彻底退出所有的Acticity

1 ExitApplication.getInstance().addActivity(this);

boolean stata;  //true为退出 ,false为不退出
    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) { 
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            //我在这里用到的是自定义窗口，如果使用默认的，请自行百度。
            CustomDialog.Builder builder = new CustomDialog.Builder(this);
            builder.setTitle("是否退出");
            builder.setPositiveButton("是", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ExitApplication.getInstance().exit(); //重点在这一句
                    stata = true;
                }
            });

            builder.setNegativeButton("不是", new android.content.DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                    stata = false;
                }
            });

            builder.create().show();

        }
        return stata;
    }