The Java API has grown by leaps and bounds since its first public
release in 1995. It is now considered sufficiently functional for
writing robust applications, but the areas to which it is being
applied continue to grow. There are many specialized APIs that may
require more resources than you have on a given Java platform. Many
of the new APIs from Sun are in the form of standard
extensions and have package names beginning in
javax.
to indicate that. Classes in packages named
java.
or javax.
are treated as
built-in classes by a web browser for purposes of applet security,
for example. Each extension is distributed in the form of a JAR file
(see Section 23.4).
If you have Java 1.1 or some clone, you will need to add each such JAR file to your CLASSPATH, as in Section 2.6.
In Java 2,
as you accumulate these and other optional APIs contained in JAR
files, you can simply drop these JAR files into the
Java Extensions Mechanism directory,
typically something like jdk1.2jrelibext
.,
instead of listing each JAR file in your CLASSPATH variable and
watching CLASSPATH grow and grow and grow. Effective with Java 2, the
runtime looks here for any and all JAR and zip files, so no special
action is needed. In fact, unlike many other system changes, you do
not even need to reboot your computer, since this directory is
scanned each time the JVM starts up. You may, however, need to
restart a long-running program such as an IDE for it to notice the
change. Try it and see first.
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