jnienv

I'm writing a C++ app with native threads (pthreads) and I need to call some Java methods etc. I'm not sure which JNI objects can be safely cached ie stored in my C++ object for use later, possibly/probably by a different thread. I do know that if my class' methods can be called by different threads I mustn't cache the JNIEnv, but instead cache the JavaVM and get a JNIEnv by attaching the current thread. But does that also mean I can't cache anything obtained from a JNIEnv? I need to use the objects obtained by the following JNIEnv methods: FindClass, GetMethodID, NewObject, NewGlobalRef Do

I'm trying to call a Java method from C++ using JNI. To do that I've installed jdk1.7.0_51 , linking against jdk1.7.0_51\lib\jvm.lib , including jdk1.7.0_51\include and jdk1.7.0_51\include\win32 . using the following code in Visual Studio 2012 I tried to create a Java vm object - but the function always terminates my application with exit code 1 (the function doesn't return 1: my program terminates completly and sends the exit code 1). #include <iostream> #include "jni.h" int main(int argc, char*argv[]){ JNIEnv* env = nullptr; JavaVM* jvm = nullptr; JavaVMInitArgs vm_args; JavaVMOption options

JNI reference says that "Local references are valid for the duration of a native method call. They are freed automatically after the native method returns. Source: http://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/functions.html#global_local I'm kind of lost here. According to above, I must explicitly call NewGlobalRef and pass object returned from a call to NewObject . I tried this and it seems that when a GC kicks in, it does not collect my references (like something still holds onto them). Consider the following project: Main.java : package lv.example; import java.io

I am storing off JNIEnv in a global so I can call static java methods later. But is it nessasary to store off a global pointer to the JNIEnv , they way one would with any other java object, or is it a special case that does not require this. JNIEnv* globalEnvPointer; [JNICALL etc] void init(JNIENv* env, [etc]) { //required? globalEnvPointer = (JNIENv*) (env*)->GetGlobalRef(env, env); //or is this OK? globalEnvPointer = env; } Edit I'm bing a bit dumb here, all the methods that will use globalEnvPointer , are invoked within my init because my init is actually my c program's main method, which