Java The Complete Reference, Seventh Edition

Handling Action Events

Each ofDownloadManager’s GUI controls registers anActionListenerthat invokes its

respective action method.ActionListeners are triggered each time an action event takes

place on a GUI control. For example, when a button is clicked, anActionEventis generated

and each of the button’s registeredActionListeners is notified. You may have noticed

a similarity between the wayActionListeners work and the Observer pattern discussed

earlier. That is because they are the same pattern with two different naming schemes.

Compiling and Running the Download Manager

CompileDownloadManagerlike this:

javac DownloadManager.java DownloadsTableModel.java ProgressRenderer.java Download.java

RunDownloadManagerlike this:

javaw DownloadManager

The Download Manager is easy to use. First, enter the URL of a file that you want to

download in the text field at the top of the screen. For example, to download a file called

0072229713_code.zip from the McGraw-Hill web site enter

http://books.mcgraw-hill.com/downloads/products/0072229713/0072229713_code.zip

This is the file that contains the code for my bookThe Art of Java, which I co-authored with

James Holmes.

After adding a download to the Download Manager, you can manage it by selecting it

in the table. Once selected, you can pause, cancel, resume, and clear a download. Figure 33-2

shows the Download Manager in action.

Chapter 33: Creating a Download Manager in Java 989

FIGURE 33-2 The Download Manager in action