求助！！在面板上倒计时功能显示不出来

import javax.swing.*;
import java.awt.*;
import java.text.SimpleDateFormat;
import java.util.Date;

public class CountDown extends JFrame {//窗体类,继承JFrame
    JLabel timer, count;
    public CountDown() {
        //Container c = getContentPane();//得到内容面板
        JFrame jFrame = new JFrame("倒计时");
        timer = new JLabel("时钟", JLabel.CENTER);
        count = new JLabel("倒计时", JLabel.CENTER);
        jFrame.add(timer);//将timer添加到内容面板中
        jFrame.add(count);
        timer.setFont(new Font("宋体", Font.BOLD, 50)); //设置字体
        count.setFont(new Font("宋体", Font.BOLD, 50)); //设置字体
        jFrame.setSize(1100, 500);
        jFrame.setVisible(true);
        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//关闭按钮

    }

    public static void main(String args[]) {
        CountDown countDown = new CountDown();
        new MyTimer1(countDown).start();//创建线程对象，并启动
    }
}

class MyTimer1 extends Thread {//线程类,继承Thread类
    CountDown countDown;

    MyTimer1(CountDown countDown) {
        this.countDown = countDown;
    }

    public void run() {
        while (true) {
            SimpleDateFormat dateformat = new SimpleDateFormat("yyyy" + "年" + "MM" + "月" + "dd" + "日" + "HH" + "时" + "mm" + "分" + "ss" + "秒");
            String s = dateformat.format(new Date());

            Date end = new Date(2022 - 12 - 10);
            long time = (end.getTime() - 1 - System.currentTimeMillis()) / 1000;
            if (time <= 0) {
                break;
            }
            long day = time / 3600 * 24;
            long hour = time / 3600;
            long minute = (time - hour * 3600) / 60;
            long seconds = time - hour * 3600 - minute * 60;
            StringBuilder stringBuilder = new StringBuilder();

            countDown.timer.setText("现在时间:" + s);//将标签内容设置为可格式化文本

            stringBuilder.append("距离北京2022年冬奥会开幕还有").append(day).append("天").append(hour).append("时").append(minute).append("分").append(seconds).append("秒");
            countDown.count.setText(stringBuilder.toString());

            try {
                Thread.sleep(1000);//休眠1秒钟时间
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

你都没有给控件设置坐标啊
先别管计时了，你随便往label里写几个字，好歹能显示这个label再说改变字的问题