CardLayout语法// .add()

Question

下面是我从CardLayoutDemo获取的代码片段。

final static String BUTTONPANEL = "Card with JButtons";
final static String TEXTPANEL = "Card with JTextField";

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//Create the panel that contains the "cards".
  cards = new JPanel(new CardLayout());
  cards.add(card1, BUTTONPANEL);
  cards.add(card2, TEXTPANEL);

我不明白上面两个字符串的用法。我假设它们是特定卡的指示符，但是为什么我们不使用下面的代码呢？

//Create the panel that contains the "cards".
      cards = new JPanel(new CardLayout());
      cards.add(buttonPanel);
      cards.add(textPanel);

我的意思是，这两个字符串没有任何实际用途，这在我看来很奇怪。

对不起，如果问题含糊不清，请原谅我。

Answer 1

String "name“是一个标识符，它允许您指示CardLayout应该显示哪个视图，下面是您在如何使用CardLayout中发布的代码片段.

//Method came from the ItemListener class implementation,
//contains functionality to process the combo box item selecting
public void itemStateChanged(ItemEvent evt) {
    CardLayout cl = (CardLayout)(cards.getLayout());
    cl.show(cards, (String)evt.getItem());
}