JPanel setLayout GridLayout无效

Question

我想为从JPanel扩展的Cell设置布局，但它在ObjectListener类中的public void actionPerformed（ActionEvent e）中不起作用 任何人都可以帮忙吗？ 这是我的代码：

public class Cell extends JPanel
{
    ArrayList<GameObject> objects = new ArrayList<GameObject>();

    Cell()
    {
        setBackground(Color.orange);
        setLayout(new GridLayout(2, 2));
        GameObject gameObject = new GameObject();
        objects.add(gameObject);
        add(gameObject);
        gameObject.addActionListener(new ObjectListener(this));
    }
}
public class ObjectListener implements ActionListener
{
    Cell cell;

    ObjectListener(Cell cell)
    {
        this.cell = cell;
    }

    public void actionPerformed(ActionEvent e)
    {
        cell.removeAll();
        GridLayout gridLayout = new GridLayout(2, 2, 3, 3);
        cell.setLayout(gridLayout);
        GameObject x = new GameObject();
        cell.add(x);
        GameObject y = new GameObject();
        cell.add(y);
        cell.repaint();
        /* the gridlayout is not working here */
    }
}
public class GameObject extends JButton
{
    GameObject()
    {
        setVisible(true);
        setContentAreaFilled(false);
        setSize(10, 10);
    }
}