Java 25 is the new LTS version – and brings the most exciting new features since Java 21: finalized Stream Gatherers, Unnamed Variables & Patterns, and a stable Foreign Function & Memory API. For teams that base their Java upgrades on LTS versions, now is the right time.
In two days, this course brings your team up to the level Java 25 makes possible – clearly explained and immediately applicable.
In this two-day course, you’ll learn all the key enhancements introduced in Java versions 22 through 25 – compact, in-depth, and focused on practical use in real-world projects.
We’ll take a close look at modern language features like Unnamed Variables & Patterns, which improve code readability, and the new Foreign Function & Memory API, enabling secure and efficient access to native libraries. You’ll discover how to use Scoped Values for thread-safe context propagation and how Markdown Documentation Comments help you write more structured, readable documentation.
One of the highlights is the new Stream Gatherers API, which significantly simplifies complex stream aggregations. You’ll also learn how Compact Source Files and the new Instance Main Method make it easier to start new projects quickly.
Of course, we’ll also cover numerous API enhancements and important under-the-hood performance improvements, including how to synchronize virtual threads without pinning – a major step toward building highly scalable applications.
In hands-on exercises, you’ll directly apply the new features and gain a deep understanding of how to use them effectively in your projects.
At the end of the course, you’ll get a preview of what’s coming next – including Primitive Types in Patterns, instanceof, and switch, Lazy Constants (formerly Stable Values), the Vector API, and a redesigned Structured Concurrency API.
You’ll find a complete overview of all features in my Java 25 features article.
This course is designed for Java developers who want to stay ahead of the curve – with a clear, practical, and well-structured approach.
Whether you’re upgrading from Java 17 or already working with Java 21 – Java 25, the new LTS version, is the ideal time to bring your team up to date. This course gives you the knowledge to make the switch safely and productively.
If you want to tackle Java 21 and 25 together, you’ll find the right combined course here.
We won’t follow the listed order strictly. Instead, we’ll alternate between major features, smaller topics, and theory – keeping the course engaging and balanced, and helping you better retain the material.
Major Features:
Other New Features:
LocaleAPI Enhancements:
Locale-dependent list patternsDuration until another InstantGarbage Collection:
Performance / Memory Footprint:
LM_LEGACY to LM_LIGHTWEIGHTJava Flight Recorder:
Deprecations & Removals:
Thread.countStackFrames()sun.misc.UnsafeThread.suspend(), resume() and ThreadGroup.suspend(), resume(), stop()Looking Ahead:
The agenda isn’t set in stone: we can align the focus, date, and format with your team.
Request now – no obligationI’ve been working with Java for 30 years – as a developer, CTO, trainer, author, and speaker.
In that time, I’ve helped companies modernize complex systems, write performant code, and develop their teams.
With HappyCoders.eu, I’ve built one of the most widely read Java blogs in the German-speaking world – thousands of developers read my articles on the Java 25 features every day.
My goal: to teach complex topics in a way that is understandable, practical, and immediately applicable.
100 % of the participants who answered would recommend my training – 82 % without reservation.
More about meSven Woltmann of HappyCoders visited us to test and understand the new features around Java 25 together.
For two days, we worked intensively on Unnamed Variables & Patterns, Stream Gatherers, Scoped Values, the Foreign Function & Memory API, and performance topics such as virtual threads without pinning.
A big thank you to Sven for the excellent preparation, the clear didactics, and the deep technical expertise. That was a training exactly to our taste.
Content and presentation nearly flawless. I enjoyed listening throughout, learned new things, and had fun doing it.
Your confidence in answering questions along the way was impressive.
I found the trainer easy to listen to, and it never got boring. I understood the explanations well. Sven answered questions quickly and corrected errors in the worksheets on the spot.
A comprehensive training, with a trainer who knows what he is talking about. And when he doesn’t know, he looks it up right away or follows up with the answer shortly after.
Anyone who understands Java can easily follow this training. The exercises are well thought out and focused on the essentials.
A knowledgeable trainer. Good structure, practical examples. Compact, and the concepts get explained. Good, comprehensible exercises.
The overall package was very coherent and always tailored to us.
A good, in-depth overview of all relevant Java features since Java 8, and the opportunity to try all of these features out yourself.
The talk was broken up by fitting exercises. Good presentation. Our questions were taken up.
Very practical and good exercise examples.
Quick to respond to questions – a very flexible trainer.
A compact overview of how Java has evolved. A lot of input, much of which you can apply directly.
Very good repo with explanations + exercises in one place.
Pace + depth: top-notch. A very pleasant mix of theory and practice.
A complex topic broken down superbly.
All the important news from Java 9–25 was well explained.
This training can only be booked for teams. If you’d like to attend as an individual, I offer two courses (in German) through ppedv:
Both are possible: I can come to your company for an on-site training – anywhere in Germany, Austria, and Switzerland – or we run the training online, usually via Zoom.
I recommend a maximum of 12 participants per training – that way I can give everyone individual attention. There is no minimum: I charge per training, not per person.
The easiest way is the request form or an email to training@happycoders.eu. Right after submitting, you can book a video call via Calendly, where we discuss the details. You’ll then receive a concrete offer from me.
Ideally, you’re familiar with Java 21. If you’ve worked with Java 17, you’ll be fine too – the most important differences are put into context during the course. In general, I recommend at least two years of practical Java experience.
All participants need an up-to-date IDE with at least Java 25 – I use IntelliJ IDEA myself. Java 25 or later should also be installed in the terminal, as we’ll run some of the exercises there.
A training day consists of four 90-minute modules – six hours of net training time in total. Each module alternates between theory and practice two to three times, so you apply what you’ve just learned directly to code. There’s a short break between the first and second and between the third and fourth module, and a longer lunch break between modules two and three. We align the exact schedule with your working hours – that’s flexible.
About half theory, half practice: a short theory phase is followed directly by applying it to code – with examples from real projects. Listening alone doesn’t help much; the knowledge has to be used immediately for it to stick.
Yes – shortening topics, weighting them differently, changing the order, or combining content from different courses: I’m happy to adapt the agenda to your team. Since that means reworking the training materials, it involves extra effort – I’ll prepare an individual offer for you.
We usually use Zoom. If you prefer your own platform – for example, Microsoft Teams or Google Meet – I’m happy to work with that. Just let me know in advance.
Yes. Before the training, you’ll receive the exercises as a Git repository so you can get started right away. After the training, you’ll also receive the slides – including all solutions to the exercises.
Yes. All participants receive a certificate of attendance after the training.
Travel expenses are charged as a flat rate – depending on the training location and the number of overnight stays required. The exact amount is part of the individual offer I’ll send you.
Yes. For multiple booked trainings or follow-up bookings, I can offer a volume discount. We’ll discuss this in the video call, and I’ll include it in the offer.
Just write to me – I usually reply within one business day.
Or book a free video call right away, and we’ll discuss everything important.