JavaSwing 按钮背景

Question

我正在制作国际象棋游戏，并且正在使用 JavaSwing 作为 GUI。我遇到的问题是按钮的背景显示不正确。该板由 8x8 个按钮组成，我想要灰色和白色。目前按钮有背景颜色的轮廓，但按钮本身的主要部分是白色的。如何使整个按钮与背景颜色相同？

制作按钮的当前代码：（注意）图像是用另一种方法添加的。 按钮

        boardPanel = new JPanel(new GridLayout(8, 8));

        boardButtons = new JButton[8][8];
        for (int i = 0; i < 8; i++) {
            for (int j = 0; j < 8; j++) {
                boardButtons[i][j] = new JButton();
                boardButtons[i][j].setPreferredSize(new Dimension(100, 100));
                boardButtons[i][j].setMinimumSize(new Dimension(100, 100));
                boardButtons[i][j].addActionListener(buttonListener);
                if ((i + j) % 2 == 0) {
                    boardButtons[i][j].setBackground(Color.WHITE);
                } else {
                    boardButtons[i][j].setBackground(Color.GRAY);
                }
                boardButtons[i][j].setOpaque(true);
                boardPanel.add(boardButtons[i][j]);
            }
        }

        // Create a new panel and add the board panel and white space panel to it
        JPanel contentPane = new JPanel();
        contentPane.setPreferredSize(new Dimension(1200, 800)); // fixed size for board panel
        contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.X_AXIS));
        contentPane.add(boardPanel);

        JPanel whiteSpacePanel = new JPanel();
        whiteSpacePanel.setPreferredSize(new Dimension(400, 800)); // desired size of white space
        whiteSpacePanel.setBackground(Color.CYAN);
        contentPane.add(whiteSpacePanel);

        // Add the new panel to the frame and set some properties
        setContentPane(contentPane);
        setTitle("Capture The Quad Board");
        setResizable(false); // prevent resizing of the window
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setVisible(true);
        paintBoard();

当前板：