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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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.)

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

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]")

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

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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