Java BoxLayout无法正确对齐自定义的JButton

Question

我正在使用Java swing创建游戏，并且在使用BoxLayout的“ Game Over”屏幕的设计中出现了问题。

因此，我已将两个JLabel与简单消息垂直对齐，并且尝试在下面添加另一个“再次播放” JButton。 （在JFrame级别的顶部，我正在使用BorderLayout。）

我使用加载的ImageIcon（大于默认尺寸）自定义了JButton，但屏幕显示为以下屏幕截图：

我的实现有什么问题？如下：

    //initialize the game over screen
    JPanel overPanel = new GameOverScreen();
    overPanel.setLayout(new BoxLayout(overPanel, BoxLayout.Y_AXIS));
    JLabel message = new JLabel("Game Over!");
    JLabel finalScore = new JLabel("Score: " + game.getScore());

    //Play again button
    JButton again = new JButton(new ImageIcon("files/again.jpg"));
    again.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            newGame();
        }
    });

    again.setPreferredSize(new Dimension(450, 100));
    again.setMargin(new Insets(0, 0, 0, 0));
    again.setBorder(null);

    //manage center alignments and add to JPanel
    message.setAlignmentX(Component.CENTER_ALIGNMENT);
    finalScore.setAlignmentX(Component.CENTER_ALIGNMENT);

    overPanel.add(Box.createVerticalStrut(250)); //invisible spacers
    overPanel.add(message);
    overPanel.add(finalScore);
    overPanel.add(Box.createVerticalStrut(50));
    overPanel.add(again);

    add(overPanel, BorderLayout.CENTER); //this is in a JFrame extended class