May 6, 2020 ... If you're not already familiar with it, read through the Java Native Interface
Specification to get a sense for how JNI works and what features are ... (In the
C++ version, they're classes with a pointer to a function table and a member
function for each JNI function that indirects through the table.) ... The "jni.h"
include file provides different typedefs depending on whether it's included into C
or C++. ... Until a thread is attached, it has no JNIEnv, and cannot make JNI calls.