Java: Combining "not" clauses in regex

Question

I'm trying to find a substring that contains a "]" without a "|" in front of it. How can I possibly do this with regex?

Answer 1

/(?<!\|)\]/ is the regex you need.

?<! is a zero-width assertion also known as "negative lookbehind." This essentially means match ], but "look behind" and assert that the previous character isn't a |

Answer 2

/(?<!\|)\]/

Use negative lookbehind.

For java :

Pattern regex = Pattern.compile("(?<!\\|)\\[");