JACK: A Java Constraint Kit
Slim Abdennadher, Ekkerhard Krämer, Matthias Saft, Matthias Schmauss
In Proc. of the International Workshop on Functional and (Constraint) Logic Programming (WFLP 2001)
, Report No. 2017, University of Kiel
Abstract
Most existing libraries providing constraint facilities are embedded
  in the logic programming language, Prolog, or in the object-oriented
  language, C++. Recently, some proposals have been made to integrate
  constraint handling in Java. The goal of this work is to provide a
  new constraint library for Java, called JACK. It consists of a
  high-level language for writing constraint solvers, a generic search
  engine and a tool to visualize the simplification and propagation of
  constraints.