JNI

This page is over JNI, The Java Native Interface.

Frequent Caveats

References:

• Sheng Liang, The Java Native Interace — Programmer's Guide and Specification, Addison Wesley.

Don't cache JNIEnv between threads

Each thread gets its own value of JNIEnv

Don't truncate jboolean arguments

jboolean type is actually a 8-bit type, so value like 256/512 would actually be treated like false

Don't mix thread models (green thread vs native thread) if models are different

Cache field / Method ID at the time class is created

Better performance, and avoid using the wrong field/method if a sub-class that overrides some field/method is passed.