Get device angle by using getOrientation() function

You now use two sensors (ACCELEROMETER and MAGNETIC_FIELD) to get that information. See blog post for more detail.

public class CompassActivity extends Activity implements SensorEventListener {  private SensorManager mSensorManager;  Sensor accelerometer;  Sensor magnetometer;  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(mCustomDrawableView);    // Register the sensor listeners    mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);    accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);    magnetometer = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);  }  protected void onResume() {    super.onResume();    mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_UI);    mSensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_UI);  }  protected void onPause() {    super.onPause();    mSensorManager.unregisterListener(this);  }  public void onAccuracyChanged(Sensor sensor, int accuracy) {  }  float[] mGravity;  float[] mGeomagnetic;  public void onSensorChanged(SensorEvent event) {    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)      mGravity = event.values;    if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)      mGeomagnetic = event.values;    if (mGravity != null && mGeomagnetic != null) {      float R[] = new float[9];      float I[] = new float[9];      boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mGeomagnetic);      if (success) {        float orientation[] = new float[3];        SensorManager.getOrientation(R, orientation);        azimut = orientation[0]; // orientation contains: azimut, pitch and roll      }    }  }}

Permissions:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

Regarding your second question. When you are registering your sensor listeners, change your code to read:

protected void onResume() {              super.onResume();              mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);              mSensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_NORMAL);          }

Google has a great demo app for orientation in their google-developer-training series called TiltSpot. Because it has an Apache license, I've taken the liberty of turning it into a small library called johnnylambada-orientation that makes getting orientation as simple adding this to your activity:

        getLifecycle().addObserver(new OrientationReporter(this, (a, p, r) -> {            Log.i("orientation","a="+a+" p="+p+" r="+r);        }));