How to get String url contains or start with 'www'?

Question

i know how to get url regex of Url with 'http'. but what if i dont have 'http' and the url start with 'www'? How can i get the regex?

String urlRegex = "((https?):((//)|(\\\\))+[\\w\\d:#@%/;$()~_?\\+-=\\\\\\.&]*)";