将下面SysApplication这个类复制到工程里面，然后在每个Acitivity的oncreate方法里面通过SysApplication.getInstance().addActivity(this); 添加当前Acitivity到ancivitylist里面去，最后在想退出的时候调用SysApplication.getInstance().exit();可直接关闭所有的Acitivity并退出应用程序。

package com.example.Emotional.util; import java.util.LinkedList; import java.util.List; import android.app.Activity; import android.app.Application;   /** * * 类名称：SysApplication   * 类描述：   退出整个应用程序的类* 创建时间：2014-4-25 下午1:58:00   * 修改备注：   * @version    * */ public class SysApplication extends Application {          private List
     
       mList = new LinkedList
      
       ();     private static SysApplication instance;       private SysApplication() {}     public synchronized static SysApplication getInstance() {         if (null == instance) {             instance = new SysApplication();         }         return instance;     }     // add Activity      public void addActivity(Activity activity) {         mList.add(activity);     }       public void exit() {         try {             for (Activity activity : mList) {                 if (activity != null)                     activity.finish();             }         } catch (Exception e) {             e.printStackTrace();         } finally {             System.exit(0);         }     }     public void onLowMemory() {         super.onLowMemory();             System.gc();     }  }
      
     

在硬退出按钮点击时

//点击硬退出按钮    public void clickQuitDialog() {                      AlertDialog.Builder builder = new Builder(FirstActivity.this);             builder.setMessage("确定要退出吗?");             //          builder.setTitle("提示");             builder.setPositiveButton("确认",new android.content.DialogInterface.OnClickListener() {                     @Override                     public void onClick(DialogInterface dialog, int which) {                         dialog.dismiss(); //                        FirstActivity.this.finish(); //                        System.exit(0);                        SysApplication.getInstance().exit();                    }                 });             builder.setNegativeButton("取消",new android.content.DialogInterface.OnClickListener() {                     @Override                     public void onClick(DialogInterface dialog, int which) {                         dialog.dismiss();                     }                 });             builder.create().show();         }              @Override     public boolean onKeyDown(int keyCode, KeyEvent event) {                          //event.getRepeatCount() == 0 防止重复点击            if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {                 clickQuitDialog();                 return false;             }             return false;         }