求CardLayout的例程？

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.ButtonGroup;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;public class CardLayoutDemo implements ActionListener {
    JPanel cards; //a panel that uses CardLayout
    final static String[] strings =
        {"Component 1",
         "Component 2 is so long-winded it makes the container wide",
         "Component 3"};    private static JComponent createComponent(String s) {
        JLabel l = new JLabel(s);
        l.setBorder(BorderFactory.createMatteBorder(5,5,5,5,
                                                    Color.DARK_GRAY));
        l.setHorizontalAlignment(JLabel.CENTER);
        return l;
    }    public void addCardsToPane(Container pane) {
        JRadioButton[] rb = new JRadioButton[strings.length];
        ButtonGroup group = new ButtonGroup();
        JPanel buttons = new JPanel();
        buttons.setLayout(new BoxLayout(buttons,
                                        BoxLayout.PAGE_AXIS));

        for (int i= 0; i < strings.length; i++) {
            rb[i] = new JRadioButton("Show component #" + (i+1));
            rb[i].setActionCommand(String.valueOf(i));
            rb[i].addActionListener(this);
            group.add(rb[i]);
            buttons.add(rb[i]);
        }
        rb[0].setSelected(true);

        //Create the panel that contains the "cards".
        cards = new JPanel(new CardLayout());
        for (int i = 0; i < strings.length; i++) {
            cards.add(createComponent(strings[i]), String.valueOf(i));
        }        pane.add(buttons, BorderLayout.NORTH);
        pane.add(cards, BorderLayout.CENTER);
    }    public void actionPerformed(ActionEvent evt) {
        CardLayout cl = (CardLayout)(cards.getLayout());
        cl.show(cards, (String)evt.getActionCommand());
    }    public static void main(String[] args) {
        JFrame.setDefaultLookAndFeelDecorated(true);        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        CardLayoutDemo demo = new CardLayoutDemo();
        demo.addCardsToPane(frame.getContentPane());        frame.pack();
        frame.setVisible(true);
    }
}CardLayout 对象是容器的布局管理器。它将容器中的每个组件看作一张卡片。一次只能看到一张卡片，而容器充当卡片的堆栈。当容器第一次显示时，第一个添加到 CardLayout 对象的组件为可见组件。卡片的顺序由组件对象本身在容器内部的顺序决定。CardLayout 定义了一组方法，这些方法允许应用程序按顺序地浏览这些卡片，或者显示指定的卡片。addLayoutComponent(java.awt.Component, java.lang.Object) 方法可用于将一个字符串标识符与给定卡片相关联，以便进行快速随机访问。
上面的例子中
for (int i = 0; i < strings.length; i++) {
cards.add(createComponent(strings[i]), String.valueOf(i));
}
通过定义的那个string数组来产生相应数量的component（在本例中是label），并且将这些component添加到cards这个面板中（这个面板的布局管理器就是CardLayout）。点击那几个RadioButton，在
    public void actionPerformed(ActionEvent evt) {
        CardLayout cl = (CardLayout)(cards.getLayout());
        cl.show(cards, (String)evt.getActionCommand());
    }
中根据触发事件的RadioButton对象得到ActionCommand，然后根据这个ActionCommand串，来判断显示哪个component。

调试易

求CardLayout的例程？

解决方案 »