Where/How could I get a list of all the java and javac's error and warning messages?
Do you mean Java Exception?
http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Exception.html
This is a list of every exception that Java will at run-time. If you are refering to syntax errors you maybe look at learning Java
You could look through the source code, since it's open source.
But more importantly - I can't think of a single reason why you'd want to do this. What's your real question here; what are you trying to achieve? It's almost certain you're going about it in a suboptimal fashion...
mindprod.com has a Java Glossary with runtime and compile time lists:
http://mindprod.com/jgloss/errormessages.html
Hope that helps
This list of exceptions is much more interesting than any of the above answers.
It might not be as useful or as complete, but it's good reading nonetheless.