使用java编写一个计时器

以下是一个简单的计时器示例，使用Java编写：

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

public class TimerExample extends JFrame {
    private Timer timer;
    private int seconds = 0;
    private JLabel label;

    public TimerExample() {
        setTitle("计时器");
        setSize(300, 200);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        label = new JLabel("计时器：00:00:00");
        label.setFont(new Font("Arial", Font.BOLD, 24));
        label.setHorizontalAlignment(SwingConstants.CENTER);
        add(label, BorderLayout.CENTER);

        JButton startButton = new JButton("开始");
        startButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                start();
            }
        });
        add(startButton, BorderLayout.NORTH);

        JButton stopButton = new JButton("停止");
        stopButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                stop();
            }
        });
        add(stopButton, BorderLayout.SOUTH);
    }

    private void start() {
        timer = new Timer(1000, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                seconds++;
                int hour = seconds / 3600;
                int minute = (seconds % 3600) / 60;
                int second = seconds % 60;
                String time = String.format("%02d:%02d:%02d", hour, minute, second);
                label.setText("计时器：" + time);
            }
        });
        timer.start();
    }

    private void stop() {
        if (timer != null) {
            timer.stop();
            timer = null;
        }
        seconds = 0;
        label.setText("计时器：00:00:00");
    }

    public static void main(String[] args) {
        TimerExample timerExample = new TimerExample();
        timerExample.setVisible(true);
    }
}

该程序创建一个带有“开始”和“停止”按钮的窗口，当用户单击“开始”按钮时，计时器将开始计时，并且计时器标签将更新以显示经过的时间。当用户单击“停止”按钮时，计时器将停止并将时间重置为零。