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Java Core

From your first program to classes, interfaces, collections, exceptions, lambdas, streams and a final project.

Free17 modules150 lessons3 exercises≈ 8 h

Tests check every exercise: in your browser and in the cloud

The course runs on the site: theory, quizzes and code exercises that the site checks itself, so you need nothing installed to take it. To run the lesson examples on your own computer, set it up in two steps.

  1. Install the JDK

    The lessons use Java 25 (the current long-term support release).

    • Open Eclipse Temurin 25, pick your operating system and download the JDK installer (.msi on Windows, .pkg on macOS).
    • Run the installer and accept the defaults. The installation guide shows how to check that Java is installed on Windows, macOS and Linux.

  2. Install IntelliJ IDEA

    Download IntelliJ IDEA — the free version is enough.

    • Create a new Java project and choose the JDK 25 you installed.
    • Add a class Main, paste a program from a lesson and press the green Run button beside main. JetBrains' first Java application guide walks through it with screenshots.

Syllabus