利用Java怎么编写一个倒计时功能

 import java.util.*; import java.util.concurrent.*;  public class CountDown {  private int limitSec;  public CountDown(int limitSec) throws InterruptedException{   this.limitSec = limitSec;   System.out.println("Count from "+limitSec);   while(limitSec > 0){    System.out.println("remians "+ --limitSec +" s");    TimeUnit.SECONDS.sleep(1); //设置倒计时间隔  }   System.out.println("Time is out");  }  //Test  public static void main(String[] args) throws InterruptedException {   new CountDown(100);   //倒计时起始时间，多少秒 }  }