I'm Sven Woltmann — a Java expert from day one. I help Java developers and teams modernize their applications and get the most out of modern Java.

I create in-depth content on the latest Java versions and features, and I run hands-on Java trainings that help teams actually use them in production.

You'll find my tutorials on Java, architecture, algorithms, and data structures in my videos, my newsletter, and my blog HappyCoders.eu.

Java has evolved massively since Java 8 — but is your team already using the new features? I run hands-on trainings on modern Java: Java 17, 21 & 25 (individually or as combined courses), Java Streams, and virtual threads & structured concurrency.

• The latest language features — records, sealed classes, pattern matching, virtual threads, and when each one actually helps.
• Hands-on from the first session — your developers write and run code themselves, not just watch slides.
• Focused on your stack — we cover the Java versions and topics your projects really use.

What participants say:

“A deep, thorough overview of all the relevant Java features since Java 8 — and the chance to try out every one of them yourself.”

“A complex topic broken down brilliantly (virtual threads).”

“If you know Java, you can follow this trainer with ease. The exercises are well thought out and focused on the essentials.”

“Pace and depth: top. The mix of theory and practice was very pleasant.”

“Content and presentation almost flawless. What impressed me was how confidently you answered questions along the way.”

👉 Java Trainings (English)
👉 Java-Schulungen (Deutsch)

Stay up-to-date with the latest Java features with this PDF Cheat Sheet!

• Avoid lengthy research with this concise overview of all Java versions up to Java 26.
• Discover the innovative features of each new Java version, summarized on a single page.
• Impress your team with your up-to-date knowledge of the latest Java version.

👉 Download the Java Versions PDF

(Hier geht's zur deutschen Version → Java-Versionen PDF)

With this 1-page PDF cheat sheet, you'll always have the 7 most important complexity classes at a glance.

• Always choose the most efficient data structures and thus increase the performance of your applications.
• Be prepared for technical interviews and confidently present your algorithm knowledge.
• Become a sought-after problem solver and be known for systematically tackling complex problems.

👉 Download the Big O Cheat Sheet

(Hier geht's zur deutschen Version → O-Notation Cheat Sheet)

Trage dich jetzt auf die Warteliste von „Mastering Data Structures in Java“ ein, und erhalte das beste Angebot!

👉 Zur Warteliste