Exceptions - Java Software Solutions: Foundations of Program Design - page 570

part of the component. Scroll bars are useful when space within a GUI is limited
or when the component being viewed is large or can change in size dynamically.
The program in Listing 11.13 presents a frame that con-
tains a single scroll pane. The scroll pane is used to view
an image of a fairly large subway map for Philadelphia and
the surrounding areas. The image is put into a label, and
the label is added to the scroll pane using the JScrollPane
constructor.

KEY CONCEPT
A scroll pane is useful for viewing
large objects or large amounts of
data.

LISTING 11.13

//********************************************************************
// TransitMap.java Author: Lewis/Loftus
//
// Demonstrates the use of a scroll pane.
//********************************************************************

import java.awt.*;
import javax.swing.*;

public class TransitMap
{
//-----------------------------------------------------------------
// Presents a frame containing a scroll pane used to view a large
// map of the Philadelphia subway system.
//-----------------------------------------------------------------
public static void main (String[] args)
{
// SEPTA = SouthEast Pennsylvania Transit Authority
JFrame frame = new JFrame ("SEPTA Transit Map");

frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

ImageIcon image = new ImageIcon ("septa.jpg");
JLabel imageLabel = new JLabel (image);

JScrollPane sp = new JScrollPane (imageLabel);
sp.setPreferredSize ( new Dimension (450, 400));
frame.getContentPane().add (sp);
frame.pack();
frame.setVisible( true );
}
}