使用java 编写一个模拟龟兔赛跑的窗体应用程序，绘制不同颜色的两个圆分别代表乌龟和兔子，设置一个按钮，单击按键后，龟兔开始赛跑。

以下是使用Java编写的模拟龟兔赛跑的窗体应用程序的示例代码：

import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.util.Random;

public class TurtleRabbitRace extends JPanel implements ActionListener {
    private static final long serialVersionUID = 1L;
    private JButton startButton;
    private int turtleX, rabbitX;
    private final int Y = 150;
    private final int RADIUS = 20;
    private final int FINISH_LINE = 500;
    private final int DELAY_TIME = 50;
    private final int SLEEP_TIME = 100;
    private final int SLOW_DOWN_TIME = 200;
    private Random random = new Random();

    public TurtleRabbitRace() {
        // Initialize the window
        JFrame frame = new JFrame("Turtle Rabbit Race");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(600, 300);
        frame.setLocationRelativeTo(null);

        // Initialize the start button
        startButton = new JButton("Start");
        startButton.addActionListener(this);

        // Add components to the window
        frame.add(this);
        frame.add(startButton, "South");

        // Show the window
        frame.setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == startButton) {
            // Start the race
            turtleX = 0;
            rabbitX = 0;
            repaint();
            try {
                Thread.sleep(SLEEP_TIME);
            } catch (InterruptedException ex) {}
            while (turtleX < FINISH_LINE && rabbitX < FINISH_LINE) {
                // Calculate the distance that the turtle and the rabbit move
                int turtleDistance = random.nextInt(10);
                int rabbitDistance = random.nextInt(100);

                // Move the turtle and the rabbit
                turtleX += turtleDistance;
                rabbitX += rabbitDistance;

                // Slow down the rabbit if it is too fast
                if (rabbitDistance > 50) {
                    try {
                        Thread.sleep(SLOW_DOWN_TIME);
                    } catch (InterruptedException ex) {}
                }

                // Repaint the window
                repaint();
                try {
                    Thread.sleep(DELAY_TIME);
                } catch (InterruptedException ex) {}
            }
        }
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        // Draw the finish line
        g.drawLine(FINISH_LINE, 0, FINISH_LINE, getHeight());

        // Draw the turtle and the rabbit
        g.setColor(Color.GREEN);
        g.fillOval(turtleX, Y, RADIUS, RADIUS);

        g.setColor(Color.RED);
        g.fillOval(rabbitX, Y - 50, RADIUS, RADIUS);
    }

    public static void main(String[] args) {
        new TurtleRabbitRace();
    }
}

这个程序创建了一个窗体应用程序，包含一个绘制龟兔赛跑的面板和一个开始按钮。单击开始按钮后，龟兔开始赛跑。龟兔的移动距离是随机生成的，其中兔子的移动距离比乌龟的移动距离大，但如果兔子移动距离过大，它会被减速。程序会在每次移动后重新绘制龟兔的位置，直到有一只动物到达终点线。