Calling a Service from Activity in Android

public class serv extends Service {
    private static final String TAG = "MyService";   
    AlertDialog alertDialog
    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }
     public void onCreate() {
          Toast.makeText(getApplicationContext(), "My Service Created",Toast.LENGTH_LONG).show();
         }
    @Override   
    public void onDestroy() {   
               Toast.makeText(this, "My Service Stopped",Toast.LENGTH_LONG).show();
               Log.d(TAG, "onDestroy");
               //player.stop();
        }   
    @Override
    public void onStart(Intent intent, int startid) {   
              Toast.makeText(this, "My Service Started",Toast.LENGTH_LONG).show();
              Log.d(TAG, "onStart");       
              //player.start();   
        }
}

    public class MainActivity extends Activity {
    private static final String TAG = "ServicesDemo";
    Button buttonStart, buttonStop; 
    PendingIntent pendingIntent;
   
    @Override
    public void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
              Intent i;
              i=new Intent(MainActivity.this,serv.class);
              startService(i);
}}