public class Countdown2 {
    private volatile int lin;
    private int curSec;
    public Countdown2(int lin) throws InterruptedException{
        /*记录倒计时时间*/
        this.lin = lin;
        /*记录倒计时当下时间*/
        this.curSec = lin;
        System.out.println("最后倒计时： " + lin + "秒");

        /*此处存在缺陷，需要手动创建线程池*/
        ScheduledExecutorService exec = Executors.newScheduledThreadPool(1);
        exec.scheduleAtFixedRate(new Task(),0,1,TimeUnit.SECONDS );
        //暂停本线程
        TimeUnit.SECONDS.sleep(lin);
        exec.shutdown();
        System.out.println("Game over!!");
    }
    private class Task implements Runnable{
        @Override
        public void run() {
            System.out.println("倒计时： " + --curSec + "秒");
        }
    }

    public static void main(String[] args) throws InterruptedException{
        new Countdown2(20);
    }
}