Thread sleep()休眠就是讓線程進入休眠狀態TIMED_WAITING,sleep("毫秒數")，當休眠時間到了之後繼續線程。當然也可以用中斷線程interrupt()來中斷線程休眠。判斷線程是否休眠if(ts.getstate()==state.TIMED_WAITING)

利用線程休眠來做秒表

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;

public class Time extends JFrame{
    public Time(){
        setTitle("秒表");
 

        setSize(300,300);
        setVisible(true);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        JLabel label=new JLabel("00:000");
        Font f=new Font("微軟雅黑",Font.BOLD,56);
        label.setFont(f);
        label.setBounds(30,10,250,100);
        add(label);
        JButton bt=new JButton("開始");
 
        bt.addActionListener(new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent e) {
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        long s=0,ms,start=System.currentTimeMillis();//獲取系統當前時間
 
                        while (true){
                            ms=System.currentTimeMillis()-start;
                            s=ms/1000;ms=ms%1000;
                            String ss=s+"",sms=ms+"";
                            if (s<10) ss="0"+ss;
                            if (ms<10)  sms="00"+ms;
                            else if (ms<100) sms="0"+ms;
                            String str=ss+":"+sms;
                            label.setText(str);
                            // System.out.println(str);
                            try {
                                Thread.sleep(10);//休眠10毫秒
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }).start();
            }
        });
        bt.setBounds(30,200,80,30);
        add(bt);
        JButton bt1=new JButton("暫停");
        bt1.setBounds(150,200,80,30);
        add(bt1);
        JLabel b=new JLabel();
        add(b);

    }
    public static void main(String[] args){
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Time();
            }
        });
    }
}

Thread sleep()休眠