Permissions for Android Camera QR Scanner

Question

I am creating an android application and want to integrate ZXing QR Scanner. When i launch the QRScanner activity from an Intent I get the toast saying "Permission Denied, You cannot access and camera" and the app freezes instead of asking for permission for camera.

Any help to how to correctly implement permission requests or identification of any errors I looked over would be appreciated.

      public class Qrscanner extends AppCompatActivity implements 
      ZXingScannerView.ResultHandler {

    private static final int REQUEST_CAMERA = 1;
    private ZXingScannerView scannerView;
    private static int camId = Camera.CameraInfo.CAMERA_FACING_BACK;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        scannerView = new ZXingScannerView(this);
        setContentView(scannerView);
        int currentApiVersion = Build.VERSION.SDK_INT;

        if(currentApiVersion >=  Build.VERSION_CODES.M)
        {
            if(checkPermission())
            {
                Toast.makeText(getApplicationContext(), "Permission already granted!", Toast.LENGTH_LONG).show();
            }
            else
            {
                requestPermission();
            }
        }
    }

    private boolean checkPermission()
    {
        return (ContextCompat.checkSelfPermission(getApplicationContext(), CAMERA) == PackageManager.PERMISSION_GRANTED);
    }

    private void requestPermission()
    {
        ActivityCompat.requestPermissions(this, new String[]{CAMERA}, REQUEST_CAMERA);
    }

    @Override
    public void onResume() {
        super.onResume();

        int currentapiVersion = android.os.Build.VERSION.SDK_INT;
        if (currentapiVersion >= android.os.Build.VERSION_CODES.M) {
            if (checkPermission()) {
                if(scannerView == null) {
                    scannerView = new ZXingScannerView(this);
                    setContentView(scannerView);
                }
                scannerView.setResultHandler(this);
                scannerView.startCamera();
            } else {
                requestPermission();
            }
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        scannerView.stopCamera();
    }

    public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
        final int req = requestCode;
        switch (requestCode) {

            case REQUEST_CAMERA:
                if (grantResults.length > 0) {

                    boolean cameraAccepted = grantResults[0] == PackageManager.PERMISSION_GRANTED;
                    if (cameraAccepted){
                        Toast.makeText(getApplicationContext(), "Permission Granted, Now you can access camera", Toast.LENGTH_LONG).show();
                    }else {
                        Toast.makeText(getApplicationContext(), "Permission Denied, You cannot access and camera", Toast.LENGTH_LONG).show();
                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                            if (shouldShowRequestPermissionRationale(CAMERA)) {
                                showMessageOKCancel("You need to allow access to both the permissions",
                                        new DialogInterface.OnClickListener() {
                                            @Override
                                            public void onClick(DialogInterface dialog, int which) {
                                                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
  //                                                    
   requestPermissions(new String[]{CAMERA},
   //                                                            
   REQUEST_CAMERA);

    ActivityCompat.requestPermissions(getParent(), new String[] 
    {Manifest.permission.CAMERA}, req);

                                                }
                                            }
                                        });
                                return;
                            }
                        }
                    }
                }
                break;
        }
    }

    private void showMessageOKCancel(String message, DialogInterface.OnClickListener okListener) {
        new android.support.v7.app.AlertDialog.Builder(Qrscanner.this)
                .setMessage(message)
                .setPositiveButton("OK", okListener)
                .setNegativeButton("Cancel", null)
                .create()
                .show();
    }

    @Override
    public void handleResult(final Result result) {
        final String myResult = result.getText();
        Log.d("QRCodeScanner", result.getText());
        Log.d("QRCodeScanner", result.getBarcodeFormat().toString());

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Scan Result");
        builder.setPositiveButton("Try Again", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                scannerView.resumeCameraPreview(Qrscanner.this);
            }
        });
        builder.setNeutralButton("Confirm", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
               Intent intent = new Intent(getApplicationContext(),AddKeys.class);
               intent.putExtra("publicKey",result.getText());
               startActivity(intent);
            }
        });
        builder.setMessage(result.getText());
        AlertDialog alert1 = builder.create();
        alert1.show();
    }
}

Answer 1

I had the same problem after building your cameSource. Add this line to your code, it works for me

final String[] permissions = new String[] Manifest.permission.CAMERA};

if (!ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, Manifest.permission.CAMERA)) {
    ActivityCompat.requestPermissions(MainActivity.this, permissions, RC_HANDLE_CAMERA_PERM);
}

Answer 2

There is a really simple solution to your problem. Inside the onCreate provide runtime permissions. I suggest you use the dexter library as it's the simplest way of implementing runtime permissions. Here is the link to the library: https://github.com/Karumi/Dexter