6.布局：CardLayout（卡片布局）

• 选项卡 ```java public static void main(String[] args) {

    Frame f = new Frame("CardLayout");
    f.setSize(400, 600);
    f.setVisible(true);
    //创建2个Panel容器，一个存放按钮,一个存放卡片
    Panel p1 = new Panel();
    Panel p2 = new Panel();
    //创建5个按钮，并将其添加到p1中
    Button b1 = new Button("number 1");
    Button b2 = new Button("number 2");
    Button b3 = new Button("number 3");
    Button b4 = new Button("number 4");
    Button b5 = new Button("number 5");
    p1.add(b1);
    p1.add(b2);
    p1.add(b3);
    p1.add(b4);
    p1.add(b5);

    //将p2设置为CardLayout，并添加5个组件，每个组件都相当于一个卡片
    CardLayout cardLayout = new CardLayout();
    p2.setLayout(cardLayout);
    p2.add("number 1",new Button("number 1"));
    p2.add("number 2",new Button("number 2"));
    p2.add("number 3",new Button("number 3"));
    p2.add("number 4",new Button("number 4"));
    p2.add("number 5",new Button("number 5"));
    //将p1中的5个按钮，分别添加监听事件，当用户单击时，显示指定的卡片
    ActionListener listener = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            String command = e.getActionCommand();
            cardLayout.show(p2,command);
        }
    };
    b1.addActionListener(listener);
    b2.addActionListener(listener);
    b3.addActionListener(listener);
    b4.addActionListener(listener);
    b5.addActionListener(listener);
    //将两个Panel容器添加到Frame中
    f.add(p1,BorderLayout.NORTH);
    f.add(p2);
}

```