setSize(120, 120);
+        });
+    }    
+
+    @Test
+    public void whenHeadless_thenFlexibleAppAdjustsItsBehavior() {
+        assertThat(FlexibleApp.iAmFlexible()).isEqualTo(FlexibleApp.HEADLESS);
+    }
+
+    @Test
+    public void whenHeaded_thenFlexibleAppAdjustsItsBehavior() {
+        Assume.assumeFalse(GraphicsEnvironment.isHeadless());
+        assertThat(FlexibleApp.iAmFlexible()).isEqualTo(FlexibleApp.HEADED);
+    }
+
+}

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

@@ -9,3 +9,4 @@
 - [The strictfp Keyword in Java](https://www.baeldung.com/java-strictfp)
 - [Basic Calculator in Java](https://www.baeldung.com/java-basic-calculator)
 - [Overflow and Underflow in Java](https://www.baeldung.com/java-overflow-underflow)
+- [Obtaining a Power Set of a Set in Java](https://www.baeldung.com/java-power-set-of-a-set)

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

@@ -13,4 +13,5 @@ This module contains articles about Object-oriented programming (OOP) in Java
 - [The “final” Keyword in Java](https://www.baeldung.com/java-final)
 - [Type Erasure in Java Explained](https://www.baeldung.com/java-type-erasure)
 - [Variable and Method Hiding in Java](https://www.baeldung.com/java-variable-method-hiding)
+- [Object-Oriented-Programming Concepts in Java](https://www.baeldung.com/java-oop)
 - [[More -->]](/core-java-modules/core-java-lang-oop-2)

core-java-modules/core-java-lang-syntax-2/README.md

@@ -12,4 +12,5 @@ This module contains articles about Java syntax
 - [Variable Scope in Java](https://www.baeldung.com/java-variable-scope)
 - [Introduction to Basic Syntax in Java](https://www.baeldung.com/java-syntax)
 - [Java ‘protected’ Access Modifier](https://www.baeldung.com/java-protected-access-modifier)
+- [Using the Not Operator in If Conditions in Java](https://www.baeldung.com/java-using-not-in-if-conditions)
 - [[<-- Prev]](/core-java-modules/core-java-lang-syntax)

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

@@ -13,4 +13,7 @@ This module contains articles about Java syntax
 - [Infinite Loops in Java](https://www.baeldung.com/infinite-loops-java)
 - [Java Switch Statement](https://www.baeldung.com/java-switch)
 - [Breaking Out of Nested Loops](https://www.baeldung.com/java-breaking-out-nested-loop)
+- [Java Do-While Loop](https://www.baeldung.com/java-do-while-loop)
+- [Java While Loop](https://www.baeldung.com/java-while-loop)
+- [Java For Loop](https://www.baeldung.com/java-for-loop)
 - [[More -->]](/core-java-modules/core-java-lang-syntax-2)

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

@@ -6,4 +6,5 @@
 - [Guide to Java Reflection](http://www.baeldung.com/java-reflection)
 - [Call Methods at Runtime Using Java Reflection](http://www.baeldung.com/java-method-reflection)
 - [Changing Annotation Parameters At Runtime](http://www.baeldung.com/java-reflection-change-annotation-params)
-- [Dynamic Proxies in Java](http://www.baeldung.com/java-dynamic-proxies)
+- [Dynamic Proxies in Java](http://www.baeldung.com/java-dynamic-proxies)
+- [What Causes java.lang.reflect.InvocationTargetException?](https://www.baeldung.com/java-lang-reflect-invocationtargetexception)

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

@@ -0,0 +1,10 @@
+=========
+
+## Core Java 8 Cookbooks and Examples
+
+### Relevant Articles: 
+- [An Overview of Regular Expressions Performance in Java](https://www.baeldung.com/java-regex-performance)
+- [A Guide To Java Regular Expressions API](http://www.baeldung.com/regular-expressions-java)
+- [Guide to Escaping Characters in Java RegExps](http://www.baeldung.com/java-regexp-escape-char)
+- [Pre-compile Regex Patterns Into Pattern Objects](https://www.baeldung.com/java-regex-pre-compile)
+- [Difference Between Java Matcher find() and matches()](https://www.baeldung.com/java-matcher-find-vs-matches)

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

@@ -2,9 +2,9 @@
 <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-text</artifactId>
+    <artifactId>core-java-regex</artifactId>
     <version>0.1.0-SNAPSHOT</version>
-    <name>core-java-text</name>
+    <name>core-java-regex</name>
     <packaging>jar</packaging>
 
     <parent>
@@ -28,7 +28,7 @@
     </dependencies>
 
     <build>
-        <finalName>core-java-text</finalName>
+        <finalName>core-java-regex</finalName>
         <resources>
             <resource>
                 <directory>src/main/resources</directory>

core-java-modules/core-java-regex/src/test/java/com/baeldung/regex/RegexUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.java.regex;
+package com.baeldung.regex;
 
 import static org.junit.Assert.*;
 

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

@@ -1,6 +0,0 @@
-=========
-
-## Core Java 8 Cookbooks and Examples
-
-### Relevant Articles: 
-- [An Overview of Regular Expressions Performance in Java](https://www.baeldung.com/java-regex-performance)

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

@@ -2,7 +2,6 @@
 
 ### Relevant Articles: 
 - [Java Timer](http://www.baeldung.com/java-timer-and-timertask)
-- [A Guide To Java Regular Expressions API](http://www.baeldung.com/regular-expressions-java)
 - [Getting Started with Java Properties](http://www.baeldung.com/java-properties)
 - [Introduction to Nashorn](http://www.baeldung.com/java-nashorn)
 - [Java Money and the Currency API](http://www.baeldung.com/java-money-and-currency)
@@ -11,7 +10,6 @@
 - [How to Get a Name of a Method Being Executed?](http://www.baeldung.com/java-name-of-executing-method)
 - [Introduction to Java Serialization](http://www.baeldung.com/java-serialization)
 - [Guide to UUID in Java](http://www.baeldung.com/java-uuid)
-- [Guide to Escaping Characters in Java RegExps](http://www.baeldung.com/java-regexp-escape-char)
 - [Creating a Java Compiler Plugin](http://www.baeldung.com/java-build-compiler-plugin)
 - [Quick Guide to Java Stack](http://www.baeldung.com/java-stack)
 - [Compiling Java *.class Files with javac](http://www.baeldung.com/javac)

core-java-modules/pom.xml

@@ -113,7 +113,7 @@
         <module>core-java-strings</module>
         <module>core-java-sun</module>
 
-        <module>core-java-text</module>
+        <module>core-java-regex</module>
         <!-- <module>core-java-time-measurements</module> --> <!-- We haven't upgraded to java 9. Fixing in BAEL-10841 -->
 
         <!-- <module>multimodulemavenproject</module> --> <!-- We haven't upgraded to java 9. Fixing in BAEL-10841 -->

core-kotlin-modules/core-kotlin-2/README.md

@@ -4,5 +4,5 @@ This module contains articles about Kotlin core features.
 
 ### Relevant articles:
 - [Working with Dates in Kotlin](https://www.baeldung.com/kotlin-dates)
-- [Kotlin Ternary Conditional Operator](https://www.baeldung.com/kotlin-ternary-conditional-operator)
+- [Kotlin Ternary Conditional Operator](https://www.baeldung.com/kotlin-ternary-operator)
 - [[<-- Prev]](/core-kotlin-modules/core-kotlin)

core-kotlin-modules/core-kotlin/README.md

@@ -3,7 +3,7 @@
 This module contains articles about Kotlin core features.
 
 ### Relevant articles:
-- [Introduction to the Kotlin Language](https://www.baeldung.com/kotlin)
+- [Introduction to the Kotlin Language](https://www.baeldung.com/kotlin-intro)
 - [Kotlin Java Interoperability](https://www.baeldung.com/kotlin-java-interoperability)
 - [Get a Random Number in Kotlin](https://www.baeldung.com/kotlin-random-number)
 - [Create a Java and Kotlin Project with Maven](https://www.baeldung.com/kotlin-maven-java-project)

data-structures/README.md

@@ -7,3 +7,5 @@ This module contains articles about data structures in Java
 - [The Trie Data Structure in Java](https://www.baeldung.com/trie-java)
 - [Implementing a Binary Tree in Java](https://www.baeldung.com/java-binary-tree)
 - [Circular Linked List Java Implementation](https://www.baeldung.com/java-circular-linked-list)
+- [How to Print a Binary Tree Diagram](https://www.baeldung.com/java-print-binary-tree-diagram)
+- [Introduction to Big Queue](https://www.baeldung.com/java-big-queue)

ddd/README.md

@@ -7,3 +7,4 @@ This module contains articles about Domain-driven Design (DDD)
 - [Persisting DDD Aggregates](https://www.baeldung.com/spring-persisting-ddd-aggregates)
 - [Double Dispatch in DDD](https://www.baeldung.com/ddd-double-dispatch)
 - [DDD Aggregates and @DomainEvents](https://www.baeldung.com/spring-data-ddd)
+- [Organizing Layers Using Hexagonal Architecture, DDD, and Spring](https://www.baeldung.com/hexagonal-architecture-ddd-spring)

dropwizard/README.md

@@ -1 +1,5 @@
-# Dropwizard
+# Dropwizard
+
+### Relevant Articles:
+
+- [Introduction to Dropwizard](https://www.baeldung.com/java-dropwizard)

image-processing/pom.xml

@@ -35,6 +35,11 @@
                 </exclusion>
             </exclusions>
         </dependency>
+        <dependency>
+            <groupId>org.openpnp</groupId>
+            <artifactId>opencv</artifactId>
+            <version>3.4.2-0</version>
+        </dependency>
         <dependency>
             <groupId>com.twelvemonkeys.imageio</groupId>
             <artifactId>imageio-core</artifactId>

image-processing/src/main/java/com/baeldung/imageprocessing/opencv/CameraStream.java

@@ -0,0 +1,87 @@
+package com.baeldung.imageprocessing.opencv;
+
+import javafx.animation.AnimationTimer;
+import javafx.application.Application;
+import javafx.scene.Scene;
+import javafx.scene.image.Image;
+import javafx.scene.image.ImageView;
+import javafx.scene.layout.HBox;
+import javafx.stage.Stage;
+import nu.pattern.OpenCV;
+import org.opencv.core.Mat;
+import org.opencv.core.MatOfByte;
+import org.opencv.core.MatOfRect;
+import org.opencv.core.Rect;
+import org.opencv.core.Scalar;
+import org.opencv.core.Size;
+import org.opencv.imgcodecs.Imgcodecs;
+import org.opencv.imgproc.Imgproc;
+import org.opencv.objdetect.CascadeClassifier;
+import org.opencv.objdetect.Objdetect;
+import org.opencv.videoio.VideoCapture;
+
+import java.io.ByteArrayInputStream;
+
+public class CameraStream extends Application {
+    private VideoCapture capture;
+
+    public void start(Stage stage) throws Exception {
+        OpenCV.loadShared();
+        capture=  new VideoCapture(0); // The number is the ID of the camera
+        ImageView imageView = new ImageView();
+        HBox hbox = new HBox(imageView);
+        Scene scene = new Scene(hbox);
+        stage.setScene(scene);
+        stage.show();
+        new AnimationTimer(){
+            @Override
+            public void handle(long l) {
+                imageView.setImage(getCapture());
+            }
+        }.start();
+    }
+
+    public Image getCapture() {
+        Mat mat = new Mat();
+        capture.read(mat);
+        return mat2Img(mat);
+    }
+
+    public Image getCaptureWithFaceDetection() {
+        Mat mat = new Mat();
+        capture.read(mat);
+        Mat haarClassifiedImg = detectFace(mat);
+        return mat2Img(haarClassifiedImg);
+    }
+
+    public Image mat2Img(Mat mat) {
+        MatOfByte bytes = new MatOfByte();
+        Imgcodecs.imencode("img", mat, bytes);
+        ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes.toArray());
+        Image img = new Image(inputStream); return img;
+    }
+
+    public static void main(String[] args) {
+        Application.launch(args);
+    }
+
+    public static Mat detectFace(Mat inputImage) {
+        MatOfRect facesDetected = new MatOfRect();
+        CascadeClassifier cascadeClassifier = new CascadeClassifier();
+        int minFaceSize = Math.round(inputImage.rows() * 0.1f);
+        cascadeClassifier.load("./src/main/resources/haarcascades/haarcascade_frontalface_alt.xml");
+        cascadeClassifier.detectMultiScale(inputImage,
+                facesDetected,
+                1.1,
+                3,
+                Objdetect.CASCADE_SCALE_IMAGE,
+                new Size(minFaceSize, minFaceSize),
+                new Size()
+        );
+        Rect[] facesArray =  facesDetected.toArray();
+        for(Rect face : facesArray) {
+            Imgproc.rectangle(inputImage, face.tl(), face.br(), new Scalar(0, 0, 255), 3 );
+        }
+        return inputImage;
+    }
+}

image-processing/src/main/java/com/baeldung/imageprocessing/opencv/FaceDetection.java

@@ -0,0 +1,56 @@
+package com.baeldung.imageprocessing.opencv;
+
+import org.opencv.core.Mat;
+import org.opencv.core.MatOfByte;
+import org.opencv.core.MatOfRect;
+import org.opencv.core.Rect;
+import org.opencv.core.Scalar;
+import org.opencv.core.Size;
+import org.opencv.imgcodecs.Imgcodecs;
+import org.opencv.imgproc.Imgproc;
+import org.opencv.objdetect.CascadeClassifier;
+import org.opencv.objdetect.Objdetect;
+import javafx.scene.image.Image;
+import java.io.ByteArrayInputStream;
+
+public class FaceDetection {
+
+    public static Mat loadImage(String imagePath) {
+        Imgcodecs imageCodecs = new Imgcodecs();
+        return imageCodecs.imread(imagePath);
+    }
+
+    public static void saveImage(Mat imageMatrix, String targetPath) {
+        Imgcodecs imgcodecs = new Imgcodecs();
+        imgcodecs.imwrite(targetPath, imageMatrix);
+    }
+
+    public static void detectFace(String sourceImagePath, String targetImagePath) {
+        Mat loadedImage = loadImage(sourceImagePath);
+        MatOfRect facesDetected = new MatOfRect();
+        CascadeClassifier cascadeClassifier = new CascadeClassifier();
+        int minFaceSize = Math.round(loadedImage.rows() * 0.1f);
+        cascadeClassifier.load("./src/main/resources/haarcascades/haarcascade_frontalface_alt.xml");
+        cascadeClassifier.detectMultiScale(loadedImage,
+                facesDetected,
+                1.1,
+                3,
+                Objdetect.CASCADE_SCALE_IMAGE,
+                new Size(minFaceSize, minFaceSize),
+                new Size()
+        );
+        Rect[] facesArray =  facesDetected.toArray();
+        for(Rect face : facesArray) {
+            Imgproc.rectangle(loadedImage, face.tl(), face.br(), new Scalar(0, 0, 255), 3 );
+        }
+        saveImage(loadedImage, targetImagePath);
+    }
+
+    public Image mat2Img(Mat mat) {
+        MatOfByte bytes = new MatOfByte();
+        Imgcodecs.imencode("img", mat, bytes);
+        ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes.toArray());
+        Image img = new Image(inputStream); return img;
+    }
+
+}

java-numbers-3/README.md

@@ -0,0 +1,4 @@
+### Relevant Articles:
+
+- [Generating Random Numbers](https://www.baeldung.com/java-generating-random-numbers)
+- [Convert Double to Long in Java](https://www.baeldung.com/java-convert-double-long)

json-2/README.md

@@ -3,3 +3,4 @@
 This module contains articles about JSON.
 
 ### Relevant Articles:
+- [Introduction to Jsoniter](https://www.baeldung.com/java-jsoniter)

libraries-2/src/test/java/com/baeldung/handlebars/BuiltinHelperUnitTest.java

@@ -1,15 +1,14 @@
 package com.baeldung.handlebars;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 import com.github.jknack.handlebars.Handlebars;
 import com.github.jknack.handlebars.Template;
 import com.github.jknack.handlebars.io.ClassPathTemplateLoader;
 import com.github.jknack.handlebars.io.TemplateLoader;
+import org.junit.Test;
+
 import java.io.IOException;
 
-import org.junit.Ignore;
-import org.junit.Test;
+import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * Showcases the built-in template helpers.
@@ -20,7 +19,6 @@ public class BuiltinHelperUnitTest {
 
     private TemplateLoader templateLoader = new ClassPathTemplateLoader("/handlebars", ".html");
 
-    @Ignore
     @Test
     public void whenUsedWith_ThenContextChanges() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -30,10 +28,9 @@ public class BuiltinHelperUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("\n<h4>I live in World</h4>\n");
+        assertThat(templateString).contains("<h4>I live in World</h4>");
     }
 
-    @Ignore
     @Test
     public void whenUsedWithMustacheStyle_ThenContextChanges() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -43,10 +40,9 @@ public class BuiltinHelperUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("\n<h4>I live in World</h4>\n");
+        assertThat(templateString).contains("<h4>I live in World</h4>");
     }
 
-    @Ignore
     @Test
     public void whenUsedEach_ThenIterates() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -59,11 +55,10 @@ public class BuiltinHelperUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("\n<span>Java is my friend.</span>\n"
-                                               + "\n<span>Spring is my friend.</span>\n");
+        assertThat(templateString)
+          .contains("<span>Java is my friend.</span>", "<span>Spring is my friend.</span>");
     }
 
-    @Ignore
     @Test
     public void whenUsedEachMustacheStyle_ThenIterates() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -76,11 +71,10 @@ public class BuiltinHelperUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("\n<span>Java is my friend.</span>\n"
-                                               + "\n<span>Spring is my friend.</span>\n");
+        assertThat(templateString)
+          .contains("<span>Java is my friend.</span>", "<span>Spring is my friend.</span>");
     }
 
-    @Ignore
     @Test
     public void whenUsedIf_ThenPutsCondition() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -90,10 +84,9 @@ public class BuiltinHelperUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("\n<h4>Baeldung is busy.</h4>\n");
+        assertThat(templateString).contains("<h4>Baeldung is busy.</h4>");
     }
 
-    @Ignore
     @Test
     public void whenUsedIfMustacheStyle_ThenPutsCondition() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -103,7 +96,7 @@ public class BuiltinHelperUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("\n<h4>Baeldung is busy.</h4>\n");
+        assertThat(templateString).contains("<h4>Baeldung is busy.</h4>");
     }
 
     private Person getPerson(String name) {

libraries-2/src/test/java/com/baeldung/handlebars/ReusingTemplatesUnitTest.java

@@ -1,15 +1,14 @@
 package com.baeldung.handlebars;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 import com.github.jknack.handlebars.Handlebars;
 import com.github.jknack.handlebars.Template;
 import com.github.jknack.handlebars.io.ClassPathTemplateLoader;
 import com.github.jknack.handlebars.io.TemplateLoader;
+import org.junit.Test;
+
 import java.io.IOException;
 
-import org.junit.Ignore;
-import org.junit.Test;
+import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * Showcases reusing the existing templates.
@@ -20,7 +19,6 @@ public class ReusingTemplatesUnitTest {
 
     private TemplateLoader templateLoader = new ClassPathTemplateLoader("/handlebars", ".html");
 
-    @Ignore
     @Test
     public void whenOtherTemplateIsReferenced_ThenCanReuse() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -30,10 +28,10 @@ public class ReusingTemplatesUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("<h4>Hi Baeldung!</h4>\n<p>This is the page Baeldung</p>");
+        assertThat(templateString)
+          .contains("<h4>Hi Baeldung!</h4>", "<p>This is the page Baeldung</p>");
     }
 
-    @Ignore
     @Test
     public void whenBlockIsDefined_ThenCanOverrideWithPartial() throws IOException {
         Handlebars handlebars = new Handlebars(templateLoader);
@@ -43,11 +41,11 @@ public class ReusingTemplatesUnitTest {
 
         String templateString = template.apply(person);
 
-        assertThat(templateString).isEqualTo("\n<html>\n"
-                                               + "<body>\n"
-                                               + "\n  This is the intro\n\n"
-                                               + "\n  Hi there!\n\n"
-                                               + "</body>\n"
-                                               + "</html>");
+        assertThat(templateString).contains("<html>",
+          "<body>",
+          "This is the intro",
+          "Hi there!",
+          "</body>",
+          "</html>");
     }
 }

libraries-3/README.md

@@ -9,3 +9,5 @@ Remember, for advanced libraries like [Jackson](/jackson) and [JUnit](/testing-m
 
 ### Relevant Articles:
 - [Parsing Command-Line Parameters with JCommander](https://www.baeldung.com/jcommander-parsing-command-line-parameters)
+- [Guide to the Cactoos Library](https://www.baeldung.com/java-cactoos)
+- [Parsing Command-Line Parameters with Airline](https://www.baeldung.com/java-airline)

libraries-3/pom.xml

@@ -24,7 +24,6 @@
             <artifactId>lombok</artifactId>
             <version>${lombok.version}</version>
         </dependency>
-
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>

libraries-data-io/src/test/java/com/baeldung/libraries/snakeyaml/MultiLineStringsUnitTest.java

@@ -0,0 +1,90 @@
+package com.baeldung.libraries.snakeyaml;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.yaml.snakeyaml.Yaml;
+
+import java.io.File;
+import java.io.InputStream;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+public class MultiLineStringsUnitTest {
+
+    private Yaml yaml;
+
+    @Before
+    public void setup() {
+        yaml = new Yaml();
+    }
+
+    @Test
+    public void whenLiteral_ThenLineBreaksArePresent() {
+        String key = parseYamlKey("literal.yaml", "key");
+        assertEquals("Line1\nLine2\nLine3", key);
+    }
+
+    @Test
+    public void whenLiteral_ThenEndingBreaksAreReducedToOne() {
+        String key = parseYamlKey("literal2.yaml", "key");
+        assertEquals("\n\nLine1\n\nLine2\n\nLine3\n", key);
+    }
+
+    @Test
+    public void whenFolded_ThenLineBreaksAreReplaced() {
+        String key = parseYamlKey("folded.yaml", "key");
+        assertEquals("Line1 Line2 Line3", key);
+    }
+
+    @Test
+    public void whenFolded_ThenEmptyLinesAreReducedToOne() {
+        String key = parseYamlKey("folded2.yaml", "key");
+        assertEquals("Line1 Line2\n\nLine3\n", key);
+    }
+
+    @Test
+    public void whenLiteralKeep_ThenLastEmptyLinesArePresent() {
+        String key = parseYamlKey("literal_keep.yaml", "key");
+        assertEquals("Line1\nLine2\nLine3\n\n", key);
+    }
+
+    @Test
+    public void whenLiteralStrip_ThenLastEmptyLinesAreRemoved() {
+        String key = parseYamlKey("literal_strip.yaml", "key");
+        assertEquals("Line1\nLine2\nLine3", key);
+    }
+
+    @Test
+    public void whenFoldedKeep_ThenLastEmptyLinesArePresent() {
+        String key = parseYamlKey("folded_keep.yaml", "key");
+        assertEquals("Line1 Line2 Line3\n\n\n", key);
+    }
+
+    @Test
+    public void whenFoldedStrip_ThenLastEmptyLinesAreRemoved() {
+        String key = parseYamlKey("folded_strip.yaml", "key");
+        assertEquals("Line1 Line2 Line3", key);
+    }
+
+    @Test
+    public void whenDoubleQuotes_ThenExplicitBreaksArePreserved() {
+        String key = parseYamlKey("plain_double_quotes.yaml", "key");
+        assertEquals("Line1\nLine2\nLine3", key);
+    }
+
+    @Test
+    public void whenSingleQuotes_ThenExplicitBreaksAreIgnored() {
+        String key = parseYamlKey("plain_single_quotes.yaml", "key");
+        assertEquals("Line1\\nLine2\nLine3", key);
+    }
+
+    String parseYamlKey(String fileName, String key) {
+        InputStream inputStream = this.getClass()
+                .getClassLoader()
+                .getResourceAsStream("yaml" + File.separator + "multiline" + File.separator + fileName);
+        Map<String, String> parsed = yaml.load(inputStream);
+        return parsed.get(key);
+    }
+
+}

libraries-data-io/src/test/resources/yaml/multiline/folded.yaml

@@ -0,0 +1,4 @@
+key: >
+  Line1
+  Line2
+  Line3

libraries-data-io/src/test/resources/yaml/multiline/folded2.yaml

@@ -0,0 +1,8 @@
+key: >
+  Line1
+  Line2
+
+
+  Line3
+
+

libraries-data-io/src/test/resources/yaml/multiline/folded_keep.yaml

@@ -0,0 +1,6 @@
+key: >+
+  Line1
+  Line2
+  Line3
+
+

libraries-data-io/src/test/resources/yaml/multiline/folded_strip.yaml

@@ -0,0 +1,7 @@
+key: >-
+  Line1
+  Line2
+  Line3
+
+
+

libraries-data-io/src/test/resources/yaml/multiline/literal.yaml

@@ -0,0 +1,4 @@
+key: |
+  Line1
+  Line2
+  Line3

libraries-data-io/src/test/resources/yaml/multiline/literal2.yaml

@@ -0,0 +1,10 @@
+key: |
+
+
+  Line1
+
+  Line2
+
+  Line3
+
+

libraries-data-io/src/test/resources/yaml/multiline/literal_keep.yaml

@@ -0,0 +1,5 @@
+key: |+
+  Line1
+  Line2
+  Line3
+

libraries-data-io/src/test/resources/yaml/multiline/literal_strip.yaml

@@ -0,0 +1,5 @@
+key: |-
+  Line1
+  Line2
+  Line3
+

libraries-data-io/src/test/resources/yaml/multiline/plain_double_quotes.yaml

@@ -0,0 +1 @@
+key: "Line1\nLine2\nLine3"

libraries-data-io/src/test/resources/yaml/multiline/plain_single_quotes.yaml

@@ -0,0 +1,3 @@
+key: 'Line1\nLine2
+
+  Line3'

libraries-http/README.md

@@ -13,3 +13,4 @@ This module contains articles about HTTP libraries.
 - [A Guide to Unirest](https://www.baeldung.com/unirest)
 - [Creating REST Microservices with Javalin](https://www.baeldung.com/javalin-rest-microservices)
 - [A Quick Guide to Timeouts in OkHttp](https://www.baeldung.com/okhttp-timeouts)
+- [A Quick Guide to Post Requests with OkHttp](https://www.baeldung.com/okhttp-post)

logging-modules/logback/README.md

@@ -2,3 +2,4 @@
 
 - [Get Log Output in JSON](https://www.baeldung.com/java-log-json-output)
 - [SLF4J Warning: Class Path Contains Multiple SLF4J Bindings](https://www.baeldung.com/slf4j-classpath-multiple-bindings)
+- [Sending Emails with Logback](https://www.baeldung.com/logback-send-email)

maven-all/maven/proxy/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Using Maven Behind a Proxy](https://www.baeldung.com/maven-behind-proxy)

ninja/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles
+
+- [Introduction to Ninja Framework](https://www.baeldung.com/ninja-framework-intro)

persistence-modules/hbase/README.md

@@ -1,3 +1,3 @@
 ### Relevant articles
 
-- [HBase with Java](http://www.baeldung.com/hbase)
+- [HBase with Java](https://www.baeldung.com/hbase)

persistence-modules/hbase/src/main/java/com/baeldung/hbase/HBaseClientOperations.java

@@ -1,4 +1,4 @@
-package org.baeldung.hbase;
+package com.baeldung.hbase;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HColumnDescriptor;

persistence-modules/hbase/src/main/java/com/baeldung/hbase/HbaseClientExample.java

@@ -1,4 +1,4 @@
-package org.baeldung.hbase;
+package com.baeldung.hbase;
 
 
 import com.google.protobuf.ServiceException;

persistence-modules/hibernate5-2/README.md

@@ -7,4 +7,5 @@ This module contains articles about Hibernate 5.
 - [FetchMode in Spring Data JPA](https://www.baeldung.com/spring-data-jpa-fetchmode)
 - [JPA/Hibernate Persistence Context](https://www.baeldung.com/jpa-hibernate-persistence-context)
 - [FetchMode in Hibernate](https://www.baeldung.com/hibernate-fetchmode)
+- [Various Logging Levels in Hibernate](https://www.baeldung.com/hibernate-logging-levels)
 - [[<-- Prev]](/hibernate5)

persistence-modules/java-mongodb/src/test/java/com/baeldung/aggregation/AggregationLiveTest.java

@@ -1,111 +1,111 @@
-package com.baeldung.aggregation;
-
-import static com.mongodb.client.model.Aggregates.count;
-import static com.mongodb.client.model.Aggregates.group;
-import static com.mongodb.client.model.Aggregates.limit;
-import static com.mongodb.client.model.Aggregates.match;
-import static com.mongodb.client.model.Aggregates.out;
-import static com.mongodb.client.model.Aggregates.project;
-import static com.mongodb.client.model.Aggregates.sort;
-import static org.junit.Assert.assertTrue;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.util.Arrays;
-
-import org.bson.Document;
-import org.bson.conversions.Bson;
-import org.junit.AfterClass;
-import org.junit.BeforeClass;
-import org.junit.Test;
-
-import com.mongodb.client.MongoClient;
-import com.mongodb.client.MongoClients;
-import com.mongodb.client.MongoCollection;
-import com.mongodb.client.MongoDatabase;
-import com.mongodb.client.model.Accumulators;
-import com.mongodb.client.model.Filters;
-import com.mongodb.client.model.Projections;
-import com.mongodb.client.model.Sorts;
-
-public class AggregationLiveTest {
-
-    private static final String DATABASE = "world";
-    private static final String COLLECTION = "countries";
-    private static final String DATASET_JSON = "/countrydata.json";
-    private static MongoClient mongoClient;
-    private static MongoDatabase database;
-    private static MongoCollection<Document> collection;
-
-    @BeforeClass
-    public static void setUpDB() throws IOException {
-        mongoClient = MongoClients.create();
-        database = mongoClient.getDatabase(DATABASE);
-        collection = database.getCollection(COLLECTION);
-
-        collection.drop();
-
-        InputStream is = AggregationLiveTest.class.getResourceAsStream(DATASET_JSON);
-        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
-        reader.lines()
-            .forEach(line -> collection.insertOne(Document.parse(line)));
-        reader.close();
-    }
-
-    @Test
-    public void givenCountryCollection_whenNAFTACountriesCounted_thenThree() {
-        Document naftaCountries = collection.aggregate(Arrays.asList(match(Filters.eq("regionalBlocs.acronym", "NAFTA")), count()))
-            .first();
-
-        assertEquals(3, naftaCountries.get("count"));
-    }
-
-    @Test
-    public void givenCountryCollection_whenAreaSortedDescending_thenSuccess() {
-
-        collection.aggregate(Arrays.asList(sort(Sorts.descending("area")), limit(7), out("largest_seven")))
-            .toCollection();
-
-        MongoCollection<Document> largestSeven = database.getCollection("largest_seven");
-
-        assertEquals(7, largestSeven.countDocuments());
-
-        Document usa = largestSeven.find(Filters.eq("alpha3Code", "USA"))
-            .first();
-
-        assertNotNull(usa);
-    }
-
-    @Test
-    public void givenCountryCollection_whenCountedRegionWise_thenMaxInAfrica() {
-        Document maxCountriedRegion = collection.aggregate(Arrays.asList(group("$region", Accumulators.sum("tally", 1)), sort(Sorts.descending("tally"))))
-            .first();
-        assertTrue(maxCountriedRegion.containsValue("Africa"));
-    }
-
-    @Test
-    public void givenCountryCollection_whenNeighborsCalculated_thenMaxIsFifteenInChina() {
-        Bson borderingCountriesCollection = project(Projections.fields(Projections.excludeId(), Projections.include("name"), Projections.computed("borderingCountries", Projections.computed("$size", "$borders"))));
-
-        int maxValue = collection.aggregate(Arrays.asList(borderingCountriesCollection, group(null, Accumulators.max("max", "$borderingCountries"))))
-            .first()
-            .getInteger("max");
-
-        assertEquals(15, maxValue);
-
-        Document maxNeighboredCountry = collection.aggregate(Arrays.asList(borderingCountriesCollection, match(Filters.eq("borderingCountries", maxValue))))
-            .first();
-        assertTrue(maxNeighboredCountry.containsValue("China"));
-
-    }
-
-    @AfterClass
-    public static void cleanUp() {
-        mongoClient.close();
-    }
-
-}
+package com.baeldung.aggregation;
+
+import static com.mongodb.client.model.Aggregates.count;
+import static com.mongodb.client.model.Aggregates.group;
+import static com.mongodb.client.model.Aggregates.limit;
+import static com.mongodb.client.model.Aggregates.match;
+import static com.mongodb.client.model.Aggregates.out;
+import static com.mongodb.client.model.Aggregates.project;
+import static com.mongodb.client.model.Aggregates.sort;
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+
+import org.bson.Document;
+import org.bson.conversions.Bson;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoDatabase;
+import com.mongodb.client.model.Accumulators;
+import com.mongodb.client.model.Filters;
+import com.mongodb.client.model.Projections;
+import com.mongodb.client.model.Sorts;
+
+public class AggregationLiveTest {
+
+    private static final String DATABASE = "world";
+    private static final String COLLECTION = "countries";
+    private static final String DATASET_JSON = "/countrydata.json";
+    private static MongoClient mongoClient;
+    private static MongoDatabase database;
+    private static MongoCollection<Document> collection;
+
+    @BeforeClass
+    public static void setUpDB() throws IOException {
+        mongoClient = MongoClients.create();
+        database = mongoClient.getDatabase(DATABASE);
+        collection = database.getCollection(COLLECTION);
+
+        collection.drop();
+
+        InputStream is = AggregationLiveTest.class.getResourceAsStream(DATASET_JSON);
+        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
+        reader.lines()
+            .forEach(line -> collection.insertOne(Document.parse(line)));
+        reader.close();
+    }
+
+    @Test
+    public void givenCountryCollection_whenEnglishSpeakingCountriesCounted_thenNinetyOne() {
+        Document englishSpeakingCountries = collection.aggregate(Arrays.asList(match(Filters.eq("languages.name", "English")), count()))
+            .first();
+
+        assertEquals(91, englishSpeakingCountries.get("count"));
+    }
+
+    @Test
+    public void givenCountryCollection_whenAreaSortedDescending_thenSuccess() {
+
+        collection.aggregate(Arrays.asList(sort(Sorts.descending("area")), limit(7), out("largest_seven")))
+            .toCollection();
+
+        MongoCollection<Document> largestSeven = database.getCollection("largest_seven");
+
+        assertEquals(7, largestSeven.countDocuments());
+
+        Document usa = largestSeven.find(Filters.eq("alpha3Code", "USA"))
+            .first();
+
+        assertNotNull(usa);
+    }
+
+    @Test
+    public void givenCountryCollection_whenCountedRegionWise_thenMaxInAfrica() {
+        Document maxCountriedRegion = collection.aggregate(Arrays.asList(group("$region", Accumulators.sum("tally", 1)), sort(Sorts.descending("tally"))))
+            .first();
+        assertTrue(maxCountriedRegion.containsValue("Africa"));
+    }
+
+    @Test
+    public void givenCountryCollection_whenNeighborsCalculated_thenMaxIsFifteenInChina() {
+        Bson borderingCountriesCollection = project(Projections.fields(Projections.excludeId(), Projections.include("name"), Projections.computed("borderingCountries", Projections.computed("$size", "$borders"))));
+
+        int maxValue = collection.aggregate(Arrays.asList(borderingCountriesCollection, group(null, Accumulators.max("max", "$borderingCountries"))))
+            .first()
+            .getInteger("max");
+
+        assertEquals(15, maxValue);
+
+        Document maxNeighboredCountry = collection.aggregate(Arrays.asList(borderingCountriesCollection, match(Filters.eq("borderingCountries", maxValue))))
+            .first();
+        assertTrue(maxNeighboredCountry.containsValue("China"));
+
+    }
+
+    @AfterClass
+    public static void cleanUp() {
+        mongoClient.close();
+    }
+
+}

persistence-modules/querydsl/README.md

@@ -1,3 +1,3 @@
 ### Relevant Articles:
-- [Intro to Querydsl](http://www.baeldung.com/intro-to-querydsl)
-- [A Guide to Querydsl with JPA](http://www.baeldung.com/querydsl-with-jpa-tutorial)
+- [Intro to Querydsl](https://www.baeldung.com/intro-to-querydsl)
+- [A Guide to Querydsl with JPA](https://www.baeldung.com/querydsl-with-jpa-tutorial)

persistence-modules/querydsl/src/main/java/com/baeldung/dao/PersonDao.java

@@ -1,9 +1,9 @@
-package org.baeldung.dao;
+package com.baeldung.dao;
 
 import java.util.List;
 import java.util.Map;
 
-import org.baeldung.entity.Person;
+import com.baeldung.entity.Person;
 
 public interface PersonDao {
 

persistence-modules/querydsl/src/main/java/com/baeldung/dao/PersonDaoImpl.java

@@ -1,17 +1,15 @@
-package org.baeldung.dao;
+package com.baeldung.dao;
 
-import java.util.List;
-import java.util.Map;
+import com.baeldung.entity.Person;
+import com.baeldung.entity.QPerson;
+import com.querydsl.core.group.GroupBy;
+import com.querydsl.jpa.impl.JPAQuery;
+import org.springframework.stereotype.Repository;
 
 import javax.persistence.EntityManager;
 import javax.persistence.PersistenceContext;
-
-import org.baeldung.entity.Person;
-import org.baeldung.entity.QPerson;
-import org.springframework.stereotype.Repository;
-
-import com.querydsl.core.group.GroupBy;
-import com.querydsl.jpa.impl.JPAQuery;
+import java.util.List;
+import java.util.Map;
 
 @Repository
 public class PersonDaoImpl implements PersonDao {

persistence-modules/querydsl/src/main/java/com/baeldung/entity/Person.java

@@ -1,4 +1,4 @@
-package org.baeldung.entity;
+package com.baeldung.entity;
 
 import javax.persistence.Column;
 import javax.persistence.Entity;

persistence-modules/querydsl/src/main/java/com/baeldung/querydsl/intro/entities/BlogPost.java

@@ -1,7 +1,7 @@
 /*
  * (c) Центр ИТ, 2016. Все права защищены.
  */
-package org.baeldung.querydsl.intro.entities;
+package com.baeldung.querydsl.intro.entities;
 
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;

persistence-modules/querydsl/src/main/java/com/baeldung/querydsl/intro/entities/User.java

@@ -1,7 +1,7 @@
 /*
  * (c) Центр ИТ, 2016. Все права защищены.
  */
-package org.baeldung.querydsl.intro.entities;
+package com.baeldung.querydsl.intro.entities;
 
 import java.util.HashSet;
 import java.util.Set;

persistence-modules/querydsl/src/main/resources/META-INF/persistence.xml

@@ -17,7 +17,7 @@
     </persistence-unit>
 
     <!-- PersistenceUnit for Intro to QueryDSL -->
-    <persistence-unit name="org.baeldung.querydsl.intro">
+    <persistence-unit name="com.baeldung.querydsl.intro">
         <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
         <properties>
             <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>

persistence-modules/querydsl/src/test/java/com/baeldung/dao/PersonDaoIntegrationTest.java

@@ -1,8 +1,8 @@
-package org.baeldung.dao;
+package com.baeldung.dao;
 
 import java.util.Map;
 
-import org.baeldung.entity.Person;
+import com.baeldung.entity.Person;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;

persistence-modules/querydsl/src/test/java/com/baeldung/querydsl/intro/QueryDSLIntegrationTest.java

@@ -1,17 +1,17 @@
 /*
  * (c) Центр ИТ, 2016. Все права защищены.
  */
-package org.baeldung.querydsl.intro;
+package com.baeldung.querydsl.intro;
 
+import com.baeldung.querydsl.intro.entities.BlogPost;
+import com.baeldung.querydsl.intro.entities.QBlogPost;
+import com.baeldung.querydsl.intro.entities.QUser;
+import com.baeldung.querydsl.intro.entities.User;
 import com.querydsl.core.Tuple;
 import com.querydsl.core.types.dsl.Expressions;
 import com.querydsl.core.types.dsl.NumberPath;
 import com.querydsl.jpa.JPAExpressions;
 import com.querydsl.jpa.impl.JPAQueryFactory;
-import org.baeldung.querydsl.intro.entities.BlogPost;
-import org.baeldung.querydsl.intro.entities.QBlogPost;
-import org.baeldung.querydsl.intro.entities.QUser;
-import org.baeldung.querydsl.intro.entities.User;
 import org.junit.*;
 
 import javax.persistence.EntityManager;
@@ -31,7 +31,7 @@ public class QueryDSLIntegrationTest {
 
     @BeforeClass
     public static void populateDatabase() {
-        emf = Persistence.createEntityManagerFactory("org.baeldung.querydsl.intro");
+        emf = Persistence.createEntityManagerFactory("com.baeldung.querydsl.intro");
         EntityManager em = emf.createEntityManager();
 
         em.getTransaction().begin();

persistence-modules/querydsl/src/test/resources/test-context.xml

@@ -13,7 +13,7 @@
         >
 
     <tx:annotation-driven />
-    <context:component-scan base-package="org.baeldung" />
+    <context:component-scan base-package="com.baeldung" />
 
     <import resource="test-db.xml" />
 

persistence-modules/r2dbc/pom.xml

@@ -3,7 +3,7 @@
          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>org.baeldung.examples.r2dbc</groupId>
+    <groupId>com.baeldung.examples.r2dbc</groupId>
     <artifactId>r2dbc-example</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <name>r2dbc-example</name>

persistence-modules/r2dbc/src/main/java/com/baeldung/examples/r2dbc/Account.java

@@ -1,4 +1,4 @@
-package org.baeldung.examples.r2dbc;
+package com.baeldung.examples.r2dbc;
 
 import java.math.BigDecimal;
 

persistence-modules/r2dbc/src/main/java/com/baeldung/examples/r2dbc/AccountResource.java

@@ -1,12 +1,8 @@
 /**
  * 
  */
-package org.baeldung.examples.r2dbc;
+package com.baeldung.examples.r2dbc;
 
-import java.math.BigDecimal;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -15,8 +11,6 @@ import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RestController;
 
-import io.r2dbc.spi.Connection;
-import io.r2dbc.spi.ConnectionFactory;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 

persistence-modules/r2dbc/src/main/java/com/baeldung/examples/r2dbc/DatasourceConfig.java

@@ -1,16 +1,14 @@
-package org.baeldung.examples.r2dbc;
+package com.baeldung.examples.r2dbc;
 
 import org.springframework.boot.CommandLineRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.util.StringUtils;
 
 import io.netty.util.internal.StringUtil;
 import io.r2dbc.spi.ConnectionFactories;
 import io.r2dbc.spi.ConnectionFactory;
 import io.r2dbc.spi.ConnectionFactoryOptions;
 import io.r2dbc.spi.ConnectionFactoryOptions.Builder;
-import io.r2dbc.spi.Option;
 import reactor.core.publisher.Flux;
 
 import static io.r2dbc.spi.ConnectionFactoryOptions.*;

persistence-modules/r2dbc/src/main/java/com/baeldung/examples/r2dbc/R2DBCConfigurationProperties.java

@@ -1,4 +1,4 @@
-package org.baeldung.examples.r2dbc;
+package com.baeldung.examples.r2dbc;
 
 import javax.validation.constraints.NotEmpty;
 

persistence-modules/r2dbc/src/main/java/com/baeldung/examples/r2dbc/R2dbcExampleApplication.java

@@ -1,4 +1,4 @@
-package org.baeldung.examples.r2dbc;
+package com.baeldung.examples.r2dbc;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;

persistence-modules/r2dbc/src/main/java/com/baeldung/examples/r2dbc/ReactiveAccountDao.java

@@ -1,9 +1,7 @@
-package org.baeldung.examples.r2dbc;
+package com.baeldung.examples.r2dbc;
 
 import java.math.BigDecimal;
 
-import org.springframework.http.HttpStatus;
-import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Component;
 
 import io.r2dbc.spi.Connection;

persistence-modules/r2dbc/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -1,5 +1,5 @@
 {"properties": [{
   "name": "r2dbc",
-  "type": "org.baeldung.examples.r2dbc.R2DBCConfigurationProperties",
+  "type": "com.baeldung.examples.r2dbc.R2DBCConfigurationProperties",
   "description": "R2DBC Connection properties"
 }]}

persistence-modules/r2dbc/src/test/java/com/baeldung/examples/r2dbc/R2dbcExampleApplicationTests.java

@@ -1,19 +1,15 @@
-package org.baeldung.examples.r2dbc;
+package com.baeldung.examples.r2dbc;
 
 import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 
 import java.util.List;
 
-import org.hamcrest.core.IsNull;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.CommandLineRunner;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
 import org.springframework.http.MediaType;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.test.web.reactive.server.WebTestClient;

persistence-modules/redis/README.md

@@ -2,3 +2,4 @@
 - [Intro to Jedis – the Java Redis Client Library](http://www.baeldung.com/jedis-java-redis-client-library)
 - [A Guide to Redis with Redisson](http://www.baeldung.com/redis-redisson)
 - [Introduction to Lettuce – the Java Redis Client](https://www.baeldung.com/java-redis-lettuce)
+- [List All Available Redis Keys](https://www.baeldung.com/redis-list-available-keys)

persistence-modules/redis/src/main/java/com/baeldung/redis_scan/client/RedisClient.java

@@ -145,5 +145,10 @@ public class RedisClient {
             log.error("Exception caught in flushAll", ex);
         }
     }
+    
+    public void destroyInstance() {
+        jedisPool = null;
+        instance = null;
+    }
 
 }

persistence-modules/redis/src/test/java/com/baeldung/redis_scan/NaiveApproachIntegrationTest.java

@@ -25,13 +25,14 @@ public class NaiveApproachIntegrationTest {
         s.close();
 
         redisServer = new RedisServer(port);
-        redisServer.start();
     }
 
     @AfterClass
     public static void destroy() {
-        if (redisServer.isActive())
+        if (redisServer.isActive()) {
             redisServer.stop();
+            redisClient.destroyInstance();
+        }
     }
 
     @Before