Lessons

Start your programming journey with Java together with CodeGym! Learn why your experience and age are an advantage, how Java opens doors to the world of games, web, mobile, and cloud applications, and how community support will help you become a Junior Java Developer. Thousands of people have already changed their lives — now it’s your turn!

In this lecture, you will learn what commands are in programming, how a minimal program in Java 21+ works, what the main() method is, and how to write your first program that prints text to the screen. Everything is explained simply, with examples and a step-by-step guide for beginners.

In this lecture, you will get acquainted with the commands for printing to the screen in Java: System.out.println and System.out.print. You will learn how to correctly output numbers and strings, how these commands differ, how to concatenate strings, and you will also go through typical beginner mistakes.

In this lecture you will learn what variables are in Java, how they work, how to declare and use them, and you will also get familiar with variable naming rules. Everything is explained with simple analogies and code examples.

In this lecture, you will learn how to declare variables in Java, get acquainted with the basic data types ( int and String), learn to assign values, print variables to the screen, and concatenate strings with numbers.

In this lecture you will learn why a compiler is needed in Java, how it works, what errors it can find, and you will also get acquainted with comments in code: their types, purpose, and amusing examples from programmers’ lives.

In this final lecture of level one, you will learn why Java is one of the most in-demand programming languages, where it is used (from banking to mobile apps), and you will recap your first achievements on CodeGym. Congratulations on completing the first level, and we invite you to keep going!

In this lecture, you will learn how the information revolution changed the world, why IT companies became the largest and most valuable, what opportunities a career in IT opens up, and why now is the best time to become a programmer. Examples, numbers, and inspiring facts!

In this lecture you will learn how to work with integers in Java using the int type: value range, declaring variables, assignment, arithmetic operations, division, remainder, increment and decrement. Examples and explanations will help you quickly master the basics of working with integer variables.

In this lecture you’ll get acquainted with the String type in Java: you’ll learn how to create and initialize string variables, perform concatenation, escape special characters, and use basic methods for working with text. Practical examples and explanations will help you work confidently with strings in your programs.

In this lecture, you will learn how to convert values between strings and numbers in Java, why this is needed, what methods exist, and what to pay attention to when working with data types. Code examples and explanations will help you avoid common mistakes during conversion.

Dive into the basics of how memory works in Java: how variables are placed in RAM, what addressing is, how primitive types and objects are arranged, and why programmers count from zero. This lecture will help you understand how Java manages memory and what happens “under the hood” when working with variables and strings.