Java in 2025: New Features and Practical Examples

Java in 2025: What's New? A Practical Overview

Java continues to actively evolve, and 2025 is no exception. The JDK 23 and 24 releases brought long-awaited stabilizations of experimental features, as well as several completely new capabilities that fundamentally change the approach to writing code. In this article, we will break down the key innovations with practical examples so you can immediately apply them in your projects. We will cover virtual threads (Project Loom), improved Pattern Matching, new Record and Sealed Classes features, as well as API changes.

1. Virtual Threads (Project Loom) — The De Facto Standard

Virtual threads, which became stable in JDK 21, have turned into the primary tool for high-load server applications in 2025. They allow you to create millions of lightweight threads without burdening the operating system. The main advantage is simplicity: the code looks synchronous but runs asynchronously.

Example: High-Load HTTP Client

Suppose you need to send 10,000 HTTP requests. With classic threads, this would cause an OutOfMemoryError or huge overhead. With virtual threads, the task is solved elegantly:

import java.net.http.HttpClient;import java.net.http.HttpRequest;import java.net.http.HttpResponse;import java.net.URI;import java.util.concurrent.Executors;import java.util.stream.IntStream;

public class VirtualThreadsExample {    public static void main(String[] args) throws Exception {        var client = HttpClient.newHttpClient();

        try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {            IntStream.range(0, 10_000).forEach(i -> {                executor.submit(() -> {                    var request = HttpRequest.newBuilder()                            .uri(URI.create("https://httpbin.org/delay/1"))                            .build();                    try {                        var response = client.send(request, HttpResponse.BodyHandlers.ofString());                        System.out.println("Request " + i + " completed, status: " + response.statusCode());                    } catch (Exception e) {                        System.err.println("Error: " + e.getMessage());                    }                });            });        } // executor.close() waits for all threads to complete    }}

What changed in 2025? Improved integration with sockets and databases. Virtual threads now work correctly with most popular JDBC drivers (e.g., PostgreSQL) without requiring modifications. It is also now possible to set custom schedulers (ForkJoinPool) for fine-tuning performance.

2. Pattern Matching — Final Version and New Patterns

Pattern Matching for switch and instanceof has reached full maturity in 2025. The main innovation is support for record patterns and guarded patterns (conditional patterns). This allows writing very concise and safe code for parsing complex data structures.

Example: Parsing a JSON-like Structure

sealed interface Shape permits Circle, Rectangle, Triangle {}record Circle(double radius) implements Shape {}record Rectangle(double width, double height) implements Shape {}record Triangle(double base, double height) implements Shape {}

public class PatternMatchingExample {    public static double calculateArea(Shape shape) {        return switch (shape) {            case Circle c -> Math.PI * c.radius() * c.radius();            case Rectangle r -> r.width() * r.height();            // Guarded pattern: check that the triangle is not degenerate            case Triangle t when t.base() > 0 && t.height() > 0 -> 0.5 * t.base() * t.height()