Приложение для считывания QR Code

MainActivity.java

package uz.akfa.qrscanner;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.Camera;
import android.os.Bundle;
import android.os.Vibrator;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.TextView;

import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {
    SurfaceView surfaceView;
    CameraSource cameraSource;
    TextView textView;
    BarcodeDetector barcodeDetector;
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        surfaceView = (SurfaceView) findViewById(R.id.camerapreview);
        textView = (TextView) findViewById(R.id.textView);

        barcodeDetector = new BarcodeDetector.Builder(this)
                .setBarcodeFormats(Barcode.QR_CODE).build();

        cameraSource = new CameraSource.Builder(this, barcodeDetector)
                .setRequestedPreviewSize(640, 480).build();

        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                if(ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CAMERA)
                        != PackageManager.PERMISSION_GRANTED) {
                    return;
                }
                    try {
                    cameraSource.start(holder);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                cameraSource.stop();
            }
        });

        barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
            @Override
            public void release() {

            }

            @Override
            public void receiveDetections(Detector.Detections<Barcode> detections) {
                final SparseArray<Barcode> qrCodes = detections.getDetectedItems();

                if(qrCodes.size()!=0)
                {
                    textView.post(new Runnable() {
                        @Override
                        public void run() {
                            Vibrator vibrator = (Vibrator) getApplicationContext().getSystemService(Context.VIBRATOR_SERVICE);
                            vibrator.vibrate(1000);
                            textView.setText(qrCodes.valueAt(0).displayValue);
                        }
                    });
                }
            }
        });

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}