Regex for matching something if it is not preceded by something else

java, regex

Solution

You want to use `negative lookbehind` like this:

\w*(?<!foo)bar

Where `(?<!x)` means "only if it doesn't have "x" before this point".

See Regular Expressions - Lookaround for more information.

Edit: added the `\w*` to capture the characters before (e.g. "beach").

Problem

With regex in Java, I want to write a regex that will match if and only if the pattern is not preceded by certain characters. For example: ``` String s = "foobar barbar beachbar crowbar bar "; ``` I want to match if `bar` is not preceded by `foo`. So the output would be: ``` barbar beachbar crowbar bar ```

Original source