打印当前时间 sleep

//模拟倒计时
public class TestSleep2 {
    public static void main(String[] args) {
//        打印当前时间
        Date startTime=new Date(System.currentTimeMillis());//获取系统当前时间
        while (true){
            try {
                Thread.sleep(1000);
                System.out.println(new SimpleDateFormat("HH:mm:ss").format(startTime));
//                更新当前时间
                startTime=new Date(System.currentTimeMillis());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    public static void tenDown() throws InterruptedException{
        int num=10;
        while (true){
            Thread.sleep(1000);
            System.out.println(num--);
            if (num<=0){
                break;
            }
        }
    }
}