ClassDefNotFound error when calling Java from C++

Question

Hi all,
I have a problem with calling my java from C++ through JNI.
I have set my CLASSPATH environment varible that include path to every libary that I need. My source is as follows:
#include <jni.h>
#include <stdio.h>
int main()     
     JNIEnv               *env;
     JavaVM               *jvm;
     JavaVMInitArgs     vm_args;
     jint               res;
     jclass               cls;
     jmethodID          mid;
IMPORTANT: specify vm_args version # if you use JDK 1.1.2 and beyond
     vm_args.version = JNI_VERSION_1_4;
     vm_args.ignoreUnrecognized = JNI_TRUE;
     JNI_GetDefaultJavaVMInitArgs(&vm_args);
     /* Create the Java VM */
     res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
     if (res < 0) {
          printf("Can't create JVM\n");
          return 1;
     cls = (env)->FindClass ("dds/test/comm/listeners/NACKListenerFrame");
     if (cls == 0)     {
          printf("Can't find NACKListenerFrame Class\n");
          return 1;
mid = (env)->GetStaticMethodID(cls, "start", "()V");
     if (mid == 0)     {
          printf("Can't find NackListnerFrame.start \n");
          return 1;
     (env)->CallStaticVoidMethod((_jclass*)cls, (_jmethodID*)mid, NULL);
     jthrowable e = (env)->ExceptionOccurred();
     if (e)     {
          env->ExceptionDescribe();
          env->ExceptionClear();
     if ((jvm)->DestroyJavaVM() < 0)     {
          printf("Cannot destroy JVM./n");     
     return 0;
I deliberately left out the codebelow because I want the JVM I created to load Classes from the system's CLASSPATH variable as I have set path to every classes that I need, in that CLASSPATH variable.
JavaVMOption     options[1];
options[0].optionString=
"-Djava.class.path=.;E:/DDSproject/DDSImplementation/classes";
vm_args.options = options;
vm_args.nOptions = 1;
But it seems like unless I specify CLASSPATH in my C++ source code the JVM could not find any classes.
I tried to put the "jvm.dll" path to the first one in the System's PATH variable. It does not work either...
Gurus Pls help!!!.. I don't know what to do... I don't wanna code my CLASSPATH in my c++ source code as above.
Thanks in advance,
chancellor

Answer 1

I was thinking JVM should the classpath when it is invoked. But obviously it is not and we need to assign the classpath ourselves when invoking from native side. Thanks for pointing that out. For other people's benefit the following is the code piece I for initializing JVM.
char* str1;
          char* str2;
          char* classpath;
          str1 = "-Djava.class.path=";
          str2 = std::getenv("CLASSPATH");
          classpath = (char*)malloc(strlen(str1) + strlen(str2) + 1);
          strcpy(classpath, str1);
          strcat(classpath, str2);
          if (str2 == NULL)     {
               printf("CLASSPATH environment variable is not defined.");
               exit(1);
          m_VmArgs.version = JNI_VERSION_1_4;
          m_options[0].optionString= classpath;
          m_VmArgs.options = m_options;
          m_VmArgs.nOptions = 1;
          m_VmArgs.ignoreUnrecognized = JNI_TRUE;
          JNI_GetDefaultJavaVMInitArgs(&m_VmArgs);
          /* Create the Java VM */
          m_Res = JNI_CreateJavaVM(&m_Jvm, (void**)&m_Env, &m_VmArgs);
          if (m_Res < 0) {
               printf("Can't create JVM\n");
               exit(1);
thanks,
chancellor