Question

我必须设置一个基本的JAVA应用程序，包括基于swing的GUI。我的想法是创建一个JFrame和不同的JPanels，并根据用户输入来更改显示的JPanel。运行我的应用程序后，显示JFrame但不显示JPanel的内容。我在这里想到它应该向前迈进......但似乎并非如此。希望你能给我一个提示：）

这是我的主要内容：

public class Client {
    public static void main(String[] args) {
        MainWindow window = new MainWindow();
        window.setVisible(true);

        LoginView pane = new LoginView();
        window.getContentPane().add(pane);

        window.invalidate();
        window.repaint();
    }
}

我的MainWindow：

package client;

public class MainWindow extends javax.swing.JFrame {
    public MainWindow() {
        initComponents();
    }
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    private void initComponents() {
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 352, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(0, 250, Short.MAX_VALUE)
        );
        pack();
    }
}

我的LoginView：

package client.views;

public class LoginView extends javax.swing.JPanel {
    public LoginView() {
        initComponents();
    }
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    private void initComponents() {
        jLabel1 = new javax.swing.JLabel();
        jLabel1.setText("Login");
        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .addContainerGap()
                .add(jLabel1)
                .addContainerGap(345, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .addContainerGap()
                .add(jLabel1)
                .addContainerGap(264, Short.MAX_VALUE))
        );
    }
    private javax.swing.JLabel jLabel1;
}

Answer 1

除了调用revalidate()和repaint()之外，我知道的另一件事是，而不是只调用add()到当前内容窗格，只需设置一个新内容。

我认为您的问题与向当前内容窗格添加组件的方式不正确有关。我认为这就是这种情况，因此，请使用setContentPane()方法。

Answer 2

作为替代方案，请使用CardLayout更改面板。

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Client {

    public static void main(String[] args) {
        JFrame window = new JFrame();
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final CardLayout cl = new CardLayout();
        final JPanel cards = new JPanel(cl);
        cards.add(new LoginView(), "Login");
        cards.add(new MainView(), "Main");
        window.add(cards);
        JPanel control = new JPanel();
        control.add(new JButton(new AbstractAction("Login") {

            @Override
            public void actionPerformed(ActionEvent e) {
                cl.show(cards, "Main");
            }
        }));
        window.add(control, BorderLayout.SOUTH);
        window.pack();
        window.setLocationRelativeTo(null);
        window.setVisible(true);
    }
}

class MainView extends javax.swing.JPanel {

    public MainView() {
        initComponents();
    }
    ...
}

class LoginView extends javax.swing.JPanel {

    public LoginView() {
        initComponents();
    }
    ...
}

将其添加到JFrame后，JPanel不会显示

2 个答案: