Manage Java runtimes fast.

Language: English | 中文 · Website: rururunu.github.io/Jir

jir installs JDKs and switches between them with a single command — Java 8, 17, 21 and vendors like Temurin, Corretto, Zulu, Oracle and Microsoft all live behind one stable path, so you never edit JAVA_HOME by hand again.

Quick Start

# install (Windows x64, no admin rights needed)
iex (New-Object Net.WebClient).DownloadString('https://github.com/rururunu/Jir/releases/download/v0.2.4/install.ps1')

jir ls -i        # see what you can install
jir i 21         # install Java 21 (asks which vendor you mean)
jir use 21       # switch to it — one command, nothing else to change
jir current      # confirm what is active

Once JAVA_HOME points at home\occupy inside your install (the GUI installer can set it for you), every later switch is a single jir use. Prefer a normal Windows installer? Grab the GUI installer instead — both channels are described under Install.

What It Does

• One stable path. Every JDK lives under home/; jir use re-points home/occupy with a directory junction — instant, and nothing gets copied.
• Vendor-aware targets. 21 asks which vendor you mean, 21:temurin pins it, and listings show the vendor and build of every JDK you have.
• Install many, switch freely, remove cleanly. Java 8, 17, 21, … from different vendors coexist side by side, and jir uni deletes the ones you are done with.
• Works offline. jir ls, jir current and jir use <spec> need no network: the version index is cached for an hour, and a stale copy is used when the network is unreachable.
• Keeps itself current. jir update upgrades jir to the newest release in place.

Commands

A target is either a feature version (21) or a full version:distro pair (21:temurin). Give a version only, and jir asks which vendor you mean.

Aliases: ls = list, i = install, u = use, uni = uninstall, cur = current, up = update. The same table is printed by jir -h, in colour.

* marks the active JDK, + marks one that is installed but not active, and a blank entry is not installed yet. The glyphs differ, so the state is readable without colour.

Install

The version index and the installer target Windows x64 only. The runtime home can be relocated with the JIR_HOME environment variable.

The recommended way is the GUI installer: it records the installation, so jir shows up in "Apps & features" and can be uninstalled normally, and it reuses the directory of an existing installation instead of creating a second copy. The PowerShell one-liner below is the other channel.

Do not mix the two. Each keeps its own install directory and its own JDK library under home/, so installing both leaves two unrelated copies of jir on PATH.

Either way, jir update upgrades whichever copy you run, so you normally do not need to download a new installer again.

GUI Installer

Download jir-<version>-windows-x64-gui-setup.exe from the releases page and run it.

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

PowerShell One-Liner

This is the portable path. It ships no uninstall.exe, so removing it means deleting its directory and its PATH and JIR_HOME entries yourself.

iex (New-Object Net.WebClient).DownloadString('https://github.com/rururunu/Jir/releases/download/v0.2.4/install.ps1')

It downloads the portable archive, verifies its SHA-256 against the release's SHA256SUMS.txt, extracts it to %LOCALAPPDATA%\jir\bin, adds that directory to your user PATH, and sets JIR_HOME. It needs no administrator rights.

Point JAVA_HOME at %LOCALAPPDATA%\jir\home\occupy and you are done — jir keeps that path pointing at whichever JDK is active.

curl.exe -fL -o jir.zip https://github.com/rururunu/Jir/releases/download/v0.2.4/jir-0.2.4-windows-x64.zip
curl.exe -fL -o SHA256SUMS.txt https://github.com/rururunu/Jir/releases/download/v0.2.4/SHA256SUMS.txt
Get-FileHash .\jir.zip -Algorithm SHA256   # compare with SHA256SUMS.txt
Expand-Archive .\jir.zip -DestinationPath "$env:LOCALAPPDATA\jir\bin"

wget -O jir.zip https://github.com/rururunu/Jir/releases/download/v0.2.4/jir-0.2.4-windows-x64.zip

Directory Layout

Everything lives under the install directory:

<install>/
├── jir.exe
├── uninstall.exe
└── home/
    ├── 21/
    │   └── temurin/
    ├── 17/
    │   └── zulu/
    ├── occupy/            points to the active JDK
    ├── .jir-current       records which JDK is active
    └── .meta/             cached vendor and build info per JDK

home/occupy points to the active JDK. The last two entries are managed for you: .jir-current is what lets jir current answer without a network call, and .meta/ is what lets the listings show a vendor name and build number. Set JIR_HOME to move the whole home/ tree somewhere else.

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.

Technical Documentation

How jir works internally — the on-disk state, the version index format and its cache, and the execution path of every command — is documented in TECHNICAL.md.