java - Switching JPanels

So I'm trying to make a basic program to learn more about java, and I'm having trouble switching screens. I wanted to have a display class that I could call in other classes to handle all the panels and such, and then make a class to build each panel. What I'm trying to do at the moment is use a button in my startmenu class to change from one panel to another using a method in the display class.

Here's the code in the startmenu class:

public void actionPerformed(ActionEvent e)
{
    display.switchPanel("Start");


}

And here is my display class:

public class Display 
{

    JFrame frame;


    StartMenu start = new StartMenu();
    MainMenu main = new MainMenu();


    JPanel panel = new JPanel();

    JPanel startPanel = start.createPanel();
    JPanel mainPanel = main.createPanel();



    CardLayout card = new CardLayout();
    BorderLayout border = new BorderLayout();

    public void createDisplay()
    {
        frame = new JFrame("Insert Name");
        frame.setPreferredSize(new Dimension(800,600));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(panel, BorderLayout.CENTER);


        panel.setLayout(border);
        panel.add(startPanel);
        panel.add(mainPanel);

        mainPanel.setVisible(false);
        startPanel.setVisible(true);

        frame.add(panel);
        frame.pack();

        frame.setVisible(true);
        frame.setResizable(false);
    }

    public void switchPanel(String x)
    {
        String p = x;

        if(p.equals("Start"))
        {

            mainPanel.setVisible(true);
            startPanel.setVisible(false);
        }

    }
}

Answer

Use a CardLayout, it's what it's designed for, for example...

public class Display {

    public static final String START_VIEW = "start";
    public static final String MAIN_VIEW = "main";

    JFrame frame;

    StartMenu start = new StartMenu();
    MainMenu main = new MainMenu();


    JPanel panel = new JPanel();

    JPanel startPanel = start.createPanel();
    JPanel mainPanel = main.createPanel();

    CardLayout card = new CardLayout();

    public void createDisplay() {
        frame = new JFrame("Insert Name");
        frame.setPreferredSize(new Dimension(800, 600));

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(panel, BorderLayout.CENTER);

        panel.setLayout(card);
        panel.add(startPanel, START_VIEW);
        panel.add(mainPanel, MAIN_VIEW);

        mainPanel.setVisible(false);
        startPanel.setVisible(true);


        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
        frame.setResizable(false);
    }

    public void switchPanel(String x) {
        card.show(panel, x);
    }
}

Then you might use something like...

public void actionPerformed(ActionEvent e)
{
    display.switchPanel(Display.START_VIEW);
}

to switch between the views

See How to Use CardLayout for more details