SDK Extension for OpenJDK 26

This extension contains the OpenJDK 26 Java Runtime Environment (JRE) and Java Developement Kit (JDK).

OpenJDK 26 is the current latest version. This is not a long-term support (LTS) version and will be periodically updated as new JDKs are released.

For the current LTS version, see the OpenJDK 25 extension.

For the previous LTS version, see the OpenJDK 21 extension.

Usage

You can bundle the JRE with your Flatpak application by adding it to sdk-extensions in your Flatpak manifest and executing the /usr/lib/sdk/openjdk/install.sh script.

Simplified example to make the JRE available at runtime:

id: org.example.MyApp
runtime: org.freedesktop.Platform
runtime-version: '25.08'
sdk: org.freedesktop.Sdk
sdk-extensions:
  - org.freedesktop.Sdk.Extension.openjdk

modules:
  - name: openjdk
    buildsystem: simple
    build-commands:
      - /usr/lib/sdk/openjdk/install.sh
  - name: myapp
    buildsystem: simple
    ...

...

finish-args:
  - --env=PATH=/app/jre/bin:/app/bin:/usr/bin

To additionally make the JRE available at buildtime of module myapp, set build-options.append-path accordingly:

...

modules:
  ...
  - name: myapp
    buildsystem: simple
    build-options:
      append-path: /usr/lib/sdk/openjdk/jvm/openjdk-26/bin
    ...

Development

Build and install

flatpak-builder --user --install --force-clean flatpakbuildir org.freedesktop.Sdk.Extension.openjdk.yaml

Uninstall

flatpak uninstall --user org.freedesktop.Sdk.Extension.openjdk