当我尝试在onCameraFrame中使用setText()时,我遇到了这个崩溃:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
基本上我有这里描述的相同问题:Android & OpenCV - App crashes on UI change
但建议的解决方案似乎不起作用。
@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
frame=inputFrame.rgba();
int match_method = Imgproc.TM_CCOEFF;
// / result matrix
int result_cols = frame.cols() - templ.cols() + 1;
int result_rows = frame.rows() - templ.rows() + 1;
Mat result = new Mat(result_rows, result_cols, CvType.CV_32FC1);
// / Matching
Imgproc.matchTemplate(frame, frame, result, match_method);
Core.normalize(result, result, 0, 1, Core.NORM_MINMAX, -1, new Mat());
Core.MinMaxLocResult mmr = Core.minMaxLoc(result);
runOnUiThread(new Runnable() {
@Override
public void run() {
myTextElement.setText("aa");
}
});
问题解决了,包括在run()中的findViewByID,否则返回null。和setText()引发异常。