Question

我想在本机c代码中读取java类的元素。

Java类如下

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;
    }
}

我将此类的数组传递给本机函数，并尝试阅读valueX＆amp; valueY字段。

int Java_com_example_fftplot_PlotActivity_computeFFT(JNIEnv *env, jobject thiz,jint function,jobjectArray data) {

int i;
jsize inLength = (*env)->GetArrayLength(env,data); //size of input object array
for(i = 0; i < inLength/8 ; i++){
    jobject inData = (*env)->GetObjectArrayElement(env,data,i);
    jclass inDataClass = (*env)->GetObjectClass(env,data);
    jfieldID inXval = (*env)->GetFieldID(env,inDataClass,"valueX","D");
    jfieldID inYval = (*env)->GetFieldID(env,inDataClass,"valueY","D");
    __android_log_print(ANDROID_LOG_ERROR, "inXval =", "%l",inXval);
    __android_log_print(ANDROID_LOG_ERROR, "inYval =", "%l",inYval);
}
}

但我得到错误，如下所示

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)

我做错了，JNI WARNING?是什么意思。怎么解决？

Answer 1

no field with name='valueX' signature='D' in class [Lcom/jjoe64/graphview/GraphView$GraphViewData;

注意班级名称中的'['。您正在寻找数组类valueX中名为GraphViewData[]的字段，而不是类GraphViewData。

也许您打算将inData而不是data传递给GetObjectClass？

android jni阅读jobjectArray字段失败

1 个答案: