Before looking at how Groovy improves on the handling of the regular expression, I round out the Java example that was started above to also include an example of Java’s Matcher class in action ...

For example, in the (Java( language)) regex, ( language) nests inside (Java). Each nested or non-nested capturing group receives its own number, numbering starts at 1, and capturing groups are ...

Given an input string s and a pattern p, implement regular expression matching with support for '.' and '*' where: '.' Matches any single character. '*' Matches zero or more of the preceding element.