title: how to stop continuous scanning of QR code?
body: <p>**this is my code, i want is after a scan for the first-time callApi() method should call, but it keep on scanning **</p>
  
  <pre><code>  @Override
  public void handleResult(Result result) {
  
      System.out.print("BAR_CODE  "+ result.getContents());
      System.out.print("BAR_CODEE  "+result.getBarcodeFormat().getName());
      barcode_number = result.getContents();
      productcode.setText(result.getContents());
  
      //resume Camera
      scanner_bar.resumeCameraPreview(this);
  
      dialog = new ProgressDialog(getActivity());
      dialog.setCancelable(true);
      dialog.setTitle("Loading");
      dialog.show();
  
      //callApi
      if(barcode_number != "") {
  
          callApi(barcode_number);
      }
  
  };
  </code></pre>