Claude Cursor Skill

jni-rs-bindings

jni-rs conventions for exposing a Rust core to Java/JVM: JNI export naming, JNIEnv usage, string conversion, exception checks/throws, global references, and library loading. Load when generating or reviewing jni-rs Java/JVM bindings for a Rust library.

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goldziher/ai-rulez 162 16 forks MIT Updated 5h ago

Part of goldziher/ai-rulez — 151 skills

Install

skills CLI npx skills add https://github.com/Goldziher/ai-rulez/tree/main/internal/builtins/bindings/jni-rs/skills/jni-rs-bindings

Claude Code claude plugin marketplace add https://llmmart.ai/marketplace.json && claude plugin install goldziher-ai-rulez@llmmart

Git git clone https://github.com/Goldziher/ai-rulez.git

The skills CLI installs just this skill, for any of its supported agents. Claude Code installs the whole goldziher/ai-rulez collection as a plugin from our marketplace. Git is the plain clone.

Skill manifest

Use jni crate for Rust-Java/JVM interop. Functions must be #[no_mangle] pub extern "system".
Follow JNI naming: Java_com_example_ClassName_methodName. Match Java native method signatures exactly.
Use JNIEnv for all JNI operations. Access Java types via JObject, JString, JClass wrappers.
String conversion: env.get_string(&jstring) to read, env.new_string("value") to create.
Error handling: check env.exception_check() after JNI calls. Throw Java exceptions via env.throw_new().
Global references (env.new_global_ref()) for objects accessed across threads or native calls.
Build with cargo build --release to produce shared library. Load in Java with System.loadLibrary().
Test Java side with JUnit, Rust core logic with standard #[test]. Integration tests via JNI calls.
Keep JNI layer thin — business logic in Rust, Java provides API surface.
Memory: JNI local references are auto-freed on native return. Use env.delete_local_ref() in loops.
Anti-patterns: holding JNI references across threads without global refs, ignoring exception checks, unwrap() in JNI functions.

Files (ai-rulez)

SKILL.md 1.4 KB

---
name: jni-rs-bindings
description: "jni-rs conventions for exposing a Rust core to Java/JVM: JNI export naming, JNIEnv usage, string conversion, exception checks/throws, global references, and library loading. Load when generating or reviewing jni-rs Java/JVM bindings for a Rust library."
---

- Use `jni` crate for Rust-Java/JVM interop. Functions must be `#[no_mangle] pub extern "system"`.
- Follow JNI naming: `Java_com_example_ClassName_methodName`. Match Java native method signatures exactly.
- Use `JNIEnv` for all JNI operations. Access Java types via `JObject`, `JString`, `JClass` wrappers.
- String conversion: `env.get_string(&jstring)` to read, `env.new_string("value")` to create.
- Error handling: check `env.exception_check()` after JNI calls. Throw Java exceptions via `env.throw_new()`.
- Global references (`env.new_global_ref()`) for objects accessed across threads or native calls.
- Build with `cargo build --release` to produce shared library. Load in Java with `System.loadLibrary()`.
- Test Java side with JUnit, Rust core logic with standard `#[test]`. Integration tests via JNI calls.
- Keep JNI layer thin — business logic in Rust, Java provides API surface.
- Memory: JNI local references are auto-freed on native return. Use `env.delete_local_ref()` in loops.
- Anti-patterns: holding JNI references across threads without global refs, ignoring exception checks, `unwrap()` in JNI functions.