Accessing java fields from c++

Question

I have created a JNI app that needs to access the fields of the java object but when I try to access them I get an error message saying "no such field."
When I created my header file with javah I got (JNIEnv *, jclass and jobject) as my parameter list not JNIEnv * and jobject like all the documentation does.
then i try to access the fields with :
fidZone = env->GetFieldID(cls, "zone","I");
which generates the error mentioned.
Any suggestions will be greatly appreciated.
Cheers.

Answer 1

1. Here is the native code:
#include <jni.h>
#include <stdio.h>
#include "worldfl.h"
//header for external DLL I want to access
#include "GDAit.h"
JNIEXPORT jlong JNICALL
Java_worldfl_TransProjectPt(JNIEnv *env, jclass cls, jobject obj)
jfieldID fidx, fidy, fidStr, fidZone, fidTrDir;
long zone, agd2gda, iResult = 0;
double transX, transY, newX, newY, accX, accY;
/* GET the X & Y values of the coords in the world file */
cls = env->GetObjectClass(obj);
printf("%ld\n", cls);
if (cls != NULL)
fidZone = env->GetFieldID(cls, "zone","I");
fidTrDir = env->GetFieldID(cls, "agd2gda","I");
fidx = env->GetFieldID(cls, "transX","D");
fidy = env->GetFieldID(cls, "transY","D");
/*fidStr = env->GetFieldID(cls, "filename","Ljava.lang.String");*/
transX = env->GetDoubleField(obj, fidx);
transY = env->GetDoubleField(obj, fidy);
zone = env->GetDoubleField(obj, fidZone);
agd2gda = env->GetDoubleField(obj, fidTrDir);
iResult = 0;//TransProjPt("f:\\coordcalcs\\A66 National (13.09.01).gsb", agd2gda, transX, transY, zone, &newX, &newY, &accX, &accY);
else
printf("Class is NULL\n");
//env->GetDoubleField(obj, fidx) = newX;
//env->GetDoubleField(obj, fidy) = newY;
return(iResult);
2. Yes it is defined as static
private native static long TransProjectPt(worldRead wr);