java regular expression digits, letters, uppercase, lowercase

Question

I need a regular expression in Java with the following requirements:

I have tried several expressions that don't work - this is the best so far:

(?=.*\\d)(?=.*[a-z])(?=.*[A-Z]).*

http://stackoverflow.com/questions/3802192/regexp-java-for-password-validation — assylias, May 05 '14 at 13:59
The problem is with this requirement: can only contain letters and digits. The current regex accepts other characters - and it must not — me72921, May 05 '14 at 14:02

score 3 · Accepted Answer · answered May 05 '14 at 14:04

3

Anchor your regex, and don't use . which allows anything:

^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])[a-zA-Z0-9]*$

^$ matches beginning and end of string, [a-zA-Z0-9]* makes sure the characters are only those in the character class.

answered May 05 '14 at 14:04

Robin

1 Answers1