JButton不在JFrame的JPanel上显示

Question

Im trying to display 9 3x3 grids in a 3x3 grid. None of the buttons are showing up though. I had to create all the individual buttons and i didnt know if they took up to much space of if there is an obvious error in my code. Thanks for any input!

 public class BoardGui extends JFrame{
    private JPanel center;
    private JPanel grid00;
    private JPanel grid01;
    private JPanel grid02;
    private JPanel grid10;
    private JPanel grid11;
    private JPanel grid12;
    private JPanel grid20;
    private JPanel grid21;
    private JPanel grid22;



    private JButton sq0000,sq0100,sq0200,sq1000,sq1100,
        sq1200,sq2000,sq2100,sq2200;
        private JButton sq0001,sq0101,sq0201,sq1001,sq1101,sq1201,sq2001
        ,sq2101,sq2201;
        private JButton sq0002,sq0102,sq0202,sq1002,sq1102,sq1202
        ,sq2002,sq2102,sq2202;
        private JButton sq0010,sq0110,sq0210,sq1010,sq1110,sq1210,
        sq2010,sq2110,sq2210;
        private JButton sq0011,sq0111,sq0211,sq1011,sq1111,
        sq1211,sq2011,sq2111,sq2211;
        private JButton sq0012,sq0112,sq0212,sq1012,sq1112,sq1212,
        sq2012,sq2112,sq2212;
        private JButton sq0020,sq0120,sq0220,sq1020,sq1120,sq1220,
        sq2020,sq2120,sq2220;
        private JButton sq0021,sq0121,sq0221,sq1021,sq1121,
        sq1221,sq2021,sq2121,sq2221;
        private JButton sq0022,sq0122,sq0222,sq1022,sq1122,sq1222,
        sq2022,sq2122,sq2222;

        public void Board(){

            setLayout(new BorderLayout());

            center.setLayout(new GridLayout(3,3));

            grid00 = new JPanel();
            grid01 = new JPanel();
            grid02 = new JPanel();
            grid10 = new JPanel();
            grid11 = new JPanel();
            grid12 = new JPanel();
            grid20 = new JPanel();
            grid21 = new JPanel();
            grid22 = new JPanel();

            grid00.setLayout(new GridLayout(3,3));
            grid01.setLayout(new GridLayout(3,3));
            grid02.setLayout(new GridLayout(3,3));
            grid10.setLayout(new GridLayout(3,3));
            grid11.setLayout(new GridLayout(3,3));
            grid12.setLayout(new GridLayout(3,3));
            grid20.setLayout(new GridLayout(3,3));
            grid21.setLayout(new GridLayout(3,3));
            grid22.setLayout(new GridLayout(3,3));

            sq0000 = new JButton();
            sq0001 = new JButton();
            sq0002 = new JButton();
            sq0010 = new JButton();
            sq0011 = new JButton();
            sq0012 = new JButton();
            sq0020 = new JButton();
            sq0021 = new JButton();
            sq0022 = new JButton();

            sq0100 = new JButton();
            sq0101 = new JButton();
            sq0102 = new JButton();
            sq0110 = new JButton();
            sq0111 = new JButton();
            sq0112 = new JButton();
            sq0120 = new JButton();
            sq0121 = new JButton();
            sq0122 = new JButton();

            sq0200 = new JButton();
            sq0201 = new JButton();
            sq0202 = new JButton();
            sq0210 = new JButton();
            sq0211 = new JButton();
            sq0212 = new JButton();
            sq0220 = new JButton();
            sq0221 = new JButton();
            sq0222 = new JButton();

            sq1000 = new JButton();
            sq1001 = new JButton();
            sq1002 = new JButton();
            sq1010 = new JButton();
            sq1011 = new JButton();
            sq1012 = new JButton();
            sq1020 = new JButton();
            sq1021 = new JButton();
            sq1022 = new JButton();

            sq1100 = new JButton();
            sq1101 = new JButton();
            sq1102 = new JButton();
            sq1110 = new JButton();
            sq1111 = new JButton();
            sq1112 = new JButton();
            sq1120 = new JButton();
            sq1121 = new JButton();
            sq1122 = new JButton();

            sq1200 = new JButton();
            sq1201 = new JButton();
            sq1202 = new JButton();
            sq1210 = new JButton();
            sq1211 = new JButton();
            sq1212 = new JButton();
            sq1220 = new JButton();
            sq1221 = new JButton();
            sq1222 = new JButton();

            sq2000 = new JButton();
            sq2001 = new JButton();
            sq2002 = new JButton();
            sq2010 = new JButton();
            sq2011 = new JButton();
            sq2012 = new JButton();
            sq2020 = new JButton();
            sq2021 = new JButton();
            sq2022 = new JButton();

            sq2100 = new JButton();
            sq2101 = new JButton();
            sq2102 = new JButton();
            sq2110 = new JButton();
            sq2111 = new JButton();
            sq2112 = new JButton();
            sq2120 = new JButton();
            sq2121 = new JButton();
            sq2122 = new JButton();

            sq2200 = new JButton();
            sq2201 = new JButton();
            sq2202 = new JButton();
            sq2210 = new JButton();
            sq2211 = new JButton();
            sq2212 = new JButton();
            sq2220 = new JButton();
            sq2221 = new JButton();
            sq2222 = new JButton();

            grid00.add(sq0000);
            grid00.add(sq0001);
            grid00.add(sq0002);
            grid00.add(sq0010);
            grid00.add(sq0011);
            grid00.add(sq0012);
            grid00.add(sq0020);
            grid00.add(sq0021);
            grid00.add(sq0022);

            grid01.add(sq0100);
            grid01.add(sq0101);
            grid01.add(sq0102);
            grid01.add(sq0110);
            grid01.add(sq0111);
            grid01.add(sq0112);
            grid01.add(sq0120);
            grid01.add(sq0121);
            grid01.add(sq0122);

            grid02.add(sq0200);
            grid02.add(sq0201);
            grid02.add(sq0202);
            grid02.add(sq0210);
            grid02.add(sq0211);
            grid02.add(sq0212);
            grid02.add(sq0220);
            grid02.add(sq0221);
            grid02.add(sq0222);

            grid10.add(sq1000);
            grid10.add(sq1001);
            grid10.add(sq1002);
            grid10.add(sq1010);
            grid10.add(sq1011);
            grid10.add(sq1012);
            grid10.add(sq1020);
            grid10.add(sq1021);
            grid10.add(sq1022);

            grid11.add(sq1100);
            grid11.add(sq1101);
            grid11.add(sq1102);
            grid11.add(sq1110);
            grid11.add(sq1111);
            grid11.add(sq1112);
            grid11.add(sq1120);
            grid11.add(sq1121);
            grid11.add(sq1122);

            grid12.add(sq1200);
            grid12.add(sq1201);
            grid12.add(sq1202);
            grid12.add(sq1210);
            grid12.add(sq1211);
            grid12.add(sq1212);
            grid12.add(sq1220);
            grid12.add(sq1221);
            grid12.add(sq1222);

            grid20.add(sq2000);
            grid20.add(sq2001);
            grid20.add(sq2002);
            grid20.add(sq2010);
            grid20.add(sq2011);
            grid20.add(sq2012);
            grid20.add(sq2020);
            grid20.add(sq2021);
            grid20.add(sq2022);

            grid21.add(sq2100);
            grid21.add(sq2101);
            grid21.add(sq2102);
            grid21.add(sq2110);
            grid21.add(sq2111);
            grid21.add(sq2112);
            grid21.add(sq2120);
            grid21.add(sq2121);
            grid21.add(sq2122);

            grid22.add(sq2200);
            grid22.add(sq2201);
            grid22.add(sq2202);
            grid22.add(sq2210);
            grid22.add(sq2211);
            grid22.add(sq2212);
            grid22.add(sq2220);
            grid22.add(sq2221);
            grid22.add(sq2222);

            center.add(grid00);
            center.add(grid01);
            center.add(grid02);
            center.add(grid10);
            center.add(grid11);
            center.add(grid12);
            center.add(grid20);
            center.add(grid21);
            center.add(grid22);

            add(center, BorderLayout.CENTER);

        }

        public static void main(String[] args) {
            BoardGui gui = new BoardGui();
            gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            gui.setSize(700, 700);
            gui.setResizable(true);
            gui.setVisible(true);
            gui.setTitle("Tic Tac Toe Extreme");
        }

    }

Answer 1

So far, by looking at your code, it's going to generate a NullPointerException because center is never initialized...as to if this is your actually issue, I can only guess

Having said that, you need to learn how to use arrays and break you code down into manageable chunks.

There is so much repetition, you'd be crazy not to re-use it in some way, for example...

You could create a custom JPanel whose sole responsibility it is, is to show a 3x3 grid of buttons...

public class ButtonPane extends JPanel {

    private JButton[][] btns;

    public ButtonPane() {
        setLayout(new GridLayout(3, 3));
        btns = new JButton[3][3];
        for (int row = 0; row < 3; row++) {
            for (int col = 0; col < 3; col++) {
                btns[row][col] = new JButton(row + "x" + col);
                add(btns[row][col]);
            }
        }
    }

    public JButton getButtonAt(int row, int col) {
        return btns[row][col];
    }

}

You could then create another custom panel, whose responsibility it is, is to show a 3x3 grid of these button panels...

public class ContentPane extends JPanel {

    private ButtonPane[][] buttonPanels;

    public ContentPane() {
        setLayout(new GridLayout(3, 3));
        buttonPanels = new ButtonPane[3][3];
        for (int row = 0; row < 3; row++) {
            for (int col = 0; col < 3; col++) {
                buttonPanels[row][col] = new ButtonPane();
                add(buttonPanels[row][col]);
            }
        }
    }

    public ButtonPane getButtonPaneAt(int row, int col) {
        return buttonPanels[row][col];
    }

}

And then put it all together on a frame or other container...

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test{

    public static void main(String[] args) {
        new JavaApplication834();
    }

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

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new ContentPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class ContentPane extends JPanel {

        private ButtonPane[][] buttonPanels;

        public ContentPane() {
            setLayout(new GridLayout(3, 3));
            buttonPanels = new ButtonPane[3][3];
            for (int row = 0; row < 3; row++) {
                for (int col = 0; col < 3; col++) {
                    buttonPanels[row][col] = new ButtonPane();
                    add(buttonPanels[row][col]);
                }
            }
        }

        public ButtonPane getButtonPaneAt(int row, int col) {
            return buttonPanels[row][col];
        }

    }

    public class ButtonPane extends JPanel {

        private JButton[][] btns;

        public ButtonPane() {
            setLayout(new GridLayout(3, 3));
            btns = new JButton[3][3];
            for (int row = 0; row < 3; row++) {
                for (int col = 0; col < 3; col++) {
                    btns[row][col] = new JButton(row + "x" + col);
                    add(btns[row][col]);
                }
            }
        }

        public JButton getButtonAt(int row, int col) {
            return btns[row][col];
        }

    }

}

Remember, Java is an object oriented language, one of it's goals to produce re-usable blocks...