⚡ Spark

A minimal Android app with native Rust code via JNI.

🔧 Stack

• Kotlin + Jetpack Compose — UI & app logic
• Rust (via cargo-ndk) — native .so libraries loaded through JNI
• Gradle KTS — build system with a custom build_rust task

📦 How It Works

Rust code lives in app/src/main/jni/ and compiles into shared libraries (.so) for four Android architectures: arm64-v8a, armeabi-v7a, x86, x86_64.

The Gradle task build_rust runs automatically before every build via preBuild, placing the compiled .so files into app/src/main/jniLibs/. On the Kotlin side, the library is loaded with System.loadLibrary("spark_rust") and native functions are declared as external fun.

🚀 Setup

1. Install Rust Android targets:

   rustup target add aarch64-linux-android armv7-linux-androideabi i686-linux-android x86_64-linux-android
   

2. Make sure cargo-ndk is installed (the build task auto-installs it if missing).
3. Open the project in Android Studio and hit Run.

📁 Project Structure

app/
├── src/main/
│   ├── jni/              # Rust crate
│   │   ├── Cargo.toml
│   │   └── src/lib.rs
│   ├── jniLibs/          # compiled .so output (auto-generated)
│   ├── kotlin/           # Kotlin sources
│   └── res/              # Android resources
└── build.gradle.kts      # includes build_rust task