Fixed conflicts

algorithms-miscellaneous-1/README.md

@@ -7,8 +7,6 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 
 - [Validating Input With Finite Automata in Java](https://www.baeldung.com/java-finite-automata)
 - [Example of Hill Climbing Algorithm](https://www.baeldung.com/java-hill-climbing-algorithm)
-- [Monte Carlo Tree Search for Tic-Tac-Toe Game](https://www.baeldung.com/java-monte-carlo-tree-search)
-- [Binary Search Algorithm in Java](https://www.baeldung.com/java-binary-search)
 - [Introduction to Minimax Algorithm](https://www.baeldung.com/java-minimax-algorithm)
 - [How to Calculate Levenshtein Distance in Java?](https://www.baeldung.com/java-levenshtein-distance)
 - [How to Find the Kth Largest Element in Java](https://www.baeldung.com/java-kth-largest-element)

algorithms-miscellaneous-3/README.md

@@ -14,8 +14,6 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [A Guide to the Folding Technique in Java](https://www.baeldung.com/folding-hashing-technique)
 - [Creating a Triangle with for Loops in Java](https://www.baeldung.com/java-print-triangle)
 - [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)
-- [Interpolation Search in Java](https://www.baeldung.com/java-interpolation-search)
 - [The K-Means Clustering Algorithm in Java](https://www.baeldung.com/java-k-means-clustering-algorithm)
 - [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)
-- [Breadth-First Search Algorithm in Java](https://www.baeldung.com/java-breadth-first-search)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-2) [[next -->]](/algorithms-miscellaneous-4)

algorithms-miscellaneous-4/README.md

@@ -5,10 +5,10 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 ### Relevant articles:
 
 - [Multi-Swarm Optimization Algorithm in Java](https://www.baeldung.com/java-multi-swarm-algorithm)
-- [String Search Algorithms for Large Texts](https://www.baeldung.com/java-full-text-search-algorithms)
 - [Check If a String Contains All The Letters of The Alphabet](https://www.baeldung.com/java-string-contains-all-letters)
 - [Find the Middle Element of a Linked List](https://www.baeldung.com/java-linked-list-middle-element)
 - [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
 - [Find the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)
 - [Permutations of an Array in Java](https://www.baeldung.com/java-array-permutations)
+- [Find the Smallest Missing Integer in an Array](https://www.baeldung.com/java-smallest-missing-integer-in-array)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-3) [[next -->]](/algorithms-miscellaneous-5)

algorithms-miscellaneous-4/src/test/java/com/baeldung/algorithms/StringSearchAlgorithmsUnitTest.java

@@ -1,25 +0,0 @@
-package com.baeldung.algorithms;
-
-
-import org.junit.Assert;
-import org.junit.Test;
-
-import com.baeldung.algorithms.string.search.StringSearchAlgorithms;
-
-public class StringSearchAlgorithmsUnitTest {
-	
-	
-	@Test
-	public void testStringSearchAlgorithms(){
-		String text = "This is some nice text.";
-		String pattern = "some";
-		
-		int realPosition = text.indexOf(pattern);
-        Assert.assertTrue(realPosition == StringSearchAlgorithms.simpleTextSearch(pattern.toCharArray(), text.toCharArray()));
-        Assert.assertTrue(realPosition == StringSearchAlgorithms.RabinKarpMethod(pattern.toCharArray(), text.toCharArray()));
-        Assert.assertTrue(realPosition == StringSearchAlgorithms.KnuthMorrisPrattSearch(pattern.toCharArray(), text.toCharArray()));
-        Assert.assertTrue(realPosition == StringSearchAlgorithms.BoyerMooreHorspoolSimpleSearch(pattern.toCharArray(), text.toCharArray()));
-        Assert.assertTrue(realPosition == StringSearchAlgorithms.BoyerMooreHorspoolSearch(pattern.toCharArray(), text.toCharArray()));
-	}
-
-}

algorithms-miscellaneous-5/README.md

@@ -9,4 +9,5 @@ This module contains articles about algorithms. Some classes of algorithms, e.g.
 - [Reversing a Binary Tree in Java](https://www.baeldung.com/java-reversing-a-binary-tree)
 - [Find If Two Numbers Are Relatively Prime in Java](https://www.baeldung.com/java-two-relatively-prime-numbers)
 - [Knapsack Problem Implementation in Java](https://www.baeldung.com/java-knapsack)
+- [How to Determine if a Binary Tree is Balanced](https://www.baeldung.com/java-balanced-binary-tree)
 - More articles: [[<-- prev]](/../algorithms-miscellaneous-4)

algorithms-searching/README.md

@@ -0,0 +1,11 @@
+## Algorithms - Searching
+
+This module contains articles about searching algorithms.
+
+### Relevant articles:
+- [Binary Search Algorithm in Java](https://www.baeldung.com/java-binary-search)
+- [Depth First Search in Java](https://www.baeldung.com/java-depth-first-search)
+- [Interpolation Search in Java](https://www.baeldung.com/java-interpolation-search)
+- [Breadth-First Search Algorithm in Java](https://www.baeldung.com/java-breadth-first-search)
+- [String Search Algorithms for Large Texts](https://www.baeldung.com/java-full-text-search-algorithms)
+- [Monte Carlo Tree Search for Tic-Tac-Toe Game](https://www.baeldung.com/java-monte-carlo-tree-search)

algorithms-searching/pom.xml

@@ -0,0 +1,37 @@
+<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>algorithms-searching</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>algorithms-searching</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${org.assertj.core.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>algorithms-searching</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <org.assertj.core.version>3.9.0</org.assertj.core.version>
+    </properties>
+
+</project>

algorithms-searching/src/main/java/com/baeldung/algorithms/dfs/BinaryTree.java

@@ -0,0 +1,227 @@
+package com.baeldung.algorithms.dfs;
+
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.Stack;
+
+public class BinaryTree {
+
+    Node root;
+
+    public void add(int value) {
+        root = addRecursive(root, value);
+    }
+
+    private Node addRecursive(Node current, int value) {
+
+        if (current == null) {
+            return new Node(value);
+        }
+
+        if (value < current.value) {
+            current.left = addRecursive(current.left, value);
+        } else if (value > current.value) {
+            current.right = addRecursive(current.right, value);
+        }
+
+        return current;
+    }
+
+    public boolean isEmpty() {
+        return root == null;
+    }
+
+    public int getSize() {
+        return getSizeRecursive(root);
+    }
+
+    private int getSizeRecursive(Node current) {
+        return current == null ? 0 : getSizeRecursive(current.left) + 1 + getSizeRecursive(current.right);
+    }
+
+    public boolean containsNode(int value) {
+        return containsNodeRecursive(root, value);
+    }
+
+    private boolean containsNodeRecursive(Node current, int value) {
+        if (current == null) {
+            return false;
+        }
+
+        if (value == current.value) {
+            return true;
+        }
+
+        return value < current.value
+          ? containsNodeRecursive(current.left, value)
+          : containsNodeRecursive(current.right, value);
+    }
+
+    public void delete(int value) {
+        root = deleteRecursive(root, value);
+    }
+
+    private Node deleteRecursive(Node current, int value) {
+        if (current == null) {
+            return null;
+        }
+
+        if (value == current.value) {
+            // Case 1: no children
+            if (current.left == null && current.right == null) {
+                return null;
+            }
+
+            // Case 2: only 1 child
+            if (current.right == null) {
+                return current.left;
+            }
+
+            if (current.left == null) {
+                return current.right;
+            }
+
+            // Case 3: 2 children
+            int smallestValue = findSmallestValue(current.right);
+            current.value = smallestValue;
+            current.right = deleteRecursive(current.right, smallestValue);
+            return current;
+        }
+        if (value < current.value) {
+            current.left = deleteRecursive(current.left, value);
+            return current;
+        }
+
+        current.right = deleteRecursive(current.right, value);
+        return current;
+    }
+
+    private int findSmallestValue(Node root) {
+        return root.left == null ? root.value : findSmallestValue(root.left);
+    }
+
+    public void traverseInOrder(Node node) {
+        if (node != null) {
+            traverseInOrder(node.left);
+            visit(node.value);
+            traverseInOrder(node.right);
+        }
+    }
+
+    public void traversePreOrder(Node node) {
+        if (node != null) {
+            visit(node.value);
+            traversePreOrder(node.left);
+            traversePreOrder(node.right);
+        }
+    }
+
+    public void traversePostOrder(Node node) {
+        if (node != null) {
+            traversePostOrder(node.left);
+            traversePostOrder(node.right);
+            visit(node.value);
+        }
+    }
+
+    public void traverseLevelOrder() {
+        if (root == null) {
+            return;
+        }
+
+        Queue<Node> nodes = new LinkedList<>();
+        nodes.add(root);
+
+        while (!nodes.isEmpty()) {
+
+            Node node = nodes.remove();
+
+            System.out.print(" " + node.value);
+
+            if (node.left != null) {
+                nodes.add(node.left);
+            }
+
+            if (node.left != null) {
+                nodes.add(node.right);
+            }
+        }
+    }
+
+    
+    public void traverseInOrderWithoutRecursion() {
+        Stack<Node> stack = new Stack<Node>();
+        Node current = root;
+        stack.push(root);
+        while(! stack.isEmpty()) {
+            while(current.left != null) {
+                current = current.left;                
+                stack.push(current);                
+            }
+            current = stack.pop();
+            visit(current.value);
+            if(current.right != null) {
+                current = current.right;                
+                stack.push(current);
+            }
+        }
+    }
+    
+    public void traversePreOrderWithoutRecursion() {
+        Stack<Node> stack = new Stack<Node>();
+        Node current = root;
+        stack.push(root);
+        while(! stack.isEmpty()) {
+            current = stack.pop();
+            visit(current.value);
+            
+            if(current.right != null)
+                stack.push(current.right);
+                
+            if(current.left != null)
+                stack.push(current.left);
+        }        
+    }
+    
+    public void traversePostOrderWithoutRecursion() {
+        Stack<Node> stack = new Stack<Node>();
+        Node prev = root;
+        Node current = root;
+        stack.push(root);
+
+        while (!stack.isEmpty()) {
+            current = stack.peek();
+            boolean hasChild = (current.left != null || current.right != null);
+            boolean isPrevLastChild = (prev == current.right || (prev == current.left && current.right == null));
+
+            if (!hasChild || isPrevLastChild) {
+                current = stack.pop();
+                visit(current.value);
+                prev = current;
+            } else {
+                if (current.right != null) {
+                    stack.push(current.right);
+                }
+                if (current.left != null) {
+                    stack.push(current.left);
+                }
+            }
+        }   
+    }    
+    
+    private void visit(int value) {
+        System.out.print(" " + value);        
+    }
+    
+    class Node {
+        int value;
+        Node left;
+        Node right;
+
+        Node(int value) {
+            this.value = value;
+            right = null;
+            left = null;
+        }
+    }
+}

algorithms-searching/src/main/java/com/baeldung/algorithms/dfs/Graph.java

@@ -1,4 +1,4 @@
-package com.baeldung.graph;
+package com.baeldung.algorithms.dfs;
 
 import java.util.ArrayList;
 import java.util.HashMap;

algorithms-searching/src/main/java/com/baeldung/algorithms/textsearch/TextSearchAlgorithms.java

@@ -1,9 +1,9 @@
-package com.baeldung.algorithms.string.search;
+package com.baeldung.algorithms.textsearch;
 
 import java.math.BigInteger;
 import java.util.Random;
 
-public class StringSearchAlgorithms {
+public class TextSearchAlgorithms {
     public static long getBiggerPrime(int m) {
         BigInteger prime = BigInteger.probablePrime(getNumberOfBits(m) + 1, new Random());
         return prime.longValue();

algorithms-searching/src/main/resources/logback.xml

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

algorithms-searching/src/test/java/com/baeldung/algorithms/binarysearch/BinarySearchUnitTest.java

@@ -2,10 +2,8 @@ package com.baeldung.algorithms.binarysearch;
 
 import java.util.Arrays;
 import java.util.List;
-
 import org.junit.Assert;
 import org.junit.Test;
-import com.baeldung.algorithms.binarysearch.BinarySearch;
 
 public class BinarySearchUnitTest {
 

algorithms-searching/src/test/java/com/baeldung/algorithms/dfs/BinaryTreeUnitTest.java

@@ -0,0 +1,136 @@
+package com.baeldung.algorithms.dfs;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class BinaryTreeUnitTest {
+
+    @Test
+    public void givenABinaryTree_WhenAddingElements_ThenTreeNotEmpty() {
+
+        BinaryTree bt = createBinaryTree();
+
+        assertTrue(!bt.isEmpty());
+    }
+
+    @Test
+    public void givenABinaryTree_WhenAddingElements_ThenTreeContainsThoseElements() {
+
+        BinaryTree bt = createBinaryTree();
+
+        assertTrue(bt.containsNode(6));
+        assertTrue(bt.containsNode(4));
+
+        assertFalse(bt.containsNode(1));
+    }
+
+    @Test
+    public void givenABinaryTree_WhenAddingExistingElement_ThenElementIsNotAdded() {
+
+        BinaryTree bt = createBinaryTree();
+
+        int initialSize = bt.getSize();
+
+        assertTrue(bt.containsNode(3));
+        bt.add(3);
+        assertEquals(initialSize, bt.getSize());
+    }
+
+    @Test
+    public void givenABinaryTree_WhenLookingForNonExistingElement_ThenReturnsFalse() {
+
+        BinaryTree bt = createBinaryTree();
+
+        assertFalse(bt.containsNode(99));
+    }
+
+    @Test
+    public void givenABinaryTree_WhenDeletingElements_ThenTreeDoesNotContainThoseElements() {
+
+        BinaryTree bt = createBinaryTree();
+
+        assertTrue(bt.containsNode(9));
+        bt.delete(9);
+        assertFalse(bt.containsNode(9));
+    }
+
+    @Test
+    public void givenABinaryTree_WhenDeletingNonExistingElement_ThenTreeDoesNotDelete() {
+
+        BinaryTree bt = createBinaryTree();
+
+        int initialSize = bt.getSize();
+
+        assertFalse(bt.containsNode(99));
+        bt.delete(99);
+        assertFalse(bt.containsNode(99));
+        assertEquals(initialSize, bt.getSize());
+    }
+
+    @Test
+    public void it_deletes_the_root() {
+        int value = 12;
+        BinaryTree bt = new BinaryTree();
+        bt.add(value);
+
+        assertTrue(bt.containsNode(value));
+        bt.delete(value);
+        assertFalse(bt.containsNode(value));
+    }
+
+    @Test
+    public void givenABinaryTree_WhenTraversingInOrder_ThenPrintValues() {
+
+        BinaryTree bt = createBinaryTree();
+
+        bt.traverseInOrder(bt.root);
+        System.out.println();
+        bt.traverseInOrderWithoutRecursion();
+    }
+
+    @Test
+    public void givenABinaryTree_WhenTraversingPreOrder_ThenPrintValues() {
+
+        BinaryTree bt = createBinaryTree();
+
+        bt.traversePreOrder(bt.root);
+        System.out.println();
+        bt.traversePreOrderWithoutRecursion();
+    }
+
+    @Test
+    public void givenABinaryTree_WhenTraversingPostOrder_ThenPrintValues() {
+
+        BinaryTree bt = createBinaryTree();
+
+        bt.traversePostOrder(bt.root);
+        System.out.println();
+        bt.traversePostOrderWithoutRecursion();
+    }
+
+    @Test
+    public void givenABinaryTree_WhenTraversingLevelOrder_ThenPrintValues() {
+
+        BinaryTree bt = createBinaryTree();
+
+        bt.traverseLevelOrder();
+    }
+
+    private BinaryTree createBinaryTree() {
+        BinaryTree bt = new BinaryTree();
+
+        bt.add(6);
+        bt.add(4);
+        bt.add(8);
+        bt.add(3);
+        bt.add(5);
+        bt.add(7);
+        bt.add(9);
+
+        return bt;
+    }
+
+}

algorithms-searching/src/test/java/com/baeldung/algorithms/dfs/GraphUnitTest.java

@@ -1,7 +1,8 @@
-package com.baeldung.graph;
+package com.baeldung.algorithms.dfs;
 
 import java.util.List;
 
+import com.baeldung.algorithms.dfs.Graph;
 import org.junit.Test;
 
 public class GraphUnitTest {

algorithms-searching/src/test/java/com/baeldung/algorithms/interpolationsearch/InterpolationSearchUnitTest.java

@@ -1,10 +1,10 @@
 package com.baeldung.algorithms.interpolationsearch;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
 import org.junit.Before;
 import org.junit.Test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 public class InterpolationSearchUnitTest {
     
     private int[] myData;

algorithms-searching/src/test/java/com/baeldung/algorithms/textsearch/TextSearchAlgorithmsUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.algorithms.textsearch;
+
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TextSearchAlgorithmsUnitTest {
+
+
+    @Test
+    public void testStringSearchAlgorithms() {
+        String text = "This is some nice text.";
+        String pattern = "some";
+
+        int realPosition = text.indexOf(pattern);
+        Assert.assertTrue(realPosition == TextSearchAlgorithms.simpleTextSearch(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == TextSearchAlgorithms.RabinKarpMethod(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == TextSearchAlgorithms.KnuthMorrisPrattSearch(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == TextSearchAlgorithms.BoyerMooreHorspoolSimpleSearch(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == TextSearchAlgorithms.BoyerMooreHorspoolSearch(pattern.toCharArray(), text.toCharArray()));
+    }
+
+}

aws/src/test/java/com/baeldung/dynamodb/rule/LocalDbCreationRule.java

@@ -15,7 +15,7 @@ public class LocalDbCreationRule extends ExternalResource {
     @Override
     protected void before() throws Exception {
         String port = "8000";
-        this.server = ServerRunner.createServerFromCommandLineArgs(new String[]{"-inMemory", "-port", port});
+        this.server = ServerRunner.createServerFromCommandLineArgs(new String[]{"-inMemory","-sharedDb" ,"-port", port});
         server.start();
     }
 

code-generation/README.md

@@ -7,3 +7,4 @@ This module contains articles about automatic code generation
 - [Introduction to AutoValue](https://www.baeldung.com/introduction-to-autovalue)
 - [Introduction to AutoFactory](https://www.baeldung.com/autofactory)
 - [Google AutoService](https://www.baeldung.com/google-autoservice)
+- [Defensive Copies for Collections Using AutoValue](https://www.baeldung.com/autovalue-defensive-copies)

core-java-modules/core-java-collections-list-3/README.md

@@ -9,4 +9,5 @@ This module contains articles about the Java List collection
 - [List of Primitive Integer Values in Java](https://www.baeldung.com/java-list-primitive-int)
 - [Performance Comparison of Primitive Lists in Java](https://www.baeldung.com/java-list-primitive-performance)
 - [Filtering a Java Collection by a List](https://www.baeldung.com/java-filter-collection-by-list)
+- [How to Count Duplicate Elements in Arraylist](https://www.baeldung.com/java-count-duplicate-elements-arraylist)
 - [[<-- Prev]](/core-java-modules/core-java-collections-list-2)

core-java-modules/core-java-concurrency-advanced-3/pom.xml

@@ -14,11 +14,18 @@
         <relativePath>../../parent-java</relativePath>
     </parent>
 
-    <dependencies>
-    </dependencies>
-
     <build>
         <finalName>core-java-concurrency-advanced-3</finalName>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
         <resources>
             <resource>
                 <directory>src/main/resources</directory>
@@ -28,6 +35,8 @@
     </build>
 
     <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
     </properties>
 
 </project>

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/CollectionsConcurrencyIssues.java

@@ -0,0 +1,53 @@
+package com.baeldung.commonissues;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class CollectionsConcurrencyIssues {
+
+    private void putIfAbsentList_NonAtomicOperation_ProneToConcurrencyIssues() {
+        List<String> list = Collections.synchronizedList(new ArrayList<>());
+        if (!list.contains("foo")) {
+            list.add("foo");
+        }
+    }
+
+    private void putIfAbsentList_AtomicOperation_ThreadSafe() {
+        List<String> list = Collections.synchronizedList(new ArrayList<>());
+        synchronized (list) {
+            if (!list.contains("foo")) {
+                list.add("foo");
+            }
+        }
+    }
+
+    private void putIfAbsentMap_NonAtomicOperation_ProneToConcurrencyIssues() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        if (!map.containsKey("foo")) {
+            map.put("foo", "bar");
+        }
+    }
+
+    private void putIfAbsentMap_AtomicOperation_BetterApproach() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        synchronized (map) {
+            if (!map.containsKey("foo")) {
+                map.put("foo", "bar");
+            }
+        }
+    }
+
+    private void putIfAbsentMap_AtomicOperation_BestApproach() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        map.putIfAbsent("foo", "bar");
+    }
+
+    private void computeIfAbsentMap_AtomicOperation() {
+        Map<String, String> map = new ConcurrentHashMap<>();
+        map.computeIfAbsent("foo", key -> key + "bar");
+    }
+
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/Counter.java

@@ -0,0 +1,13 @@
+package com.baeldung.commonissues;
+
+class Counter {
+    private int counter = 0;
+
+    public void increment() {
+        counter++;
+    }
+
+    public int getValue() {
+        return counter;
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/DeadlockExample.java

@@ -0,0 +1,42 @@
+package com.baeldung.commonissues;
+
+public class DeadlockExample {
+
+    public static Object lock1 = new Object();
+    public static Object lock2 = new Object();
+
+    public static void main(String args[]) {
+        Thread threadA = new Thread(() -> {
+            synchronized (lock1) {
+                System.out.println("ThreadA: Holding lock 1...");
+                sleep();
+                System.out.println("ThreadA: Waiting for lock 2...");
+
+                synchronized (lock2) {
+                    System.out.println("ThreadA: Holding lock 1 & 2...");
+                }
+            }
+        });
+        Thread threadB = new Thread(() -> {
+            synchronized (lock2) {
+                System.out.println("ThreadB: Holding lock 2...");
+                sleep();
+                System.out.println("ThreadB: Waiting for lock 1...");
+
+                synchronized (lock1) {
+                    System.out.println("ThreadB: Holding lock 1 & 2...");
+                }
+            }
+        });
+        threadA.start();
+        threadB.start();
+    }
+
+    private static void sleep() {
+        try {
+            Thread.sleep(100);
+        } catch (InterruptedException e) {
+            throw new RuntimeException();
+        }
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/SimpleDateFormatThreadUnsafetyExample.java

@@ -0,0 +1,35 @@
+package com.baeldung.commonissues;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class SimpleDateFormatThreadUnsafetyExample {
+
+    private static SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+
+    public static void main(String[] args) {
+        String dateStr = "2019-10-29T11:12:21";
+
+        ExecutorService executorService = Executors.newFixedThreadPool(10);
+
+        for (int i = 0; i < 20; i++) {
+            executorService.submit(() -> parseDate(dateStr));
+        }
+
+        executorService.shutdown();
+    }
+
+    private static void parseDate(String dateStr) {
+        try {
+            Date date = simpleDateFormat.parse(dateStr);
+            System.out.println("Successfully Parsed Date " + date);
+        } catch (ParseException e) {
+            System.out.println("ParseError " + e.getMessage());
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/SynchronizedCounter.java

@@ -0,0 +1,13 @@
+package com.baeldung.commonissues;
+
+class SynchronizedCounter {
+    private int counter = 0;
+
+    public synchronized void increment() {
+        counter++;
+    }
+
+    public synchronized int getValue() {
+        return counter;
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/commonissues/SynchronizedVolatileCounter.java

@@ -0,0 +1,13 @@
+package com.baeldung.commonissues;
+
+class SynchronizedVolatileCounter {
+    private volatile int counter = 0;
+
+    public synchronized void increment() {
+        counter++;
+    }
+
+    public int getValue() {
+        return counter;
+    }
+}

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

@@ -0,0 +1,3 @@
+### Relevant Articles:
+- [Get the Current Date Prior to Java 8](https://www.baeldung.com/java-get-the-current-date-legacy)
+- [Skipping Weekends While Adding Days to LocalDate in Java 8](https://www.baeldung.com/java-localdate-add-days-skip-weekends)

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

@@ -13,3 +13,4 @@ This module contains articles about the Date and Time API introduced with Java 8
 - [How to Get the Start and the End of a Day using Java](http://www.baeldung.com/java-day-start-end)
 - [Set the Time Zone of a Date in Java](https://www.baeldung.com/java-set-date-time-zone)
 - [Comparing Dates in Java](https://www.baeldung.com/java-comparing-dates)
+- [Generating Random Dates in Java](https://www.baeldung.com/java-random-dates)

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

@@ -17,3 +17,4 @@ This module contains articles about core java exceptions
 - [Common Java Exceptions](https://www.baeldung.com/java-common-exceptions)
 - [Throw Exception in Optional in Java 8](https://www.baeldung.com/java-optional-throw-exception)
 - [How to Find an Exception’s Root Cause in Java](https://www.baeldung.com/java-exception-root-cause)
+- [Is It a Bad Practice to Catch Throwable?](https://www.baeldung.com/java-catch-throwable-bad-practice)

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

@@ -5,4 +5,5 @@ This module contains articles about core features in the Java language
 ### Relevant Articles: 
 - [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)
 - [[<-- Prev]](/core-java-modules/core-java-lang)

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

@@ -6,3 +6,4 @@
 - [Java 8 Math New Methods](https://www.baeldung.com/java-8-math)
 - [Java 8 Unsigned Arithmetic Support](https://www.baeldung.com/java-unsigned-arithmetic)
 - [How to Separate Double into Integer and Decimal Parts](https://www.baeldung.com/java-separate-double-into-integer-decimal-parts)
+- [The strictfp Keyword in Java](https://www.baeldung.com/java-strictfp)

core-java-modules/core-java-lang-math/src/main/java/com/baeldung/calculator/basic/BasicCalculatorIfElse.java

@@ -0,0 +1,50 @@
+package com.baeldung.calculator.basic;
+
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class BasicCalculatorIfElse {
+
+    public static void main(String[] args) {
+
+        System.out.println("---------------------------------- \n" + "Welcome to Basic Calculator \n" + "----------------------------------");
+        System.out.println("Following operations are supported : \n" + "1. Addition (+) \n" + "2. Subtraction (-) \n" + "3. Multiplication (* OR x) \n" + "4. Division (/) \n");
+
+        Scanner scanner = new Scanner(System.in);
+        try {
+            System.out.println("Enter an operator: (+ OR - OR * OR /) ");
+            char operation = scanner.next()
+                .charAt(0);
+
+            if (!(operation == '+' || operation == '-' || operation == '*' || operation == 'x' || operation == '/')) {
+                System.err.println("Invalid Operator. Please use only + or - or * or /");
+            }
+
+            System.out.println("Enter First Number: ");
+            double num1 = scanner.nextDouble();
+
+            System.out.println("Enter Second Number: ");
+            double num2 = scanner.nextDouble();
+
+            if (operation == '/' && num2 == 0.0) {
+                System.err.println("Second Number cannot be zero for Division operation.");
+            }
+
+            if (operation == '+') {
+                System.out.println(num1 + " + " + num2 + " = " + (num1 + num2));
+            } else if (operation == '-') {
+                System.out.println(num1 + " - " + num2 + " = " + (num1 - num2));
+            } else if (operation == '*' || operation == 'x') {
+                System.out.println(num1 + " x " + num2 + " = " + (num1 * num2));
+            } else if (operation == '/') {
+                System.out.println(num1 + " / " + num2 + " = " + (num1 / num2));
+            } else {
+                System.err.println("Invalid Operator Specified.");
+            }
+        } catch (InputMismatchException exc) {
+            System.err.println(exc.getMessage());
+        } finally {
+            scanner.close();
+        }
+    }
+}

core-java-modules/core-java-lang-math/src/main/java/com/baeldung/calculator/basic/BasicCalculatorSwitchCase.java

@@ -0,0 +1,58 @@
+package com.baeldung.calculator.basic;
+
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class BasicCalculatorSwitchCase {
+    public static void main(String[] args) {
+
+        System.out.println("---------------------------------- \n" + "Welcome to Basic Calculator \n" + "----------------------------------");
+        System.out.println("Following operations are supported : \n" + "1. Addition (+) \n" + "2. Subtraction (-) \n" + "3. Multiplication (* OR x) \n" + "4. Division (/) \n");
+
+        Scanner scanner = new Scanner(System.in);
+        try {
+            System.out.println("Enter an operator: (+ OR - OR * OR /) ");
+            char operation = scanner.next()
+                .charAt(0);
+
+            if (!(operation == '+' || operation == '-' || operation == '*' || operation == 'x' || operation == '/')) {
+                System.err.println("Invalid Operator. Please use only + or - or * or /");
+            }
+
+            System.out.println("Enter First Number: ");
+            double num1 = scanner.nextDouble();
+
+            System.out.println("Enter Second Number: ");
+            double num2 = scanner.nextDouble();
+
+            if (operation == '/' && num2 == 0.0) {
+                System.err.println("Second Number cannot be zero for Division operation.");
+            }
+
+            switch (operation) {
+            case '+':
+                System.out.println(num1 + " + " + num2 + " = " + (num1 + num2));
+                break;
+            case '-':
+                System.out.println(num1 + " - " + num2 + " = " + (num1 - num2));
+                break;
+            case '*':
+                System.out.println(num1 + " x " + num2 + " = " + (num1 * num2));
+                break;
+            case 'x':
+                System.out.println(num1 + " x " + num2 + " = " + (num1 * num2));
+                break;
+            case '/':
+                System.out.println(num1 + " / " + num2 + " = " + (num1 / num2));
+                break;
+            default:
+                System.err.println("Invalid Operator Specified.");
+                break;
+            }
+        } catch (InputMismatchException exc) {
+            System.err.println(exc.getMessage());
+        } finally {
+            scanner.close();
+        }
+    }
+}

core-java-modules/core-java-lang-math/src/main/java/com/baeldung/overflow/Overflow.java

@@ -0,0 +1,70 @@
+package com.baeldung.overflow;
+
+import java.math.BigInteger;
+
+public class Overflow {
+
+    public static void showIntegerOverflow() {
+
+        int value = Integer.MAX_VALUE-1;
+
+        for(int i = 0; i < 4; i++, value++) {
+            System.out.println(value);
+        }
+    }
+
+    public static void noOverflowWithBigInteger() {
+
+        BigInteger largeValue = new BigInteger(Integer.MAX_VALUE + "");
+        for(int i = 0; i < 4; i++) {
+            System.out.println(largeValue);
+            largeValue = largeValue.add(BigInteger.ONE);
+        }
+    }
+
+    public static void exceptionWithAddExact() {
+
+        int value = Integer.MAX_VALUE-1;
+        for(int i = 0; i < 4; i++) {
+            System.out.println(value);
+            value = Math.addExact(value, 1);
+        }
+    }
+
+    public static int addExact(int x, int y) {
+
+        int r = x + y;
+        if (((x ^ r) & (y ^ r)) < 0) {
+            throw new ArithmeticException("int overflow");
+        }
+        return r;
+    }
+
+    public static void demonstrateUnderflow() {
+
+        for(int i = 1073; i <= 1076; i++) {
+            System.out.println("2^" + i + " = " + Math.pow(2, -i));
+        }
+    }
+
+    public static double powExact(double base, double exponent)
+    {
+        if(base == 0.0) {
+            return 0.0;
+        }
+
+        double result = Math.pow(base, exponent);
+
+        if(result == Double.POSITIVE_INFINITY ) {
+            throw new ArithmeticException("Double overflow resulting in POSITIVE_INFINITY");
+        } else if(result == Double.NEGATIVE_INFINITY) {
+            throw new ArithmeticException("Double overflow resulting in NEGATIVE_INFINITY");
+        } else if(Double.compare(-0.0f, result) == 0) {
+            throw new ArithmeticException("Double overflow resulting in negative zero");
+        } else if(Double.compare(+0.0f, result) == 0) {
+            throw new ArithmeticException("Double overflow resulting in positive zero");
+        }
+
+        return result;
+    }
+}

core-java-modules/core-java-lang-math/src/test/java/com/baeldung/math/OverflowUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.math;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class OverflowUnitTest {
+
+    @Test
+    public void positive_and_negative_zero_are_not_always_equal() {
+
+        double a = +0f;
+        double b = -0f;
+
+        assertTrue(a == b);
+
+        assertTrue(1/a == Double.POSITIVE_INFINITY);
+        assertTrue(1/b == Double.NEGATIVE_INFINITY);
+
+        assertTrue(1/a != 1/b);
+    }
+}

core-java-modules/core-java-streams-3/README.md

@@ -8,4 +8,5 @@ This module contains articles about the Stream API in Java.
 - [The Difference Between Collection.stream().forEach() and Collection.forEach()](https://www.baeldung.com/java-collection-stream-foreach)
 - [Guide to Java 8’s Collectors](https://www.baeldung.com/java-8-collectors)
 - [Primitive Type Streams in Java 8](https://www.baeldung.com/java-8-primitive-streams)
+- [Debugging Java 8 Streams with IntelliJ](https://www.baeldung.com/intellij-debugging-java-streams)
 - More articles: [[<-- prev>]](/../core-java-streams-2)

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

@@ -58,7 +58,7 @@
     </build>
 
     <properties>
-        <commons-lang3.version>3.8.1</commons-lang3.version>
+        <commons-lang3.version>3.9</commons-lang3.version>
         <assertj.version>3.6.1</assertj.version>
         <commons-codec.version>1.10</commons-codec.version>
     </properties>

core-java-modules/core-java-string-operations/src/main/java/com/baeldung/isnumeric/Benchmarking.java

@@ -1,6 +1,9 @@
 package com.baeldung.isnumeric;
 
+import java.util.HashMap;
+import java.util.Map;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
 
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
@@ -14,6 +17,8 @@ import org.openjdk.jmh.runner.options.Options;
 import org.openjdk.jmh.runner.options.OptionsBuilder;
 
 public class Benchmarking {
+    private static final TestMode MODE = TestMode.DIVERS;
+
     public static void main(String[] args) throws RunnerException {
         Options opt = new OptionsBuilder().include(Benchmarking.class.getSimpleName())
             .forks(1)
@@ -22,52 +27,89 @@ public class Benchmarking {
         new Runner(opt).run();
     }
 
+    private static final IsNumeric subject = new IsNumeric();
+
     @State(Scope.Thread)
     public static class ExecutionPlan {
-        public String number = Integer.toString(Integer.MAX_VALUE);
-        public boolean isNumber = false;
-        public IsNumeric isNumeric = new IsNumeric();
+        private final Map<String, Boolean> testPlan = testPlan();
+
+        void validate(Function<String, Boolean> functionUnderTest) {
+            testPlan.forEach((key, value) -> {
+                Boolean result = functionUnderTest.apply(key);
+
+                assertEquals(value, result, key);
+            });
+        }
+
+        private void assertEquals(Boolean expectedResult, Boolean result, String input) {
+            if (result != expectedResult) {
+                throw new IllegalStateException("The output does not match the expected output, for input: " + input);
+            }
+        }
+
+        private Map<String, Boolean> testPlan() {
+            HashMap<String, Boolean> plan = new HashMap<>();
+            plan.put(Integer.toString(Integer.MAX_VALUE), true);
+
+            if (MODE == TestMode.SIMPLE) {
+                return plan;
+            }
+
+            plan.put("x0", false);
+            plan.put("0..005", false);
+            plan.put("--11", false);
+            plan.put("test", false);
+            plan.put(null, false);
+            for (int i = 0; i < 94; i++) {
+                plan.put(Integer.toString(i), true);
+            }
+            return plan;
+        }
     }
 
     @Benchmark
     @BenchmarkMode(Mode.AverageTime)
     @OutputTimeUnit(TimeUnit.NANOSECONDS)
     public void usingCoreJava(ExecutionPlan plan) {
-        plan.isNumber = plan.isNumeric.usingCoreJava(plan.number);
+        plan.validate(subject::usingCoreJava);
     }
 
     @Benchmark
     @BenchmarkMode(Mode.AverageTime)
     @OutputTimeUnit(TimeUnit.NANOSECONDS)
     public void usingRegularExpressions(ExecutionPlan plan) {
-        plan.isNumber = plan.isNumeric.usingRegularExpressions(plan.number);
+        plan.validate(subject::usingPreCompiledRegularExpressions);
     }
 
     @Benchmark
     @BenchmarkMode(Mode.AverageTime)
     @OutputTimeUnit(TimeUnit.NANOSECONDS)
     public void usingNumberUtils_isCreatable(ExecutionPlan plan) {
-        plan.isNumber = plan.isNumeric.usingNumberUtils_isCreatable(plan.number);
+        plan.validate(subject::usingNumberUtils_isCreatable);
     }
 
     @Benchmark
     @BenchmarkMode(Mode.AverageTime)
     @OutputTimeUnit(TimeUnit.NANOSECONDS)
     public void usingNumberUtils_isParsable(ExecutionPlan plan) {
-        plan.isNumber = plan.isNumeric.usingNumberUtils_isParsable(plan.number);
+        plan.validate(subject::usingNumberUtils_isParsable);
     }
 
     @Benchmark
     @BenchmarkMode(Mode.AverageTime)
     @OutputTimeUnit(TimeUnit.NANOSECONDS)
     public void usingStringUtils_isNumeric(ExecutionPlan plan) {
-        plan.isNumber = plan.isNumeric.usingStringUtils_isNumeric(plan.number);
+        plan.validate(subject::usingStringUtils_isNumeric);
     }
 
     @Benchmark
     @BenchmarkMode(Mode.AverageTime)
     @OutputTimeUnit(TimeUnit.NANOSECONDS)
     public void usingStringUtils_isNumericSpace(ExecutionPlan plan) {
-        plan.isNumber = plan.isNumeric.usingStringUtils_isNumericSpace(plan.number);
+        plan.validate(subject::usingStringUtils_isNumericSpace);
+    }
+
+    private enum TestMode {
+        SIMPLE, DIVERS
     }
 }

core-java-modules/core-java-string-operations/src/main/java/com/baeldung/isnumeric/CheckIntegerInput.java

@@ -1,18 +0,0 @@
-package com.baeldung.isnumeric;
-
-import java.util.Scanner;
-
-public class CheckIntegerInput {
-
-    public static void main(String[] args) {
-        try (Scanner scanner = new Scanner(System.in)) {
-            System.out.println("Enter an integer : ");
-
-            if (scanner.hasNextInt()) {
-                System.out.println("You entered : " + scanner.nextInt());
-            } else {
-                System.out.println("The input is not an integer");
-            }
-        }
-    }
-}

core-java-modules/core-java-string-operations/src/main/java/com/baeldung/isnumeric/IsNumeric.java

@@ -1,20 +1,33 @@
 package com.baeldung.isnumeric;
 
+import java.util.regex.Pattern;
+
 import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.lang3.math.NumberUtils;
 
 public class IsNumeric {
+    private final Pattern pattern = Pattern.compile("-?\\d+(\\.\\d+)?");
+
     public boolean usingCoreJava(String strNum) {
+        if (strNum == null) {
+            return false;
+        }
+
         try {
             Double.parseDouble(strNum);
-        } catch (NumberFormatException | NullPointerException nfe) {
+        } catch (NumberFormatException nfe) {
             return false;
         }
         return true;
     }
 
-    public boolean usingRegularExpressions(String strNum) {
-        return strNum.matches("-?\\d+(\\.\\d+)?");
+    public boolean usingPreCompiledRegularExpressions(String strNum) {
+        if (strNum == null) {
+            return false;
+        }
+
+        return pattern.matcher(strNum)
+            .matches();
     }
 
     public boolean usingNumberUtils_isCreatable(String strNum) {

core-java-modules/core-java-string-operations/src/main/java/com/baeldung/isnumeric/IsNumericDriver.java

@@ -13,8 +13,8 @@ public class IsNumericDriver {
         boolean res = isNumeric.usingCoreJava("1001");
         LOG.info("Using Core Java : " + res);
 
-        res = isNumeric.usingRegularExpressions("1001");
-        LOG.info("Using Regular Expressions : " + res);
+        res = isNumeric.usingPreCompiledRegularExpressions("1001");
+        LOG.info("Using Pre-compiled Regular Expressions : " + res);
 
         res = isNumeric.usingNumberUtils_isCreatable("1001");
         LOG.info("Using NumberUtils.isCreatable : " + res);

core-java-modules/core-java-string-operations/src/test/java/com/baeldung/isnumeric/CoreJavaIsNumericUnitTest.java

@@ -6,9 +6,13 @@ import org.junit.Test;
 
 public class CoreJavaIsNumericUnitTest {
     public static boolean isNumeric(String strNum) {
+        if (strNum == null) {
+            return false;
+        }
+
         try {
-            double d = Double.parseDouble(strNum);
-        } catch (NumberFormatException | NullPointerException nfe) {
+            Double.parseDouble(strNum);
+        } catch (NumberFormatException nfe) {
             return false;
         }
         return true;

core-java-modules/core-java-string-operations/src/test/java/com/baeldung/isnumeric/RegularExpressionsUnitTest.java

@@ -2,11 +2,19 @@ package com.baeldung.isnumeric;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+import java.util.regex.Pattern;
+
 import org.junit.Test;
 
 public class RegularExpressionsUnitTest {
-    public static boolean isNumeric(String strNum) {
-        return strNum.matches("-?\\d+(\\.\\d+)?");
+    private final Pattern pattern = Pattern.compile("-?\\d+(\\.\\d+)?");
+
+    public boolean isNumeric(String strNum) {
+        if (strNum == null) {
+            return false;
+        }
+        return pattern.matcher(strNum)
+            .matches();
     }
 
     @Test
@@ -17,6 +25,7 @@ public class RegularExpressionsUnitTest {
         assertThat(isNumeric("-200")).isTrue();
 
         // Invalid Numbers
+        assertThat(isNumeric(null)).isFalse();
         assertThat(isNumeric("abc")).isFalse();
     }
 }

data-structures/README.md

@@ -6,4 +6,3 @@ This module contains articles about data structures in Java
 
 - [The Trie Data Structure in Java](https://www.baeldung.com/trie-java)
 - [Implementing a Binary Tree in Java](https://www.baeldung.com/java-binary-tree)
-- [Depth First Search in Java](https://www.baeldung.com/java-depth-first-search)

jackson-2/pom.xml

@@ -14,14 +14,6 @@
 
     <dependencies>
 
-        <!-- marshalling -->
-
-        <dependency>
-            <groupId>com.fasterxml.jackson.core</groupId>
-            <artifactId>jackson-databind</artifactId>
-            <version>${jackson.version}</version>
-        </dependency>
-
         <!-- YAML -->
         <dependency>
             <groupId>com.fasterxml.jackson.dataformat</groupId>

jackson-annotations/README.md

@@ -0,0 +1,11 @@
+## Jackson Annotations
+
+This module contains articles about Jackson annotations.
+
+### Relevant Articles: 
+- [Guide to @JsonFormat in Jackson](https://www.baeldung.com/jackson-jsonformat)
+- [More Jackson Annotations](https://www.baeldung.com/jackson-advanced-annotations)
+- [Jackson Annotation Examples](https://www.baeldung.com/jackson-annotations)
+- [Jackson – Bidirectional Relationships](https://www.baeldung.com/jackson-bidirectional-relationships-and-infinite-recursion)
+- [Jackson – Change Name of Field](https://www.baeldung.com/jackson-name-of-property)
+- [Jackson Ignore Properties on Marshalling](https://www.baeldung.com/jackson-ignore-properties-on-serialization)

jackson-annotations/pom.xml

@@ -0,0 +1,60 @@
+<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>jackson-annotations</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>jackson-annotations</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.dataformat</groupId>
+            <artifactId>jackson-dataformat-xml</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.module</groupId>
+            <artifactId>jackson-module-jsonSchema</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.rest-assured</groupId>
+            <artifactId>json-path</artifactId>
+            <version>${rest-assured.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>jackson-annotations</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <assertj.version>3.11.0</assertj.version>
+        <rest-assured.version>3.1.1</rest-assured.version>
+    </properties>
+
+</project>

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/bidirection/ItemWithIdentity.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.bidirection;
+package com.baeldung.jackson.annotation.bidirection;
 
 import com.fasterxml.jackson.annotation.JsonIdentityInfo;
 import com.fasterxml.jackson.annotation.ObjectIdGenerators;

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/bidirection/ItemWithIgnore.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.bidirection;
+package com.baeldung.jackson.annotation.bidirection;
 
 public class ItemWithIgnore {
     public int id;

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/bidirection/ItemWithRef.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.bidirection;
+package com.baeldung.jackson.annotation.bidirection;
 
 import com.fasterxml.jackson.annotation.JsonManagedReference;
 

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/bidirection/UserWithIdentity.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.bidirection;
+package com.baeldung.jackson.annotation.bidirection;
 
 import java.util.ArrayList;
 import java.util.List;

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/bidirection/UserWithIgnore.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.bidirection;
+package com.baeldung.jackson.annotation.bidirection;
 
 import java.util.ArrayList;
 import java.util.List;

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/bidirection/UserWithRef.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.bidirection;
+package com.baeldung.jackson.annotation.bidirection;
 
 import java.util.ArrayList;
 import java.util.List;

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/date/CustomDateDeserializer.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.date;
+package com.baeldung.jackson.annotation.date;
 
 import java.io.IOException;
 import java.text.ParseException;

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/date/CustomDateSerializer.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.date;
+package com.baeldung.jackson.annotation.date;
 
 import java.io.IOException;
 import java.text.SimpleDateFormat;

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/date/EventWithFormat.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.date;
+package com.baeldung.jackson.annotation.date;
 
 import java.util.Date;
 

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/date/EventWithSerializer.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.date;
+package com.baeldung.jackson.annotation.date;
 
 import java.util.Date;
 

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/deserialization/ItemDeserializerOnClass.java

@@ -0,0 +1,41 @@
+package com.baeldung.jackson.annotation.deserialization;
+
+import java.io.IOException;
+
+import com.baeldung.jackson.annotation.dtos.ItemWithSerializer;
+import com.baeldung.jackson.annotation.dtos.User;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
+import com.fasterxml.jackson.databind.node.IntNode;
+
+public class ItemDeserializerOnClass extends StdDeserializer<ItemWithSerializer> {
+
+    private static final long serialVersionUID = 5579141241817332594L;
+
+    public ItemDeserializerOnClass() {
+        this(null);
+    }
+
+    public ItemDeserializerOnClass(final Class<?> vc) {
+        super(vc);
+    }
+
+    /**
+     * {"id":1,"itemNr":"theItem","owner":2}
+     */
+    @Override
+    public ItemWithSerializer deserialize(final JsonParser jp, final DeserializationContext ctxt) throws IOException, JsonProcessingException {
+        final JsonNode node = jp.getCodec()
+            .readTree(jp);
+        final int id = (Integer) ((IntNode) node.get("id")).numberValue();
+        final String itemName = node.get("itemName")
+            .asText();
+        final int userId = (Integer) ((IntNode) node.get("owner")).numberValue();
+
+        return new ItemWithSerializer(id, itemName, new User(userId, null));
+    }
+
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/dtos/Item.java

@@ -0,0 +1,32 @@
+package com.baeldung.jackson.annotation.dtos;
+
+public class Item {
+    public int id;
+    public String itemName;
+    public User owner;
+
+    public Item() {
+        super();
+    }
+
+    public Item(final int id, final String itemName, final User owner) {
+        this.id = id;
+        this.itemName = itemName;
+        this.owner = owner;
+    }
+
+    // API
+
+    public int getId() {
+        return id;
+    }
+
+    public String getItemName() {
+        return itemName;
+    }
+
+    public User getOwner() {
+        return owner;
+    }
+
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/dtos/ItemWithSerializer.java

@@ -0,0 +1,36 @@
+package com.baeldung.jackson.annotation.dtos;
+
+import com.baeldung.jackson.annotation.deserialization.ItemDeserializerOnClass;
+import com.baeldung.jackson.annotation.serialization.ItemSerializerOnClass;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+
+@JsonSerialize(using = ItemSerializerOnClass.class)
+@JsonDeserialize(using = ItemDeserializerOnClass.class)
+public class ItemWithSerializer {
+    public final int id;
+    public final String itemName;
+    public final User owner;
+
+    public ItemWithSerializer(final int id, final String itemName, final User owner) {
+        this.id = id;
+        this.itemName = itemName;
+        this.owner = owner;
+    }
+
+    // API
+
+    public int getId() {
+        return id;
+    }
+
+    public String getItemName() {
+        return itemName;
+    }
+
+    public User getOwner() {
+        return owner;
+    }
+
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/dtos/User.java

@@ -0,0 +1,26 @@
+package com.baeldung.jackson.annotation.dtos;
+
+public class User {
+    public int id;
+    public String name;
+
+    public User() {
+        super();
+    }
+
+    public User(final int id, final String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    // API
+
+    public int getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/dtos/withEnum/DistanceEnumWithValue.java

@@ -0,0 +1,29 @@
+package com.baeldung.jackson.annotation.dtos.withEnum;
+
+import com.fasterxml.jackson.annotation.JsonValue;
+
+public enum DistanceEnumWithValue {
+    KILOMETER("km", 1000), MILE("miles", 1609.34), METER("meters", 1), INCH("inches", 0.0254), CENTIMETER("cm", 0.01), MILLIMETER("mm", 0.001);
+
+    private String unit;
+    private final double meters;
+
+    private DistanceEnumWithValue(String unit, double meters) {
+        this.unit = unit;
+        this.meters = meters;
+    }
+
+    @JsonValue
+    public double getMeters() {
+        return meters;
+    }
+
+    public String getUnit() {
+        return unit;
+    }
+
+    public void setUnit(String unit) {
+        this.unit = unit;
+    }
+
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/exception/UserWithRoot.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.exception;
+package com.baeldung.jackson.annotation.exception;
 
 import com.fasterxml.jackson.annotation.JsonRootName;
 

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/exception/UserWithRootNamespace.java

@@ -1,4 +1,4 @@
-package com.baeldung.jackson.exception;
+package com.baeldung.jackson.annotation.exception;
 
 import com.fasterxml.jackson.annotation.JsonRootName;
 

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/jsonview/Item.java

@@ -0,0 +1,36 @@
+package com.baeldung.jackson.annotation.jsonview;
+
+import com.fasterxml.jackson.annotation.JsonView;
+
+public class Item {
+    @JsonView(Views.Public.class)
+    public int id;
+
+    @JsonView(Views.Public.class)
+    public String itemName;
+
+    @JsonView(Views.Internal.class)
+    public String ownerName;
+
+    public Item() {
+        super();
+    }
+
+    public Item(final int id, final String itemName, final String ownerName) {
+        this.id = id;
+        this.itemName = itemName;
+        this.ownerName = ownerName;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getItemName() {
+        return itemName;
+    }
+
+    public String getOwnerName() {
+        return ownerName;
+    }
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/jsonview/Views.java

@@ -0,0 +1,9 @@
+package com.baeldung.jackson.annotation.jsonview;
+
+public class Views {
+    public static class Public {
+    }
+
+    public static class Internal extends Public {
+    }
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/serialization/ItemSerializer.java

@@ -0,0 +1,32 @@
+package com.baeldung.jackson.annotation.serialization;
+
+import java.io.IOException;
+
+import com.baeldung.jackson.annotation.dtos.Item;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.ser.std.StdSerializer;
+
+public class ItemSerializer extends StdSerializer<Item> {
+
+    private static final long serialVersionUID = 6739170890621978901L;
+
+    public ItemSerializer() {
+        this(null);
+    }
+
+    public ItemSerializer(final Class<Item> t) {
+        super(t);
+    }
+
+    @Override
+    public final void serialize(final Item value, final JsonGenerator jgen, final SerializerProvider provider) throws IOException, JsonProcessingException {
+        jgen.writeStartObject();
+        jgen.writeNumberField("id", value.id);
+        jgen.writeStringField("itemName", value.itemName);
+        jgen.writeNumberField("owner", value.owner.id);
+        jgen.writeEndObject();
+    }
+
+}

jackson-annotations/src/main/java/com/baeldung/jackson/annotation/serialization/ItemSerializerOnClass.java

@@ -0,0 +1,32 @@
+package com.baeldung.jackson.annotation.serialization;
+
+import java.io.IOException;
+
+import com.baeldung.jackson.annotation.dtos.ItemWithSerializer;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.ser.std.StdSerializer;
+
+public class ItemSerializerOnClass extends StdSerializer<ItemWithSerializer> {
+
+    private static final long serialVersionUID = -1760959597313610409L;
+
+    public ItemSerializerOnClass() {
+        this(null);
+    }
+
+    public ItemSerializerOnClass(final Class<ItemWithSerializer> t) {
+        super(t);
+    }
+
+    @Override
+    public final void serialize(final ItemWithSerializer value, final JsonGenerator jgen, final SerializerProvider provider) throws IOException, JsonProcessingException {
+        jgen.writeStartObject();
+        jgen.writeNumberField("id", value.id);
+        jgen.writeStringField("itemName", value.itemName);
+        jgen.writeNumberField("owner", value.owner.id);
+        jgen.writeEndObject();
+    }
+
+}