单击按钮更改面板尺寸

Question

我有以下代码：

package in.res.num.tapb.ui;

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

class MainClass extends JPanel {
    public MainClass() {
        Registration registration = new Registration();
        ButtonPanel buttonPanel = new ButtonPanel();
        buttonPanel.setRegistration(registration);

        buttonPanel.setBorder(BorderFactory.createTitledBorder("Button Panel"));
        registration.setBorder(BorderFactory.createTitledBorder("Registration Panel"));

        setLayout(new BorderLayout());
        add(registration, BorderLayout.CENTER);
        add(buttonPanel, BorderLayout.SOUTH);
    }

    private static void createAndShowUI() {
        JFrame frame = new JFrame("Registration");
        frame.getContentPane().add(new MainClass());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                createAndShowUI();
            }
        });
    }

    @SuppressWarnings("serial")
    private class ButtonPanel extends JPanel {
        private Registration registration;

        public ButtonPanel() {
            setLayout(new GridLayout(1, 0, 10, 0));     
            for (final String keyText : Registration.KEY_TEXTS) {
                JButton btn = new JButton(keyText);
                btn.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent e) {
                        if (registration != null) {
                            registration.swapView(keyText);
                        }
                    }
                });
                add(btn);
            }
        }

        public void setRegistration(Registration registration) {
            this.registration = registration;
        }
    }

    private static class Registration extends JPanel {
        private static final Dimension PREF_SIZE = new Dimension(450, 300);
        public static final String USER_AGREEMENT = "User Agreement";
        public static final String USER_INFO = "User Information";
        public static final String ENROLLMENT = "Enrollment";
        public static final String[] KEY_TEXTS = { USER_AGREEMENT, USER_INFO, ENROLLMENT };
        private CardLayout cardlayout = new CardLayout();
        private JPanel cards = new JPanel(cardlayout);

        public Registration() {
            cards.add(createUserAgreePanel(), USER_AGREEMENT);
            cards.add(createUserInfoPanel(), USER_INFO);
            cards.add(createEnrollmentPanel(), ENROLLMENT);
            setLayout(new BorderLayout());
            add(cards, BorderLayout.CENTER);
        }



        private JPanel createEnrollmentPanel() {
            JPanel enrol = new JPanel();
            enrol.setSize(new Dimension(400, 200));
            enrol.add(new JLabel("Enrollment"));
            return enrol;
        }

        private JPanel createUserAgreePanel() {
            JPanel userAgree = new JPanel();
            userAgree.setSize(new Dimension(200, 300));
            userAgree.add(new JLabel("User Agreement"));
            return userAgree;
        }

        private JPanel createUserInfoPanel() {
            JPanel userInfo = new JPanel();
            userInfo.setSize(new Dimension(300, 400));
            userInfo.add(new JLabel("User Information"));
            return userInfo;
        }

        public void swapView(String key) {
            cardlayout.show(cards, key);
        }

    }

}

如您所见，我要在单击按钮时更改大小。可能吗？上面的代码不起作用，我的意思是大小没有改变。如何动态更改尺寸？

感谢致敬。编辑：

交换选择一个JList行的面板。

    getChoicesList().addListSelectionListener(new ListSelectionListener() {

        @Override
        public void valueChanged(ListSelectionEvent listSelectionEvent) {
            getViewPanel().changeView(getChoicesList().getSelectedIndex());
            getChoicePanel().changeView(Constants.PanelInfo.valueOf(getEngine().getChoiceList().get(getChoicesList().getSelectedIndex()).getEnumName()).getDimensionForScrollPaneOfChoicePanel());
            ((MainFrame) getTopLevelAncestor()).pack();
        }
    });

ViewPanel＃changeView（），这将交换面板：

public void changeView(int index) {
    removeAll();
    getPanels().get(index).setPreferredSize(Constants.PanelInfo.valueOf(getEngine().getChoiceList().get(index).getEnumName()).getDimensionForViewPanel());
    add(getPanels().get(index));
}

Answer 1

使用布局管理器时，永远不要使用setSize（）。布局管理器的工作是确定大小。您可以通过设置指定的大小或最小或最大大小来向布局管理器提供提示。但是，不建议您执行此操作，因为组件和面板应以其首选尺寸显示，该尺寸由您使用的布局管理器确定。如果您确实覆盖了大小，则代码应为：

// enrol.setSize(new Dimension(400, 200));
enrol.setPreferredSize(new Dimension(400, 200));

但是，这仍然无法按您想要的方式工作，因为CardLayout的工作是确定使用CardLayout添加到面板中的所有面板的最大尺寸。因此，当您从一个面板交换到另一个面板时，不会得到每个单独面板的大小。对于用户而言，这是更好的体验，因为用户不想每次单击按钮时都看到帧大小不断变化。

如果您确实希望每次单击按钮时都具有帧更改大小，则基本代码为：

mainPanel.remove(oldPanel);
mainPanel.add(newPanel);
frame.pack();

然后，主面板的布局管理器将观察新添加的面板的首选大小。