kjar

Kool Java Archive Runner (pronounced K-jarrrrgh, like a dragon pirate >:D).

Run JAR files directly via a bundled OpenJDK Flatpak with a Kirigami GUI. And optionaly generate wrapper scripts for developers who get tired of typing out flatpak run commands.

Build

flatpak remote-add --user flathub https://flathub.org/repo/flathub.flatpakrepo

flatpak-builder --install --user --install-deps-from=flathub --force-clean build-dir .flatpak-manifest.json

Use

GUI

Launch the app to open JAR files interactively:

flatpak run org.kde.kjar

KJar is also registered as a handler for .jar files so you can open them directly from your file manager.

Run a JAR file directly

flatpak run org.kde.kjar /path/to/app.jar

If Java reports an error (e.g. missing main manifest attribute) the GUI opens automatically and displays it.

JavaFX

JavaFX is bundled. JavaFX apps will work out of the box with no extra setup.

External modules

If a JAR requires external modules (e.g. a custom library distributed as a modular JAR), drop them into:

~/.local/share/kjar/modules/

They will be picked up automatically on the next run. You can open this folder directly via Advanced → Open Modules Folder.

Generate wrappers (for Developers)

Creates wrapper scripts in ~/.local/bin for all JDK tools (java, javac, jar, etc.) so they can be used like a system JDK:

flatpak run org.kde.kjar --generate-wrappers

Or via the GUI: Advanced → Generate Wrappers. Existing non-kjar binaries are never overwritten. ~/.local/bin must be in PATH.

List available tools

Via the GUI: Advanced → Show Available Tools.

Run a JDK tool directly

flatpak run org.kde.kjar java -version
flatpak run org.kde.kjar javac MyClass.java

Module-aware tools (java, javac, javadoc, jdeps, jshell, jlink, jnativescan, jpackage) automatically get the bundled JavaFX and ~/.local/share/kjar/modules/ on their module path.

License

GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL