Merge branch 'master' into JAVA-5223

core-java-modules/core-java-11-2/pom.xml

@@ -50,6 +50,11 @@
             <version>${junit.jupiter.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -73,6 +78,7 @@
         <junit.jupiter.version>5.7.0</junit.jupiter.version>
         <assertj.version>3.17.2</assertj.version>
         <mockserver.version>5.11.1</mockserver.version>
+        <commons-lang3.version>3.12.0</commons-lang3.version>
     </properties>
 
 </project>

core-java-modules/core-java-11-2/src/test/java/com/baeldung/version/VersionUnitTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.version;
+
+import org.apache.commons.lang3.SystemUtils;
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+public class VersionUnitTest {
+
+    @Test
+    public void givenJava_whenUsingRuntime_thenGetVersion() {
+        String expectedVersion = "11";
+        Runtime.Version runtimeVersion = Runtime.version();
+        String version = String.valueOf(runtimeVersion.version().get(0));
+        Assertions.assertThat(version).isEqualTo(expectedVersion);
+    }
+
+    @Test
+    @Disabled("Only valid for Java 8 and lower")
+    public void givenJava_whenUsingCommonsLang_thenGetVersion() {
+        int expectedVersion = 8;
+        String[] versionElements = SystemUtils.JAVA_SPECIFICATION_VERSION.split("\\.");
+        int discard = Integer.parseInt(versionElements[0]);
+        int version;
+        if (discard == 1) {
+            version = Integer.parseInt(versionElements[1]);
+        } else {
+            version = discard;
+        }
+        Assertions.assertThat(version).isEqualTo(expectedVersion);
+    }
+
+    @Test
+    @Disabled("Only valid for Java 8 and lower")
+    public void givenJava_whenUsingSystemProp_thenGetVersion() {
+        int expectedVersion = 8;
+        String[] versionElements = System.getProperty("java.version").split("\\.");
+        int discard = Integer.parseInt(versionElements[0]);
+        int version;
+        if (discard == 1) {
+            version = Integer.parseInt(versionElements[1]);
+        } else {
+            version = discard;
+        }
+        Assertions.assertThat(version).isEqualTo(expectedVersion);
+    }
+}
+

core-java-modules/core-java-jpms/decoupling-pattern2/consumermodule2/pom.xml

@@ -45,4 +45,4 @@
         <providermodule.version>1.0</providermodule.version>
     </properties>
 
-</project>
+</project>

core-java-modules/core-java-lang-4/src/main/java/com/baeldung/hash/Player.java

@@ -0,0 +1,91 @@
+package com.baeldung.hash;
+
+import java.util.Objects;
+
+public class Player {
+    private String firstName;
+    private String lastName;
+    private String position;
+
+    public Player() {
+
+    }
+
+    public Player(String firstName, String lastName, String position) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.position = position;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getPosition() {
+        return position;
+    }
+
+    public void setPosition(String position) {
+        this.position = position;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(firstName, lastName, position);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj == null) {
+            return false;
+        }
+
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+
+        Player other = (Player) obj;
+
+        if (firstName == null) {
+            if (other.firstName != null) {
+                return false;
+            }
+        } else if (!firstName.equals(other.firstName)) {
+            return false;
+        }
+
+        if (lastName == null) {
+            if (other.lastName != null) {
+                return false;
+            }
+        } else if (!lastName.equals(other.lastName)) {
+            return false;
+        }
+
+        if (position == null) {
+            if (other.position != null) {
+                return false;
+            }
+        } else if (!position.equals(other.position)) {
+            return false;
+        }
+        return true;
+    }
+
+}

core-java-modules/core-java-lang-4/src/test/java/com/baeldung/hash/HashCodeUnitTest.java

@@ -0,0 +1,67 @@
+package com.baeldung.hash;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+import java.util.Objects;
+
+import org.junit.Test;
+
+public class HashCodeUnitTest {
+
+    @Test
+    public void whenCallingObjectsHashCodeOnIndenticalObjects_thenSameHashCodeReturned() {
+        String stringOne = "test";
+        String stringTwo = "test";
+        int hashCode1 = Objects.hashCode(stringOne);
+        int hashCode2 = Objects.hashCode(stringTwo);
+
+        assertEquals(hashCode1, hashCode2);
+    }
+
+    @Test
+    public void whenCallingObjectsHashCodeOnNullObject_thenZeroReturned() {
+        String nullString = null;
+        int hashCode = Objects.hashCode(nullString);
+        assertEquals(0, hashCode);
+    }
+
+    @Test
+    public void whenCallingObjectHashCodeOnIndenticalObjects_thenSameHashCodeReturned() {
+        Double valueOne = Double.valueOf(1.0012);
+        Double valueTwo = Double.valueOf(1.0012);
+
+        int hashCode1 = valueOne.hashCode();
+        int hashCode2 = valueTwo.hashCode();
+
+        assertEquals(hashCode1, hashCode2);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void whenCallingObjectHashCodeOnNullObject_theNullPointerExceptionThrown() {
+        Double value = null;
+        value.hashCode();
+    }
+
+    @Test
+    public void whenCallingObjectsHashOnStrings_thenSameHashCodeReturned() {
+        String strOne = "one";
+        String strTwo = "two";
+        String strOne2 = "one";
+        String strTwo2 = "two";
+
+        int hashCode1 = Objects.hash(strOne, strTwo);
+        int hashCode2 = Objects.hash(strOne2, strTwo2);
+
+        assertEquals(hashCode1, hashCode2);
+    }
+
+    @Test
+    public void whenCallingObjectsHashOnSingleString_thenDifferentHashcodeFromObjectsHashCodeCallReturned() {
+        String testString = "test string";
+        int hashCode1 = Objects.hash(testString);
+        int hashCode2 = Objects.hashCode(testString);
+
+        assertNotEquals(hashCode1, hashCode2);
+    }
+}

core-java-modules/core-java-lang-4/src/test/java/com/baeldung/hash/PlayerUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.hash;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+
+public class PlayerUnitTest {
+
+    @Test
+    public void whenCallingHashCodeOnIdenticalValue_thenSameHashCodeReturned() {
+        Player player = new Player("Eduardo", "Rodriguez", "Pitcher");
+        Player indenticalPlayer = new Player("Eduardo", "Rodriguez", "Pitcher");
+
+        int hashCode1 = player.hashCode();
+        int hashCode2 = player.hashCode();
+        int hashCode3 = indenticalPlayer.hashCode();
+
+        assertEquals(hashCode1, hashCode2);
+        assertEquals(hashCode1, hashCode3);
+    }
+
+    @Test
+    public void whenCallingHashCodeAndArraysHashCode_thenSameHashCodeReturned() {
+        Player player = new Player("Bobby", "Dalbec", "First Base");
+        int hashcode1 = player.hashCode();
+        String[] playerInfo = { "Bobby", "Dalbec", "First Base" };
+        int hashcode2 = Arrays.hashCode(playerInfo);
+
+        assertEquals(hashcode1, hashcode2);
+    }
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacevsabstractclass/Car.java

@@ -0,0 +1,42 @@
+package com.baeldung.interfacevsabstractclass;
+
+public class Car extends Vehicle {
+
+    public Car(String vechicleName) {
+        super(vechicleName);
+    }
+
+    public Car(String vechicleName, String vehicleModel) {
+        super(vechicleName, vehicleModel);
+    }
+
+    public Car(String vechicleName, String vehicleModel, Long makeYear) {
+        super(vechicleName, vehicleModel, makeYear);
+    }
+
+    @Override
+    protected void start() {
+        // code implementation details on starting a car.
+    }
+
+    @Override
+    protected void stop() {
+        // code implementation details on stopping a car.
+    }
+
+    @Override
+    protected void drive() {
+        // code implementation details on start driving a car.
+    }
+
+    @Override
+    protected void changeGear() {
+        // code implementation details on changing the car gear.
+    }
+
+    @Override
+    protected void reverse() {
+        // code implementation details on reverse driving a car.
+    }
+
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacevsabstractclass/ImageSender.java

@@ -0,0 +1,12 @@
+package com.baeldung.interfacevsabstractclass;
+
+import java.io.File;
+
+public class ImageSender implements Sender {
+
+    @Override
+    public void send(File fileToBeSent) {
+        // image sending implementation code.
+    }
+
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacevsabstractclass/Sender.java

@@ -0,0 +1,8 @@
+package com.baeldung.interfacevsabstractclass;
+
+import java.io.File;
+
+public interface Sender {
+
+    void send(File fileToBeSent);
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacevsabstractclass/Vehicle.java

@@ -0,0 +1,57 @@
+package com.baeldung.interfacevsabstractclass;
+
+public abstract class Vehicle {
+
+    private String vehicleName;
+    private String vehicleModel;
+    private Long makeYear;
+
+    public Vehicle(String vehicleName) {
+        this.vehicleName = vehicleName;
+    }
+
+    public Vehicle(String vehicleName, String vehicleModel) {
+        this(vehicleName);
+        this.vehicleModel = vehicleModel;
+    }
+
+    public Vehicle(String vechicleName, String vehicleModel, Long makeYear) {
+        this(vechicleName, vehicleModel);
+        this.makeYear = makeYear;
+    }
+
+    public String getVehicleName() {
+        return vehicleName;
+    }
+
+    public void setVehicleName(String vehicleName) {
+        this.vehicleName = vehicleName;
+    }
+
+    public String getVehicleModel() {
+        return vehicleModel;
+    }
+
+    public void setVehicleModel(String vehicleModel) {
+        this.vehicleModel = vehicleModel;
+    }
+
+    public Long getMakeYear() {
+        return makeYear;
+    }
+
+    public void setMakeYear(Long makeYear) {
+        this.makeYear = makeYear;
+    }
+
+    protected abstract void start();
+
+    protected abstract void stop();
+
+    protected abstract void drive();
+
+    protected abstract void changeGear();
+
+    protected abstract void reverse();
+
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/interfacevsabstractclass/VideoSender.java

@@ -0,0 +1,12 @@
+package com.baeldung.interfacevsabstractclass;
+
+import java.io.File;
+
+public class VideoSender implements Sender {
+
+    @Override
+    public void send(File fileToBeSent) {
+        // video sending implementation code
+    }
+
+}

core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interfacevsabstractclass/SenderUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.interfacevsabstractclass;
+
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.interfacevsabstractclass.ImageSender;
+import com.baeldung.interfacevsabstractclass.Sender;
+
+import java.io.File;
+
+class SenderUnitTest {
+
+    public final static String IMAGE_FILE_PATH = "/sample_image_file_path/photo.jpg";
+
+    @Test
+    void givenImageUploaded_whenButtonClicked_thenSendImage() {
+        File imageFile = new File(IMAGE_FILE_PATH);
+
+        Sender sender = new ImageSender();
+        sender.send(imageFile);
+    }
+
+}

core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/interfacevsabstractclass/VehicleUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.interfacevsabstractclass;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.interfacevsabstractclass.Car;
+import com.baeldung.interfacevsabstractclass.Vehicle;
+
+class VehicleUnitTest {
+
+    @Test
+    void givenVehicle_whenNeedToDrive_thenStart() {
+        Vehicle car = new Car("BMW");
+
+        car.start();
+        car.drive();
+        car.changeGear();
+        car.stop();
+    }
+
+}

core-java-modules/core-java-networking-2/src/test/java/com/baeldung/download/FileDownloadIntegrationTest.java

@@ -17,9 +17,9 @@ import static org.junit.Assert.assertTrue;
 
 public class FileDownloadIntegrationTest {
     
-    static String FILE_URL = "http://ovh.net/files/1Mio.dat";
+    static String FILE_URL = "https://s3.amazonaws.com/baeldung.com/Do+JSON+with+Jackson+by+Baeldung.pdf";
     static String FILE_NAME = "file.dat";
-    static String FILE_MD5_HASH = "6cb91af4ed4c60c11613b75cd1fc6116";
+    static String FILE_MD5_HASH = "c959feb066b37f5c4f0e0f45bbbb4f86";
     
     @Test
     public void givenJavaIO_whenDownloadingFile_thenDownloadShouldBeCorrect() throws NoSuchAlgorithmException, IOException {

core-java-modules/core-java-streams-3/pom.xml

@@ -27,6 +27,17 @@
             <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh.version}</version>
+            <scope>test</scope>
+        </dependency>
         <!-- test scoped -->
         <dependency>
             <groupId>org.assertj</groupId>
@@ -44,11 +55,30 @@
                 <filtering>true</filtering>
             </resource>
         </resources>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                    <annotationProcessorPaths>
+                        <path>
+                            <groupId>org.openjdk.jmh</groupId>
+                            <artifactId>jmh-generator-annprocess</artifactId>
+                            <version>${jmh.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
+                </configuration>
+            </plugin>
+        </plugins>
     </build>
 
     <properties>
+        <lombok.version>1.18.20</lombok.version>
         <!-- testing -->
         <assertj.version>3.6.1</assertj.version>
+        <jmh.version>1.29</jmh.version>
     </properties>
 
 </project>

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/parallel/BenchmarkRunner.java

@@ -0,0 +1,9 @@
+package com.baeldung.streams.parallel;
+
+public class BenchmarkRunner {
+
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+
+}

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/parallel/DifferentSourceSplitting.java

@@ -0,0 +1,54 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+public class DifferentSourceSplitting {
+
+    private static final List<Integer> arrayListOfNumbers = new ArrayList<>();
+    private static final List<Integer> linkedListOfNumbers = new LinkedList<>();
+
+    static {
+        IntStream.rangeClosed(1, 1_000_000).forEach(i -> {
+            arrayListOfNumbers.add(i);
+            linkedListOfNumbers.add(i);
+        });
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceArrayListSequential() {
+        arrayListOfNumbers.stream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceArrayListParallel() {
+        arrayListOfNumbers.parallelStream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceLinkedListSequential() {
+        linkedListOfNumbers.stream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void differentSourceLinkedListParallel() {
+        linkedListOfNumbers.parallelStream().reduce(0, Integer::sum);
+    }
+
+}

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/parallel/MemoryLocalityCosts.java

@@ -0,0 +1,52 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.Arrays;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+public class MemoryLocalityCosts {
+
+    private static final int[] intArray = new int[1_000_000];
+    private static final Integer[] integerArray = new Integer[1_000_000];
+
+    static {
+        IntStream.rangeClosed(1, 1_000_000).forEach(i -> {
+            intArray[i-1] = i;
+            integerArray[i-1] = i;
+        });
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntArraySequential() {
+        Arrays.stream(intArray).reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntArrayParallel() {
+        Arrays.stream(intArray).parallel().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntegerArraySequential() {
+        Arrays.stream(integerArray).reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void localityIntegerArrayParallel() {
+        Arrays.stream(integerArray).parallel().reduce(0, Integer::sum);
+    }
+
+}

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/parallel/MergingCosts.java

@@ -0,0 +1,52 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class MergingCosts {
+
+    private static final List<Integer> arrayListOfNumbers = new ArrayList<>();
+
+    static {
+        IntStream.rangeClosed(1, 1_000_000).forEach(i -> {
+            arrayListOfNumbers.add(i);
+        });
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsSumSequential() {
+        arrayListOfNumbers.stream().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsSumParallel() {
+        arrayListOfNumbers.stream().parallel().reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsGroupingSequential() {
+        arrayListOfNumbers.stream().collect(Collectors.toSet());
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void mergingCostsGroupingParallel() {
+        arrayListOfNumbers.stream().parallel().collect(Collectors.toSet());
+    }
+
+}

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/parallel/ParallelStream.java

@@ -0,0 +1,15 @@
+package com.baeldung.streams.parallel;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class ParallelStream {
+
+    public static void main(String[] args) {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        listOfNumbers.parallelStream().forEach(number ->
+          System.out.println(number + " " + Thread.currentThread().getName())
+        );
+    }
+
+}

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/parallel/SequentialStream.java

@@ -0,0 +1,15 @@
+package com.baeldung.streams.parallel;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class SequentialStream {
+
+    public static void main(String[] args) {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        listOfNumbers.stream().forEach(number ->
+          System.out.println(number + " " + Thread.currentThread().getName())
+        );
+    }
+
+}

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/parallel/SplittingCosts.java

@@ -0,0 +1,27 @@
+package com.baeldung.streams.parallel;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+public class SplittingCosts {
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void sourceSplittingIntStreamSequential() {
+        IntStream.rangeClosed(1, 100).reduce(0, Integer::sum);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.AverageTime)
+    @OutputTimeUnit(TimeUnit.NANOSECONDS)
+    public static void sourceSplittingIntStreamParallel() {
+        IntStream.rangeClosed(1, 100).parallel().reduce(0, Integer::sum);
+    }
+
+}

core-java-modules/core-java-streams-3/src/test/java/com/baeldung/streams/parallel/ForkJoinUnitTest.java

@@ -0,0 +1,46 @@
+package com.baeldung.streams.parallel;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ForkJoinPool;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ForkJoinUnitTest {
+
+    @Test
+    void givenSequentialStreamOfNumbers_whenReducingSumWithIdentityFive_thenResultIsCorrect() {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        int sum = listOfNumbers.stream().reduce(5, Integer::sum);
+        assertThat(sum).isEqualTo(15);
+    }
+
+    @Test
+    void givenParallelStreamOfNumbers_whenReducingSumWithIdentityFive_thenResultIsNotCorrect() {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        int sum = listOfNumbers.parallelStream().reduce(5, Integer::sum);
+        assertThat(sum).isNotEqualTo(15);
+    }
+
+    @Test
+    void givenParallelStreamOfNumbers_whenReducingSumWithIdentityZero_thenResultIsCorrect() {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        int sum = listOfNumbers.parallelStream().reduce(0, Integer::sum) + 5;
+        assertThat(sum).isEqualTo(15);
+    }
+
+    @Test
+    public void givenParallelStreamOfNumbers_whenUsingCustomThreadPool_thenResultIsCorrect()
+      throws InterruptedException, ExecutionException {
+        List<Integer> listOfNumbers = Arrays.asList(1, 2, 3, 4);
+        ForkJoinPool customThreadPool = new ForkJoinPool(4);
+        int sum = customThreadPool.submit(
+          () -> listOfNumbers.parallelStream().reduce(0, Integer::sum)).get();
+        customThreadPool.shutdown();
+        assertThat(sum).isEqualTo(10);
+    }
+
+}

core-java-modules/core-java-string-operations-3/src/test/java/com/baeldung/splitkeepdelimiters/SplitAndKeepDelimitersUnitTest.java

@@ -0,0 +1,59 @@
+package com.baeldung.splitkeepdelimiters;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.regex.Pattern;
+
+import org.apache.commons.lang3.StringUtils;
+import org.junit.jupiter.api.Test;
+
+import com.google.common.base.Splitter;
+
+public class SplitAndKeepDelimitersUnitTest {
+
+    private final String positivelookAheadRegex = "((?=@))";
+    private final String positivelookBehindRegex = "((?<=@))";
+    private final String positivelookAroundRegex = "((?=@)|(?<=@))";
+    private final String positiveLookAroundMultiDelimiterRegex = "((?=:|#|@)|(?<=:|#|@))";
+
+    private String text = "Hello@World@This@Is@A@Java@Program";
+    private String textMixed = "@HelloWorld@This:Is@A#Java#Program";
+    private String textMixed2 = "pg@no;10@hello;world@this;is@a#10words;Java#Program";
+
+    @Test
+    public void givenString_splitAndKeepDelimiters_using_javaLangString() {
+
+        assertThat(text.split(positivelookAheadRegex)).containsExactly("Hello", "@World", "@This", "@Is", "@A", "@Java", "@Program");
+
+        assertThat(text.split(positivelookBehindRegex)).containsExactly("Hello@", "World@", "This@", "Is@", "A@", "Java@", "Program");
+
+        assertThat(text.split(positivelookAroundRegex)).containsExactly("Hello", "@", "World", "@", "This", "@", "Is", "@", "A", "@", "Java", "@", "Program");
+
+        assertThat(textMixed.split(positiveLookAroundMultiDelimiterRegex)).containsExactly("@", "HelloWorld", "@", "This", ":", "Is", "@", "A", "#", "Java", "#", "Program");
+
+    }
+
+    @Test
+    public void givenString_splitAndKeepDelimiters_using_ApacheCommonsLang3StringUtils() {
+
+        assertThat(StringUtils.splitByCharacterType(textMixed2)).containsExactly("pg", "@", "no", ";", "10", "@", "hello", ";", "world", "@", "this", ";", "is", "@", "a", "#", "10", "words", ";", "J", "ava", "#", "P", "rogram");
+
+    }
+
+    @Test
+    public void givenString_splitAndKeepDelimiters_using_GuavaSplitter() {
+
+        assertThat(Splitter.onPattern(positivelookAroundRegex)
+            .splitToList(text)).containsExactly("Hello", "@", "World", "@", "This", "@", "Is", "@", "A", "@", "Java", "@", "Program");
+
+        assertThat(Splitter.on(Pattern.compile(positivelookAroundRegex))
+            .splitToList(text)).containsExactly("Hello", "@", "World", "@", "This", "@", "Is", "@", "A", "@", "Java", "@", "Program");
+
+        assertThat(Splitter.onPattern(positiveLookAroundMultiDelimiterRegex)
+            .splitToList(textMixed)).containsExactly("@", "HelloWorld", "@", "This", ":", "Is", "@", "A", "#", "Java", "#", "Program");
+
+        assertThat(Splitter.on(Pattern.compile(positiveLookAroundMultiDelimiterRegex))
+            .splitToList(textMixed)).containsExactly("@", "HelloWorld", "@", "This", ":", "Is", "@", "A", "#", "Java", "#", "Program");
+
+    }
+}

javaxval/src/test/java/com/baeldung/javaxval/bigdecimal/InvoiceUnitTest.java

@@ -1,18 +1,17 @@
 package com.baeldung.javaxval.bigdecimal;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
-import java.math.BigDecimal;
-import java.util.Set;
-
-import javax.validation.ConstraintViolation;
-import javax.validation.Validation;
-import javax.validation.Validator;
-
 import com.baeldung.javaxval.LocaleAwareUnitTest;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
+import javax.validation.ConstraintViolation;
+import javax.validation.Validation;
+import javax.validation.Validator;
+import java.math.BigDecimal;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
 public class InvoiceUnitTest extends LocaleAwareUnitTest {
 
     private static Validator validator;
@@ -24,41 +23,67 @@ public class InvoiceUnitTest extends LocaleAwareUnitTest {
     }
 
     @Test
-    public void whenPriceIntegerDigitLessThanThreeWithDecimalValue_thenShouldGiveConstraintViolations() {
-        Invoice invoice = new Invoice(new BigDecimal(10.21), "Book purchased");
+    public void whenLessThanThreeIntegerDigits_thenShouldNotGiveConstraintViolations() {
+        Invoice invoice = new Invoice(new BigDecimal("10.21"), "Book purchased");
         Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
-        assertThat(violations.size()).isEqualTo(1);
-        violations.forEach(action -> assertThat(action.getMessage()).isEqualTo("numeric value out of bounds (<3 digits>.<2 digits> expected)"));
+        assertThat(violations).isEmpty();
     }
 
     @Test
-    public void whenPriceIntegerDigitLessThanThreeWithIntegerValue_thenShouldNotGiveConstraintViolations() {
-        Invoice invoice = new Invoice(new BigDecimal(10), "Book purchased");
+    public void whenThreeIntegerDigits_thenShouldNotGiveConstraintViolations() {
+        Invoice invoice = new Invoice(new BigDecimal("102.21"), "Book purchased");
         Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
-        assertThat(violations.size()).isEqualTo(0);
+        assertThat(violations).isEmpty();
     }
 
     @Test
-    public void whenPriceIntegerDigitGreaterThanThree_thenShouldGiveConstraintViolations() {
-        Invoice invoice = new Invoice(new BigDecimal(1021.21), "Book purchased");
+    public void whenMoreThanThreeIntegerDigits_thenShouldGiveConstraintViolations() {
+        Invoice invoice = new Invoice(new BigDecimal("1021.21"), "Book purchased");
         Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
-        assertThat(violations.size()).isEqualTo(1);
-        violations.forEach(action -> assertThat(action.getMessage()).isEqualTo("numeric value out of bounds (<3 digits>.<2 digits> expected)"));
+        assertThat(violations).hasSize(1);
+        assertThat(violations)
+            .extracting("message")
+            .containsOnly("numeric value out of bounds (<3 digits>.<2 digits> expected)");
+    }
+
+    @Test
+    public void whenLessThanTwoFractionDigits_thenShouldNotGiveConstraintViolations() {
+        Invoice invoice = new Invoice(new BigDecimal("99.9"), "Book purchased");
+        Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
+        assertThat(violations).isEmpty();
+    }
+
+    @Test
+    public void whenTwoFractionDigits_thenShouldNotGiveConstraintViolations() {
+        Invoice invoice = new Invoice(new BigDecimal("99.99"), "Book purchased");
+        Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
+        assertThat(violations).isEmpty();
+    }
+
+    @Test
+    public void whenMoreThanTwoFractionDigits_thenShouldGiveConstraintViolations() {
+        Invoice invoice = new Invoice(new BigDecimal("99.999"), "Book purchased");
+        Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
+        assertThat(violations).hasSize(1);
+        assertThat(violations)
+            .extracting("message")
+            .containsOnly("numeric value out of bounds (<3 digits>.<2 digits> expected)");
     }
 
     @Test
     public void whenPriceIsZero_thenShouldGiveConstraintViolations() {
-        Invoice invoice = new Invoice(new BigDecimal(000.00), "Book purchased");
+        Invoice invoice = new Invoice(new BigDecimal("0.00"), "Book purchased");
         Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
-        assertThat(violations.size()).isEqualTo(1);
-        violations.forEach(action -> assertThat(action.getMessage()).isEqualTo("must be greater than 0.0"));
+        assertThat(violations).hasSize(1);
+        assertThat(violations)
+            .extracting("message")
+            .containsOnly("must be greater than 0.0");
     }
 
     @Test
     public void whenPriceIsGreaterThanZero_thenShouldNotGiveConstraintViolations() {
-        Invoice invoice = new Invoice(new BigDecimal(100.50), "Book purchased");
+        Invoice invoice = new Invoice(new BigDecimal("100.50"), "Book purchased");
         Set<ConstraintViolation<Invoice>> violations = validator.validate(invoice);
-        assertThat(violations.size()).isEqualTo(0);
+        assertThat(violations).isEmpty();
     }
-
 }

kubernetes/k8s-intro/README.md

@@ -16,3 +16,4 @@ If you get a valid response, then you're good to go.
 
 - [Paging and Async Calls with the Kubernetes API](https://www.baeldung.com/java-kubernetes-paging-async)
 - [Using Watch with the Kubernetes API](https://www.baeldung.com/java-kubernetes-watch)
+- [Using Namespaces and Selectors With the Kubernetes Java API](https://www.baeldung.com/java-kubernetes-namespaces-selectors)

kubernetes/k8s-intro/src/k8s/create-http-server.yml

@@ -0,0 +1,58 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: ns1
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: ns2
+---
+  apiVersion: apps/v1
+  kind: Deployment
+  metadata:
+    name: httpd
+    namespace: ns1
+    labels:
+      app: httpd
+      version: "1"
+  spec:
+    replicas: 3
+    selector:
+      matchLabels:
+        app: httpd
+    template:
+      metadata:
+        labels:
+          app: httpd
+      spec:
+        containers:
+        - name: main
+          image: httpd:alpine
+          ports:
+          - containerPort: 80
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: httpd
+  namespace: ns2
+  labels:
+    app: httpd
+    version: "2"
+    foo: bar
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: httpd
+  template:
+    metadata:
+      labels:
+        app: httpd
+    spec:
+      containers:
+      - name: main
+        image: httpd:alpine
+        ports:
+        - containerPort: 80

kubernetes/k8s-intro/src/main/java/com/baeldung/kubernetes/intro/ListPodsWithFieldSelectors.java

@@ -0,0 +1,68 @@
+/**
+ * 
+ */
+package com.baeldung.kubernetes.intro;
+
+
+import java.util.concurrent.TimeUnit;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.kubernetes.client.openapi.ApiClient;
+import io.kubernetes.client.openapi.apis.CoreV1Api;
+import io.kubernetes.client.openapi.models.V1NodeList;
+import io.kubernetes.client.openapi.models.V1PodList;
+import io.kubernetes.client.util.Config;
+import okhttp3.OkHttpClient;
+import okhttp3.logging.HttpLoggingInterceptor;
+
+/**
+ * @author Philippe
+ *
+ */
+public class ListPodsWithFieldSelectors {
+    
+    private static final Logger log = LoggerFactory.getLogger(ListPodsWithFieldSelectors.class);
+
+    /**
+     * @param args
+     */
+    public static void main(String[] args) throws Exception {
+        
+        ApiClient client  = Config.defaultClient();
+        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor(message -> log.info(message));
+        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
+        OkHttpClient newClient = client.getHttpClient()
+          .newBuilder()
+          .addInterceptor(interceptor)
+          .readTimeout(0, TimeUnit.SECONDS)
+          .build();
+        
+        client.setHttpClient(newClient);
+        CoreV1Api api = new CoreV1Api(client);
+        
+        String fs = createSelector(args);
+        V1PodList items = api.listPodForAllNamespaces(null, null, fs, null, null, null, null, null, 10, false);
+        items.getItems()
+          .stream()
+          .map((pod) -> pod.getMetadata().getName() )
+          .forEach((name) -> System.out.println("name=" + name));
+        
+    }
+
+    private static String createSelector(String[] args) {
+
+        StringBuilder b = new StringBuilder();
+        for( int i =  0 ; i < args.length; i++ ) {
+            if( b.length() > 0 ) {
+                b.append(',');
+            }
+            
+            b.append(args[i]);
+        }
+        
+        return b.toString();
+    }
+
+}

kubernetes/k8s-intro/src/main/java/com/baeldung/kubernetes/intro/ListPodsWithLabelSelectors.java

@@ -0,0 +1,68 @@
+/**
+ * 
+ */
+package com.baeldung.kubernetes.intro;
+
+
+import java.util.concurrent.TimeUnit;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.kubernetes.client.openapi.ApiClient;
+import io.kubernetes.client.openapi.apis.CoreV1Api;
+import io.kubernetes.client.openapi.models.V1NodeList;
+import io.kubernetes.client.openapi.models.V1PodList;
+import io.kubernetes.client.util.Config;
+import okhttp3.OkHttpClient;
+import okhttp3.logging.HttpLoggingInterceptor;
+
+/**
+ * @author Philippe
+ *
+ */
+public class ListPodsWithLabelSelectors {
+    
+    private static final Logger log = LoggerFactory.getLogger(ListPodsWithLabelSelectors.class);
+
+    /**
+     * @param args
+     */
+    public static void main(String[] args) throws Exception {
+        
+        ApiClient client  = Config.defaultClient();
+        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor(message -> log.info(message));
+        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
+        OkHttpClient newClient = client.getHttpClient()
+          .newBuilder()
+          .addInterceptor(interceptor)
+          .readTimeout(0, TimeUnit.SECONDS)
+          .build();
+        
+        client.setHttpClient(newClient);
+        CoreV1Api api = new CoreV1Api(client);
+
+        String selector = createSelector(args);
+        V1PodList items = api.listPodForAllNamespaces(null, null, null, selector, null, null, null, null, 10, false);
+        items.getItems()
+          .stream()
+          .map((pod) -> pod.getMetadata().getName() )
+          .forEach((name) -> System.out.println("name=" + name));
+        
+    }
+    
+    private static String createSelector(String[] args) {
+
+        StringBuilder b = new StringBuilder();
+        for( int i =  0 ; i < args.length; i++ ) {
+            if( b.length() > 0 ) {
+                b.append(',');
+            }
+            
+            b.append(args[i]);
+        }
+        
+        return b.toString();
+    }
+    
+}

kubernetes/k8s-intro/src/main/java/com/baeldung/kubernetes/intro/ListPodsWithNamespaces.java

@@ -0,0 +1,52 @@
+/**
+ * 
+ */
+package com.baeldung.kubernetes.intro;
+
+
+import java.util.concurrent.TimeUnit;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.kubernetes.client.openapi.ApiClient;
+import io.kubernetes.client.openapi.apis.CoreV1Api;
+import io.kubernetes.client.openapi.models.V1NodeList;
+import io.kubernetes.client.openapi.models.V1PodList;
+import io.kubernetes.client.util.Config;
+import okhttp3.OkHttpClient;
+import okhttp3.logging.HttpLoggingInterceptor;
+
+/**
+ * @author Philippe
+ *
+ */
+public class ListPodsWithNamespaces {
+    
+    private static final Logger log = LoggerFactory.getLogger(ListPodsWithNamespaces.class);
+
+    /**
+     * @param args
+     */
+    public static void main(String[] args) throws Exception {
+        
+        ApiClient client  = Config.defaultClient();
+        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor(message -> log.info(message));
+        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
+        OkHttpClient newClient = client.getHttpClient()
+          .newBuilder()
+          .addInterceptor(interceptor)
+          .readTimeout(0, TimeUnit.SECONDS)
+          .build();
+        
+        client.setHttpClient(newClient);
+        CoreV1Api api = new CoreV1Api(client);
+        String namespace = "ns1";
+        V1PodList items = api.listNamespacedPod(namespace,null, null, null, null, null, null, null, null, 10, false);
+        items.getItems()
+          .stream()
+          .map((pod) -> pod.getMetadata().getName() )
+          .forEach((name) -> System.out.println("name=" + name));
+        
+    }
+}