在主窗口中切换JPanel

Question

我有一个应用程序，允许用户选择一个选项，并根据用户选择从组件中删除一个JPanel，添加新的JPanel并重新验证该组件

看到代码：

          if (c != null) {
                contentPane.remove(c);
            }
            c = new AddBookInterface(theLibrary);
            contentPane.add(c);
            contentPane.revalidate();
            break;

c是一个组件

我有几个JPanels，用户可以在它们之间切换，并且开关可以正常工作。但是，当我根据用户选择添加此JPanel时，以后添加的JPanels无法正确加载。是什么原因造成的？

   public class RemoveBookInterface extends JPanel {

private Library theLibrary;

public RemoveBookInterface(Library theLibrary) {
    this.theLibrary = theLibrary;
    setSize(400, 400);
    setLayout(new BorderLayout());
    setVisible(true);
    removeBook(theLibrary);
}

public void removeBook(Library theLibrary) {
    // prompt user for book id of book to remove
    Long ID = Long
            .parseLong(JOptionPane
                    .showInputDialog("Enter the library book ID for the book you want to remove"));
    try {
        // get library book info and store it to display in message
        LibraryBook lb = theLibrary.getInventory().findLibraryBook(ID);
        // remove book
        theLibrary.removeBook(ID);
        // display message indicating book was removed
        JOptionPane
                .showMessageDialog(
                        null,
                        "The following library book was removed:\n"
                                + lb.toString());
    } catch (Exception e1) {
        JOptionPane.showMessageDialog(null, e1.getMessage());

    }
}

}

Answer 1

更好的方法是转向CardLayout。但是如果您想坚持自己的方法，请尝试在行后添加

if (c != null) {
            contentPane.remove(c);
        }
        c = new AddBookInterface(theLibrary);
        contentPane.add(c);
        contentPane.revalidate();
        contentPane.repaint(); 
        frame.validate();
        frame.repaint();
        break;

否则您可能忘记了为事件调度程序线程安排作业。一个示例程序可以帮助您实现目标：

import java.awt.event.*;
import javax.swing.*;

public class TwoPanelTest implements ActionListener
{
    private JFrame frame;

    private JPanel panel1;
    private JPanel panel2;

    private JButton button1;
    private JButton button2;

    private JLabel label1;
    private JLabel label2;

    private JTextField tfield1;
    private JTextField tfield2;

    public TwoPanelTest()
    {
        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        panel1 = new JPanel();
        panel2 = new JPanel();

        label1 = new JLabel("This is Label 1");
        label2 = new JLabel("This is Label 2");

        button1 = new JButton("BUTTON 1");
        button2 = new JButton("BUTTON 2");
        button1.addActionListener(this);
        button2.addActionListener(this);

        tfield1 = new JTextField(20);
        tfield2 = new JTextField(20);

        panel1.add(label1);
        panel1.add(button1);
        panel1.add(tfield1);

        panel2.add(label2);
        panel2.add(button2);
        panel2.add(tfield2);

        tfield1.setText("MY TEXT WILL CHANGE.");
        frame.setContentPane(panel1);
        frame.pack();
        frame.setVisible(true);
    }

    public void actionPerformed(ActionEvent ae)
    {
        JButton button = (JButton)ae.getSource();
        if (button == button1)
        {
            frame.remove(panel1);
            frame.setContentPane(panel2);
            tfield2.setText("TEXTFIELD 2");
            frame.validate();
            frame.repaint();
        }
        else if (button == button2)
        {
            frame.remove(panel2);
            frame.setContentPane(panel1);
            tfield1.setText("TEXTFIELD 1");
            frame.validate();
            frame.repaint();
        }
    }


    public static void main(String[] args)
    {
                // Here Event Dispatcher thread is responsible for 
                // calling the function which creates and displays your GUI
                // or it itself contains the code for creating and displaying
                // the GUI, to remove hickups experienced while updating the 
                // GUI on the run.
        SwingUtilities.invokeLater(new Runnable()
            {
                public void run()
                {
                    new TwoPanelTest();
                }
            });
    }
}

希望这会有所帮助。

问候。