在JPanel之间切换（隐藏/显示）

Question

I have two JPanels that sit on top of one another. The 'top' panel holds many widgets (JButtons, JTextFields, etc.). One of the buttons will initiate an action to display a number of images.

These images are displayed on the other JPanel. So, when this button is clicked, I want to hide the control panel and display the images panel. Sounds pretty simple.

Here is the code (I've omitted a lot of stuff that I don't think is relevant). In the constructor, if I switch which panel is visible when the app launches, it looks fine either way. When I click the button, I should go from my dark gray control panel to my blue images panel. Except that what happens is my dark gray control panel becomes an empty white panel. Any ideas?

public GUI() {

   JFrame frame = new JFrame();
   ...
   JPanel imagesPanel = new ImagesPanel();
   imagesPanel.setBackground(Color.BLUE);
   imagesPanel.setVisible(false);
   frame.getContentPane().add(imagesPanel, BorderLayout.CENTER);

   // make a JPanel to hold all of the buttons and text fields
   JPanel imagesPanel = new ImagesPanel();
   controlPanel.setBackground(Color.DARK_GRAY);
   controlPanel.setVisible(true);
   frame.getContentPane().add(controlPanel, BorderLayout.CENTER);
   ...

    JButton btnDisplayImages = new JButton("Display Images");
    btnDisplayImages.setPreferredSize(standardButtonSize);
    btnDisplayImages.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            imagesPanel.setVisible(true);
            controlPanel.setVisible(false);
            frame.repaint();
            frame.setVisible(true);
        }
    });   
    // button added to control panel

    ...
}

Answer 1

Use CardLayout. (docs.oracle.com/javase/tutorial/uiswing/layout/card.html)

final String IMAGES_PANEL = "Images Panel";
final String CONTROL_PANEL = "Control Panel";
CardLayout cardLayout;
JPanel cards;

//Where the components controlled by the CardLayout are initialized:
//Create the "cards".
JPanel card1 = new JPanel();
...
JPanel card2 = new JPanel();
...

//Create the panel that contains the "cards".
cardLayout = new CardLayout();
cards = new JPanel(cardLayout);
cards.add(card1, IMAGES_PANEL);
cards.add(card2, CONTROL_PANEL);
...
//Show images panel
cardLayout.show(cards,IMAGES_PANEL);
...
//Show control panel
cardLayout.show(cards, CONTROL_PANEL);