如何使用CardLayout在面板之间切换？

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

JFrame frame = new JFrame("CardLayout Example");
JPanel panel = new JPanel();

CardLayout cardLayout = new CardLayout();
panel.setLayout(cardLayout);

JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
// ...
panel1.setName("Panel 1");
panel2.setName("Panel 2");
// ...

panel.add(panel1, "Panel 1");
panel.add(panel2, "Panel 2");
// ...

JButton button1 = new JButton("Switch to Panel 1");
JButton button2 = new JButton("Switch to Panel 2");
// ...

ActionListener listener = new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        cardLayout.show(panel, e.getActionCommand());
    }
};
button1.addActionListener(listener);
button2.addActionListener(listener);
// ...

frame.add(button1, BorderLayout.NORTH);
frame.add(button2, BorderLayout.SOUTH);
// ...

frame.setSize(400, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);