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Install the JDK

To write Java you install the JDK (Java Development Kit) — the compiler (javac), the runtime (JVM), and developer tools.

Get an LTS build

Download an LTS release (Java 21 or 25) from Eclipse Temurin (adoptium.net) — free and widely used.
Oracle, Amazon Corretto, and Azul Zulu are other solid distributions.
Install it, then verify from a terminal.

java -version     # runtime
javac -version    # compiler

You should see the version you installed. If not, the PATH isn't set (see below).

PATH & JAVA_HOME

Tools like Maven expect JAVA_HOME to point at your JDK, and java/javac to be on your PATH.

bash

# macOS/Linux (add to ~/.zshrc or ~/.bashrc)
export JAVA_HOME=/path/to/jdk
export PATH="$JAVA_HOME/bin:$PATH"

Tip: On Windows, if java -version isn't recognised, add the JDK's bin folder to the PATH environment variable and reopen the terminal.

Managing multiple versions

If you juggle projects on different Java versions, a version manager like SDKMAN! (macOS/Linux) makes switching trivial.

sdk install java 21-tem
sdk use java 21-tem

An IDE

Most developers use IntelliJ IDEA (Community edition is free) or VS Code with the Java extensions — you get autocomplete, refactoring, and one-click run/debug.

Note: You can start with just a text editor and the terminal, but an IDE dramatically speeds up real Java work.

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