java - CardLayout 对齐不正确

Question

我是java初学者。在第二个卡片面板中，用户名和密码对齐不正确。有什么办法可以解决吗？我还想知道使用多个框架的缺点是什么。

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

    public class CardLayoutTest extends JFrame {

        private static final long serialVersionUID = 1L;
        private JPanel cardPanel, jp1, jp2, buttonPanel;
        private JLabel jl1, jl2;
        private JTextField jt1;
        private JPasswordField jt2;
        private JButton btn1, btn2;
        private CardLayout cardLayout = new CardLayout();

        public CardLayoutTest() {
            setTitle("Login");
            setSize(400, 300);
            cardPanel = new JPanel();
            buttonPanel = new JPanel();
            cardPanel.setLayout(cardLayout);
            jp1 = new JPanel();
            jp2 = new JPanel();
            jt1=new JTextField();
            jt2=new JPasswordField();
            jl1 = new JLabel("Username");
            jl2 = new JLabel("Password");
            //jp1.add(jl1);
            jp2.add(jl1);
            jp2.add(jt2);
            jp2.add(jl2);
            jp2.add(jt2);
            cardPanel.add(jp1, "1");
            cardPanel.add(jp2, "2");
            btn2 = new JButton("Show Card 2");
            btn2.addActionListener(new ActionListener() {

                public void actionPerformed(ActionEvent e) {
                    cardLayout.show(cardPanel, "2");
                }
            });
            buttonPanel.add(btn2);
            add(cardPanel, BorderLayout.CENTER);
            add(buttonPanel, BorderLayout.SOUTH);
        }

        public static void main(String[] args) {
            EventQueue.invokeLater(new Runnable() {

                @Override
                public void run() {
                    CardLayoutTest frame = new CardLayoutTest();
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.setVisible(true);
                }
            });
        }
    }

Answer 1

In second cardpanel the username and password alignment is not coming properly.

默认情况下，JPanel 使用 FlowLayout，因此组件显示在一行上。

Is there any way to fix it?

使用适当的布局管理器(或布局管理器的组合)来获得所需的对齐方式。

阅读 Swing 教程中关于 Layout Managers 的部分了解更多信息和示例。