How to snapshot webcam streaming and save to path in javafx button event

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@FXML
    private void capImage(ActionEvent event) {
      VideoCapture cap = new VideoCapture(0);
     while(cap.isOpened()) {
     Mat frame = new Mat();
     if (cap.read(frame)) {
         Imgcodecs.write( "testcap".png", frame); // imgcodecs cannot find symbol
     }

in opencv 341 anything wrong and i am beginner programmer thank you for commennt. thank sir.