Question

java中Panel如何添加边框？？？？？？？

java中Panel如何添加边框？？？？？？
不是JPanel,

Answer 1

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
final class p extends Frame {
    final static private Dimension SIZE = new Dimension(800, 600);
    public String getTitle() {return "p";}
    public Dimension getPreferredSize() {return SIZE;}
    public Dimension getMinimumSize() {return SIZE;}
    public Dimension getMaximumSize() {return SIZE;}
    public Dimension getSize() {return SIZE;}
    private Panel panel;
    p() throws HeadlessException {
        init();
        attachListeners();
        doLay();
        setVisible(true);
    }

    private void init() {
        panel=new Panel(){
            public Dimension getPreferredSize() {
                return new Dimension(100,233);
            }

            public void paint(Graphics g) {
                super.paint(g);

                Graphics g2=g.create();
                g2.setColor(Color.RED);
                
                g2.drawLine(0,0,getWidth(), 0);
                g2.drawLine(0,getHeight()-2,getWidth()-2, getHeight()-2);
                g2.drawLine(0,0,0,getHeight());
                g2.drawLine(getWidth()-2,0,getWidth()-2,getHeight()-2);
                g2.dispose();
            }
        };
        panel.setBounds(44,44,111,222);
    }

    private void attachListeners() {
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(1);
            }
        });
    }

    private void doLay() {
        setLayout(null);
        add(panel);
        pack();
    }

    public static void main(String... args) {
        System.setProperty("swing.defaultlaf", "com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
        SwingUtilities.invokeLater(p::new);
    }
}