Why the Java Runaround?

[Andavane]

I'm trying to seize the bull by the horns by understanding something about this Java Devil; I think I should remove the one here is Oneiric and update it.
But first I am opening Terminal and typing "which java" which returns:

/usr/bin/java

and when I go and look at that file, it's a link to:

/etc/alternatives/java

and when I go there I see THAT is a link to:

/usr/lib/jvm/java-6-openjdk/jre/man/man1/java.1.gz

So I'd like to understand a bit about why there is this runaround, if I am to try to understand Java even a little bit. Which I don't now.

Regards, John