At what stages does the source code transformation occur during compilation?

The process of transforming source code into Android involves several stages:

1. Compilation of Java/Kotlin into JVM bytecode — the source code is compiled into Java bytecode (.class files).

2. Conversion of bytecode into DEX (Dalvik Executable) — using the dx or d8 tool, the bytecode is combined and optimized into the DEX format, which is used by the Android virtual machine.

3. Optimization and packaging — DEX files are optimized (for example, using ProGuard or R8 to reduce size and obfuscate) and packaged into an APK along with resources.

4. Loading and execution on the device — Android Runtime (ART) loads the DEX files and executes them, possibly performing compilation into machine code (AOT) or JIT compilation during runtime.

Thus, the source code undergoes compilation into bytecode, conversion into DEX, optimization, and packaging for execution on an Android device.