GPJaSI is a project mainly written in JAVA and PERL, it's free.
gprolog Java Simple Interface
GPJaSI - gprolog (gnu prolog) Java Simple Interface
Prolog interfaces for java are hard to configure and use. Some are old and deprecated, other ahave many bugs. This is a new Java interface, created from scratch, and all you need is to have "gprolog" command accessible in your path.