Get domain from hostname

gistfile1.txt

import com.google.common.net.InternetDomainName;
import java.net.URL;

public final class URLFunction {

    private static String getDomain(String url_input) {
        if (url_input.length() == 0) {
            return url_input;
        }

        URL url = new URL(url_input);
        String host = url.getHost();
        InternetDomainName domain_name = InternetDomainName.from(host).topPrivateDomain();
        return new String(domain_name);
    }
}