This textbook for training and study provides classic computer science content such as sorting algorithms, tree structures, complexity, recursion, and algorithm classes, and has been adapted for the current Java version, with brief explanations of the new features used (lambda expressions, streams, etc.). The advantage of the book is its clear focus on practical application and the implementation of algorithms in Java. It has been developed for students majoring or minoring in computer science, but is also suitable for high school students in advanced courses or IT training classes. The topics are presented in an understandable manner and illustrated with well-readable algorithms formulated in Java.