Learn Java

Write and run real Java right in your browser — compiled for real, no setup. Master the core 20% of Java that powers 80% of the code you will actually write.

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Module 1

Java Basics

Your first real, compiled Java programs.

Hello, World! Printing Two Lines Comments Printing Numbers Java as a Calculator

Module 2

Variables & Types

Store data with Java's core types.

Your First Variable (int) Decimals (double) Text (String) Doing Math with Variables True or False (boolean)

Module 3

Working with Strings

Join and transform text.

Joining Strings Mixing Text and Numbers String Length UPPERCASE Does It Contain?

Module 4

Making Decisions

if, else, and logic.

Comparisons are Booleans The if Statement if / else else if Combining with &&

Module 5

Loops & Repetition

Make Java repeat work for you.

Your First for Loop Counting from 1 The while Loop The Accumulator Pattern The % Operator Final Boss: FizzBuzz Lite