Regular Expression not matching

Question

I'm trying to create a RegExp to match new passwords (which works), but I only need a last step to make it work 100%.

Here's the RegExp and what it is supossed to:

((?=.*(\\d|[\\(\\)\\{\\}\\?!\\$&\\*%\\=\\+_\\-\\.]))(?=.*[a-z])(?=.*[A-Z]).{8,})

The RegExp says that: Digits OR Symbols (){}?!$&%*=+-. must be used -and that's what doesn't work, the OR operator, as I can insert both numbers and symbols-, at least one lowercase, at least one uppercase and a minimum lenght of 8 characters.

I've tried to use the OR operator | in several ways, but I can't make it work.

What am I missing? Thank you very much in advance.

Note: I'm using this regular expression within a liferay configuration file for the password policies.

To my knowledge, the OR operator in regex, like in most other situations, is inclusive, not exclusive, so it'll accept both as being ok. I could very well be wrong on this, not too familiar with regex. — MattS, Jul 12 '12 at 16:21
Note that you shouldn't escape the usual special characters in a character class (inside `[]`). The only special characters there are `]`, `\ `, `-` and `^`. — Keppil, Jul 12 '12 at 16:35

score 3 · Answer 1 · edited May 23 '17 at 12:20

3

You want a XOR logical operation, not a OR.

OR is true:
A |  B |  o/p
T |  T |   T
F |  T |   T
T |  F |   T
F |  F |   F

XOR is true:
A |  B | o/p
T |  T |  F
F |  T |  T
T |  F |  T
F |  F |  F

Exclusive Or in Regular Expression

edited May 23 '17 at 12:20

Community

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answered Jul 12 '12 at 16:23

Lee Louviere

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Keppil · Accepted Answer · 2012-07-13T08:07:12.630

3

Ok, I've rewritten your expression slightly, this is what I came up with:

String pattern = "^(?=.*[\\d().{}?!$&*%=+_-])(?=.*[a-z])(?=.*[A-Z]).{8,}$";

This matches any string with

at least one number or special character
at least one lower-case letter
at least one upper-case letter
is at least 8 characters long

edited Jul 13 '12 at 08:07

answered Jul 12 '12 at 16:54

Keppil

45,603
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score 2 · Answer 3 · answered Jul 12 '12 at 19:20

I have to say that, while regex can probably do this, I think it's simpler and safer to use multiple regex tests, something like:

boolean containsDigit = Pattern.matches("[0-9]", testString);
boolean containsSymbol = Pattern.matches("[(){}?!$&%*=+.-]", testString);
boolean containsLowercase = Pattern.matches("[a-z]", testString);
boolean containsUppercase = Pattern.matches("[A-Z]", testString);

if(testString.length() >= 8
        && containsLowercase
        && containsUppercase
        && (containsDigit || containsSymbol)
        && !(containsDigit && containsSymbol)) {
    //valid
} else {
    //invalid
}

I was using a Java regex pattern a few months ago that was not wildly complex, but it led to a Java bug being revealed. Too many parenthetic clauses seemingly caused trouble, and I had to split the pattern into something simpler.

The above is much more readable than a multi-clause regex pattern, and therefore easier to maintain and debug.

score 1 · Answer 4 · answered Jul 12 '12 at 16:24

You said,

I can insert both numbers and symbols

That would be normal with a logical OR operation. It sounds like what you want is exclusive or (XOR). I'm afraid I don't know how you do that in regex, but hopefully this will point you in the right direction.

Regular Expression not matching

4 Answers4