Merge remote-tracking branch 'upstream/master' into feature/BAEL-6695-BooleanValidation

.github/ISSUE_TEMPLATE/issue_report.md

@@ -5,7 +5,7 @@ title: '[ISSUE] '
 ---
 
 **Article and Module Links**
-A link to the affected article and the affected module. The link to the module is the one in the "over on GitHub" standard phrase.
+A link to the affected article and the affected module. You can find the link to the module in the Conclusion section in the "on Github" standard phase.
 
 **Describe the Issue**
 A clear and concise description of what the issue is.
@@ -30,9 +30,3 @@ If applicable, add screenshots to help explain your problem.
 
 **Additional Context**
 Add any other context about the issue here.
-
-Note that, unfortunately, we can only help with issues that are specifically and directly related to the article - not with your own, custom application.
-
-StackOverflow is a great place to ask more general questions.
-
-That's primarily because we get a large number of questions and - while we do try to go through as much as everything and help wherever we can, we can't really get back to all of them.

apache-poi-3/README.md

@@ -0,0 +1,3 @@
+## Relevant Articles
+- [How To Convert Excel Data Into List Of Java Objects](https://www.baeldung.com/java-convert-excel-data-into-list)
+- [Expand Columns with Apache POI](https://www.baeldung.com/java-apache-poi-expand-columns)

core-java-modules/core-java-16/README.md

@@ -5,3 +5,4 @@
 - [Collecting Stream Elements into a List in Java](https://www.baeldung.com/java-stream-to-list-collecting)
 - [New Features in Java 16](https://www.baeldung.com/java-16-new-features)
 - [Guide to Java 8 groupingBy Collector](https://www.baeldung.com/java-groupingby-collector)
+- [Value-Based Classes in Java](https://www.baeldung.com/java-value-based-classes)

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

@@ -1,2 +1,3 @@
 ## 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)

core-java-modules/core-java-21/pom.xml

@@ -12,6 +12,12 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <properties>
+        <maven.compiler.source.version>21</maven.compiler.source.version>
+        <maven.compiler.target.version>21</maven.compiler.target.version>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
     <build>
         <plugins>
             <plugin>
@@ -20,14 +26,22 @@
                 <configuration>
                     <source>21</source>
                     <target>21</target>
-                    <compilerArgs>--enable-preview</compilerArgs>
+                    <!-- Needed due to a bug with JDK 21, described here: https://issues.apache.org/jira/browse/MCOMPILER-546?page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel&focusedCommentId=17767513 -->
+                    <debug>false</debug>
+                    <compilerArgs>
+                        <arg>--enable-preview</arg>
+                    </compilerArgs>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <configuration>
+                    <argLine>--enable-preview</argLine>
+                </configuration>
+            </plugin>
+
         </plugins>
     </build>
-    <properties>
-        <maven.compiler.source.version>21</maven.compiler.source.version>
-        <maven.compiler.target.version>21</maven.compiler.target.version>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    </properties>
+
 </project>

core-java-modules/core-java-21/src/main/java/com/baeldung/unnamed/variables/Car.java

@@ -0,0 +1,11 @@
+package com.baeldung.unnamed.variables;
+
+public record Car<T extends Engine>(String name, String color, T engine) { }
+
+abstract class Engine { }
+
+class GasEngine extends Engine { }
+
+class ElectricEngine extends Engine { }
+
+class HybridEngine extends Engine { }

core-java-modules/core-java-21/src/main/java/com/baeldung/unnamed/variables/UnnamedPatterns.java

@@ -0,0 +1,50 @@
+package com.baeldung.unnamed.variables;
+
+public class UnnamedPatterns {
+
+    static String getObjectsColorWithNamedPattern(Object object) {
+        if (object instanceof Car(String name, String color, Engine engine)) {
+            return color;
+        }
+        return "No color!";
+    }
+
+    static String getObjectsColorWithUnnamedPattern(Object object) {
+        if (object instanceof Car(_, String color, _)) {
+            return color;
+        }
+        return "No color!";
+    }
+
+    static String getObjectsColorWithSwitchAndNamedPattern(Object object) {
+        return switch (object) {
+            case Car(String name, String color, Engine engine) -> color;
+            default -> "No color!";
+        };
+    }
+
+    static String getObjectsColorWithSwitchAndUnnamedPattern(Object object) {
+        return switch (object) {
+            case Car(_, String color, _) -> color;
+            default -> "No color!";
+        };
+    }
+
+    static String getEngineTypeWithNamedPattern(Car<?> car) {
+        return switch (car) {
+            case Car(String name, String color, GasEngine engine) -> "gas";
+            case Car(String name, String color, ElectricEngine engine) -> "electric";
+            case Car(String name, String color, HybridEngine engine) -> "hybrid";
+            default -> "none";
+        };
+    }
+
+    static String getEngineTypeWithUnnamedPattern(Car<?> car) {
+        return switch (car) {
+            case Car(_, _, GasEngine _) -> "gas";
+            case Car(_, _, ElectricEngine _) -> "electric";
+            case Car(_, _, HybridEngine _) -> "hybrid";
+            default -> "none";
+        };
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/unnamed/variables/UnnamedVariables.java

@@ -0,0 +1,134 @@
+package com.baeldung.unnamed.variables;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+
+class Transaction implements AutoCloseable {
+
+    @Override
+    public void close() {
+        System.out.println("Closed!");
+    }
+}
+
+public class UnnamedVariables {
+
+    static int countCarsOverLimitWithNamedVariable(Collection<Car<?>> cars, int limit) {
+        var total = 0;
+        var totalOverLimit = 0;
+        for (var car : cars) {
+            total++;
+            if (total > limit) {
+                totalOverLimit++;
+                // side effect
+            }
+        }
+        return totalOverLimit;
+    }
+
+    static int countCarsOverLimitWithUnnamedVariable(Collection<Car<?>> cars, int limit) {
+        var total = 0;
+        var totalOverLimit = 0;
+        for (var _ : cars) {
+            total++;
+            if (total > limit) {
+                totalOverLimit++;
+                // side effect
+            }
+        }
+        return totalOverLimit;
+    }
+
+    static void sendNotificationToCarsWithNamedVariable(Collection<Car<?>> cars) {
+        sendOneTimeNotification();
+        for (int i = 0; i < cars.size(); i++) {
+            // Notify car
+        }
+    }
+
+    static void sendNotificationToCarsWithUnnamedVariable(Collection<Car<?>> cars) {
+        for (int i = 0, _ = sendOneTimeNotification(); i < cars.size(); i++) {
+            // Notify car
+        }
+    }
+
+    private static int sendOneTimeNotification() {
+        System.out.println("Sending one time notification!");
+        return 1;
+    }
+
+    static Car<?> removeThreeCarsAndReturnFirstRemovedWithNamedVariables(Queue<Car<?>> cars) {
+        var x = cars.poll();
+        var y = cars.poll();
+        var z = cars.poll();
+        return x;
+    }
+
+    static Car<?> removeThreeCarsAndReturnFirstRemovedWithUnnamedVariables(Queue<Car<?>> cars) {
+        var car = cars.poll();
+        var _ = cars.poll();
+        var _ = cars.poll();
+        return car;
+    }
+
+    static void handleCarExceptionWithNamedVariables(Car<?> car) {
+        try {
+            someOperationThatFails(car);
+        } catch (IllegalStateException ex) {
+            System.out.println("Got an illegal state exception for: " + car.name());
+        } catch (RuntimeException ex) {
+            System.out.println("Got a runtime exception!");
+        }
+    }
+
+    static void handleCarExceptionWithUnnamedVariables(Car<?> car) {
+        try {
+            someOperationThatFails(car);
+        } catch (IllegalStateException | NumberFormatException _) {
+            System.out.println("Got an illegal state exception for: " + car.name());
+        } catch (RuntimeException _) {
+            System.out.println("Got a runtime exception!");
+        }
+    }
+
+    static void obtainTransactionAndUpdateCarWithNamedVariables(Car<?> car) {
+        try (var transaction = new Transaction()) {
+            updateCar(car);
+        }
+    }
+
+    static void obtainTransactionAndUpdateCarWithUnnamedVariables(Car<?> car) {
+        try (var _ = new Transaction()) {
+            updateCar(car);
+        }
+    }
+
+    static void updateCar(Car<?> car) {
+        // Some update logic
+        System.out.println("Car updated!");
+    }
+
+    static Map<String, List<Car<?>>> getCarsByFirstLetterWithNamedVariables(List<Car<?>> cars) {
+        Map<String, List<Car<?>>> carMap = new HashMap<>();
+        cars.forEach(car ->
+            carMap.computeIfAbsent(car.name().substring(0, 1), firstLetter -> new ArrayList<>()).add(car)
+        );
+        return carMap;
+    }
+
+    static Map<String, List<Car<?>>> getCarsByFirstLetterWithUnnamedVariables(List<Car<?>> cars) {
+        Map<String, List<Car<?>>> carMap = new HashMap<>();
+        cars.forEach(car ->
+            carMap.computeIfAbsent(car.name().substring(0, 1), _ -> new ArrayList<>()).add(car)
+        );
+        return carMap;
+    }
+
+    private static void someOperationThatFails(Car<?> car) {
+        throw new IllegalStateException("Triggered exception for: " + car.name());
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/unnamedclasses/HelloWorld.java

@@ -0,0 +1,3 @@
+void main() {
+    System.out.println("Hello, World!");
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/unnamedclasses/HelloWorldChild.java

@@ -0,0 +1,7 @@
+package com.baeldung.unnamedclasses;
+
+public class HelloWorldChild extends HelloWorldSuper {
+    void main() {
+        System.out.println("Hello, World!");
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/unnamedclasses/HelloWorldSuper.java

@@ -0,0 +1,7 @@
+package com.baeldung.unnamedclasses;
+
+public class HelloWorldSuper {
+    public static void main(String[] args) {
+        System.out.println("Hello from the superclass");
+    }
+}

core-java-modules/core-java-21/src/main/java/com/baeldung/unnamedclasses/HelloWorldWithMethod.java

@@ -0,0 +1,6 @@
+private String getMessage() {
+    return "Hello, World!";
+}
+void main() {
+    System.out.println(getMessage());
+}

core-java-modules/core-java-21/src/test/java/com/baeldung/unnamed/variables/CarScenario.java

@@ -0,0 +1,13 @@
+package com.baeldung.unnamed.variables;
+
+import java.util.List;
+
+class CarScenario {
+
+    protected final List<Car<?>> cars = List.of(
+        new Car<>("Mitsubishi", "blue", new GasEngine()),
+        new Car<>("Toyota", "red", new ElectricEngine()),
+        new Car<>("Jaguar", "white", new HybridEngine())
+    );
+
+}

core-java-modules/core-java-21/src/test/java/com/baeldung/unnamed/variables/UnnamedPatternsUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.unnamed.variables;
+
+import static com.baeldung.unnamed.variables.UnnamedPatterns.getEngineTypeWithNamedPattern;
+import static com.baeldung.unnamed.variables.UnnamedPatterns.getEngineTypeWithUnnamedPattern;
+import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithNamedPattern;
+import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithSwitchAndNamedPattern;
+import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithSwitchAndUnnamedPattern;
+import static com.baeldung.unnamed.variables.UnnamedPatterns.getObjectsColorWithUnnamedPattern;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class UnnamedPatternsUnitTest extends CarScenario {
+
+    @Test
+    public void whenExtractingColorWithNamedPatterns_thenReturnBlue() {
+        assertEquals("blue", getObjectsColorWithNamedPattern(cars.get(0)));
+    }
+
+    @Test
+    public void whenExtractingColorWithUnnamedPatterns_thenReturnBlue() {
+        assertEquals("blue", getObjectsColorWithUnnamedPattern(cars.get(0)));
+    }
+
+    @Test
+    public void whenExtractingColorWithSwitchAndNamedPatterns_thenReturnBlue() {
+        assertEquals("blue", getObjectsColorWithSwitchAndNamedPattern(cars.get(0)));
+    }
+
+    @Test
+    public void whenExtractingColorWithSwitchAndUnnamedPatterns_thenReturnBlue() {
+        assertEquals("blue", getObjectsColorWithSwitchAndUnnamedPattern(cars.get(0)));
+    }
+
+    @Test
+    public void whenExtractingEngineTypeWithNamedPatterns_thenReturnGas() {
+        assertEquals("gas", getEngineTypeWithNamedPattern(cars.get(0)));
+    }
+
+    @Test
+    public void whenExtractingEngineTypeWithUnnamedPatterns_thenReturnGas() {
+        assertEquals("gas", getEngineTypeWithUnnamedPattern(cars.get(0)));
+    }
+}

core-java-modules/core-java-21/src/test/java/com/baeldung/unnamed/variables/UnnamedVariablesUnitTest.java

@@ -0,0 +1,93 @@
+package com.baeldung.unnamed.variables;
+
+import static com.baeldung.unnamed.variables.UnnamedVariables.countCarsOverLimitWithNamedVariable;
+import static com.baeldung.unnamed.variables.UnnamedVariables.countCarsOverLimitWithUnnamedVariable;
+import static com.baeldung.unnamed.variables.UnnamedVariables.getCarsByFirstLetterWithNamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.getCarsByFirstLetterWithUnnamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.handleCarExceptionWithNamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.handleCarExceptionWithUnnamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.obtainTransactionAndUpdateCarWithNamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.obtainTransactionAndUpdateCarWithUnnamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.removeThreeCarsAndReturnFirstRemovedWithNamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.removeThreeCarsAndReturnFirstRemovedWithUnnamedVariables;
+import static com.baeldung.unnamed.variables.UnnamedVariables.sendNotificationToCarsWithNamedVariable;
+import static com.baeldung.unnamed.variables.UnnamedVariables.sendNotificationToCarsWithUnnamedVariable;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.LinkedList;
+
+import org.junit.jupiter.api.Test;
+
+public class UnnamedVariablesUnitTest extends CarScenario {
+
+    @Test
+    public void whenCountingCarsOverLimitWithNamedVariables_thenShouldReturnOne() {
+        assertEquals(1, countCarsOverLimitWithNamedVariable(cars, 2));
+    }
+
+    @Test
+    public void whenCountingCarsOverLimitWithUnnamedVariables_thenShouldReturnOne() {
+        assertEquals(1, countCarsOverLimitWithUnnamedVariable(cars, 2));
+    }
+
+    @Test
+    public void whenNotifyingCarsWithNamedVariables_thenShouldNotFail() {
+        assertDoesNotThrow(() -> sendNotificationToCarsWithNamedVariable(cars));
+    }
+
+    @Test
+    public void whenNotifyingCarsWithUnnamedVariables_thenShouldNotFail() {
+        assertDoesNotThrow(() -> sendNotificationToCarsWithUnnamedVariable(cars));
+    }
+
+    @Test
+    public void whenPollingCarsWithNamedVariables_thenReturnFirstOneAndEmptyQueue() {
+        var carQueue = new LinkedList<>(cars);
+        assertEquals("Mitsubishi", removeThreeCarsAndReturnFirstRemovedWithNamedVariables(carQueue).name());
+        assertEquals(0, carQueue.size());
+    }
+
+    @Test
+    public void whenPollingCarsWithUnnamedVariables_thenReturnFirstOneAndEmptyQueue() {
+        var carQueue = new LinkedList<>(cars);
+        assertEquals("Mitsubishi", removeThreeCarsAndReturnFirstRemovedWithUnnamedVariables(carQueue).name());
+        assertEquals(0, carQueue.size());
+    }
+
+    @Test
+    public void whenHandlingExceptionWithNamedVariables_thenNoExceptionIsThrown() {
+        assertDoesNotThrow(() -> handleCarExceptionWithNamedVariables(cars.get(0)));
+    }
+
+    @Test
+    public void whenHandlingExceptionWithUnnamedVariables_thenNoExceptionIsThrown() {
+        assertDoesNotThrow(() -> handleCarExceptionWithUnnamedVariables(cars.get(0)));
+    }
+
+    @Test
+    public void whenHandlingTransactionUpdateWithNamedVariables_thenNoExceptionIsThrown() {
+        assertDoesNotThrow(() -> obtainTransactionAndUpdateCarWithNamedVariables(cars.get(0)));
+    }
+
+    @Test
+    public void whenHandlingTransactionUpdateWithUnnamedVariables_thenNoExceptionIsThrown() {
+        assertDoesNotThrow(() -> obtainTransactionAndUpdateCarWithUnnamedVariables(cars.get(0)));
+    }
+
+    @Test
+    public void whenGettingCarsByFirstLetterWithNamedVariables_thenHaveThreeKeys() {
+        var carsByLetter = getCarsByFirstLetterWithNamedVariables(cars);
+        assertEquals(1, carsByLetter.get("M").size());
+        assertEquals(1, carsByLetter.get("T").size());
+        assertEquals(1, carsByLetter.get("J").size());
+    }
+
+    @Test
+    public void whenGettingCarsByFirstLetterWithUnnamedVariables_thenHaveThreeKeys() {
+        var carsByLetter = getCarsByFirstLetterWithUnnamedVariables(cars);
+        assertEquals(1, carsByLetter.get("M").size());
+        assertEquals(1, carsByLetter.get("T").size());
+        assertEquals(1, carsByLetter.get("J").size());
+    }
+}

core-java-modules/core-java-9-streams/README.md

@@ -4,3 +4,4 @@ This module contains articles about Java 9 streams
 
 ### Relevant Articles: 
 - [How to Break from Java Stream forEach](https://www.baeldung.com/java-break-stream-foreach)
+- [Creating Stream of Regex Matches](https://www.baeldung.com/java-stream-regex-matches)

core-java-modules/core-java-arrays-guides/README.md

@@ -9,3 +9,4 @@ This module contains complete guides about arrays in Java
 - [Guide to ArrayStoreException](https://www.baeldung.com/java-arraystoreexception)
 - [Creating a Generic Array in Java](https://www.baeldung.com/java-generic-array)
 - [Maximum Size of Java Arrays](https://www.baeldung.com/java-arrays-max-size)
+- [Merge Two Arrays and Remove Duplicates in Java](https://www.baeldung.com/java-merge-two-arrays-delete-duplicates)

core-java-modules/core-java-arrays-operations-advanced-2/README.md

@@ -0,0 +1,2 @@
+## Relevant Articles
+- [Find the Middle Element of an Array in Java](https://www.baeldung.com/java-array-middle-item)

core-java-modules/core-java-arrays-operations-advanced/README.md

@@ -14,4 +14,3 @@ This module contains articles about advanced operations on arrays in Java. They
 - [Slicing Arrays in Java](https://www.baeldung.com/java-slicing-arrays)
 - [Combining Two or More Byte Arrays](https://www.baeldung.com/java-concatenate-byte-arrays)
 - [Calculating the Sum of Two Arrays in Java](https://www.baeldung.com/java-sum-arrays-element-wise)
-- [Find the Middle Element of an Array in Java](https://www.baeldung.com/java-array-middle-item)

core-java-modules/core-java-char/src/test/java/com/baeldung/incrementchar/IncrementCharUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.incrementchar;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+class IncrementCharUnitTest {
+    @Test
+    void whenUsingForLoop_thenGenerateCharacters(){
+        final List<Character> allCapitalCharacters = Arrays.asList('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z');
+        List<Character> characters = new ArrayList<>();
+        for (char character = 'A'; character <= 'Z'; character++) {
+            characters.add(character);
+        }
+        Assertions.assertEquals(characters, allCapitalCharacters);
+    }
+
+    @Test
+    void whenUsingStreams_thenGenerateCharacters() {
+        final List<Character> allCapitalCharacters = Arrays.asList('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z');
+        final List<Character> characters = IntStream.rangeClosed('A', 'Z').mapToObj(c -> (char) c).collect(Collectors.toList());
+        Assertions.assertEquals(characters, allCapitalCharacters);
+    }
+}

core-java-modules/core-java-collections-5/src/main/java/com/baeldung/skippingfirstelement/SkipFirstElementExample.java

@@ -0,0 +1,126 @@
+package com.baeldung.skippingfirstelement;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
+public class SkipFirstElementExample {
+
+    private final List<String> stringList = new ArrayList<>();
+    private final Set<String> stringSet = new HashSet<>();
+    private final Map<String, String> stringMap = new HashMap<>();
+
+    public SkipFirstElementExample() {
+        // Initializing a List
+        stringList.add("Monday");
+        stringList.add("Tuesday");
+        stringList.add("Wednesday");
+        stringList.add("Thursday");
+        stringList.add("Friday");
+        stringList.add("Saturday");
+        stringList.add("Sunday");
+        // Initializing a Set
+        stringSet.add("Monday");
+        stringSet.add("Tuesday");
+        stringSet.add("Wednesday");
+        stringSet.add("Thursday");
+        stringSet.add("Friday");
+        stringSet.add("Saturday");
+        stringSet.add("Sunday");
+        // Initializing a Map
+        stringMap.put("Monday", "The day when coffee is a life support system.");
+        stringMap.put("Tuesday", "The day you realize that Monday's optimism was a lie.");
+        stringMap.put("Wednesday", "Hump Day, or as it's known, the 'Is it Friday yet?' day.");
+        stringMap.put("Thursday", "The day that says, 'Hold my beer, Friday is coming!'");
+        stringMap.put("Friday", "The golden child of the weekdays. The superhero of the workweek.");
+        stringMap.put("Saturday", "The day of rest? More like the day of 'What can I binge-watch next?'");
+        stringMap.put("Sunday", "The day before you have to adult again.");
+    }
+
+    void skippingFirstElementInListWithForLoop(List<String> stringList) {
+        for (int i = 1; i < stringList.size(); i++) {
+            process(stringList.get(i));
+        }
+    }
+
+    void skippingFirstElementInListWithWhileLoop(List<String> stringList) {
+        final Iterator<String> iterator = stringList.iterator();
+        if (iterator.hasNext()) {
+            iterator.next();
+        }
+        while (iterator.hasNext()) {
+            process(iterator.next());
+        }
+    }
+
+    void skippingFirstElementInSetWithWhileLoop(Set<String> stringSet) {
+        final Iterator<String> iterator = stringSet.iterator();
+        if (iterator.hasNext()) {
+            iterator.next();
+        }
+        while (iterator.hasNext()) {
+            process(iterator.next());
+        }
+    }
+
+    void skippingFirstElementInListWithWhileLoopStoringFirstElement(List<String> stringList) {
+        final Iterator<String> iterator = stringList.iterator();
+        String firstElement = null;
+        if (iterator.hasNext()) {
+            firstElement = iterator.next();
+        }
+        while (iterator.hasNext()) {
+            process(iterator.next());
+            // additional logic using fistElement
+        }
+    }
+
+    void skippingFirstElementInMapWithStreamSkip(Map<String, String> stringMap) {
+        stringMap.entrySet().stream().skip(1).forEach(this::process);
+    }
+
+    void skippingFirstElementInListWithSubList(List<String> stringList) {
+        for (final String element : stringList.subList(1, stringList.size())) {
+            process(element);
+        }
+    }
+
+    void skippingFirstElementInListWithForLoopWithAdditionalCheck(List<String> stringList) {
+        for (int i = 0; i < stringList.size(); i++) {
+            if (i == 0) {
+                // do something else
+            } else {
+                process(stringList.get(i));
+            }
+        }
+    }
+
+    void skippingFirstElementInListWithWhileLoopWithCounter(List<String> stringList) {
+        int counter = 0;
+        while (counter < stringList.size()) {
+            if (counter != 0) {
+                process(stringList.get(counter));
+            }
+            ++counter;
+        }
+    }
+
+    void skippingFirstElementInListWithReduce(List<String> stringList) {
+        stringList.stream().reduce((skip, element) -> {
+            process(element);
+            return element;
+        });
+    }
+
+    protected void process(String string) {
+        System.out.println(string);
+    }
+    protected void process(Entry<String, String> mapEntry) {
+        System.out.println(mapEntry);
+    }
+}

core-java-modules/core-java-collections-5/src/test/java/com/baeldung/skippingfirstelement/SkipFirstElementExampleUnitTest.java

@@ -0,0 +1,122 @@
+package com.baeldung.skippingfirstelement;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Stream;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+@EnabledForJreRange(min = JRE.JAVA_9)
+class SkipFirstElementExampleUnitTest {
+
+    private static TestableSkipFirstElement testableSkip = new TestableSkipFirstElement();
+
+    @BeforeEach
+    void setup() {
+        testableSkip.reset();
+    }
+
+    private static Stream<Arguments> listProvider() {
+        return Stream.of(
+            Arguments.of(
+                List.of("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"),
+                List.of("Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"))
+        );
+    }
+
+    private static Stream<Arguments> mapProvider() {
+        return Stream.of(
+            Arguments.of(
+                Map.of(
+                    "Monday", "The day when coffee is a life support system.",
+                    "Tuesday", "The day you realize that Monday's optimism was a lie.",
+                    "Wednesday", "Hump Day, or as it's known, the 'Is it Friday yet?' day.",
+                    "Thursday", "The day that says, 'Hold my beer, Friday is coming!'",
+                    "Friday", "The golden child of the weekdays. The superhero of the workweek.",
+                    "Saturday", "The day of rest? More like the day of 'What can I binge-watch next?'",
+                    "Sunday", "The day before you have to adult again."
+                )
+            )
+        );
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInListWithForLoop(List<String> input, List<String> expected) {
+        testableSkip.skippingFirstElementInListWithForLoop(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual, expected);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInListWithWhileLoop(List<String> input, List<String> expected) {
+        testableSkip.skippingFirstElementInListWithWhileLoop(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual, expected);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInSetWithWhileLoop(List<String> input) {
+        testableSkip.skippingFirstElementInSetWithWhileLoop(new HashSet<>(input));
+        Set<?> actual = new HashSet<>(testableSkip.getResult());
+        assertEquals(actual.size(), input.size() - 1);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInListWithWhileLoopStoringFirstElement(List<String> input, List<String> expected) {
+        testableSkip.skippingFirstElementInListWithWhileLoopStoringFirstElement(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual, expected);
+    }
+
+    @ParameterizedTest
+    @MethodSource("mapProvider")
+    void skippingFirstElementInMapWithStreamSkip(Map<String, String> input) {
+        testableSkip.skippingFirstElementInMapWithStreamSkip(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual.size(), input.size() - 1);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInListWithSubList(List<String> input, List<String> expected) {
+        testableSkip.skippingFirstElementInListWithSubList(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual, expected);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInListWithForLoopWithAdditionalCheck(List<String> input, List<String> expected) {
+        testableSkip.skippingFirstElementInListWithForLoopWithAdditionalCheck(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual, expected);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInListWithWhileLoopWithCounter(List<String> input, List<String> expected) {
+        testableSkip.skippingFirstElementInListWithWhileLoopWithCounter(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual, expected);
+    }
+
+    @ParameterizedTest
+    @MethodSource("listProvider")
+    void skippingFirstElementInListWithReduce(List<String> input, List<String> expected) {
+        testableSkip.skippingFirstElementInListWithReduce(input);
+        List<?> actual = testableSkip.getResult();
+        assertEquals(actual, expected);
+    }
+}

core-java-modules/core-java-collections-5/src/test/java/com/baeldung/skippingfirstelement/TestableSkip.java

@@ -0,0 +1,10 @@
+package com.baeldung.skippingfirstelement;
+
+import java.util.List;
+
+public interface TestableSkip {
+
+    void reset();
+
+    List<?> getResult();
+}

core-java-modules/core-java-collections-5/src/test/java/com/baeldung/skippingfirstelement/TestableSkipFirstElement.java

@@ -0,0 +1,37 @@
+package com.baeldung.skippingfirstelement;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map.Entry;
+
+public class TestableSkipFirstElement extends SkipFirstElementExample implements TestableSkip {
+
+
+    private List<String> processedList = new ArrayList<>();
+    private List<Entry<String, String>> processedEntryList = new ArrayList<>();
+
+    @Override
+    public void process(String string) {
+        processedList.add(string);
+    }
+
+    @Override
+    public void process(Entry<String, String> stringEntry) {
+        processedEntryList.add(stringEntry);
+    }
+
+    @Override
+    public void reset() {
+        processedList.clear();
+        processedEntryList.clear();
+    }
+
+    @Override
+    public List<?> getResult() {
+        if (!processedList.isEmpty())
+            return processedList;
+        return processedEntryList;
+    }
+
+
+}

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

@@ -0,0 +1,6 @@
+## Core Java Collections ArrayList
+
+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)

core-java-modules/core-java-collections-array-list-2/pom.xml

@@ -0,0 +1,32 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-collections-array-list-2</artifactId>
+    <name>core-java-collections-array-list-2</name>
+    <packaging>jar</packaging>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${maven-compiler-plugin.source}</source>
+                    <target>${maven-compiler-plugin.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+    
+    <properties>
+        <maven-compiler-plugin.source>17</maven-compiler-plugin.source>
+        <maven-compiler-plugin.target>17</maven-compiler-plugin.target>
+    </properties>
+</project>

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/AlternativeMultipeTypeList.java

@@ -0,0 +1,51 @@
+package com.baeldung.list.multipleobjecttypes;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.function.Predicate;
+
+public class AlternativeMultipeTypeList {
+
+    public static void main(String[] args) {
+        // List of Parent Class
+        ArrayList<Number> myList = new ArrayList<>();
+        myList.add(1.2);
+        myList.add(2);
+        myList.add(-3.5);
+
+        // List of Interface type
+        ArrayList<Map> diffMapList = new ArrayList<>();
+        diffMapList.add(new HashMap<>());
+        diffMapList.add(new TreeMap<>());
+        diffMapList.add(new LinkedHashMap<>());
+
+        // List of Custom Object
+        ArrayList<CustomObject> objList = new ArrayList<>();
+        objList.add(new CustomObject("String"));
+        objList.add(new CustomObject(2));
+
+        // List via Functional Interface
+        List<Object> dataList = new ArrayList<>();
+
+        Predicate<Object> myPredicate = inputData -> (inputData instanceof String || inputData instanceof Integer);
+
+        UserFunctionalInterface myInterface = (listObj, data) -> {
+            if (myPredicate.test(data))
+                listObj.add(data);
+            else
+                System.out.println("Skipping input as data not allowed for class: " + data.getClass()
+                    .getSimpleName());
+            return listObj;
+        };
+
+        myInterface.addToList(dataList, Integer.valueOf(2));
+        myInterface.addToList(dataList, Double.valueOf(3.33));
+        myInterface.addToList(dataList, "String Value");
+        myInterface.printList(dataList);
+    }
+
+}

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/CustomObject.java

@@ -0,0 +1,22 @@
+package com.baeldung.list.multipleobjecttypes;
+
+public class CustomObject {
+    String classData;
+    Integer intData;
+
+    CustomObject(String classData) {
+        this.classData = classData;
+    }
+
+    CustomObject(Integer intData) {
+        this.intData = intData;
+    }
+
+    public String getClassData() {
+        return this.classData;
+    }
+
+    public Integer getIntData() {
+        return this.intData;
+    }
+}

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/MultipleObjectTypeArrayList.java

@@ -0,0 +1,40 @@
+package com.baeldung.list.multipleobjecttypes;
+
+import java.math.BigInteger;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class MultipleObjectTypeArrayList {
+
+    public static void main(String[] args) {
+
+        ArrayList<Object> multiTypeList = new ArrayList<>();
+
+        multiTypeList.add(Integer.valueOf(10));
+        multiTypeList.add(Double.valueOf(11.5));
+        multiTypeList.add("String Data");
+        multiTypeList.add(Arrays.asList(1, 2, 3));
+        multiTypeList.add(new CustomObject("Class Data"));
+        multiTypeList.add(BigInteger.valueOf(123456789));
+        multiTypeList.add(LocalDate.of(2023, 9, 19));
+
+        for (Object dataObj : multiTypeList) {
+            if (dataObj instanceof Integer intData)
+                System.out.println("Integer Data : " + intData);
+            else if (dataObj instanceof Double doubleData)
+                System.out.println("Double Data : " + doubleData);
+            else if (dataObj instanceof String stringData)
+                System.out.println("String Data : " + stringData);
+            else if (dataObj instanceof List<?> intList)
+                System.out.println("List Data : " + intList);
+            else if (dataObj instanceof CustomObject customObj)
+                System.out.println("CustomObject Data : " + customObj.getClassData());
+            else if (dataObj instanceof BigInteger bigIntData)
+                System.out.println("BigInteger Data : " + bigIntData);
+            else if (dataObj instanceof LocalDate localDate)
+                System.out.println("LocalDate Data : " + localDate.toString());
+        }
+    }
+}

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/UserFunctionalInterface.java

@@ -0,0 +1,18 @@
+package com.baeldung.list.multipleobjecttypes;
+
+import java.util.List;
+
+@FunctionalInterface
+public interface UserFunctionalInterface {
+
+    List<Object> addToList(List<Object> list, Object data);
+
+    default void printList(List<Object> dataList) {
+        for (Object data : dataList) {
+            if (data instanceof String stringData)
+                System.out.println("String Data: " + stringData);
+            if (data instanceof Integer intData)
+                System.out.println("Integer Data: " + intData);
+        }
+    }
+}

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

@@ -0,0 +1,2 @@
+## Relevant Articles
+- [Check if a List Contains a String Element While Ignoring Case](https://www.baeldung.com/java-list-search-case-insensitive)

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

@@ -0,0 +1,15 @@
+<?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-list-6</artifactId>
+    <name>core-java-collections-list-6</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+</project>

core-java-modules/core-java-collections-list-6/src/test/java/com/baeldung/lists/StringListCaseInsensitiveContainsUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.lists;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+public class StringListCaseInsensitiveContainsUnitTest {
+    private final static List<String> THE_LIST = List.of("Game of Thrones", "Forrest Gump", "American Beauty", "Pretty Woman", "Catch Me If You Can");
+
+    @Test
+    void whenUsingContains_thenGetExpectedResult() {
+        assertFalse(THE_LIST.contains("catch me if you can"));
+    }
+
+    boolean ignoreCaseContainsForLoop(List<String> list, String value) {
+        for (String e : list) {
+            if (value.equalsIgnoreCase(e))
+                return true;
+        }
+        return false;
+    }
+
+    @Test
+    void whenUsingIgnoreCaseContainsForLoop_thenGetExpectedResult() {
+        assertTrue(ignoreCaseContainsForLoop(THE_LIST, "CATCH me if you CAN"));
+        assertTrue(ignoreCaseContainsForLoop(THE_LIST, "game of thrones"));
+        assertFalse(ignoreCaseContainsForLoop(THE_LIST, "The Godfather"));
+    }
+
+    @Test
+    void whenUsingIgnoreCaseContainsStream_thenGetExpectedResult() {
+        assertTrue(THE_LIST.stream()
+          .anyMatch(e -> e.equalsIgnoreCase("CATCH me if you CAN")));
+
+        assertTrue(THE_LIST.stream()
+          .anyMatch("game of thrones"::equalsIgnoreCase));
+
+        assertFalse(THE_LIST.stream()
+          .anyMatch("The Godfather"::equalsIgnoreCase));
+    }
+}

core-java-modules/core-java-collections-maps-6/src/test/com/baeldung/objecttomap/ObjectToMapUnitTest.java

@@ -1,76 +0,0 @@
-package java.com.baeldung.objecttomap;
-import com.google.gson.Gson;
-import org.junit.Assert;
-import org.junit.Test;
-import wiremock.com.fasterxml.jackson.core.type.TypeReference;
-import wiremock.com.fasterxml.jackson.databind.ObjectMapper;
-import wiremock.com.google.common.reflect.TypeToken;
-import java.lang.reflect.Field;
-import java.util.HashMap;
-import java.util.Map;
-
-public class ObjectToMapUnitTest {
-    Employee employee = new Employee("John", 3000.0);
-
-    @Test
-    public void givenJavaObject_whenUsingReflection_thenConvertToMap() throws IllegalAccessException {
-        Map<String, Object> map = convertUsingReflection(employee);
-        Assert.assertEquals(employee.getName(), map.get("name"));
-        Assert.assertEquals(employee.getSalary(), map.get("salary"));
-    }
-
-    private Map<String, Object> convertUsingReflection(Object object) throws IllegalAccessException {
-        Map<String, Object> map = new HashMap<>();
-        Field[] fields = object.getClass().getDeclaredFields();
-
-        for (Field field : fields) {
-            field.setAccessible(true);
-            map.put(field.getName(), field.get(object));
-        }
-
-        return map;
-    }
-
-    @Test
-    public void givenJavaObject_whenUsingJackson_thenConvertToMap() {
-        ObjectMapper objectMapper = new ObjectMapper();
-        Map<String, Object> map = objectMapper.convertValue(employee, new TypeReference<Map<String, Object>>() {});
-        Assert.assertEquals(employee.getName(), map.get("name"));
-        Assert.assertEquals(employee.getSalary(), map.get("salary"));
-    }
-
-    @Test
-    public void givenJavaObject_whenUsingGson_thenConvertToMap() {
-        Gson gson = new Gson();
-        String json = gson.toJson(employee);
-        Map<String, Object> map = gson.fromJson(json, new TypeToken<Map<String, Object>>() {}.getType());
-        Assert.assertEquals(employee.getName(), map.get("name"));
-        Assert.assertEquals(employee.getSalary(), map.get("salary"));
-    }
-
-    private static class Employee {
-        private String name;
-        private Double salary;
-
-        public Employee(String name, Double salary) {
-            this.name = name;
-            this.salary = salary;
-        }
-
-        public String getName() {
-            return name;
-        }
-
-        public void setName(String name) {
-            this.name = name;
-        }
-
-        public Double getSalary() {
-            return salary;
-        }
-
-        public void setSalary(Double age) {
-            this.salary = salary;
-        }
-    }
-}

core-java-modules/core-java-collections-maps-6/src/test/java/com/baeldung/objecttomap/ObjectToMapUnitTest.java

@@ -0,0 +1,128 @@
+package com.baeldung.objecttomap;
+
+import static org.junit.Assert.assertEquals;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.reflect.TypeToken;
+import com.google.gson.Gson;
+import org.junit.Test;
+import java.lang.reflect.Field;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
+import java.util.stream.Collectors;
+
+public class ObjectToMapUnitTest {
+    Employee employee = new Employee("John", 3000.0);
+
+    @Test
+    public void givenJavaObject_whenUsingReflection_thenConvertToMap() throws IllegalAccessException {
+        Map<String, Object> map = convertUsingReflection(employee);
+        assertEquals(employee.getName(), map.get("name"));
+        assertEquals(employee.getSalary(), map.get("salary"));
+    }
+
+    private Map<String, Object> convertUsingReflection(Object object) throws IllegalAccessException {
+        Map<String, Object> map = new HashMap<>();
+        Field[] fields = object.getClass().getDeclaredFields();
+
+        for (Field field : fields) {
+            field.setAccessible(true);
+            map.put(field.getName(), field.get(object));
+        }
+
+        return map;
+    }
+
+    @Test
+    public void givenJavaObject_whenUsingJackson_thenConvertToMap() {
+        ObjectMapper objectMapper = new ObjectMapper();
+        Map<String, Object> map = objectMapper.convertValue(employee, new TypeReference<Map<String, Object>>() {});
+        assertEquals(employee.getName(), map.get("name"));
+        assertEquals(employee.getSalary(), map.get("salary"));
+    }
+
+    @Test
+    public void givenJavaObject_whenUsingGson_thenConvertToMap() {
+        Gson gson = new Gson();
+        String json = gson.toJson(employee);
+        Map<String, Object> map = gson.fromJson(json, new TypeToken<Map<String, Object>>() {}.getType());
+        assertEquals(employee.getName(), map.get("name"));
+        assertEquals(employee.getSalary(), map.get("salary"));
+    }
+
+    @Test
+    public void given_UnsortedMap_whenSortingByValueDescending_thenValuesAreInDescendingOrder() {
+        Map<String, Integer> unsortedMap = new HashMap<>();
+        unsortedMap.put("one", 1);
+        unsortedMap.put("three", 3);
+        unsortedMap.put("five", 5);
+        unsortedMap.put("two", 2);
+        unsortedMap.put("four", 4);
+
+        Map<String, Integer> sortedMap = sortMapByValueDescending(unsortedMap);
+
+        assertEquals(5, sortedMap.size());
+        final Iterator<Integer> iterator = sortedMap.values().iterator();
+        assertEquals(5, (int) iterator.next());
+        assertEquals(4, (int) iterator.next());
+        assertEquals(3, (int) iterator.next());
+        assertEquals(2, (int) iterator.next());
+        assertEquals(1, (int) iterator.next());
+    }
+
+    @Test
+    public void given_UnsortedMap_whenUsingTreeMap_thenKeysAreInDescendingOrder() {
+        SortedMap<String, Integer> treeMap = new TreeMap<>(Comparator.reverseOrder());
+        treeMap.put("one", 1);
+        treeMap.put("three", 3);
+        treeMap.put("five", 5);
+        treeMap.put("two", 2);
+        treeMap.put("four", 4);
+
+        assertEquals(5, treeMap.size());
+        final Iterator<String> iterator = treeMap.keySet().iterator();
+        assertEquals("two", iterator.next());
+        assertEquals("three", iterator.next());
+        assertEquals("one", iterator.next());
+        assertEquals("four", iterator.next());
+        assertEquals("five", iterator.next());
+    }
+
+    private static class Employee {
+        private String name;
+        private Double salary;
+
+        public Employee(String name, Double salary) {
+            this.name = name;
+            this.salary = salary;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public Double getSalary() {
+            return salary;
+        }
+
+        public void setSalary(Double age) {
+            this.salary = salary;
+        }
+    }
+
+    public static <K, V extends Comparable<? super V>> Map<K, V> sortMapByValueDescending(Map<K, V> map) {
+        return map.entrySet().stream()
+                .sorted(Map.Entry.<K, V>comparingByValue().reversed())
+                .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new));
+    }
+}

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

@@ -3,4 +3,4 @@
 ### Relevant Articles: 
 
 - [Introduction to Javadoc](http://www.baeldung.com/javadoc)
-
+- [Code Snippets in Java API Documentation](https://www.baeldung.com/java-doc-code-snippets)

core-java-modules/core-java-documentation/src/main/java/com/baeldung/snippettag/GreetingsExternalSnippet.java

@@ -0,0 +1,18 @@
+package com.baeldung.snippettag;
+
+/**
+ * 
+ * External code snippet showing the loop process in binary search method.
+ * {@snippet class="BinarySearch" region="binary"}
+ * 
+ * Time Zone 
+ * {@snippet file="application.properties" region="zone"} 
+ *
+ */
+
+public class GreetingsExternalSnippet {
+    public void helloBinarySearch() {
+        System.out.println("Hi, it's great knowing that binary search uses a loop under the hood");
+    }
+
+}

core-java-modules/core-java-documentation/src/main/java/com/baeldung/snippettag/GreetingsHighlightTag.java

@@ -0,0 +1,35 @@
+package com.baeldung.snippettag;
+
+
+/**
+ * The code below shows a full highlighted line
+ * {@snippet :
+ * public void helloBaeldung() {
+ *     System.out.println("Hello From Team Baeldung"); // @highlight
+ * }
+ * }
+ * 
+ * highlighting a substring
+ * {@snippet :
+ * public void helloBaeldung() {
+ *     System.out.println("Hello From Team Baeldung"); // @highlight substring="println"
+ * }
+ * }
+ * 
+ * highlighting texts on multiple lines
+ * {@snippet : 
+ * public void helloBaeldung() { 
+ *     System.out.println("Hello From Team Baeldung"); // @highlight region substring="println"
+ *     String country = "USA"; 
+ *     System.out.println("Hello From Team " + country); // @end 
+ * } 
+ * }
+ * 
+ */
+
+public class GreetingsHighlightTag {
+    public void helloBaeldung() {
+        System.out.println("Hello From Team Baeldung");
+    }
+
+}

core-java-modules/core-java-documentation/src/main/java/com/baeldung/snippettag/GreetingsInlineSnippet.java

@@ -0,0 +1,17 @@
+package com.baeldung.snippettag;
+
+/**
+ * The code below shows the content of {@code helloBaeldung()} method
+ * {@snippet :
+ * public void helloBaeldung() {
+ *     System.out.println("Hello From Team Baeldung");
+ * }
+ * }
+ */
+
+public class GreetingsInlineSnippet {
+    public void helloBaeldung() {
+        System.out.println("Hello From Team Baeldung");
+    }
+
+}

core-java-modules/core-java-documentation/src/main/java/com/baeldung/snippettag/GreetingsReplaceAndLinkTag.java

@@ -0,0 +1,24 @@
+package com.baeldung.snippettag;
+
+/**
+ * 
+ * Using the replace tag
+ * {@snippet :
+ * public void helloBaeldung() {
+ *     System.out.println("Hello From Team Baeldung"); // @replace regex='".*"' replacement="..."
+ * }
+ * }
+ * Using the link tag
+ * {@snippet :
+ * public void helloBaeldung() {
+ *     System.out.println("Hello From Team Baeldung"); // @link substring="System.out" target="System#out"
+ * }
+ * }
+ *
+ */
+
+public class GreetingsReplaceAndLinkTag {
+    public void helloBaeldung() {
+        System.out.println("Hello From Team Baeldung");
+    }
+}

core-java-modules/core-java-documentation/src/main/java/snippet-files/BinarySearch.java

@@ -0,0 +1,27 @@
+
+public class BinarySearch {
+
+    public int search(int[] list, int item) {
+        int index = Integer.MAX_VALUE;
+        int low = 0;
+        int high = list.length - 1;
+        // @start region="binary"
+        while (low <= high) {
+            int mid = high - low;
+            int guess = list[mid];
+            if (guess == item) {
+                index = mid;
+                break;
+            } else if (guess > item) {
+                low = mid - 1;
+            } else {
+                low = mid + 1;
+            }
+            low++;
+        }
+        // @end region="binary"
+
+        return index;
+    }
+
+}

core-java-modules/core-java-documentation/src/main/java/snippet-files/application.properties

@@ -0,0 +1,4 @@
+# @start region="zone" 
+local.timezone = GMT+1 
+local.zip = 94123 
+# @end region="zone"

core-java-modules/core-java-io-5/.gitignore

@@ -0,0 +1,2 @@
+test-link*
+0.*

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

@@ -0,0 +1,8 @@
+## Core Java IO
+
+This module contains articles about core Java input and output (IO)
+
+### Relevant Articles: 
+
+- [[<-- Prev]](/core-java-modules/core-java-io-4)
+

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

@@ -0,0 +1,66 @@
+<?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-io-5</artifactId>
+    <name>core-java-io-5</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- Mime Type Resolution Libraries -->
+        <dependency>
+            <groupId>org.apache.tika</groupId>
+            <artifactId>tika-core</artifactId>
+            <version>${tika.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>net.sf.jmimemagic</groupId>
+            <artifactId>jmimemagic</artifactId>
+            <version>${jmime-magic.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jodd</groupId>
+            <artifactId>jodd-util</artifactId>
+            <version>${jodd-util.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.j256.simplemagic</groupId>
+            <artifactId>simplemagic</artifactId>
+            <version>${simplemagic.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-io-5</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+        <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- Mime Type Libraries -->
+        <tika.version>2.8.0</tika.version>
+        <jmime-magic.version>0.1.5</jmime-magic.version>
+        <jodd-util.version>6.2.1</jodd-util.version>
+        <simplemagic.version>1.17</simplemagic.version>
+    </properties>
+</project>

core-java-modules/core-java-io-5/src/test/java/com/baeldung/extension/ExtensionFromMimeTypeUnitTest.java

@@ -11,10 +11,8 @@ import java.util.Map;
 import java.util.Set;
 
 import org.apache.tika.mime.MimeTypeException;
-
-import org.junit.Test;
-
 import com.j256.simplemagic.ContentType;
+import org.junit.Test;
 
 public class ExtensionFromMimeTypeUnitTest {
     private static final String IMAGE_JPEG_MIME_TYPE = "image/jpeg";
@@ -37,14 +35,14 @@ public class ExtensionFromMimeTypeUnitTest {
     }
 
     @Test
-    public void whenUsingMimetypesFileTypeMap_thenGetFileExtension() {
+    public void whenUsingSimpleMagic_thenGetFileExtension() {
         List<String> expectedExtensions = Arrays.asList("jpeg", "jpg", "jpe");
         String[] detectedExtensions = ContentType.fromMimeType(IMAGE_JPEG_MIME_TYPE).getFileExtensions();
         assertThat(detectedExtensions).containsExactlyElementsOf(expectedExtensions);
     }
 
     @Test
-    public void whenUsingCustomLogic_thenGetFileExtension() {
+    public void whenUsingCustomMap_thenGetFileExtension() {
         Map<String, Set<String>> mimeExtensionsMap = new HashMap<>();
         List<String> expectedExtensions = Arrays.asList(".jpg", ".jpe", ".jpeg");
         addMimeExtensions(mimeExtensionsMap, "image/jpeg", ".jpg");

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

@@ -7,3 +7,4 @@ This module contains articles about core Java input/output(IO) APIs.
 - [Get the Desktop Path in Java](https://www.baeldung.com/java-desktop-path)
 - [Check if a File Is Empty in Java](https://www.baeldung.com/java-check-file-empty)
 - [Converting Relative to Absolute Paths in Java](https://www.baeldung.com/java-from-relative-to-absolute-paths)
+- [Detect EOF in Java](https://www.baeldung.com/java-file-detect-end-of-file)

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

@@ -43,17 +43,6 @@
             <version>${angus-activation.version}</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.jodd</groupId>
-            <artifactId>jodd-util</artifactId>
-            <version>${jodd-util.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>com.j256.simplemagic</groupId>
-            <artifactId>simplemagic</artifactId>
-            <version>${simplemagic.version}</version>
-        </dependency>
-
     </dependencies>
 
     <build>
@@ -153,8 +142,6 @@
         <fscontext.version>4.4.2</fscontext.version>
         <jakarta-activation-api.version>2.1.2</jakarta-activation-api.version>
         <angus-activation.version>2.0.1</angus-activation.version>
-        <jodd-util.version>6.2.1</jodd-util.version>
-        <simplemagic.version>1.17</simplemagic.version>
     </properties>
 
 </project>

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

@@ -18,7 +18,11 @@
             <artifactId>mapstruct</artifactId>
             <version>${mapstruct.version}</version>
         </dependency>
-
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
     </dependencies>
     <build>
         <plugins>

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/compareobjects/Address.java

@@ -0,0 +1,47 @@
+package com.baeldung.compareobjects;
+
+import java.util.Objects;
+
+public class Address {
+    private String streetAddress;
+    private String city;
+    private String postalCode;
+
+    public Address(String streetAddress, String city, String postalCode) {
+        this.streetAddress = streetAddress;
+        this.city = city;
+        this.postalCode = postalCode;
+    }
+
+    public String getStreetAddress() {
+        return streetAddress;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    public String getPostalCode() {
+        return postalCode;
+    }
+
+    @Override
+    public String toString() {
+        return "Address{" + "streetAddress='" + streetAddress + '\'' + ", city='" + city + '\'' + ", postalCode='" + postalCode + '\'' + '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Address address = (Address) o;
+        return Objects.equals(streetAddress, address.streetAddress) && Objects.equals(city, address.city) && Objects.equals(postalCode, address.postalCode);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(streetAddress, city, postalCode);
+    }
+}

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/compareobjects/Person.java

@@ -0,0 +1,58 @@
+package com.baeldung.compareobjects;
+
+import java.util.List;
+import java.util.Objects;
+
+import org.apache.commons.lang3.builder.DiffExclude;
+
+public class Person {
+    private String firstName;
+    private String lastName;
+    private int age;
+    private List<PhoneNumber> phoneNumbers;
+    @DiffExclude
+    private Address address;
+
+    public Person(String firstName, String lastName, int age, List<PhoneNumber> phoneNumbers, Address address) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.age = age;
+        this.phoneNumbers = phoneNumbers;
+        this.address = address;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public List<PhoneNumber> getPhoneNumbers() {
+        return phoneNumbers;
+    }
+
+    public Address getAddress() {
+        return address;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Person person = (Person) o;
+        return age == person.age && Objects.equals(firstName, person.firstName) && Objects.equals(lastName, person.lastName) && Objects.equals(phoneNumbers, person.phoneNumbers) && Objects.equals(address, person.address);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(firstName, lastName, age, phoneNumbers, address);
+    }
+}

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/compareobjects/PersonDiffBuilder.java

@@ -0,0 +1,32 @@
+package com.baeldung.compareobjects;
+
+import org.apache.commons.lang3.builder.DiffBuilder;
+import org.apache.commons.lang3.builder.DiffResult;
+import org.apache.commons.lang3.builder.ToStringStyle;
+
+public class PersonDiffBuilder {
+    public static DiffResult compare(Person first, Person second) {
+        DiffBuilder diffBuilder = new DiffBuilder(first, second, ToStringStyle.DEFAULT_STYLE).append("person", first.getFirstName(), second.getFirstName())
+            .append("lastName", first.getLastName(), second.getLastName())
+            .append("streetAddress", first.getAddress()
+                .getStreetAddress(), second.getAddress()
+                .getStreetAddress())
+            .append("city", first.getAddress()
+                .getCity(), second.getAddress()
+                .getCity())
+            .append("postalCode", first.getAddress()
+                .getPostalCode(), second.getAddress()
+                .getPostalCode())
+            .append("age", first.getAge(), second.getAge());
+
+        for (int i = 0; i < first.getPhoneNumbers()
+            .size(); i++) {
+            diffBuilder.append("phoneNumbers[" + i + "].number", first.getPhoneNumbers()
+                .get(i)
+                .getNumber(), second.getPhoneNumbers()
+                .get(i)
+                .getNumber());
+        }
+        return diffBuilder.build();
+    }
+}

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/compareobjects/PersonReflectionDiffBuilder.java

@@ -0,0 +1,11 @@
+package com.baeldung.compareobjects;
+
+import org.apache.commons.lang3.builder.DiffResult;
+import org.apache.commons.lang3.builder.ReflectionDiffBuilder;
+import org.apache.commons.lang3.builder.ToStringStyle;
+
+public class PersonReflectionDiffBuilder {
+    public static DiffResult compare(Person first, Person second) {
+        return new ReflectionDiffBuilder<>(first, second, ToStringStyle.SHORT_PREFIX_STYLE).build();
+    }
+}

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/compareobjects/PhoneNumber.java

@@ -0,0 +1,43 @@
+package com.baeldung.compareobjects;
+
+import java.util.Objects;
+
+import org.apache.commons.lang3.builder.DiffExclude;
+
+public class PhoneNumber {
+    private String type;
+    private String number;
+
+    public PhoneNumber(String type, String number) {
+        this.type = type;
+        this.number = number;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public String getNumber() {
+        return number;
+    }
+
+    @Override
+    public String toString() {
+        return "PhoneNumber{" + "type='" + type + '\'' + ", number='" + number + '\'' + '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        PhoneNumber that = (PhoneNumber) o;
+        return Objects.equals(number, that.number);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(number);
+    }
+}

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/compareobjects/PersonDiffBuilderUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.compareobjects;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.builder.Diff;
+import org.apache.commons.lang3.builder.DiffResult;
+import org.junit.jupiter.api.Test;
+
+public class PersonDiffBuilderUnitTest {
+
+    @Test
+    void givenTwoPeopleDifferent_whenComparingWithDiffBuilder_thenDifferencesFound() {
+        List<PhoneNumber> phoneNumbers1 = new ArrayList<>();
+        phoneNumbers1.add(new PhoneNumber("home", "123-456-7890"));
+        phoneNumbers1.add(new PhoneNumber("work", "987-654-3210"));
+
+        List<PhoneNumber> phoneNumbers2 = new ArrayList<>();
+        phoneNumbers2.add(new PhoneNumber("mobile1", "123-456-7890"));
+        phoneNumbers2.add(new PhoneNumber("mobile2", "987-654-3210"));
+
+        Address address1 = new Address("123 Main St", "London", "12345");
+        Address address2 = new Address("123 Main St", "Paris", "54321");
+
+        Person person1 = new Person("John", "Doe", 30, phoneNumbers1, address1);
+        Person person2 = new Person("Jane", "Smith", 28, phoneNumbers2, address2);
+
+        DiffResult<Person> diff = PersonDiffBuilder.compare(person1, person2);
+        for (Diff<?> d : diff.getDiffs()) {
+            System.out.println(d.getFieldName() + ": " + d.getLeft() + " != " + d.getRight());
+        }
+
+        assertFalse(diff.getDiffs()
+            .isEmpty());
+    }
+}

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/compareobjects/PersonReflectionDiffBuilderUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.compareobjects;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.builder.Diff;
+import org.apache.commons.lang3.builder.DiffResult;
+import org.junit.jupiter.api.Test;
+
+public class PersonReflectionDiffBuilderUnitTest {
+    @Test
+    void givenTwoPeopleDifferent_whenComparingWithReflectionDiffBuilder_thenDifferencesFound() {
+        List<PhoneNumber> phoneNumbers1 = new ArrayList<>();
+        phoneNumbers1.add(new PhoneNumber("home", "123-456-7890"));
+        phoneNumbers1.add(new PhoneNumber("work", "987-654-3210"));
+
+        List<PhoneNumber> phoneNumbers2 = new ArrayList<>();
+        phoneNumbers2.add(new PhoneNumber("mobile1", "123-456-7890"));
+        phoneNumbers2.add(new PhoneNumber("mobile2", "987-654-3210"));
+
+        Address address1 = new Address("123 Main St", "London", "12345");
+        Address address2 = new Address("123 Main St", "Paris", "54321");
+
+        Person person1 = new Person("John", "Doe", 30, phoneNumbers1, address1);
+        Person person2 = new Person("Jane", "Smith", 28, phoneNumbers2, address2);
+
+        DiffResult<Person> diff = PersonReflectionDiffBuilder.compare(person1, person2);
+        for (Diff<?> d : diff.getDiffs()) {
+            System.out.println(d.getFieldName() + ": " + d.getLeft() + " != " + d.getRight());
+        }
+
+        assertFalse(diff.getDiffs()
+            .isEmpty());
+    }
+}

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

@@ -4,4 +4,5 @@
 - [Integer.class vs Integer.TYPE vs int.class](https://www.baeldung.com/java-integer-class-vs-type-vs-int)
 - [Does Java Read Integers in Little Endian or Big Endian?](https://www.baeldung.com/java-integers-little-big-endian)
 - [How to Split an Integer Number Into Digits in Java](https://www.baeldung.com/java-integer-individual-digits)
+- [Java Double vs. BigDecimal](https://www.baeldung.com/java-double-vs-bigdecimal)
 - More articles: [[<-- prev]](../core-java-numbers-5)

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

@@ -25,8 +25,12 @@
             <version>${commons-codec}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
     </dependencies>
-
     <build>
         <finalName>core-java-numbers-6</finalName>
         <resources>
@@ -39,5 +43,6 @@
 
     <properties>
         <commons-codec>1.15</commons-codec>
+        <guava.version>32.1.2-jre</guava.version>
     </properties>
 </project>

core-java-modules/core-java-numbers-6/src/main/java/com/baeldung/bigintegerroot/BenchmarkRunner.java

@@ -0,0 +1,8 @@
+package com.baeldung.bigintegerroot;
+
+public class BenchmarkRunner {
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+}
+

core-java-modules/core-java-numbers-6/src/main/java/com/baeldung/bigintegerroot/BigIntegerHolder.java

@@ -0,0 +1,10 @@
+package com.baeldung.bigintegerroot;
+
+public class BigIntegerHolder {
+
+    private BigIntegerHolder() {
+    }
+    public static final String BIG_NUMBER = "179769313000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000";
+    public static final String VERY_BIG_NUMBER = "32473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834";
+    public static final String INSANELY_BIG_NUMBER = "3247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834324739274923749279342847923749237492374987230480128343247392749237492793428479237492374923749872304801283432473927492374927934284792374923749237498723048012834";
+}

core-java-modules/core-java-numbers-6/src/main/java/com/baeldung/bigintegerroot/BigIntegerSquareRootBenchmark.java

@@ -0,0 +1,60 @@
+package com.baeldung.bigintegerroot;
+
+import static com.baeldung.bigintegerroot.BigIntegerHolder.*;
+
+import com.baeldung.bigintegerroot.algorithms.Newton;
+import com.baeldung.bigintegerroot.algorithms.NewtonPlus;
+import com.google.common.math.BigIntegerMath;
+import java.math.BigInteger;
+import java.math.RoundingMode;
+import java.util.concurrent.TimeUnit;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+
+@Warmup(iterations = 1)
+@Measurement(iterations = 1, time = 1, timeUnit = TimeUnit.MINUTES)
+@Fork(1)
+@State(Scope.Benchmark)
+public class BigIntegerSquareRootBenchmark {
+
+    @Param({BIG_NUMBER, VERY_BIG_NUMBER, INSANELY_BIG_NUMBER})
+    public String number;
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void calculateRootWithJava(Blackhole blackhole) {
+        final BigInteger integer = new BigInteger(number);
+        final BigInteger root = integer.sqrt();
+        blackhole.consume(root);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void calculateRootWithGuava(Blackhole blackhole) {
+        final BigInteger integer = new BigInteger(number);
+        final BigInteger root = BigIntegerMath.sqrt(integer, RoundingMode.DOWN);
+        blackhole.consume(root);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void calculateRootWithNewtonPlus(Blackhole blackhole) {
+        final BigInteger integer = new BigInteger(number);
+        final BigInteger root = NewtonPlus.sqrt(integer);
+        blackhole.consume(root);
+    }
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void calculateRootWithNewton(Blackhole blackhole) {
+        final BigInteger integer = new BigInteger(number);
+        final BigInteger root = Newton.sqrt(integer);
+        blackhole.consume(root);
+    }
+}

core-java-modules/core-java-numbers-6/src/main/java/com/baeldung/bigintegerroot/algorithms/Newton.java

@@ -0,0 +1,29 @@
+package com.baeldung.bigintegerroot.algorithms;
+
+import java.math.BigInteger;
+
+public class Newton {
+
+    private Newton() {
+    }
+
+    public static BigInteger sqrt(BigInteger n) {
+        // Initial approximation
+        BigInteger x = n.divide(BigInteger.TWO);
+
+        // Tolerance level (small positive integer)
+        BigInteger tolerance = BigInteger.ONE;
+
+        while (true) {
+            // x_new = 0.5 * (x + n / x)
+            BigInteger xNew = x.add(n.divide(x)).divide(BigInteger.TWO);
+
+            // Check for convergence within tolerance
+            if (x.subtract(xNew).abs().compareTo(tolerance) <= 0) {
+                return xNew;
+            }
+
+            x = xNew;
+        }
+    }
+}

core-java-modules/core-java-numbers-6/src/main/java/com/baeldung/bigintegerroot/algorithms/NewtonPlus.java

@@ -0,0 +1,108 @@
+package com.baeldung.bigintegerroot.algorithms;
+
+import java.math.BigInteger;
+
+public class NewtonPlus {
+
+    private NewtonPlus() {
+    }
+
+    // A fast square root by Ryan Scott White.
+    public static BigInteger sqrt(BigInteger x) {
+        if (x.compareTo(BigInteger.valueOf(144838757784765629L)) < 0) {
+            long xAsLong = x.longValue();
+            long vInt = (long)Math.sqrt(xAsLong);
+            if (vInt * vInt > xAsLong)
+                vInt--;
+            return BigInteger.valueOf(vInt); }
+
+        double xAsDub = x.doubleValue();
+        BigInteger val;
+        if (xAsDub < 2.1267e37) // 2.12e37 largest here
+        // since sqrt(long.max*long.max) > long.max
+        {
+            long vInt = (long)Math.sqrt(xAsDub);
+            val = BigInteger.valueOf
+                ((vInt + x.divide(BigInteger.valueOf(vInt)).longValue()) >> 1);
+        }
+        else if (xAsDub < 4.3322e127) {
+            // Convert a double to a BigInteger
+            long bits = Double.doubleToLongBits(Math.sqrt(xAsDub));
+            int exp = ((int) (bits >> 52) & 0x7ff) - 1075;
+            val = BigInteger.valueOf((bits & ((1L << 52)) - 1) | (1L << 52)).shiftLeft(exp);
+
+            val = x.divide(val).add(val).shiftRight(1);
+            if (xAsDub > 2e63) {
+                val = x.divide(val).add(val).shiftRight(1); }
+        }
+        else // handle large numbers over 4.3322e127
+        {
+            int xLen = x.bitLength();
+            int wantedPrecision = ((xLen + 1) / 2);
+            int xLenMod = xLen + (xLen & 1) + 1;
+
+            //////// Do the first Sqrt on Hardware ////////
+            long tempX = x.shiftRight(xLenMod - 63).longValue();
+            double tempSqrt1 = Math.sqrt(tempX);
+            long valLong = Double.doubleToLongBits(tempSqrt1) & 0x1fffffffffffffL;
+
+            if (valLong == 0)
+                valLong = 1L << 53;
+
+            //////// Classic Newton Iterations ////////
+            val = BigInteger.valueOf(valLong).shiftLeft(53 - 1)
+                .add((x.shiftRight(xLenMod -
+                                   (3 * 53))).divide(BigInteger.valueOf(valLong)));
+
+            int size = 106;
+            for (; size < 256; size <<= 1) {
+                val = val.shiftLeft(size - 1).add(x.shiftRight
+                    (xLenMod - (3*size)).divide(val));}
+
+            if (xAsDub > 4e254) { // 4e254 = 1<<845.77
+                int numOfNewtonSteps = 31 -
+                                       Integer.numberOfLeadingZeros(wantedPrecision / size)+1;
+
+                ////// Apply Starting Size ////////
+                int wantedSize = (wantedPrecision >> numOfNewtonSteps) + 2;
+                int needToShiftBy = size - wantedSize;
+                val = val.shiftRight(needToShiftBy);
+
+                size = wantedSize;
+                do {
+                    //////// Newton Plus Iteration ////////
+                    int shiftX = xLenMod - (3 * size);
+                    BigInteger valSqrd = val.multiply(val).shiftLeft(size - 1);
+                    BigInteger valSU = x.shiftRight(shiftX).subtract(valSqrd);
+                    val = val.shiftLeft(size).add(valSU.divide(val));
+                    size *= 2;
+                } while (size < wantedPrecision);
+            }
+            val = val.shiftRight(size - wantedPrecision);
+        }
+
+        // Detect a round ups. This function can be further optimized - see article.
+        // For a ~7% speed bump the following line can be removed but round-ups will occur.
+        if (val.multiply(val).compareTo(x) > 0)
+            val = val.subtract(BigInteger.ONE);
+
+        // Enabling the below will guarantee an error is stopped for larger numbers.
+        // Note: As of this writing, there are no known errors.
+        BigInteger tmp = val.multiply(val);
+        if (tmp.compareTo(x) > 0) {
+            System.out.println("val^2(" + val.multiply(val).toString()
+                               + ") ≥ x(" + x.toString()+")");
+            System.console().readLine();
+            //throw new Exception("Sqrt function had internal error - value too high");
+        }
+        if (tmp.add(val.shiftLeft(1)).add(BigInteger.ONE).compareTo(x) <= 0) {
+            System.out.println("(val+1)^2("
+                               + val.add(BigInteger.ONE).multiply(val.add(BigInteger.ONE)).toString()
+                               + ") ≥ x(" + x.toString() + ")");
+            System.console().readLine();
+            //throw new Exception("Sqrt function had internal error - value too low");
+        }
+
+        return val;
+    }
+}

core-java-modules/core-java-numbers-6/src/test/java/com/baeldung/bigintegerroot/BigIntegerSquareRootUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.bigintegerroot;
+
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.baeldung.bigintegerroot.algorithms.Newton;
+import com.baeldung.bigintegerroot.algorithms.NewtonPlus;
+import com.google.common.math.BigIntegerMath;
+import java.math.BigInteger;
+import java.math.RoundingMode;
+import java.util.stream.Stream;
+import org.apache.commons.math3.util.Pair;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+class BigIntegerSquareRootUnitTest {
+
+    @ParameterizedTest
+    @ValueSource(strings = {
+        BigIntegerHolder.BIG_NUMBER,
+        BigIntegerHolder.VERY_BIG_NUMBER,
+        BigIntegerHolder.VERY_BIG_NUMBER
+    })
+    void squareRootTest(String number) {
+        final BigInteger bigInteger = new BigInteger(number);
+        final BigInteger javaRoot = bigInteger.sqrt();
+        final BigInteger guavaRoot = BigIntegerMath.sqrt(bigInteger, RoundingMode.DOWN);
+        final BigInteger newtonRoot = Newton.sqrt(bigInteger);
+        final BigInteger newtonPlusRoot = NewtonPlus.sqrt(bigInteger);
+
+        assertTrue(Stream.of(
+            new Pair<>(javaRoot, guavaRoot),
+            new Pair<>(guavaRoot, newtonRoot),
+            new Pair<>(newtonRoot, newtonPlusRoot)
+        ).allMatch(pair -> pair.getFirst().equals(pair.getSecond())));
+    }
+}

core-java-modules/core-java-numbers-conversions/pom.xml

@@ -18,6 +18,18 @@
             <artifactId>commons-lang3</artifactId>
             <version>${commons-lang3.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.testng</groupId>
+            <artifactId>testng</artifactId>
+            <version>RELEASE</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

core-java-modules/core-java-numbers-conversions/src/main/java/com/baeldung/floatdoubleconversions/FloatAndDoubleConversions.java

@@ -0,0 +1,15 @@
+package com.baeldung.floatdoubleconversions;
+
+public class FloatAndDoubleConversions {
+    public static void main(String args[]){
+        float vatRate = 14.432511f;
+        System.out.println("vatRate:"+vatRate);
+        Float localTaxRate = 20.12434f;
+        System.out.println("localTaxRate:"+localTaxRate);
+
+        double shootingAverage = 56.00000000000001;
+        System.out.println("shootingAverage:"+shootingAverage);
+        Double assistAverage = 81.123000000045;
+        System.out.println("assistAverage:"+assistAverage);
+    }
+}

core-java-modules/core-java-numbers-conversions/src/test/java/com/baeldung/floatdoubleconversions/FloatDoubleConversionsTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.floatdoubleconversions;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FloatDoubleConversionsTest {
+
+    @Test
+    public void whenDoubleType_thenFloatTypeSuccess(){
+        double interestRatesYearly = 13.333333333333334;
+        float interest = (float) interestRatesYearly;
+        System.out.println(interest);  //13.333333
+        Assert.assertTrue(Float.class.isInstance(interest));//true
+
+        Double monthlyRates = 2.111111111111112;
+        float rates = monthlyRates.floatValue();
+        System.out.println(rates);  //2.1111112
+        Assert.assertTrue(Float.class.isInstance(rates));//true
+    }
+    @Test
+    public void whenFloatType_thenDoubleTypeSuccess(){
+        float gradeAverage =2.05f;
+        double average = gradeAverage;
+        System.out.println(average);  //2.049999952316284
+        Assert.assertTrue(Double.class.isInstance(average));//true
+
+        Float monthlyRates = 2.1111112f;
+        Double rates = monthlyRates.doubleValue();
+        System.out.println(rates);  //2.1111112
+        Assert.assertTrue(Double.class.isInstance(rates));//true
+    }
+
+}

core-java-modules/core-java-os-2/.gitignore

@@ -0,0 +1,26 @@
+*.class
+
+0.*
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+.resourceCache
+
+# Packaged files #
+*.jar
+*.war
+*.ear
+
+# Files generated by integration tests
+*.txt
+backup-pom.xml
+/bin/
+/temp
+
+#IntelliJ specific
+.idea/
+*.iml

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

@@ -0,0 +1,7 @@
+## Core Java OS
+
+This module contains articles about working with the operating system (OS) in Java
+
+### Relevant Articles: 
+
+

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

@@ -0,0 +1,42 @@
+<?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-os</artifactId>
+    <name>core-java-os</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <build>
+        <finalName>core-java-os</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <maven.compiler.source>1.9</maven.compiler.source>
+        <maven.compiler.target>1.9</maven.compiler.target>
+    </properties>
+
+</project>

core-java-modules/core-java-os-2/src/main/java/com/baeldung/system/EnvironmentExample.java

@@ -0,0 +1,9 @@
+package com.baeldung.system;
+
+public class EnvironmentExample {
+    public void getUserName() {
+        String username = System.getenv("USERNAME");
+        System.out.println("User: " + username);
+    }
+
+}

core-java-modules/core-java-os-2/src/main/java/com/baeldung/system/PropertiesExample.java

@@ -0,0 +1,19 @@
+package com.baeldung.system;
+
+public class PropertiesExample {
+    public void getUserName() {
+        String username = System.getProperty("user.name");
+        System.out.println("User: " + username);
+    }
+
+    public void getCustomProp() {
+        String customProperty = System.getProperty("custom.prop");
+        System.out.println("Custom property: " + customProperty);
+    }
+
+    public void getCustomPropWithFallback() {
+        String customProperty = System.getProperty("non-existent-property", "default value");
+        System.out.println("Custom property: " + customProperty);
+    }
+
+}

core-java-modules/core-java-os/src/test/java/com/baeldung/system/WhenDetectingOSUnitTest.java

@@ -1,25 +0,0 @@
-package com.baeldung.system;
-
-import org.junit.Assert;
-import org.junit.Ignore;
-import org.junit.Test;
-
-@Ignore
-public class WhenDetectingOSUnitTest {
-
-    private DetectOS os = new DetectOS();
-
-    @Test
-    public void whenUsingSystemProperty_shouldReturnOS() {
-        String expected = "Windows 10";
-        String actual = os.getOperatingSystem();
-        Assert.assertEquals(expected, actual);
-    }
-
-    @Test
-    public void whenUsingSystemUtils_shouldReturnOS() {
-        String expected = "Windows 10";
-        String actual = os.getOperatingSystemSystemUtils();
-        Assert.assertEquals(expected, actual);
-    }
-}

core-java-modules/core-java-os/src/test/java/com/baeldung/system/exit/SystemExitUnitTest.java

@@ -1,64 +0,0 @@
-package com.baeldung.system.exit;
-
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Ignore;
-import org.junit.Test;
-
-import java.security.Permission;
-
-import static org.junit.Assert.assertEquals;
-
-@Ignore("This test is ignored because it tests deprecated code")
-public class SystemExitUnitTest {
-
-    private SecurityManager securityManager;
-    private SystemExitExample example;
-
-    @Before
-    public void setUp() {
-        example = new SystemExitExample();
-        securityManager = System.getSecurityManager();
-        System.setSecurityManager(new NoExitSecurityManager());
-    }
-
-    @After
-    public void tearDown() throws Exception {
-        System.setSecurityManager(securityManager);
-    }
-
-    @Test
-    public void testExit() throws Exception {
-        try {
-            example.readFile();
-        } catch (ExitException e) {
-            assertEquals("Exit status", 2, e.status);
-        }
-    }
-
-    protected static class ExitException extends SecurityException {
-
-        private static final long serialVersionUID = 1L;
-        public final int status;
-
-        public ExitException(int status) {
-            this.status = status;
-        }
-    }
-
-    private static class NoExitSecurityManager extends SecurityManager {
-        @Override
-        public void checkPermission(Permission perm) {
-        }
-
-        @Override
-        public void checkPermission(Permission perm, Object context) {
-        }
-
-        @Override
-        public void checkExit(int status) {
-            super.checkExit(status);
-            throw new ExitException(status);
-        }
-    }
-}

core-java-modules/core-java-regex-2/src/main/java/com/baeldung/alphanumeric/AlphanumericPerformanceBenchmark.java

@@ -0,0 +1,91 @@
+package com.baeldung.alphanumeric;
+
+import java.util.concurrent.TimeUnit;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+
+@Warmup(iterations = 1)
+@Measurement(iterations = 1, time = 1, timeUnit = TimeUnit.MINUTES)
+@Fork(1)
+public class AlphanumericPerformanceBenchmark {
+
+    private static final String TEST_STRING = "ABC123abc123";
+    private static final String REGEX = "[^[a-zA-Z0-9]*$]";
+    private static final Pattern PATTERN = Pattern.compile(REGEX);
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void alphanumericRegex(Blackhole blackhole) {
+        final Matcher matcher = PATTERN.matcher(TEST_STRING);
+        boolean result = matcher.matches();
+        blackhole.consume(result);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void alphanumericRegexDirectlyOnString(Blackhole blackhole) {
+        boolean result = TEST_STRING.matches(REGEX);
+        blackhole.consume(result);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void alphanumericIteration(Blackhole blackhole) {
+        boolean result = true;
+        for (int i = 0; i < TEST_STRING.length(); ++i) {
+            final int codePoint = TEST_STRING.codePointAt(i);
+            if (!isAlphanumeric(codePoint)) {
+                result = false;
+                break;
+            }
+        }
+        blackhole.consume(result);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void alphanumericIterationWithCharacterChecks(Blackhole blackhole) {
+        boolean result = true;
+        for (int i = 0; i < TEST_STRING.length(); ++i) {
+            final int codePoint = TEST_STRING.codePointAt(i);
+            if (!Character.isAlphabetic(codePoint) || !Character.isDigit(codePoint)) {
+                result = false;
+                break;
+            }
+        }
+        blackhole.consume(result);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void alphanumericIterationWithCopy(Blackhole blackhole) {
+        boolean result = true;
+        for (final char c : TEST_STRING.toCharArray()) {
+            if (!isAlphanumeric(c)) {
+                result = false;
+                break;
+            }
+        }
+        blackhole.consume(result);
+    }
+
+    @Benchmark
+    @BenchmarkMode(Mode.Throughput)
+    public void alphanumericIterationWithStream(Blackhole blackhole) {
+        boolean result = TEST_STRING.chars().allMatch(this::isAlphanumeric);
+        blackhole.consume(result);
+    }
+
+    public boolean isAlphanumeric(final int codePoint) {
+        return (codePoint >= 65 && codePoint <= 90) ||
+               (codePoint >= 97 && codePoint <= 172) ||
+               (codePoint >= 48 && codePoint <= 57);
+    }
+}

core-java-modules/core-java-regex-2/src/test/java/com/baeldung/alphanumeric/AlphanumericUnitTest.java

@@ -0,0 +1,30 @@
+package com.baeldung.alphanumeric;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class AlphanumericUnitTest {
+
+    private AlphanumericPerformanceBenchmark alphanumericPerformanceBenchmark = new AlphanumericPerformanceBenchmark();
+
+    @ParameterizedTest
+    @CsvSource({
+        "A,true",
+        "B,true",
+        "C,true",
+        "1,true",
+        "2,true",
+        "3,true",
+        "!,false",
+        "@,false",
+        "#,false",
+        "$,false",
+        "%,false"
+    })
+    void shouldCorrectlyIdentifyAlphanumericCharacterTest(char character, boolean result) {
+        boolean actual = alphanumericPerformanceBenchmark.isAlphanumeric(character);
+        assertEquals(actual, result);
+    }
+}

core-java-modules/core-java-string-algorithms-3/README.md

@@ -11,4 +11,5 @@ This module contains articles about string-related algorithms.
 - [Find the First Non Repeating Character in a String in Java](https://www.baeldung.com/java-find-the-first-non-repeating-character)
 - [Find the First Embedded Occurrence of an Integer in a Java String](https://www.baeldung.com/java-string-find-embedded-integer)
 - [Find the Most Frequent Characters in a String](https://www.baeldung.com/java-string-find-most-frequent-characters)
-- [Checking If a String Is a Repeated Substring](https://www.baeldung.com/java-repeated-substring)
+- [Checking If a String Is a Repeated Substring](https://www.baeldung.com/java-repeated-substring)
+- [Check if Letter Is Emoji With Java](https://www.baeldung.com/java-check-letter-emoji)

core-java-modules/core-java-string-operations-5/README.md

@@ -11,4 +11,3 @@
 - [Check if the First Letter of a String Is a Number](https://www.baeldung.com/java-check-if-string-starts-with-number)
 - [Print “” Quotes Around a String in Java](https://www.baeldung.com/java-string-print-quotes)
 - [Remove Punctuation From a String in Java](https://www.baeldung.com/java-remove-punctuation-from-string)
-- [Replacing Single Quote with \’ in Java String](https://www.baeldung.com/java-replacing-single-quote-string)

core-java-modules/core-java-string-operations-6/README.md

@@ -10,3 +10,5 @@
 - [Check if a String Contains Non-Alphanumeric Characters](https://www.baeldung.com/java-string-test-special-characters)
 - [Check if a String Has All Unique Characters in Java](https://www.baeldung.com/java-check-string-all-unique-chars)
 - [Performance Comparison Between Different Java String Concatenation Methods](https://www.baeldung.com/java-string-concatenation-methods)
+- [Replacing Single Quote with \’ in Java String](https://www.baeldung.com/java-replacing-single-quote-string)
+

core-java-modules/pom.xml

@@ -28,13 +28,14 @@
         <!--<module>core-java-streams-2</module> -->
         <!--<module>core-java-sun</module> -->
         <module>core-java-9-improvements</module>
-        <module>core-java-collections-array-list</module>
         <module>core-java-9-streams</module>
         <module>core-java-9</module>
         <module>core-java-10</module>
         <module>core-java-11</module>
         <module>core-java-11-2</module>
         <module>core-java-11-3</module>
+        <module>core-java-collections-array-list</module>
+        <module>core-java-collections-array-list-2</module>
         <module>core-java-collections-list-4</module>
         <module>core-java-collections-list-5</module>
         <module>core-java-collections-maps-4</module>
@@ -78,6 +79,7 @@
         <module>core-java-collections-list</module>
         <module>core-java-collections-list-2</module>
         <module>core-java-collections-list-3</module>
+        <module>core-java-collections-list-6</module>
         <module>core-java-collections-maps</module>
         <module>core-java-collections-maps-2</module>
         <module>core-java-collections-maps-3</module>
@@ -108,6 +110,7 @@
         <module>core-java-io-2</module>
         <module>core-java-io-3</module>
         <module>core-java-io-4</module>
+        <module>core-java-io-5</module>
         <module>core-java-io-apis</module>
         <module>core-java-io-apis-2</module>
         <module>core-java-io-conversions</module>

jenkins-modules/plugins/pom.xml

@@ -12,6 +12,7 @@
         <groupId>org.jenkins-ci.plugins</groupId>
         <artifactId>plugin</artifactId>
         <version>2.33</version>
+        <relativePath/>
     </parent>
 
     <dependencies>

logging-modules/log4j/README.md

@@ -4,3 +4,4 @@
 - [A Guide to Rolling File Appenders](http://www.baeldung.com/java-logging-rolling-file-appenders)
 - [Logging Exceptions Using SLF4J](https://www.baeldung.com/slf4j-log-exceptions)
 - [Log4j Warning: “No Appenders Could Be Found for Logger”](https://www.baeldung.com/log4j-no-appenders-found)
+- [A Guide to Log4j and the log4j.properties File in Java](https://www.baeldung.com/java-log4j-properties-guide)

logging-modules/log4j2/README.md

@@ -9,3 +9,4 @@
 - [Log4j 2 Plugins](https://www.baeldung.com/log4j2-plugins)
 - [Printing Thread Info in Log File Using Log4j2](https://www.baeldung.com/log4j2-print-thread-info)
 - [Log4j2 – Logging to Both File and Console](https://www.baeldung.com/java-log4j2-file-and-console)
+- [Log4j 2 Configuration Using a Properties File](https://www.baeldung.com/java-log4j2-config-with-prop-file)

messaging-modules/apache-camel/pom.xml

@@ -17,30 +17,39 @@
 
     <dependencies>
         <dependency>
-            <groupId>org.apache.camel</groupId>
-            <artifactId>camel-core</artifactId>
-            <version>${env.camel.version}</version>
+            <groupId>org.apache.camel.springboot</groupId>
+            <artifactId>camel-spring-boot-starter</artifactId>
+            <version>${camel.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.camel.springboot</groupId>
+            <artifactId>camel-jackson-starter</artifactId>
+            <version>${camel.version}</version>
         </dependency>
         <dependency>
             <groupId>org.apache.camel</groupId>
-            <artifactId>camel-spring-javaconfig</artifactId>
-            <version>${env.camel.version}</version>
+            <artifactId>camel-test-spring-junit5</artifactId>
+            <version>${camel.version}</version>
+            <scope>test</scope>
         </dependency>
         <dependency>
-            <groupId>org.apache.camel</groupId>
-            <artifactId>camel-jackson</artifactId>
-            <version>${env.camel.version}</version>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-launcher</artifactId>
+            <scope>test</scope>
         </dependency>
         <dependency>
-            <groupId>org.apache.camel</groupId>
-            <artifactId>camel-test</artifactId>
-            <version>${env.camel.version}</version>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
             <scope>test</scope>
         </dependency>
     </dependencies>
 
     <properties>
-        <env.camel.version>3.14.7</env.camel.version>
+        <camel.version>3.21.0</camel.version>
     </properties>
 
 </project>

messaging-modules/apache-camel/src/main/java/com/baeldung/camel/apache/Application.java

@@ -0,0 +1,11 @@
+package com.baeldung.camel.apache;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+}

messaging-modules/apache-camel/src/main/java/com/baeldung/camel/apache/file/FileProcessor.java

@@ -5,14 +5,17 @@ import java.util.Date;
 
 import org.apache.camel.Exchange;
 import org.apache.camel.Processor;
+import org.springframework.stereotype.Component;
 
+@Component
 public class FileProcessor implements Processor {
 
+    @Override
     public void process(Exchange exchange) throws Exception {
         String originalFileName = (String) exchange.getIn().getHeader(Exchange.FILE_NAME, String.class);
 
         Date date = new Date();
-        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH-mm-ss");
+        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
         String changedFileName = dateFormat.format(date) + originalFileName;
         exchange.getIn().setHeader(Exchange.FILE_NAME, changedFileName);
     }

messaging-modules/apache-camel/src/main/java/com/baeldung/camel/apache/file/FileRouter.java

@@ -1,7 +1,9 @@
 package com.baeldung.camel.apache.file;
 
 import org.apache.camel.builder.RouteBuilder;
+import org.springframework.stereotype.Component;
 
+@Component
 public class FileRouter extends RouteBuilder {
 
     private static final String SOURCE_FOLDER = "src/test/source-folder";

messaging-modules/apache-camel/src/main/resources/camel-context-test.xml

@@ -1,11 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
-	 http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd">
+	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	   xmlns:context="http://www.springframework.org/schema/context"
+	   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
+	 http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
 
-	<bean id="fileRouter" class="com.baeldung.camel.apache.file.FileRouter" />
-	<bean id="fileProcessor" class="com.baeldung.camel.apache.file.FileProcessor" />
+	<context:component-scan base-package="com.baeldung.camel.apache"/>
+	<context:annotation-config />
 
 	<camelContext xmlns="http://camel.apache.org/schema/spring">
 		<routeBuilder ref="fileRouter" />

messaging-modules/apache-camel/src/test/java/com/apache/baeldung/camel/jackson/FruitArrayJacksonUnmarshalUnitTest.java

@@ -1,31 +1,65 @@
 package com.apache.baeldung.camel.jackson;
 
+import com.baeldung.camel.apache.Application;
+import com.baeldung.camel.apache.jackson.Fruit;
+import org.apache.camel.Configuration;
+import org.apache.camel.EndpointInject;
+import org.apache.camel.ProducerTemplate;
+import org.apache.camel.RoutesBuilder;
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.component.jackson.ListJacksonDataFormat;
+import org.apache.camel.component.mock.MockEndpoint;
+import org.apache.camel.test.spring.junit5.CamelSpringBootTest;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.test.annotation.DirtiesContext;
+
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.List;
 
-import org.apache.camel.builder.RouteBuilder;
-import org.apache.camel.component.jackson.ListJacksonDataFormat;
-import org.apache.camel.component.mock.MockEndpoint;
-import org.apache.camel.test.junit4.CamelTestSupport;
-import org.junit.Test;
+import static org.springframework.test.util.AssertionErrors.assertEquals;
+import static org.springframework.test.util.AssertionErrors.assertNotNull;
 
-import com.baeldung.camel.apache.jackson.Fruit;
+@CamelSpringBootTest
+@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
+@SpringBootTest(classes = {Application.class, FruitArrayJacksonUnmarshalUnitTest.TestConfig.class})
+public class FruitArrayJacksonUnmarshalUnitTest {
 
-public class FruitArrayJacksonUnmarshalUnitTest extends CamelTestSupport {
+    @Autowired
+    private ProducerTemplate template;
+
+    @EndpointInject("mock:marshalledObject")
+    private MockEndpoint mock;
+
+    @Configuration
+    static class TestConfig {
+        @Bean
+        RoutesBuilder route() {
+            return new RouteBuilder() {
+                @Override
+                public void configure() throws Exception {
+                    from("direct:jsonInput").unmarshal(new ListJacksonDataFormat(Fruit.class))
+                      .to("mock:marshalledObject");
+                }
+            };
+        }
+    }
 
     @Test
     public void givenJsonFruitArray_whenUnmarshalled_thenSuccess() throws Exception {
-        MockEndpoint mock = getMockEndpoint("mock:marshalledObject");
-        mock.expectedMessageCount(1);
+        mock.setExpectedMessageCount(1);
         mock.message(0).body().isInstanceOf(List.class);
 
         String json = readJsonFromFile("/json/fruit-array.json");
         template.sendBody("direct:jsonInput", json);
-        assertMockEndpointsSatisfied();
+        mock.assertIsSatisfied();
 
         @SuppressWarnings("unchecked")
         List<Fruit> fruitList = mock.getReceivedExchanges().get(0).getIn().getBody(List.class);
@@ -41,22 +75,10 @@ public class FruitArrayJacksonUnmarshalUnitTest extends CamelTestSupport {
         assertEquals("Fruit name", "Apple", fruit.getName());
         assertEquals("Fruit id", 101, fruit.getId());
     }
-    
-    @Override
-    protected RouteBuilder createRouteBuilder() throws Exception {
-        return new RouteBuilder() {
-            @Override
-            public void configure() throws Exception {
-
-                from("direct:jsonInput").unmarshal(new ListJacksonDataFormat(Fruit.class))
-                    .to("mock:marshalledObject");
-            }
-        };
-    }
 
     private String readJsonFromFile(String path) throws URISyntaxException, IOException {
         URL resource = FruitArrayJacksonUnmarshalUnitTest.class.getResource(path);
-        return new String(Files.readAllBytes(Paths.get(resource.toURI())));
+        return new String(Files.readAllBytes(Paths.get(resource.toURI())), StandardCharsets.UTF_8);
     }
 
 }

messaging-modules/apache-camel/src/test/java/com/apache/baeldung/camel/jackson/FruitListJacksonUnmarshalUnitTest.java

@@ -1,32 +1,64 @@
 package com.apache.baeldung.camel.jackson;
 
+import com.baeldung.camel.apache.Application;
+import com.baeldung.camel.apache.jackson.Fruit;
+import com.baeldung.camel.apache.jackson.FruitList;
+import org.apache.camel.Configuration;
+import org.apache.camel.EndpointInject;
+import org.apache.camel.ProducerTemplate;
+import org.apache.camel.RoutesBuilder;
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.component.jackson.JacksonDataFormat;
+import org.apache.camel.component.mock.MockEndpoint;
+import org.apache.camel.test.spring.junit5.CamelSpringBootTest;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.List;
 
-import org.apache.camel.builder.RouteBuilder;
-import org.apache.camel.component.jackson.JacksonDataFormat;
-import org.apache.camel.component.mock.MockEndpoint;
-import org.apache.camel.test.junit4.CamelTestSupport;
-import org.junit.Test;
+import static org.springframework.test.util.AssertionErrors.assertEquals;
+import static org.springframework.test.util.AssertionErrors.assertNotNull;
 
-import com.baeldung.camel.apache.jackson.Fruit;
-import com.baeldung.camel.apache.jackson.FruitList;
+@CamelSpringBootTest
+@SpringBootTest(classes = {Application.class, FruitListJacksonUnmarshalUnitTest.TestConfig.class})
+public class FruitListJacksonUnmarshalUnitTest {
 
-public class FruitListJacksonUnmarshalUnitTest extends CamelTestSupport {
+    @Autowired
+    private ProducerTemplate template;
+
+    @EndpointInject("mock:marshalledObject")
+    private MockEndpoint mock;
+
+    @Configuration
+    static class TestConfig {
+        @Bean
+        RoutesBuilder route() {
+            return new RouteBuilder() {
+                @Override
+                public void configure() throws Exception {
+                    from("direct:jsonInput").unmarshal(new JacksonDataFormat(FruitList.class))
+                      .to("mock:marshalledObject");
+                }
+            };
+        }
+    }
 
     @Test
     public void givenJsonFruitList_whenUnmarshalled_thenSuccess() throws Exception {
-        MockEndpoint mock = getMockEndpoint("mock:marshalledObject");
-        mock.expectedMessageCount(1);
+        mock.setExpectedMessageCount(1);
         mock.message(0).body().isInstanceOf(FruitList.class);
 
         String json = readJsonFromFile("/json/fruit-list.json");
         template.sendBody("direct:jsonInput", json);
-        assertMockEndpointsSatisfied();
+        mock.assertIsSatisfied();
 
         FruitList fruitList = mock.getReceivedExchanges().get(0).getIn().getBody(FruitList.class);
         assertNotNull("Fruit lists should not be null", fruitList);
@@ -43,20 +75,9 @@ public class FruitListJacksonUnmarshalUnitTest extends CamelTestSupport {
         assertEquals("Fruit id", 101, fruit.getId());
     }
 
-    @Override
-    protected RouteBuilder createRouteBuilder() throws Exception {
-        return new RouteBuilder() {
-            @Override
-            public void configure() throws Exception {
-                from("direct:jsonInput").unmarshal(new JacksonDataFormat(FruitList.class))
-                    .to("mock:marshalledObject");
-            }
-        };
-    }
-
     private String readJsonFromFile(String path) throws URISyntaxException, IOException {
         URL resource = FruitListJacksonUnmarshalUnitTest.class.getResource(path);
-        return new String(Files.readAllBytes(Paths.get(resource.toURI())));
+        return new String(Files.readAllBytes(Paths.get(resource.toURI())), StandardCharsets.UTF_8);
     }
 
 }

messaging-modules/apache-camel/src/test/java/com/apache/camel/file/processor/FileProcessorIntegrationTest.java

@@ -1,16 +1,21 @@
 package com.apache.camel.file.processor;
 
-import java.io.File;
-
+import com.baeldung.camel.apache.file.FileProcessor;
 import org.apache.camel.CamelContext;
 import org.apache.camel.builder.RouteBuilder;
 import org.apache.camel.impl.DefaultCamelContext;
+import org.awaitility.Awaitility;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
 
-import com.baeldung.camel.apache.file.FileProcessor;
+import java.io.File;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.concurrent.TimeUnit;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
 
 
 public class FileProcessorIntegrationTest {
@@ -52,7 +57,7 @@ public class FileProcessorIntegrationTest {
     }
 
     @Test
-    public void moveFolderContentJavaDSLTest() throws Exception {
+    public void givenJavaDSLRoute_whenCamelStart_thenMoveFolderContent() throws Exception {
         final CamelContext camelContext = new DefaultCamelContext();
         camelContext.addRoutes(new RouteBuilder() {
             @Override
@@ -61,15 +66,26 @@ public class FileProcessorIntegrationTest {
             }
         });
         camelContext.start();
-        Thread.sleep(DURATION_MILIS);
+        verifyFolderContent();
         camelContext.stop();
     }
 
     @Test
-    public void moveFolderContentSpringDSLTest() throws InterruptedException {
+    public void givenSpringDSLRoute_whenCamelStart_thenMoveFolderContent() throws InterruptedException {
         ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("camel-context-test.xml");
-        Thread.sleep(DURATION_MILIS);
+        verifyFolderContent();
         applicationContext.close();
+    }
 
+    private void verifyFolderContent() {
+        Date date = new Date();
+        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
+        File destinationFile1 = new File(DESTINATION_FOLDER + "/" + dateFormat.format(date) + "File1.txt");
+        File destinationFile2 = new File(DESTINATION_FOLDER + "/" + dateFormat.format(date) + "File2.txt");
+
+        Awaitility.await().atMost(DURATION_MILIS, TimeUnit.MILLISECONDS).untilAsserted(() -> {
+            assertThat(destinationFile1.exists()).isTrue();
+            assertThat(destinationFile2.exists()).isTrue();
+        });
     }
 }

microservices-modules/micronaut/pom.xml

@@ -7,6 +7,7 @@
     <artifactId>micronaut</artifactId>
     <version>0.1</version>
     <name>micronaut</name>
+    <packaging>${packaging}</packaging>
 
     <parent>
         <groupId>com.baeldung</groupId>
@@ -18,7 +19,7 @@
         <dependencies>
             <dependency>
                 <groupId>io.micronaut</groupId>
-                <artifactId>bom</artifactId>
+                <artifactId>micronaut-bom</artifactId>
                 <version>${micronaut.version}</version>
                 <type>pom</type>
                 <scope>import</scope>
@@ -29,120 +30,136 @@
     <dependencies>
         <dependency>
             <groupId>io.micronaut</groupId>
-            <artifactId>http-client</artifactId>
+            <artifactId>micronaut-runtime</artifactId>
+            <scope>compile</scope>
+            <exclusions>
+                <exclusion>
+                    <groupId>io.micronaut</groupId>
+                    <artifactId>micronaut-jackson-databind</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut</groupId>
+            <artifactId>micronaut-http-client</artifactId>
             <scope>compile</scope>
         </dependency>
         <dependency>
             <groupId>io.micronaut</groupId>
-            <artifactId>http-server-netty</artifactId>
+            <artifactId>micronaut-http-server-netty</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>jakarta.annotation</groupId>
+            <artifactId>jakarta.annotation-api</artifactId>
             <scope>compile</scope>
         </dependency>
         <dependency>
             <groupId>io.micronaut</groupId>
-            <artifactId>inject</artifactId>
+            <artifactId>micronaut-inject</artifactId>
             <scope>compile</scope>
         </dependency>
         <dependency>
             <groupId>io.micronaut</groupId>
-            <artifactId>runtime</artifactId>
+            <artifactId>micronaut-validation</artifactId>
             <scope>compile</scope>
         </dependency>
-        <dependency>
-            <groupId>javax.annotation</groupId>
-            <artifactId>javax.annotation-api</artifactId>
-            <version>${annotation.api.version}</version>
-            <scope>compile</scope>
-        </dependency>
-        <dependency>
-            <groupId>io.micronaut</groupId>
-            <artifactId>inject-java</artifactId>
-            <scope>provided</scope>
-        </dependency>
         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
-            <version>${logback.version}</version>
             <scope>runtime</scope>
         </dependency>
         <dependency>
-            <groupId>io.projectreactor</groupId>
-            <artifactId>reactor-core</artifactId>
-            <version>${reactor.version}</version>
+            <groupId>io.micronaut.rxjava3</groupId>
+            <artifactId>micronaut-rxjava3</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut.rxjava3</groupId>
+            <artifactId>micronaut-rxjava3-http-client</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut.serde</groupId>
+            <artifactId>micronaut-serde-jackson</artifactId>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.micronaut.test</groupId>
+            <artifactId>micronaut-test-junit5</artifactId>
+            <scope>test</scope>
         </dependency>
     </dependencies>
 
     <build>
         <plugins>
+            <plugin>
+                <groupId>io.micronaut.build</groupId>
+                <artifactId>micronaut-maven-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${jdk.version}</source>
+                    <target>${jdk.version}</target>
+                    <compilerArgs>
+                        <arg>-parameters</arg>
+                    </compilerArgs>
+                    <!-- Uncomment to enable incremental compilation -->
+                    <!-- <useIncrementalCompilation>false</useIncrementalCompilation> -->
+
+                    <annotationProcessorPaths combine.self="append">
+
+                        <path>
+                            <groupId>io.micronaut</groupId>
+                            <artifactId>micronaut-inject-java</artifactId>
+                            <version>${micronaut.version}</version>
+                        </path>
+
+                        <path>
+                            <groupId>io.micronaut</groupId>
+                            <artifactId>micronaut-http-validation</artifactId>
+                            <version>${micronaut.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
+                </configuration>
+            </plugin>
+
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
                 <version>${shade.plugin.version}</version>
                 <executions>
                     <execution>
-                        <phase>package</phase>
-                        <goals>
-                            <goal>shade</goal>
-                        </goals>
-                        <configuration>
-                            <transformers>
-                                <transformer
-                                    implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-                                    <mainClass>${exec.mainClass}</mainClass>
-                                </transformer>
-                                <transformer
-                                    implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
-                            </transformers>
-                        </configuration>
+                        <id>default-shade</id>
+                        <phase>none</phase>
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>exec-maven-plugin</artifactId>
-                <configuration>
-                    <executable>java</executable>
-                    <arguments>
-                        <argument>-classpath</argument>
-                        <classpath/>
-                        <argument>${exec.mainClass}</argument>
-                    </arguments>
-                </configuration>
-            </plugin>
         </plugins>
-        <pluginManagement>
-            <plugins>
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-compiler-plugin</artifactId>
-                    <version>${compiler.plugin.version}</version>
-                    <configuration>
-                        <source>${jdk.version}</source>
-                        <target>${jdk.version}</target>
-                        <compilerArgs>
-                            <arg>-parameters</arg>
-                        </compilerArgs>
-                        <annotationProcessorPaths>
-                            <path>
-                                <groupId>io.micronaut</groupId>
-                                <artifactId>inject-java</artifactId>
-                                <version>${micronaut.version}</version>
-                            </path>
-                        </annotationProcessorPaths>
-                    </configuration>
-                </plugin>
-            </plugins>
-        </pluginManagement>
     </build>
 
     <properties>
         <!-- <exec.mainClass>com.baeldung.micronaut.helloworld.server.ServerApplication</exec.mainClass> -->
         <exec.mainClass>com.baeldung.micronaut.vs.springboot.CompareApplication</exec.mainClass>
-        <micronaut.version>1.0.0.RC2</micronaut.version>
+        <micronaut.version>3.10.1</micronaut.version>
         <jdk.version>17</jdk.version>
-        <annotation.api.version>1.3.2</annotation.api.version>
-        <reactor.version>3.1.6.RELEASE</reactor.version>
+        <release.version>17</release.version>
+        <packaging>jar</packaging>
         <compiler.plugin.version>3.7.0</compiler.plugin.version>
-        <shade.plugin.version>3.1.0</shade.plugin.version>
+        <micronaut.runtime>netty</micronaut.runtime>
+        <shade.plugin.version>3.2.0</shade.plugin.version>
     </properties>
 
 </project>

microservices-modules/micronaut/src/main/java/com/baeldung/micronaut/apiversioning/custom/client/BirdCountClient.java

@@ -0,0 +1,42 @@
+package com.baeldung.micronaut.apiversioning.custom.client;
+
+import io.micronaut.core.annotation.Nullable;
+import io.micronaut.core.async.annotation.SingleResult;
+import io.micronaut.http.HttpHeaders;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.http.annotation.Header;
+import io.micronaut.http.annotation.QueryValue;
+import io.micronaut.http.client.annotation.Client;
+import io.reactivex.rxjava3.core.Flowable;
+
+@Client("/")
+@Header(name = HttpHeaders.ACCEPT, value = "application/json")
+public interface BirdCountClient {
+
+    @Get(
+        uri = "/bird/count",
+        consumes = {"application/json"},
+        produces = {"application/json"}
+    )
+    @Header(name = "api-key", value = "11")
+    @SingleResult
+    Flowable<String> countV1(@QueryValue("max") @Nullable Integer max);
+
+    @Get(
+        uri = "/bird/count",
+        consumes = {"application/json"},
+        produces = {"application/json"}
+    )
+    @Header(name = "api-key", value = "10")
+    @SingleResult
+    Flowable<String> countV2(@QueryValue("max") @Nullable Integer max);
+
+    @Get(
+        uri = "/bird/count",
+        consumes = {"application/json"},
+        produces = {"application/json"}
+    )
+    @Header(name = "api-key", value = "")
+    @SingleResult
+    Flowable<String> countDefault(@QueryValue("max") @Nullable Integer max);
+}

microservices-modules/micronaut/src/main/java/com/baeldung/micronaut/apiversioning/custom/server/BirdCountController.java

@@ -0,0 +1,36 @@
+package com.baeldung.micronaut.apiversioning.custom.server;
+
+import io.micronaut.core.annotation.NonNull;
+import io.micronaut.core.annotation.Nullable;
+import io.micronaut.core.version.annotation.Version;
+import io.micronaut.http.annotation.Controller;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.http.annotation.QueryValue;
+import io.reactivex.rxjava3.core.Flowable;
+
+import java.util.stream.Stream;
+
+@Controller("/bird")
+public class BirdCountController {
+
+    @Get(value = "/count", produces = {"application/json"})
+    @Version("1")
+    public Flowable<String> countV1(@QueryValue("max") @Nullable Integer max) {
+        return Flowable.fromStream(
+            Stream.iterate(0, i -> i + 1)
+                .map(index -> "Bird " + index)
+                .limit(max == null ? 10 : max)
+        );
+    }
+
+    @Get(value = "/count", produces = {"application/json"})
+    @Version("2")
+    public Flowable<String> countV2(@QueryValue("max") @NonNull Integer max) {
+        return Flowable.fromStream(
+                Stream.iterate(0, i -> i + 1)
+                        .map(index -> "Bird " + index)
+                        .limit(max)
+        );
+    }
+
+}

microservices-modules/micronaut/src/main/java/com/baeldung/micronaut/apiversioning/custom/server/CustomVersionResolver.java

@@ -0,0 +1,31 @@
+package com.baeldung.micronaut.apiversioning.custom.server;
+
+import io.micronaut.context.annotation.Requires;
+import io.micronaut.context.annotation.Value;
+import io.micronaut.http.HttpRequest;
+import io.micronaut.web.router.version.resolution.RequestVersionResolver;
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+
+import java.util.Optional;
+
+@Singleton
+@Requires(property = "my.router.versioning.enabled", value = "true")
+public class CustomVersionResolver implements RequestVersionResolver {
+
+    @Inject
+    @Value("${micronaut.router.versioning.default-version}")
+    private String defaultVersion;
+
+    @Override
+    public Optional<String> resolve(HttpRequest<?> request) {
+        var apiKey = Optional.ofNullable(request.getHeaders().get("api-key"));
+
+        if (apiKey.isPresent() && !apiKey.get().isEmpty()) {
+            return Optional.of(Integer.parseInt(apiKey.get())  % 2 == 0 ? "2" : "1");
+        }
+
+        return Optional.of(defaultVersion);
+    }
+
+}

microservices-modules/micronaut/src/main/java/com/baeldung/micronaut/apiversioning/header/client/DogCountClient.java

@@ -0,0 +1,42 @@
+package com.baeldung.micronaut.apiversioning.header.client;
+
+import io.micronaut.core.annotation.Nullable;
+import io.micronaut.core.async.annotation.SingleResult;
+import io.micronaut.core.version.annotation.Version;
+import io.micronaut.http.HttpHeaders;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.http.annotation.Header;
+import io.micronaut.http.annotation.QueryValue;
+import io.micronaut.http.client.annotation.Client;
+import io.reactivex.rxjava3.core.Flowable;
+
+@Client("/")
+@Header(name = HttpHeaders.ACCEPT, value = "application/json")
+public interface DogCountClient {
+
+    @Get(
+        uri = "/dog/count",
+        consumes = {"application/json"},
+        produces = {"application/json"}
+    )
+    @Version("1")
+    @SingleResult
+    Flowable<String> countV1(@QueryValue("max") @Nullable Integer max);
+
+    @Get(
+        uri = "/dog/count",
+        consumes = {"application/json"},
+        produces = {"application/json"}
+    )
+    @Version("2")
+    @SingleResult
+    Flowable<String> countV2(@QueryValue("max") @Nullable Integer max);
+
+    @Get(
+        uri = "/dog/count",
+        consumes = {"application/json"},
+        produces = {"application/json"}
+    )
+    @SingleResult
+    Flowable<String> countDefault(@QueryValue("max") @Nullable Integer max);
+}

microservices-modules/micronaut/src/main/java/com/baeldung/micronaut/apiversioning/header/server/DogCountController.java

@@ -0,0 +1,36 @@
+package com.baeldung.micronaut.apiversioning.header.server;
+
+import io.micronaut.core.annotation.NonNull;
+import io.micronaut.core.annotation.Nullable;
+import io.micronaut.core.version.annotation.Version;
+import io.micronaut.http.annotation.Controller;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.http.annotation.QueryValue;
+import io.reactivex.rxjava3.core.Flowable;
+
+import java.util.stream.Stream;
+
+@Controller("/dog")
+public class DogCountController {
+
+    @Get(value = "/count", produces = {"application/json"})
+    @Version("1")
+    public Flowable<String> countV1(@QueryValue("max") @Nullable Integer max) {
+        return Flowable.fromStream(
+            Stream.iterate(0, i -> i + 1)
+                .map(index -> "Dog " + index)
+                .limit(max == null ? 10 : max)
+        );
+    }
+
+    @Get(value = "/count", produces = {"application/json"})
+    @Version("2")
+    public Flowable<String> countV2(@QueryValue("max") @NonNull Integer max) {
+        return Flowable.fromStream(
+                Stream.iterate(0, i -> i + 1)
+                        .map(index -> "Dog " + index)
+                        .limit(max)
+        );
+    }
+
+}

microservices-modules/micronaut/src/main/java/com/baeldung/micronaut/apiversioning/param/client/CatCountClient.java

@@ -0,0 +1,23 @@
+package com.baeldung.micronaut.apiversioning.param.client;
+
+import io.micronaut.core.annotation.Nullable;
+import io.micronaut.core.async.annotation.SingleResult;
+import io.micronaut.http.HttpHeaders;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.http.annotation.Header;
+import io.micronaut.http.annotation.QueryValue;
+import io.micronaut.http.client.annotation.Client;
+import io.reactivex.rxjava3.core.Flowable;
+
+@Client("/")
+@Header(name = HttpHeaders.ACCEPT, value = "application/json")
+public interface CatCountClient {
+
+    @Get(
+        uri = "/cat/count",
+        consumes = {"application/json"},
+        produces = {"application/json"}
+    )
+    @SingleResult
+    Flowable<String> count(@QueryValue("max") @Nullable Integer max, @QueryValue(value = "v", defaultValue = "1") @Nullable Integer version);
+}

microservices-modules/micronaut/src/main/java/com/baeldung/micronaut/apiversioning/param/server/CatCountController.java

@@ -0,0 +1,37 @@
+package com.baeldung.micronaut.apiversioning.param.server;
+
+import io.micronaut.core.annotation.NonNull;
+import io.micronaut.core.annotation.Nullable;
+import io.micronaut.core.version.annotation.Version;
+import io.micronaut.http.annotation.Controller;
+import io.micronaut.http.annotation.Get;
+import io.micronaut.http.annotation.QueryValue;
+import io.reactivex.rxjava3.core.Flowable;
+
+import java.util.stream.Stream;
+
+@Controller("/cat")
+public class CatCountController {
+
+    @Get(value = "/count", produces = {"application/json"})
+    @Version("1")
+    public Flowable<String> countV1(@QueryValue("max") @Nullable Integer max) {
+        return Flowable.fromStream(
+            Stream.iterate(0, i -> i + 1)
+                .map(index -> "Cat " + index)
+                .limit(max == null ? 10 : max)
+        );
+    }
+
+
+    @Get(value = "/count", produces = {"application/json"})
+    @Version("2")
+    public Flowable<String> countV2(@QueryValue("max") @NonNull Integer max) {
+        return Flowable.fromStream(
+                Stream.iterate(0, i -> i + 1)
+                        .map(index -> "Cat " + index)
+                        .limit(max)
+        );
+    }
+
+}