Create our Android Compass

Android compass is implemented here. In the implementation, the final result (base on Accelerometer and Magnetic Field sensors) is show in RED, point to the north.
Create a custom View, Compass, extends View. The method update() is called from onSensorChanged() of main activity, with the updated direction.

package com.AndroidDetOrientation;
 
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
 
public class Compass extends View {
 
 private float direction;
  
 public Compass(Context context) {
  super(context);
  // TODO Auto-generated constructor stub
 }
 
 public Compass(Context context, AttributeSet attrs) {
  super(context, attrs);
  // TODO Auto-generated constructor stub
 }
 
 public Compass(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  // TODO Auto-generated constructor stub
 }
 
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  setMeasuredDimension(
    MeasureSpec.getSize(widthMeasureSpec),
    MeasureSpec.getSize(heightMeasureSpec));
 }
 
 @Override
 protected void onDraw(Canvas canvas) {
   
  int w = getMeasuredWidth();
  int h = getMeasuredHeight();
  int r;
  if(w > h){
   r = h/2;
  }else{
   r = w/2;
  }
   
  Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
  paint.setStyle(Paint.Style.STROKE);
  paint.setStrokeWidth(5);
  paint.setColor(Color.WHITE);
   
  canvas.drawCircle(w/2, h/2, r, paint);
   
  paint.setColor(Color.RED);
  canvas.drawLine(
    w/2,
    h/2,
    (float)(w/2 + r * Math.sin(-direction)),
    (float)(h/2 - r * Math.cos(-direction)),
    paint);
 
 }
  
 public void update(float dir){
  direction = dir;
  invalidate();
 }
  
}

Modify main activity, AndroidDetOrientationActivity, to update Compass.

package com.AndroidDetOrientation;
 
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.widget.TextView;
 
public class AndroidDetOrientationActivity extends Activity
 implements SensorEventListener{
  
 SensorManager sensorManager;
 private Sensor sensorAccelerometer;
 private Sensor sensorMagneticField;
  
 private float[] valuesAccelerometer;
 private float[] valuesMagneticField;
  
 private float[] matrixR;
 private float[] matrixI;
 private float[] matrixValues;
  
 TextView readingAzimuth, readingPitch, readingRoll;
 Compass myCompass;
  
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      readingAzimuth = (TextView)findViewById(R.id.azimuth);
      readingPitch = (TextView)findViewById(R.id.pitch);
      readingRoll = (TextView)findViewById(R.id.roll);
     
      myCompass = (Compass)findViewById(R.id.mycompass);
     
      sensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
      sensorAccelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
   sensorMagneticField = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
     
   valuesAccelerometer = new float[3];
   valuesMagneticField = new float[3];
 
   matrixR = new float[9];
   matrixI = new float[9];
   matrixValues = new float[3];
  }
 
 @Override
 protected void onResume() {
 
  sensorManager.registerListener(this,
    sensorAccelerometer,
    SensorManager.SENSOR_DELAY_NORMAL);
  sensorManager.registerListener(this,
    sensorMagneticField,
    SensorManager.SENSOR_DELAY_NORMAL);
  super.onResume();
 }
 
 @Override
 protected void onPause() {
 
  sensorManager.unregisterListener(this,
    sensorAccelerometer);
  sensorManager.unregisterListener(this,
    sensorMagneticField);
  super.onPause();
 }
 
 @Override
 public void onAccuracyChanged(Sensor arg0, int arg1) {
  // TODO Auto-generated method stub
   
 }
 
 @Override
 public void onSensorChanged(SensorEvent event) {
  // TODO Auto-generated method stub
   
  switch(event.sensor.getType()){
  case Sensor.TYPE_ACCELEROMETER:
   for(int i =0; i < 3; i++){
    valuesAccelerometer[i] = event.values[i];
   }
   break;
  case Sensor.TYPE_MAGNETIC_FIELD:
   for(int i =0; i < 3; i++){
    valuesMagneticField[i] = event.values[i];
   }
   break;
  }
   
  boolean success = SensorManager.getRotationMatrix(
       matrixR,
       matrixI,
       valuesAccelerometer,
       valuesMagneticField);
   
  if(success){
   SensorManager.getOrientation(matrixR, matrixValues);
    
   double azimuth = Math.toDegrees(matrixValues[0]);
   double pitch = Math.toDegrees(matrixValues[1]);
   double roll = Math.toDegrees(matrixValues[2]);
    
   readingAzimuth.setText("Azimuth: " + String.valueOf(azimuth));
   readingPitch.setText("Pitch: " + String.valueOf(pitch));
   readingRoll.setText("Roll: " + String.valueOf(roll));
    
   myCompass.update(matrixValues[0]);
  }
   
 }
}

Modify main.xml to add a View of Compass

Cheers Guys!!!!!!!!