Hi.
I think you should maybe do/find the thing you like most in Computer Science. This is a very large ground with big possibilities. You can do many, many things, like GUIs, web development, databases, data mining, software engineering, network administration, algorithms, bio-med, etc. etc.
If you find out what you like, then you can test what programming languages would be best for you. Knowing Java very good is really valuable, but I think it's also good practice to discover something else. To compare and evolve yourself. Then you will know that some things can be made simple and faster in one technology and other things in other technology. You can also start thinking out of the box.
I would advice to learn pure C, can be ANSI, to know some quite low level programming. You can compare the speed of programs written in C and Java.
I can tell you that if you know one programming language very good, then learning new one is quite simple. They taught me that when you know C, you also know other languages (well in real it's not so obvious).
Main thing is to stick to what you like most. To enjoy it :) Yes, enjoy it!
So I would suggest to learn functional language like C.
Best regards,
ventus
ps. sorry for not perfect English ;)