How to Match Elements Without Preceding Characters Using Java Regular Expressions?

Regular Expression for Matching Elements Without Preceding Characters

In Java, regular expressions provide a powerful mechanism for matching patterns in a string. One common scenario is to identify patterns that are not preceded by specific characters. To achieve this, leverage negative lookbehind assertions.

For instance, let's consider the string:

String s = "foobar barbar beachbar crowbar bar ";

To match instances of "bar" that are not preceded by "foo", utilize the following regex:

\w*(?<!foo)bar

Explanation:

• w*: Matches any word character (alphanumeric and underscore) zero or more times.
• "(?

Applying this regex to string "s" produces the following matches:

barbar
beachbar
crowbar
bar

This demonstrates the selective matching of "bar" instances only when they are not preceded by "foo".

The above is the detailed content of How to Match Elements Without Preceding Characters Using Java Regular Expressions?. For more information, please follow other related articles on the PHP Chinese website!