停止"javax.swing.timer“不会暂停动画

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

public class AnimationExample extends JPanel implements ActionListener {
    private int x = 0;
    private int y = 100;
    private int deltaX = 1;
    private Timer timer;

    public AnimationExample() {
        timer = new Timer(10, this);
        timer.start();
    }

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.RED);
        g.fillOval(x, y, 50, 50);
    }

    public void actionPerformed(ActionEvent e) {
        if (x >= getWidth() - 50 || x <= 0) {
            deltaX = -deltaX;
        }
        x += deltaX;
        repaint();
    }

    public void pauseAnimation() {
        timer.stop();
    }

    public void resumeAnimation() {
        timer.start();
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Animation Example");
        AnimationExample animation = new AnimationExample();
        frame.add(animation);
        frame.setSize(400, 200);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

        // 暂停动画
        animation.pauseAnimation();

        // 一段时间后恢复动画
        try {
            Thread.sleep(3000);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }
        animation.resumeAnimation();
    }
}