Experienced PLSQL, Newbie to Java -- Why would one use java?

[J. W.]

OK, so java in Oracle has been around for a while, but in my jobs,
there hasn't been a need for us to use java. So now I'm looking into
java for the apps. In the past, web apps based on Oracle technology
used PL/SQL and the web toolkit. Now, that still exists, and there's
even PL/SQL Server Pages that can be used to retrieve information and
present it to a web browser.

But, when/why would I use java in any of these apps if I'm staying on
a Oracle9i database and Oracle 9iAS app server?

thanks.