Java-GI flatpak application template

This project can be used as a template for a GNOME application, developed with Java-GI. The project is setup to be built and installed as a flatpak application.

The application is built with Gradle. All additional resources (icons, translations, desktop file, etc) are installed with Meson. The Flatpak manifest will first run Gradle and then Meson.

Features:

• GNOME 48 & Adwaita example application, written in Java (OpenJDK 23)
• Compilation and installation of settings schema and gresource bundle
• Translated with GNU Gettext
• Template icons, desktop file, metainfo file
• Build and install as a Flatpak application

The template application is called "example" and uses the application id "org.domain.Example". This isn't dynamically configurable (yet), so you'll have to search and replace this manually. You'll also want to replace the COPYING and README.md files with your own versions.

Installation instructions

1. Clone this repository into a local folder.

2. Install the GNOME 48 Sdk and Platform runtime:

   flatpak --user install org.gnome.Platform//48 org.gnome.Sdk//48
   

3. Install the OpenJDK flatpak extension:

   flatpak --user install org.freedesktop.Sdk.Extension.openjdk//24.08
   

4. Build and install the application:

   flatpak-builder --force-clean --user --install build/flatpak data/org.domain.Example.json
   

5. Run the application:

   flatpak run org.domain.Example
   

Developing the application

You can open the project folder in IntelliJ IDEA and it will automatically load the Gradle project. To run the application from IntelliJ, start the application gradle task.

Be aware that a locally running application cannot load settings and translations, but you can load the gresource bundle, provided it is compiled first. You can automate that with a custom Gradle task:

tasks.register('compileResources', Exec) {
    commandLine 'glib-compile-resources',
                '--sourcedir=src/main/gresource',
                '--target=build/org.domain.Example.gresource',
                'data/org.domain.Example.gresource.xml'
}

tasks.named('compileJava') {
    dependsOn compileResources
}

This will create a compiled gresource bundle in the build folder, so don't forget to change the RESOURCE_DIR in Example.java to "build".

Translations

The application is translations with GNU gettext. It is initialized in the main method in Example.java.

With gettext, all translatable strings in Java source code, UI files, and other resources, are translated in the same way. The only requirement is that all files that contain translatable strings, are added to po/POTFILES.in.

To create translatable strings in Java, add a static import of org.javagi.util.Intl.i18n and use i18n("text to translate"). Comments that start with TRANSLATORS: will be included in the po-files.

More information about gettext and meson is available on the meson website.

To recompile the example.pot file, run:

meson setup ../builddir
meson compile example-pot -C ../builddir

Regenerate the po-files by running:

meson compile example-update-po -C ../builddir

The template application includes one translation (nl). Add or remove languages in po/LINGUAS.

Adding dependencies

When you change any of the dependencies in the Gradle build file, regenerate the sources file that is used by flatpak-builder in the offline build:

./gradlew flatpak-gradle-generator --no-configuration-cache

Uninstalling

Run flatpak uninstall org.domain.Example to remove the application.