Setting Up Java (JDK 25)

Do this once before Part 1. Two things to install: the JDK, and an IDE.

1. Install the JDK

The JDK (Java Development Kit) is what lets you compile and run Java code. This series uses JDK 25, the current long-term support (LTS) release, so it'll keep getting updates the longest before you'd need to upgrade again.

Go to jdk.java.net/25 for the free OpenJDK build, or oracle.com/java/technologies/downloads for Oracle's build. Either works for this series.
Pick the installer for your OS (Windows, macOS, or Linux).
Run it and go through the defaults. Note the install path if you're prompted for one; you won't usually need it again, but it's good to know where it lives.

To confirm it installed, open a terminal and run:

java -version

You should see something referencing 25.

2. Install an IDE

An IDE (integrated development environment) is what you'll actually write code in. This series uses IntelliJ IDEA Community Edition, which is free. If you already have a preference (VS Code with the Java extension, Eclipse), that's fine too; everything in this series is standard Java and will work anywhere.

Go to jetbrains.com/idea/download.
Download the Community Edition (free, not the paid Ultimate).
Run the installer, go through the defaults.

3. Create your project

Open IntelliJ.

New Project
Under SDK, select JDK 25. If it's not listed, click "Add SDK" and point it at the JDK install path from step 1.
Skip the project template.
Name the project intro-java. This is the folder everything in this series lives in.
Finish. You'll land on an empty project with a src folder — that's where your code goes.

That's it. You're ready for Part 1.