android两次按返回键退出程序实现

android两次按返回键退出程序实现  

private static Boolean isExit = false;  

    private static Boolean hasTask = false;  

    Timer tExit = new Timer();  

    TimerTask task = new TimerTask() {  

           

        @Override  

        public void run() {  

            isExit = false;  

            hasTask = true;  

        }  

    };  

  

  

public boolean onKeyDown(int keyCode, KeyEvent event) {