A few Java 24 examples

README.md

@@ -9,6 +9,12 @@ This repository contains Java examples that are designed to track and document t
 
 ## Specifications & Practices
 
+* [Java 24](java-24/) (March, 2025)
+  * [JEP 488](java-24/src/main/java/com/ibrahimatay/JEP488PrimitiveTypesInPatternsInstanceofAndSwitch.java): Primitive Types in Patterns, instanceof, and switch
+  * [JEP 495](java-24/src/main/java/com/ibrahimatay/JEP495SimpleSourceFilesAndInstanceMainMethods.java): Simple Source Files and Instance Main Methods
+  * [JEP 485](java-24/src/main/java/com/ibrahimatay/JEP485StreamGatherers.java): Stream Gatherers
+  * [JEP 487](java-24/src/main/java/com/ibrahimatay/JEP487ScopedValues.java): Scoped Values
+
 * [Java 23](java-23/) (September, 2024)
   * [JEP 455](java-23/src/main/java/com/ibrahimatay/JEP455PrimitiveTypesInPatternsInstanceofAndSwitch.java): Primitive Types in Patterns, instanceof, and switch
   * [JEP 467](java-23/src/main/java/com/ibrahimatay/JEP467MarkdownDocumentationComments.java): Markdown Documentation Comments

java-24/pom.xml

@@ -0,0 +1,33 @@
+<?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.ibrahimatay</groupId>
+        <artifactId>Java-Features</artifactId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>java-24</artifactId>
+
+    <properties>
+        <maven.compiler.source>24</maven.compiler.source>
+        <maven.compiler.target>24</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>24</source>
+                    <target>24</target>
+                    <compilerArgs>--enable-preview</compilerArgs>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

java-24/src/main/java/JEP485StreamGatherers.java

@@ -0,0 +1,34 @@
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.stream.Gatherers;
+import java.util.stream.Stream;
+
+public class JEP485StreamGatherers {
+    public static void main(String[] args) {
+        // Stream Gatherers (JEP 485)
+        // https://openjdk.java.net/jeps/485
+
+        // Custom Intermediate Operation distinctBy
+        /*
+        Stream.of("foo", "bar", "baz", "quux")
+                .gather(Gatherers.distinctBy(String::length))
+                .toList();
+        */
+
+        // Creating Fixed-size Windows
+        /*
+        Stream.iterate(0, i -> i + 1)
+                .gather(Gatherers.windowFixed(3))
+                .limit(2)
+                .toList();
+         */
+
+        // Parallel Processing with selectOne
+        /*
+        Stream.generate(() -> ThreadLocalRandom.current().nextInt())
+                .limit(1000)
+                .parallel()
+                .gather(Gatherers.selectOne(Math::max))
+                .findFirst();
+         */
+    }
+}

java-24/src/main/java/JEP487ScopedValues.java

@@ -0,0 +1,21 @@
+import static java.lang.ScopedValue.where;
+
+public class JEP487ScopedValues {
+    // Define a scoped value
+    private static final ScopedValue<String> USER_NAME = ScopedValue.newInstance();
+
+    public static void main(String[] args) {
+        // JEP 487: Scoped Values (Fourth Preview)
+        // https://openjdk.org/jeps/487
+
+        where(USER_NAME, "John").run(() -> {
+            System.out.println("User: " + USER_NAME.get());
+            subMethod();
+        });
+    }
+
+    public static void subMethod() {
+        // Access scoped value within a sub-method
+        System.out.println("User in subMethod: " + USER_NAME.get());
+    }
+}

java-24/src/main/java/JEP488PrimitiveTypesInPatternsInstanceofAndSwitch.java

@@ -0,0 +1,61 @@
+import java.util.Map;
+
+public class JEP488PrimitiveTypesInPatternsInstanceofAndSwitch {
+    public static void main(String[] args) {
+        // JEP 488: Primitive Types in Patterns, instanceof, and switch (Second Preview)
+        // https://openjdk.org/jeps/488
+
+        // Primitive Types ile Pattern Matching
+        Object obj = 42;
+        if (obj instanceof int i) {
+            System.out.printf("Primitive int value: %1$s\n", i);
+        }
+
+        // Switch for Primitive Type
+        System.out.printf("%1$s HTTP status code refers to a %2$s%n", 100, getHTTPCodeDesc(100));
+        System.out.printf("%1$s HTTP status code refers to a %2$s%n", 200, getHTTPCodeDesc(200));
+        System.out.printf("%1$s HTTP status code refers to a %2$s%n", 403, getHTTPCodeDesc(403));
+        System.out.printf("%1$s HTTP status code refers to a %2$s%n", 0, getHTTPCodeDesc(0));
+
+        // Record Patterns with Primitive Types
+        JsonValue json = new JsonObject(Map.of(
+                "name", new JsonString("Alice"),
+                "age", new JsonNumber(28)
+        ));
+
+        if (json instanceof JsonObject(var map)
+                && map.get("name") instanceof JsonString(var name)
+                && map.get("age") instanceof JsonNumber(var age)) {
+            System.out.printf("Name: %s, Age: %.0f%n", name, age);
+        }
+    }
+
+    // Switch for Primitive Type
+    public static String getHTTPCodeDesc(int code){
+        return switch(code) {
+            case 100 -> "Continue";
+            case 200 -> "OK";
+            case 301 -> "Moved Permanently";
+            case 302 -> "Found";
+            case 400 -> "Bad Request";
+            case 500 -> "Internal Server Error";
+            case 502 -> "Bad Gateway";
+            case int i when (i > 100 && i < 200) -> "Informational";
+            case int i when (i > 200 && i < 300) -> "Successful";
+            case int i when (i > 302 && i < 400) -> "Redirection";
+            case int i when (i > 400 && i < 500) -> "Client Error";
+            case int i when (i > 502 && i < 600) -> "Server Error";
+            default -> "Unknown error";
+        };
+    }
+}
+
+interface Human {}
+class Employee implements Human {}
+class Boss implements Human {}
+
+sealed interface JsonValue permits JsonString, JsonNumber, JsonObject {}
+
+record JsonString(String value) implements JsonValue {}
+record JsonNumber(double value) implements JsonValue {}
+record JsonObject(Map<String, JsonValue> map) implements JsonValue {}

java-24/src/main/java/JEP495SimpleSourceFilesAndInstanceMainMethods.java

@@ -0,0 +1,10 @@
+// JEP 495: Simple Source Files and Instance Main Methods (Fourth Preview)
+// https://openjdk.org/jeps/495
+
+public void main() {
+    System.out.printf("%1$s + %2$s = %3$s", 1,2, sum(1,2));
+}
+
+int sum(int x, int y) {
+    return x+y;
+}

pom.xml

@@ -9,9 +9,6 @@
     <packaging>pom</packaging>
     <version>1.0-SNAPSHOT</version>
     <modules>
-        <module>java-5</module>
-        <module>java-6</module>
-        <module>java-7</module>
         <module>java-8</module>
         <module>java-9</module>
         <module>java-10</module>
@@ -23,6 +20,7 @@
         <module>java-12</module>
         <module>java-23</module>
         <module>java-14</module>
+        <module>java-24</module>
     </modules>
 
     <properties>