Question

I want to call a java method inside a pthread.

the C++ method start like this :

char* FileLoader::getStringFromFile(char* a_filename)
{
   JNIEnv *env;
   g_jvm->AttachCurrentThread (&env, NULL);
   jclass cls = env->FindClass(JAVA_FILE_LOADER_CLASS);
   ...

g_jvm points to the JavaVM object. it is set when the app start in the JNI_OnLoad() method.

When “FindClass” is called, it throws a “noClassDefFoundError” but if I call this method in the main thread, it works as expected.

Have I forgotten something ?

Answer 1

Ok, I solve the problem with the advice of technomage :

In my JNI_OnLoad() method :

jint JNI_OnLoad(JavaVM* vm, void * reserved)
{
    JNITools::g_jvm = vm;

    JNIEnv *env;
    g_jvm->AttachCurrentThread (&env, NULL);jclass tmpClass = env->FindClass("com/Framework/IO/CFileLoader");
    g_fileLoaderClass = (jclass)env->NewGlobalRef(tmpClass);
    ... 

My first test has failed because I forgot to call NewGlobalRef().

This doc helped me to understand why it is needed.