Groovy supports regular expressions natively using the ~"..." expression. Plus Groovy supports the =~ (create Matcher) and ==~ (matches regex) operators. e.g.
import java.util.regex.Matcher
import java.util.regex.Pattern
assert "cheesecheese" =~ "cheese"
pattern = ~"foo"
assert pattern instanceof Pattern
assert pattern.matcher("foo").matches()
matcher = "cheesecheese" =~ "cheese"
assert matcher instanceof Matcher
answer = matcher.replaceAll("edam")
cheese = ("cheesecheese" =~ "cheese").replaceFirst("nice")
assert cheese == "nicecheese"
Since a Matcher coerces to a boolean by calling its find method, the =~ operator is consistent with the simple use of Perl's =~ operator, when it appears as a predicate (in 'if', 'while', etc.). The "stricter-looking" ==~ operator requires an exact match of the whole subject string.
(It would be nice to supply other Perl amenities, such as !~ and in-place edits of string variables. This is a job for someone familiar with the range of use cases, and their expressions in terms of Java Matchers. – John Rose.)