title: android jni reading jobjectArray field fails
body: <p>I want to read the elements of a java class in native c code. </p>
  
  <p>Java class is as below</p>
  
  <pre><code>static public class GraphViewData implements GraphViewDataInterface {
      public final double valueX;
      public final double valueY;
      public GraphViewData(double valueX, double valueY) {
          super();
          this.valueX = valueX;
          this.valueY = valueY;
      }
      @Override
      public double getX() {
          return valueX;
      }
      @Override
      public double getY() {
          return valueY;
      }
  }
  </code></pre>
  
  <p>I am passing an array of this class to native function, and trying to read the <code>valueX</code> &amp; <code>valueY</code> fields.</p>
  
  <pre><code>int Java_com_example_fftplot_PlotActivity_computeFFT(JNIEnv *env, jobject thiz,jint function,jobjectArray data) {
  
  int i;
  jsize inLength = (*env)-&gt;GetArrayLength(env,data); //size of input object array
  for(i = 0; i &lt; inLength/8 ; i++){
      jobject inData = (*env)-&gt;GetObjectArrayElement(env,data,i);
      jclass inDataClass = (*env)-&gt;GetObjectClass(env,data);
      jfieldID inXval = (*env)-&gt;GetFieldID(env,inDataClass,"valueX","D");
      jfieldID inYval = (*env)-&gt;GetFieldID(env,inDataClass,"valueY","D");
      __android_log_print(ANDROID_LOG_ERROR, "inXval =", "%l",inXval);
      __android_log_print(ANDROID_LOG_ERROR, "inYval =", "%l",inYval);
  }
  }
  </code></pre>
  
  <p>But i get error , as below</p>
  
  <pre><code>01-25 17:29:15.780: W/dalvikvm(3958): JNI WARNING: JNI method called with exception pending
  01-25 17:29:15.780: W/dalvikvm(3958):              in Lcom/example/fftplot/PlotActivity;.computeFFT:(I[Lcom/jjoe64/graphview/GraphView$GraphViewData;)I (GetFieldID)
  01-25 17:29:15.780: W/dalvikvm(3958): Pending exception is:
  01-25 17:29:15.790: I/dalvikvm(3958): java.lang.NoSuchFieldError: no field with name='valueX' signature='D' in class [Lcom/jjoe64/graphview/GraphView$GraphViewData;
  01-25 17:29:15.790: I/dalvikvm(3958):   at com.example.fftplot.PlotActivity.computeFFT(Native Method)
  </code></pre>
  
  <p>What i am doing wrong, also, what is the meaning of <code>JNI WARNING?</code>. How to solve it?</p>