eugenp · maibin · Apr 30, 2024 · Apr 20, 2024 · Apr 26, 2024 · Apr 29, 2024
diff --git a/core-java-modules/core-java-22/pom.xml b/core-java-modules/core-java-22/pom.xml
@@ -0,0 +1,35 @@
+<?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>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>core-java-22</artifactId>
+
+
+    <properties>
+        <maven.compiler.source>22</maven.compiler.source>
+        <maven.compiler.target>22</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <java.version>22</java.version>
+    </properties>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>22</source>
+                    <target>22</target>
+                    <compilerArgs>--enable-preview</compilerArgs>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>
diff --git a/...odules/core-java-22/src/main/java/com/baeldung/javafeatures/ImplicitClassDeclaration.java b/...odules/core-java-22/src/main/java/com/baeldung/javafeatures/ImplicitClassDeclaration.java
@@ -0,0 +1,8 @@
+void main() {
+    System.out.println("This is an implicitly declared class without any constructs");
+
+    int x = 165;
+    int y = 100;
+
+    System.out.println(y + x);
+}
diff --git a/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/MainApp.java b/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/MainApp.java
@@ -0,0 +1,9 @@
+package com.baeldung.javafeatures;
+
+public class MainApp {
+    public static void main(String[] args) {
+        System.out.println("Hello");
+        MultiFileExample mm = new MultiFileExample();
+        mm.ping(args[0]);
+    }
+}
diff --git a/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/MemoryAPIExample.java b/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/MemoryAPIExample.java
@@ -0,0 +1,30 @@
+package com.baeldung.javafeatures;
+
+import static java.lang.foreign.FunctionDescriptor.*;
+
+import java.lang.foreign.Arena;
+import java.lang.foreign.FunctionDescriptor;
+import java.lang.foreign.Linker;
+import java.lang.foreign.MemorySegment;
+import java.lang.foreign.SymbolLookup;
+import java.lang.foreign.ValueLayout;
+import java.lang.invoke.MethodHandle;
+
+public class MemoryAPIExample {
+public long getLengthUsingNativeMethod(String string) throws Throwable {
+    SymbolLookup stdlib = Linker.nativeLinker().defaultLookup();
+    MethodHandle strlen =
+      Linker.nativeLinker()
+        .downcallHandle(
+          stdlib.find("strlen").orElseThrow(),
+          of(ValueLayout.JAVA_LONG, ValueLayout.ADDRESS));
+
+    try (Arena offHeap = Arena.ofConfined()) {
+        MemorySegment str = offHeap.allocateFrom(string);
+
+        long len = (long) strlen.invoke(str);
+        System.out.println("Finding String length using strlen function: " + len);
+        return len;
+    }
+}
+}
diff --git a/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/MultiFileExample.java b/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/MultiFileExample.java
@@ -0,0 +1,7 @@
+package com.baeldung.javafeatures;
+
+public class MultiFileExample {
+    public void ping(String s) {
+        System.out.println("Ping from Second File " + s);
+    }
+}
diff --git a/...java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/ScopedValueExample.java b/...java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/ScopedValueExample.java
@@ -0,0 +1,40 @@
+package com.baeldung.javafeatures;
+
+import java.util.Random;
+
+public class ScopedValueExample {
+    public final static ScopedValue<User> LOGGED_IN_USER = ScopedValue.newInstance();
+
+    public void serve(Request request) {
+        User loggedInUser = authenticateUser(request);
+        ScopedValue.where(LOGGED_IN_USER, loggedInUser)
+          .run(() -> processRequest(request));
+    }
+
+    private User authenticateUser(Request request) {
+        return new User(new Random().nextInt(100), STR."User\{new Random().nextInt()}");
+    }
+
+    private void processRequest(Request request) {
+        System.out.println("Processing request :: " + ScopedValueExample.LOGGED_IN_USER.get()
+          .toString());
+    }
+}
+
+class User {
+    private int id;
+    private String userName;
+
+    public User(int id, String userName) {
+        this.id = id;
+        this.userName = userName;
+    }
+
+    public String toString() {
+        return STR."User :: \{this.id}";
+    }
+}
+
+class Request {
+
+}
diff --git a/...-modules/core-java-22/src/main/java/com/baeldung/javafeatures/StreamGatherersExample.java b/...-modules/core-java-22/src/main/java/com/baeldung/javafeatures/StreamGatherersExample.java
@@ -0,0 +1,14 @@
+package com.baeldung.javafeatures;
+
+import java.util.List;
+import java.util.stream.Gatherers;
+
+public class StreamGatherersExample {
+    public List<List<String>> gatherIntoWindows(List<String> countries) {
+        List<List<String>> windows = countries.stream()
+          .gather(Gatherers.windowSliding(3))
+          .toList();
+        return windows;
+    }
+
+}
diff --git a/...java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/UnnamedExpressions.java b/...java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/UnnamedExpressions.java
@@ -0,0 +1,62 @@
+package com.baeldung.javafeatures;
+
+import static java.lang.StringTemplate.STR;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.logging.Logger;
+
+public class UnnamedExpressions {
+    private Logger LOGGER = Logger.getLogger(String.valueOf(UnnamedExpressions.class));
+
+    public int unnamedExpressionExampleUsingException(int someNumber) {
+        int divided = 0;
+        try {
+            divided = someNumber / 0;
+        } catch (ArithmeticException _) {
+            System.err.println("Division by zero");
+        }
+        return divided;
+    }
+
+    public Object unnamedExpressionsExampleUsingSwitch(Object obj) {
+        switch (obj) {
+            case Integer _ -> System.out.println("Is an integer");
+            case Float _ -> System.out.println("Is a float");
+            case String _ -> System.out.println("Is a String");
+            default -> System.out.println("Default");
+        }
+        ;
+        return obj;
+    }
+
+    public boolean unnamedExpressionForTryWithResources() {
+        String url = "localhost";
+        String user = "user";
+        String pwd = "password";
+        try (Connection _ = DriverManager.getConnection(url, user, pwd)) {
+            LOGGER.info(STR."""
+                        DB Connection successful
+                        URL = \{url}
+                        usr = \{user}
+                        pwd = \{pwd}""");
+        } catch (SQLException e) {
+            LOGGER.warning("Exception");
+        }
+        return true;
+    }
+
+    public Map<String, List<String>> unnamedExpressionForLambda() {
+        Map<String, List<String>> map = new HashMap<>();
+        map.computeIfAbsent("v1", _ -> new ArrayList<>())
+          .add("0.1");
+        return map;
+    }
+
+}
+
diff --git a/...dules/core-java-22/src/main/java/com/baeldung/javafeatures/classfile/ClassFileDriver.java b/...dules/core-java-22/src/main/java/com/baeldung/javafeatures/classfile/ClassFileDriver.java
@@ -0,0 +1,28 @@
+package com.baeldung.javafeatures.classfile;
+
+import java.io.IOException;
+import java.lang.classfile.ClassElement;
+import java.lang.classfile.ClassFile;
+import java.lang.classfile.ClassModel;
+import java.lang.classfile.MethodModel;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class ClassFileDriver {
+    public Path updateClass() throws IOException {
+        final String PREFIX = "test_";
+        final Path PATH = Path.of("src/main/java/com/baeldung/javafeatures/classfile/ClassFileExample.class");
+        ClassFile cf = ClassFile.of();
+        ClassModel classModel = cf.parse(PATH);
+        byte[] newBytes = cf.build(classModel.thisClass().asSymbol(), classBuilder -> {
+            for (ClassElement ce : classModel) {
+                if (!(ce instanceof MethodModel mm && mm.methodName()
+                  .stringValue()
+                  .startsWith(PREFIX))) {
+                    classBuilder.with(ce);
+                }
+            }
+        });
+        return Files.write(PATH, newBytes);
+    }
+}
diff --git a/...ules/core-java-22/src/main/java/com/baeldung/javafeatures/classfile/ClassFileExample.java b/...ules/core-java-22/src/main/java/com/baeldung/javafeatures/classfile/ClassFileExample.java
@@ -0,0 +1,16 @@
+package com.baeldung.javafeatures.classfile;
+
+public class ClassFileExample {
+    public void doSomething() {
+        System.out.println("Do something here");
+    }
+
+    public void doSomething2() {
+        System.out.println("Do something here as well");
+    }
+
+    public void test_something() {
+        System.out.println("Test method");
+    }
+
+}
diff --git a/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/shapes/Circle.java b/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/shapes/Circle.java
@@ -0,0 +1,19 @@
+package com.baeldung.javafeatures.shapes;
+
+public class Circle extends Shape {
+    int sides;
+    int length;
+
+    Circle(int sides, int length) {
+        if (sides != 0 && length > 0) {
+            throw new IllegalArgumentException("Cannot form circle");
+        }
+        super(sides, length);
+    }
+
+    @Override
+    int getArea() {
+        return (int) (this.length * this.length * 3.14);
+    }
+
+}
diff --git a/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/shapes/Shape.java b/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/shapes/Shape.java
@@ -0,0 +1,12 @@
+package com.baeldung.javafeatures.shapes;
+
+public abstract class Shape {
+    private int sides;
+    private int length;
+    Shape(int sides, int length) {
+        this.sides = sides;
+        this.length = length;
+    }
+
+    abstract int getArea();
+}
diff --git a/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/shapes/Square.java b/core-java-modules/core-java-22/src/main/java/com/baeldung/javafeatures/shapes/Square.java
@@ -0,0 +1,22 @@
+package com.baeldung.javafeatures.shapes;
+
+public class Square extends Shape {
+    int sides;
+    int length;
+
+    public Square(int sides, int length) {
+        if (sides != 4 && length <= 0) {
+            throw new IllegalArgumentException("Cannot form Square");
+        }
+        super(sides, length);
+    }
+
+    @Override
+    int getArea() {
+        return 4 * length;
+    }
+
+    public String whoAmI() {
+        return "I am a square";
+    }
+}
diff --git a/...-modules/core-java-22/src/test/java/com/baeldung/javafeatures/Java22ExamplesUnitTest.java b/...-modules/core-java-22/src/test/java/com/baeldung/javafeatures/Java22ExamplesUnitTest.java
@@ -0,0 +1,38 @@
+package com.baeldung.javafeatures;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.javafeatures.classfile.ClassFileDriver;
+
+public class Java22ExamplesUnitTest {
+
+    @Test
+    public void givenJava22_whenUsingLanguagePatterns_thenReturnResult() {
+        UnnamedExpressions um = new UnnamedExpressions();
+        Assert.assertEquals(0, um.unnamedExpressionExampleUsingException(100));
+        Assert.assertEquals(123, um.unnamedExpressionsExampleUsingSwitch(123));
+        Assert.assertTrue(um.unnamedExpressionForTryWithResources());
+        Assert.assertNotNull(um.unnamedExpressionForLambda());
+    }
+
+    @Test
+    public void givenJava22_whenUsingClassFileAPI_thenReturnUpdatedClass() throws IOException {
+        ClassFileDriver classFileDriver = new ClassFileDriver();
+        Assert.assertNotNull(classFileDriver.updateClass());
+    }
+
+    @Test
+    public void givenJava22_whenUsingForeignAPI_thenReturnLengthUsingCFunction() throws Throwable {
+        MemoryAPIExample mp = new MemoryAPIExample();
+        Assert.assertEquals(11, mp.getLengthUsingNativeMethod("Hello world"));
+    }
+
+    @Test
+    public void givenJava22_whenUsingStreamGatherer_thenReturnCustomList() {
+        Assert.assertNotNull(new StreamGatherersExample().gatherIntoWindows(List.of("India", "Poland", "UK", "Australia", "USA", "Netherlands")));
+    }
+}
diff --git a/core-java-modules/pom.xml b/core-java-modules/pom.xml
@@ -228,6 +228,7 @@
         <module>java-spi</module>
         <module>java-websocket</module>
         <module>core-java-8-datetime-3</module>
+        <!--<module>core-java-22</module>--> <!-- requires JDK 22 -->
     </modules>
 
     <dependencies>