Merge branch 'eugenp:master' into master

algorithms-modules/algorithms-miscellaneous-5/pom.xml

@@ -5,6 +5,18 @@
     <modelVersion>4.0.0</modelVersion>
     <artifactId>algorithms-miscellaneous-5</artifactId>
     <version>0.0.1-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>17</source>
+                    <target>17</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
     <name>algorithms-miscellaneous-5</name>
 
     <parent>

algorithms-modules/algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/conversion/HexStringConverter.java

@@ -1,15 +1,12 @@
 package com.baeldung.algorithms.conversion;
 
-import java.math.BigInteger;
-
-
-
+import com.google.common.io.BaseEncoding;
+import jakarta.xml.bind.DatatypeConverter;
 import org.apache.commons.codec.DecoderException;
 import org.apache.commons.codec.binary.Hex;
 
-import com.google.common.io.BaseEncoding;
-
-import jakarta.xml.bind.DatatypeConverter;
+import java.math.BigInteger;
+import java.util.HexFormat;
 
 public class HexStringConverter {
 
@@ -109,4 +106,14 @@ public class HexStringConverter {
         return BaseEncoding.base16()
             .decode(hexString.toUpperCase());
     }
+
+    public String encodeUsingHexFormat(byte[] bytes) {
+        HexFormat hexFormat = HexFormat.of();
+        return hexFormat.formatHex(bytes);
+    }
+
+    public byte[] decodeUsingHexFormat(String hexString) {
+        HexFormat hexFormat = HexFormat.of();
+        return hexFormat.parseHex(hexString);
+    }
 }

algorithms-modules/algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/conversion/ByteArrayConverterUnitTest.java

@@ -1,15 +1,13 @@
 package com.baeldung.algorithms.conversion;
 
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.junit.jupiter.api.Assertions.assertArrayEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-
 import org.apache.commons.codec.DecoderException;
 import org.hamcrest.text.IsEqualIgnoringCase;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import com.baeldung.algorithms.conversion.HexStringConverter;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 class ByteArrayConverterUnitTest {
 
@@ -24,7 +22,7 @@ class ByteArrayConverterUnitTest {
     void shouldEncodeByteArrayToHexStringUsingBigIntegerToString() {
         byte[] bytes = getSampleBytes();
         String hexString = getSampleHexString();
-        if(hexString.charAt(0) == '0') {
+        if (hexString.charAt(0) == '0') {
             hexString = hexString.substring(1);
         }
         String output = hexStringConverter.encodeUsingBigIntegerToString(bytes);
@@ -46,7 +44,7 @@ class ByteArrayConverterUnitTest {
         byte[] output = hexStringConverter.decodeUsingBigInteger(hexString);
         assertArrayEquals(bytes, output);
     }
-    
+
     @Test
     void shouldEncodeByteArrayToHexStringUsingCharacterConversion() {
         byte[] bytes = getSampleBytes();
@@ -62,7 +60,7 @@ class ByteArrayConverterUnitTest {
         byte[] output = hexStringConverter.decodeHexString(hexString);
         assertArrayEquals(bytes, output);
     }
-    
+
     @Test
     void shouldDecodeHexToByteWithInvalidHexCharacter() {
         assertThrows(IllegalArgumentException.class, () -> {
@@ -118,12 +116,28 @@ class ByteArrayConverterUnitTest {
         assertArrayEquals(bytes, output);
     }
 
+    @Test
+    void shouldEncodeByteArrayToHexStringUsingHexFormat() throws DecoderException {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        String output = hexStringConverter.encodeUsingHexFormat(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    void shouldDecodeHexStringToByteArrayUsingHexFormat() throws DecoderException {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        byte[] output = hexStringConverter.decodeUsingHexFormat(hexString);
+        assertArrayEquals(bytes, output);
+    }
+
     private String getSampleHexString() {
         return "0af50c0e2d10";
     }
 
     private byte[] getSampleBytes() {
-        return new byte[] { 10, -11, 12, 14, 45, 16 };
+        return new byte[]{10, -11, 12, 14, 45, 16};
     }
 
 }

algorithms-modules/algorithms-miscellaneous-7/README.md

@@ -10,8 +10,4 @@
 - [Check if Two Strings Are Rotations of Each Other](https://www.baeldung.com/java-string-check-strings-rotations)
 - [Find the Largest Prime Under the Given Number in Java](https://www.baeldung.com/java-largest-prime-lower-threshold)
 - [Count the Number of Unique Digits in an Integer using Java](https://www.baeldung.com/java-int-count-unique-digits)
-- [Generate Juggler Sequence in Java](https://www.baeldung.com/java-generate-juggler-sequence)
-- [Finding the Parent of a Node in a Binary Search Tree with Java](https://www.baeldung.com/java-find-parent-node-binary-search-tree)
-- [Check if a Number Is a Happy Number in Java](https://www.baeldung.com/java-happy-sad-number-test)
-- [Find the Largest Number Possible After Removing k Digits of a Number](https://www.baeldung.com/java-find-largest-number-remove-k-digits)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-6)

algorithms-modules/algorithms-miscellaneous-7/pom.xml

@@ -13,4 +13,22 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
+    <properties>
+        <jmh.version>1.35</jmh.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+    </dependencies>
+
 </project>

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/perfectnumber/PerfectNumber.java

@@ -0,0 +1,50 @@
+package com.baeldung.algorithms.perfectnumber;
+
+import java.util.stream.IntStream;
+
+class PerfectNumber {
+
+    public static boolean isPerfectBruteForce(int number) {
+        int sum = 0;
+        for (int i = 1; i <= number / 2; i++) {
+            if (number % i == 0) {
+                sum += i;
+            }
+        }
+        return sum == number;
+    }
+
+    public static boolean isPerfectStream(int number) {
+        int sum = IntStream.rangeClosed(2, (int) Math.sqrt(number))
+                .filter(test -> number % test == 0)
+                .reduce(1, (s, test) -> s + test + (number / test));
+        return sum == number;
+    }
+
+    public static boolean isPerfectEuclidEuler(int number) {
+        int p = 2;
+        int perfectNumber = (int) (Math.pow(2, p - 1) * (Math.pow(2, p) - 1));
+        while (perfectNumber <= number) {
+            if (perfectNumber == number) {
+                return true;
+            }
+            p++;
+            perfectNumber = (int) (Math.pow(2, p - 1) * (Math.pow(2, p) - 1));
+        }
+        return false;
+    }
+
+    public static boolean isPerfectEuclidEulerUsingShift(int number) {
+        int p = 2;
+        int perfectNumber = (2 << (p - 1)) * ((2 << p) - 1);
+        while (perfectNumber <= number) {
+            if (perfectNumber == number) {
+                return true;
+            }
+            p++;
+            perfectNumber = (2 << (p - 1)) * ((2 << p) - 1);
+        }
+        return false;
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/perfectnumber/PerfectNumberBenchmark.java

@@ -0,0 +1,41 @@
+package com.baeldung.algorithms.perfectnumber;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+@State(Scope.Benchmark)
+public class PerfectNumberBenchmark {
+
+    @Benchmark
+    public boolean bruteForceBenchmark() {
+        return PerfectNumber.isPerfectBruteForce(33550336);
+    }
+
+    @Benchmark
+    public boolean streamBenchmark() {
+        return PerfectNumber.isPerfectStream(33550336);
+    }
+
+    @Benchmark
+    public boolean euclidEulerBenchmark() {
+        return PerfectNumber.isPerfectEuclidEuler(33550336);
+    }
+
+    @Benchmark
+    public boolean euclidEulerUsingShiftBenchmark() {
+        return PerfectNumber.isPerfectEuclidEulerUsingShift(33550336);
+    }
+
+    public static void main(String[] args) throws Exception {
+        Options options = new OptionsBuilder()
+                .include(PerfectNumberBenchmark.class.getSimpleName())
+                .forks(1)
+                .build();
+
+        new Runner(options).run();
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/connect4/README.md

@@ -1,2 +0,0 @@
-## Relevant Articles
-- [Implement Connect 4 Game with Java](https://www.baeldung.com/java-connect-4-game)

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/perfectnumber/PerfectNumberUnitTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.algorithms.perfectnumber;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class PerfectNumberUnitTest {
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectBruteForce_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectBruteForce(6));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectBruteForce_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectBruteForce(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectBruteForce_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectBruteForce(-28));
+    }
+
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectStream_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectStream(28));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectStream_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectStream(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectStream_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectStream(-6));
+    }
+
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectEuclidEuler_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectEuclidEuler(28));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectEuclidEuler_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEuler(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectEuclidEuler_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEuler(-6));
+    }
+
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectEuclidEulerUsingShift(28));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEulerUsingShift(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEulerUsingShift(-6));
+    }
+}

algorithms-modules/algorithms-miscellaneous-8/README.md

@@ -0,0 +1,9 @@
+### Relevant Articles: 
+- [Vigenère Cipher in Java](https://www.baeldung.com/java-vigenere-cipher)
+- [Merge Overlapping Intervals in a Java Collection](https://www.baeldung.com/java-collection-merge-overlapping-intervals)
+- [Generate Juggler Sequence in Java](https://www.baeldung.com/java-generate-juggler-sequence)
+- [Finding the Parent of a Node in a Binary Search Tree with Java](https://www.baeldung.com/java-find-parent-node-binary-search-tree)
+- [Check if a Number Is a Happy Number in Java](https://www.baeldung.com/java-happy-sad-number-test)
+- [Find the Largest Number Possible After Removing k Digits of a Number](https://www.baeldung.com/java-find-largest-number-remove-k-digits)
+- [Implement Connect 4 Game with Java](https://www.baeldung.com/java-connect-4-game)
+- More articles: [[<-- prev]](/algorithms-miscellaneous-7)

algorithms-modules/algorithms-miscellaneous-8/src/main/java/com/baeldung/algorithms/largestNumberRemovingK/LargestNumberRemoveKDigits.java

@@ -1,6 +1,6 @@
 package com.baeldung.algorithms.largestNumberRemovingK;
 
-import java.util.*;
+import java.util.Stack;
 
 public class LargestNumberRemoveKDigits {
     public static int findLargestNumberUsingArithmetic(int num, int k) {

algorithms-modules/algorithms-miscellaneous-8/src/main/java/com/baeldung/algorithms/mergeintervals/Interval.java

@@ -0,0 +1,37 @@
+package com.baeldung.algorithms.mergeintervals;
+
+import java.util.Objects;
+
+public class Interval {
+    int start;
+    int end;
+
+    Interval(int start, int end) {
+        this.start = start;
+        this.end = end;
+    }
+
+    public void setEnd(int end) {
+        this.end = end;
+    }
+
+    @Override
+    public String toString() {
+        return "Interval{" + "start=" + start + ", end=" + end + '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Interval interval = (Interval) o;
+        return start == interval.start && end == interval.end;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(start, end);
+    }
+}

algorithms-modules/algorithms-miscellaneous-8/src/main/java/com/baeldung/algorithms/mergeintervals/MergeOverlappingIntervals.java

@@ -0,0 +1,29 @@
+package com.baeldung.algorithms.mergeintervals;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class MergeOverlappingIntervals {
+
+    public List<Interval> doMerge(List<Interval> intervals) {
+        // Sort the intervals based on start time
+        intervals.sort((one, two) -> one.start - two.start);
+
+        // Create somewhere to put the merged list, start it off with the earliest starting interval
+        ArrayList<Interval> merged = new ArrayList<>();
+        merged.add(intervals.get(0));
+
+        // Loop over each interval and merge if start time is before the end time of the
+        // previous interval
+        intervals.forEach(interval -> {
+            if (merged.get(merged.size() - 1).end > interval.start) {
+                merged.get(merged.size() - 1).setEnd(interval.end);
+            } else {
+                merged.add(interval);
+            }
+        });
+
+        return merged;
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-8/src/main/java/com/baeldung/algorithms/skiplist/Node.java

@@ -0,0 +1,11 @@
+package com.baeldung.algorithms.skiplist;
+
+class Node {
+    int value;
+    Node[] forward; // array to hold references to different levels
+
+    public Node(int value, int level) {
+        this.value = value;
+        this.forward = new Node[level + 1]; // level + 1 because level is 0-based
+    }
+}

algorithms-modules/algorithms-miscellaneous-8/src/main/java/com/baeldung/algorithms/skiplist/SkipList.java

@@ -0,0 +1,92 @@
+package com.baeldung.algorithms.skiplist;
+
+
+import java.util.Random;
+
+public class SkipList {
+    private Node head;
+    private int maxLevel;
+    private int level;
+    private Random random;
+
+    public SkipList() {
+        maxLevel = 16; // maximum number of levels
+        level = 0; // current level of SkipList
+        head = new Node(Integer.MIN_VALUE, maxLevel);
+        random = new Random();
+    }
+
+    public void insert(int value) {
+        Node[] update = new Node[maxLevel + 1];
+        Node current = this.head;
+
+        for (int i = level; i >= 0; i--) {
+            while (current.forward[i] != null && current.forward[i].value < value) {
+                current = current.forward[i];
+            }
+            update[i] = current;
+        }
+
+        current = current.forward[0];
+
+        if (current == null || current.value != value) {
+            int lvl = randomLevel();
+
+            if (lvl > level) {
+                for (int i = level + 1; i <= lvl; i++) {
+                    update[i] = head;
+                }
+                level = lvl;
+            }
+
+            Node newNode = new Node(value, lvl);
+            for (int i = 0; i <= lvl; i++) {
+                newNode.forward[i] = update[i].forward[i];
+                update[i].forward[i] = newNode;
+            }
+        }
+    }
+
+    public boolean search(int value) {
+        Node current = this.head;
+        for (int i = level; i >= 0; i--) {
+            while (current.forward[i] != null && current.forward[i].value < value) {
+                current = current.forward[i];
+            }
+        }
+        current = current.forward[0];
+        return current != null && current.value == value;
+    }
+
+    public void delete(int value) {
+        Node[] update = new Node[maxLevel + 1];
+        Node current = this.head;
+
+        for (int i = level; i >= 0; i--) {
+            while (current.forward[i] != null && current.forward[i].value < value) {
+                current = current.forward[i];
+            }
+            update[i] = current;
+        }
+        current = current.forward[0];
+
+        if (current != null && current.value == value) {
+            for (int i = 0; i <= level; i++) {
+                if (update[i].forward[i] != current) break;
+                update[i].forward[i] = current.forward[i];
+            }
+
+            while (level > 0 && head.forward[level] == null) {
+                level--;
+            }
+        }
+    }
+
+    private int randomLevel() {
+        int lvl = 0;
+        while (lvl < maxLevel && random.nextDouble() < 0.5) {
+            lvl++;
+        }
+        return lvl;
+    }
+}

algorithms-modules/algorithms-miscellaneous-8/src/test/java/com/baeldung/algorithms/happynumber/HappyNumberUnitTest.java

@@ -0,0 +1,82 @@
+package com.baeldung.algorithms.happynumber;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+class HappyNumberDecider {
+
+    public static boolean isHappyNumber(int n) {
+        Set<Integer> checkedNumbers = new HashSet<>();
+        while (true) {
+            n = sumDigitsSquare(n);
+            if (n == 1) {
+                return true;
+            }
+            if (checkedNumbers.contains(n)) {
+                return false;
+            }
+            checkedNumbers.add(n);
+        }
+    }
+
+    public static boolean isHappyNumberFloyd(int n) {
+        int slow = n;
+        int fast = n;
+        do {
+            slow = sumDigitsSquare(slow);
+            fast = sumDigitsSquare(sumDigitsSquare(fast));
+        } while (slow != fast);
+
+        return slow == 1;
+    }
+
+    private static int sumDigitsSquare(int n) {
+        int squareSum = 0;
+        while (n != 0) {
+            squareSum += (n % 10) * (n % 10);
+            n /= 10;
+        }
+        return squareSum;
+    }
+}
+
+public class HappyNumberUnitTest {
+
+    @Test
+    void whenUsingIsHappyNumber_thenGetTheExpectedResult() {
+        assertTrue(HappyNumberDecider.isHappyNumber(7));
+        assertTrue(HappyNumberDecider.isHappyNumber(10));
+        assertTrue(HappyNumberDecider.isHappyNumber(13));
+        assertTrue(HappyNumberDecider.isHappyNumber(19));
+        assertTrue(HappyNumberDecider.isHappyNumber(23));
+
+        assertFalse(HappyNumberDecider.isHappyNumber(4));
+        assertFalse(HappyNumberDecider.isHappyNumber(6));
+        assertFalse(HappyNumberDecider.isHappyNumber(11));
+        assertFalse(HappyNumberDecider.isHappyNumber(15));
+        assertFalse(HappyNumberDecider.isHappyNumber(20));
+
+    }
+
+    @Test
+    void whenUsingIsHappyNumber2_thenGetTheExpectedResult() {
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(7));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(10));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(13));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(19));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(23));
+
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(4));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(6));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(11));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(15));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(20));
+
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-8/src/test/java/com/baeldung/algorithms/mergeintervals/MergeIntervalsUnitTest.java

@@ -0,0 +1,30 @@
+package com.baeldung.algorithms.mergeintervals;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import org.junit.jupiter.api.Test;
+
+class MergeIntervalsUnitTest {
+
+    private ArrayList<Interval> intervals = new ArrayList<>(Arrays.asList(
+      new Interval(2, 5),
+      new Interval(13, 20),
+      new Interval(11, 15),
+      new Interval(1, 3)
+    ));
+    private ArrayList<Interval> intervalsMerged = new ArrayList<>(Arrays.asList(
+      new Interval(1, 5),
+      new Interval(11, 20)
+    ));
+
+    @Test
+    void givenIntervals_whenMerging_thenReturnMergedIntervals() {
+        MergeOverlappingIntervals merger = new MergeOverlappingIntervals();
+        ArrayList<Interval> result = (ArrayList<Interval>) merger.doMerge(intervals);
+        assertArrayEquals(intervalsMerged.toArray(), result.toArray());
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-8/src/test/java/com/baeldung/algorithms/parentnodebinarytree/BinaryTreeParentNodeFinderUnitTest.java

@@ -5,7 +5,9 @@ import org.junit.jupiter.api.Test;
 
 import java.util.NoSuchElementException;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
 class BinaryTreeParentNodeFinderUnitTest {
 

algorithms-modules/algorithms-miscellaneous-8/src/test/java/com/baeldung/algorithms/skiplist/SkipListUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.algorithms.skiplist;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SkipListUnitTest {
+
+    @Test
+    public void givenSkipList_WhenInsert_ThenSearchFound() {
+        SkipList skipList = new SkipList();
+
+        skipList.insert(3);
+        assertTrue(skipList.search(3), "Should find 3");
+
+        assertFalse(skipList.search(99), "Should not find 99");
+    }
+
+    @Test
+    public void givenSkipList_WhenDeleteElement_ThenRemoveFromList() {
+        SkipList skipList = new SkipList();
+
+        skipList.insert(3);
+        skipList.insert(7);
+
+        skipList.delete(3);
+        assertFalse(skipList.search(3), "3 should have been deleted");
+
+        skipList.delete(99);
+        assertTrue(skipList.search(7), "7 should still exist");
+    }
+
+}

apache-libraries-2/README.md

@@ -1,5 +1,6 @@
 ## Relevant Articles
 - [Understanding XSLT Processing in Java](https://www.baeldung.com/java-extensible-stylesheet-language-transformations)
 - [Add Camel Route at Runtime in Java](https://www.baeldung.com/java-camel-dynamic-route)
-
+- [Logging in Apache Camel](https://www.baeldung.com/java-apache-camel-logging)
 - More articles: [[<-- prev]](../apache-libraries)
+

apache-libraries-2/data/inbox/welcome.txt

@@ -0,0 +1 @@
+Welcome to Baeldung

apache-libraries-2/data/json/name.json

@@ -0,0 +1,4 @@
+{
+  "name" : "phillip",
+  "age" : 5
+}

apache-libraries-2/data/outbox/welcome.txt

@@ -0,0 +1 @@
+WELCOME TO BAELDUNG

apache-libraries-2/data/output/name.json

@@ -0,0 +1 @@
+{"name":"phillip","age":5,"transformedName":"PHILLIP","transformedAge":15}

apache-libraries-2/pom.xml

@@ -35,11 +35,16 @@
             <artifactId>camel-main</artifactId>
             <version>${camel.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.camel</groupId>
+            <artifactId>camel-jackson</artifactId>
+            <version>${camel.version}</version>
+        </dependency>
     </dependencies>
 
     <properties>
         <javax.validation.validation-api.version>2.0.1.Final</javax.validation.validation-api.version>
-        <camel.version>4.3.0</camel.version>
+        <camel.version>4.4.1</camel.version>
     </properties>
 
 </project>

apache-libraries-2/src/main/java/com/baeldung/apachecamellogging/CamelLoggingMainApp.java

@@ -0,0 +1,13 @@
+package com.baeldung.apachecamellogging;
+
+import org.apache.camel.main.Main;
+
+public class CamelLoggingMainApp {
+
+    public static void main(String[] args) throws Exception {
+        Main main = new Main();
+        main.configure()
+            .addRoutesBuilder(new FileCopierCamelRoute());
+        main.run(args);
+    }
+}

apache-libraries-2/src/main/java/com/baeldung/apachecamellogging/FileCopierCamelRoute.java

@@ -0,0 +1,25 @@
+package com.baeldung.apachecamellogging;
+
+import org.apache.camel.LoggingLevel;
+import org.apache.camel.builder.RouteBuilder;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class FileCopierCamelRoute extends RouteBuilder {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(FileCopierCamelRoute.class);
+
+    public void configure() {
+        from("file:data/inbox?noop=true").log("We got an incoming file ${file:name} containing: ${body}")
+            .to("log:com.baeldung.apachecamellogging?level=INFO")
+            .process(process -> {
+                LOGGER.info("We are passing the message to a FileProcesor bean to capitalize the message body");
+            })
+            .bean(FileProcessor.class)
+            .to("file:data/outbox")
+            .to("log:com.baeldung.apachecamellogging?showBodyType=false&maxChars=20")
+            .log(LoggingLevel.DEBUG, "Output Process", "The Process ${id}")
+            .log("Successfully transfer file: ${file:name}");
+    }
+}

apache-libraries-2/src/main/java/com/baeldung/apachecamellogging/FileCopierTracerCamelRoute.java

@@ -0,0 +1,22 @@
+package com.baeldung.apachecamellogging;
+
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.model.dataformat.JsonLibrary;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class FileCopierTracerCamelRoute extends RouteBuilder {
+
+    Logger logger = LoggerFactory.getLogger(FileCopierTracerCamelRoute.class);
+
+    public void configure() {
+        getContext().setTracing(true);
+        from("file:data/json?noop=true").to("log:input?level=INFO")
+            .unmarshal()
+            .json(JsonLibrary.Jackson)
+            .bean(FileProcessor.class, "transform")
+            .marshal()
+            .json(JsonLibrary.Jackson)
+            .to("file:data/output");
+    }
+}

apache-libraries-2/src/main/java/com/baeldung/apachecamellogging/FileProcessor.java

@@ -0,0 +1,23 @@
+package com.baeldung.apachecamellogging;
+
+import org.apache.camel.Body;
+
+import java.util.Map;
+
+public class FileProcessor {
+
+    public String process(@Body String fileContent) {
+        String processedContent = fileContent.toUpperCase();
+        return processedContent;
+    }
+
+    public Map<String, Object> transform(Map<String, Object> input) {
+        String name = (String) input.get("name");
+        int age = (int) input.get("age");
+
+        input.put("transformedName", name.toUpperCase());
+        input.put("transformedAge", age + 10);
+
+        return input;
+    }
+}

apache-libraries-2/src/test/java/com/baeldung/dynamicrouter/DynamicRouterRouteUnitTest.java

@@ -1,4 +1,4 @@
-package dynamicrouter;
+package com.baeldung.dynamicrouter;
 
 import com.baeldung.dynamicrouter.DynamicRouterRoute;
 import org.apache.camel.RoutesBuilder;

apache-poi/pom.xml

@@ -40,6 +40,16 @@
             <artifactId>fastexcel-reader</artifactId>
             <version>${fastexcel.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-api</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-core</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -64,6 +74,7 @@
         <jexcel.version>1.0.9</jexcel.version>
         <fastexcel.version>0.17.0</fastexcel.version>
         <maven.resources.plugin.version>3.3.1</maven.resources.plugin.version>
+        <log4j.version>2.23.1</log4j.version>
     </properties>
 
 </project>

aws-modules/aws-lambda-modules/todo-reminder-lambda/ToDoFunction/pom.xml

@@ -71,7 +71,7 @@
         <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-core</artifactId>
-            <version>${mockito-core.version}</version>
+            <version>${mockito.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -112,7 +112,6 @@
         <feign-core.version>11.2</feign-core.version>
         <guice.version>5.1.0</guice.version>
         <system-stubs-junit4.version>2.0.2</system-stubs-junit4.version>
-        <mockito-core.version>4.1.0</mockito-core.version>
         <assertj-core.version>3.19.0</assertj-core.version>
         <junit-jupiter.version>5.8.1</junit-jupiter.version>
     </properties>

azure/pom.xml

@@ -11,9 +11,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-boot-2</artifactId>
+        <artifactId>parent-boot-3</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-boot-2</relativePath>
+        <relativePath>../parent-boot-3</relativePath>
     </parent>
 
     <dependencies>
@@ -98,7 +98,7 @@
                         </property>
                         <property>
                             <name>spring.datasource.password</name>
-                            <value></value>
+                            <value>test</value>
                             <!--<value>replace-with-your-password</value> -->
                         </property>
                     </appSettings>
@@ -113,6 +113,14 @@
                     <!--</resource> -->
                     <!--</resources> -->
                 </configuration>
+                <dependencies>
+                    <!-- https://mvnrepository.com/artifact/javax.xml.bind/jaxb-api -->
+                    <dependency>
+                        <groupId>javax.xml.bind</groupId>
+                        <artifactId>jaxb-api</artifactId>
+                        <version>2.4.0-b180830.0359</version>
+                    </dependency>
+                </dependencies>
             </plugin>
         </plugins>
     </build>

azure/src/main/java/com/baeldung/springboot/azure/User.java

@@ -1,9 +1,9 @@
 package com.baeldung.springboot.azure;
 
-import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.GenerationType;
-import javax.persistence.Id;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
 
 /**
  * @author aiet

core-java-modules/core-java-11/src/main/java/com/baeldung/Unrelated.java

@@ -0,0 +1,4 @@
+package com.baeldung;
+
+public class Unrelated {
+}

core-java-modules/core-java-11/src/test/java/com/baeldung/OuterUnitTest.java

@@ -1,7 +1,7 @@
 package com.baeldung;
 
-import static org.junit.Assert.assertTrue;
 import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.*;
 
 import java.util.Arrays;
 import java.util.Set;
@@ -14,22 +14,22 @@ public class OuterUnitTest {
 
     @Test
     public void whenGetNestHostFromOuter_thenGetNestHost() {
-        is(Outer.class.getNestHost().getName()).equals(NEST_HOST_NAME);
+        assertEquals(NEST_HOST_NAME, Outer.class.getNestHost().getName());
     }
 
     @Test
     public void whenGetNestHostFromInner_thenGetNestHost() {
-        is(Outer.Inner.class.getNestHost().getName()).equals(NEST_HOST_NAME);
+        assertEquals(NEST_HOST_NAME, Outer.Inner.class.getNestHost().getName());
     }
 
     @Test
     public void whenCheckNestmatesForNestedClasses_thenGetTrue() {
-        is(Outer.Inner.class.isNestmateOf(Outer.class)).equals(true);
+        assertTrue(Outer.Inner.class.isNestmateOf(Outer.class));
     }
 
     @Test
     public void whenCheckNestmatesForUnrelatedClasses_thenGetFalse() {
-        is(Outer.Inner.class.isNestmateOf(Outer.class)).equals(false);
+        assertFalse(Outer.Inner.class.isNestmateOf(Unrelated.class));
     }
 
     @Test

core-java-modules/core-java-18/README.md

@@ -1,3 +1,4 @@
 ## Relevant Articles
 - [Deprecate Finalization in Java 18](https://www.baeldung.com/java-18-deprecate-finalization)
 - [Simple Web Server in Java 18](https://www.baeldung.com/simple-web-server-java-18)
+- [Internet Address Resolution SPI in Java](https://www.baeldung.com/java-service-provider-interface)

core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/InetAddressSPI.java

@@ -0,0 +1,44 @@
+package com.baeldung.inetspi;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Arrays;
+import java.util.stream.Stream;
+
+import com.baeldung.inetspi.providers.CustomAddressResolverImpl;
+
+public class InetAddressSPI {
+    public String usingGetByName(String host) throws UnknownHostException {
+        InetAddress inetAddress =  InetAddress.getByName(host);
+        return inetAddress.getHostAddress();
+    }
+
+    public String[] usingGetAllByName(String host) throws UnknownHostException {
+        InetAddress[] inetAddresses =  InetAddress.getAllByName(host);
+        return Arrays.stream(inetAddresses).map(InetAddress::getHostAddress).toArray(String[]::new);
+    }
+
+    public String usingGetByIp(byte[] ip) throws UnknownHostException {
+        InetAddress inetAddress =  InetAddress.getByAddress(ip);
+
+        return inetAddress.getHostName();
+    }
+
+    public String usingGetByIpAndReturnsCannonName(byte[] ip) throws UnknownHostException {
+        InetAddress inetAddress =  InetAddress.getByAddress(ip);
+
+        return inetAddress.getCanonicalHostName();
+    }
+
+    public String getHostUsingCustomImpl(byte[] ip) throws UnknownHostException {
+
+        CustomAddressResolverImpl imp = new CustomAddressResolverImpl();
+        return imp.get(null).lookupByAddress(ip);
+    }
+
+    public Stream<InetAddress> getIpUsingCustomImpl(String host) throws UnknownHostException {
+
+        CustomAddressResolverImpl imp = new CustomAddressResolverImpl();
+        return imp.get(null).lookupByName(host, null);
+    }
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/Registry.java

@@ -0,0 +1,56 @@
+package com.baeldung.inetspi;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.logging.Logger;
+import java.util.stream.Stream;
+
+public class Registry {
+    private final Map<String, List<byte[]>> registry;
+
+    private static final Logger LOGGER = Logger.getLogger(Registry.class.getName());
+
+    public Registry() {
+        registry = loadMapWithData();
+    }
+
+    public Stream<InetAddress> getAddressesfromHost(String host) throws UnknownHostException {
+        LOGGER.info("Performing Forward Lookup for HOST : " + host);
+        if (!registry.containsKey(host)) {
+            throw new UnknownHostException("Missing Host information in Resolver");
+        }
+        return registry.get(host)
+          .stream()
+          .map(add -> constructInetAddress(host, add))
+          .filter(Objects::nonNull);
+    }
+
+    public String getHostFromAddress(byte[] arr) throws UnknownHostException {
+        LOGGER.info("Performing Reverse Lookup for Address : " + Arrays.toString(arr));
+        for (Map.Entry<String, List<byte[]>> entry : registry.entrySet()) {
+            if (entry.getValue()
+              .stream()
+              .anyMatch(ba -> Arrays.equals(ba, arr))) {
+                return entry.getKey();
+            }
+        }
+        throw new UnknownHostException("Address Not Found");
+    }
+
+    private Map<String, List<byte[]>> loadMapWithData() {
+        return Map.of("baeldung-local.org", List.of(new byte[] { 1, 2, 3, 4 }));
+    }
+
+    private static InetAddress constructInetAddress(String host, byte[] address) {
+        try {
+            return InetAddress.getByAddress(host, address);
+        } catch (UnknownHostException unknownHostException) {
+            return null;
+        }
+    }
+
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/providers/CustomAddressResolverImpl.java

@@ -0,0 +1,42 @@
+package com.baeldung.inetspi.providers;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.net.spi.InetAddressResolver;
+import java.net.spi.InetAddressResolverProvider;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.logging.Logger;
+import java.util.stream.Stream;
+
+import com.baeldung.inetspi.Registry;
+
+public class CustomAddressResolverImpl extends InetAddressResolverProvider {
+
+    private static Logger LOGGER = Logger.getLogger(CustomAddressResolverImpl.class.getName());
+
+    private static Registry registry = new Registry();
+
+    @Override
+    public InetAddressResolver get(Configuration configuration) {
+        LOGGER.info("Using Custom Address Resolver :: " + this.name());
+        LOGGER.info("Registry initialised");
+        return new InetAddressResolver() {
+            @Override
+            public Stream<InetAddress> lookupByName(String host, LookupPolicy lookupPolicy) throws UnknownHostException {
+                return registry.getAddressesfromHost(host);
+            }
+
+            @Override
+            public String lookupByAddress(byte[] addr) throws UnknownHostException {
+                return registry.getHostFromAddress(addr);
+            }
+        };
+    }
+
+    @Override
+    public String name() {
+        return "CustomInternetAddressResolverImpl";
+    }
+}

core-java-modules/core-java-18/src/test/java/com/baeldung/inetspi/InetAddressSPIUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.inetspi;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.stream.Stream;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class InetAddressSPIUnitTest {
+    @Test
+    public void givenInetAddress_whenUsingInetAddress_thenPerformResolution() throws UnknownHostException {
+        InetAddressSPI spi = new InetAddressSPI();
+        Assert.assertNotNull(spi.usingGetByName("www.google.com"));
+        Assert.assertTrue(spi.usingGetAllByName("www.google.com").length > 1);
+        Assert.assertNotNull(spi.usingGetByIp(InetAddress.getByName("www.google.com")
+          .getAddress()));
+        Assert.assertNotNull(spi.usingGetByIpAndReturnsCannonName(InetAddress.getByName("www.google.com")
+          .getAddress()));
+    }
+
+    @Test
+    public void givenCustomInetAddressImplementation_whenUsingInetAddress_thenPerformResolution() throws UnknownHostException {
+        InetAddressSPI spi = new InetAddressSPI();
+        Assert.assertEquals("baeldung-local.org", spi.getHostUsingCustomImpl(new byte[] { 1, 2, 3, 4 }));
+        Stream<InetAddress> response = spi.getIpUsingCustomImpl("baeldung-local.org");
+        Assert.assertArrayEquals(new byte[] { 1, 2, 3, 4 }, response.findFirst()
+          .get()
+          .getAddress());
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/java21/PatternCaseLabels.java

@@ -0,0 +1,32 @@
+package com.baeldung.java21;
+
+public class PatternCaseLabels {
+
+    static String processInputOld(String input) {
+        String output;
+        switch (input) {
+        case null -> output = "Oops, null";
+        case String s -> {
+            if ("Yes".equalsIgnoreCase(s)) {
+                output = "It's Yes";
+            } else if ("No".equalsIgnoreCase(s)) {
+                output = "It's No";
+            } else {
+                output = "Try Again";
+            }
+        }
+        }
+        return output;
+    }
+
+    static String processInputNew(String input) {
+        String output;
+        switch (input) {
+        case null -> output = "Oops, null";
+        case String s when "Yes".equalsIgnoreCase(s) -> output = "It's Yes";
+        case String s when "No".equalsIgnoreCase(s) -> output = "It's No";
+        case String s -> output = "Try Again";
+        }
+        return output;
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/java21/RecordPattern.java

@@ -0,0 +1,36 @@
+package com.baeldung.java21;
+
+public class RecordPattern {
+
+    record Point(int x, int y) {}
+    
+    public static int beforeRecordPattern(Object obj) {
+        int sum = 0;
+        if(obj instanceof Point p) {
+            int x = p.x();
+            int y = p.y();
+            sum = x+y;
+        }
+        return sum;
+    }
+    
+    public static int afterRecordPattern(Object obj) {
+        if(obj instanceof Point(int x, int y)) {
+           return x+y;
+        }
+        return 0;
+    }
+    
+    enum Color {RED, GREEN, BLUE}
+    
+    record ColoredPoint(Point point, Color color) {}
+    
+    record RandomPoint(ColoredPoint cp) {}
+    
+    public static Color getRamdomPointColor(RandomPoint r) {
+        if(r instanceof RandomPoint(ColoredPoint cp)) {
+            return cp.color();
+        }
+        return null;
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/java21/StringTemplates.java

@@ -0,0 +1,9 @@
+package com.baeldung.java21;
+
+public class StringTemplates {
+
+    public String getStringTemplate() {
+        String name = "Baeldung"; 
+        return STR."Welcome to \{name}"; 
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/java21/SwitchPattern.java

@@ -0,0 +1,56 @@
+package com.baeldung.java21;
+
+public class SwitchPattern {
+    
+    static class Account{
+        double getBalance() {
+            return 0;
+        }
+    }
+    
+    static class SavingsAccount extends Account {
+        @Override
+        double getBalance() {
+            return 100;
+        } 
+    }
+    
+    static class TermAccount extends Account {
+        @Override
+        double getBalance() {
+            return 1000;
+        } 
+    }
+    static class CurrentAccount extends Account {
+        @Override
+        double getBalance() {
+            return 10000;
+        } 
+    }
+    
+    static double getBalanceWithOutSwitchPattern(Account account) {
+        double balance = 0;
+        if(account instanceof SavingsAccount sa) {
+            balance = sa.getBalance();
+        }
+        else if(account instanceof TermAccount ta) {
+            balance = ta.getBalance();
+        }
+        else if(account instanceof CurrentAccount ca) {
+            balance = ca.getBalance();
+        }
+        return balance;
+    }
+    
+    static double getBalanceWithSwitchPattern(Account account) {
+        double result;
+        switch (account) {
+            case null -> throw new IllegalArgumentException("Oops, account is null");
+            case SavingsAccount sa -> result = sa.getBalance();
+            case TermAccount ta -> result = ta.getBalance();
+            case CurrentAccount ca -> result = ca.getBalance();
+            default -> result = account.getBalance();
+        }
+        return result;
+    }
+}

core-java-modules/core-java-21/src/test/java/com/baeldung/java21/PatternCaseLabelsUnitTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.java21;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+class PatternCaseLabelsUnitTest {
+
+    @Test
+    void whenProcessInputOldWayWithYes_thenReturnOutput() {
+        assertEquals("It's Yes", PatternCaseLabels.processInputOld("Yes"));
+    }
+    
+    @Test
+    void whenProcessInputOldWayWithNo_thenReturnOutput() {
+        assertEquals("It's No", PatternCaseLabels.processInputOld("No"));
+    }
+    
+    @Test
+    void whenProcessInputOldWayWithNull_thenReturnOutput() {
+        assertEquals("Oops, null", PatternCaseLabels.processInputOld(null));
+    }
+    
+    @Test
+    void whenProcessInputOldWayWithInvalidOption_thenReturnOutput() {
+        assertEquals("Try Again", PatternCaseLabels.processInputOld("Invalid Option"));
+    }
+    
+    @Test
+    void whenProcessInputNewWayWithYes_thenReturnOutput() {
+        assertEquals("It's Yes", PatternCaseLabels.processInputNew("Yes"));
+    }
+    
+    @Test
+    void whenProcessInputNewWayWithNo_thenReturnOutput() {
+        assertEquals("It's No", PatternCaseLabels.processInputNew("No"));
+    }
+    
+    @Test
+    void whenProcessInputNewWayWithNull_thenReturnOutput() {
+        assertEquals("Oops, null", PatternCaseLabels.processInputNew(null));
+    }
+    
+    @Test
+    void whenProcessInputNewWayWithInvalidOption_thenReturnOutput() {
+        assertEquals("Try Again", PatternCaseLabels.processInputNew("Invalid Option"));
+    }
+   
+}

core-java-modules/core-java-21/src/test/java/com/baeldung/java21/RecordPatternUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.java21;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.java21.RecordPattern.Color;
+import com.baeldung.java21.RecordPattern.ColoredPoint;
+import com.baeldung.java21.RecordPattern.Point;
+import com.baeldung.java21.RecordPattern.RandomPoint;
+
+class RecordPatternUnitTest {
+
+    @Test
+    void whenNoRecordPattern_thenReturnOutput() {
+        assertEquals(5, RecordPattern.beforeRecordPattern(new Point(2, 3)));
+    }
+    
+    @Test
+    void whenRecordPattern_thenReturnOutput() {
+        assertEquals(5, RecordPattern.afterRecordPattern(new Point(2, 3)));
+    }
+    
+    @Test
+    void whenRecordPattern_thenReturnColorOutput() {
+        ColoredPoint coloredPoint = new ColoredPoint(new Point(2, 3), Color.GREEN);
+        RandomPoint randomPoint = new RandomPoint(coloredPoint);
+        assertEquals(Color.GREEN, RecordPattern.getRamdomPointColor(randomPoint));
+    }
+}

core-java-modules/core-java-21/src/test/java/com/baeldung/java21/StringTemplateUnitTest.java

@@ -0,0 +1,13 @@
+package com.baeldung.java21;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+class StringTemplateUnitTest {
+
+    @Test
+    void whenNoSwitchPattern_thenReturnSavingsAccountBalance() {
+        StringTemplates stringTemplates = new StringTemplates();
+        assertEquals("Welcome to Baeldung", stringTemplates.getStringTemplate());
+    }
+}

core-java-modules/core-java-21/src/test/java/com/baeldung/java21/SwitchPatternUnitTest.java

@@ -0,0 +1,19 @@
+package com.baeldung.java21;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+class SwitchPatternUnitTest {
+
+    @Test
+    void whenNoSwitchPattern_thenReturnSavingsAccountBalance() {
+        SwitchPattern.SavingsAccount savingsAccount = new SwitchPattern.SavingsAccount();
+        assertEquals(100, SwitchPattern.getBalanceWithOutSwitchPattern(savingsAccount), 0);
+    }
+    
+    @Test
+    void whenSwitchPattern_thenReturnSavingsAccountBalance() {
+        SwitchPattern.SavingsAccount savingsAccount = new SwitchPattern.SavingsAccount();
+        assertEquals(100, SwitchPattern.getBalanceWithSwitchPattern(savingsAccount), 0);
+    }
+}

core-java-modules/core-java-8-datetime-2/README.md

@@ -9,9 +9,4 @@
 - [Round the Date in Java](https://www.baeldung.com/java-round-the-date)
 - [Representing Furthest Possible Date in Java](https://www.baeldung.com/java-date-represent-max)
 - [Retrieving Unix Time in Java](https://www.baeldung.com/java-retrieve-unix-time)
-- [Calculate Months Between Two Dates in Java](https://www.baeldung.com/java-months-difference-two-dates)
-- [Format LocalDate to ISO 8601 With T and Z](https://www.baeldung.com/java-format-localdate-iso-8601-t-z)
-- [Check if Two Date Ranges Overlap](https://www.baeldung.com/java-check-two-date-ranges-overlap)
-- [Difference between ZoneOffset.UTC and ZoneId.of(“UTC”)](https://www.baeldung.com/java-zoneoffset-utc-zoneid-of)
-- [Check if a Given Time Lies Between Two Times Regardless of Date](https://www.baeldung.com/java-check-between-two-times)
-- [[<-- Prev]](/core-java-modules/core-java-datetime-java8-1)
+- [[<-- Prev]](/core-java-modules/core-java-datetime-java8-1) [[Next -->]](/core-java-modules/core-java-8-datetime-3)

core-java-modules/core-java-8-datetime-3/README.md

@@ -0,0 +1,8 @@
+### Relevant Articles:
+
+- [Calculate Months Between Two Dates in Java](https://www.baeldung.com/java-months-difference-two-dates)
+- [Format LocalDate to ISO 8601 With T and Z](https://www.baeldung.com/java-format-localdate-iso-8601-t-z)
+- [Check if Two Date Ranges Overlap](https://www.baeldung.com/java-check-two-date-ranges-overlap)
+- [Difference between ZoneOffset.UTC and ZoneId.of(“UTC”)](https://www.baeldung.com/java-zoneoffset-utc-zoneid-of)
+- [Check if a Given Time Lies Between Two Times Regardless of Date](https://www.baeldung.com/java-check-between-two-times)
+- [[<-- Prev]](/core-java-modules/core-java-8-datetime-2)

core-java-modules/core-java-8-datetime-3/pom.xml

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-8-datetime-3</artifactId>
+    <packaging>jar</packaging>
+    <name>core-java-8-datetime-3</name>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>joda-time</groupId>
+            <artifactId>joda-time</artifactId>
+            <version>${joda-time.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <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>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <joda-time.version>2.12.5</joda-time.version>
+    </properties>
+
+</project>

core-java-modules/core-java-8-datetime-3/src/main/java/com/baeldung/daterangeoverlap/DateRangeOverlapChecker.java

@@ -1,11 +1,11 @@
 package com.baeldung.daterangeoverlap;
 
-import java.time.LocalDate;
-import java.util.Calendar;
-
 import org.joda.time.DateTime;
 import org.joda.time.Interval;
 
+import java.time.LocalDate;
+import java.util.Calendar;
+
 public class DateRangeOverlapChecker {
 
     public static boolean isOverlapUsingCalendarAndDuration(Calendar start1, Calendar end1, Calendar start2, Calendar end2) {

core-java-modules/core-java-8-datetime-3/src/main/java/com/baeldung/localdatetoiso/LocalDateToISO.java

@@ -1,20 +1,16 @@
 package com.baeldung.localdatetoiso;
 
+import org.apache.commons.lang3.time.FastDateFormat;
+import org.joda.time.DateTimeZone;
+import org.joda.time.format.ISODateTimeFormat;
+
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.time.LocalDate;
 import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
 import java.util.Date;
-
-import org.apache.commons.lang3.time.DateFormatUtils;
-
-import org.joda.time.DateTime;
-import org.joda.time.DateTimeZone;
-import org.joda.time.format.DateTimeFormat;
-import org.joda.time.format.ISODateTimeFormat;
-
-import org.apache.commons.lang3.time.FastDateFormat;
+import java.util.TimeZone;
 
 public class LocalDateToISO {
     public String formatUsingDateTimeFormatter(LocalDate localDate) {

core-java-modules/core-java-8-datetime-3/src/test/java/com/baeldung/checkiftimebetweentwotimes/CheckIfTimeBetweenTwoTimesUnitTest.java

@@ -1,45 +1,45 @@
-package com.baeldung.checkiftimebetweentwotimes;
-
-import org.junit.Test;
-
-import java.time.LocalTime;
-import java.util.Calendar;
-import java.util.Date;
-
-import static org.junit.Assert.assertTrue;
-
-public class CheckIfTimeBetweenTwoTimesUnitTest {
-    private LocalTime startTime = LocalTime.parse("09:00:00");
-    private LocalTime endTime = LocalTime.parse("17:00:00");
-    private LocalTime targetTime = LocalTime.parse("12:30:00");
-
-    @Test
-    public void givenLocalTime_whenUsingIsAfterIsBefore_thenTimeIsBetween() {
-        assertTrue(!targetTime.isBefore(startTime) && !targetTime.isAfter(endTime));
-    }
-
-    @Test
-    public void givenLocalTime_whenUsingCompareTo_thenTimeIsBetween() {
-        assertTrue(targetTime.compareTo(startTime) >= 0 && targetTime.compareTo(endTime) <= 0);
-    }
-
-    @Test
-    public void givenDate_whenUsingAfterBefore_thenTimeIsBetween() {
-        Calendar startCalendar = Calendar.getInstance();
-        startCalendar.set(Calendar.HOUR_OF_DAY, 9);
-        startCalendar.set(Calendar.MINUTE, 0);
-        Date startTime = startCalendar.getTime();
-
-        Calendar endCalendar = Calendar.getInstance();
-        endCalendar.set(Calendar.HOUR_OF_DAY, 17);
-        endCalendar.set(Calendar.MINUTE, 0);
-        Date endTime = endCalendar.getTime();
-
-        Calendar targetCalendar = Calendar.getInstance();
-        targetCalendar.set(Calendar.HOUR_OF_DAY, 12);
-        targetCalendar.set(Calendar.MINUTE, 30);
-        Date targetTime = targetCalendar.getTime();
-
-        assertTrue(!targetTime.before(startTime) && !targetTime.after(endTime));
-    }
+package com.baeldung.checkiftimebetweentwotimes;
+
+import org.junit.Test;
+
+import java.time.LocalTime;
+import java.util.Calendar;
+import java.util.Date;
+
+import static org.junit.Assert.assertTrue;
+
+public class CheckIfTimeBetweenTwoTimesUnitTest {
+    private LocalTime startTime = LocalTime.parse("09:00:00");
+    private LocalTime endTime = LocalTime.parse("17:00:00");
+    private LocalTime targetTime = LocalTime.parse("12:30:00");
+
+    @Test
+    public void givenLocalTime_whenUsingIsAfterIsBefore_thenTimeIsBetween() {
+        assertTrue(!targetTime.isBefore(startTime) && !targetTime.isAfter(endTime));
+    }
+
+    @Test
+    public void givenLocalTime_whenUsingCompareTo_thenTimeIsBetween() {
+        assertTrue(targetTime.compareTo(startTime) >= 0 && targetTime.compareTo(endTime) <= 0);
+    }
+
+    @Test
+    public void givenDate_whenUsingAfterBefore_thenTimeIsBetween() {
+        Calendar startCalendar = Calendar.getInstance();
+        startCalendar.set(Calendar.HOUR_OF_DAY, 9);
+        startCalendar.set(Calendar.MINUTE, 0);
+        Date startTime = startCalendar.getTime();
+
+        Calendar endCalendar = Calendar.getInstance();
+        endCalendar.set(Calendar.HOUR_OF_DAY, 17);
+        endCalendar.set(Calendar.MINUTE, 0);
+        Date endTime = endCalendar.getTime();
+
+        Calendar targetCalendar = Calendar.getInstance();
+        targetCalendar.set(Calendar.HOUR_OF_DAY, 12);
+        targetCalendar.set(Calendar.MINUTE, 30);
+        Date targetTime = targetCalendar.getTime();
+
+        assertTrue(!targetTime.before(startTime) && !targetTime.after(endTime));
+    }
 }

core-java-modules/core-java-8-datetime-3/src/test/java/com/baeldung/daterangeoverlap/DateRangeOverlapCheckerUnitTest.java

@@ -1,13 +1,13 @@
 package com.baeldung.daterangeoverlap;
 
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import org.joda.time.DateTime;
+import org.junit.Test;
 
 import java.time.LocalDate;
 import java.util.Calendar;
 
-import org.joda.time.DateTime;
-import org.junit.Test;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 public class DateRangeOverlapCheckerUnitTest {
 

core-java-modules/core-java-8-datetime-3/src/test/java/com/baeldung/localdatetoiso/LocalDateToISOUnitTest.java

@@ -1,13 +1,14 @@
 package com.baeldung.localdatetoiso;
 
+import org.junit.Test;
+
+import java.time.LocalDate;
+
 import static org.junit.Assert.assertEquals;
 
-import org.junit.Test;
-import java.time.LocalDate;
-
 public class LocalDateToISOUnitTest {
     @Test
-    void givenLocalDate_whenUsingDateTimeFormatter_thenISOFormat(){
+    public void givenLocalDate_whenUsingDateTimeFormatter_thenISOFormat(){
         LocalDateToISO localDateToISO = new LocalDateToISO();
         LocalDate localDate = LocalDate.of(2023, 11, 6);
 
@@ -17,7 +18,7 @@ public class LocalDateToISOUnitTest {
     }
 
     @Test
-    void givenLocalDate_whenUsingSimpleDateFormat_thenISOFormat(){
+    public void givenLocalDate_whenUsingSimpleDateFormat_thenISOFormat(){
         LocalDateToISO localDateToISO = new LocalDateToISO();
         LocalDate localDate = LocalDate.of(2023, 11, 6);
 
@@ -27,17 +28,18 @@ public class LocalDateToISOUnitTest {
     }
 
     @Test
-    void givenLocalDate_whenUsingJodaTime_thenISOFormat() {
+    public void givenLocalDate_whenUsingJodaTime_thenISOFormat() {
         LocalDateToISO localDateToISO = new LocalDateToISO();
         org.joda.time.LocalDate localDate = new org.joda.time.LocalDate(2023, 11, 6);
 
         String expected = "2023-11-06T00:00:00.000Z";
         String actual = localDateToISO.formatUsingJodaTime(localDate);
         assertEquals(expected, actual);
+        assertEquals(expected, actual);
     }
 
     @Test
-    void givenLocalDate_whenUsingApacheCommonsLang_thenISOFormat() {
+    public void givenLocalDate_whenUsingApacheCommonsLang_thenISOFormat() {
         LocalDateToISO localDateToISO = new LocalDateToISO();
         LocalDate localDate = LocalDate.of(2023, 11, 6);
 

core-java-modules/core-java-8-datetime-3/src/test/java/com/baeldung/zoneoffsetandzoneidof/ZoneOffSetAndZoneIdOfUnitTest.java

@@ -1,25 +1,25 @@
-package com.baeldung.zoneoffsetandzoneidof;
-
-import org.junit.jupiter.api.Test;
-
-import java.time.OffsetDateTime;
-import java.time.ZoneId;
-import java.time.ZoneOffset;
-import java.time.ZonedDateTime;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-public class ZoneOffSetAndZoneIdOfUnitTest {
-
-    @Test
-    public void givenOffsetDateTimeWithUTCZoneOffset_thenOffsetShouldBeUTC() {
-        OffsetDateTime dateTimeWithOffset = OffsetDateTime.now(ZoneOffset.UTC);
-        assertEquals(dateTimeWithOffset.getOffset(), ZoneOffset.UTC);
-    }
-
-    @Test
-    public void givenZonedDateTimeWithUTCZoneId_thenZoneShouldBeUTC() {
-        ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of("UTC"));
-        assertEquals(zonedDateTime.getZone(), ZoneId.of("UTC"));
-    }
-}
+package com.baeldung.zoneoffsetandzoneidof;
+
+import org.junit.jupiter.api.Test;
+
+import java.time.OffsetDateTime;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ZoneOffSetAndZoneIdOfUnitTest {
+
+    @Test
+    public void givenOffsetDateTimeWithUTCZoneOffset_thenOffsetShouldBeUTC() {
+        OffsetDateTime dateTimeWithOffset = OffsetDateTime.now(ZoneOffset.UTC);
+        assertEquals(dateTimeWithOffset.getOffset(), ZoneOffset.UTC);
+    }
+
+    @Test
+    public void givenZonedDateTimeWithUTCZoneId_thenZoneShouldBeUTC() {
+        ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of("UTC"));
+        assertEquals(zonedDateTime.getZone(), ZoneId.of("UTC"));
+    }
+}

core-java-modules/core-java-collections-5/README.md

@@ -9,9 +9,9 @@
 - [Skipping the First Iteration in Java](https://www.baeldung.com/java-skip-first-iteration)
 - [Remove Elements From a Queue Using Loop](https://www.baeldung.com/java-remove-elements-queue)
 - [Intro to Vector Class in Java](https://www.baeldung.com/java-vector-guide)
-- [HashSet toArray() Method in Java](https://www.baeldung.com/java-hashset-toarray)
 - [Time Complexity of Java Collections Sort in Java](https://www.baeldung.com/java-time-complexity-collections-sort)
 - [Check if List Contains at Least One Enum](https://www.baeldung.com/java-list-check-enum-presence)
 - [Comparison of for Loops and Iterators](https://www.baeldung.com/java-for-loops-vs-iterators)
 - [PriorityQueue iterator() Method in Java](https://www.baeldung.com/java-priorityqueue-iterator)
+- [Immutable vs Unmodifiable Collection in Java](https://www.baeldung.com/java-collection-immutable-unmodifiable-differences)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-4)

core-java-modules/core-java-collections-5/pom.xml

@@ -55,8 +55,8 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
-                    <source>9</source>
-                    <target>9</target>
+                    <source>16</source>
+                    <target>16</target>
                 </configuration>
             </plugin>
         </plugins>

core-java-modules/core-java-collections-5/src/test/java/com/baeldung/immutables/ImmutableCollectionsUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.immutables;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+class ImmutableCollectionsUnitTest {
+
+    @Test
+    void givenUnmodifiableMap_whenPutNewEntry_thenThrowsUnsupportedOperationException() {
+        Map<String, String> modifiableMap = new HashMap<>();
+        modifiableMap.put("name1", "Michael");
+        modifiableMap.put("name2", "Harry");
+
+        Map<String, String> unmodifiableMap = Collections.unmodifiableMap(modifiableMap);
+
+        assertThrows(UnsupportedOperationException.class, () -> unmodifiableMap.put("name3", "Micky"));
+    }
+
+    @Test
+    void givenUnmodifiableMap_whenPutNewEntryUsingOriginalReference_thenSuccess() {
+        Map<String, String> modifiableMap = new HashMap<>();
+        modifiableMap.put("name1", "Michael");
+        modifiableMap.put("name2", "Harry");
+
+        Map<String, String> unmodifiableMap = Collections.unmodifiableMap(modifiableMap);
+        modifiableMap.put("name3", "Micky");
+
+        assertEquals(modifiableMap, unmodifiableMap);
+        assertTrue(unmodifiableMap.containsKey("name3"));
+    }
+
+    @Test
+    void givenImmutableMap_whenPutNewEntry_thenThrowsUnsupportedOperationException() {
+        Map<String, String> immutableMap = Map.of("name1", "Michael", "name2", "Harry");
+
+        assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("name3", "Micky"));
+    }
+
+    @Test
+    void givenImmutableMap_whenUsecopyOf_thenExceptionOnPut() {
+        Map<String, String> immutableMap = Map.of("name1", "Michael", "name2", "Harry");
+        Map<String, String> copyOfImmutableMap = Map.copyOf(immutableMap);
+
+        assertThrows(UnsupportedOperationException.class, () -> copyOfImmutableMap.put("name3", "Micky"));
+    }
+}
+

core-java-modules/core-java-collections-6/README.md

@@ -0,0 +1,7 @@
+=========
+
+## Core Java Collections Cookbooks and Examples
+
+### Relevant Articles:
+
+- More articles: [[<-- prev]](/core-java-modules/core-java-collections-5)

core-java-modules/core-java-collections-6/pom.xml

@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    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-collections-6</artifactId>
+    <packaging>jar</packaging>
+    <name>core-java-collections-6</name>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-runner</artifactId>
+            <version>${junit-platform.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.vintage</groupId>
+            <artifactId>junit-vintage-engine</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.roaringbitmap</groupId>
+            <artifactId>RoaringBitmap</artifactId>
+            <version>${roaringbitmap.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>9</source>
+                    <target>9</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <junit.version>5.9.2</junit.version>
+        <roaringbitmap.version>0.9.38</roaringbitmap.version>
+        <jmh.version>1.36</jmh.version>
+    </properties>
+
+</project>

core-java-modules/core-java-collections-6/src/test/java/com/baeldung/iteratorvsforeach/IteratorVsForeachUnitTest.java

@@ -0,0 +1,64 @@
+package com.baeldung.iteratorvsforeach;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertIterableEquals;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+class IteratorVsForeachUnitTest {
+
+    private static Stream<Arguments> listProvider() {
+        return Stream.of(Arguments.of(List.of("String1", "String2", "unwanted"), List.of("String1", "String2")));
+    }
+
+    @Test
+    public void givenEmptyCollection_whenUsingForEach_thenNoElementsAreIterated() {
+        List<String> names = Collections.emptyList();
+        StringBuilder stringBuilder = new StringBuilder();
+        names.forEach(stringBuilder::append);
+        assertEquals("", stringBuilder.toString());
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    public void givenCollectionWithElements_whenRemovingElementDuringForEachIteration_thenElementIsRemoved(List<String> input, List<String> expected) {
+        List<String> mutableList = new ArrayList<>(input);
+        // Separate collection for items to be removed
+        List<String> toRemove = new ArrayList<>();
+
+        // Using forEach to identify items to remove
+        input.forEach(item -> {
+            if (item.equals("unwanted")) {
+                toRemove.add(item);
+            }
+        });
+
+        // Removing the identified items from the original list
+        mutableList.removeAll(toRemove);
+        assertIterableEquals(expected, mutableList);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    public void givenCollectionWithElements_whenRemovingElementDuringIteratorIteration_thenElementIsRemoved(List<String> input, List<String> expected) {
+        List<String> mutableList = new ArrayList<>(input);
+        Iterator<String> it = mutableList.iterator();
+        while (it.hasNext()) {
+            String item = it.next();
+            if (item.equals("unwanted")) {
+                it.remove(); // Safely remove item
+            }
+        }
+        assertIterableEquals(expected, mutableList);
+    }
+
+}

core-java-modules/core-java-collections-6/src/test/java/com/baeldung/listiteration/ListIterationUnitTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.listiteration;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertIterableEquals;
+
+public class ListIterationUnitTest {
+
+    List<String> programmingLanguages = new ArrayList<>(List.of("Java", "Python", "C++"));
+    List<Integer> numbers = new ArrayList<>(List.of(1, 2, 3));
+
+   @Test
+    public void givenStringList_whenAddElementWithListIterator_thenModifiedList() {
+        ListIterator<String> listIterator = programmingLanguages.listIterator();
+        while (listIterator.hasNext()) {
+            String language = listIterator.next();
+            if (language.equals("Python")) {
+                listIterator.add("JavaScript");
+            }
+        }
+
+        assertIterableEquals(Arrays.asList("Java", "Python", "JavaScript", "C++"), programmingLanguages);
+    }
+
+    @Test
+    public void givenNumericalList_whenMultiplyElementWithListIterator_thenModifiedList() {
+        ListIterator<Integer> listIterator = numbers.listIterator();
+        while (listIterator.hasNext()) {
+            int num = listIterator.next();
+            if (num == 2) {
+                listIterator.add(num * 10);
+            }
+        }
+        assertIterableEquals(Arrays.asList(1, 2, 20, 3), numbers);
+    }
+
+    @Test
+    public void givenStringList_whenAddElementWithEnhancedForLoopAndCopy_thenModifiedList() {
+        List<String> copyOfWords = new ArrayList<>(programmingLanguages);
+        for (String word : copyOfWords) {
+            programmingLanguages.add(word.toUpperCase()); // Modified: Convert to uppercase
+        }
+        assertIterableEquals(Arrays.asList("Java", "Python", "C++", "JAVA", "PYTHON", "C++"), programmingLanguages);
+    }
+
+    @Test
+    public void givenNumericalList_whenMultiplyElementWithEnhancedForLoopAndCopy_thenModifiedList() {
+        List<Integer> copyOfNumbers = new ArrayList<>(numbers);
+        for (int num : copyOfNumbers) {
+            numbers.add(num * 2);
+        }
+        assertIterableEquals(Arrays.asList(1, 2, 3, 2, 4, 6), numbers);
+    }
+
+    @Test
+    public void givenStringList_whenConvertToUpperCaseWithJava8Stream_thenModifiedList() {
+        programmingLanguages = programmingLanguages.stream().map(String::toUpperCase).collect(Collectors.toList());
+        assertIterableEquals(Arrays.asList("JAVA", "PYTHON", "C++"), programmingLanguages);
+    }
+
+    @Test
+    public void givenNumericalList_whenMultiplyByThreeWithJava8Stream_thenModifiedList() {
+        numbers = numbers.stream().map(num -> num * 3).collect(Collectors.toList());
+        assertIterableEquals(Arrays.asList(3, 6, 9), numbers);
+    }
+
+}

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

@@ -5,3 +5,4 @@ This module contains articles about conversions among Collection types in Java.
 ### Relevant Articles:
 - [Converting HashMap Values to an ArrayList in Java](https://www.baeldung.com/java-hashmap-arraylist)
 - [Joining a List<String> in Java With Commas and “and”](https://www.baeldung.com/java-string-concatenation-natural-language)
+- [HashSet toArray() Method in Java](https://www.baeldung.com/java-hashset-toarray)

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

@@ -1,59 +0,0 @@
-package com.baeldung.java.listInitialization;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
-import lombok.extern.java.Log;
-
-import org.junit.Assert;
-import org.junit.Test;
-
-@Log
-public class ListInitializationUnitTest {
-
-    @Test
-    public void givenAnonymousInnerClass_thenInitialiseList() {
-        List<String> cities = new ArrayList() {
-            {
-                add("New York");
-                add("Rio");
-                add("Tokyo");
-            }
-        };
-
-        Assert.assertTrue(cities.contains("New York"));
-    }
-
-    @Test
-    public void givenArraysAsList_thenInitialiseList() {
-        List<String> list = Arrays.asList("foo", "bar");
-
-        Assert.assertTrue(list.contains("foo"));
-    }
-
-    @Test(expected = UnsupportedOperationException.class)
-    public void givenArraysAsList_whenAdd_thenUnsupportedException() {
-        List<String> list = Arrays.asList("foo", "bar");
-
-        list.add("baz");
-    }
-
-    @Test
-    public void givenArraysAsList_whenCreated_thenShareReference() {
-        String[] array = { "foo", "bar" };
-        List<String> list = Arrays.asList(array);
-        array[0] = "baz";
-        Assert.assertEquals("baz", list.get(0));
-    }
-
-    @Test
-    public void givenStream_thenInitializeList() {
-        List<String> list = Stream.of("foo", "bar")
-            .collect(Collectors.toList());
-
-        Assert.assertTrue(list.contains("foo"));
-    }
-}

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

@@ -0,0 +1,91 @@
+package com.baeldung.java.listinitialization;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+
+import lombok.extern.java.Log;
+
+@Log
+public class ListInitializationUnitTest {
+
+    @Test
+    public void givenAnonymousInnerClass_thenInitialiseList() {
+        List<String> cities = new ArrayList() {
+            {
+                add("New York");
+                add("Rio");
+                add("Tokyo");
+            }
+        };
+
+        assertTrue(cities.contains("New York"));
+    }
+
+    @Test
+    public void givenArraysAsList_thenInitialiseList() {
+        List<String> list = Arrays.asList("foo", "bar");
+
+        assertTrue(list.contains("foo"));
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void givenArraysAsList_whenAdd_thenUnsupportedException() {
+        List<String> list = Arrays.asList("foo", "bar");
+
+        list.add("baz");
+    }
+
+    @Test
+    public void givenArraysAsList_whenUsingArrayListConstructor_thenWeCanAddOrRemove() {
+        List<String> list = new ArrayList<>(Arrays.asList("foo", "bar"));
+
+        list.add("baz");
+        assertEquals(List.of("foo", "bar","baz"), list);
+        
+        list.remove("baz");
+        assertEquals(List.of("foo", "bar"), list);
+    }
+
+    @Test
+    public void givenArraysAsList_whenCreated_thenShareReference() {
+        String[] array = { "foo", "bar" };
+        List<String> list = Arrays.asList(array);
+        array[0] = "baz";
+        assertEquals("baz", list.get(0));
+    }
+
+    @Test
+    public void givenIntNumbers_whenRequiredLong_thenCastAutomatically() {
+        int intNum = 42;
+        long longNum = intNum;
+
+        assertEquals(42L, longNum);
+    }
+
+    @Test
+    public void givenArrayAsList_whenRequiredLongList_thenGetExpectedResult() {
+        List<Long> listOfLongFixedSize = Arrays.asList(1L, 2L, 3L);
+        List<Long> listOfLong = new ArrayList<>(Arrays.asList(1L, 2L, 3L));
+
+        List<Long> expected = List.of(1L, 2L, 3L);
+
+        assertEquals(expected, listOfLongFixedSize);
+        assertEquals(expected, listOfLong);
+    }
+
+    @Test
+    public void givenStream_thenInitializeList() {
+        List<String> list = Stream.of("foo", "bar")
+            .collect(Collectors.toList());
+
+        assertTrue(list.contains("foo"));
+    }
+}

core-java-modules/core-java-collections-list-6/README.md

@@ -5,3 +5,4 @@
 - [Sorting One List Based on Another List in Java](https://www.baeldung.com/java-sorting-one-list-using-another)
 - [Reset ListIterator to First Element of the List in Java](https://www.baeldung.com/java-reset-listiterator)
 - [Modify and Print List Items With Java Streams](https://www.baeldung.com/java-stream-list-update-print-elements)
+- [Add One Element to an Immutable List in Java](https://www.baeldung.com/java-immutable-list-add-element)

core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/addtoimmutablelist/AddElementsToImmutableListUnitTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.addtoimmutablelist;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+public class AddElementsToImmutableListUnitTest {
+
+    public static <T> List<T> appendAnElement(List<T> immutableList, T element) {
+        List<T> tmpList = new ArrayList<>(immutableList);
+        tmpList.add(element);
+        return Collections.unmodifiableList(tmpList);
+    }
+
+    @SafeVarargs
+    public static <T> List<T> appendElements(List<T> immutableList, T... elements) {
+        List<T> tmpList = new ArrayList<>(immutableList);
+        tmpList.addAll(Arrays.asList(elements));
+        return Collections.unmodifiableList(tmpList);
+    }
+
+    @Test
+    void whenCallingAppendAnElement_thenGetExpectedResult() {
+        List<String> myList = List.of("A", "B", "C", "D", "E");
+        List<String> expected = List.of("A", "B", "C", "D", "E", "F");
+        List<String> result = appendAnElement(myList, "F");
+        assertThat(result).isEqualTo(expected)
+            .isUnmodifiable();
+    }
+
+    @Test
+    void whenCallingAppendElements_thenGetExpectedResult() {
+        List<String> myList = List.of("A", "B", "C", "D", "E");
+        List<String> expected1 = List.of("A", "B", "C", "D", "E", "F");
+        List<String> result1 = appendElements(myList, "F");
+        assertThat(result1).isEqualTo(expected1)
+            .isUnmodifiable();
+
+        List<String> expected2 = List.of("A", "B", "C", "D", "E", "F", "G", "H", "I");
+        List<String> result2 = appendElements(myList, "F", "G", "H", "I");
+        assertThat(result2).isEqualTo(expected2)
+            .isUnmodifiable();
+    }
+}

core-java-modules/core-java-collections-maps-8/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [Find Map Keys with Duplicate Values in Java](https://www.baeldung.com/java-map-find-keys-repeated-values)

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

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-collections-maps-8</artifactId>
+    <name>core-java-collections-maps-8</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <artifactId>core-java-modules</artifactId>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <configuration>
+                    <argLine>
+                        --add-opens java.base/java.util=ALL-UNNAMED
+                    </argLine>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

core-java-modules/core-java-collections-maps-8/src/test/java/com/baeldung/map/valuetokeyset/ConvertMapKeyValueToMapValueKeySetUnitTest.java

@@ -0,0 +1,127 @@
+package com.baeldung.map.valuetokeyset;
+
+import static java.util.stream.Collectors.collectingAndThen;
+import static java.util.stream.Collectors.groupingBy;
+import static java.util.stream.Collectors.mapping;
+import static java.util.stream.Collectors.toSet;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Multimaps;
+import com.google.common.collect.SetMultimap;
+
+public class ConvertMapKeyValueToMapValueKeySetUnitTest {
+
+    private static final Map<String, String> INPUT_MAP = Map.of(
+        // @formatter:off
+        "Kai", "Linux",
+        "Eric", "MacOS",
+        "Kevin", "Windows",
+        "Liam", "MacOS",
+        "David", "Linux",
+        "Saajan", "Windows",
+        "Loredana", "MacOS"
+        // @formatter:on
+    );
+
+    private static final Map<String, Set<String>> EXPECTED = Map.of(
+        // @formatter:off
+        "Linux", Set.of("Kai", "David"),
+        "Windows", Set.of("Saajan", "Kevin"),
+        "MacOS", Set.of("Eric", "Liam", "Loredana")
+        // @formatter:on
+    );
+
+    private static final Map<String, String> INPUT_MAP_WITH_NULLS = new HashMap<String, String>(INPUT_MAP) {{
+        put("Tom", null);
+        put("Jerry", null);
+        put(null, null);
+    }};
+
+    private static final Map<String, Set<String>> EXPECTED_WITH_NULLS = new HashMap<String, Set<String>>(EXPECTED) {{
+        put(null, new HashSet<String>() {{
+            add("Tom");
+            add("Jerry");
+            add(null);
+        }});
+    }};
+
+    public static <K, V> Map<V, Set<K>> transformMap(Map<K, V> input) {
+        Map<V, Set<K>> resultMap = new HashMap<>();
+        for (Map.Entry<K, V> entry : input.entrySet()) {
+            if (!resultMap.containsKey(entry.getValue())) {
+                resultMap.put(entry.getValue(), new HashSet<>());
+            }
+            resultMap.get(entry.getValue())
+                .add(entry.getKey());
+        }
+        return resultMap;
+    }
+
+    @Test
+    void whenUsingClassicLoopBasedSolution_thenGetExpectedResult() {
+        Map<String, Set<String>> result = transformMap(INPUT_MAP);
+        assertEquals(EXPECTED, result);
+
+        Map<String, Set<String>> result2 = transformMap(INPUT_MAP_WITH_NULLS);
+        assertEquals(EXPECTED_WITH_NULLS, result2);
+    }
+
+    @Test
+    void whenUsingJava8StreamGroupingBy_thenGetExpectedResult() {
+        Map<String, Set<String>> result = INPUT_MAP.entrySet()
+            .stream()
+            .collect(groupingBy(Map.Entry::getValue, mapping(Map.Entry::getKey, toSet())));
+        assertEquals(EXPECTED, result);
+
+        assertThrows(NullPointerException.class, () -> INPUT_MAP_WITH_NULLS.entrySet()
+            .stream()
+            .collect(groupingBy(Map.Entry::getValue, mapping(Map.Entry::getKey, toSet()))));
+    }
+
+    @Test
+    void whenUsingJava8ForEach_thenGetExpectedResult() {
+        Map<String, Set<String>> result = new HashMap<>();
+        INPUT_MAP.forEach((key, value) -> result.computeIfAbsent(value, k -> new HashSet<>())
+            .add(key));
+        assertEquals(EXPECTED, result);
+
+        Map<String, Set<String>> result2 = new HashMap<>();
+        INPUT_MAP_WITH_NULLS.forEach((key, value) -> result2.computeIfAbsent(value, k -> new HashSet<>())
+            .add(key));
+        assertEquals(EXPECTED_WITH_NULLS, result2);
+    }
+
+    @Test
+    void whenUsingGuavaMultiMapCollector_thenGetExpectedResult() {
+        Map<String, Set<String>> result = INPUT_MAP.entrySet()
+            .stream()
+            .collect(collectingAndThen(Multimaps.toMultimap(Map.Entry::getValue, Map.Entry::getKey, HashMultimap::create), Multimaps::asMap));
+        assertEquals(EXPECTED, result);
+
+        Map<String, Set<String>> result2 = INPUT_MAP_WITH_NULLS.entrySet()
+            .stream()
+            .collect(collectingAndThen(Multimaps.toMultimap(Map.Entry::getValue, Map.Entry::getKey, HashMultimap::create), Multimaps::asMap));
+        assertEquals(EXPECTED_WITH_NULLS, result2);
+    }
+
+    @Test
+    void whenUsingGuavaInvertFromAndForMap_thenGetExpectedResult() {
+        SetMultimap<String, String> multiMap = Multimaps.invertFrom(Multimaps.forMap(INPUT_MAP), HashMultimap.create());
+        Map<String, Set<String>> result = Multimaps.asMap(multiMap);
+        assertEquals(EXPECTED, result);
+
+        SetMultimap<String, String> multiMapWithNulls = Multimaps.invertFrom(Multimaps.forMap(INPUT_MAP_WITH_NULLS), HashMultimap.create());
+        Map<String, Set<String>> result2 = Multimaps.asMap(multiMapWithNulls);
+        assertEquals(EXPECTED_WITH_NULLS, result2);
+    }
+
+}

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

@@ -6,4 +6,5 @@
 - [How to Get First Item From a Java Set](https://www.baeldung.com/first-item-set)
 - [Cartesian Product of Any Number of Sets in Java](https://www.baeldung.com/java-cartesian-product-sets)
 - [How to Get Index of an Item in Java Set](https://www.baeldung.com/java-set-element-find-index)
+- [Check if an Element Is Present in a Set in Java](https://www.baeldung.com/java-set-membership)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-set)

core-java-modules/core-java-collections-set-2/src/test/java/com/baeldung/checkifpresentinset/CheckIfPresentInSetUnitTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.checkifpresentinset;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.apache.commons.collections4.CollectionUtils;
+import org.apache.commons.collections4.SetUtils;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class CheckIfPresentInSetUnitTest {
+
+    private static final Set<String> CITIES = new HashSet<>();
+
+    @BeforeAll
+    static void setup() {
+        CITIES.add("Paris");
+        CITIES.add("London");
+        CITIES.add("Tokyo");
+        CITIES.add("Tamassint");
+        CITIES.add("New york");
+    }
+
+    @Test
+    void givenASet_whenUsingStreamAnyMatchMethod_thenCheck() {
+        boolean isPresent = CITIES.stream()
+            .anyMatch(city -> city.equals("London"));
+
+        assertThat(isPresent).isTrue();
+    }
+
+    @Test
+    void givenASet_whenUsingStreamFilterMethod_thenCheck() {
+        long resultCount = CITIES.stream()
+            .filter(city -> city.equals("Tamassint"))
+            .count();
+
+        assertThat(resultCount).isPositive();
+    }
+
+    @Test
+    void givenASet_whenUsingContainsMethod_thenCheck() {
+        assertThat(CITIES.contains("London")).isTrue();
+        assertThat(CITIES.contains("Madrid")).isFalse();
+    }
+
+    @Test
+    void givenASet_whenUsingCollectionsDisjointMethod_thenCheck() {
+        boolean isPresent = !Collections.disjoint(CITIES, Collections.singleton("Paris"));
+
+        assertThat(isPresent).isTrue();
+    }
+
+    @Test
+    void givenASet_whenUsingCollectionUtilsContainsAnyMethod_thenCheck() {
+        boolean isPresent = CollectionUtils.containsAny(CITIES, Collections.singleton("Paris"));
+
+        assertThat(isPresent).isTrue();
+    }
+
+    @Test
+    void givenASet_whenUsingSetUtilsIntersectionMethod_thenCheck() {
+        Set<String> result = SetUtils.intersection(CITIES, Collections.singleton("Tamassint"));
+
+        assertThat(result).isNotEmpty();
+    }
+
+}

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

@@ -86,7 +86,7 @@
         <maven.compiler.target>1.8</maven.compiler.target>
         <jcabi-aspects.version>0.22.6</jcabi-aspects.version>
         <aspectjrt.version>1.9.20.1</aspectjrt.version>
-        <cactoos.version>0.43</cactoos.version>
+        <cactoos.version>0.55.0</cactoos.version>
         <ea-async.version>1.2.3</ea-async.version>
         <jcabi-maven-plugin.version>0.14.1</jcabi-maven-plugin.version>
         <aspectjtools.version>1.9.20.1</aspectjtools.version>

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

@@ -5,3 +5,4 @@ This module contains articles about converting between Java date and time object
 ### Relevant Articles: 
 - [Convert Gregorian to Hijri Date in Java](https://www.baeldung.com/java-date-gregorian-hijri-conversion)
 - [Convert String Date to XMLGregorianCalendar in Java](https://www.baeldung.com/java-string-date-xmlgregoriancalendar-conversion)
+- [Convert TemporalAccessor to LocalDate](https://www.baeldung.com/java-temporalaccessor-localdate-conversion)

core-java-modules/core-java-datetime-conversion-2/src/test/java/com/baeldung/TemporalAccessorToLocalDate/TemporalAccessorToLocalDateUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.TemporalAccessorToLocalDate;
+
+import org.junit.Test;
+
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.TemporalAccessor;
+import java.time.temporal.TemporalQueries;
+
+import static org.junit.Assert.assertEquals;
+
+public class TemporalAccessorToLocalDateUnitTest {
+    String dateString = "2022-03-28";
+    TemporalAccessor temporalAccessor = DateTimeFormatter.ISO_LOCAL_DATE.parse(dateString);
+
+    @Test
+    public void givenTemporalAccessor_whenUsingLocalDateFrom_thenConvertToLocalDate() {
+        LocalDate convertedDate = LocalDate.from(temporalAccessor);
+        assertEquals(LocalDate.of(2022, 3, 28), convertedDate);
+    }
+
+    @Test
+    public void givenTemporalAccessor_whenUsingTemporalQueries_thenConvertToLocalDate() {
+        int year = temporalAccessor.query(TemporalQueries.localDate()).getYear();
+        int month = temporalAccessor.query(TemporalQueries.localDate()).getMonthValue();
+        int day = temporalAccessor.query(TemporalQueries.localDate()).getDayOfMonth();
+
+        LocalDate convertedDate = LocalDate.of(year, month, day);
+        assertEquals(LocalDate.of(2022, 3, 28), convertedDate);
+    }
+}

core-java-modules/core-java-io-5/README.md

@@ -10,5 +10,7 @@ This module contains articles about core Java input and output (IO)
 - [Read a File and Split It Into Multiple Files in Java](https://www.baeldung.com/java-read-file-split-into-several)
 - [Read and Write Files in Java Using Separate Threads](https://www.baeldung.com/java-read-write-files-different-threads)
 - [Convert an OutputStream to a Byte Array in Java](https://www.baeldung.com/java-outputstream-byte-array)
+- [Reading a .gz File Line by Line Using GZIPInputStream](https://www.baeldung.com/java-gzipinputstream-read-gz-file-line-by-line)
+- [Opening HTML File Using Java](https://www.baeldung.com/java-open-html-file)
 - [[<-- Prev]](/core-java-modules/core-java-io-4)
 

core-java-modules/core-java-io-5/src/test/java/com/baeldung/com.baeldung.openhtmlfiles/OpenHtmlFilesUnitTest.java

@@ -0,0 +1,45 @@
+package com.baeldung.openhtmlfiles;
+
+import org.junit.Test;
+
+import java.awt.*;
+import java.io.File;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.net.URL;
+
+import static org.junit.Assert.*;
+
+public class OpenHtmlFilesUnitTest {
+    public URL url;
+    public String absolutePath;
+
+    public OpenHtmlFilesUnitTest() throws URISyntaxException {
+        url = getClass().getResource("/test.html");
+        assert url != null;
+        File file = new File(url.toURI());
+        if (!file.exists()) {
+            fail();
+        }
+        absolutePath = file.getAbsolutePath();
+    }
+    /*
+    @Test
+    public void givenHtmlFile_whenUsingDesktopClass_thenOpenFileInDefaultBrowser() throws IOException {
+        File htmlFile = new File(absolutePath);
+        Desktop.getDesktop().browse(htmlFile.toURI());
+        assertTrue(true);
+    }
+    */
+    @Test
+    public void givenHtmlFile_whenUsingProcessBuilder_thenOpenFileInDefaultBrowser() throws IOException {
+        ProcessBuilder pb;
+        if (System.getProperty("os.name").toLowerCase().contains("win")) {
+            pb = new ProcessBuilder("cmd.exe", "/c", "start", absolutePath);
+        } else {
+            pb = new ProcessBuilder("xdg-open", absolutePath);
+        }
+        pb.start();
+        assertTrue(true);
+    }
+}

core-java-modules/core-java-io-5/src/test/java/com/baeldung/printwriterwritevsprint/WriteVsPrintUnitTest.java

@@ -0,0 +1,113 @@
+package com.baeldung.printwriterwritevsprint;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.io.*;
+import java.util.*;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class WriteVsPrintUnitTest {
+
+    Object outputFromPrintWriter;
+    Object outputFromPrintWriter() {
+        try (BufferedReader br = new BufferedReader(new FileReader("output.txt"))){
+            outputFromPrintWriter = br.readLine();
+        } catch (IOException e){
+            e.printStackTrace();
+            Assertions.fail();
+        }
+        return outputFromPrintWriter;
+    }
+
+    @Test
+    void whenUsingWriteInt_thenASCIICharacterIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        printWriter.write(48);
+        printWriter.close();
+
+        assertEquals("0", outputFromPrintWriter());
+    }
+
+    @Test
+    void whenUsingWriteCharArrayFromOffset_thenCharArrayIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        printWriter.write(new char[]{'A','/','&','4','E'}, 1, 4 );
+        printWriter.close();
+
+        assertEquals("/&4E", outputFromPrintWriter());
+    }
+
+    @Test
+    void whenUsingWriteStringFromOffset_thenLengthOfStringIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        printWriter.write("StringExample", 6, 7 );
+        printWriter.close();
+
+        assertEquals("Example", outputFromPrintWriter());
+    }
+
+    @Test
+    void whenUsingPrintBoolean_thenStringValueIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        printWriter.print(true);
+        printWriter.close();
+
+        assertEquals("true", outputFromPrintWriter());
+    }
+
+    @Test
+    void whenUsingPrintChar_thenCharIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        printWriter.print('A');
+        printWriter.close();
+
+        assertEquals("A", outputFromPrintWriter());
+    }
+
+    @Test
+    void whenUsingPrintInt_thenValueOfIntIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        printWriter.print(420);
+        printWriter.close();
+
+        assertEquals("420", outputFromPrintWriter());
+    }
+
+    @Test
+    void whenUsingPrintString_thenStringIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        printWriter.print("RandomString");
+        printWriter.close();
+
+        assertEquals("RandomString", outputFromPrintWriter());
+    }
+
+    @Test
+    void whenUsingPrintObject_thenObjectToStringIsPrinted() throws FileNotFoundException {
+
+        PrintWriter printWriter = new PrintWriter("output.txt");
+
+        Map example = new HashMap();
+
+        printWriter.print(example);
+        printWriter.close();
+
+        assertEquals(example.toString(), outputFromPrintWriter());
+    }
+}

core-java-modules/core-java-io-5/src/test/resources/test.html

@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<meta charset="utf-8">
+	<meta name="viewport" content="width=device-width, initial-scale=1">
+	<title>
+		
+
+	</title>
+</head>
+<body>
+
+	<h1>Hello dear friend</h1>
+</body>
+</html>

core-java-modules/core-java-io-apis-2/README.md

@@ -11,3 +11,5 @@ This module contains articles about core Java input/output(IO) APIs.
 - [PrintWriter vs. FileWriter in Java](https://www.baeldung.com/java-printwriter-filewriter-difference)
 - [Read Input Character-by-Character in Java](https://www.baeldung.com/java-read-input-character)
 - [Difference Between flush() and close() in Java FileWriter](https://www.baeldung.com/java-filewriter-flush-vs-close)
+- [Get a Path to a Resource in a Java JAR File](https://www.baeldung.com/java-get-path-resource-jar)
+- [Java InputStream vs. InputStreamReader](https://www.baeldung.com/java-inputstream-vs-inputstreamreader)

core-java-modules/core-java-io-apis-2/pom.xml

@@ -20,28 +20,6 @@
             <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter-engine</artifactId>
-            <version>5.7.2</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-        </dependency>
         <!-- this is all you need to write tests with JUnit Jupiter -->
         <dependency>
             <groupId>org.junit.jupiter</groupId>
@@ -63,18 +41,6 @@
             <version>${junit-jupiter-version}</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-        </dependency>
         <dependency>
             <groupId>org.testng</groupId>
             <artifactId>testng</artifactId>
@@ -96,4 +62,5 @@
     <properties>
         <junit-jupiter-version>5.9.3</junit-jupiter-version>
     </properties>
-</project>
+
+</project>

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/getpathtoresource/GetPathToResourceUnitTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.getpathtoresource;
+
+import org.junit.Test;
+
+import java.net.URL;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Objects;
+
+import static org.junit.Assert.assertNotNull;
+
+public class GetPathToResourceUnitTest {
+
+    @Test
+    public void givenFile_whenClassUsed_thenGetResourcePath() {
+        URL resourceUrl = GetPathToResourceUnitTest.class.getResource("/sampleText1.txt");
+        assertNotNull(resourceUrl);
+    }
+
+    @Test
+    public void givenFile_whenClassLoaderUsed_thenGetResourcePath() {
+        URL resourceUrl = GetPathToResourceUnitTest.class.getClassLoader().getResource("sampleText1.txt");
+        assertNotNull(resourceUrl);
+    }
+
+    @Test
+    public void givenFile_whenPathUsed_thenGetResourcePath() throws Exception {
+        Path resourcePath = Paths.get(Objects.requireNonNull(GetPathToResourceUnitTest.class.getResource("/sampleText1.txt")).toURI());
+        assertNotNull(resourcePath);
+    }
+
+}

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/inputstreamreader/InputStreamReaderUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.inputstreamreader;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+public class InputStreamReaderUnitTest {
+    @Test
+    public void givenAStringWrittenToAFile_whenReadByInputStreamReader_thenShouldMatchWhenRead(@TempDir Path tempDir) throws IOException {
+        String sampleTxt = "Good day. This is just a test. Good bye.";
+        Path sampleOut = tempDir.resolve("sample-out.txt");
+        List<String> lines = Arrays.asList(sampleTxt);
+        Files.write(sampleOut, lines);
+        String absolutePath = String.valueOf(sampleOut.toAbsolutePath());
+        try (InputStreamReader reader = new InputStreamReader(new FileInputStream(absolutePath), StandardCharsets.UTF_8)) {
+            boolean isMatched = false;
+            int b;
+            StringBuilder sb = new StringBuilder();
+            while ((b = reader.read()) != -1) {
+                sb.append((char) b);
+                if (sb.toString().contains(sampleTxt)) {
+                    isMatched = true;
+                    break;
+                }
+            }
+            assertThat(isMatched).isTrue();
+        }
+    }
+}

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

@@ -260,7 +260,6 @@
         <!-- util -->
         <unix4j.version>0.4</unix4j.version>
         <grep4j.version>1.8.7</grep4j.version>
-        <mockito.version>4.6.1</mockito.version>
         <!-- maven plugins -->
         <javamoney.moneta.version>1.1</javamoney.moneta.version>
         <maven-javadoc-plugin.version>3.6.2</maven-javadoc-plugin.version>

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

@@ -7,15 +7,11 @@
 - [Evaluating a Math Expression in Java](https://www.baeldung.com/java-evaluate-math-expression-string)
 - [Swap Two Variables in Java](https://www.baeldung.com/java-swap-two-variables)
 - [Java Program to Find the Roots of a Quadratic Equation](https://www.baeldung.com/roots-quadratic-equation)
-- [Create a BMI Calculator in Java](https://www.baeldung.com/java-body-mass-index-calculator)
 - [Java Program to Calculate the Standard Deviation](https://www.baeldung.com/java-calculate-standard-deviation)
 - [Java Program to Print Pascal’s Triangle](https://www.baeldung.com/java-pascal-triangle)
 - [Java Money and the Currency API](http://www.baeldung.com/java-money-and-currency)
 - [Clamp Function in Java](https://www.baeldung.com/java-clamp-function)
 - [Creating a Magic Square in Java](https://www.baeldung.com/java-magic-square)
-- [Check if a Point Is Between Two Points Drawn on a Straight Line in Java](https://www.baeldung.com/java-check-point-straight-line)
 - [Validate if a String Is a Valid Geo Coordinate](https://www.baeldung.com/java-geo-coordinates-validation)
-- [Rotate a Vertex Around a Certain Point in Java](https://www.baeldung.com/java-rotate-vertex-around-point)
 - [Calculating the Power of Any Number in Java Without Using Math pow() Method](https://www.baeldung.com/java-calculating-the-power-without-math-pow)
-- [Solving Rod Cutting Problem in Java](https://www.baeldung.com/java-rod-cutting-problem)
 - More articles: [[<-- Prev]](/core-java-modules/core-java-lang-math-2)

core-java-modules/core-java-lang-math-4/README.md

@@ -2,3 +2,7 @@
 
 ### Relevant articles:
 - [Calculate Percentiles in Java](https://www.baeldung.com/java-compute-percentiles)
+- [Solving Rod Cutting Problem in Java](https://www.baeldung.com/java-rod-cutting-problem)
+- [Rotate a Vertex Around a Certain Point in Java](https://www.baeldung.com/java-rotate-vertex-around-point)
+- [Create a BMI Calculator in Java](https://www.baeldung.com/java-body-mass-index-calculator)
+- [Check if a Point Is Between Two Points Drawn on a Straight Line in Java](https://www.baeldung.com/java-check-point-straight-line)