JaCoP - Java Constraint Programming solver
We have released our java constraint programming solver (JaCoP) under an open source license. Feel free to visit http://www.jacop.eu ( http://jacop.osolpro.com ). This solver comes with many examples, which give a nice introduction how to use Constraint Programming technology. If you wonder how to model Sudoku problem in 60 lines of Java code thanks to CP then you have to have a look at JaCoP and its examples.
JaCoP is used in teaching/research/industrial projects. It is continuously developed since 2000. JaCoP is only 60.000 lines of code but you would be surprised by its abilities to model and solve decision problems.