18.Android 程序退出，关闭所有的a…

package com.back.util;
import java.util.LinkedList;
 import java.util.List;import android.app.Activity;
 import android.app.Application;public class MyApplication extends Application {
  
  private List activityList=new LinkedList();
     private static MyApplication instance;
     private MyApplication(){}
    
     //单例模式中获取唯一的MyApplication 实例
     public static MyApplication getInstance()
     {
      if(null==instance)
      {
       instance=new MyApplication();
      }
      return instance;
        
     }
    
     //添加Activity 到容器中
     public void addActivity(Activity activity)
     {
      activityList.add(activity);
     }
    
     //遍历所有的activity并finish
     public void exit(){
      
      for(Activity activity:activityList)
      {
       activity.finish();
      }
      
      System.exit(0);
     }
    
     }