Tangentially related, I've written a barebones assembler for Android .apk files once (strictly speaking, the assembler is for .dex files, but it also comes with a set of tools to package and sign .apk files). It showed up to be surprisingly easy. I expected to stumble upon some blocker issue any time that would make it impossible for me to continue — but one just never materialized! It's written mainly in Nim and provides enough primitives to allow creating Java "stubs" for native .so libraries, so that .apk-s can be built in Nim WITHOUT JDK AT ALL. The Android NDK is still kinda needed/useful, though IIRC mainly for access to adb, and especially adb logcat (which you'll need A LOT for debugging if you try to use this contraption).
I'd love to One Day™ Rewrite It In Rust, so that we could write .apk-s purely using the Rust toolchain, just using a JNI library as appropriate, sprinkling the code with some proc-macro annotations where needed by the assembler (for stubs), and possibly adding some lines in a build.rs (for .apk packaging).
I'd love to One Day™ Rewrite It In Rust, so that we could write .apk-s purely using the Rust toolchain, just using a JNI library as appropriate, sprinkling the code with some proc-macro annotations where needed by the assembler (for stubs), and possibly adding some lines in a build.rs (for .apk packaging).
The .dex assembler itself is at: https://github.com/akavel/dali — you may like to check out the tests at: https://github.com/akavel/dali/tree/master/tests to see how using it looks like.
An example project with a simple .apk written purely in Nim (NO JDK) is at: https://github.com/akavel/hellomello/tree/flappy (unfortunately, given Nim's poor packaging story, it's most probably already bitrotten to the extent that it can't be quickly and easily built & used out of the box). I recorded a presentation about this for an online Nim conference — see: https://www.youtube.com/watch?v=wr9X5NCwPlI&list=PLxLdEZg8DR...