Java.布局管理器.CardLayout-GridLayout

//TestCardLayout.java

package myprojects.testcardlayout;

import java.awt.*;
import java.awt.event.*;

class TestCardLayout extends Frame {
CardLayout cl=new CardLayout();
Panel plCenter=new Panel();
public TestCardLayout() {

Panel plWest=new Panel();
plWest.setLayout(new GridLayout(3,1));
Button btnPrev=new Button("Prev");
Button btnNext=new Button("Next");
Button btnThree=new Button("Three");
plWest.add(btnPrev);
plWest.add(btnNext);
plWest.add(btnThree);
add(plWest,"West");

plCenter.setLayout(cl);
plCenter.add(new Button("one"),"1");
plCenter.add(new Button("two"),"2");
plCenter.add(new Button("three"),"3");
plCenter.add(new Button("four"),"4");
plCenter.add(new Button("five"),"5");
add(plCenter);

class MyActionListener implements ActionListener{
public void actionPerformed(ActionEvent e){
if(e.getActionCommand().equals("Prev")){
cl.previous(plCenter);
}
else if(e.getActionCommand().equals("Next")){
cl.next(plCenter);
}
else{
cl.show(plCenter,"3");
}
}
}

MyActionListener ma=new MyActionListener();
btnPrev.addActionListener(ma);
btnNext.addActionListener(ma);
btnThree.addActionListener(ma);

addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
dispose();
System.exit(0);
}
});
}

public static void main(String args[]) {
System.out.println("Starting TestCardLayout...");
TestCardLayout mainFrame = new TestCardLayout();
mainFrame.setSize(400, 400);
mainFrame.setTitle("TestCardLayout");
mainFrame.setVisible(true);
}
}