Native macOS launcher for Java apps, used by JavaPackager as the executable inside the .app bundles it generates (macStartup = UNIVERSAL, ARM64 or X86_64; UNIVERSAL is the default since JavaPackager 2.0.0).
It's an Objective-C program (src/nativeStub.m) that reads the Java settings from the app's Info.plist (Apple style Java/JavaX dictionary or Oracle style keys), looks for a suitable JVM (the bundled one in Contents/PlugIns, then the installed ones), runs the optional bootstrap script and launches the main class. Running as a native binary, macOS sees the app itself rather than a shell, so it runs natively on Apple Silicon and Intel without Rosetta.
On macOS, with the Xcode command line tools:
make universal
This builds build/arm64/, build/x86_64/ and build/universal/nativeJavaApplicationStub. Every push and pull request is built by the Build workflow.
Run the Compile and release workflow (Actions tab). It creates a release named after the date (e.g. 20251202.010109) with three assets: nativeJavaApplicationStub (universal), nativeJavaApplicationStub.arm64 and nativeJavaApplicationStub.x86_64.
To use a release in JavaPackager, set its version in the updateNativeJavaApplicationStub task of JavaPackager's build.gradle and run ./gradlew updateNativeJavaApplicationStub, which downloads the three binaries into src/main/resources/mac.
This repository started as a fork of tofi86/universalJavaApplicationStub, a Bash launcher that is now deprecated. The native launcher was written here as its replacement and follows the same Info.plist conventions. The Bash script used with macStartup=SCRIPT is now maintained in JavaPackager (src/main/resources/mac/universalJavaApplicationStub.sh).