Get root domain from request

Question

Consider the below URL as an example. http://www.test1.example.com

Is there any method by which I can get \"example.com\" as an output. I know there is

Answer 1

You can do this as a simple String manipulation:

String A = "http://www.test1.example.com";
String B = A.substring(A.lastIndexOf('.', A.lastIndexOf('.')-1) + 1);

There is no standard way obtain example.com from a.b.c.example.com because such a transformation is generally not useful. There are TLDs that don't allow registrations on the second level; for example all .uk domains. Given news.bbc.co.uk you'd want to end up with bbc.co.uk, right?