Conditional capturing in java regex

Question

I am trying to figure out how to write the following regex:

assume I can have two types of strings to check and find "value":

string1: CONST1:CONST2:CONST3:value and

string2: CONST1:CONST2:CONST4:value-12345

For string1 this pattern would do

CONST1:CONST2:(CONST3|CONST4):(.*)

where I capture the second group. But I also need to handle the case when "value" is followed by the dash and some other value. I tried it this way:

CONST1:CONST2:(CONST3|CONST4):(.*)(-.*)?

But then second group (.*) will capture everything in string2, including following dash + value2 (12345). Making it (.*?) won't work either, for string1 group2 would return empty String.

Can anyone point me in what direction should I look to find the solution? Should I dig into lookahead and lookbehind or there is a simpler solution?

Thanks in advance.

JF Meier · Accepted Answer · 2016-07-06 09:42:57Z

1

Don't use

(.*), but

([^\-]*)

to avoid - in the result.

It is often better to avoid the dot . but give a positive or negative list of allowed characters.

answered Jul 6, 2016 at 9:42

JF Meier

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Community · Accepted Answer · 2020-06-20 09:12:55Z

1

^CONST1:CONST2:(CONST3|CONST4):([^\-\W]*)(-[^\W]+)?

Example:

https://regex101.com/r/vL4uG2/2

I tested the regex with the follow text:

CONST1:CONST2:CONST3:hola

CONST1:CONST2:CONST3:hola-43

CONST1:CONST2:CONST4:hola

CONST1:CONST2:CONST4:hola-12345

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jul 6, 2016 at 10:04

Troncador

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