This repository contains a tiny demo Android application showcasing how to integrate a Rust library into an Android project using JNI (Java Native Interface). The Rust library provides a simple string reverser function, demonstrating how to call native Rust code from Android Kotlin/Java.
- Minimal setup to connect Rust and Android
- Example Rust function that reverses a string
- Kotlin code calling Rust via JNI
- Working build scripts for both Rust and Android
- The main goal of this project is to serve as a starting point or reference for developers interested in adding Rust code to their Android applications.
use jni::JNIEnv;
use jni::objects::{JClass, JString};
use jni::sys::jstring;
/// Reverses a string by reversing the order of its characters.
///
/// # Examples
///
/// ```
/// use string_reverser::reverse_string;
///
/// assert_eq!(reverse_string("hello"), "olleh");
/// assert_eq!(reverse_string("Rust"), "tsuR");
/// ```
#[inline]
pub fn reverse_string(s: &str) -> String {
s.chars().rev().collect()
}
#[no_mangle]
pub extern "system" fn Java_com_pro2on_demorust_RustBridge_reverseString(
mut env: JNIEnv,
_class: JClass,
input: JString,
) -> jstring {
// Convert the Java string to a Rust string
let input: String = env
.get_string(&input)
.expect("Could not get Java string!")
.into();
// Reverse the string
let output = reverse_string(&input);
// Convert the Rust string back to Java string
env.new_string(output)
.expect("Could not create Java string!")
.into_raw()
}package com.pro2on.demorust
object RustBridge {
init {
System.loadLibrary("string_reverser")
}
@Suppress("MissingNativeMethod")
external fun reverseString(input: String): String
}