Exploring Modern Java: Key Language Features from Java 9 to 22 in a single program

Java has evolved significantly over the years, introducing powerful new features that enhance readability, performance, and developer productivity. In this article, we explore key language improvements from Java 9 to Java 22, including the Java Platform Module System, local variable type inference, switch expressions, text blocks, record classes, sealed types, and advanced pattern matching. Through a practical Java program, we demonstrate how these features work together to simplify coding and improve maintainability. Whether you're a seasoned developer or just starting with modern Java, this guide will help you stay up to date with the latest advancements.

import java.util.*;

// Java 16: Record Classes (JEP 395)
record Person(String name, int age) {}

// Java 17: Sealed Classes (JEP 409)
sealed interface Animal permits Dog, Cat {}
record Dog(String name) implements Animal {}
record Cat(String name) implements Animal {}

public class JavaFeaturesDemo {
    public static void main(String[] args) {
        // Java 10: Local Variable Type Inference (JEP 286)
        var message = "Hello, Java!";
        System.out.println(message);

        // Java 11: Local-Variable Syntax for Lambda Parameters (JEP 323)
        List<String> names = List.of("Alice", "Bob", "Charlie");
        names.forEach((var name) -> System.out.println("Hello, " + name));

        // Java 14: Switch Expressions and Statements (JEP 361)
        int day = 3;
        var dayType = switch (day) {
            case 1, 2, 3, 4, 5 -> "Weekday";
            case 6, 7 -> "Weekend";
            default -> "Unknown";
        };
        System.out.println("Day type: " + dayType);

        // Java 15: Text Blocks (JEP 378)
        String json = """
            {
                "name": "John",
                "age": 30
            }
            """;
        System.out.println("JSON Data: " + json);

        // Java 16: Pattern Matching with instanceof (JEP 394)
        Object obj = "Pattern Matching Example";
        if (obj instanceof String str) {
            System.out.println("String length: " + str.length());
        }

        // Java 21: Record Patterns (JEP 440) and Pattern Matching with switch (JEP 441)
        Person person = new Person("John", 25);
        switch (person) {
            case Person(var name, var age) -> System.out.println("Person: " + name + ", Age: " + age);
        }

        // Java 22: Unnamed Variables and Patterns (JEP 456)
        Person unnamedPerson = new Person("Jane", 30);
        if (unnamedPerson instanceof Person(String _, int age)) {
            System.out.println("Age: " + age);
        }
    }
}

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