Android學習-- 銷毀activity時注意關閉線程

在Activity開啟的子線程並不會自動隨Activity的destroy而關閉，所以必須手動去關閉子線程或者通過boolean的方式讓子線程結束運行。開啟的子線程有for循環的要更加注意。

package com.lsw; 

import android.app.Activity;  
import android.os.Bundle;  
import android.os.Handler;  
import android.os.Message;
import android.util.Log;  
public class ThreadDemoActivity extends Activity {  
    private static final String TAG = "ThreadDemo";  
    private int count = 0;  
    private Handler mHandler =  new MyHandler();  
    boolean stopThread=false;
      
    private Runnable mRunnable = new Runnable() {
          
        public void run() {
            
            while (!stopThread)
            {
                count++;  
                try
                {
                    Thread.sleep(2000);
                }
                catch (InterruptedException e)
                {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                
                //雖然Message的構造函數是public的，但是最好是使用Message.obtain( )或Handler.obtainMessage( )函數來獲取Message對象，因為Message的實現中包含了回收再利用的機制，可以提供效率。
                Message message=mHandler.obtainMessage();
                message.what=0;
                message.obj=count;
                mHandler.sendMessage(message);
            }
        }  
    };  
    
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);   
        //開啟子線程
        new Thread(mRunnable).start();
    }  
     
    protected void onDestroy() {
        System.out.println("-----------onDestroy------");
        stopThread=true;
        super.onDestroy();
    };   
    
    class MyHandler extends Handler{
        
        @Override
        public void handleMessage(Message msg)
        {
        // TODO Auto-generated method stub
            Log.e(TAG, Thread.currentThread().getName() + " " +msg.obj);  
            setTitle("" +msg.obj);  
        }
    }
    
}