Regex validating eight or more char string that must contain at least two non-alphabetic characters

Question

I am validating a password string that must consist of eight characters or more and must contain at least two non-alphabetic (i.e., not A-Za-z) characters using regular expression.

The code I have so far is

Pattern p = Pattern.compile("((?=2.*[^a-z[A-Z]]).{8,})");
    Matcher m = p.matcher(pass);

I don't know whether my expression is correct.

*i dont know whether my expression is correct*: then you should test it before asking. — JB Nizet, Jul 22 '18 at 08:23
maybe this can help you [`^(?=.*?[a-zA-Z])(?=.*?[^a-zA-Z]{2,}).{8,}$`](https://regex101.com/r/R4Bv0h/1) beside you can test your regex in this web site https://regex101.com/ — Youcef LAIDANI, Jul 22 '18 at 08:27
In that expression if I add numeric character the expression doesn't count it as an non alphabetic character — Samasha, Jul 22 '18 at 08:51
it do https://regex101.com/r/434gvx/1 can you please share some correct inputs please? — Youcef LAIDANI, Jul 22 '18 at 08:54
You should read [Reference - Password Validation](https://stackoverflow.com/questions/48345922) — ctwheels, Aug 21 '18 at 14:20

Wiktor Stribiżew · Answer 1 · 2018-07-22T11:21:31.100

I want to validate my password with eight characters or more and must contain at least two non-alphabetic (i.e., not A-Z) characters

You may use

s.matches("(?=(?:[^a-zA-Z]*[a-zA-Z]){2}).{8,}")

See the regex demo.

Another way of writing the same

s.matches("(?=.{8})(?:[^a-zA-Z]*[a-zA-Z]){2}.*")

Explanation

^ - (not necessary in .matches as the method requires a full string match) - start of string
(?= - start of a positive lookahead that requires, immediately to the right of the current location,
- (?:[^a-zA-Z]*[a-zA-Z]){2} - a non-capturing group that matches 2 consecutive occurrences of:
  - [^a-zA-Z]* - any 0+ chars other than ASCII letters
  - [a-zA-Z] - an ASCII letter
) - end of the lookahead
.{8,} - any 8 or more chars other than line break chars, as many as possible
$ - (not necessary in .matches as the method requires a full string match) - end of string

In (?=.{8})(?:[^a-zA-Z]*[a-zA-Z]){2}.* pattern, the first lookahead requires at least 8 chars, then at least two letters are requires using the (?:[^a-zA-Z]*[a-zA-Z]){2} pattern, and then .* matches the rest of the string.

Regex validating eight or more char string that must contain at least two non-alphabetic characters

1 Answers1