JPanel周围的数字; JPanel边界？

Question

I am creating a mini game and I'm stuck. This grid is supposed to be nxn but in this case it's 6x6 until I figure things out.

Anyhow, I'd like to create a transparent border

which will add centered numbers above each cell (on the left side and up, however, later on I must add the rights side and down). What would be a good way to do this? I searched around because I know that chess boards have this kind of "border" and I actually searched them up, but with no luck.

This is a code snippet, the cells are contained in a simple JPanel while everything else is in the JFrame.

public GameFrame() {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (ClassNotFoundException | InstantiationException | IllegalAccessException
                    | UnsupportedLookAndFeelException ex) {
            }

            JFrame frame = new JFrame("Game");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setLayout(new BorderLayout());
            frame.add(new GamePanel());
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);

            JMenuBar menubar = new JMenuBar();
            JMenu menu1 = new JMenu ("New");
            menubar.add(menu1);
            JMenu menu2 = new JMenu ("Load");
            menubar.add(menu2);
            JMenu menu3 = new JMenu ("Save");
            menubar.add(menu3);
            JMenu menu4 = new JMenu ("Size");
            menubar.add(menu4);
            JMenu menu5 = new JMenu ("Check");
            menubar.add(menu5);
            JMenu menu6 = new JMenu ("Solve");
            menubar.add(menu6);
            frame.setJMenuBar(menubar);
        }
    });

}

public class GamePanel extends JPanel {
    public GamePanel() {
        setLayout(new GridBagLayout());

        GridBagConstraints gbc = new GridBagConstraints();
        for (int row = 0; row < 6; row++) {
            for (int col = 0; col < 6; col++) {
                gbc.gridx = col;
                gbc.gridy = row;

                CellPanel cellPanel = new CellPanel();
                Border border = null;
                if (row < 5) {
                    if (col < 5) {
                        border = new MatteBorder(1, 1, 0, 0, Color.GRAY);
                    } else {
                        border = new MatteBorder(1, 1, 0, 1, Color.GRAY);
                    }
                } else {
                    if (col < 5) {
                        border = new MatteBorder(1, 1, 1, 0, Color.GRAY);
                    } else {
                        border = new MatteBorder(1, 1, 1, 1, Color.GRAY);
                    }
                }
                cellPanel.setBorder(border);
                add(cellPanel, gbc);
            }
        }
    }
}
public class CellPanel extends JPanel {
    Color defaultBackground;

    public CellPanel() {
        addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent e) {
                defaultBackground = getBackground();

                if (getBackground().equals(Color.BLUE)) { 
                    setBackground(null);
                } else {
                    setBackground(Color.BLUE);
                }
            }

        });
    }

    public Dimension getPreferredSize() {
        return new Dimension(50, 50);
    }
}

Answer 1

Maybe try to add an extra column and row to your gridbaglayout. Then either control them as special cases in your for() construct or start your indexes at 1 and then go back and address them outside your for() construct.

Create another inherited JPanel that you can use as CellLabels, especially if they are all going to look alike.