JNI findClass does't run properly

Question

Hello,
I'm new with jni ... i'm tryng to access a java class from inside a c native code in order to map such class to a c struct.
More in depth, for example, I have a java class with 2 fields of type int (final int id=1, final int value=2) ... once I load such class inside the native code and print the values I obtain 0 for both with no errors.
Heare is the java code:
jniStruct.java
package jniStruct;
public class jniStruct {
     private native int ccode();
     static     {
          System.loadLibrary("cJavaInterface");
     public static void main(String[] args) {
          jniStruct jnistruct = new jniStruct();
          Js s = new Js();          
          int retCode = jnistruct.ccode();
}the java class Js.java
package jniStruct;
public class Js {
     final int id=1;
     final int value=2;
}and finally the c code
#include "jni.h"
#include "jniStruct_jniStruct.h"
JNIEXPORT jint JNICALL Java_jniStruct_jniStruct_ccode (JNIEnv *env, jobject obj) {
  int l_id;
  long l_value;
  jclass cls = (*env)->FindClass(env,"jniStruct/Js");
  jfieldID idID = (*env)->GetFieldID(env, cls, "id", "I");
  jfieldID valueID = (*env)->GetFieldID(env,cls, "value", "I");
  l_id = (*env)->GetIntField(env, cls ,idID);
  l_value = (*env)->GetIntField(env, cls ,valueID);
  printf("--- %d %d\n",l_id,l_value);
}with the output:
$ --- 0 0any suggestion? thank you
Stefano

Answer 1

Sorry, I've misunderstood the meaning of words "error checking" ... I thought that possible errors in C code would have risen during compilation ... I simple didn' read the chapter about exceptions.
Now the code works!
JNIEXPORT jint JNICALL Java_jniStruct_jniStruct_ccode (JNIEnv *env, jobject obj) {
  jint l_id;
  jint l_value;
  jclass cls = (*env)->FindClass(env,"jniStruct/Js");
  jmethodID clsID = (*env)->GetMethodID(env, cls, "<init>", "()V");
  jobject obj = (*env)->NewObject(env, cls, clsID);
  jfieldID idID = (*env)->GetFieldID(env, cls, "id", "I");
  jfieldID valueID = (*env)->GetFieldID(env,cls, "value", "I");
  l_id = (*env)->GetIntField(env, obj, idID);
  l_value = (*env)->GetIntField(env, obj ,valueID);
  printf("--- %d %d\n",l_id,l_value);
}Thank you
Stefano