What are the Java regular expressions for matching IPv4 and IPv6 strings?

Question

Looking for a string to pass to String#matches(String) that will match IPv4, and another to match IPv6.

Answer 1

Another good option for processing IPs is to use Java's classes Inet4Address and Inet6Address, which can be useful in a number of ways, one of which is to determine the validity of the IP address.

I know this doesn't answer the question directly, but just thought it's worth mentioning.