Finally, inside the Button's onClickListener, start the new TwitterService. And don't forget to call 'stopSelf()' on th

public class TwitterService extends Service {
  TwitterClient twitterClient = new TwitterClient();  

  TwitterThread twitterThread;

  @Override
  public void onCreate () {
    twitterThread = new TwitterThread ();
    twitterThread.start ();
  }
  @Override
  public IBinder onBind (Intent intent) {
    return null;
  }

  @Override
  public int onStartCommand (Intent intent, int flags, int startId) {
    Message message = Message.obtain ();
    twitterThread.twitterHandler.sendMessage(message);
    return START_REDELIVER_INTENT;
  }




  class TwitterThread extends Thread {
    TwitterHandler twitterHandler;
    @Override
    public void run() {
      Looper.prepare();
      twitterHandler = new TwitterHandler();
      Looper.loop();
    }
  }    

  class TwitterHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
      twitterClient.update();
      stopSelf();

    }
  }
}

public class MainActivity extends Activity {
  Button button;   

  @Override
  public void onCreate(Bundle savedInstanceState) {
    setContentView(R.layout.activity_main);

    button = (Button) findViewById(R.id.update_button);
    button.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v){
        startService (Intent intent);



      }
    });
  }
}