FindClass Problem

Question

I have been working on connecting to a jvm through vc++ and calling a java method. I have finally got it to connect to the jvm now I am having problems with it finding the class ... here is the practice program that I am trying to do ...most of you guys/gals have seen it before ;-)
The path to my class file is :
C:/Examples/JVMtester/classes/jvmtester/testing.class
#define USER_CLASSPATH "C:/Examples/JVMtester/classes/jvmtester/"
void CTestingJVMApp::mainTest() {
     JNIEnv *env;
     JavaVM *jvm;
     jint res;
     jclass cls;
     jmethodID mid;
     jstring jstr;
     jclass stringClass;
     jobjectArray args;
#ifdef JNI_VERSION_1_2
     JavaVMInitArgs vm_args;
     JavaVMOption options[1];
     options[0].optionString = "-Djava.class.path = c:/Examples/JVMtester/classes/jvmtester";// USER_CLASSPATH;
     vm_args.version = 0x00010002;
     vm_args.options=options;
     vm_args.nOptions = 1;
     vm_args.ignoreUnrecognized = JNI_TRUE;
     /*Create the Java VM */
     res = JNI_CreateJavaVM(&jvm, (void **)&env, &vm_args);
#else
     JDK1_1InitArgs vm_args;
     char classpath[1024];
     vm_args.version = 0x00010001;
     JNI_GetDefaultJavaVMInitArgs(&vm_args);
     /*Append User_Classpath to the default system class path */
     sprintf (classpath, "%s%c%s", vm_args.classpath, PATH_SEPARATOR, USER_CLASSPATH);
     vm_args.classpath = classpath;
     /* Create Java VM */
     res = JNI_CreateJavaVM(&jvm, &env, &vm_args);
#endif
     if (res < 0) {
          fprintf(stderr, "Can't create Java VM \n");
          AfxMessageBox("Shit yet again");
          if (env->ExceptionOccurred()) {
               env->ExceptionDescribe();
          }//end if
          exit(1);
     }//end if THIS IS WHERE IT FAULTERS
          cls = env->FindClass("testing");
     if (cls == NULL) {
          AfxMessageBox("could NOT find Class");
          if (env->ExceptionOccurred()) {
               env->ExceptionDescribe();
          }//end if
          exit(1);
          //destory();
     }//end if
     mid = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");
     if (mid == NULL) {
          AfxMessageBox("could NOT find method");
          if (env->ExceptionOccurred()) {
               env->ExceptionDescribe();
          }//end if
          exit(1);
          //destroy();
     }//end if
     jstr = env->NewStringUTF(" from C!");
     if (jstr == NULL) {
          AfxMessageBox("could NOT create jstring.");
          if (env->ExceptionOccurred()) {
               env->ExceptionDescribe();
          }//end if
          exit(1);
     }//end if
     stringClass = env->FindClass("java/lang/String");
     args = env->NewObjectArray(1, stringClass, jstr);
     if (args == NULL) {
          AfxMessageBox("could NOT create Object Array");
          if (env->ExceptionOccurred()) {
               env->ExceptionDescribe();
          }//end if
          exit(1);
     }//end if
     //env->CallStaticVoidMethodA(cls, mid, args);
     env->CallStaticVoidMethodV(cls, mid, (char *)args);
     jvm->DestroyJavaVM();

Answer 1

> I can take out the spaces but can't use a back slash in C++ that is an escape character, I could put two '//' that would work.
Assuming you mean '\\' there instead of '//', that is exactly what I meant.
> I got the C++ program to run and get through all the init (i.e. create JVM, find Class, find Method) but now it is not executing the java method, so I am guessing it is not finding it still.
If the FindClass call succeeds then it means your classpath is now correct. But the next problem is:
    jobjectArray args = env->NewObjectArray (1, stringClass, jstr);
    env->CallStaticVoidMethodV (cls, mid, (char *) args);First, casting a jobjectArray to a (char *) is bogus. They are totally different things. The cast does compile but produces a (char *) value that doesn't make sense.
Next, CallStaticVoidMethodV takes a va_list as its last argument, and the args variable here is definitely not a va_list no matter how you cast it. (The "V" call functions are basically for usage by a wrapper function that itself takes a variable number of arguments.) You need to use either CallStaticVoidMethod or CallStaticVoidMethodA. It's important to first understand exactly how argument passing works for each kind of Call function (varargs vs. va_list vs. jvalue array) in order to choose the right one.
-slj-