Question

I’m trying to match an email address here is what I’ve come up with so far :

String text = "[e-mail]"; 
String regex = "(\\w+)@{1}(\\w+){2,}\\.{1}\\w{2,4}";

This however works with following cases :

[e-mail]
[e-mail]
[e-mail]

So it matches any alphanumeric character repeated once or more that comes before one @ followed by any alphanumeric character repeated at least two times(which is minimal characters for any domain name) followed by one .(dot) and followed by any alphanumeric character repeated at least 2 times and at most 4 times(because there are domains such as .us or .mobi).

This expression however does not work with emails such as :

[e-mail]
[e-mail]
[e-mail]
[e-mail]
etc as many subdomains

or

[e-mail]
[e-mail]
[e-mail]
[e-mail]

I’ve just started to learn regex and I found interesting to try to solve problems such as these by using regex .. not partially but for each case, any help would be much appriciated. Thank you

Answer 1

This question has been asked many, many times before here on SO. Here’s why you don’t want to use regexes
to parse email addresses. Note please that that monster of a regex doesn’t even handle comments.