How can I replace one JPanel with another JPanel at the same position?
I have a JFrame with four frames. After this step, I want to replace one panel with another in the same position. My method of switching them is as follows (an object this
is a class that extends JFrame
):
public void switchPanel(){
mainPanel.remove(introPanel);
mainPanel.add(questionPanel);
this.repaint();
}
The original window creation looks like this:
mainPanel.add(titlePanel);
mainPanel.add(sidePanel);
mainPanel.add(introPanel);
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You're asking:
How can I replace one JPanel with another JPanel at the same position?
Very easy: use CardLayout as this tool was created for this very situation.
If you had the following constants:
public static final String INTRO_PANEL = "intro panel";
public static final String QUESTION_PANEL = "question panel";
and added your JPanel like so
mainPanel.setLayout(cardLayout);
mainPanel.add(introPanel, INTRO_PANEL);
mainPanel.add(questionPanel, QUESTION_PANEL);
cardLayout.show(mainPanel, INTRO_PANEL);
Then you can exchange JPanels for:
cardLayout.show(mainPanel, QUESTION_PANEL);
would be all that was needed to show the swap, assuming QUESTION_PANEL is the String constant that was used when adding the questionnaire to mainPanel and that mainPanel is using CardLayout.
For example:
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.*;
public class SwapPanels extends JPanel {
public static final String INTRO_PANEL = "intro panel";
public static final String QUESTION_PANEL = "question panel";
private static final int PREF_W = 500;
private static final int PREF_H = 400;
private CardLayout cardLayout = new CardLayout();
private JPanel introPanel;
private JPanel questionPanel;
private Random random = new Random();
public SwapPanels() {
introPanel = createPanel("Introduction");
questionPanel = createPanel("Question");
setLayout(cardLayout);
add(introPanel, INTRO_PANEL);
add(questionPanel, QUESTION_PANEL);
int delay = 3 * 1000; // show intro for 3 seconds
new Timer(delay, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
cardLayout.show(SwapPanels.this, QUESTION_PANEL);
((Timer) e.getSource()).stop();
}
}).start();
}
private JPanel createPanel(String title) {
int rgb = random.nextInt();
Color color = new Color(rgb);
JPanel panel = new JPanel(new GridBagLayout());
panel.setBorder(BorderFactory.createLineBorder(color, 60));
panel.add(new JLabel(title));
return panel;
}
@Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
SwapPanels mainPanel = new SwapPanels();
JFrame frame = new JFrame("SwapPanels");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
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