Simple compass using sensor.

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#fff" >
 
    <TextView
        android:id="@+id/tvHeading"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="40dp"
        android:layout_marginTop="20dp"
        android:text="Heading: 0.0" />
 
    <ImageView
        android:id="@+id/imageViewCompass"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tvHeading"
        android:layout_centerHorizontal="true"
        android:src="@drawable/img_compass" />
 
</RelativeLayout>

MainActivity.java

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.TextView;
 
public class MainActivity extends Activity implements SensorEventListener {
 
    // define the display assembly compass picture
    private ImageView image;
 
    // record the compass picture angle turned
    private float currentDegree = 0f;
 
    // device sensor manager
    private SensorManager mSensorManager;
 
    TextView tvHeading;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // our compass image 
        image = (ImageView) findViewById(R.id.imageViewCompass);
 
        // TextView that will tell the user what degree is he heading
        tvHeading = (TextView) findViewById(R.id.tvHeading);
 
        // initialize your android device sensor capabilities
        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    }
 
    @Override
    protected void onResume() {
        super.onResume();
         
        // for the system's orientation sensor registered listeners
        mSensorManager.registerListener(this, mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),
                SensorManager.SENSOR_DELAY_GAME);
    }
 
    @Override
    protected void onPause() {
        super.onPause();
         
        // to stop the listener and save battery
        mSensorManager.unregisterListener(this);
    }
 
    @Override
    public void onSensorChanged(SensorEvent event) {
 
        // get the angle around the z-axis rotated
        float degree = Math.round(event.values[0]);
 
        tvHeading.setText("Heading: " + Float.toString(degree) + " degrees");
 
        // create a rotation animation (reverse turn degree degrees)
        RotateAnimation ra = new RotateAnimation(
                currentDegree, 
                -degree,
                Animation.RELATIVE_TO_SELF, 0.5f, 
                Animation.RELATIVE_TO_SELF,
                0.5f);
 
        // how long the animation will take place
        ra.setDuration(210);
 
        // set the animation after the end of the reservation status
        ra.setFillAfter(true);
 
        // Start the animation
        image.startAnimation(ra);
        currentDegree = -degree;
 
    }
 
    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // not in use
    }
}