如何使按钮耗尽BorderLayout中的所有空间而不留空白区域？

Question

我有一个程序创建一个8x8网格填充随机颜色（已经完成这一点），我应该在底部添加一个按钮，它应该填充整个底部部分，用于重置颜色。我已经有了网格和按钮，但是，我的按钮没有填满底部的整个空间，只有大约一半。如何让它填满整个空间？

我的代码：

public void createGUI() 
{
    guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    guiFrame.setTitle("Label demo");
    JPanel mainPanel = new JPanel();
    JPanel gridPanel = new JPanel();
    JPanel buttonPanel = new JPanel();
    JButton refreshButton = new JButton("Press me to refresh labels");
    mainPanel.setLayout(new BorderLayout());
    guiFrame.getContentPane().add(mainPanel);
    gridPanel.setLayout(new GridLayout(8, 8));
    for (int i = 0; i < arrayLabels.length; i++)
    {
        arrayLabels[i] = new ColorLabel(80, 80, new Color(rand.nextInt()), 0, new Color(rand.nextInt()));
    }

    for (int i = 0; i < 8*8; i++)
    {
        gridPanel.add(arrayLabels[i]);
    }
    guiFrame.getContentPane().add(gridPanel);
    buttonPanel.add(refreshButton);
    guiFrame.getContentPane().add(buttonPanel, BorderLayout.SOUTH);
    guiFrame.setVisible(true);
}

我的程序输出目前是：https://imgur.com/a/fw1Bx92

Answer 1

还设置了刷新按钮的JPanel布局！我在下面做一个例子，你可以检查一下：

public static void createGUI() 
{
    JFrame guiFrame = new JFrame("a");
    guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    guiFrame.setTitle("Label demo");
    JPanel mainPanel = new JPanel();
    JPanel gridPanel = new JPanel();
    JPanel buttonPanel = new JPanel(new BorderLayout());
    JButton refreshButton = new JButton("Press me to refresh labels");
    mainPanel.setLayout(new BorderLayout());
    guiFrame.getContentPane().add(mainPanel);
    gridPanel.setLayout(new GridLayout(8, 8));
    JLabel arrayLabels[] = new JLabel[64];
    for (int i = 0; i < 64; i++)
    {
        arrayLabels[i] = new JLabel("a");
    }

    for (int i = 0; i < 8*8; i++)
    {
        gridPanel.add(arrayLabels[i]);
    }
    guiFrame.getContentPane().setLayout(new BorderLayout());
    guiFrame.getContentPane().add(gridPanel,BorderLayout.CENTER);
    buttonPanel.add(refreshButton,BorderLayout.CENTER);
    guiFrame.getContentPane().add(buttonPanel, BorderLayout.SOUTH);
    guiFrame.setVisible(true);
}