jir

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jir helps you manage Java versions without fighting JAVA_HOME.

Install a JDK, switch to it, and keep your active Java runtime behind one stable path: home/occupy.

Why

If you often switch between Java 8, 17, 21, or different vendors like Temurin, Corretto, Zulu, Oracle, and Microsoft OpenJDK, jir keeps that workflow simple.

You can set JAVA_HOME to home/occupy once. After that, jir use 21:temurin switches Java without editing environment variables again.

On Windows, switching uses a directory junction, so it is fast and does not copy the whole JDK.

Install

Download or build the Windows GUI installer:

dist/jir-0.1.0-windows-x64-gui-setup.exe

The installer lets you choose where jir lives. It can also add jir to PATH and set JAVA_HOME for you.

After installing, open a new terminal and check:

jir -h

Quick Start

See what you can install:

jir ls -i

Install Java 21. If there are multiple vendors, jir will let you choose one:

jir i 21

Already know what you want?

jir i 21:temurin

Switch to it:

jir use 21:temurin

Check what is active:

jir current

Remove something you no longer need:

jir uni 21:temurin

Commands

• jir, jir -h, jir -help, jir --help: show help.
• jir ls: show installed JDKs.
• jir ls -i: show installable JDKs.
• jir i 21: install Java 21 and choose a vendor.
• jir i 21:temurin: install a specific distro.
• jir use 21: choose an installed Java 21 distro and activate it.
• jir use 21:temurin: activate a specific installed distro.
• jir current: show the active Java runtime.
• jir uni 21:temurin: uninstall a JDK after confirmation.

Directory Layout

Everything lives under the install directory:

<install>/
├── jir.exe
├── uninstall.exe
└── home/
    ├── 21/
    │   └── temurin/
    ├── 17/
    │   └── zulu/
    └── occupy/

home/occupy points to the active JDK. The installer can set JAVA_HOME to this path for you.

If Java Still Shows the Wrong Version

Open a new terminal first. Environment variables do not update inside terminals that are already open.

Then check:

where.exe java
java -version

If Windows still finds another JDK first, the installer can request administrator permission and clean up conflicting system-level Java settings.

Build

See BUILD.md.