线程休眠 sleep

package state;

import java.text.SimpleDateFormat;
import java.util.Date;

public class TestSleep {

    public static void main(String[] args) {
        //持续打印系统当前时间
        Date startTime = new Date(System.currentTimeMillis());//获取系统当前时间
        while(true){
            System.out.println(new SimpleDateFormat("HH:mm:ss").format(startTime));
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            startTime = new Date(System.currentTimeMillis());//更新当前时间
        }

    }

    //模拟倒计时方法
    public static void tenDown() throws InterruptedException {
        int num = 10;
        while(true){
            Thread.sleep(1000);
            System.out.println(num--);
            if(num<=0){
                break;
            }
        }
    }
}