Could you please provide an example that
1) Loads a jar file into oracle [any permissions and path variables that needs to be set-up using DBAs help]
2) Load a class that uses the above jar file
3) Create a PL/SQL procedure or function that uses the above class file

I tried looking online and found multiple bits and pieces of information but there is no clear explanation of all the steps involved that can be followed. So if you could provide an example with a simple functionality, of a java class using jar files which can be invoked from PL/SQL, it would be great.