Android  TimerTask 的简单应用及注意事项

public class ColTimerTaskActivity extends Activity {    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(); }     }}