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Chapter 16. Applets
An applet, as the name implies, is a kind of mini-application,
designed to be run by a web browser or in the context of some other
"applet viewer." Java 1.0 was
released in the early days of the World Wide Web, and it was applets
that drove the adoption of the language. In those days (late 1995 and
early 1996) web browsers could not display animated GIFs, much less
Flash animations, and client-side scripting languages like JavaScript
did not exist yet. At that time, the ability to embed a Java applet
on a web page opened up a world of interactive web content that was
not possible in any other way. Browser vendors responded by bundling
Java with their browsers. Java programming became wildly popular, and
programmers put silly animations on their web pages. In the first
edition of this book, this chapter on applets was right up front as
Chapter 3.Times have changed. Applets no longer rule the Web. Dynamic web
content is usually provided by Flash animations and JavaScript-driven
DHTML (see my book JavaScript: The Definitive
Guide for details). Applets have found a niche in large
high-end applications, such as delivering streaming stock quotes, and
for providing scientific or mathematical visualizations in online
course notes, but they are no longer commonplace. The Java platform
has grown too big to bundle with web browsers, and Java support is
now relegated to plug-in status. And this chapter has been banished
to its relatively obscure present location.This chapter demonstrates the techniques of applet writing. It
proceeds from a trivial "Hello
World" applet to more sophisticated applets. Along
the way, it explains how to:
- Draw graphics in your applet
- Handle and respond to simple user input
- Read and use values of applet parameters, allowing customization of
an applet - Load and display images and load and play sounds
