How to Switch JPanels within a JFrame using CardLayout?

Switching JPanels within a JFrame

Question:
I'm new to Java components and having trouble switching JPanels inside a JFrame. When I call gameOn(), the Frame surface becomes blank without displaying the game panel. How can I fix this?

Answer:

Instead of adding and removing components, it's recommended to use a CardLayout. Here's how:

1. Create a CardLayout object and a JPanel using it:

   <code class="java">CardLayout cardLayout = new CardLayout();
   JPanel mainPanel = new JPanel(cardLayout);</code>

2. Add the menu and game panels to mainPanel:

   <code class="java">MenuPanel menu = new MenuPanel();
   GamePanel game = new GamePanel();
   mainPanel.add(menu, "menu");
   mainPanel.add(game, "game");</code>

3. In the gameOn() method, simply show the game panel using cardLayout without adding or removing any components:

   <code class="java">public void gameOn() {
       cardLayout.show(mainPanel, "game");
   }</code>

4. When gameOn() is called, the menu panel will be hidden behind the game panel.

Example:

<code class="java">import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

class GameFrame extends JFrame implements ActionListener {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new GameFrame().setVisible(true));
    }

    private CardLayout cardLayout;
    private JPanel mainPanel;
    private MenuPanel menuPanel;
    private GamePanel gamePanel;

    public GameFrame() {
        cardLayout = new CardLayout();
        mainPanel = new JPanel(cardLayout);

        menuPanel = new MenuPanel();
        mainPanel.add(menuPanel, "menu");

        gamePanel = new GamePanel();
        mainPanel.add(gamePanel, "game");

        JButton goGameButton = new JButton("Go to Game");
        goGameButton.addActionListener(this);

        add(mainPanel);
        add(goGameButton, BorderLayout.SOUTH);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setLocationRelativeTo(null);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        cardLayout.show(mainPanel, "game");
    }

}

class MenuPanel extends JPanel {

    public MenuPanel() {
        setBackground(Color.GREEN);
        add(new JLabel("Menu"));
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(300, 300);
    }
}

class GamePanel extends JPanel {

    public GamePanel() {
        setBackground(Color.BLUE);
        add(new JLabel("Game"));
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(300, 300);
    }
}</code>

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