In this 4-day intensive training, you’ll explore the key innovations from Java 18 through 25 – compactly presented, clearly explained, and focused on practical value in everyday development.
Start with core features from Java 18 to 21: Record Patterns, Pattern Matching for switch, and the Sequenced Collections API help you write cleaner and more maintainable code.
You’ll also cover practical API enhancements (e.g., in String, Character, and Math), the Simple Web Server API, and changes in HashMap.
The module also includes improvements in Garbage Collection (such as Generational ZGC) and lower-level optimizations like alternative locking techniques.
In the second half, you'll dive into cutting-edge features like Unnamed Variables & Patterns, Stream Gatherers, Scoped Values, and Markdown Documentation Comments – ideal for writing clean, well-documented, and context-aware code.
You’ll also explore the Foreign Function & Memory API for secure access to native libraries.
Other topics include Compact Source Files, the Instance Main Method, and performance upgrades like Compact Object Headers and Ahead-of-Time Class Loading.
With plenty of hands-on exercises inspired by real projects, you’ll learn how to apply new features directly and effectively in your daily work.
We wrap up with a look ahead to innovations such as Primitive Types in Patterns, Stable Values, a refined Structured Concurrency API, and the evolution of the Vector API.
This course is for Java developers who want to deepen their knowledge of Java 21 and 25 – structured, clear, and highly practical.
Whether you’re transitioning to Java 21 or 25 or already working with one of them: You’ll learn how to leverage modern language features, new APIs, and performance improvements efficiently.
It’s also ideal for teams already using Java 21 who want to systematically upgrade to Java 25.
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:
Additional Features:
Bugfixes:
API Enhancements:
Garbage Collection:
Performance:
Deprecations & Removals:
Major Features:
Other New Features:
API Enhancements:
Garbage Collection:
Performance / Memory Footprint:
Deprecations & Removals:
Looking Ahead:
I’m a Java expert with over 20 years of experience – as a developer, architect, CTO, performance coach, and trainer.
I’ve designed enterprise-scale systems for companies like 1&1, IONOS, and ICE Services, modernized legacy apps, and helped teams build robust, maintainable, and high-performance Java software.
With HappyCoders.eu, I’ve built one of the most widely read Java blogs in the German-speaking world. I speak at conferences and Java User Groups – and often receive praise for making complex technical topics easy to understand.
What you’ll get from my courses:
I don’t just teach features – I show you how to develop better software with a deep understanding of Java.