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Java JDK

The Java Development Kit includes the javac compiler and java launcher.

What it is for

Build and run the complete Main.java examples locally. A runtime alone may not include javac.

Install it

  1. Use the official Java learning setup guide to choose and install a supported JDK suitable for the lesson. Reopen your terminal after installing.

Official setup instructions ↗

Open it

  1. Open your practice folder in VS Code, then Terminal → New Terminal and select PowerShell.

Check it is installed — then verify

Where · PowerShell

At the PowerShell prompt. Type the command, then press Enter. Tool guide

Check both the launcher and compiler.

java --version
javac --version

What you should see: Both commands print versions. If javac is missing, check the JDK installation and PATH.

Try one small thing

Where · PowerShell

At the PowerShell prompt. Type the command, then press Enter. Tool guide

Save the lesson’s complete download as Main.java in your practice folder. In that folder’s PowerShell terminal, run each line in order.

javac Main.java
java Main

What you should see: The first command creates a class file. The second runs Main and prints the example’s result.

If something looks different

  1. Public class Main must be in Main.java, including capitalisation.
  2. Java and javac use different versions: check which installations are on PATH.

Lessons using this tool

Some use it only for optional local practice. Each lesson explains what you actually need.

Java · 41 lessons

Official help

Guide reviewed 2026-09-09. Menu labels can differ between versions.