Top 10 Java 21 Best Practices with Complete Examples

Java 21 introduces powerful new features that improve performance, readability, and concurrency management. These updates help developers write better and more efficient code.

In this article, we will explore 10 best practices in Java 21 and provide complete examples to help you understand them better.

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1️⃣ Use Virtual Threads for High-Performance Concurrency

Why?

Traditional threads in Java are heavyweight because they map directly to OS threads. Virtual Threads in Java 21 are lightweight, enabling the JVM to manage millions of threads efficiently.

✅ Best Practice: Use Virtual Threads when handling many concurrent tasks, such as handling HTTP requests or database queries.

🔹 Complete Example: Virtual Threads in Action

import java.util.concurrent.Executors;

public class VirtualThreadExample {
    public static void main(String[] args) {
        try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
            for (int i = 0; i < 5; i++) {
                executor.submit(() -> {
                    System.out.println("Executing: " + Thread.currentThread());
                });
            }
        } // Executor closes automatically
    }
}