android之对话框“确定退出吗？”

AlertDialog.Builder builder = new Builder(this);
builder.setMessage("确认退出吗？"); //提示信息
//监听确认
builder.setPositiveButton("确认", new AlertDialog.OnClickListener() {
   @Override
   public void onClick(DialogInterface dialog, int which) {
        dialog.dismiss(); //取消对话框
        System.exit(0); //退出程序
   }
});
//监听取消
builder.setNegativeButton("取消", new AlertDialog.OnClickListener() {
   @Override
   public void onClick(DialogInterface dialog, int which) {
        dialog.dismiss(); //取消对话框
   }
});
//先创建Dialog后show，也可直接show
builder.create().show();