Compiling Android Apps

A brief introduction to the compilation pipeline for Android apps.

Transcript

1. Compiling Android Apps
2. ART History • Android apps don’t run on the Java Virtual Machine (JVM) • The first Android vm was called Dalvik. It had some problems. • Nowadays, they run on a virtual machine called the Android Runtime (ART) ◦ Remember when Oracle sued Google of Patent/Copyright infringement? • ART makes certain affordances and optimizations for Android platform features and is actually quite different from the desktop JVM. • For example: ◦ JVM is a stack based architecture. ART is register based. ◦ ART can elect to ahead-of-time compile an app at device install time.
3. Optimized Builds The old way Kotlin source Java bytecode Optimized Java bytecode Optimized Dex bytecode kotlinc ProGuard (or DexGuard for $$$) DX (or recently D8)
4. Aside: Naming things is hard.
5. Optimized Builds The new way Kotlin source Java bytecode Optimized Dex bytecode kotlinc R8
6. Why does this matter? • Whole program optimization with nice Kotlin support • Resource shrinking • Tree shaking / 64k reference limit • Bytecode obfuscation
7. Non-Optimized Build: Left // Optimized Build: Right
8. Goodbye classes2.dex 💥
9. 35% reduction of .apk size