Java Programming

I know this has been asked and I'm sorry. I've probably asked it myself but have forgotten the answer.

Given a US based character set is String.hashCode() guaranteed to return the same value for the same string across JVMs? I know that hashCode() can return the same value for different strings. I want to implement it in an update system where the client hashes it's value and sends it to the server. The server compares the hash (different JVMs) and if different sends a new value.

I'm choosing this methodology because the value being tested is very large. I figure the chances of a false positive (where the client and server value don't match but the hash does) to very low.

Thanks for your input(s)
ST