Converting lowercase to capitals

[blastocyst]

I guess I'm going to use ascii values here, taking a string and converting all letters to lowercase. I'd rather use a for loop than a huge switch statement. How do I do this?

[server_crash]

String s = "lowercase";
String s2 = s.toUpperCase();

Remembers Strings are immutable so this won't work:
String s = "lowercase";
s.toUpperCase();