我正在上一堂基本的Pong游戏。我正在工作Pong，并且在启动时有GUI显示，很遗憾，我似乎无法从JButton开头开始游戏。我已在代码中指出问题所在，并删除了不相关的代码。

 frame.add(GUIPanel);
        JButton startButton = new JButton("Start!");     
        GUIPanel.add(startButton, BorderLayout.CENTER);
        startButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
         { 
             frame.getContentPane().remove(GUIPanel);
             frame.validate();
             frame.repaint();

             drawPanel = new DrawPanel();
             drawPanel.requestFocus();
             frame.getContentPane().add(BorderLayout.CENTER, drawPanel);
              //This is the part that freezes it, everything else works fine
              //except that the playGame method isn't called. If I remove the whole
              //startButton and whatnot I can call playGame and it works perfectly.                                                                                    
              playGame();          
           }
         }); 
         }

有任何想法吗？