Android 动态的显示时间

public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.main);     textView=(TextView) findViewById(R.id.time);       handler = new Handler() {         public void handleMessage(Message msg) {           textView.setText((String)msg.obj);         }       };     new Thread(this).start();   }   @Override   public void run() {     // TODO Auto-generated method stub     try {       while(true){         SimpleDateFormat sdf=new SimpleDateFormat("yyyy年MM月dd日  HH:mm:ss");         String str=sdf.format(new Date());         handler.sendMessage(handler.obtainMessage(100,str));         Thread.sleep(1000);       }     } catch (InterruptedException e) {       // TODO Auto-generated catch block       e.printStackTrace();     }   }