2001:0DB8:0000:0000:0000:0000:1428:57ab
2001:0DB8:0000:0000:0000::1428:57ab
2001:0DB8:0:0:0:0:1428:57ab
2001:0DB8:0::0:1428:57ab
2001:0DB8::1428:57ab

//IPv6 address validator matches these IPv6 formats
//::ffff:21:7.8.9.221 | 2001:0db8:85a3:08d3:1319:8a2e:0370:7344
//| ::8a2e:0:0370:7344 | 2001:0db8:85a3:08d3:1319:8a2e:100.22.44.55
//| 2001:0db8::8a2e:100.22.44.55 | ::100.22.44.55 | ffff::
//And such addresses are invalid
//::8a2e:0:0370:7344.4 | 2001:idb8::111:7.8.9.111 | 2001::100.a2.44.55
//| :2001::100.22.44.55
public static boolean isIPV6Format(String ip) {
    ip = ip.trim();

    //in many cases such as URLs, IPv6 addresses are wrapped by []
    if(ip.substring(0, 1).equals("[") && ip.substring(ip.length()-1).equals("]"))

        ip = ip.substring(1, ip.length()-1);

        return (1 < Pattern.compile(":").split(ip).length)
        //a valid IPv6 address should contains no less than 1,
        //and no more than 7 ":” as separators
            && (Pattern.compile(":").split(ip).length <= 8)

        //the address can be compressed, but "::” can appear only once
            && (Pattern.compile("::").split(ip).length <= 2)

        //if a compressed address
            && (Pattern.compile("::").split(ip).length == 2)

            //if starts with "::” – leading zeros are compressed
            ? (((ip.substring(0, 2).equals("::"))
            ? Pattern.matches("^::([\\da-f]{1,4}(:)){0,4}(([\\da-f]{1,4}(:)[\\da-f]{1,4})
        |([\\da-f]{1,4})|((\\d{1,3}.){3}\\d{1,3}))", ip)
                : Pattern.matches("^([\\da-f]{1,4}(:|::)){1,5}
        (([\\da-f]{1,4}(:|::)[\\da-f]{1,4})|([\\da-f]{1,4})
        |((\\d{1,3}.){3}\\d{1,3}))", ip)))

        //if ends with "::" - ending zeros are compressed
                : ((ip.substring(ip.length()-2).equals("::"))
                ? Pattern.matches("^([\\da-f]{1,4}(:|::)){1,7}", ip)
                : Pattern.matches("^([\\da-f]{1,4}:){6}(([\\da-f]{1,4}
        :[\\da-f]{1,4})|((\\d{1,3}.){3}\\d{1,3}))", ip));
    }}

InetAddress inetAddr = InetAddress.getByName(ipAddr);
ipAddr = inetAddr.getHostAddress();
System.out.println(ipAddr);

public static String getLocalIPv6Address() throws IOException {
    InetAddress inetAddress = null;
    Enumeration<NetworkInterface> networkInterfaces = NetworkInterface
        .getNetworkInterfaces();
    outer:
    while (networkInterfaces.hasMoreElements()) {
        Enumeration<InetAddress> inetAds = networkInterfaces.nextElement()
        .getInetAddresses();
        while (inetAds.hasMoreElements()) {
            inetAddress = inetAds.nextElement();
            //Check if it's ipv6 address and reserved address
            if (inetAddress instanceof Inet6Address
                && !isReservedAddr(inetAddress)) {
                break outer;
            }
        }
    }

    String ipAddr = inetAddress.getHostAddress();
    // Filter network card No
    int index = ipAddr.indexOf('%');
    if (index > 0) {
        ipAddr = ipAddr.substring(0, index);
    }

    return ipAddr;
}

/**
 * Check if it's "local address" or "link local address" or
 * "loopbackaddress"
 *
 * @param ip address
 *
 * @return result
 */
private static boolean isReservedAddr(InetAddress inetAddr) {
    if (inetAddr.isAnyLocalAddress() || inetAddr.isLinkLocalAddress()
        || inetAddr.isLoopbackAddress()) {
        return true;
    }

    return false;
}

java.net.preferIPv4Stack=<true|false>
java.net.preferIPv6Addresses=<true|false>