How can I switch between jpanels?

Question

I'm still very new to java programming, so please help me to correct any mistakes I might have overlooked or give tips on how to improve this program. Okay, so a lot of problems have been solved, and now I have a CardLayout, but I still have questions about how I should make my pipes show inside it. When I tried to add in my refresh rate timer and my speed timer, I have problems about how I need to declare and initialize boolean variables. Also, when I compile and run this game, I get files such as `Game$1.class`. Is there a way for me to clean this up, and could someone explain why this happens? Do these have an affect on the finished product? (When the game is compiled and packaged into a JAR.) I want to set playerIsReady to true when the play button is clicked. And from there, when the if statement is true, then switch to a panel that displays the pipes, and start moving the pipe across the screen. Preferably 3 instances of that pipe, each starting at different times, but whatever…

Accepted Answer

The best way to approach this is using a `CardLayout`.

Notes

- A button with an `ActionListener` is far better than a `MouseListener` over a rectangle.

- The button will show focus when the mouse is pointed at it, or the component is tabbed to via the keyboard.

- The button is keyboard accessible.

- The button has facility to support multiple icons built in (e.g. for 'initial look', focused, pressed etc.)

- White space in the GUI is provided around the menu panel and game by adding an `EmptyBorder`

- The button is made larger by setting a margin.

- Adjust margins, borders and preferred size according to need. These sizes were set by me so as not to make the screenshots too large.

- See more tips in the code comments.

Code

Here is the MCTaRE (Minimal Complete Tested and Readable Example) that produced the above screenshots.

```
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.EmptyBorder;

public class PipesGame {

public static void main(String[] args) {
        Runnable r = new Runnable() {
            @Override
            public void run() {
                // the GUI as seen by the user (without frame)
                final CardLayout cl = new CardLayout();
                final JPanel gui = new JPanel(cl);
                // remove if no border is needed
                gui.setBorder(new EmptyBorder(10,10,10,10));

JPanel menu = new JPanel(new GridBagLayout());
                JButton playGame = new JButton("Play!");
                ActionListener playGameListener = new ActionListener() {

@Override
                    public void actionPerformed(ActionEvent e) {
                        cl.show(gui, "game");
                    }
                };
                playGame.addActionListener(playGameListener);
                Insets margin = new Insets(20, 50, 20, 50);
                playGame.setMargin(margin);
                menu.add(playGame);
                gui.add(menu);
                cl.addLayoutComponent(menu, "menu");

JPanel pipes = new Pipes();
                gui.add(pipes);
                cl.addLayoutComponent(pipes, "game");

JFrame f = new JFrame("Pipes Game");
                f.add(gui);
                // Ensures JVM closes after frame(s) closed and
                // all non-daemon threads are finished
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                // See https://stackoverflow.com/a/7143398/418556 for demo.
                f.setLocationByPlatform(true);

// ensures the frame is the minimum size it needs to be
                // in order display the components within it
                f.pack();
                // should be done last, to avoid flickering, moving,
                // resizing artifacts.
                f.setVisible(true);
            }
        };
        // Swing GUIs should be created and updated on the EDT
        // http://docs.oracle.com/javase/tutorial/uiswing/concurrency
        SwingUtilities.invokeLater(r);
    }
}

class Pipes extends JPanel {

Pipes() {
        setBackground(Color.BLACK);
        setForeground(Color.WHITE);
    }

@Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawString("Pipes game appears here..", 170, 80);
    }

@Override 
    public Dimension getPreferredSize() {
        // adjust to need
        return new Dimension(500,150);
    }
}
```

How can I switch between jpanels?

Solution

Problem

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