How to set values of members of a class (if the member is another class)?
Hi,
I'm a C++ programmer but new to Java. I have a structure (or class in Java) that has two members, one int and another GUID (which is another class). I'm trying to access that from C++ DLL and I can access the int member but when I try to access members of GUID, it fails. Can someone guide me if I'm doing it correctly?
I appreciate your help. Here is the code...
//Java code
publicclass CSMSample
{
publicstaticclass GUID
{
publicintData1;
publicshortData2;
publicshortData3;
publicbyte[]Data4;//unsigned char Data4[8]
}
publicstaticclass SYSTEMTIME
{
publicshort wYear;
publicshort wMonth;
publicshort wDayOfWeek;
publicshort wDay;
publicshort wHour;
publicshort wMinute;
publicshort wSecond;
publicshort wMilliseconds;
}
publicstaticclass Result
{
publicint ReturnVal;
public GUID ComponentGUID;
}
publicnativestaticint SMProcess(Result result);
publicstaticvoid main(String[] args)
{
Result result =new Result();
SMProcess(result);
//.....
}
static
{
try
{
// load library...
}
catch (Exception e)
{
//....
}
}
}
// C++ code
// When I do GetObjectField on Result object (that I received as parameter), to get the member which is GUID, it fails.
JNIEXPORT jint JNICALL Java_CSMSample_SMProcess (
JNIEnv* env, jclass, jobject joResult)
{
jclass jclsResult = env->GetObjectClass(joResult);// Success
// Set ReturnVal.ReturnVal (int)
jfieldID fid_RES_ReturnVal = env->GetFieldID(jclsResult,"ReturnVal","I");// Success
env->SetIntField(joResult, fid_RES_ReturnVal, 777);// Success
// Set ReturnVal.ComponentGUID (GUID)
jfieldID fid_RES_ComponentGUID = env->GetFieldID(jclsResult,"Purpose","LCSMProcess$GUID;");// Success
jobject joRES_ComponentGUID = env->GetObjectField(joResult, fid_RES_ComponentGUID);//This FAILS (joRES_ComponentGUID is zero)
jclass jclsRES_ComponentGUID = env->GetObjectClass(joRES_ComponentGUID);
jfieldID fid_RES_CGUID_Data1 = env->GetFieldID(jclsRES_ComponentGUID,"Data1","I");
jfieldID fid_RES_CGUID_Data2 = env->GetFieldID(jclsRES_ComponentGUID,"Data2","S");
jfieldID fid_RES_CGUID_Data3 = env->GetFieldID(jclsRES_ComponentGUID,"Data3","S");
jfieldID fid_RES_CGUID_Data4 = env->GetFieldID(jclsRES_ComponentGUID,"Data4","[B");
jint jtmpsize = sizeof(g_myGuid.Data4);
jbyteArray jbaCGUID_Data4 = env->NewByteArray (jtmpsize);
env->SetByteArrayRegion(jbaCGUID_Data4, 0, jtmpsize, (const jbyte*)g_myGuid.Data4);
env->SetIntField(jclsRES_ComponentGUID, fid_RES_CGUID_Data1, (jint) g_myGuid.Data1);
env->SetShortField(jclsRES_ComponentGUID, fid_RES_CGUID_Data2, (jint) g_myGuid.Data2);
env->SetShortField(jclsRES_ComponentGUID, fid_RES_CGUID_Data3, (jint) g_myGuid.Data3);
env->SetObjectField(jclsRES_ComponentGUID, fid_RES_CGUID_Data4, (jint) g_myGuid.Data4);
return S_OK;
}
