Android  TimerTask 的简单应用及注意事项

public class ColTimerTaskActivity extends Activity {
  /** Called when the activity is first created. */
 
 private final String TAG = "ColTimerTaskActivity";
 private final int EVENT_LOCK_WINDOW = 0x100;
 
 private TextView textView;
 private Handler mHandler;
 private Timer mTimer;
 private MyTimerTask mTimerTask;
 
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    
    textView = (TextView)findViewById(R.id.textview);
    
    mHandler = new Handler(){
     public void handleMessage(Message message){
     Log.i(TAG, "message what = " + message.what);
     if (message.what == 0x100){
      lockWindow();
     }
     
     }
    };
    
    mTimer = new Timer(true);
    
    resumeWindow();
    
    StartLockWindowTimer();
  }
  
  public boolean onTouchEvent(MotionEvent event)
  {
   // TODO Auto-generated method stub
   resumeWindow();
   StartLockWindowTimer();
   
   return super.onTouchEvent(event);
  }
  
  public void resumeWindow(){
   textView.setText("main window");
 
  }
  
  public void lockWindow(){
   textView.setText("lock window");
  }
  
  public void StartLockWindowTimer(){
   if (mTimer != null){
   if (mTimerTask != null){
    mTimerTask.cancel(); //将原任务从队列中移除
   }
   
   
   mTimerTask = new MyTimerTask(); // 新建一个任务   
   mTimer.schedule(mTimerTask, 3000);
   }
  }
  
  class MyTimerTask extends TimerTask{
 @Override
 public void run() {
  // TODO Auto-generated method stub
  Log.i(TAG, "run...");
  Message msg = mHandler.obtainMessage(EVENT_LOCK_WINDOW);
  msg.sendToTarget();
 }
   
  }
}

 if (mTimerTask != null){
      mTimerTask.cancel(); //将原任务从队列中移除
   }

 mTimerTask = new MyTimerTask(); // 新建一个任务