In the world of Java, we have ANTLR and JavaCC;

In the world of Scala, we have Scala's own Parser Combinator, furthermore, we have more choices, for example, "kiama"( http://code.google.com/p/kiama/ ) from google code:

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Kiama is a  Scala  library for language processing. It enables convenient analysis and transformation of structured data. The programming styles supported by the library are based on well-known formal language processing paradigms, including attribute grammars and tree rewriting.

Kiama is a project of the  Programming Languages Research Group  in the  Department of Computing  at  Macquarie University  and is led by  Tony Sloane  (inkytonik).