GUI Components: Part 2 - Java: How to Program Early Objects - page 933

22.7 JDesktopPane and JInternalFrame
A multiple-document interface ( MDI ) is a main window (called the parent window ) con-
taining other windows (called child windows ) and is often used to manage several open doc-
uments. For example, many e-mail programs allow you to have several windows open at the
same time, so you can compose or read multiple e-mail messages simultaneously. Similarly,
many word processors allow the user to open multiple documents in separate windows with-
in a main window, making it possible to switch between them without having to close one
to open another. The application in Figs. 22.11-22.12 demonstrates Swing's JDesktopPane
and JInternalFrame classes for implementing multiple-document interfaces.

1

// Fig. 22.11: DesktopFrame.java

2

// Demonstrating JDesktopPane.

3

import java.awt.BorderLayout;

4

import java.awt.Dimension;

5

import java.awt.Graphics;

6

import java.awt.event.ActionListener;

7

import java.awt.event.ActionEvent;

8

import java.util.Random;

9

import javax.swing.JFrame;

10
11

import javax.swing.JDesktopPane;

import javax.swing.JMenuBar;

12 import javax.swing.JMenu;

13 import javax.swing.JMenuItem;

14
15

import javax.swing.JInternalFrame;

import javax.swing.JPanel;

16 import javax.swing.ImageIcon;

17
18 public class DesktopFrame extends JFrame

19 {

20 private final JDesktopPane theDesktop;

21
22 // set up GUI

23 public DesktopFrame()

24 {

25 super ( "Using a JDesktopPane" );

26
27 JMenuBar bar = new JMenuBar();

28 JMenu addMenu = new JMenu( "Add" );

29 JMenuItem newFrame = new JMenuItem( "Internal Frame" );

30
31 addMenu.add(newFrame); // add new frame item to Add menu

32 bar.add(addMenu); // add Add menu to menu bar

33 setJMenuBar(bar); // set menu bar for this application

34
35 theDesktop = new JDesktopPane();

add(theDesktop); // add desktop pane to frame 36

37

38 // set up listener for newFrame menu item

39 newFrame.addActionListener(

Fig. 22.11 | Multiple-document interface. (Part 1 of 2.)