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

```
```
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.