Merge branch 'master' into BAEL-3758_AOP_Annotations_jcabi-aspects

akka-http/src/test/java/com/baeldung/akkahttp/UserServerUnitTest.java

@@ -31,10 +31,10 @@ public class UserServerUnitTest extends JUnitRouteTest {
             .assertStatusCode(404);
 
     appRoute.run(HttpRequest.DELETE("/users/1"))
-            .assertStatusCode(200);
+            .assertStatusCode(405);
 
     appRoute.run(HttpRequest.DELETE("/users/42"))
-            .assertStatusCode(200);
+            .assertStatusCode(405);
 
     appRoute.run(HttpRequest.POST("/users")
             .withEntity(HttpEntities.create(ContentTypes.APPLICATION_JSON, zaphod())))

algorithms-miscellaneous-2/README.md

@@ -13,4 +13,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Create a Sudoku Solver in Java](https://www.baeldung.com/java-sudoku)
 - [Displaying Money Amounts in Words](https://www.baeldung.com/java-money-into-words)
 - [A Collaborative Filtering Recommendation System in Java](https://www.baeldung.com/java-collaborative-filtering-recommendations)
+- [Implementing A* Pathfinding in Java](https://www.baeldung.com/java-a-star-pathfinding)
 - More articles: [[<-- prev]](/../algorithms-miscellaneous-1) [[next -->]](/../algorithms-miscellaneous-3)

algorithms-miscellaneous-2/src/main/java/com/baeldung/algorithms/slope_one/SlopeOne.java

@@ -98,7 +98,7 @@ public class SlopeOne {
             for (Item j : InputData.items) {
                 if (e.getValue().containsKey(j)) {
                     clean.put(j, e.getValue().get(j));
-                } else {
+                } else if (!clean.containsKey(j)) {
                     clean.put(j, -1.0);
                 }
             }

algorithms-miscellaneous-5/README.md

@@ -12,4 +12,8 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [How to Determine if a Binary Tree is Balanced](https://www.baeldung.com/java-balanced-binary-tree)
 - [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)
 - 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/main/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingDeque.java

@@ -0,0 +1,36 @@
+package com.baeldung.algorithms.balancedbrackets;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+public class BalancedBracketsUsingDeque {
+
+    public boolean isBalanced(String str) {
+        if (null == str || ((str.length() % 2) != 0)) {
+            return false;
+        } else {
+            char[] ch = str.toCharArray();
+            for (char c : ch) {
+                if (!(c == '{' || c == '[' || c == '(' || c == '}' || c == ']' || c == ')')) {
+                    return false;
+                }
+
+            }
+        }
+
+        Deque<Character> deque = new LinkedList<>();
+        for (char ch : str.toCharArray()) {
+            if (ch == '{' || ch == '[' || ch == '(') {
+                deque.addFirst(ch);
+            } else {
+                if (!deque.isEmpty() && ((deque.peekFirst() == '{' && ch == '}') || (deque.peekFirst() == '[' && ch == ']') || (deque.peekFirst() == '(' && ch == ')'))) {
+                    deque.removeFirst();
+                } else {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+}

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingString.java

@@ -0,0 +1,27 @@
+package com.baeldung.algorithms.balancedbrackets;
+
+public class BalancedBracketsUsingString {
+
+    public boolean isBalanced(String str) {
+        if (null == str || ((str.length() % 2) != 0)) {
+            return false;
+        } else {
+            char[] ch = str.toCharArray();
+            for (char c : ch) {
+                if (!(c == '{' || c == '[' || c == '(' || c == '}' || c == ']' || c == ')')) {
+                    return false;
+                }
+
+            }
+        }
+
+        while (str.contains("()") || str.contains("[]") || str.contains("{}")) {
+            str = str.replaceAll("\\(\\)", "")
+                .replaceAll("\\[\\]", "")
+                .replaceAll("\\{\\}", "");
+        }
+        return (str.length() == 0);
+
+    }
+
+}

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-miscellaneous-5/src/test/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingDequeUnitTest.java

@@ -0,0 +1,76 @@
+package com.baeldung.algorithms.balancedbrackets;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class BalancedBracketsUsingDequeUnitTest {
+    private BalancedBracketsUsingDeque balancedBracketsUsingDeque;
+
+    @Before
+    public void setup() {
+        balancedBracketsUsingDeque = new BalancedBracketsUsingDeque();
+    }
+
+    @Test
+    public void givenNullInput_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced(null);
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEmptyString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenInvalidCharacterString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("abc[](){}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenOddLengthString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{{[]()}}}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEvenLengthString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{{[]()}}}}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEvenLengthUnbalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{[(])}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEvenLengthBalancedString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{[()]}");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenBalancedString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{{[[(())]]}}");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenAnotherBalancedString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{{([])}}");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenUnBalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingDeque.isBalanced("{{)[](}}");
+        assertThat(result).isFalse();
+    }
+
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/balancedbrackets/BalancedBracketsUsingStringUnitTest.java

@@ -0,0 +1,76 @@
+package com.baeldung.algorithms.balancedbrackets;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class BalancedBracketsUsingStringUnitTest {
+    private BalancedBracketsUsingString balancedBracketsUsingString;
+
+    @Before
+    public void setup() {
+        balancedBracketsUsingString = new BalancedBracketsUsingString();
+    }
+
+    @Test
+    public void givenNullInput_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced(null);
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEmptyString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingString.isBalanced("");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenInvalidCharacterString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced("abc[](){}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenOddLengthString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced("{{[]()}}}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEvenLengthString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced("{{[]()}}}}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEvenLengthUnbalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced("{[(])}");
+        assertThat(result).isFalse();
+    }
+
+    @Test
+    public void givenEvenLengthBalancedString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingString.isBalanced("{[()]}");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenBalancedString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingString.isBalanced("{{[[(())]]}}");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenAnotherBalancedString_whenCheckingForBalance_shouldReturnTrue() {
+        boolean result = balancedBracketsUsingString.isBalanced("{{([])}}");
+        assertThat(result).isTrue();
+    }
+
+    @Test
+    public void givenUnBalancedString_whenCheckingForBalance_shouldReturnFalse() {
+        boolean result = balancedBracketsUsingString.isBalanced("{{)[](}}");
+        assertThat(result).isFalse();
+    }
+
+}

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

@@ -0,0 +1,53 @@
+package com.baeldung.poi.excel;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.util.CellRangeAddress;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ExcelCellMergerUnitTest {
+    private static final String FILE_NAME = "ExcelCellFormatterTest.xlsx";
+    private String fileLocation;
+
+    @Before
+    public void setup() throws IOException, URISyntaxException {
+            fileLocation = Paths.get(ClassLoader.getSystemResource(FILE_NAME).toURI()).toString();
+    }
+
+    @Test
+    public void givenCellIndex_whenAddMergeRegion_thenMergeRegionCreated() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+
+        assertEquals(0, sheet.getNumMergedRegions());
+        int firstRow = 0; 
+        int lastRow = 0; 
+        int firstCol = 0; 
+        int lastCol = 2;
+        sheet.addMergedRegion(new CellRangeAddress(firstRow, lastRow, firstCol, lastCol));
+        assertEquals(1, sheet.getNumMergedRegions());
+
+        workbook.close();
+    }
+
+    @Test
+    public void givenCellRefString_whenAddMergeRegion_thenMergeRegionCreated() throws IOException {
+        Workbook workbook = new XSSFWorkbook(fileLocation);
+        Sheet sheet = workbook.getSheetAt(0);
+
+        assertEquals(0, sheet.getNumMergedRegions());        
+        sheet.addMergedRegion(CellRangeAddress.valueOf("A1:C1"));
+        assertEquals(1, sheet.getNumMergedRegions());
+
+        workbook.close();
+    }
+
+}

apache-spark/README.md

@@ -7,4 +7,4 @@ This module contains articles about Apache Spark
 - [Introduction to Apache Spark](https://www.baeldung.com/apache-spark)
 - [Building a Data Pipeline with Kafka, Spark Streaming and Cassandra](https://www.baeldung.com/kafka-spark-data-pipeline)
 - [Machine Learning with Spark MLlib](https://www.baeldung.com/spark-mlib-machine-learning)
-
+- [Introduction to Spark Graph Processing with GraphFrames](https://www.baeldung.com/spark-graph-graphframes)

apache-tapestry/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles
+
+- [Intro to Apache Tapestry](https://www.baeldung.com/apache-tapestry)

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-groovy-2/pom.xml

@@ -77,7 +77,7 @@
                     <dependency>
                         <groupId>org.codehaus.groovy</groupId>
                         <artifactId>groovy-eclipse-compiler</artifactId>
-                        <version>3.3.0-01</version>
+                        <version>${groovy.compiler.version}</version>
                     </dependency>
                     <dependency>
                         <groupId>org.codehaus.groovy</groupId>

core-groovy-2/src/test/groovy/com/baeldung/category/CategoryUnitTest.groovy

@@ -28,17 +28,16 @@ class CategoryUnitTest extends GroovyTestCase {
         }
     }
 
-//	http://team.baeldung.com/browse/BAEL-20687
-//    void test_whenUsingTimeCategory_thenOperationOnNumber() {
-//        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy")
-//        use (TimeCategory) {
-//            assert sdf.format(5.days.from.now) == sdf.format(new Date() + 5.days)
-//
-//            sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss")
-//            assert sdf.format(10.minutes.from.now) == sdf.format(new Date() + 10.minutes)
-//            assert sdf.format(2.hours.ago) == sdf.format(new Date() - 2.hours)
-//        }
-//    }
+    void test_whenUsingTimeCategory_thenOperationOnNumber() {
+        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy")
+        use (TimeCategory) {
+            assert sdf.format(5.days.from.now) == sdf.format(new Date() + 5.days)
+
+            sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss")
+            assert sdf.format(10.minutes.from.now) == sdf.format(new Date() + 10.minutes)
+            assert sdf.format(2.hours.ago) == sdf.format(new Date() - 2.hours)
+        }
+    }
 
     void test_whenUsingDOMCategory_thenOperationOnXML() {
 

core-groovy-2/src/test/groovy/com/baeldung/webservice/WebserviceUnitTest.groovy

@@ -75,7 +75,6 @@ class WebserviceManualTest extends GroovyTestCase {
         assert stories.size() == 5
     }
     
-    /* see BAEL-3753
     void test_whenConsumingSoap_thenReceiveResponse() {
         def url = "http://www.dataaccess.com/webservicesserver/numberconversion.wso"
         def soapClient = new SOAPClient(url)
@@ -90,7 +89,6 @@ class WebserviceManualTest extends GroovyTestCase {
         def words = response.NumberToWordsResponse
         assert words == "one thousand two hundred and thirty four "
     }
-    */
 
     void test_whenConsumingRestGet_thenReceiveResponse() {
         def path = "/get"

core-groovy/src/test/groovy/com/baeldung/file/ReadFileUnitTest.groovy

@@ -33,7 +33,6 @@ class ReadFileUnitTest extends Specification {
             assert lines.size(), 3
     }
     
-    @Ignore
     def 'Should return file content in string using ReadFile.readFileString given filePath' () {
         given:
             def filePath = "src/main/resources/fileContent.txt"

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-11/pom.xml

@@ -65,7 +65,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
-                <version>3.2.1</version>
+                <version>${shade.plugin.version}</version>
                 <executions>
                     <execution>
                         <phase>package</phase>
@@ -109,6 +109,7 @@
         <uberjar.name>benchmarks</uberjar.name>
         <jmh.version>1.22</jmh.version>
         <eclipse.collections.version>10.0.0</eclipse.collections.version>
+        <shade.plugin.version>10.0.0</shade.plugin.version>
     </properties>
 
 </project>

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

@@ -0,0 +1,3 @@
+### Relevant articles:
+
+- [Java Switch Statement](https://www.baeldung.com/java-switch)

core-java-modules/core-java-14/.mvn/jvm.config

@@ -0,0 +1 @@
+--enable-preview

core-java-modules/core-java-14/README.md

@@ -0,0 +1,7 @@
+## Core Java 14
+
+This module contains articles about Java 14. 
+
+### Relevant articles
+
+- [Guide to the @Serial Annotation in Java 14](https://www.baeldung.com/java-14-serial-annotation)

core-java-modules/core-java-14/pom.xml

@@ -1,53 +1,66 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-	<modelVersion>4.0.0</modelVersion>
-	<groupId>com.baeldung</groupId>
-	<artifactId>core-java-14</artifactId>
-	<version>1.0.0-SNAPSHOT</version>
-	<name>core-java-14</name>
-	<packaging>jar</packaging>
-	<url>http://maven.apache.org</url>
+         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-14</artifactId>
+    <name>core-java-14</name>
+    <packaging>jar</packaging>
+    <url>http://maven.apache.org</url>
 
-	<parent>
-		<groupId>com.baeldung</groupId>
-		<artifactId>parent-modules</artifactId>
-		<version>1.0.0-SNAPSHOT</version>
-		<relativePath>../../</relativePath>
-	</parent>
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../../</relativePath>
+    </parent>
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>${junit-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <release>${maven.compiler.release}</release>
+                    <compilerArgs>--enable-preview</compilerArgs>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${surefire.plugin.version}</version>
+                <configuration>
+                    <argLine>--enable-preview</argLine>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 
-	<build>
-		<plugins>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-compiler-plugin</artifactId>
-				<version>${maven-compiler-plugin.version}</version>
-				<configuration>
-					<source>${maven.compiler.source.version}</source>
-					<target>${maven.compiler.target.version}</target>
-					<compilerArgs>
-						<compilerArg>
-							--enable-preview
-						</compilerArg>
-					</compilerArgs>
-				</configuration>
-			</plugin>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-surefire-plugin</artifactId>
-				<version>${surefire.plugin.version}</version>
-				<configuration>
-					<argLine>--enable-preview</argLine>
-				</configuration>
-			</plugin>
-		</plugins>
-	</build>
-
-	<properties>
-		<maven.compiler.source.version>14</maven.compiler.source.version>
-		<maven.compiler.target.version>14</maven.compiler.target.version>
+    <properties>
+        <maven.compiler.release>14</maven.compiler.release>
+        <assertj.version>3.6.1</assertj.version>
+        <maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
         <surefire.plugin.version>3.0.0-M3</surefire.plugin.version>
-	</properties>
+    </properties>
 
 </project>

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/textblocks/TextBlocks13.java

@@ -0,0 +1,46 @@
+package com.baeldung.java14.textblocks;
+
+public class TextBlocks13 {
+    public String getBlockOfHtml() {
+        return """
+            <html>
+
+                <body>
+                    <span>example text</span>
+                </body>
+            </html>""";
+    }
+
+    public String getNonStandardIndent() {
+        return """
+                Indent
+            """;
+    }
+
+    public String getQuery() {
+        return """
+            select "id", "user"
+            from "table"
+            """;
+    }
+
+    public String getTextWithCarriageReturns() {
+        return """
+            separated with\r
+            carriage returns""";
+    }
+
+    public String getTextWithEscapes() {
+        return """
+            fun with\n
+            whitespace\t\r
+            and other escapes \"""
+            """;
+    }
+
+    public String getFormattedText(String parameter) {
+        return """
+            Some parameter: %s
+            """.formatted(parameter);
+    }
+}

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/textblocks/TextBlocks14.java

@@ -0,0 +1,16 @@
+package com.baeldung.java14.textblocks;
+
+public class TextBlocks14 {
+    public String getIgnoredNewLines() {
+        return """
+            This is a long test which looks to \
+            have a newline but actually does not""";
+    }
+
+    public String getEscapedSpaces() {
+        return """
+            line 1
+            line 2       \s
+            """;
+    }
+}

core-java-modules/core-java-14/src/main/java/com/baeldung/serial/MySerialClass.java

@@ -10,41 +10,41 @@ import java.io.Serializable;
 
 /**
  * Class showcasing the usage of the Java 14 @Serial annotation.
- * 
+ *
  * @author Donato Rimenti
  */
 public class MySerialClass implements Serializable {
-	
-	@Serial
-	private static final ObjectStreamField[] serialPersistentFields = null;
-	
-	@Serial
-	private static final long serialVersionUID = 1;
 
-	@Serial
-	private void writeObject(ObjectOutputStream stream) throws IOException {
-		// ...
-	}
+    @Serial
+    private static final ObjectStreamField[] serialPersistentFields = null;
 
-	@Serial
-	private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
-		// ...
-	}
+    @Serial
+    private static final long serialVersionUID = 1;
 
-	@Serial
-	private void readObjectNoData() throws ObjectStreamException {
-		// ...
-	}
+    @Serial
+    private void writeObject(ObjectOutputStream stream) throws IOException {
+        // ...
+    }
 
-	@Serial
-	private Object writeReplace() throws ObjectStreamException {
-		// ...
-		return null;
-	}
+    @Serial
+    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
+        // ...
+    }
 
-	@Serial
-	private Object readResolve() throws ObjectStreamException {
-		// ...
-		return null;
-	}
+    @Serial
+    private void readObjectNoData() throws ObjectStreamException {
+        // ...
+    }
+
+    @Serial
+    private Object writeReplace() throws ObjectStreamException {
+        // ...
+        return null;
+    }
+
+    @Serial
+    private Object readResolve() throws ObjectStreamException {
+        // ...
+        return null;
+    }
 }

core-java-modules/core-java-14/src/test/java/com/baeldung/java14/textblocks/TextBlocks13UnitTest.java

@@ -0,0 +1,58 @@
+package com.baeldung.java14.textblocks;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class TextBlocks13UnitTest {
+    private TextBlocks13 subject = new TextBlocks13();
+
+    @Test
+    void givenAnOldStyleMultilineString_whenComparing_thenEqualsTextBlock() {
+        String expected = "<html>\n"
+          + "\n"
+          + "    <body>\n"
+          + "        <span>example text</span>\n"
+          + "    </body>\n"
+          + "</html>";
+        assertThat(subject.getBlockOfHtml()).isEqualTo(expected);
+    }
+
+    @Test
+    void givenAnOldStyleString_whenComparing_thenEqualsTextBlock() {
+        String expected = "<html>\n\n    <body>\n        <span>example text</span>\n    </body>\n</html>";
+        assertThat(subject.getBlockOfHtml()).isEqualTo(expected);
+    }
+
+    @Test
+    void givenAnIndentedString_thenMatchesIndentedOldStyle() {
+        assertThat(subject.getNonStandardIndent()).isEqualTo("    Indent\n");
+    }
+
+    @Test
+    void givenAMultilineQuery_thenItCanContainUnescapedQuotes() {
+        assertThat(subject.getQuery()).contains("select \"id\", \"user\"");
+    }
+
+    @Test
+    void givenAMultilineQuery_thenItEndWithANewline() {
+        assertThat(subject.getQuery()).endsWith("\n");
+    }
+
+    @Test
+    void givenATextWithCarriageReturns_thenItContainsBoth() {
+        assertThat(subject.getTextWithCarriageReturns()).isEqualTo("separated with\r\ncarriage returns");
+    }
+
+    @Test
+    void givenAStringWithEscapedWhitespace_thenItAppearsInTheResultingString() {
+        assertThat(subject.getTextWithEscapes()).contains("fun with\n\n")
+            .contains("whitespace\t\r\n")
+            .contains("and other escapes \"\"\"");
+    }
+
+    @Test
+    void givenAFormattedString_thenTheParameterIsReplaced() {
+        assertThat(subject.getFormattedText("parameter")).contains("Some parameter: parameter");
+    }
+}

core-java-modules/core-java-14/src/test/java/com/baeldung/java14/textblocks/TextBlocks14UnitTest.java

@@ -0,0 +1,21 @@
+package com.baeldung.java14.textblocks;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class TextBlocks14UnitTest {
+    private TextBlocks14 subject = new TextBlocks14();
+
+    @Test
+    void givenAStringWithEscapedNewLines_thenTheResultHasNoNewLines() {
+        String expected = "This is a long test which looks to have a newline but actually does not";
+        assertThat(subject.getIgnoredNewLines()).isEqualTo(expected);
+    }
+
+    @Test
+    void givenAStringWithEscapesSpaces_thenTheResultHasLinesEndingWithSpaces() {
+        String expected = "line 1\nline 2        \n";
+        assertThat(subject.getEscapedSpaces()).isEqualTo(expected);
+    }
+}

core-java-modules/core-java-8/pom.xml

@@ -61,7 +61,7 @@
                         </goals>
                         <configuration>
                             <classifier>spring-boot</classifier>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </configuration>
                     </execution>
                 </executions>

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

@@ -9,6 +9,7 @@ This module contains articles about Java 9 core features
 - [Iterate Through a Range of Dates in Java](https://www.baeldung.com/java-iterate-date-range)
 - [Initialize a HashMap in Java](https://www.baeldung.com/java-initialize-hashmap)
 - [Immutable Set in Java](https://www.baeldung.com/java-immutable-set)
+- [Immutable ArrayList in Java](https://www.baeldung.com/java-immutable-list)
 
 Note: also contains part of the code for the article
 [How to Filter a Collection in Java](https://www.baeldung.com/java-collection-filtering).

core-java-modules/core-java-9/pom.xml

@@ -37,6 +37,11 @@
             <version>${junit.platform.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -69,6 +74,7 @@
         <maven.compiler.source>1.9</maven.compiler.source>
         <maven.compiler.target>1.9</maven.compiler.target>
         <guava.version>25.1-jre</guava.version>
+        <commons-collections4.version>4.1</commons-collections4.version>
     </properties>
 
 </project>

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/list/immutable/ImmutableArrayListUnitTest.java

@@ -1,56 +1,48 @@
-package org.baeldung.java.collections;
+package com.baeldung.java9.list.immutable;
 
 import com.google.common.collect.ImmutableList;
 import org.apache.commons.collections4.ListUtils;
 import org.junit.Test;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
-public class CoreJavaCollectionsUnitTest {
-
-    private static final Logger LOG = LoggerFactory.getLogger(CoreJavaCollectionsUnitTest.class);
-
-
-    // tests -
-
-    @Test
-    public final void givenUsingTheJdk_whenArrayListIsSynchronized_thenCorrect() {
-        final List<String> list = new ArrayList<String>(Arrays.asList("one", "two", "three"));
-        final List<String> synchronizedList = Collections.synchronizedList(list);
-        LOG.debug("Synchronized List is: " + synchronizedList);
-    }
+public class ImmutableArrayListUnitTest {
 
     @Test(expected = UnsupportedOperationException.class)
-    public final void givenUsingTheJdk_whenUnmodifiableListIsCreatedFromOriginal_thenNoLongerModifiable() {
-        final List<String> list = new ArrayList<String>(Arrays.asList("one", "two", "three"));
+    public final void givenUsingTheJdk_whenUnmodifiableListIsCreated_thenNotModifiable() {
+        final List<String> list = new ArrayList<>(Arrays.asList("one", "two", "three"));
         final List<String> unmodifiableList = Collections.unmodifiableList(list);
         unmodifiableList.add("four");
     }
 
     @Test(expected = UnsupportedOperationException.class)
-    public final void givenUsingGuava_whenUnmodifiableListIsCreatedFromOriginal_thenNoLongerModifiable() {
-        final List<String> list = new ArrayList<String>(Arrays.asList("one", "two", "three"));
+    public final void givenUsingTheJava9_whenUnmodifiableListIsCreated_thenNotModifiable() {
+        final List<String> list = new ArrayList<>(Arrays.asList("one", "two", "three"));
+        final List<String> unmodifiableList = List.of(list.toArray(new String[]{}));
+        unmodifiableList.add("four");
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public final void givenUsingGuava_whenUnmodifiableListIsCreated_thenNotModifiable() {
+        final List<String> list = new ArrayList<>(Arrays.asList("one", "two", "three"));
         final List<String> unmodifiableList = ImmutableList.copyOf(list);
         unmodifiableList.add("four");
     }
 
     @Test(expected = UnsupportedOperationException.class)
-    public final void givenUsingGuavaBuilder_whenUnmodifiableListIsCreatedFromOriginal_thenNoLongerModifiable() {
-        final List<String> list = new ArrayList<String>(Arrays.asList("one", "two", "three"));
+    public final void givenUsingGuavaBuilder_whenUnmodifiableListIsCreated_thenNoLongerModifiable() {
+        final List<String> list = new ArrayList<>(Arrays.asList("one", "two", "three"));
         final ImmutableList<String> unmodifiableList = ImmutableList.<String>builder().addAll(list).build();
         unmodifiableList.add("four");
     }
 
     @Test(expected = UnsupportedOperationException.class)
-    public final void givenUsingCommonsCollections_whenUnmodifiableListIsCreatedFromOriginal_thenNoLongerModifiable() {
-        final List<String> list = new ArrayList<String>(Arrays.asList("one", "two", "three"));
+    public final void givenUsingCommonsCollections_whenUnmodifiableListIsCreated_thenNotModifiable() {
+        final List<String> list = new ArrayList<>(Arrays.asList("one", "two", "three"));
         final List<String> unmodifiableList = ListUtils.unmodifiableList(list);
         unmodifiableList.add("four");
     }
-
 }

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

@@ -75,7 +75,7 @@
                         <manifest>
                             <addClasspath>true</addClasspath>
                             <classpathPrefix>libs/</classpathPrefix>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </manifest>
                     </archive>
                 </configuration>
@@ -94,7 +94,7 @@
                             <archiveBaseDirectory>${project.basedir}</archiveBaseDirectory>
                             <archive>
                                 <manifest>
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                    <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                                 </manifest>
                             </archive>
                             <descriptorRefs>
@@ -118,7 +118,7 @@
                             <shadedArtifactAttached>true</shadedArtifactAttached>
                             <transformers>
                                 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                    <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                                 </transformer>
                             </transformers>
                         </configuration>
@@ -133,7 +133,7 @@
                 <executions>
                     <execution>
                         <configuration>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                             <attachToBuild>true</attachToBuild>
                             <filename>${project.build.finalName}-onejar.${project.packaging}</filename>
                         </configuration>
@@ -155,7 +155,7 @@
                         </goals>
                         <configuration>
                             <classifier>spring-boot</classifier>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </configuration>
                     </execution>
                 </executions>

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

@@ -3,9 +3,8 @@
 This module contains articles about the Java ArrayList collection
 
 ### Relevant Articles: 
-- [Immutable ArrayList in Java](http://www.baeldung.com/java-immutable-list)
-- [Guide to the Java ArrayList](http://www.baeldung.com/java-arraylist)
-- [Add Multiple Items to an Java ArrayList](http://www.baeldung.com/java-add-items-array-list)
+- [Guide to the Java ArrayList](https://www.baeldung.com/java-arraylist)
+- [Add Multiple Items to an Java ArrayList](https://www.baeldung.com/java-add-items-array-list)
 - [ClassCastException: Arrays$ArrayList cannot be cast to ArrayList](https://www.baeldung.com/java-classcastexception-arrays-arraylist)
 - [Multi Dimensional ArrayList in Java](https://www.baeldung.com/java-multi-dimensional-arraylist)
 - [Removing an Element From an ArrayList](https://www.baeldung.com/java-arraylist-remove-element)

core-java-modules/core-java-collections-array-list/src/test/java/com/baeldung/collections/ArrayListUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.collections;
+package com.baeldung.collections;
 
 import com.google.common.collect.Sets;
 import org.junit.Before;

core-java-modules/core-java-collections-array-list/src/test/java/com/baeldung/collections/CoreJavaCollectionsUnitTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.collections;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.commons.collections4.ListUtils;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+public class CoreJavaCollectionsUnitTest {
+
+    private static final Logger LOG = LoggerFactory.getLogger(CoreJavaCollectionsUnitTest.class);
+
+    @Test
+    public final void givenUsingTheJdk_whenArrayListIsSynchronized_thenCorrect() {
+        final List<String> list = new ArrayList<>(Arrays.asList("one", "two", "three"));
+        final List<String> synchronizedList = Collections.synchronizedList(list);
+        LOG.debug("Synchronized List is: " + synchronizedList);
+    }
+
+}

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

@@ -3,13 +3,13 @@
 This module contains articles about the Java List collection
 
 ### Relevant Articles: 
-- [Check If Two Lists are Equal in Java](http://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
+- [Check If Two Lists are Equal in Java](https://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)
 - [Java 8 Streams: Find Items From One List Based On Values From Another List](https://www.baeldung.com/java-streams-find-list-items)
-- [A Guide to the Java LinkedList](http://www.baeldung.com/java-linkedlist)
-- [Java List UnsupportedOperationException](http://www.baeldung.com/java-list-unsupported-operation-exception)
+- [A Guide to the Java LinkedList](https://www.baeldung.com/java-linkedlist)
+- [Java List UnsupportedOperationException](https://www.baeldung.com/java-list-unsupported-operation-exception)
 - [Java List Initialization in One Line](https://www.baeldung.com/java-init-list-one-line)
 - [Ways to Iterate Over a List in Java](https://www.baeldung.com/java-iterate-list)
-- [Flattening Nested Collections in Java](http://www.baeldung.com/java-flatten-nested-collections)
+- [Flattening Nested Collections in Java](https://www.baeldung.com/java-flatten-nested-collections)
 - [Intersection of Two Lists in Java](https://www.baeldung.com/java-lists-intersection)
 - [Searching for a String in an ArrayList](https://www.baeldung.com/java-search-string-arraylist)
 - [[<-- Prev]](/core-java-modules/core-java-collections-list)[[Next -->]](/core-java-modules/core-java-collections-list-3)

core-java-modules/core-java-collections-list-2/src/test/java/com/baeldung/java/list/ListAssertJUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.lists;
+package com.baeldung.java.list;
 
 import org.junit.Test;
 

core-java-modules/core-java-collections-list-2/src/test/java/com/baeldung/java/list/ListJUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.lists;
+package com.baeldung.java.list;
 
 import org.junit.Assert;
 import org.junit.Test;

core-java-modules/core-java-collections-list-2/src/test/java/com/baeldung/java/list/ListTestNgUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.lists;
+package com.baeldung.java.list;
 
 import org.junit.Test;
 

core-java-modules/core-java-collections-list-2/src/test/java/org/baeldung/java/lists/README.md

@@ -1,2 +0,0 @@
-### Relevant Articles:
-- [Check If Two Lists are Equal in Java](http://www.baeldung.com/java-test-a-list-for-ordinality-and-equality)

core-java-modules/core-java-collections-list/src/test/java/com/baeldung/collections/JavaCollectionCleanupUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.collections;
+package com.baeldung.collections;
 
 import static org.hamcrest.Matchers.hasSize;
 import static org.junit.Assert.assertThat;

core-java-modules/core-java-collections-list/src/test/java/com/baeldung/list/random/RandomListElementUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung;
+package com.baeldung.list.random;
 
 import com.google.common.collect.Lists;
 import org.junit.Test;

core-java-modules/core-java-concurrency-advanced-2/src/main/java/com/baeldung/threadlocalrandom/ThreadLocalRandomBenchMarkRunner.java

@@ -1,22 +1,27 @@
 package com.baeldung.threadlocalrandom;
 
 import org.openjdk.jmh.runner.Runner;
-import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.ChainedOptionsBuilder;
 import org.openjdk.jmh.runner.options.OptionsBuilder;
 
+import com.google.common.collect.ImmutableList;
+
 public class ThreadLocalRandomBenchMarkRunner {
 
     public static void main(String[] args) throws Exception {
 
-        Options options = new OptionsBuilder().include(ThreadLocalRandomBenchMarker.class.getSimpleName())
-            .threads(1)
+        ChainedOptionsBuilder options = new OptionsBuilder().include(ThreadLocalRandomBenchMarker.class.getSimpleName())
             .forks(1)
             .shouldFailOnError(true)
             .shouldDoGC(true)
-            .jvmArgs("-server")
-            .build();
-
-        new Runner(options).run();
+            .jvmArgs("-server");
 
+        for (Integer i : ImmutableList.of(1, 2, 8, 32)) {
+            new Runner(
+                    options
+                            .threads(i)
+                            .build())
+                    .run();
+        }
     }
 }

core-java-modules/core-java-concurrency-advanced-2/src/main/java/com/baeldung/threadlocalrandom/ThreadLocalRandomBenchMarker.java

@@ -1,64 +1,34 @@
 package com.baeldung.threadlocalrandom;
 
-import java.util.ArrayList;
-import java.util.List;
 import java.util.Random;
-import java.util.concurrent.Callable;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
-import org.openjdk.jmh.annotations.Level;
 import org.openjdk.jmh.annotations.Mode;
 import org.openjdk.jmh.annotations.OutputTimeUnit;
 import org.openjdk.jmh.annotations.Scope;
-import org.openjdk.jmh.annotations.Setup;
 import org.openjdk.jmh.annotations.State;
 import org.openjdk.jmh.annotations.Warmup;
 
-@BenchmarkMode(Mode.AverageTime)
+@BenchmarkMode(Mode.Throughput)
 @Warmup(iterations = 1)
 @OutputTimeUnit(TimeUnit.MICROSECONDS)
 @State(Scope.Benchmark)
 public class ThreadLocalRandomBenchMarker {
+    private final Random random = new Random();
 
-    List<Callable<Integer>> randomCallables = new ArrayList<>();
-    List<Callable<Integer>> threadLocalRandomCallables = new ArrayList<>();
-
-    @Setup(Level.Iteration)
-    public void init() {
-        Random random = new Random();
-        randomCallables = new ArrayList<>();
-        threadLocalRandomCallables = new ArrayList<>();
-        for (int i = 0; i < 1000; i++) {
-            randomCallables.add(() -> {
-                return random.nextInt();
-            });
-        }
-
-        for (int i = 0; i < 1000; i++) {
-            threadLocalRandomCallables.add(() -> {
-                return ThreadLocalRandom.current()
-                    .nextInt();
-            });
-        }
+    @Benchmark
+    public int randomValuesUsingRandom() {
+        return random.nextInt();
     }
 
     @Benchmark
-    public void randomValuesUsingRandom() throws InterruptedException {
-        ExecutorService executor = Executors.newWorkStealingPool();
-        executor.invokeAll(randomCallables);
-        executor.shutdown();
-    }
-
-    @Benchmark
-    public void randomValuesUsingThreadLocalRandom() throws InterruptedException {
-        ExecutorService executor = Executors.newWorkStealingPool();
-        executor.invokeAll(threadLocalRandomCallables);
-        executor.shutdown();
+    public int randomValuesUsingThreadLocalRandom() {
+        return ThreadLocalRandom
+                .current()
+                .nextInt();
     }
 
 }

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/workstealing/PrimeNumbers.java

@@ -0,0 +1,85 @@
+package com.baeldung.workstealing;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.ForkJoinTask;
+import java.util.concurrent.RecursiveAction;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class PrimeNumbers extends RecursiveAction {
+
+    private int lowerBound;
+    private int upperBound;
+    private int granularity;
+    static final List<Integer> GRANULARITIES
+      = Arrays.asList(1, 10, 100, 1000, 10000);
+    private AtomicInteger noOfPrimeNumbers;
+
+    PrimeNumbers(int lowerBound, int upperBound, int granularity, AtomicInteger noOfPrimeNumbers) {
+        this.lowerBound = lowerBound;
+        this.upperBound = upperBound;
+        this.granularity = granularity;
+        this.noOfPrimeNumbers = noOfPrimeNumbers;
+    }
+
+    PrimeNumbers(int upperBound) {
+        this(1, upperBound, 100, new AtomicInteger(0));
+    }
+
+    private PrimeNumbers(int lowerBound, int upperBound, AtomicInteger noOfPrimeNumbers) {
+        this(lowerBound, upperBound, 100, noOfPrimeNumbers);
+    }
+
+    private List<PrimeNumbers> subTasks() {
+        List<PrimeNumbers> subTasks = new ArrayList<>();
+
+        for (int i = 1; i <= this.upperBound / granularity; i++) {
+            int upper = i * granularity;
+            int lower = (upper - granularity) + 1;
+            subTasks.add(new PrimeNumbers(lower, upper, noOfPrimeNumbers));
+        }
+        return subTasks;
+    }
+
+    @Override
+    protected void compute() {
+        if (((upperBound + 1) - lowerBound) > granularity) {
+            ForkJoinTask.invokeAll(subTasks());
+        } else {
+            findPrimeNumbers();
+        }
+    }
+
+    void findPrimeNumbers() {
+        for (int num = lowerBound; num <= upperBound; num++) {
+            if (isPrime(num)) {
+                noOfPrimeNumbers.getAndIncrement();
+            }
+        }
+    }
+
+    private boolean isPrime(int number) {
+        if (number == 2) {
+            return true;
+        }
+
+        if (number == 1 || number % 2 == 0) {
+            return false;
+        }
+
+        int noOfNaturalNumbers = 0;
+
+        for (int i = 1; i <= number; i++) {
+            if (number % i == 0) {
+                noOfNaturalNumbers++;
+            }
+        }
+
+        return noOfNaturalNumbers == 2;
+    }
+
+    public int noOfPrimeNumbers() {
+        return noOfPrimeNumbers.intValue();
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/rejection/SaturationPolicyUnitTest.java

@@ -33,7 +33,7 @@ public class SaturationPolicyUnitTest {
     @Test
     public void givenAbortPolicy_WhenSaturated_ThenShouldThrowRejectedExecutionException() {
         executor = new ThreadPoolExecutor(1, 1, 0, MILLISECONDS, new SynchronousQueue<>(), new AbortPolicy());
-        executor.execute(() -> waitFor(100));
+        executor.execute(() -> waitFor(250));
 
         assertThatThrownBy(() -> executor.execute(() -> System.out.println("Will be rejected"))).isInstanceOf(RejectedExecutionException.class);
     }
@@ -42,13 +42,13 @@ public class SaturationPolicyUnitTest {
     @Test
     public void givenCallerRunsPolicy_WhenSaturated_ThenTheCallerThreadRunsTheTask() {
         executor = new ThreadPoolExecutor(1, 1, 0, MILLISECONDS, new SynchronousQueue<>(), new CallerRunsPolicy());
-        executor.execute(() -> waitFor(100));
+        executor.execute(() -> waitFor(250));
 
-        long startTime = System.nanoTime();
-        executor.execute(() -> waitFor(100));
-        double blockedDuration = (System.nanoTime() - startTime) / 1_000_000.0;
+        long startTime = System.currentTimeMillis();
+        executor.execute(() -> waitFor(500));
+        long blockedDuration = System.currentTimeMillis() - startTime;
 
-        assertThat(blockedDuration).isGreaterThanOrEqualTo(100);
+        assertThat(blockedDuration).isGreaterThanOrEqualTo(500);
     }
 
     @Test

core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/workstealing/PrimeNumbersUnitTest.java

@@ -0,0 +1,101 @@
+package com.baeldung.workstealing;
+
+import org.junit.Test;
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.logging.Logger;
+
+import static org.junit.Assert.fail;
+
+public class PrimeNumbersUnitTest {
+
+    private static Logger logger = Logger.getAnonymousLogger();
+
+    @Test
+    public void givenPrimesCalculated_whenUsingPoolsAndOneThread_thenOneThreadSlowest() {
+        Options opt = new OptionsBuilder()
+          .include(Benchmarker.class.getSimpleName())
+          .forks(1)
+          .build();
+
+        try {
+            new Runner(opt).run();
+        } catch (RunnerException e) {
+            fail();
+        }
+    }
+
+    @Test
+    public void givenNewWorkStealingPool_whenGettingPrimes_thenStealCountChanges() {
+        StringBuilder info = new StringBuilder();
+
+        for (int granularity : PrimeNumbers.GRANULARITIES) {
+            int parallelism = ForkJoinPool.getCommonPoolParallelism();
+            ForkJoinPool pool =
+              (ForkJoinPool) Executors.newWorkStealingPool(parallelism);
+
+            stealCountInfo(info, granularity, pool);
+        }
+        logger.info("\nExecutors.newWorkStealingPool ->" + info.toString());
+    }
+
+    @Test
+    public void givenCommonPool_whenGettingPrimes_thenStealCountChangesSlowly() {
+        StringBuilder info = new StringBuilder();
+
+        for (int granularity : PrimeNumbers.GRANULARITIES) {
+            ForkJoinPool pool = ForkJoinPool.commonPool();
+            stealCountInfo(info, granularity, pool);
+        }
+        logger.info("\nForkJoinPool.commonPool ->" + info.toString());
+    }
+
+    private void stealCountInfo(StringBuilder info, int granularity, ForkJoinPool forkJoinPool) {
+        PrimeNumbers primes = new PrimeNumbers(1, 10000, granularity, new AtomicInteger(0));
+        forkJoinPool.invoke(primes);
+        forkJoinPool.shutdown();
+
+        long steals = forkJoinPool.getStealCount();
+        String output = "\nGranularity: [" + granularity + "], Steals: [" + steals + "]";
+        info.append(output);
+    }
+
+
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.MILLISECONDS)
+    @State(Scope.Benchmark)
+    @Fork(value = 2, warmups = 1, jvmArgs = {"-Xms2G", "-Xmx2G"})
+    public static class Benchmarker {
+
+        @Benchmark
+        public void singleThread() {
+            PrimeNumbers primes = new PrimeNumbers(10000);
+            primes.findPrimeNumbers(); // get prime numbers using a single thread
+        }
+
+        @Benchmark
+        public void commonPoolBenchmark() {
+            PrimeNumbers primes = new PrimeNumbers(10000);
+            ForkJoinPool pool = ForkJoinPool.commonPool();
+            pool.invoke(primes);
+            pool.shutdown();
+        }
+
+        @Benchmark
+        public void newWorkStealingPoolBenchmark() {
+            PrimeNumbers primes = new PrimeNumbers(10000);
+            int parallelism = ForkJoinPool.getCommonPoolParallelism();
+            ForkJoinPool stealer = (ForkJoinPool) Executors.newWorkStealingPool(parallelism);
+            stealer.invoke(primes);
+            stealer.shutdown();
+        }
+    }
+}

core-java-modules/core-java-concurrency-collections/src/test/java/com/baeldung/java/stream/ThreadPoolInParallelStreamIntegrationTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.streams;
+package com.baeldung.java.stream;
 
 import org.junit.Test;
 

core-java-modules/core-java-date-operations-2/src/test/java/com/baeldung/offsetdatetime/ConvertToOffsetDateTimeUnitTest.java

@@ -4,6 +4,7 @@ import org.junit.Test;
 
 import java.time.OffsetDateTime;
 import java.util.Date;
+import java.util.TimeZone;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
@@ -18,12 +19,19 @@ public class ConvertToOffsetDateTimeUnitTest {
 
     @Test
     public void givenDate_whenHasOffset_thenConvertWithOffset() {
+        TimeZone prevTimezone = TimeZone.getDefault();
+        TimeZone.setDefault(TimeZone.getTimeZone("UTC"));
+
         Date date = new Date();
         date.setHours(6);
         date.setMinutes(30);
+
         OffsetDateTime odt = ConvertToOffsetDateTime.convert(date, 3, 30);
         assertEquals(10, odt.getHour());
         assertEquals(0, odt.getMinute());
+
+        // Reset the timezone to its original value to prevent side effects
+        TimeZone.setDefault(prevTimezone);
     }
 
 }

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

@@ -2,4 +2,7 @@
 
 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)

core-java-modules/core-java-exceptions-2/pom.xml

@@ -13,12 +13,24 @@
 		<version>0.0.1-SNAPSHOT</version>
 		<relativePath>../../parent-java</relativePath>
 	</parent>
+	
+	<dependencies>
+		<!-- test scoped -->
+		<dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj-core.version}</version>
+            <scope>test</scope>
+        </dependency>
+	</dependencies>
 
 	<description> </description>
 	<url>http://maven.apache.org</url>
 
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<!-- testing -->
+		<assertj-core.version>3.10.0</assertj-core.version>
 	</properties>
 
 </project>

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

@@ -0,0 +1,28 @@
+package com.baeldung.exceptions;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.net.UnknownHostException;
+
+public class UnknownHostExceptionHandling {
+
+    public static int getResponseCode(String hostname) throws IOException {
+        URL url = new URL(hostname.trim());
+        HttpURLConnection con = (HttpURLConnection) url.openConnection();
+        int resCode = -1;
+        try {
+            resCode = con.getResponseCode();
+        } catch (UnknownHostException e){
+            con.disconnect();
+        }
+        return resCode;
+    }
+    
+    public static int getResponseCodeUnhandled(String hostname) throws IOException {
+        URL url = new URL(hostname.trim());
+        HttpURLConnection con = (HttpURLConnection) url.openConnection();
+        int resCode = con.getResponseCode();
+        return resCode;
+    }
+}

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

@@ -0,0 +1,15 @@
+package com.baeldung.exceptions;
+
+import java.io.IOException;
+import java.net.UnknownHostException;
+
+import org.junit.Test;
+
+public class UnknownHostExceptionHandlingUnitTest {
+
+    @Test(expected = UnknownHostException.class)
+    public void givenUnknownHost_whenResolve_thenUnknownHostException() throws IOException {
+        UnknownHostExceptionHandling.getResponseCodeUnhandled("http://locaihost");
+    }
+    
+}

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

@@ -13,4 +13,5 @@ This module contains articles about core Java input and output (IO)
 - [Getting a File’s Mime Type in Java](https://www.baeldung.com/java-file-mime-type)
 - [How to Write to a CSV File in Java](https://www.baeldung.com/java-csv)
 - [How to Avoid the Java FileNotFoundException When Loading Resources](https://www.baeldung.com/java-classpath-resource-cannot-be-opened)
+- [Create a Directory in Java](https://www.baeldung.com/java-create-directory)
 - [[More -->]](/core-java-modules/core-java-io-2)

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

@@ -99,7 +99,7 @@
                         <manifest>
                             <addClasspath>true</addClasspath>
                             <classpathPrefix>libs/</classpathPrefix>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </manifest>
                     </archive>
                 </configuration>
@@ -118,7 +118,7 @@
                             <archiveBaseDirectory>${project.basedir}</archiveBaseDirectory>
                             <archive>
                                 <manifest>
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                    <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                                 </manifest>
                             </archive>
                             <descriptorRefs>
@@ -142,7 +142,7 @@
                             <shadedArtifactAttached>true</shadedArtifactAttached>
                             <transformers>
                                 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                    <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                                 </transformer>
                             </transformers>
                         </configuration>
@@ -157,7 +157,7 @@
                 <executions>
                     <execution>
                         <configuration>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                             <attachToBuild>true</attachToBuild>
                             <filename>${project.build.finalName}-onejar.${project.packaging}</filename>
                         </configuration>
@@ -179,7 +179,7 @@
                         </goals>
                         <configuration>
                             <classifier>spring-boot</classifier>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </configuration>
                     </execution>
                 </executions>

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

@@ -24,9 +24,14 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
-            <version>5.5.1</version>
+            <version>${jupiter.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>${jupiter.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-core</artifactId>

core-java-modules/core-java-jndi/src/test/java/com/baeldung/jndi/exceptions/JndiExceptionsUnitTest.java

@@ -17,7 +17,6 @@ import org.springframework.mock.jndi.SimpleNamingContextBuilder;
 @TestMethodOrder(MethodOrderer.OrderAnnotation.class)
 public class JndiExceptionsUnitTest {
 
-    @Disabled
     @Test
     @Order(1)
     void givenNoContext_whenLookupObject_thenThrowNoInitialContext() {

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

@@ -10,3 +10,5 @@ This module contains articles about working with the Java Virtual Machine (JVM).
 - [Class Loaders in Java](https://www.baeldung.com/java-classloaders)
 - [A Guide to System.exit()](https://www.baeldung.com/java-system-exit)
 - [Guide to System.gc()](https://www.baeldung.com/java-system-gc)
+- [Runtime.getRuntime().halt() vs System.exit() in Java](https://www.baeldung.com/java-runtime-halt-vs-system-exit)
+- [Adding Shutdown Hooks for JVM Applications](https://www.baeldung.com/jvm-shutdown-hooks)

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

@@ -6,4 +6,5 @@ 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)
 - [[<-- Prev]](/core-java-modules/core-java-lang)

core-java-modules/core-java-lang-2/pom.xml

@@ -15,6 +15,11 @@
     </parent>
 
     <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>3.9</version>
+        </dependency>
         <dependency>
             <groupId>commons-beanutils</groupId>
             <artifactId>commons-beanutils</artifactId>

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsPair.java

@@ -0,0 +1,20 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import org.apache.commons.lang3.tuple.ImmutablePair;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.Comparator;
+import java.util.List;
+
+class MultipleReturnValuesUsingApacheCommonsPair {
+
+    static ImmutablePair<Coordinates, Double> getMostDistantPoint(
+      List<Coordinates> coordinatesList,
+      Coordinates target) {
+        return coordinatesList.stream()
+          .map(coordinates -> ImmutablePair.of(coordinates, coordinates.calculateDistance(target)))
+          .max(Comparator.comparingDouble(Pair::getRight))
+          .get();
+
+    }
+}

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsTriple.java

@@ -0,0 +1,23 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import org.apache.commons.lang3.tuple.ImmutableTriple;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+class MultipleReturnValuesUsingApacheCommonsTriple {
+
+    static ImmutableTriple<Double, Double, Double> getMinAvgMaxTriple(
+      List<Coordinates> coordinatesList,
+      Coordinates target) {
+
+        List<Double> distanceList = coordinatesList.stream()
+          .map(coordinates -> coordinates.calculateDistance(target))
+          .collect(Collectors.toList());
+        Double minDistance = distanceList.stream().mapToDouble(Double::doubleValue).min().getAsDouble();
+        Double avgDistance = distanceList.stream().mapToDouble(Double::doubleValue).average().orElse(0.0D);
+        Double maxDistance = distanceList.stream().mapToDouble(Double::doubleValue).max().getAsDouble();
+
+        return ImmutableTriple.of(minDistance, avgDistance, maxDistance);
+    }
+}

core-java-modules/core-java-lang-2/src/test/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsPairUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import org.apache.commons.lang3.tuple.ImmutablePair;
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class MultipleReturnValuesUsingApacheCommonsPairUnitTest {
+
+    @Test
+    void whenUsingPair_thenMultipleFieldsAreReturned() {
+
+        List<Coordinates> coordinatesList = new ArrayList<>();
+        coordinatesList.add(new Coordinates(1, 1, "home"));
+        coordinatesList.add(new Coordinates(2, 2, "school"));
+        coordinatesList.add(new Coordinates(3, 3, "hotel"));
+
+        Coordinates target = new Coordinates(5, 5, "gym");
+
+        ImmutablePair<Coordinates, Double> mostDistantPoint = MultipleReturnValuesUsingApacheCommonsPair.getMostDistantPoint(coordinatesList, target);
+
+        assertEquals(1, mostDistantPoint.getLeft().getLongitude());
+        assertEquals(1, mostDistantPoint.getLeft().getLatitude());
+        assertEquals("home", mostDistantPoint.getLeft().getPlaceName());
+        assertEquals(5.66, BigDecimal.valueOf(mostDistantPoint.getRight()).setScale(2, RoundingMode.HALF_UP).doubleValue());
+
+    }
+
+}

core-java-modules/core-java-lang-2/src/test/java/com/baeldung/methodmultiplereturnvalues/MultipleReturnValuesUsingApacheCommonsTripleUnitTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.methodmultiplereturnvalues;
+
+import org.apache.commons.lang3.tuple.ImmutableTriple;
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class MultipleReturnValuesUsingApacheCommonsTripleUnitTest {
+
+    @Test
+    void whenUsingTriple_thenMultipleFieldsAreReturned() {
+
+        List<Coordinates> coordinatesList = new ArrayList<>();
+        coordinatesList.add(new Coordinates(1, 1, "home"));
+        coordinatesList.add(new Coordinates(2, 2, "school"));
+        coordinatesList.add(new Coordinates(3, 3, "hotel"));
+
+        Coordinates target = new Coordinates(5, 5, "gym");
+
+        ImmutableTriple<Double, Double, Double> minAvgMax = MultipleReturnValuesUsingApacheCommonsTriple.getMinAvgMaxTriple(coordinatesList, target);
+
+        assertEquals(2.83, scaleDouble(minAvgMax.left));   //min
+        assertEquals(4.24, scaleDouble(minAvgMax.middle)); //avg
+        assertEquals(5.66, scaleDouble(minAvgMax.right));  //max
+    }
+
+    private double scaleDouble(Double d) {
+        return BigDecimal.valueOf(d).setScale(2, RoundingMode.HALF_UP).doubleValue();
+    }
+}

core-java-modules/core-java-lang-oop-3/README.md

@@ -8,9 +8,9 @@ This module contains articles about Object-oriented programming (OOP) in Java
 - [Guide to the super Java Keyword](https://www.baeldung.com/java-super)
 - [Guide to the this Java Keyword](https://www.baeldung.com/java-this)
 - [Java ‘public’ Access Modifier](https://www.baeldung.com/java-public-keyword)
-- [Composition, Aggregation and Association in Java](https://www.baeldung.com/java-composition-aggregation-association)
+- [Composition, Aggregation, and Association in Java](https://www.baeldung.com/java-composition-aggregation-association)
 - [Nested Classes in Java](https://www.baeldung.com/java-nested-classes)
 - [A Guide to Inner Interfaces in Java](https://www.baeldung.com/java-inner-interfaces)
 - [Java Classes and Objects](https://www.baeldung.com/java-classes-objects)
 - [Java Interfaces](https://www.baeldung.com/java-interfaces)
-- [[<-- Prev]](/core-java-modules/core-java-lang-oop-2)[[More -->]](/core-java-modules/core-java-lang-oop-4)
+- [[<-- Prev]](/core-java-modules/core-java-lang-oop-2)[[More -->]](/core-java-modules/core-java-lang-oop-4)

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-perf/README.md

@@ -9,3 +9,4 @@ This module contains articles about performance of Java applications
 - [OutOfMemoryError: GC Overhead Limit Exceeded](http://www.baeldung.com/java-gc-overhead-limit-exceeded)
 - [Basic Introduction to JMX](http://www.baeldung.com/java-management-extensions)
 - [Monitoring Java Applications with Flight Recorder](https://www.baeldung.com/java-flight-recorder-monitoring)
+- [Branch Prediction in Java](https://www.baeldung.com/java-branch-prediction)

core-java-modules/core-java-string-algorithms-3/README.md

@@ -3,3 +3,5 @@
 This module contains articles about string-related algorithms.
 
 ### Relevant Articles:
+
+- [Check if Two Strings are Anagrams in Java](https://www.baeldung.com/java-strings-anagrams)

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

@@ -8,4 +8,5 @@ This module contains articles about string operations.
 - [String Initialization in Java](https://www.baeldung.com/java-string-initialization)
 - [String toLowerCase and toUpperCase Methods in Java](https://www.baeldung.com/java-string-convert-case)
 - [Java String equalsIgnoreCase()](https://www.baeldung.com/java-string-equalsignorecase)
+- [How to avoid String contains() Case Insensitive in Java](https://www.baeldung.com/how-to-avoid-string-contains-case-insensitive-in-java)
 - More articles: [[<-- prev]](../core-java-string-operations)

core-java-modules/core-java-string-operations-2/pom.xml

@@ -1,6 +1,7 @@
 <?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>
     <artifactId>core-java-string-operations-2</artifactId>
     <version>0.1.0-SNAPSHOT</version>
@@ -51,6 +52,18 @@
             <version>${org.hamcrest.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh-generator.version}</version>
+        </dependency>
+
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
@@ -61,6 +74,29 @@
 
     <build>
         <finalName>core-java-string-operations-2</finalName>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <version>3.2.0</version>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                        <configuration>
+                            <transformers>
+                                <transformer
+                                    implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+                                    <mainClass>org.openjdk.jmh.Main</mainClass>
+                                </transformer>
+                            </transformers>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
         <resources>
             <resource>
                 <directory>src/main/resources</directory>

core-java-modules/core-java-string-operations-2/src/main/java/com/baeldung/contains/CaseInsensitiveWorkarounds.java

@@ -0,0 +1,78 @@
+package com.baeldung.contains;
+
+import java.util.concurrent.TimeUnit;
+import java.util.regex.Pattern;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+
+/**
+ * Based on https://github.com/tedyoung/indexof-contains-benchmark
+ */
+@Fork(5)
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+public class CaseInsensitiveWorkarounds {
+
+    private String src;
+    private String dest;
+    private Pattern pattern;
+
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+
+    @Setup
+    public void setup() {
+        src = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum";
+        dest = "eiusmod";
+        pattern = Pattern.compile(Pattern.quote(dest), Pattern.CASE_INSENSITIVE);
+    }
+
+    // toLowerCase() and contains()
+    @Benchmark
+    public boolean lowerCaseContains() {
+        return src.toLowerCase()
+            .contains(dest.toLowerCase());
+    }
+
+    // matches() with Regular Expressions
+    @Benchmark
+    public boolean matchesRegularExpression() {
+        return src.matches("(?i).*" + dest + ".*");
+    }
+
+    public boolean processRegionMatches(String localSrc, String localDest) {
+        for (int i = localSrc.length() - localDest.length(); i >= 0; i--)
+            if (localSrc.regionMatches(true, i, localDest, 0, localDest.length()))
+                return true;
+        return false;        
+    }
+    
+    // String regionMatches()
+    @Benchmark
+    public boolean regionMatches() {
+        return processRegionMatches(src, dest);
+    }
+
+    // Pattern CASE_INSENSITIVE with regexp
+    @Benchmark
+    public boolean patternCaseInsensitiveRegexp() {
+        return pattern.matcher(src)
+            .find();
+    }
+
+    // Apache Commons StringUtils containsIgnoreCase
+    @Benchmark
+    public boolean apacheCommonsStringUtils() {
+        return org.apache.commons.lang3.StringUtils.containsIgnoreCase(src, dest);
+    }
+
+}

core-java-modules/core-java-string-operations-2/src/test/java/com/baeldung/contains/CaseInsensitiveWorkaroundsUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.contains;
+
+import org.apache.commons.lang3.StringUtils;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.regex.Pattern;
+
+/**
+ * BAEL-3739: Different ways to solve the contains() case insensitive behavior.
+ */
+public class CaseInsensitiveWorkaroundsUnitTest {
+
+    private String src = "Lorem ipsum dolor sit amet";
+    private String dest = "lorem";
+
+    @Test
+    public void givenString_whenCallingContainsWithToLowerOrUpperCase_shouldReturnTrue() {
+        // Use toLowerCase to avoid case insensitive issues
+        Assert.assertTrue(src.toLowerCase().contains(dest.toLowerCase()));
+
+        // Use toUpperCase to avoid case insensitive issues
+        Assert.assertTrue(src.toUpperCase().contains(dest.toUpperCase()));
+    }
+    
+    @Test
+    public void givenString_whenCallingStringMatches_thenReturnsTrue() {
+        // Use String Matches to avoid case insensitive issues
+        Assert.assertTrue(src.matches("(?i).*" + dest + ".*"));
+    }
+    
+    @Test
+    public void givenString_whenCallingStringRegionMatches_thenReturnsTrue() {
+        // Use String Region Matches to avoid case insensitive issues
+        CaseInsensitiveWorkarounds comparator = new CaseInsensitiveWorkarounds();
+        Assert.assertTrue(comparator.processRegionMatches(src, dest));
+    }
+    
+    
+    @Test
+    public void givenString_whenCallingPaternCompileMatcherFind_thenReturnsTrue() {
+        // Use Pattern Compile Matcher and Find to avoid case insensitive issues
+        Assert.assertTrue(Pattern.compile(Pattern.quote(dest), 
+            Pattern.CASE_INSENSITIVE) .matcher(src) .find());
+    }
+    
+    @Test
+    public void givenString_whenCallingStringUtilsContainsIgnoreCase_thenReturnsTrue() {
+        // Use StringUtils containsIgnoreCase to avoid case insensitive issues
+        Assert.assertTrue(StringUtils.containsIgnoreCase(src, dest));
+    }
+
+}

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

@@ -49,7 +49,7 @@
                         <manifest>
                             <addClasspath>true</addClasspath>
                             <classpathPrefix>libs/</classpathPrefix>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </manifest>
                     </archive>
                 </configuration>

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

@@ -3,4 +3,5 @@
 ## Core Java 8 Cookbooks and Examples
 
 ### Relevant Articles: 
-- [An Overview of Regular Expressions Performance in Java](https://www.baeldung.com/java-regex-performance)
+- [An Overview of Regular Expressions Performance in Java](https://www.baeldung.com/java-regex-performance)
+- [Pre-compile Regex Patterns Into Pattern Objects](https://www.baeldung.com/java-regex-pre-compile)

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

@@ -99,7 +99,7 @@
                         <manifest>
                             <addClasspath>true</addClasspath>
                             <classpathPrefix>libs/</classpathPrefix>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </manifest>
                     </archive>
                 </configuration>
@@ -118,7 +118,7 @@
                             <archiveBaseDirectory>${project.basedir}</archiveBaseDirectory>
                             <archive>
                                 <manifest>
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                    <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                                 </manifest>
                             </archive>
                             <descriptorRefs>
@@ -142,7 +142,7 @@
                             <shadedArtifactAttached>true</shadedArtifactAttached>
                             <transformers>
                                 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-                                    <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                                    <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                                 </transformer>
                             </transformers>
                         </configuration>
@@ -157,7 +157,7 @@
                 <executions>
                     <execution>
                         <configuration>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                             <attachToBuild>true</attachToBuild>
                             <filename>${project.build.finalName}-onejar.${project.packaging}</filename>
                         </configuration>
@@ -179,7 +179,7 @@
                         </goals>
                         <configuration>
                             <classifier>spring-boot</classifier>
-                            <mainClass>org.baeldung.executable.ExecutableMavenJar</mainClass>
+                            <mainClass>com.baeldung.executable.ExecutableMavenJar</mainClass>
                         </configuration>
                     </execution>
                 </executions>

core-java-modules/core-java/src/main/java/org/baeldung/executable/ExecutableMavenJar.java

@@ -1,10 +0,0 @@
-package org.baeldung.executable;
-
-import javax.swing.*;
-
-public class ExecutableMavenJar {
-
-    public static void main(String[] args) {
-        JOptionPane.showMessageDialog(null, "It worked!", "Executable Jar with Maven", 1);
-    }
-}

core-java-modules/core-java/src/test/java/com/baeldung/JavaTimerLongRunningUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java;
+package com.baeldung;
 
 import org.junit.Test;
 import org.slf4j.Logger;

core-java-modules/core-java/src/test/java/com/baeldung/arrays/ArraysJoinAndSplitJUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.arrays;
+package com.baeldung.arrays;
 
 import java.util.Arrays;
 

core-java-modules/core-java/src/test/java/com/baeldung/rawtypes/RawTypesUnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.rawtypes;
+package com.baeldung.rawtypes;
 
 import java.util.ArrayList;
 import java.util.List;

core-java-modules/core-java/src/test/java/com/baeldung/sandbox/SandboxJavaManualTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.sandbox;
+package com.baeldung.sandbox;
 
 import org.junit.Test;
 import org.slf4j.Logger;

core-kotlin-2/.gitignore

@@ -1,14 +0,0 @@
-/bin/
-
-#ignore gradle
-.gradle/
-
-
-#ignore build and generated files
-build/
-node/
-out/
-
-#ignore installed node modules and package lock file
-node_modules/
-package-lock.json

core-kotlin-2/README.md

@@ -1,14 +0,0 @@
-## Core Kotlin
-
-This module contains articles about core Kotlin.
-
-### Relevant articles:
-
-- [Kotlin Scope Functions](https://www.baeldung.com/kotlin-scope-functions)
-- [Kotlin Annotations](https://www.baeldung.com/kotlin-annotations)
-- [Split a List into Parts in Kotlin](https://www.baeldung.com/kotlin-split-list-into-parts)
-- [String Comparison in Kotlin](https://www.baeldung.com/kotlin-string-comparison)
-- [Guide to JVM Platform Annotations in Kotlin](https://www.baeldung.com/kotlin-jvm-annotations)
-- [Finding an Element in a List Using Kotlin](https://www.baeldung.com/kotlin-finding-element-in-list)
-- [Kotlin Ternary Conditional Operator](https://www.baeldung.com/kotlin-ternary-conditional-operator)
-- More articles: [[<-- prev]](/core-kotlin)

core-kotlin-2/build.gradle

@@ -1,58 +0,0 @@
-
-
-group 'com.baeldung.ktor'
-version '1.0-SNAPSHOT'
-
-
-buildscript {
-    ext.kotlin_version = '1.3.30'
-
-    repositories {
-        mavenCentral()
-    }
-    dependencies {
-
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-    }
-}
-
-apply plugin: 'java'
-apply plugin: 'kotlin'
-apply plugin: 'application'
-
-mainClassName = 'APIServer.kt'
-
-sourceCompatibility = 1.8
-compileKotlin { kotlinOptions.jvmTarget = "1.8" }
-compileTestKotlin { kotlinOptions.jvmTarget = "1.8" }
-
-repositories {
-    mavenCentral()
-    jcenter()
-    maven { url "https://dl.bintray.com/kotlin/ktor" }
-}
-sourceSets {
-    main{
-        kotlin{
-            srcDirs 'com/baeldung/ktor'
-        }
-    }
-}
-
-test {
-    useJUnitPlatform()
-    testLogging {
-        events "passed", "skipped", "failed"
-    }
-}
-
-dependencies {
-    implementation "ch.qos.logback:logback-classic:1.2.1"
-    implementation "org.jetbrains.kotlin:kotlin-stdlib:${kotlin_version}"
-    testImplementation 'org.junit.jupiter:junit-jupiter:5.4.2'
-    testImplementation 'junit:junit:4.12'
-    testImplementation 'org.assertj:assertj-core:3.12.2'
-    testImplementation 'org.mockito:mockito-core:2.27.0'
-    testImplementation "org.jetbrains.kotlin:kotlin-test:${kotlin_version}"
-    testImplementation "org.jetbrains.kotlin:kotlin-test-junit5:${kotlin_version}"
-}

core-kotlin-2/gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +0,0 @@
-distributionBase=GRADLE_USER_HOME
-distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.4-bin.zip
-zipStoreBase=GRADLE_USER_HOME
-zipStorePath=wrapper/dists

core-kotlin-2/gradlew

@@ -1,188 +0,0 @@
-#!/usr/bin/env sh
-
-#
-# Copyright 2015 the original author or authors.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-##############################################################################
-##
-##  Gradle start up script for UN*X
-##
-##############################################################################
-
-# Attempt to set APP_HOME
-# Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
-done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
-
-APP_NAME="Gradle"
-APP_BASE_NAME=`basename "$0"`
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
-
-# Use the maximum available, or set MAX_FD != -1 to use that value.
-MAX_FD="maximum"
-
-warn () {
-    echo "$*"
-}
-
-die () {
-    echo
-    echo "$*"
-    echo
-    exit 1
-}
-
-# OS specific support (must be 'true' or 'false').
-cygwin=false
-msys=false
-darwin=false
-nonstop=false
-case "`uname`" in
-  CYGWIN* )
-    cygwin=true
-    ;;
-  Darwin* )
-    darwin=true
-    ;;
-  MINGW* )
-    msys=true
-    ;;
-  NONSTOP* )
-    nonstop=true
-    ;;
-esac
-
-CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
-
-# Determine the Java command to use to start the JVM.
-if [ -n "$JAVA_HOME" ] ; then
-    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
-        # IBM's JDK on AIX uses strange locations for the executables
-        JAVACMD="$JAVA_HOME/jre/sh/java"
-    else
-        JAVACMD="$JAVA_HOME/bin/java"
-    fi
-    if [ ! -x "$JAVACMD" ] ; then
-        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
-
-Please set the JAVA_HOME variable in your environment to match the
-location of your Java installation."
-    fi
-else
-    JAVACMD="java"
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-
-Please set the JAVA_HOME variable in your environment to match the
-location of your Java installation."
-fi
-
-# Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
-    MAX_FD_LIMIT=`ulimit -H -n`
-    if [ $? -eq 0 ] ; then
-        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
-            MAX_FD="$MAX_FD_LIMIT"
-        fi
-        ulimit -n $MAX_FD
-        if [ $? -ne 0 ] ; then
-            warn "Could not set maximum file descriptor limit: $MAX_FD"
-        fi
-    else
-        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
-    fi
-fi
-
-# For Darwin, add options to specify how the application appears in the dock
-if $darwin; then
-    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
-fi
-
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
-    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
-    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
-    JAVACMD=`cygpath --unix "$JAVACMD"`
-
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
-    SEP=""
-    for dir in $ROOTDIRSRAW ; do
-        ROOTDIRS="$ROOTDIRS$SEP$dir"
-        SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
-        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
-    # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "$@" ; do
-        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
-        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
-
-        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
-            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
-        else
-            eval `echo args$i`="\"$arg\""
-        fi
-        i=$((i+1))
-    done
-    case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
-    esac
-fi
-
-# Escape application args
-save () {
-    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
-    echo " "
-}
-APP_ARGS=$(save "$@")
-
-# Collect all arguments for the java command, following the shell quoting and substitution rules
-eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
-
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
-  cd "$(dirname "$0")"
-fi
-
-exec "$JAVACMD" "$@"

core-kotlin-2/gradlew.bat

@@ -1,100 +0,0 @@
-@rem
-@rem Copyright 2015 the original author or authors.
-@rem
-@rem Licensed under the Apache License, Version 2.0 (the "License");
-@rem you may not use this file except in compliance with the License.
-@rem You may obtain a copy of the License at
-@rem
-@rem      http://www.apache.org/licenses/LICENSE-2.0
-@rem
-@rem Unless required by applicable law or agreed to in writing, software
-@rem distributed under the License is distributed on an "AS IS" BASIS,
-@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-@rem See the License for the specific language governing permissions and
-@rem limitations under the License.
-@rem
-
-@if "%DEBUG%" == "" @echo off
-@rem ##########################################################################
-@rem
-@rem  Gradle startup script for Windows
-@rem
-@rem ##########################################################################
-
-@rem Set local scope for the variables with windows NT shell
-if "%OS%"=="Windows_NT" setlocal
-
-set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
-set APP_BASE_NAME=%~n0
-set APP_HOME=%DIRNAME%
-
-@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
-
-@rem Find java.exe
-if defined JAVA_HOME goto findJavaFromJavaHome
-
-set JAVA_EXE=java.exe
-%JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto init
-
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
-
-goto fail
-
-:findJavaFromJavaHome
-set JAVA_HOME=%JAVA_HOME:"=%
-set JAVA_EXE=%JAVA_HOME%/bin/java.exe
-
-if exist "%JAVA_EXE%" goto init
-
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
-
-goto fail
-
-:init
-@rem Get command-line arguments, handling Windows variants
-
-if not "%OS%" == "Windows_NT" goto win9xME_args
-
-:win9xME_args
-@rem Slurp the command line arguments.
-set CMD_LINE_ARGS=
-set _SKIP=2
-
-:win9xME_args_slurp
-if "x%~1" == "x" goto execute
-
-set CMD_LINE_ARGS=%*
-
-:execute
-@rem Setup the command line
-
-set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
-
-@rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
-
-:end
-@rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
-
-:fail
-rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
-rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
-
-:mainEnd
-if "%OS%"=="Windows_NT" endlocal
-
-:omega

core-kotlin-2/pom.xml

@@ -1,97 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    <modelVersion>4.0.0</modelVersion>
-    <artifactId>core-kotlin-2</artifactId>
-    <name>core-kotlin-2</name>
-    <packaging>jar</packaging>
-
-    <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-kotlin</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
-        <relativePath>../parent-kotlin</relativePath>
-    </parent>
-
-    <dependencies>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-stdlib-jdk8</artifactId>
-            <version>${kotlin.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-            <version>${junit.jupiter.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.mockito</groupId>
-            <artifactId>mockito-core</artifactId>
-            <version>${mockito.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>net.bytebuddy</groupId>
-            <artifactId>byte-buddy</artifactId>
-            <version>${byte-buddy.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-test</artifactId>
-            <version>${kotlin.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-test-junit5</artifactId>
-            <version>${kotlin.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.jetbrains.kotlin</groupId>
-                <artifactId>kotlin-maven-plugin</artifactId>
-                <version>${kotlin.version}</version>
-                <executions>
-                    <execution>
-                        <id>compile</id>
-                        <phase>compile</phase>
-                        <goals>
-                            <goal>compile</goal>
-                        </goals>
-                    </execution>
-                    <execution>
-                        <id>test-compile</id>
-                        <phase>test-compile</phase>
-                        <goals>
-                            <goal>test-compile</goal>
-                        </goals>
-                    </execution>
-                </executions>
-                <configuration>
-                    <jvmTarget>1.8</jvmTarget>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
-
-    <properties>
-        <kotlin.version>1.3.30</kotlin.version>
-        <junit.jupiter.version>5.4.2</junit.jupiter.version>
-        <mockito.version>2.27.0</mockito.version>
-        <byte-buddy.version>1.9.12</byte-buddy.version>
-        <assertj.version>3.10.0</assertj.version>
-    </properties>
-
-</project>

core-kotlin-2/resources/logback.xml

@@ -1,11 +0,0 @@
-<configuration>
-  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
-    <encoder>
-      <pattern>%d{YYYY-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
-    </encoder>
-  </appender>
-
-  <root level="INFO">
-    <appender-ref ref="STDOUT"/>
-  </root>
-</configuration>

core-kotlin-2/settings.gradle

@@ -1,2 +0,0 @@
-rootProject.name = 'KtorWithKotlin'
-

core-kotlin-2/src/test/resources/Kotlin.in

@@ -1,5 +0,0 @@
-Hello to Kotlin. Its:
-1. Concise
-2. Safe
-3. Interoperable
-4. Tool-friendly

core-kotlin-2/src/test/resources/Kotlin.out

@@ -1,2 +0,0 @@
-Kotlin
-Concise, Safe, Interoperable, Tool-friendly

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

@@ -0,0 +1,8 @@
+## Core Kotlin 2
+
+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)
+- [[<-- Prev]](/core-kotlin-modules/core-kotlin)

core-kotlin-modules/core-kotlin-2/pom.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-kotlin-2</artifactId>
+    <name>core-kotlin-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-kotlin-modules</groupId>
+        <artifactId>core-kotlin-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

core-kotlin-modules/core-kotlin-2/src/main/kotlin/com/baeldung/dates/datetime/UseDuration.kt

@@ -1,4 +1,4 @@
-package com.baeldung.datetime
+package com.baeldung.dates.datetime
 
 import java.time.Duration
 import java.time.LocalTime

core-kotlin-modules/core-kotlin-2/src/main/kotlin/com/baeldung/dates/datetime/UseLocalDate.kt

@@ -1,4 +1,4 @@
-package com.baeldung.datetime
+package com.baeldung.dates.datetime
 
 import java.time.DayOfWeek
 import java.time.LocalDate

core-kotlin-modules/core-kotlin-2/src/main/kotlin/com/baeldung/dates/datetime/UseLocalDateTime.kt

@@ -1,4 +1,4 @@
-package com.baeldung.datetime
+package com.baeldung.dates.datetime
 
 import java.time.LocalDateTime
 

core-kotlin-modules/core-kotlin-2/src/main/kotlin/com/baeldung/dates/datetime/UseLocalTime.kt

@@ -1,6 +1,5 @@
-package com.baeldung.datetime
+package com.baeldung.dates.datetime
 
-import java.time.LocalDateTime
 import java.time.LocalTime
 import java.time.temporal.ChronoUnit