Level Up Your Java: A Look at the Exciting New Features in Java 21

Java 21, released in September 2023, brings a wave of enhancements for developers of all experience levels. Whether you're a seasoned Java veteran or just starting your coding journey, this update offers a toolbox of new features to streamline your development process and make your code more efficient and expressive. Let's dive into some of the most notable additions!

1. Virtual Threads: Embrace Lightweight Concurrency

Java 21 introduces virtual threads, a game-changer for developers working with highly concurrent applications. Unlike traditional Java threads, which map directly to operating system threads, virtual threads are lightweight units of execution managed by the JVM itself. This translates to significant benefits:

• Improved Scalability: Virtual threads are much cheaper to create and manage compared to OS threads. This allows your application to handle a much larger number of concurrent tasks without compromising performance.

• Simplified Development: The API for virtual threads closely mirrors the existing java.lang.Thread API, making the transition for developers familiar with traditional threads seamless.

Here's a code snippet demonstrating how to create a simple virtual thread using the ForkJoinPool.ofVirtual method:

Java

ForkJoinPool pool = ForkJoinPool.ofVirtual();
pool.submit(() -> System.out.println("Hello from a virtual thread!"));
pool.shutdown();

2. Record Patterns: Deconstruct with Elegance

Java 21 enhances pattern matching with the introduction of record patterns. These patterns offer a concise and declarative way to deconstruct record values. This can significantly improve code readability, especially when working with complex record structures.

Consider the following example:

Java

record Person(String name, int age) {}

void greet(Person person) {
  if (person instanceof Person p) {
    System.out.println("Hello, " + p.name() + "!");
  }
}

With record patterns, we can achieve the same functionality with improved readability:

Java

void greet(Person person) {
  if (person instanceof Person record) {
    System.out.println("Hello, " + record.name() + "!");
  }
}

3. Sequenced Collections: Simplify Ordered Access

Java 21 introduces new interfaces – SequencedSet, SequencedCollection, and SequencedMap – that provide convenient methods for accessing the first and last elements of a collection. This eliminates the need for cumbersome workarounds and improves code clarity when dealing with ordered data structures.

For instance, to access the first element of a List:

List<String> names = List.of("Alice", "Bob", "Charlie");
String firstElement = names.get(0); // Pre-Java 21 approach

With sequenced collections:

List<String> names = List.of("Alice", "Bob", "Charlie");
String firstElement = names.first(); // Java 21 approach (using SequencedCollection)

4. String Templates: Enhance Readability (Preview Feature)

Java 21 introduces string templates (preview feature) as a more concise and readable alternative for string concatenation. String templates allow you to embed expressions directly within string literals using ${expression} syntax.

Here's an example:

String greeting = "Hello, " + name + "!"; // Pre-Java 21 approach

String greeting = String.format("Hello, %s!", name); // Traditional formatting

String greeting = f"Hello, {name}!"; // Java 21 string template (preview feature)

Embrace the Future of Java

Java 21 offers a compelling set of features for developers of all backgrounds. From lightweight concurrency with virtual threads to improved code readability with record patterns and sequenced collections, this update empowers you to write more efficient and expressive Java code. So, dive into these new features, explore the potential they offer, and elevate your Java development experience!

Note: This article covered a selection of the new features in Java 21. Be sure to explore the official documentation for a comprehensive list and detailed explanations.

Happy coding !