Access Violation in CallStaticVoidMethod() using JNI

Question

Hey all,
I have a C++ app which I successfully used about a year ago to put up a Java dialog from within QuarkXPress, which has a C/C++ API. I got it out and rebuilt it and ran it, and I am now getting an Access Violation (0xC0000005) exception in JVM.dll somewhere. I am getting the exception in the CallStaticVoidMethod() call. Here is the relevant snippet from the method I am using: if anyone can spot anything obviously amiss, I would appreciate knowing about it! (This snippet borrows heavily from the "invoke.c" example program in the JNI tutorial.)
  JavaVM *jvm;
  jint res;
  jclass cls;
  jmethodID mid;
  jthrowable except = NULL;
  JavaVMInitArgs vm_args;
  JavaVMOption options[2];
  char newcpath[512];
  char newlibpath[512];
  sprintf (newcpath, "-Djava.class.path=.;C:\\Program Files\\QuarkXpress 4.0\\XTENSION"); 
  sprintf (newlibpath, "-Djava.library.path=.;C:\\Program Files\\QuarkXpress 4.0\\XTENSION");
  options[0].optionString = newcpath;
  options[1].optionString = newlibpath;
  vm_args.version = 0x00010002;
  vm_args.options = options;
  vm_args.nOptions = 2;
  vm_args.ignoreUnrecognized = JNI_TRUE;
  /* Create the Java VM */
  res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
  if (res == JNI_EEXIST)
    JavaVM *jvms[1];
    jsize nVMs;
    res = JNI_GetCreatedJavaVMs(jvms, 1, &nVMs);
    jvm = jvms[0];
    jvm->AttachCurrentThread((void**)&env, NULL);
  else if (res < 0)
    return UNKNOWN_ERROR;
  cls = env->FindClass(g_javaName);
  if (cls == 0)
    checkException();
    destroy(jvm);
    return MISSING_CLASS;
  mid = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");
  if (mid == 0)
    destroy(jvm);
    return MISSING_METHOD;
  env->CallStaticVoidMethod(cls, mid);

Answer 1

Hi ,
The method id that you get is for the public static void main(String args[]) of a class.
mid = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");  if (mid == 0)  
destroy(jvm);   
return MISSING_METHOD; 
env->CallStaticVoidMethod(cls, mid);
Change the above line to
jstring jStringArgs[];
env->CallStaticVoidMethod(cls, mid, jStringArgs);
You need to pass an argument i.e. an array of jstring .
It is immaterial that they possess valid value or not .
LathaDhamo