CardLayout.show的显示问题（JAVA ）

出错信息:
Exception in thread "main" java.lang.IllegalArgumentException: wrong parent for CardLayout
at java.awt.CardLayout.checkLayout(CardLayout.java:383)
at java.awt.CardLayout.show(CardLayout.java:505)
at htmlbrowser.CenterPanel.main(CenterPanel.java:14)

//例如你的窗口对象是：fom  

                                 JFrame fom = new JFrame("helloworld");

                                  CardLayout card = new CardLayout(50,10);

                                 如果直接使用这样的方法show就会出现上面的错误：card.show(fom,"xxx");//XXX代表字符串

                                  应该改为：card.show(fom.getContentPane(), "xxx");

                                   因为java布局管理器要放在窗口的内容窗格显示。