IPv4/IPv6 network calculations and validation for Java?

Maybe CIDRUtils can help you. It enables you to convert CIDR notation to an IP range.

Disclaimer: I am the author of CIDRUtils.

It's only for IPv4, but the SubnetUtils class that is part of Commons Net has the functionality you are looking for. Based on that you could code up an IPv6 version and contribute it back to the project! :)