How to obtain JNI interface pointer (JNIEnv *) for asynchronous calls

by

You can obtain a pointer to the JVM (JavaVM*) with JNIEnv->GetJavaVM. You can safely store that pointer as a global variable. Later, in the new thread, you can either use AttachCurrentThread to attach the new thread to the JVM if you created it in C/C++ or simply GetEnv if you created the thread in java code which I do not assume since JNI would pass you a JNIEnv* then and you wouldn’t have this problem.

    // JNIEnv* env; (initialized somewhere else)
    JavaVM* jvm;
    env->GetJavaVM(&jvm);
    // now you can store jvm somewhere

    // in the new thread:
    JNIEnv* myNewEnv;
    JavaVMAttachArgs args;
    args.version = JNI_VERSION_1_6; // choose your JNI version
    args.name = NULL; // you might want to give the java thread a name
    args.group = NULL; // you might want to assign the java thread to a ThreadGroup
    jvm->AttachCurrentThread((void**)&myNewEnv, &args);
    // And now you can use myNewEnv

More Related Contents:

  1. Calling a java method from c++ in Android
  2. Embed Java into a C++ application?
  3. What does the registerNatives() method do?
  4. How to pass C structs back and forth to Java code in JNI?
  5. How to compile dynamic library for a JNI application on linux?
  6. How to call C++ from Java?
  7. passing string array from java to C with JNI
  8. Generating Java interface with SWIG
  9. JNI Calls different in C vs C++?
  10. Is it possible to use sun.misc.Unsafe to call C functions without JNI?
  11. How do I convert jstring to wchar_t *
  12. Attach to already running JVM
  13. SWIG (v1.3.29) generated C++ to Java Vector class not acting properly
  14. C++ ifstream.getline() significantly slower than Java’s BufferedReader.readLine()?
  15. How to use the same C++ code for Android and iOS?
  16. IllegalMonitorStateException on wait() call
  17. “implements Runnable” vs “extends Thread” in Java
  18. C++ equivalent of java’s instanceof
  19. Distinguishing between Java threads and OS threads?
  20. Javafx: Difference between javafx.concurent and Platform.runLater?
  21. How can the wait() and notify() methods be called on Objects that are not threads?
  22. Java volatile modifier and synchronized blocks
  23. How to make another thread sleep in Java
  24. What’s the C++ idiom equivalent to the Java static block?
  25. Setting priority to Java’s threads
  26. How do I properly do a background thread when using Spring Data and Hibernate?
  27. Use JNI instead of JNA to call native code?
  28. Is it possible to force an existing Java application to use no more than x cores?
  29. Handling Exceptions for ThreadPoolExecutor
  30. Java Synchronization [closed]

Leave a Comment