regex - 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

public static final String IPV4_REGEX = "\A(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\z";
public static final String IPV6_HEX4DECCOMPRESSED_REGEX = "\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?) ::((?:[0-9A-Fa-f]{1,4}:)*)(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\z";
public static final String IPV6_6HEX4DEC_REGEX = "\A((?:[0-9A-Fa-f]{1,4}:){6,6})(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\z";
public static final String IPV6_HEXCOMPRESSED_REGEX = "\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)\z";
public static final String IPV6_REGEX = "\A(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}\z";

Got these from some blog. Someone good w/ regexes should be able to come up with a single regex for all IPv6 address types. Actually, I guess you could have a single regex that matches both IPv4 and IPv6.