I am a passionate Java programmer focusing on scalable enterprise applications, optimization of algorithms, clean code, and clean architecture.

I work as an independent developer, trainer, speaker, and course instructor.

I share my knowledge about Java, architecture, algorithms, and data structures invideos, mynewsletter, and my blogHappyCoders.eu.

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

• Avoid lengthy research with thisconcise overview of all Java versions up to Java 23.
• 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 this1-page PDF cheat sheet, you'll always have the7 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 dieWarteliste von „Mastering Data Structures in Java“ ein, und erhalte das beste Angebot!

👉Zur Warteliste

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1. pathfindingpathfindingPublic

   Source code for the HappyCoders.eu articles on pathfinding and shortest path algorithms (Dijkstra, A*, Bellman-Ford, Floyd-Warshall).

   Java 39 23

2. sorting-algorithms-ultimate-guidesorting-algorithms-ultimate-guidePublic

   Sorting algorithm source codes + ultimate test to compare the performance of all algorithms. For my HappyCoders.eu article.

   Java 21 9

3. binary-treebinary-treePublic

   Source Code for HappyCoders.eu article series on tree data structures (binary tree, binary search tree, AVL tree, red-black tree).

   Java 35 22

4. o-notation-and-time-complexityo-notation-and-time-complexityPublic

   Code examples demonstrating the complexity classes O(1), O(log n), O(n), O(n log n), O(n²).

   Java 15 7

5. color-thief-javacolor-thief-javaPublic

   Grabs the dominant color or a representative color palette from an image. A very fast Java port of Lokesh Dhakar's JavaScript version.

   Java 232 41

6. hexagonal-architecture-javahexagonal-architecture-javaPublic

   This repository contains a sample Java REST application implemented according to hexagonal architecture.

   Java 130 44