Learning Java

CardLayout

CardLayout is a special layout manager for creating the effect of a stack of cards. Instead of arranging all of the container’s components, it displays only one at a time. You might use this kind of layout to implement a hypercard stack or a Windows-style set of configuration screens. If CardLayout sounds interesting, you might also want to investigate the JTabbedPane component, described in Chapter 14.

To add a component to a CardLayout, use a two-argument version of the container’s add( ) method; the extra argument is an arbitrary string that serves as the card’s name:

add("netconfigscreen", myComponent);

To bring a particular card to the top of the stack, call the CardLayout’s show( ) method with two arguments: the parent Container and the name of the card you want to show. There are also methods like first( ) , last( ), next( ), and previous( ) for working with the stack of cards. These are all CardLayout instance methods. To invoke them, you need a reference to the CardLayout object itself, not to the container it manages. Each method takes a single argument: the parent Container. Here’s a simple example:

//file: Card.java import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Card extends JPanel { CardLayout cards = new CardLayout( ); public Card( ) { setLayout(cards); ActionListener listener = new ActionListener( ) { public void actionPerformed(ActionEvent e) { cards.next(Card.this); } }; JButton button; button = new JButton("one"); button.addActionListener(listener); ...