Java regex with a positive look behind of a negative look ahead

问题

I am trying to extract from this kind of string ou=persons,ou=(.*),dc=company,dc=org the last string immediately preceded by a coma not followed by (.*). In the last case, this should give dc=company,dc=org.

Looking on regex, this seems to be a positive look behind (preceded by) of a negative look ahead.

So I have achieve this regex: (?<=(,(?!.*\Q(.*)\E))).*, but it returns ,dc=company,dc=org with the coma. I want the same thing without the coma. What I am doing wrong?

回答1:

The comma appears because the capturing group contains it.

You can make the outside capture group noncapturing with (?:)

(?<=(?:,(?!.*\Q(.*)\E))).*

回答2:

It seems that I have solved my problem alone, removing the capturing group around the negative look ahead. It gives the following regex: (?<=,(?!.*\Q(.*)\E)).*.

It is linked with the behavior of capturing groups in look arounds as explained here: http://www.regular-expressions.info/lookaround.html in the part Lookaround Is Atomic.

来源：https://stackoverflow.com/questions/17814421/java-regex-with-a-positive-look-behind-of-a-negative-look-ahead