Groovy supports regular expressions natively using the ~"..." expression. Plus Groovy supports the =~ (create Matcher) and ==~ (matches regex) operators. e.g.

assert "cheesecheese" =~ "cheese"

// lets create a regex Pattern
pattern = ~"foo"
assert pattern instanceof Pattern
assert pattern.matcher("foo").matches()

// lets create a Matcher
matcher = "cheesecheese" =~ "cheese"
assert matcher instanceof Matcher
answer = matcher.replaceAll("edam")

// lets do some replacement
cheese = ("cheesecheese" =~ "cheese").replaceFirst("nice")
assert cheese == "nicecheese"