使用計時器來更新畫面

在Android官方網站上，提到如何利用計時功能來更新人機介面的內容。http://developer.android.com/resources/articles/timed-ui-updates.html
以下是修改自該篇文章的完整範例：

package com.example.update;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;

public class UpdateUIActivity extends Activity {
    private long mStartTime;
    TextView mTimeLabel;


 /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mTimeLabel = (TextView) findViewById(R.id.timer);
        mStartTime = System.currentTimeMillis(); 
        mHandler.removeCallbacks(mUpdateTimeTask); 
        mHandler.postDelayed(mUpdateTimeTask, 100); 
    }
    private Handler mHandler = new Handler(); 
    
    
    private Runnable mUpdateTimeTask = new Runnable() { 
        public void run() { 
            final long start = mStartTime; 
            long millis = System.currentTimeMillis() - start; 
            int seconds = (int) (millis / 1000); 
            int minutes = seconds / 60; 
            seconds     = seconds % 60; 
      
            if (seconds < 10) { 
                mTimeLabel.setText("" + minutes + ":0" + seconds); 
            } else { 
                mTimeLabel.setText("" + minutes + ":" + seconds);             
            } 
            mHandler.postDelayed(mUpdateTimeTask, 100); 
          
        } 
     };
}