你问:
如何在同一位置替换一个JPanel为另一个JPanel?
非常简单:使用
CardLayout,因为这个工具就是为这种情况而建立的。
如果你有以下常量:
public static final String INTRO_PANEL = "intro panel";
public static final String QUESTION_PANEL = "question panel";
并且像这样添加您的 JPanel:
mainPanel.setLayout(cardLayout);
mainPanel.add(introPanel, INTRO_PANEL);
mainPanel.add(questionPanel, QUESTION_PANEL);
cardLayout.show(mainPanel, INTRO_PANEL);
那么您可以使用以下方法交换JPanels:
cardLayout.show(mainPanel, QUESTION_PANEL);
假设QUESTION_PANEL是一个字符串常量,用于将questionPanel添加到mainPanel,并且mainPanel使用CardLayout,则只需执行上述操作即可显示交换。例如:
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;
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();
}
});
}
}