String pattern which starts with # @ and can contain underscore and minus

I try to make a string pattern that can contain UTF-8 characters (öäå, etc) and match the following criteria in Java (1.7);

• Must start with # or @
• Must be lower-case
• Can contain – or _ (minus and underscore), no other special char
• Can contain digits (0-9)
• Min 3 and maximum 15 characters long

What I have at the moment that works but are missing many of the criteria.

“#p{javaLowerCase}+”

I don’t know how to complete and add the rest of the criteria. How would a regex expression look like that can accommodate the criteria I have?

Answer

This translates into a regex in a relatively simple way:

"[#@][\p{javaLowerCase}\d_-]{2,14}"

This translates the “Min 3 and maximum 15 characters” inclusive of the # or @ at the beginning. If these should not be counted, change the suffix to {3,15}.