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Java Constraint Programming (JaCoP) solver

JaCoP solver is Java-based open source solver developed and maintained mainly by two people

  • Krzysztof Kuchcinski, Dept. of Computer Science, Lund University, Sweden.
  • Radoslaw Szymanek -, Switzerland.

Moreover a number of students have contributed to the solver by programming first versions of different global constraints and set constraints. The solver is being used in academia for research and teaching as well as in industry for commercial purposes. The most successful use of the solver is within Electronic Design Automation community, since both main authors come from that community.

JaCoP provides a significant number of constraints to facilitate modeling as well as modular design of search. This allows to tailor search to characteristics of the problem being addressed. It has currently more than 90,000 lines of code, not including examples and testing code. The examples which are the preferred way to document the abilities of JaCoP have more than 20.000 lines of code. The core developers have been working on JaCoP for past 10 years during their free time as a hobby activity. It has been refactored, transformed, and improved many times. Initial versions of JaCoP were even 3 orders of magnitude slower than the current version. JaCoP implementation has been influenced heavily by more than 20 research articles. Moreover, JaCoP was used as a tool to conduct experiments for CP publications. JaCoP supports finite domains of integers and sets of integers.

The major focus of JaCoP are its constraints. These constraints include rich set of primitive, logical, and conditional constraints as well as many global constraints. The most important global constraints are as follows.

  • diff2,
  • cumulative,
  • alldifferent,
  • gcc,
  • extensional support (with three different state-of-the-art approaches)and extensional conflict,
  • among,
  • element,
  • circuit,
  • knapsack,
  • regular,
  • netflow, and
  • geost.

JaCoP solver contains also front-end for FlatZinc language that makes it possible to execute MiniZinc models. It allows us to perform extensive testing with the help of other solvers as we can compare results from different solvers.

JaCoP is an ongoing activity. We are working on it in our free time. The most recent addition is Scala based DSL so it is easier to create your own constraint programs even in more intuitive manner.

JaCoP is also available from maven repository. For details, please check INSTALL file.


We can only accept contributions (pull/merge requests) with signed Contributions License Agreement. Please read the document CLA_JaCoP in doc directory. Please use the checkstyle provided also in doc directory. Please make pull/merge requests only to develop branch. We do not accept other pull requests.

Installation Guide

The easiest way to make jar file for JaCoP is to use maven. First, install maven on your computer and then write

mvn install -DskipTests

The jar file will be generated into directory jacop/target.

Compilation of JaCoP can be easily done by issuing the following command

mvn compile

Generation of Java API documentation

mvn javadoc:javadoc

Generation of Scala formatted API documentation for Java and Scala

mvn scala:doc

Installation using Maven

To use JaCoP with maven you can just include it as a dependency in your pom.xml


From the version 4.4.0, JaCoP is uploaded to Maven Central so the above is the only thing you need to do.

For older versions of JaCoP (4.3 and older) you also need to add the following information about CSLTH Maven repository to your pom.xml as well

		<name>CS LTH maven repo</name>

Getting started

Probably the easiest way to start is to clone this repo. Afterwards, open the Maven project in IDE like Intelij IDEA and run examples available in directory $PATH_TO_GIT_REPO\src\main\java\org\jacop\examples.

Afterwards, you can copy parts of the provided examples into your own project add JaCoP maven dependency and start writing your own constraint programming examples.


It is provided in a separate file We can also provide JaCoP under different commercial license if open source license is not appropriate for your usage.