PDDL4J is an open source library to facilitate java implementation of planners based on the PDDL (Planning Description Language). The library contains a parser on the last version of PDDL 3.0 and an example of graphplan implementation.
N. Nejati, P. Langley, and T. Konik. ICML '06: Proceedings of the 23rd international conference on Machine learning, page 665--672. New York, NY, USA, ACM, (2006)