CODEWITHSUNDEEP
javaregexannotations
wybourn
wybourn

Reputation: 678

Java negative lookahead not working

I have the following regex ^(?!0{8}), which should match any string that isn't 8 zeros. I can't see why this isn't working. I.e, 12345678 does not match.

I need to use regex as I'm using this in a @Pattern annotation, so I can't just do an equality check.

I've tested it on this site https://regex101.com/ and it seems perfectly fine.

Any ideas?

Upvotes: 1

Views: 240

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626748

Your lookahead lacks the $ end of string anchor, and disallows matching any string starting with 8 zeros.

You need to use

^(?!0{8}$)
        ^

or - if the annotation pattern must match the entire string:

^(?!0{8}$).*$

Upvotes: 2

Dylan Meeus
Dylan Meeus

Reputation: 5802

You have made some mistakes in your regex. Checking if a string contains only 8 zeros. (According to your question, that is what you want to avoid) can be done with the regex "^(0{8})$". This regex will return true if there are 8 zeroes in a row, and that is the only content in the string. ^ matches the beginning and $matches the end.

You can use java to negate the result.

    String s = "123456789";
    System.out.println(!s.matches("^(0{8})$"));

Upvotes: 2

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