java - How to switch JPanels in a JFrame from within the panel?

Question

So, I'm trying to make a basic functional menu for a simple game. I tried to do this by creating 2 JPanels, one for the actual game, and another for my menu.

What I'm trying to do is have a button on my Menu panel that when pressed, switches the JPanel being displayed in the parent JFrame from that of the menu to that of the actual game.

Here is my code:

class Menu extends JPanel
{
   public Menu()
   {
      JButton startButton = new JButton("Start!");
      startButton.addActionListener(new Listener());
      add(startButton);
   }

   private class Listener implements ActionListener
   {
      public void actionPerformed(ActionEvent e)
      {     
         Container container = getParent();
         Container previous = container;
         System.out.println(getParent());
         while (container != null)
         {
            previous = container;
            container = container.getParent();
         }
         previous.setContentPane(new GamePanel());      
      }
   }
}

As you can see, I created a Listener for my start button. Inside the listener, I used a while loop to get to the JFrame, via the getParent() method. The program is getting the JFrame object, however it's not letting me call the setContentPane method...

Does anyone know how to get this to work, or a better way to switch back and forth between a menu and game?

Answer 1

Like so :

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class CardLayoutDemo extends JFrame {

    public final String YELLOW_PAGE = "yellow page";
    public final String RED_PAGE = "red page";
    private final CardLayout cLayout;
    private final JPanel mainPane;
    boolean isRedPaneVisible;

    public CardLayoutDemo(){

        setTitle("Card Layout Demo");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);

        mainPane = new JPanel();
        mainPane.setPreferredSize(new Dimension(250,150));
        cLayout = new CardLayout();
        mainPane.setLayout(cLayout);

        JPanel yellowPane = new JPanel();
        yellowPane.setBackground(Color.YELLOW);
        JPanel redPane = new JPanel();
        redPane.setBackground(Color.RED);

        mainPane.add(YELLOW_PAGE, yellowPane);
        mainPane.add(RED_PAGE, redPane);
        showRedPane();

        JButton button = new JButton("Switch Panes");
        button.addActionListener(e -> switchPanes() );

        setLayout(new BorderLayout());
        add(mainPane,BorderLayout.CENTER);
        add(button,BorderLayout.SOUTH);
        pack();
        setVisible(true);
    }

    void switchPanes() {
        if (isRedPaneVisible) {showYelloPane();}
        else { showRedPane();}
    }

    void showRedPane() {
        cLayout.show(mainPane, RED_PAGE);
        isRedPaneVisible = true;
    }

    void showYelloPane() {
        cLayout.show(mainPane, YELLOW_PAGE);
        isRedPaneVisible = false;
    }

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

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