Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

652 Chapter 17 GUI Components
JList inside
a scroll
pane
JPanel with
GridLayout
An image is
displayed on a
Jlabel
FIGURE 17.9
When the countries in the list are selected, corresponding images of their flags are displayed in the labels.
Here are the major steps in the program:
1. Create the user interface.
Create a list with nine country names as selection values, and place the list inside a
scroll pane. Place the scroll pane in the west of the frame. Create nine labels to be used
to display the countries’ flag images. Place the labels in the panel, and place the panel
in the center of the frame.
2. Process the event.
Create a listener to implement the valueChanged method in the
ListSelectionListener interface to set the selected countries’ flag images in the
labels.
LISTING 17.5
ListDemo.java
1 import java.awt.*;
2 import javax.swing.*;
3 import javax.swing.event.*;
4
5 public class ListDemo extends JFrame {
6 final int NUMBER_OF_FLAGS = 9;
7
8 // Declare an array of Strings for flag titles
9 private String[] flagTitles = {"Canada", "China", "Denmark",
10 "France", "Germany", "India", "Norway", "United Kingdom",
11 "United States of America"};
12
13 // The list for selecting countries
14 private JList jlst = new JList(flagTitles);
15
16 // Declare an ImageIcon array for the national flags of 9 countries
17 private ImageIcon[] imageIcons = {
18 new ImageIcon("image/ca.gif"),
19 new ImageIcon("image/china.gif"),
20 new ImageIcon("image/denmark.gif"),
21 new ImageIcon("image/fr.gif"),
22 new ImageIcon("image/germany.gif"),
23 new ImageIcon("image/india.gif"),
24 new ImageIcon("image/norway.gif"),
25 new ImageIcon("image/uk.gif"),
26 new ImageIcon("image/us.gif")
27 };
28