The “No More Thread Leaks” Update: Java’s Structured Concurrency (JEP 525) If you’ve ever written concurrent Java code using ExecutorService, you know it can feel like herding cats. If one task fails, the others just keep running in the background like zombies, eating up resources and making debugging a nightmare. Structured Concurrency is here to fix that. It treats a group of related tasks as a single unit of work. If the main task is cancelled or fails, all its sub-tasks are automatically shut down. No leaks, no orphans, no headaches. ...

If you have ever had to read a private key or a certificate from a file in Java, you know the pain. You probably wrote a utility method that manually stripped out the —–BEGIN… header, removed newlines, and performed a Base64 decode, only to feed it into a KeyFactory. It felt like hacky string manipulation for something that should be standard. The Gist: This JEP, and its predecessor JEP 470 in Java 25, introduces a standardized, easy-to-use API for encoding and decoding PEM (Privacy-Enhanced Mail) files. Instead of using third-party libraries (like Bouncy Castle) or writing brittle string replacement code, you can now parse keys and certificates natively. ...

If you run Java in production, you are likely using the G1 (“Garbage First”) Garbage Collector (it’s the default, after all). In Java 26, G1 is getting a significant “free” performance boost—estimated at 5–15% better throughput—without you changing a single line of code. This is one of those JEPs that does its work silently in the background (literally), but it’s implications are so significant that it deserves a blog post. ...

If you’ve been waiting for Java to catch up with the modern web, the wait is over. Java 26 updates the java.net.http.HttpClient (the one we’ve loved since JDK 11) to officially support HTTP/3. Here is an example of how to use the API 1 2 3 4 5 6 7 var client = HttpClient.newHttpClient(); var request = HttpRequest.newBuilder(URI.create("https://openjdk.org/")) .GET() .build(); var response = client.send(request, HttpResponse.BodyHandlers.ofString()); assert response.statusCode() == 200; String htmlText = response.body(); Why should you care? HTTP/3 isn’t just a version bump; it swaps out TCP for QUIC (built on UDP). This is a big deal for performance because it solves “head-of-line blocking”—where one lost packet holds up the entire line of data. It basically means faster handshakes and much more reliable connections, especially if your users are on flaky networks with high packet loss. ...

JEP 516: Having Your Cake (Fast Startup) and Eating It Too (Low Latency) I have become a greater fan of Project Leyden with every deliverable it produced. I admit, I was sceptical when Chief Language Architect Brian Goetz announced Project Leyden. It felt as if some answer was needed after the arrival of GraalVM and its native images, that had a blistering startup speed. But how could we ever increase the startup of the JVM? Turns out, there are quite of few possibilities. ...

Goodbye, Applets! (For Real This Time) If you’ve been doing Java for a while, you probably remember the “good old days” of running Java in the browser. One day, I was visiting London, from Amsterdam, and I bought my first Java book. This was in de the days before you buy anything at Amazon. The book introduced me to applets for the first time. Must have been around the time of Java 1.2, so we’re talking about 1998. Fast forward to a few years later and I had a girlfriend who was studying in IT. One of her assigments was to create a functioning chess application, running in a browser via an applet. Did we have fun writing that applet. Or least, I had fun. Well, those days of Applet-Chess are over, JEP 504 in Java 26 is finally cleaning house by permanently removing the Applet API. ...

When you have been writing Java for a while, you may have noticed that you are writing final a lot. You typically use it when defining class or instance variables. In those situations the compiler will ensure that you assigned a value to it before the class constructor completes. Or you could use it with parameters to indicate that the values of these parameters should not be tinkered with. It is Java’s version of defining a constant. Or at least, that is what we have been thinking. But in real life, a final variable can be changed. Take a look at the following example: ...

We’ve only just seen the release of Java 25, the latest LTS version of the popular language. But on March, 17st, the next iteration of the Java language, Java 26, will be launched. What is in there? Java 26 will be made up of 10 Java Enhancement Proposals. Here is a short summary. In the coming weeks, I will talk about each of these in more detail on this site. ...