使用CardLayout更改JPanel的大小

使用CardLayout更改JPanel的大小

拍摄，像这样，在组件（这里是JLabel而不是JPanel）设置了preferredSize，然后将其放置在使用适当布局的另一个JPanel中，这里是GridBagLayout，默认设置会将组件居中，并使用GridBagLayout添加使用面板将JPanel转换为CardLayout
：：

import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.border.Border;public class MultiSizedPanels {   private static void createAndShowUI() {      final CardLayout cardLayout = new CardLayout();      final JPanel cardHolder = new JPanel(cardLayout);      JLabel[] labels = {         new JLabel("Small Label", SwingConstants.CENTER),         new JLabel("Medium Label", SwingConstants.CENTER),         new JLabel("Large Label", SwingConstants.CENTER)};      for (int i = 0; i < labels.length; i++) {         int padding = 50;         Dimension size = labels[i].getPreferredSize();         size = new Dimension(size.width + 2 * (i + 1) * padding, size.height + 2 * (i + 1) * padding);         labels[i].setPreferredSize(size);         Border lineBorder = BorderFactory.createLineBorder(Color.blue);         labels[i].setBorder(lineBorder);         JPanel containerPanel = new JPanel(new GridBagLayout());         containerPanel.add(labels[i]);         cardHolder.add(containerPanel, String.valueOf(i));      }      JButton nextButton = new JButton("Next");      nextButton.addActionListener(new ActionListener() {         public void actionPerformed(ActionEvent e) { cardLayout.next(cardHolder);         }      });      JPanel btnHolder = new JPanel();      btnHolder.add(nextButton);      Jframe frame = new Jframe("MultiSizedPanels");      frame.getContentPane().add(cardHolder, BorderLayout.CENTER);      frame.getContentPane().add(btnHolder, BorderLayout.SOUTH);      frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);      frame.pack();      frame.setLocationRelativeTo(null);      frame.setVisible(true);   }   public static void main(String[] args) {      java.awt.EventQueue.invokeLater(new Runnable() {         public void run() { createAndShowUI();         }      });   }}