If you really want to master Java Streams, you shouldn’t split basics and advanced across two separate training blocks. Knowledge builds better in one go: what your team establishes on day one with stream pipelines, flatMap(), and collectors is immediately taken further on days two and three – with custom spliterators, groupingBy(), and the new Stream Gatherers.
In three days, this course takes your team to the full level of the Java Streams API – clearly explained, directly applicable, and cheaper than two separate bookings.
This three-day combined training merges the content of two individual courses – Java Streams Basics and Java Streams Advanced – and gives you a practical and in-depth understanding of the Java Stream API: from the basics and best practices to advanced techniques like Custom Collectors and Stream Gatherers.
You could also learn Java Streams in two separate trainings – but the combined package is more efficient: three compact days instead of four, a seamless transition from basics to advanced, and a learning arc that builds on itself without interruption.
On the first day, you’ll learn the functional programming fundamentals and the structure of stream pipelines:
All of this is directly applied in hands-on exercises – the perfect foundation for the advanced topics on days two and three.
On days two and three, the focus shifts to efficiency, extensibility, and modern techniques:
You’ll gain a deep understanding of how streams work internally – and you’ll be equipped to confidently decide when and how to use streams effectively – and when it’s better not to.
The course concludes with a comprehensive final project, where you’ll model a real-world data processing scenario using streams – from requirements through stream design to a performant solution. We’ll review your results together and discuss best practices for production-ready stream code.
👉 Just looking for the basics? Check out Java Streams Basics – Practical Fundamentals for Beginners.
👉 Only want the advanced topics? Then Java Streams Advanced – Gatherers, Spliterators & More might be the better fit.
This course is designed for Java developers who want to learn how to use the Streams API efficiently and elegantly – from the ground up – and then immediately take the next step: focusing on performance, extensibility, and modern features like gatherers or custom spliterators.
It’s ideal for anyone seeking a comprehensive knowledge of Java Streams in a short time – for example, during a technology upgrade, relaunch, or refactoring project.
Functional Programming in Java:
Consumer, Supplier, Function, Predicate, etc.)Stream Basics:
IntStream, LongStream, DoubleStreamIntermediate Operations Deep Dive:
map(), flatMap(), filter()distinct(), sorted(), limit(), skip()peek() – used correctlyTerminal Operations:
collect() – the most versatile terminal operatortoList(), toSet(), toMap()forEach(), forEachOrdered()reduce() for aggregationsfindFirst(), findAny()allMatch(), anyMatch(), noneMatch()Advanced Collectors and Reduce Operations:
reduce(): concepts and practical usepeek(): when it’s helpful and when notgroupingBy(), partitioningBy()counting(), summingInt(), averagingDouble()joining()Building Custom Collectors:
Collector interface: supplier(), accumulator(), combiner(), finisher()CONCURRENT, IDENTITY_FINISH, UNORDEREDStream Performance and Spliterator Basics:
ORDERED, SIZED, SUBSIZED, CONCURRENT, etc.Legacy Code Refactoring Workshop:
Advanced Stream Patterns and Custom Spliterators:
OptionaltryAdvance(), trySplit(), estimateSize()generate(), iterate()Stream Gatherers (since Java 22, finalized in Java 24):
Gatherer interface: integrator(), combiner(), finisher()fold(), scan(), windowFixed(), windowSliding()Integration and Architecture Patterns:
Workshop and Problem Solving:
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 Java systems, write performant code, and develop their teams sustainably.
With HappyCoders.eu, I’ve built one of the most widely read Java blogs in the German-speaking world, and I regularly speak at conferences and user groups.
My goal: to teach complex topics in a way that is understandable, practical, and immediately applicable.
Sven 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.
Anyone who understands Java can easily follow this trainer. The exercises are well thought out and focused on the essentials.
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 overall package was very coherent and always tailored to us.
Very practical and good exercise examples.
Quick to respond to questions – a very flexible trainer.
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.
The mix of knowledge, likability, and content was very pleasant.
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.
The course requires solid basic Java knowledge – ideally at least two years of practical experience. Since the first day starts with lambda expressions and functional interfaces, you don’t need to know these topics in advance. However, experience with collections and the basic Java type system is important, so we can dive straight into the stream pipeline concepts.
All participants need an up-to-date IDE with at least Java 24 – I use IntelliJ IDEA myself. Java 24 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.