Dolmen is a generator of lexical analyzers and parsers for the Java programming language. It will produce lexical analyzers (resp. syntactic analyzers) based on textual lexer descriptions (resp. grammar descriptions). Dolmen can be used declaratively, as a library, to produce lexers and parsers from descriptions, or more commonly as a command-line tool. There also exists a dedicated Eclipse plug-in for Dolmen.
Documentation for Dolmen is available here.