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Sonarlint regex

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  Sonarlint regex "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-02-10 08:48 -0800
    Re: Sonarlint regex Eric Sosman <donalhambra@gmail.com> - 2023-02-10 09:50 -0800
      Re: Sonarlint regex "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-02-10 10:22 -0800
        Re: Sonarlint regex Arne Vajhøj <arne@vajhoej.dk> - 2023-02-10 16:37 -0500

#39919 — Sonarlint regex

My app is passing in a user id. We're hard coding 4 users.
user01
user03
user05
user07
We have validation that the user passed in is one of these.
private void validateUser(String userId) {
if (!userId.matches("(user0)[1|3|5|7]")) {
throw new SecurityException("Invalid user");
}
}
This seems to work but Sonarlint flags the regex string with "Remove duplicates in this character class". Is there a better way to write the same thing?

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#39920

On Friday, February 10, 2023 at 11:48:12 AM UTC-5, e.d.pro...@gmail.com wrote:
> My app is passing in a user id. We're hard coding 4 users. 
> user01 
> user03 
> user05 
> user07 
> We have validation that the user passed in is one of these. 
> private void validateUser(String userId) { 
> if (!userId.matches("(user0)[1|3|5|7]")) { 
> throw new SecurityException("Invalid user"); 
> } 
> } 
> This seems to work but Sonarlint flags the regex string with "Remove duplicates in this character class". Is there a better way to write the same thing?

First, try logging in as "user0|".  Then ponder what happens. Then lose the "|" characters.
(You may also want to lose the "(" and ")", as they seem purposeless.)

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#39921

> > if (!userId.matches("(user0)[1|3|5|7]")) { 
> > throw new SecurityException("Invalid user"); 
> > } 
> > } 
> > This seems to work but Sonarlint flags the regex string with "Remove duplicates in this character class". Is there a better way to write the same thing?
> First, try logging in as "user0|". Then ponder what happens. Then lose the "|" characters. 
> (You may also want to lose the "(" and ")", as they seem purposeless.)
I see. I don't know who came up with that. Apparently the | was supposed to mean "or" but that's already the purpose of the [].
regex101 says the () makes a capturing group which matches the characters literally (case sensitive), apparently it does the same thing without the () but doesn't call it a capturing group.
so just .matches("user0[1357]")

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#39922

On 2/10/2023 1:22 PM, e.d.pro...@gmail.com wrote:
>>> if (!userId.matches("(user0)[1|3|5|7]")) { throw new
>>> SecurityException("Invalid user"); } } This seems to work but
>>> Sonarlint flags the regex string with "Remove duplicates in this
>>> character class". Is there a better way to write the same thing?
>> First, try logging in as "user0|". Then ponder what happens. Then
>> lose the "|" characters. (You may also want to lose the "(" and
>> ")", as they seem purposeless.)
> I see. I don't know who came up with that. Apparently the | was
> supposed to mean "or" but that's already the purpose of the []. 
> regex101 says the () makes a capturing group which matches the
> characters literally (case sensitive), apparently it does the same
> thing without the () but doesn't call it a capturing group. so just
> .matches("user0[1357]")

"user0[1357]" puts the entire username in group 0

"(user0)[1357]" puts the entire username in group 0
and "user0" in group 1 which does not make sense

"user(0[1357])" puts the entire username in group 0
and "0x" in group 1 which in some contexts could make sense

Arne

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