The book is dedicated to the Java language, which is currently one of the most popular programming languages. It is a professional language that allows you to create complex and effective programs. The book covers all the main topics that form the paradigm of the Java programming language. Among them, in particular, basic techniques of creating programs, basic operators and data types, control instructions, classes and objects, inheritance, overloading and overriding methods, interfaces (including functional), lambda expressions, error handling, thread creation, generalized types, work with files, methods of creating programs with a graphical interface. Theoretical material is presented in a simple and clear form and is explained by examples. The book will be useful for anyone learning the Java programming language.