Merge branch 'master' into BAEL-10229

akka-http/README.md

@@ -1,3 +1,7 @@
-## Relevant articles:
+## Akka HTTP
+
+This module contains articles about Akka HTTP. 
+
+### Relevant articles:
 
 - [Introduction to Akka HTTP](https://www.baeldung.com/akka-http)

akka-streams/README.md

@@ -1,3 +1,7 @@
+## Akka Streams
+
+This module contains articles about Akka Streams. 
+
 ### Relevant articles
 
 - [Guide to Akka Streams](https://www.baeldung.com/akka-streams)

algorithms-genetic/README.md

@@ -1,4 +1,8 @@
-## Relevant articles:
+## Genetic Algorithms
+
+This module contains articles about genetic algorithms. 
+
+### Relevant articles:
 
 - [Introduction to Jenetics Library](https://www.baeldung.com/jenetics)
 - [Ant Colony Optimization](https://www.baeldung.com/java-ant-colony-optimization)

algorithms-miscellaneous-1/README.md

@@ -1,4 +1,9 @@
-## Relevant articles:
+## Algorithms - Miscellaneous
+
+This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](/../algorithms-sorting) and
+[genetic algorithms](/../algorithms-genetic), have their own dedicated modules. 
+
+### Relevant articles:
 
 - [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)
@@ -6,4 +11,5 @@
 - [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)
+- [How to Find the Kth Largest Element in Java](https://www.baeldung.com/java-kth-largest-element)
+- More articles: [[next -->]](/../algorithms-miscellaneous-2)

algorithms-miscellaneous-2/README.md

@@ -1,4 +1,9 @@
-## Relevant articles:
+## Algorithms - Miscellaneous
+
+This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](/../algorithms-sorting) and
+[genetic algorithms](/../algorithms-genetic), have their own dedicated modules. 
+
+### Relevant articles:
 
 - [Dijkstra Shortest Path Algorithm in Java](https://www.baeldung.com/java-dijkstra)
 - [Introduction to Cobertura](https://www.baeldung.com/cobertura)
@@ -8,3 +13,4 @@
 - [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)
+- More articles: [[<-- prev]](/../algorithms-miscellaneous-1) [[next -->]](/../algorithms-miscellaneous-3)

algorithms-miscellaneous-4/README.md

@@ -1,4 +1,9 @@
-## Relevant articles:
+## Algorithms - Miscellaneous
+
+This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](/../algorithms-sorting) and
+[genetic algorithms](/../algorithms-genetic), have their own dedicated modules. 
+
+### 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)
@@ -6,4 +11,5 @@
 - [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)
+- [Permutations of an Array in Java](https://www.baeldung.com/java-array-permutations)
+- More articles: [[<-- prev]](/../algorithms-miscellaneous-3) [[next -->]](/../algorithms-miscellaneous-5)

algorithms-miscellaneous-5/README.md

@@ -1,5 +1,11 @@
-## Relevant articles:
+## Algorithms - Miscellaneous
+
+This module contains articles about algorithms. Some classes of algorithms, e.g., [sorting](/../algorithms-sorting) and
+[genetic algorithms](/../algorithms-genetic), have their own dedicated modules. 
+
+### Relevant articles:
 
 - [Converting Between Byte Arrays and Hexadecimal Strings in Java](https://www.baeldung.com/java-byte-arrays-hex-strings)
 - [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)
+- [Find If Two Numbers Are Relatively Prime in Java](https://www.baeldung.com/java-two-relatively-prime-numbers)
+- More articles: [[<-- prev]](/../algorithms-miscellaneous-4)

algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/knapsack/Knapsack.java

@@ -0,0 +1,36 @@
+package com.baeldung.algorithms.knapsack;
+
+public class Knapsack {
+
+    public int knapsackRec(int[] w, int[] v, int n, int W) {
+        if (n <= 0) {
+            return 0;
+        } else if (w[n - 1] > W) {
+            return knapsackRec(w, v, n - 1, W);
+        } else {
+            return Math.max(knapsackRec(w, v, n - 1, W), v[n - 1] + knapsackRec(w, v, n - 1, W - w[n - 1]));
+        }
+    }
+
+    public int knapsackDP(int[] w, int[] v, int n, int W) {
+        if (n <= 0 || W <= 0) {
+            return 0;
+        }
+
+        int[][] m = new int[n + 1][W + 1];
+        for (int j = 0; j <= W; j++) {
+            m[0][j] = 0;
+        }
+
+        for (int i = 1; i <= n; i++) {
+            for (int j = 1; j <= W; j++) {
+                if (w[i - 1] > j) {
+                    m[i][j] = m[i - 1][j];
+                } else {
+                    m[i][j] = Math.max(m[i - 1][j], m[i - 1][j - w[i - 1]] + v[i - 1]);
+                }
+            }
+        }
+        return m[n][W];
+    }
+}

algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/knapsack/KnapsackUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.algorithms.knapsack;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class KnapsackUnitTest {
+
+    @Test
+    public void givenWeightsandValues_whenCalculateMax_thenOutputCorrectResult() {
+        final int[] w = new int[] { 23, 26, 20, 18, 32, 27, 29, 26, 30, 27 };
+        final int[] v = new int[] { 505, 352, 458, 220, 354, 414, 498, 545, 473, 543 };
+        final int n = 10;
+        final int W = 67;
+        final Knapsack knapsack = new Knapsack();
+
+        assertEquals(1270, knapsack.knapsackRec(w, v, n, W));
+        assertEquals(1270, knapsack.knapsackDP(w, v, n, W));
+    }
+
+    @Test
+    public void givenZeroItems_whenCalculateMax_thenOutputZero() {
+        final int[] w = new int[] {};
+        final int[] v = new int[] {};
+        final int n = 0;
+        final int W = 67;
+        final Knapsack knapsack = new Knapsack();
+
+        assertEquals(0, knapsack.knapsackRec(w, v, n, W));
+        assertEquals(0, knapsack.knapsackDP(w, v, n, W));
+    }
+
+    @Test
+    public void givenZeroWeightLimit_whenCalculateMax_thenOutputZero() {
+        final int[] w = new int[] { 23, 26, 20, 18, 32, 27, 29, 26, 30, 27 };
+        final int[] v = new int[] { 505, 352, 458, 220, 354, 414, 498, 545, 473, 543 };
+        final int n = 10;
+        final int W = 0;
+        final Knapsack knapsack = new Knapsack();
+
+        assertEquals(0, knapsack.knapsackRec(w, v, n, W));
+        assertEquals(0, knapsack.knapsackDP(w, v, n, W));
+    }
+}

algorithms-sorting/README.md

@@ -16,3 +16,4 @@ This module contains articles about sorting algorithms.
 - [Selection Sort in Java](https://www.baeldung.com/java-selection-sort)
 - [Sorting Strings by Contained Numbers in Java](https://www.baeldung.com/java-sort-strings-contained-numbers)
 - [Radix Sort in Java](https://www.baeldung.com/java-radix-sort)
+- [Sorting a String Alphabetically in Java](https://www.baeldung.com/java-sort-string-alphabetically)

algorithms-sorting/pom.xml

@@ -28,6 +28,12 @@
             <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit-jupiter-api.version}</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
@@ -52,6 +58,7 @@
         <commons-math3.version>3.6.1</commons-math3.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>
+        <junit-jupiter-api.version>5.3.1</junit-jupiter-api.version>
     </properties>
 
 </project>

algorithms-sorting/src/main/java/com/baeldung/algorithms/stringsort/AnagramValidator.java

@@ -1,4 +1,4 @@
-package com.baeldung.string.sorting;
+package com.baeldung.algorithms.stringsort;
 
 import java.util.Arrays;
 

algorithms-sorting/src/test/java/com/baeldung/algorithms/stringsort/AnagramValidatorUnitTest.java

@@ -1,12 +1,10 @@
-package com.baeldung.string.sorting;
+package com.baeldung.algorithms.stringsort;
 
 
-import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-
 import org.junit.jupiter.api.Test;
 
-import com.baeldung.string.sorting.AnagramValidator;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class AnagramValidatorUnitTest {
     

algorithms-sorting/src/test/java/com/baeldung/algorithms/stringsort/SortStringUnitTest.java

@@ -1,9 +1,9 @@
-package com.baeldung.string.sorting;
-
-import java.util.Arrays;
+package com.baeldung.algorithms.stringsort;
 
 import org.junit.jupiter.api.Test;
 
+import java.util.Arrays;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 class SortStringUnitTest {

core-java-modules/core-java-8/src/main/java/com/baeldung/java_8_features/groupingby/Tuple.java

@@ -1,12 +1,12 @@
 package com.baeldung.java_8_features.groupingby;
 
-public class Tuple {
+import java.util.Objects;
+
+public class Tuple {
+    private final BlogPostType type;
+    private final String author;
 
-    private BlogPostType type;
-    private String author;
-    
     public Tuple(BlogPostType type, String author) {
-        super();
         this.type = type;
         this.author = author;
     }
@@ -15,20 +15,27 @@ public class Tuple {
         return type;
     }
 
-    public void setType(BlogPostType type) {
-        this.type = type;
-    }
-
     public String getAuthor() {
         return author;
     }
 
-    public void setAuthor(String author) {
-        this.author = author;
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Tuple tuple = (Tuple) o;
+        return type == tuple.type && author.equals(tuple.author);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(type, author);
     }
 
     @Override
     public String toString() {
-        return "Tuple [type=" + type + ", author=" + author + ", getType()=" + getType() + ", getAuthor()=" + getAuthor() + ", getClass()=" + getClass() + ", hashCode()=" + hashCode() + ", toString()=" + super.toString() + "]";
+        return "Tuple{" + "type=" + type + ", author='" + author + '\'' + '}';
     }
 }

core-java-modules/core-java-8/src/test/java/com/baeldung/java_8_features/groupingby/Java8GroupingByCollectorUnitTest.java

@@ -1,15 +1,32 @@
 package com.baeldung.java_8_features.groupingby;
 
-import com.baeldung.java_8_features.groupingby.BlogPost;
-import com.baeldung.java_8_features.groupingby.BlogPostType;
-import org.junit.Test;
+import static java.util.Comparator.comparingInt;
+import static java.util.stream.Collectors.averagingInt;
+import static java.util.stream.Collectors.counting;
+import static java.util.stream.Collectors.groupingBy;
+import static java.util.stream.Collectors.groupingByConcurrent;
+import static java.util.stream.Collectors.joining;
+import static java.util.stream.Collectors.mapping;
+import static java.util.stream.Collectors.maxBy;
+import static java.util.stream.Collectors.summarizingInt;
+import static java.util.stream.Collectors.summingInt;
+import static java.util.stream.Collectors.toList;
+import static java.util.stream.Collectors.toSet;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 
-import java.util.*;
+import java.util.Arrays;
+import java.util.EnumMap;
+import java.util.IntSummaryStatistics;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
 
-import static java.util.Comparator.comparingInt;
-import static java.util.stream.Collectors.*;
-import static org.junit.Assert.*;
+import org.junit.Test;
 
 public class Java8GroupingByCollectorUnitTest {
 
@@ -180,4 +197,19 @@ public class Java8GroupingByCollectorUnitTest {
         assertEquals(15, newsLikeStatistics.getMin());
     }
 
+    @Test
+    public void givenAListOfPosts_whenGroupedByComplexMapKeyType_thenGetAMapBetweenTupleAndList() {
+        Map<Tuple, List<BlogPost>> postsPerTypeAndAuthor = posts.stream()
+            .collect(groupingBy(post -> new Tuple(post.getType(), post.getAuthor())));
+
+        List<BlogPost> result = postsPerTypeAndAuthor.get(new Tuple(BlogPostType.GUIDE, "Author 1"));
+
+        assertThat(result.size()).isEqualTo(1);
+
+        BlogPost blogPost = result.get(0);
+
+        assertThat(blogPost.getTitle()).isEqualTo("Programming guide");
+        assertThat(blogPost.getType()).isEqualTo(BlogPostType.GUIDE);
+        assertThat(blogPost.getAuthor()).isEqualTo("Author 1");
+    }
 }

core-java-modules/core-java-arrays-2/src/main/java/com/baeldung/array/operations/ArrayOperations.java

@@ -192,15 +192,48 @@ public class ArrayOperations {
         return array[new Random().nextInt(array.length)];
     }
 
-    public static Integer[] intersectionSimple(final Integer[] a, final Integer[] b){
-        return Stream.of(a).filter(Arrays.asList(b)::contains).toArray(Integer[]::new);
+    public static Integer[] intersectionSimple(final Integer[] a, final Integer[] b) {
+        return Stream.of(a)
+            .filter(Arrays.asList(b)::contains)
+            .toArray(Integer[]::new);
     }
 
-    public static Integer[] intersectionSet(final Integer[] a, final Integer[] b){
-        return Stream.of(a).filter(Arrays.asList(b)::contains).distinct().toArray(Integer[]::new);
+    public static Integer[] intersectionSet(final Integer[] a, final Integer[] b) {
+        return Stream.of(a)
+            .filter(Arrays.asList(b)::contains)
+            .distinct()
+            .toArray(Integer[]::new);
     }
 
-    public static Integer[] intersectionMultiSet(final Integer[] a, final Integer[] b){
-        return Stream.of(a).filter(new LinkedList<>(Arrays.asList(b))::remove).toArray(Integer[]::new);
+    public static Integer[] intersectionMultiSet(final Integer[] a, final Integer[] b) {
+        return Stream.of(a)
+            .filter(new LinkedList<>(Arrays.asList(b))::remove)
+            .toArray(Integer[]::new);
+    }
+
+    public static Integer[] addElementUsingPureJava(Integer[] srcArray, int elementToAdd) {
+        Integer[] destArray = new Integer[srcArray.length + 1];
+
+        for (int i = 0; i < srcArray.length; i++) {
+            destArray[i] = srcArray[i];
+        }
+
+        destArray[destArray.length - 1] = elementToAdd;
+        return destArray;
+    }
+
+    public static int[] insertAnElementAtAGivenIndex(final int[] srcArray, int index, int newElement) {
+        int[] destArray = new int[srcArray.length + 1];
+        int j = 0;
+        for (int i = 0; i < destArray.length - 1; i++) {
+
+            if (i == index) {
+                destArray[i] = newElement;
+            } else {
+                destArray[i] = srcArray[j];
+                j++;
+            }
+        }
+        return destArray;
     }
 }

core-java-modules/core-java-arrays-2/src/main/java/com/baeldung/arraylist/operations/ArrayListOperations.java

@@ -0,0 +1,23 @@
+package com.baeldung.arraylist.operations;
+
+import java.util.ArrayList;
+
+public class ArrayListOperations {
+
+    public static Integer getAnIntegerElement(ArrayList<Integer> anArrayList, int index) {
+        return anArrayList.get(index);
+    }
+
+    public static void modifyAnIntegerElement(ArrayList<Integer> anArrayList, int index, Integer newElement) {
+        anArrayList.set(index, newElement);
+    }
+
+    public static void appendAnIntegerElement(ArrayList<Integer> anArrayList, Integer newElement) {
+        anArrayList.add(newElement);
+    }
+
+    public static void insertAnIntegerElementAtIndex(ArrayList<Integer> anArrayList, int index, Integer newElement) {
+        anArrayList.add(index, newElement);
+    }
+
+}

core-java-modules/core-java-arrays-2/src/test/java/com/baeldung/array/operations/ArrayOperationsUnitTest.java

@@ -1,12 +1,11 @@
 package com.baeldung.array.operations;
 
+import java.util.Arrays;
 import org.assertj.core.api.Condition;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-
-import java.util.Arrays;
-
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertArrayEquals;
 
 public class ArrayOperationsUnitTest {
 
@@ -262,8 +261,7 @@ public class ArrayOperationsUnitTest {
 
     @Test
     public void whenMapIntArrayToString_thenReturnArray() {
-        String[] expectedArray = new String[] { "Value: 3", "Value: 5", "Value: 2", "Value: 5", "Value: 14",
-                "Value: 4" };
+        String[] expectedArray = new String[] { "Value: 3", "Value: 5", "Value: 2", "Value: 5", "Value: 14", "Value: 4" };
         String[] output = ArrayOperations.mapIntArrayToString(defaultIntArray);
 
         assertThat(output).containsExactly(expectedArray);
@@ -313,13 +311,10 @@ public class ArrayOperationsUnitTest {
         int[] output5 = ArrayOperations.shuffleIntArray(defaultIntArray);
         int[] output6 = ArrayOperations.shuffleIntArray(defaultIntArray);
 
-        Condition<int[]> atLeastOneArraysIsNotEqual = new Condition<int[]>(
-            "at least one output should be different (order-wise)") {
+        Condition<int[]> atLeastOneArraysIsNotEqual = new Condition<int[]>("at least one output should be different (order-wise)") {
             @Override
             public boolean matches(int[] value) {
-                return !Arrays.equals(value, output) || !Arrays.equals(value, output2) || !Arrays.equals(value, output3)
-                    || !Arrays.equals(value, output4) || !Arrays.equals(value, output5)
-                    || !Arrays.equals(value, output6);
+                return !Arrays.equals(value, output) || !Arrays.equals(value, output2) || !Arrays.equals(value, output3) || !Arrays.equals(value, output4) || !Arrays.equals(value, output5) || !Arrays.equals(value, output6);
             }
         };
 
@@ -335,13 +330,10 @@ public class ArrayOperationsUnitTest {
         Integer[] output5 = ArrayOperations.shuffleObjectArray(defaultObjectArray);
         Integer[] output6 = ArrayOperations.shuffleObjectArray(defaultObjectArray);
 
-        Condition<Integer[]> atLeastOneArraysIsNotEqual = new Condition<Integer[]>(
-            "at least one output should be different (order-wise)") {
+        Condition<Integer[]> atLeastOneArraysIsNotEqual = new Condition<Integer[]>("at least one output should be different (order-wise)") {
             @Override
             public boolean matches(Integer[] value) {
-                return !Arrays.equals(value, output) || !Arrays.equals(value, output2) || !Arrays.equals(value, output3)
-                    || !Arrays.equals(value, output4) || !Arrays.equals(value, output5)
-                    || !Arrays.equals(value, output6);
+                return !Arrays.equals(value, output) || !Arrays.equals(value, output2) || !Arrays.equals(value, output3) || !Arrays.equals(value, output4) || !Arrays.equals(value, output5) || !Arrays.equals(value, output6);
             }
         };
 
@@ -362,4 +354,27 @@ public class ArrayOperationsUnitTest {
 
         assertThat(defaultObjectArray).contains(output);
     }
+
+    @Test
+    public void givenSourceArrayAndElement_whenAddElementUsingPureJavaIsInvoked_thenNewElementMustBeAdded() {
+        Integer[] sourceArray = { 1, 2, 3, 4 };
+        int elementToAdd = 5;
+
+        Integer[] destArray = ArrayOperations.addElementUsingPureJava(sourceArray, elementToAdd);
+
+        Integer[] expectedArray = { 1, 2, 3, 4, 5 };
+        assertArrayEquals(expectedArray, destArray);
+    }
+
+    @Test
+    public void whenInsertAnElementAtAGivenIndexCalled_thenShiftTheFollowingElementsAndInsertTheElementInArray() {
+        int[] expectedArray = { 1, 4, 2, 3, 0 };
+        int[] anArray = new int[4];
+        anArray[0] = 1;
+        anArray[1] = 2;
+        anArray[2] = 3;
+        int[] outputArray = ArrayOperations.insertAnElementAtAGivenIndex(anArray, 1, 4);
+
+        assertThat(outputArray).containsExactly(expectedArray);
+    }
 }

core-java-modules/core-java-arrays-2/src/test/java/com/baeldung/arraylist/operations/ArrayListOperationsUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.arraylist.operations;
+
+import java.util.ArrayList;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ArrayListOperationsUnitTest {
+
+    private ArrayList<Integer> anArrayList;
+
+    @BeforeEach
+    public void setupDefaults() {
+        anArrayList = new ArrayList<>();
+        anArrayList.add(2);
+        anArrayList.add(3);
+        anArrayList.add(4);
+    }
+
+    @Test
+    public void whenGetAnIntegerElementCalled_thenReturnTheIntegerElement() {
+        Integer output = ArrayListOperations.getAnIntegerElement(anArrayList, 1);
+
+        assertThat(output).isEqualTo(3);
+    }
+
+    @Test
+    public void whenModifyAnIntegerElementCalled_thenModifyTheIntegerElement() {
+        ArrayListOperations.modifyAnIntegerElement(anArrayList, 2, 5);
+        Integer output = ArrayListOperations.getAnIntegerElement(anArrayList, 2);
+
+        assertThat(output).isEqualTo(5);
+    }
+
+    @Test
+    public void whenAppendAnIntegerElementCalled_thenTheIntegerElementIsAppendedToArrayList() {
+        ArrayListOperations.appendAnIntegerElement(anArrayList, 6);
+        Integer output = ArrayListOperations.getAnIntegerElement(anArrayList, anArrayList.size() - 1);
+
+        assertThat(output).isEqualTo(6);
+    }
+
+    @Test
+    public void whenInsertAnIntegerAtIndexCalled_thenTheIntegerElementIsInseredToArrayList() {
+        ArrayListOperations.insertAnIntegerElementAtIndex(anArrayList, 1, 10);
+        Integer output = ArrayListOperations.getAnIntegerElement(anArrayList, 1);
+
+        assertThat(output).isEqualTo(10);
+    }
+}

core-java-modules/core-java-collections-list-3/src/main/java/com/baeldung/list/DuplicatesCounter.java

@@ -0,0 +1,42 @@
+package com.baeldung.list;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ * Demo different approaches to get count of duplicated elements in an
+ * arrayList
+ */
+public class DuplicatesCounter {
+
+    public static <T> Map<T, Long> countByClassicalLoop(List<T> inputList) {
+        Map<T, Long> resultMap = new HashMap<>();
+        for (T element : inputList) {
+            if (resultMap.containsKey(element)) {
+                resultMap.put(element, resultMap.get(element) + 1L);
+            } else {
+                resultMap.put(element, 1L);
+            }
+        }
+        return resultMap;
+    }
+
+    public static <T> Map<T, Long> countByClassicalLoopWithMapCompute(List<T> inputList) {
+        Map<T, Long> resultMap = new HashMap<>();
+        for (T element : inputList) {
+            resultMap.compute(element, (k, v) -> v == null ? 1 : v + 1);
+        }
+        return resultMap;
+    }
+
+    public static <T> Map<T, Long> countByStreamToMap(List<T> inputList) {
+        return inputList.stream().collect(Collectors.toMap(Function.identity(), v -> 1L, Long::sum));
+    }
+
+    public static <T> Map<T, Long> countByStreamGroupBy(List<T> inputList) {
+        return inputList.stream().collect(Collectors.groupingBy(k -> k, Collectors.counting()));
+    }
+}

core-java-modules/core-java-collections-list-3/src/test/java/com/baeldung/list/DuplicatesCounterUnitTest.java

@@ -0,0 +1,55 @@
+package com.baeldung.list;
+
+import org.assertj.core.util.Lists;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.data.MapEntry.entry;
+
+class DuplicatesCounterUnitTest {
+
+
+    private static List<String> INPUT_LIST = Lists.list(
+        "expect1",
+        "expect2", "expect2",
+        "expect3", "expect3", "expect3",
+        "expect4", "expect4", "expect4", "expect4");
+
+    @Test
+    void givenInput_whenCountByClassicalLoop_thenGetResultMap() {
+        Map<String, Long> result = DuplicatesCounter.countByClassicalLoop(INPUT_LIST);
+        verifyResult(result);
+    }
+
+
+    @Test
+    void givenInput_whenCountByClassicalLoopWithMapCompute_thenGetResultMap() {
+        Map<String, Long> result = DuplicatesCounter.countByClassicalLoopWithMapCompute(INPUT_LIST);
+        verifyResult(result);
+    }
+
+    @Test
+    void givenInput_whenCountByStreamToMap_thenGetResultMap() {
+        Map<String, Long> result = DuplicatesCounter.countByStreamToMap(INPUT_LIST);
+        verifyResult(result);
+    }
+
+    @Test
+    void givenInput_whenCountByStreamGroupBy_thenGetResultMap() {
+        Map<String, Long> result = DuplicatesCounter.countByStreamGroupBy(INPUT_LIST);
+        verifyResult(result);
+    }
+
+    private void verifyResult(Map<String, Long> resultMap) {
+        assertThat(resultMap)
+            .isNotEmpty().hasSize(4)
+            .containsExactly(
+                entry("expect1", 1L),
+                entry("expect2", 2L),
+                entry("expect3", 3L),
+                entry("expect4", 4L));
+    }
+}

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

@@ -0,0 +1,9 @@
+## Java Date/time conversion Cookbooks and Examples
+
+This module contains articles about converting between Java date and time objects.
+
+### Relevant Articles: 
+- [Converting Between LocalDate and XMLGregorianCalendar](https://www.baeldung.com/java-localdate-to-xmlgregoriancalendar)
+- [Convert Time to Milliseconds in Java](https://www.baeldung.com/java-time-milliseconds)
+- [Convert Date to LocalDate or LocalDateTime and Back](http://www.baeldung.com/java-date-to-localdate-and-localdatetime)
+- [Convert Between java.time.Instant and java.sql.Timestamp](https://www.baeldung.com/java-time-instant-to-java-sql-timestamp)

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

@@ -0,0 +1,70 @@
+<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-datetime-conversion</artifactId>
+    <version>${project.parent.version}</version>
+    <name>core-java-datetime-conversion</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-datetime-conversion</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <joda-time.version>2.10</joda-time.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+		<maven.compiler.source>1.9</maven.compiler.source>
+        <maven.compiler.target>1.9</maven.compiler.target>
+    </properties>
+</project>

core-java-modules/core-java-datetime-conversion/src/test/java/com/baeldung/datetime/ConvertInstantToTimestampUnitTest.java

@@ -1,15 +1,14 @@
 package com.baeldung.datetime;
 
-import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
 
 import java.sql.Timestamp;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.time.Instant;
-import java.time.ZoneId;
 import java.util.TimeZone;
 
-import org.junit.Test;
+import static org.assertj.core.api.Assertions.assertThat;
 
 public class ConvertInstantToTimestampUnitTest {
 

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

@@ -0,0 +1,13 @@
+## Java Dates Parsing and Formatting Cookbooks and Examples
+
+This module contains articles about parsing and formatting Java date and time objects.
+
+### Relevant Articles: 
+- [Check If a String Is a Valid Date in Java](https://www.baeldung.com/java-string-valid-date)
+- [RegEx for matching Date Pattern in Java](http://www.baeldung.com/java-date-regular-expressions)
+- [Guide to DateTimeFormatter](https://www.baeldung.com/java-datetimeformatter)
+- [Format ZonedDateTime to String](https://www.baeldung.com/java-format-zoned-datetime-string)
+- [A Guide to SimpleDateFormat](https://www.baeldung.com/java-simple-date-format)
+- [Display All Time Zones With GMT And UTC in Java](http://www.baeldung.com/java-time-zones)
+- [Convert between String and Timestamp](https://www.baeldung.com/java-string-to-timestamp)
+- [Convert String to Date in Java](http://www.baeldung.com/java-string-to-date)

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

@@ -1,39 +1,35 @@
 <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>java-dates-2</artifactId>
-    <version>0.1.0-SNAPSHOT</version>
+    <artifactId>core-java-datetime-string</artifactId>
+    <version>${project.parent.version}</version>
+    <name>core-java-datetime-string</name>
     <packaging>jar</packaging>
-    <name>java-dates-2</name>
 
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-java</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../../parent-java</relativePath>
     </parent>
 
     <dependencies>
-        <dependency>
-            <groupId>joda-time</groupId>
-            <artifactId>joda-time</artifactId>
-            <version>${joda-time.version}</version>
-        </dependency>
-
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
             <version>${commons-lang3.version}</version>
         </dependency>
-
         <!-- https://mvnrepository.com/artifact/commons-validator/commons-validator -->
         <dependency>
             <groupId>commons-validator</groupId>
             <artifactId>commons-validator</artifactId>
             <version>${commons-validator.version}</version>
         </dependency>
-
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
         <!-- test scoped -->
         <dependency>
             <groupId>org.assertj</groupId>
@@ -41,10 +37,21 @@
             <version>${assertj.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.darwinsys</groupId>
+            <artifactId>hirondelle-date4j</artifactId>
+            <version>RELEASE</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
-        <finalName>java-dates-2</finalName>
+        <finalName>core-java-datetime-string</finalName>
         <resources>
             <resource>
                 <directory>src/main/resources</directory>
@@ -66,12 +73,11 @@
     </build>
 
     <properties>
+        <commons-validator.version>1.6</commons-validator.version>
+        <joda-time.version>2.10</joda-time.version>
         <!-- testing -->
         <assertj.version>3.6.1</assertj.version>
-        <joda-time.version>2.10</joda-time.version>
-        <commons-lang3.version>3.9</commons-lang3.version>
-        <commons-validator.version>1.6</commons-validator.version>
-        <maven.compiler.source>1.9</maven.compiler.source>
+		<maven.compiler.source>1.9</maven.compiler.source>
         <maven.compiler.target>1.9</maven.compiler.target>
     </properties>
 </project>

core-java-modules/core-java-datetime-string/src/main/java/com/baeldung/zonedatetime/OffsetDateTimeExample.java

@@ -1,4 +1,4 @@
-package com.baeldung.zoneddatetime;
+package com.baeldung.zonedatetime;
 
 import java.time.OffsetDateTime;
 import java.time.ZoneOffset;

core-java-modules/core-java-datetime-string/src/main/java/com/baeldung/zonedatetime/OffsetTimeExample.java

@@ -1,4 +1,4 @@
-package com.baeldung.zoneddatetime;
+package com.baeldung.zonedatetime;
 
 import java.time.OffsetTime;
 import java.time.ZoneOffset;

core-java-modules/core-java-datetime-string/src/main/java/com/baeldung/zonedatetime/ZoneDateTimeExample.java

@@ -1,4 +1,4 @@
-package com.baeldung.zoneddatetime;
+package com.baeldung.zonedatetime;
 
 import java.time.ZoneId;
 import java.time.ZonedDateTime;

core-java-modules/core-java-datetime-string/src/test/java/com/baeldung/zonedatetime/OffsetDateTimeExampleUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.zoneddatetime;
+package com.baeldung.zonedatetime;
 
 import static org.junit.Assert.assertTrue;
 

core-java-modules/core-java-datetime-string/src/test/java/com/baeldung/zonedatetime/OffsetTimeExampleUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.zoneddatetime;
+package com.baeldung.zonedatetime;
 
 import static org.junit.Assert.assertTrue;
 

core-java-modules/core-java-datetime-string/src/test/java/com/baeldung/zonedatetime/ZoneDateTimeExampleUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.zoneddatetime;
+package com.baeldung.zonedatetime;
 
 import static org.junit.Assert.assertTrue;
 

core-java-modules/core-java-datetime-string/src/test/java/com/baeldung/zonedatetime/ZonedDateTimeUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.zoneddatetime;
+package com.baeldung.zonedatetime;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 

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

@@ -1,7 +0,0 @@
-=========
-
-## Core Java 8 Cookbooks and Examples
-
-### Relevant Articles: 
-- [Set the Time Zone of a Date in Java](https://www.baeldung.com/java-set-date-time-zone)
-- [Overriding System Time for Testing in Java](https://www.baeldung.com/java-override-system-time)

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

@@ -1,82 +0,0 @@
-<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-datetime</artifactId>
-    <version>0.1.0-SNAPSHOT</version>
-    <name>core-java-datetime</name>
-    <packaging>jar</packaging>
-
-    <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
-        <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../../parent-java</relativePath>
-    </parent>
-
-    <dependencies>
-        <!-- test scoped -->
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>joda-time</groupId>
-            <artifactId>joda-time</artifactId>
-            <version>${joda.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.powermock</groupId>
-            <artifactId>powermock-module-junit4</artifactId>
-            <version>${powermock.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.powermock</groupId>
-            <artifactId>powermock-api-mockito2</artifactId>
-            <version>${powermock.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jmockit</groupId>
-            <artifactId>jmockit</artifactId>
-            <version>${jmockit.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <build>
-        <finalName>core-java-datetime</finalName>
-        <resources>
-            <resource>
-                <directory>src/main/resources</directory>
-                <filtering>true</filtering>
-            </resource>
-        </resources>
-
-        <plugins>
-            <plugin>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <version>${maven-surefire-plugin.version}</version>
-                <configuration>
-                    <argLine>
-                        -javaagent:${settings.localRepository}/org/jmockit/jmockit/${jmockit.version}/jmockit-${jmockit.version}.jar
-                    </argLine>
-                    <disableXmlReport>true</disableXmlReport>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
-
-    <properties>
-        <!-- util -->
-        <joda.version>2.10</joda.version>
-        <!-- testing -->
-        <assertj.version>3.6.1</assertj.version>
-        <powermock.version>2.0.0-RC.4</powermock.version>
-        <jmockit.version>1.44</jmockit.version>
-        <!-- plugins -->
-        <maven-surefire-plugin.version>2.22.1</maven-surefire-plugin.version>
-    </properties>
-</project>

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

@@ -3,7 +3,6 @@
          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.consumermodule</groupId>
     <artifactId>consumermodule</artifactId>
     <version>1.0</version>

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

@@ -3,16 +3,16 @@
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.servicemodule</groupId>
+    <artifactId>servicemodule</artifactId>
+    <version>1.0</version>
+
     <parent>
         <artifactId>>com.baeldung.decoupling-pattern2</artifactId>
         <groupId>decoupling-pattern2</groupId>
         <version>1.0-SNAPSHOT</version>
     </parent>
 
-    <groupId>com.baeldung.servicemodule</groupId>
-    <artifactId>servicemodule</artifactId>
-    <version>1.0</version>
-
     <build>
         <plugins>
             <plugin>

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

@@ -28,12 +28,6 @@
             <scope>test</scope>
         </dependency>
 	</dependencies>
-
-    <properties>
-        <!-- testing -->
-        <assertj-core.version>3.10.0</assertj-core.version>
-        <equalsverifier.version>3.0.3</equalsverifier.version>
-    </properties>
     
     <build>
         <finalName>core-java-lang-oop-2</finalName>
@@ -45,4 +39,10 @@
         </resources>
     </build>
 
+    <properties>
+        <!-- testing -->
+        <assertj-core.version>3.10.0</assertj-core.version>
+        <equalsverifier.version>3.0.3</equalsverifier.version>
+    </properties>
+
 </project>

core-java-modules/core-java-lang-syntax-2/src/main/java/com/baeldung/core/modifiers/FirstClass.java

@@ -0,0 +1,18 @@
+package com.baeldung.core.modifiers;
+
+public class FirstClass {
+
+    protected String name;
+    
+    protected FirstClass(String name) {
+        this.name = name;
+    }
+
+    protected String getName() {
+        return name;
+    }
+
+    protected static class InnerClass {
+        public InnerClass() {}
+    }
+}

core-java-modules/core-java-lang-syntax-2/src/main/java/com/baeldung/core/modifiers/GenericClass.java

@@ -0,0 +1,15 @@
+package com.baeldung.core.modifiers;
+
+public class GenericClass {
+
+    public static void main(String[] args) {
+        // accessing protected constructor
+        FirstClass first = new FirstClass("random name");
+        // using protected method
+        System.out.println("FirstClass name is " + first.getName());
+        // accessing a protected field
+        first.name = "new name";
+        // instantiating protected inner class
+        FirstClass.InnerClass innerClass = new FirstClass.InnerClass();
+    }
+}

core-java-modules/core-java-lang-syntax-2/src/main/java/com/baeldung/core/modifiers/otherpackage/SecondClass.java

@@ -0,0 +1,18 @@
+package com.baeldung.core.modifiers.otherpackage;
+
+import com.baeldung.core.modifiers.FirstClass;
+
+public class SecondClass extends FirstClass {
+    
+    public SecondClass(String name) {
+        // accessing protected constructor
+        super(name);
+        // using protected method
+        System.out.println("SecondClass name is " + this.getName());
+        // accessing a protected field
+        this.name = "new name";
+        // instantiating protected inner class -> add public constructor to InnerClass
+        FirstClass.InnerClass innerClass = new FirstClass.InnerClass();
+    }
+      
+}

core-java-modules/core-java-lang-syntax-2/src/main/java/com/baeldung/core/modifiers/otherpackage/SecondGenericClass.java

@@ -0,0 +1,20 @@
+package com.baeldung.core.modifiers.otherpackage;
+
+import com.baeldung.core.modifiers.FirstClass;
+//import com.baeldung.core.modifiers.FirstClass.InnerClass;
+
+public class SecondGenericClass {
+
+    // uncomment the following lines to see the errors
+    public static void main(String[] args) {
+        // accessing protected constructor
+        // FirstClass first = new FirstClass("random name");
+        // using protected method
+        // System.out.println("FirstClass name is " + first.getName());
+        // accessing a protected field
+        // first.name = "new name";
+        // instantiating protected inner class
+        // FirstClass.InnerClass innerClass = new FirstClass.InnerClass();
+    }
+
+}

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

@@ -54,7 +54,7 @@
         </resources>
 
         <plugins>
-         <plugin>
+            <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>${maven-compiler-plugin.version}</version>

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

@@ -0,0 +1,12 @@
+## Java String APIs
+
+This module contains articles about string APIs.
+
+### Relevant Articles:
+- [Java 8 StringJoiner](https://www.baeldung.com/java-string-joiner)
+- [Quick Guide to the Java StringTokenizer](https://www.baeldung.com/java-stringtokenizer)
+- [Guide to java.util.Formatter](https://www.baeldung.com/java-string-formatter)
+- [Guide to StreamTokenizer](https://www.baeldung.com/java-streamtokenizer)
+- [CharSequence vs. String in Java](https://www.baeldung.com/java-char-sequence-string)
+- [StringBuilder and StringBuffer in Java](https://www.baeldung.com/java-string-builder-string-buffer)
+- [Generate a Secure Random Password in Java](https://www.baeldung.com/java-generate-secure-password)

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

@@ -0,0 +1,55 @@
+<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-apis</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>core-java-string-apis</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <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>
+        <!-- Added for password generation -->
+        <dependency>
+            <groupId>org.passay</groupId>
+            <artifactId>passay</artifactId>
+            <version>${passay.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-text</artifactId>
+            <version>${commons-text.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-string-apis</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <passay.version>1.3.1</passay.version>
+        <commons-text.version>1.4</commons-text.version>
+    </properties>
+
+</project>

core-java-modules/core-java-string-apis/src/main/java/com/baeldung/password/RandomPasswordGenerator.java

@@ -1,4 +1,11 @@
-package com.baeldung.string.password;
+package com.baeldung.password;
+
+import org.apache.commons.lang3.RandomStringUtils;
+import org.apache.commons.text.RandomStringGenerator;
+import org.passay.CharacterRule;
+import org.passay.EnglishCharacterData;
+import org.passay.CharacterData;
+import org.passay.PasswordGenerator;
 
 import java.security.SecureRandom;
 import java.util.Collections;
@@ -8,13 +15,6 @@ import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
-import org.apache.commons.lang3.RandomStringUtils;
-import org.apache.commons.text.RandomStringGenerator;
-import org.passay.CharacterData;
-import org.passay.CharacterRule;
-import org.passay.EnglishCharacterData;
-import org.passay.PasswordGenerator;
-
 public class RandomPasswordGenerator {
 
     /**

core-java-modules/core-java-string-apis/src/main/java/com/baeldung/streamtokenizer/StreamTokenizerDemo.java

@@ -1,4 +1,4 @@
-package com.baeldung.string.streamtokenizer;
+package com.baeldung.streamtokenizer;
 
 import java.io.*;
 import java.util.ArrayList;

core-java-modules/core-java-string-apis/src/main/java/com/baeldung/stringbuilderstringbuffer/StringBuilderStringBuffer.java

@@ -1,4 +1,4 @@
-package com.baeldung.string;
+package com.baeldung.stringbuilderstringbuffer;
 
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.Scope;
@@ -8,12 +8,12 @@ import org.openjdk.jmh.runner.RunnerException;
 import org.openjdk.jmh.runner.options.Options;
 import org.openjdk.jmh.runner.options.OptionsBuilder;
 
-public class StringBufferStringBuilder {
+public class StringBuilderStringBuffer {
 
     public static void main(String[] args) throws RunnerException {
 
         Options opt = new OptionsBuilder()
-            .include(StringBufferStringBuilder.class.getSimpleName())
+            .include(StringBuilderStringBuffer.class.getSimpleName())
             .build();
 
         new Runner(opt).run();

core-java-modules/core-java-string-apis/src/test/java/com/baeldung/charsequence/CharSequenceVsStringUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.string;
+package com.baeldung.charsequence;
 
 import org.junit.Test;
 

core-java-modules/core-java-string-apis/src/test/java/com/baeldung/formatter/StringFormatterExampleUnitTest.java

@@ -1,12 +1,12 @@
-package com.baeldung.string.formatter;
+package com.baeldung.formatter;
+
+import org.junit.Test;
 
 import java.util.Calendar;
 import java.util.Formatter;
 import java.util.GregorianCalendar;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-import org.junit.Test;
+
+import static org.junit.Assert.*;
 
 public class StringFormatterExampleUnitTest {
 

core-java-modules/core-java-string-apis/src/test/java/com/baeldung/password/StringPasswordUnitTest.java

@@ -1,9 +1,9 @@
-package com.baeldung.string.password;
-
-import static org.junit.Assert.assertTrue;
+package com.baeldung.password;
 
 import org.junit.Test;
 
+import static org.junit.Assert.assertTrue;
+
 /**
  * Examples of passwords conforming to various specifications, using different libraries.
  * 

core-java-modules/core-java-string-apis/src/test/java/com/baeldung/streamtokenizer/StreamTokenizerDemoUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.string.streamtokenizer;
+package com.baeldung.streamtokenizer;
 
 import org.junit.Test;
 

core-java-modules/core-java-string-apis/src/test/java/com/baeldung/stringjoiner/StringJoinerUnitTest.java

@@ -1,6 +1,6 @@
 package com.baeldung.stringjoiner;
 
-import static org.junit.Assert.assertEquals;
+import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -8,7 +8,7 @@ import java.util.List;
 import java.util.StringJoiner;
 import java.util.stream.Collectors;
 
-import org.junit.Test;
+import static org.junit.Assert.assertEquals;
 
 public class StringJoinerUnitTest {
     private final String DELIMITER_COMMA = ",";