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Java Annotated Monthly – September 2025

This month’s Java Annotated Monthly comes with a fresh mix of Java, Kotlin, AI, and tech news, plus a look at some great events you won’t want to miss. We’ve also got a featured section by Marit van Dijk, covering the new Java 25 release, the latest IntelliJ IDEA updates, and a playful take on learning modern Java.

Let’s go! 

Featured Content

Marit van Dijk

Marit van Dijk is a software developer, Java Champion and Developer Advocate at JetBrains. She has over 20 years of diverse experience across various roles and companies, and is passionate about building awesome software in collaboration with amazing people, and making developers’ lives better. She is a frequent speaker at international conferences, writes blog posts and tutorials, creates videos, and is a contributor to the book “97 Things Every Java Programmer Should Know” (O’Reilly Media).

Welcome to Java Annotated Monthly for September. For the folks in Europe / the Northern hemisphere, I hope that you have had a great summer and were able to disconnect from work.

This month, I’m excited for the start of the conference season with my first talk at JavaZone and, of course, the release of Java 25 on September 16, 2025. This release comes with some nice changes to the language: Compact Source Files and Instance Main Methods and Module Import Declarations make it easier to get started with Java, Flexible Constructor Bodies allow statements in a constructor before calling super(), so you can validate your data before constructing objects, and Scoped Values make managing thread-local data more convenient, safe, and scalable. This feature will be even more useful with Structured Concurrency (still in preview). In addition, there are improvements in performance and performance insights, as well as several other changes. We will write a blog post with more details later this month.

Java 25 support was introduced in IntelliJ IDEA 2025.2, with additional support added in 2025.2.1. IntelliJ IDEA already introduced support for Java 25 in 2025.2, and additional support was added in 2025.2.1. In case you missed it, check out the What’s New in IntelliJ IDEA 2025.2 stream, where we show you Java 25 support, Virtual Threads Debugger, Spring Debugger and Spring Modulith support, support for Maven 4 (which may also be released soon), and a sneak peek of a new feature we are working on!

Java 25 will be an “LTS” version. Or is it? If you are updating from Java 21, watch this great video by Nikolai Parlog on How to Upgrade to Java 25, showing you some of the problems you might encounter when upgrading and how to solve them, the overview of All New Java Language Features Since Java 21 by José Paumard, and other videos in the series.

In Learning Modern Java the Playful Way, fellow Java Champion Piotr Przybył and I show you how to upgrade your code using live demos (and silly jokes). You can catch a slightly updated version of this talk at several conferences this Fall/Autumn. To find out where I’ll be, check my website. If you happen to be at any of these events, please come say hi!

Java News

Do not miss the latest Java news: 

Java Tutorials and Tips

Learn more about where Java is heading and how to make the most of its latest features:

Kotlin Corner

Check out this section for everything Kotlin, from fresh updates to handy tips and tricks: 

AI

Stay in the loop with the latest AI news and insights you won’t want to miss: 

Languages, Frameworks, Libraries, and Technologies

Explore other technologies and frameworks that help boost productivity and make everyday development smoother:

Conferences and Events

Visit the coolest events of the month, both offline and online:

Culture and Community

Find articles on developer life, career growth, and the lighter side of working in tech:

And Finally…

Check out IntelliJ IDEA’s latest content picks for tips, updates, and inspiration:

That’s it for today! We’re always collecting ideas for the next Java Annotated Monthly – send us your suggestions via email or X by September 20. Don’t forget to check out our archive of past JAM issues for any articles you might have missed!

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