android退出应用：弹出对话框退出应用

（1）定义栈，写一个Exitactivity 类，利用单例模式管理Activity，在每个在
Activity 的onCreate()方法中调用Exitactivity.getInstance().addActivity(this)方法,在退
出时调用Exitactivity.getInstance().exit()方法，就可以完全退出应用程序了。这个主要建立了一个对话框退出activity

（2）Exitactivity类：package com.liuzuyi.exit;

import java.util.LinkedList;
import java.util.List;

import android.app.Activity;
import android.app.Application;

public class Exitactivity extends Application {

private List<Activity> activityList=new LinkedList<Activity>();

private static Exitactivity instance;

private Exitactivity()
{
}
//单例模式中获取唯一的ExitApplication 实例
public static Exitactivity getInstance()
{
if(null == instance)
{
instance = new Exitactivity();
}
return instance;

}
//添加Activity 到容器中
public void addActivity(Activity activity)
{
activityList.add(activity);
}
//遍历所有Activity 并finish

public void exit()
{

for(Activity activity:activityList)
{
activity.finish();
}

System.exit(0);

}
}



MainActivity:

package com.liuzuyi.exit;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {
private Button next;
private Button exit;
int i = 0;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

next=(Button)findViewById(R.id.button2);
exit=(Button)findViewById(R.id.button1);

next.setOnClickListener(l);

exit.setOnClickListener(ll);
Exitactivity.getInstance().addActivity(this);
}
OnClickListener l = new OnClickListener() {

public void onClick(View v) {
Intent intent=new Intent(MainActivity.this,TwoActivity.class);
startActivity(intent);
}
};
OnClickListener ll = new OnClickListener() {

@Override
public void onClick(View v) {
builddialog();
}
};
public void builddialog()
{
AlertDialog.Builder ad = new Builder(MainActivity.this) ;
ad.setTitle("退出应用");
ad.setMessage("是否退出应用？");
ad.setPositiveButton("确认", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Exitactivity.getInstance().exit();
} }
);
ad.setNegativeButton("取消", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
ad.create().show();
}

}



其他的两个activity也是同样的，可以参考上面的activity