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(); 
    } 
  }