@Override
  protected void onResume() {
    super.onResume();
    final TextView sensorValues = (TextView) findViewById(R.id.sensor_values);
    sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    Sensor sensor = sensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY);
    gravityListener =
        new SensorEventListener() {
          @Override
          public void onSensorChanged(SensorEvent event) {
            double length =
                Math.sqrt(
                    event.values[0] * event.values[0]
                        + event.values[1] * event.values[1]
                        + event.values[2] * event.values[2]);
            double alfa = Math.asin(event.values[0] / length) * 180 / Math.PI;
            double beta = Math.asin(event.values[1] / length) * 180 / Math.PI;
            sensorValues.setText(alfa + "\n" + beta);
          }

          @Override
          public void onAccuracyChanged(Sensor sensor, int accuracy) {}
        };
    sensorManager.registerListener(gravityListener, sensor, SensorManager.SENSOR_DELAY_GAME);
  }
 @Override
 protected void onPause() {
   super.onPause();
   sensorManager.unregisterListener(gravityListener);
 }
 @Override
 protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
 }