Merge branch 'eugenp:master' into PR-6910

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/rotatearray/RotateArray.java

@@ -0,0 +1,102 @@
+package com.baeldung.algorithms.rotatearray;
+
+/**
+ *  To speed up the rotation, we narrow k rotations to the remainder of k divided by the array length, or k module the array length.
+ *  Therefore, a large rotation number will be translated into the relative smallest rotation.
+ *  All solutions replace the original array, although they might use an extra array to compute the rotation.
+ */
+public class RotateArray {
+
+    private RotateArray() {
+        throw new IllegalStateException("Rotate array algorithm utility methods class");
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void bruteForce(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k %= arr.length;
+        int temp;
+        int previous;
+        for (int i = 0; i < k; i++) {
+            previous = arr[arr.length - 1];
+            for (int j = 0; j < arr.length; j++) {
+                temp = arr[j];
+                arr[j] = previous;
+                previous = temp;
+            }
+        }
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void withExtraArray(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        int[] extraArray = new int[arr.length];
+        for (int i = 0; i < arr.length; i++) {
+            extraArray[(i + k) % arr.length] = arr[i];
+        }
+        System.arraycopy(extraArray, 0, arr, 0, arr.length);
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void cyclicReplacement(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k = k % arr.length;
+        int count = 0;
+        for (int start = 0; count < arr.length; start++) {
+            int current = start;
+            int prev = arr[start];
+            do {
+                int next = (current + k) % arr.length;
+                int temp = arr[next];
+                arr[next] = prev;
+                prev = temp;
+                current = next;
+                count++;
+            } while (start != current);
+        }
+    }
+
+    /**
+     *
+     * @param arr array to apply rotation to
+     * @param k number of rotations
+     */
+    public static void reverse(int[] arr, int k) {
+        checkInvalidInput(arr, k);
+
+        k %= arr.length;
+        reverse(arr, 0, arr.length - 1);
+        reverse(arr, 0, k - 1);
+        reverse(arr, k, arr.length - 1);
+    }
+
+    private static void reverse(int[] nums, int start, int end) {
+        while (start < end) {
+            int temp = nums[start];
+            nums[start] = nums[end];
+            nums[end] = temp;
+            start++;
+            end--;
+        }
+    }
+
+    private static void checkInvalidInput(int[] arr, int rotation) {
+        if (rotation < 1 || arr == null)
+            throw new IllegalArgumentException("Rotation must be greater than zero or array must be not null");
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/rotatearray/RotateArrayUnitTest.java

@@ -0,0 +1,124 @@
+package com.baeldung.algorithms.rotatearray;
+
+import static com.baeldung.algorithms.rotatearray.RotateArray.bruteForce;
+import static com.baeldung.algorithms.rotatearray.RotateArray.cyclicReplacement;
+import static com.baeldung.algorithms.rotatearray.RotateArray.reverse;
+import static com.baeldung.algorithms.rotatearray.RotateArray.withExtraArray;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class RotateArrayUnitTest {
+
+    private final int[] arr = { 1, 2, 3, 4, 5, 6 };
+    private final int rotationLtArrayLength = 1;
+    private final int rotationGtArrayLength = arr.length + 2;
+    private final int[] ltArrayLengthRotation = { 6, 1, 2, 3, 4, 5 };
+    private final int[] gtArrayLengthRotation = { 5, 6, 1, 2, 3, 4 };
+
+    @Test
+    void givenInputArray_whenNoRotationOrEmptyArray_thenThrowIllegalArgumentException() {
+        final int noRotation = 0;
+        final int someRotation = arr.length - 1;
+
+        assertThrows(IllegalArgumentException.class, () -> bruteForce(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> withExtraArray(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(arr, noRotation));
+        assertThrows(IllegalArgumentException.class, () -> reverse(arr, noRotation));
+
+        assertThrows(IllegalArgumentException.class, () -> bruteForce(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> withExtraArray(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> cyclicReplacement(null, someRotation));
+        assertThrows(IllegalArgumentException.class, () -> reverse(null, someRotation));
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationLtArrayLength_thenRotateArrayOk() {
+
+        bruteForce(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationGtArrayLength_thenRotateArrayOk() {
+
+        bruteForce(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseBruteForceRotationEqArrayLength_thenDoNothing() {
+        int[] expected = arr.clone();
+
+        bruteForce(arr, arr.length);
+        assertArrayEquals(expected, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayRotationLtArrayLength_thenRotateArrayOk() {
+
+        withExtraArray(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayRotationGtArrayLength_thenRotateArrayOk() {
+
+        withExtraArray(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseExtraArrayWithRotationEqArrayLength_thenDoNothing() {
+        int[] clone = arr.clone();
+
+        withExtraArray(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationLtArrayLength_thenRotateArrayOk() {
+
+        cyclicReplacement(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationGtArrayLength_thenRotateArrayOk() {
+
+        cyclicReplacement(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseCyclicReplacementRotationEqArrayLength_thenDoNothing() {
+        int[] clone = arr.clone();
+
+        cyclicReplacement(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationLtArrayLength_thenRotateArrayOk() {
+
+        reverse(arr, rotationLtArrayLength);
+        assertArrayEquals(ltArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationGtArrayLength_thenRotateArrayOk() {
+
+        reverse(arr, rotationGtArrayLength);
+        assertArrayEquals(gtArrayLengthRotation, arr);
+    }
+
+    @Test
+    void givenInputArray_whenUseReverseRotationEqArrayLength_thenDoNothing() {
+
+        int[] clone = arr.clone();
+
+        reverse(arr, arr.length);
+        assertArrayEquals(clone, arr);
+    }
+}

apache-kafka-2/README.md

@@ -13,3 +13,4 @@ You can build the project from the command line using: *mvn clean install*, or i
 - [Read Data From the Beginning Using Kafka Consumer API](https://www.baeldung.com/java-kafka-consumer-api-read)
 - [Get Partition Count for a Topic in Kafka](https://www.baeldung.com/java-kafka-partition-count-topic)
 - [bootstrap-server in Kafka Configuration](https://www.baeldung.com/java-kafka-bootstrap-server)
+- [Introduction to Apache Kafka](https://www.baeldung.com/apache-kafka)

apache-kafka-2/src/test/java/com/baeldung/kafka/multipletopics/MultipleTopicsLiveTest.java

@@ -0,0 +1,103 @@
+package com.baeldung.kafka.multipletopics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Properties;
+import java.util.concurrent.ExecutionException;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+// This live test needs a Docker Daemon running so that a kafka container can be created
+
+@Testcontainers
+public class MultipleTopicsLiveTest {
+
+    private final Logger log = LoggerFactory.getLogger(MultipleTopicsLiveTest.class);
+
+    private static final String CARD_PAYMENTS_TOPIC = "card-payments";
+    private static final String BANK_TRANSFERS_TOPIC = "bank-transfers";
+    private static KafkaProducer<String, String> producer;
+    private static KafkaConsumer<String, String> consumer;
+
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+
+    @BeforeAll
+    static void setup() {
+        KAFKA_CONTAINER.addExposedPort(9092);
+        producer = new KafkaProducer<>(getProducerProperties());
+        consumer = new KafkaConsumer<>(getConsumerProperties());
+    }
+
+    @AfterAll
+    static void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    private static Properties getProducerProperties() {
+        Properties producerProperties = new Properties();
+        producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        return producerProperties;
+    }
+
+    private static Properties getConsumerProperties() {
+        Properties consumerProperties = new Properties();
+        consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "payments");
+        return consumerProperties;
+    }
+
+    @Test
+    void whenSendingMessagesOnTwoTopics_thenConsumerReceivesMessages() throws Exception {
+        publishMessages();
+
+        consumer.subscribe(Arrays.asList(CARD_PAYMENTS_TOPIC, BANK_TRANSFERS_TOPIC));
+
+        int eventsProcessed = 0;
+        for (ConsumerRecord<String, String> record : consumer.poll(Duration.ofSeconds(10))) {
+            log.info("Event on topic={}, payload={}", record.topic(), record.value());
+            eventsProcessed++;
+        }
+
+        assertThat(eventsProcessed).isEqualTo(2);
+    }
+
+    private void publishMessages() throws ExecutionException, InterruptedException {
+        ProducerRecord<String, String> cardPayment = new ProducerRecord<>(CARD_PAYMENTS_TOPIC, createCardPayment());
+        producer.send(cardPayment).get();
+
+        ProducerRecord<String, String> bankTransfer = new ProducerRecord<>(BANK_TRANSFERS_TOPIC, createBankTransfer());
+        producer.send(bankTransfer).get();
+    }
+
+    private String createCardPayment() {
+        return "{\"paymentReference\":\"A184028KM0013790\", \"type\":\"card\", \"amount\":\"275\", \"currency\":\"GBP\"}";
+    }
+
+    private String createBankTransfer() {
+        return "{\"paymentReference\":\"19ae2-18mk73-009\", \"type\":\"bank\", \"amount\":\"150\", \"currency\":\"EUR\"}";
+    }
+}

core-java-modules/core-java-16/src/main/java/com/baeldung/value_based_class/Point.java

@@ -30,6 +30,11 @@ public final class Point {
         return new Point(x, y, z);
     }
 
+    @Override
+    public String toString() {
+        return "Point{" + "x=" + x + ", y=" + y + ", z=" + z + '}';
+    }
+
     @Override
     public boolean equals(Object other) {
         if (other == null || getClass() != other.getClass())

core-java-modules/core-java-16/src/test/java/com/baeldung/value_based_class/ValueBasedClassUnitTest.java

@@ -1,14 +1,17 @@
 package com.baeldung.value_based_class;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.junit.Assert;
 import org.junit.Test;
 
 public class ValueBasedClassUnitTest {
     @Test
     public void givenAutoboxedAndPrimitive_whenCompared_thenReturnEquals() {
-        int primitive_a = 125;
-        Integer obj_a = 125; // this is autoboxed
-        Assert.assertSame(primitive_a, obj_a);
+        List<Integer> list = new ArrayList<>();
+        list.add(1); // this is autoboxed
+        Assert.assertEquals(list.get(0), Integer.valueOf(1));
     }
 
     @Test

core-java-modules/core-java-18/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-18</artifactId>
+    <name>core-java-18</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../../</relativePath>
+    </parent>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <release>${maven.compiler.release}</release>
+                    <compilerArgs>--enable-preview</compilerArgs>
+                    <source>${maven.compiler.source.version}</source>
+                    <target>${maven.compiler.target.version}</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${surefire.plugin.version}</version>
+                <configuration>
+                    <forkCount>1</forkCount>
+                </configuration>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.apache.maven.surefire</groupId>
+                        <artifactId>surefire-api</artifactId>
+                        <version>${surefire.plugin.version}</version>
+                    </dependency>
+                </dependencies>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <maven.compiler.source.version>18</maven.compiler.source.version>
+        <maven.compiler.target.version>18</maven.compiler.target.version>
+        <maven.compiler.release>18</maven.compiler.release>
+        <surefire.plugin.version>3.0.0-M5</surefire.plugin.version>
+    </properties>
+
+</project>

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/FinalizationExamples.java

@@ -0,0 +1,27 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+
+public class FinalizationExamples {
+    FileInputStream fis = null;
+
+    public void readFileOperationWithFinalization() throws IOException {
+        try {
+            fis = new FileInputStream("input.txt");
+            // perform operation on the file
+            System.out.println(fis.readAllBytes().length);
+
+        } finally {
+            if (fis != null)
+                fis.close();
+        }
+    }
+
+    public void readFileOperationWithTryWith() throws IOException {
+        try (FileInputStream fis = new FileInputStream("input.txt")) {
+            // perform operations
+            System.out.println(fis.readAllBytes().length);
+        }
+    }
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/MyCleanerResourceClass.java

@@ -0,0 +1,48 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.lang.ref.Cleaner;
+
+public class MyCleanerResourceClass implements AutoCloseable {
+    private static Resource resource;
+
+    private static final Cleaner cleaner = Cleaner.create();
+    private final Cleaner.Cleanable cleanable;
+
+    public MyCleanerResourceClass() {
+        resource = new Resource();
+        this.cleanable = cleaner.register(this, new CleaningState());
+    }
+
+    public void useResource() {
+        // using the resource here
+        resource.use();
+    }
+
+    @Override
+    public void close() {
+        // perform actions to close all underlying resources
+        this.cleanable.clean();
+    }
+
+    static class CleaningState implements Runnable {
+        CleaningState() {
+            // constructor
+        }
+
+        @Override
+        public void run() {
+            // some cleanup action
+            System.out.println("Cleanup done");
+        }
+    }
+
+    static class Resource {
+        void use() {
+            System.out.println("Using the resource");
+        }
+
+        void close() {
+            System.out.println("Cleanup done");
+        }
+    }
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/MyCloseableResourceClass.java

@@ -0,0 +1,25 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+public class MyCloseableResourceClass implements AutoCloseable {
+
+    private final FileInputStream fis;
+
+    public MyCloseableResourceClass() throws FileNotFoundException {
+        this.fis = new FileInputStream("src/main/resources/file.txt");
+
+    }
+
+    public int getByteLength() throws IOException {
+        System.out.println("Some operation");
+        return this.fis.readAllBytes().length;
+    }
+    @Override
+    public void close() throws IOException {
+        System.out.println("Finalized object");
+        this.fis.close();
+    }
+}

core-java-modules/core-java-18/src/main/java/com/baeldung/finalization_closeable_cleaner/MyFinalizableResourceClass.java

@@ -0,0 +1,24 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+public class MyFinalizableResourceClass {
+    private FileInputStream fis;
+
+    public MyFinalizableResourceClass() throws FileNotFoundException {
+        this.fis = new FileInputStream("src/main/resources/file.txt");
+    }
+
+    public int getByteLength() throws IOException {
+        System.out.println("Some operation");
+        return this.fis.readAllBytes().length;
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        System.out.println("Finalized object");
+        this.fis.close();
+    }
+}

core-java-modules/core-java-18/src/main/resources/file.txt

@@ -0,0 +1 @@
+This is a test file.

core-java-modules/core-java-18/src/test/java/com/baeldung/finalization_closeable_cleaner/FinalizationCloseableCleanerUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.finalization_closeable_cleaner;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import java.io.IOException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FinalizationCloseableCleanerUnitTest {
+
+    @Test
+    public void givenMyFinalizationResource_whenUsingFinalize_thenShouldClean() {
+        assertDoesNotThrow(() -> {
+            MyFinalizableResourceClass mfr = new MyFinalizableResourceClass();
+            mfr.getByteLength();
+        });
+    }
+    @Test
+    public void givenMyCleanerResource_whenUsingCleanerAPI_thenShouldClean() {
+        assertDoesNotThrow(() -> {
+            try (MyCleanerResourceClass myCleanerResourceClass = new MyCleanerResourceClass()) {
+                myCleanerResourceClass.useResource();
+            }
+        });
+    }
+
+    @Test
+    public void givenCloseableResource_whenUsingTryWith_thenShouldClose() throws IOException {
+        int length = 0;
+        try (MyCloseableResourceClass mcr = new MyCloseableResourceClass()) {
+            length = mcr.getByteLength();
+        }
+        Assert.assertEquals(20, length);
+    }
+}

core-java-modules/core-java-21/README.md

@@ -1,3 +1,5 @@
 ## Relevant Articles
 - [Sequenced Collections in Java 21](https://www.baeldung.com/java-21-sequenced-collections)
 - [String Templates in Java 21](https://www.baeldung.com/java-21-string-templates)
+- [Unnamed Classes and Instance Main Methods in Java 21](https://www.baeldung.com/java-21-unnamed-class-instance-main)
+- [Unnamed Patterns and Variables in Java 21](https://www.baeldung.com/java-unnamed-patterns-variables)

core-java-modules/core-java-arrays-convert/src/main/java/com/baeldung/array/conversions/CharArrayToIntArrayUtils.java

@@ -0,0 +1,67 @@
+package com.baeldung.array.conversions;
+
+import java.util.Arrays;
+
+public class CharArrayToIntArrayUtils {
+
+    static int[] usingGetNumericValueMethod(char[] chars) {
+        if (chars == null) {
+            return null;
+        }
+
+        int[] ints = new int[chars.length];
+        for (int i = 0; i < chars.length; i++) {
+            ints[i] = Character.getNumericValue(chars[i]);
+        }
+
+        return ints;
+    }
+
+    static int[] usingDigitMethod(char[] chars) {
+        if (chars == null) {
+            return null;
+        }
+
+        int[] ints = new int[chars.length];
+        for (int i = 0; i < chars.length; i++) {
+            ints[i] = Character.digit(chars[i], 10);
+        }
+
+        return ints;
+    }
+
+    static int[] usingStreamApiMethod(char[] chars) {
+        if (chars == null) {
+            return null;
+        }
+
+        return new String(chars).chars()
+          .map(c -> c - 48)
+          .toArray();
+    }
+
+    static int[] usingParseIntMethod(char[] chars) {
+        if (chars == null) {
+            return null;
+        }
+
+        int[] ints = new int[chars.length];
+        for (int i = 0; i < chars.length; i++) {
+            ints[i] = Integer.parseInt(String.valueOf(chars[i]));
+        }
+
+        return ints;
+    }
+
+    static int[] usingArraysSetAllMethod(char[] chars) {
+        if (chars == null) {
+            return null;
+        }
+
+        int[] ints = new int[chars.length];
+        Arrays.setAll(ints, i -> Character.getNumericValue(chars[i]));
+
+        return ints;
+    }
+
+}

core-java-modules/core-java-arrays-convert/src/test/java/com/baeldung/array/conversions/CharArrayToIntArrayUtilsUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.array.conversions;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+class CharArrayToIntArrayUtilsUnitTest {
+
+    @Test
+    void givenCharArray_whenUsingGetNumericValueMethod_shouldGetIntArray() {
+        int[] expected = { 2, 3, 4, 5 };
+        char[] chars = { '2', '3', '4', '5' };
+        int[] result = CharArrayToIntArrayUtils.usingGetNumericValueMethod(chars);
+
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void givenCharArray_whenUsingDigitMethod_shouldGetIntArray() {
+        int[] expected = { 1, 2, 3, 6 };
+        char[] chars = { '1', '2', '3', '6' };
+        int[] result = CharArrayToIntArrayUtils.usingDigitMethod(chars);
+
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void givenCharArray_whenUsingStreamApi_shouldGetIntArray() {
+        int[] expected = { 9, 8, 7, 6 };
+        char[] chars = { '9', '8', '7', '6' };
+        int[] result = CharArrayToIntArrayUtils.usingStreamApiMethod(chars);
+
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void givenCharArray_whenUsingParseIntMethod_shouldGetIntArray() {
+        int[] expected = { 9, 8, 7, 6 };
+        char[] chars = { '9', '8', '7', '6' };
+        int[] result = CharArrayToIntArrayUtils.usingParseIntMethod(chars);
+
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void givenCharArray_whenUsingArraysSetAllMethod_shouldGetIntArray() {
+        int[] expected = { 4, 9, 2, 3 };
+        char[] chars = { '4', '9', '2', '3' };
+        int[] result = CharArrayToIntArrayUtils.usingArraysSetAllMethod(chars);
+
+        assertArrayEquals(expected, result);
+    }
+
+}

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

@@ -5,3 +5,4 @@ This module contains articles about Java Character Class
 ### Relevant Articles: 
 - [Character#isAlphabetic vs. Character#isLetter](https://www.baeldung.com/java-character-isletter-isalphabetic)
 - [Difference Between Java’s “char” and “String”](https://www.baeldung.com/java-char-vs-string)
+- [Increment Character in Java](https://www.baeldung.com/java-char-sequence)

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

@@ -5,4 +5,6 @@
 ### Relevant Articles:
 - [Introduction to Roaring Bitmap](https://www.baeldung.com/java-roaring-bitmap-intro)
 - [Creating Custom Iterator in Java](https://www.baeldung.com/java-creating-custom-iterator)
+- [Difference Between Arrays.sort() and Collections.sort()](https://www.baeldung.com/java-arrays-collections-sort-methods)
+- [Skipping the First Iteration in Java](https://www.baeldung.com/java-skip-first-iteration)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-4)

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

@@ -3,4 +3,4 @@
 This module contains articles about the Java ArrayList collection
 
 ### Relevant Articles:
-- [Create an ArrayList with Multiple Object Types](https://www.baeldung.com/arraylist-with-multiple-object-types)
+- [Create an ArrayList with Multiple Object Types](https://www.baeldung.com/java-arraylist-multiple-object-types)

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

@@ -3,3 +3,4 @@
 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)

core-java-modules/core-java-collections-maps-7/README.md

@@ -0,0 +1 @@
+## Relevant Articles

core-java-modules/core-java-collections-maps-7/pom.xml

@@ -0,0 +1,78 @@
+<?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-7</artifactId>
+    <name>core-java-collections-maps-7</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <artifactId>core-java-modules</artifactId>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <properties>
+        <spring.version>5.2.5.RELEASE</spring.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>2.12.4</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>1.36</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>2.8.9</version>
+        </dependency>
+        <dependency>
+            <groupId>org.json</groupId>
+            <artifactId>json</artifactId>
+            <version>20230227</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

core-java-modules/core-java-collections-maps-7/src/main/java/com/baeldung/map/ConvertHashMapStringToHashMapObjectUsingtoString.java

@@ -0,0 +1,60 @@
+package com.baeldung.map;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ConvertHashMapStringToHashMapObjectUsingtoString {
+    public String name;
+    public int age;
+
+    public ConvertHashMapStringToHashMapObjectUsingtoString(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public static ConvertHashMapStringToHashMapObjectUsingtoString deserializeCustomObject(String valueString) {
+        if (valueString.startsWith("{") && valueString.endsWith("}")) {
+            valueString = valueString.substring(1, valueString.length() - 1);
+            String[] parts = valueString.split(",");
+            String name = null;
+            int age = -1;
+            for (String part : parts) {
+                String[] keyValue = part.split("=");
+                if (keyValue.length == 2) {
+                    String key = keyValue[0].trim();
+                    String val = keyValue[1].trim();
+                    if (key.equals("name")) {
+                        name = val;
+                    } else if (key.equals("age")) {
+                        age = Integer.parseInt(val);
+                    }
+                }
+            }
+            if (name != null && age >= 0) {
+                return new ConvertHashMapStringToHashMapObjectUsingtoString(name, age);
+            }
+        }
+        return new ConvertHashMapStringToHashMapObjectUsingtoString("", -1);
+    }
+
+    public static void main(String[] args) {
+        String hashMapString = "{key1={name=John, age=30}, key2={name=Alice, age=25}}";
+        String keyValuePairs = hashMapString.replaceAll("[{}\\s]", "");
+        String[] pairs = keyValuePairs.split(",");
+        Map<String, ConvertHashMapStringToHashMapObjectUsingtoString> actualHashMap = new HashMap<>();
+        for (String pair : pairs) {
+            String[] keyValue = pair.split("=");
+            if (keyValue.length == 2) {
+                String key = keyValue[0];
+                ConvertHashMapStringToHashMapObjectUsingtoString value = deserializeCustomObject(keyValue[1]);
+                actualHashMap.put(key, value);
+            }
+        }
+        System.out.println(actualHashMap);
+    }
+
+    @Override
+    public String toString() {
+        return "{name=" + name + ", age=" + age + "}";
+    }
+}

core-java-modules/core-java-collections-maps-7/src/test/java/com/baeldung/map/ConvertHashMapStringToHashMapObjectUsingtoStringUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.map;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class ConvertHashMapStringToHashMapObjectUsingtoStringUnitTest {
+
+    @Test
+    void givenValidCustomObject_whenSerializing_thenSerializedStringIsCorrect() {
+        ConvertHashMapStringToHashMapObjectUsingtoString customObject = new ConvertHashMapStringToHashMapObjectUsingtoString("John", 30);
+        String expectedSerializedString = "{name=John, age=30}";
+        assertEquals(expectedSerializedString, customObject.toString());
+    }
+
+    @Test
+    void givenValidSerializedString_whenDeserializing_thenCustomObjectIsCorrect() {
+        String serializedString = "{name=Alice, age=25}";
+        ConvertHashMapStringToHashMapObjectUsingtoString customObject = ConvertHashMapStringToHashMapObjectUsingtoString.deserializeCustomObject(serializedString);
+        assertEquals("Alice", customObject.name);
+        assertEquals(25, customObject.age);
+    }
+
+    @Test
+    void givenInvalidSerializedString_whenDeserializing_thenDefaultCustomObjectIsCreated() {
+        String invalidSerializedString = "{invalidString}";
+        ConvertHashMapStringToHashMapObjectUsingtoString customObject = ConvertHashMapStringToHashMapObjectUsingtoString.deserializeCustomObject(invalidSerializedString);
+        assertEquals("", customObject.name);
+        assertEquals(-1, customObject.age);
+    }
+}

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

@@ -12,10 +12,10 @@ public class EpochTimeToLocalDateTimeConverterUnitTest {
     @Test
     public void testConvertEpochTimeToLocalDateTime() {
         long epochTimeMillis = 1624962431000L; // Example epoch time in milliseconds
-        LocalDateTime expectedDateTime = LocalDateTime.of(2021, 6, 29, 12, 13, 51);
+        LocalDateTime expectedDateTime = LocalDateTime.of(2021, 6, 29, 10, 27, 11);
 
         Instant instant = Instant.ofEpochMilli(epochTimeMillis);
-        ZoneId zoneId = ZoneId.systemDefault();
+        ZoneId zoneId = ZoneId.of("UTC");
         LocalDateTime actualDateTime = instant.atZone(zoneId).toLocalDateTime();
 
         assertEquals(expectedDateTime, actualDateTime);

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

@@ -3,6 +3,6 @@
 This module contains articles about core Java input and output (IO)
 
 ### Relevant Articles: 
-
+- [Get File Extension From MIME Type in Java](https://www.baeldung.com/java-mime-type-file-extension)
 - [[<-- Prev]](/core-java-modules/core-java-io-4)
 

core-java-modules/core-java-io-5/src/test/java/com/baeldung/rmlinebreaks/RemoveLinebreaksUnitTest.java

@@ -0,0 +1,72 @@
+package com.baeldung.rmlinebreaks;
+
+import org.junit.jupiter.api.Test;
+
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+public class RemoveLinebreaksUnitTest {
+
+    private Path file1Path() throws Exception {
+        return Paths.get(this.getClass().getClassLoader().getResource("multiple-line-1.txt").toURI());
+    }
+
+    private Path file2Path() throws Exception {
+        return Paths.get(this.getClass().getClassLoader().getResource("multiple-line-2.txt").toURI());
+    }
+
+    @Test
+    void whenRemovingLineSeparatorFromFile1_thenGetTheExpectedResult() throws Exception {
+        String content = Files.readString(file1Path(), StandardCharsets.UTF_8);
+
+        String result = content.replace(System.getProperty("line.separator"), "");
+        assertEquals("A, B, C, D, E, F", result);
+    }
+
+    @Test
+    void whenRemovingLineSeparatorFromFile2_thenNotGetTheExpectedResult() throws Exception {
+        String content = Files.readString(file2Path(), StandardCharsets.UTF_8);
+
+        String result = content.replace(System.getProperty("line.separator"), "");
+        assertNotEquals("A, B, C, D, E, F", result); // <-- NOT equals assertion!
+    }
+
+    @Test
+    void whenRemovingAllLinebreaks_thenGetTheExpectedResult() throws Exception {
+        String content1 = Files.readString(file1Path(), StandardCharsets.UTF_8);
+
+        // file contains CRLF
+        String content2 = Files.readString(file2Path(), StandardCharsets.UTF_8);
+
+        String result1 = content1.replace("\r", "").replace("\n", "");
+        String result2 = content2.replace("\r", "").replace("\n", "");
+
+        assertEquals("A, B, C, D, E, F", result1);
+        assertEquals("A, B, C, D, E, F", result2);
+
+        String resultReplaceAll = content2.replaceAll("[\\n\\r]", "");
+        assertEquals("A, B, C, D, E, F", resultReplaceAll);
+
+    }
+
+    @Test
+    void whenUsingReadAllLinesAndJoin_thenGetExpectedResult() throws Exception {
+        List<String> lines1 = Files.readAllLines(file1Path(), StandardCharsets.UTF_8);
+
+        // file contains CRLF
+        List<String> lines2 = Files.readAllLines(file2Path(), StandardCharsets.UTF_8);
+
+        String result1 = String.join("", lines1);
+        String result2 = String.join("", lines2);
+
+        assertEquals("A, B, C, D, E, F", result1);
+        assertEquals("A, B, C, D, E, F", result2);
+    }
+
+}

core-java-modules/core-java-io-5/src/test/resources/multiple-line-1.txt

@@ -0,0 +1,6 @@
+A,
+ B,
+ C,
+ D,
+ E,
+ F

core-java-modules/core-java-io-5/src/test/resources/multiple-line-2.txt

@@ -0,0 +1,4 @@
+A,
 B,
+ C,
+ D,
 E,
+ F