Card Layout Panel Call With Button

package wan.dev.sample.cardlayout;

import java.awt.CardLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

import javax.swing.JLabel;

public class HowToUseCardLayout {

    private JFrame frame;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    HowToUseCardLayout window = new HowToUseCardLayout();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public HowToUseCardLayout() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 688, 358);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(null);

        JPanel mainPanel = new JPanel();
        mainPanel.setBounds(0, 0, 672, 260);
        frame.getContentPane().add(mainPanel);
        mainPanel.setLayout(new CardLayout(0, 0));

                JPanel PrePanel = new JPanel();
                mainPanel.add(PrePanel, "name_246268073832057");
                PrePanel.setLayout(null);

                        JLabel lblPanel_1 = new JLabel("Pre Panel");
                        lblPanel_1.setBounds(280, 115, 57, 20);
                        PrePanel.add(lblPanel_1);

        JPanel panelOne = new JPanel();
        mainPanel.add(panelOne, "name_246268067657434");
        panelOne.setLayout(null);

        JLabel lblPanel = new JLabel("panel 1");
        lblPanel.setBounds(279, 118, 46, 14);
        panelOne.add(lblPanel);

        JButton btnPan1 = new JButton("Call PanelOne");
        btnPan1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

                CardLayout card = (CardLayout) mainPanel.getLayout();
                card.show(mainPanel, "PanelOne");

            }
        });
        btnPan1.setBounds(262, 286, 144, 23);
        frame.getContentPane().add(btnPan1);
    }
}