用java 多线程编写一个定时器每隔一秒钟，在控制台打印出当前时间，每行都有注释

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class TimerThread extends Thread {
    private static final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    @Override
    public void run() {
        while (true) { // 循环执行
            try {
                // 获取当前时间
                Calendar calendar = Calendar.getInstance();
                String currentTime = sdf.format(calendar.getTime());
                System.out.println(currentTime); // 打印当前时间
                Thread.sleep(1000); // 线程休眠1秒钟
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        TimerThread timerThread = new TimerThread();
        timerThread.start();
    }
}