OptaPlanner multiple entity classes with chained variables

Question

I'm using OptaPlanner to solve a variant of a Vehicle routing problem in which the requirements of the customers to be served by vehicles vary significantly. I have a few most common customer types and want to model them using different entity classes. As it's possible for a single driver to attend different types, they should be able to form heterogeneous chains with instances of all classes on them.

I tried to do a proof of concept by modifying the VRP example. I extracted ICustomer, an interface for all my customers and changed the Standstill so that getNextCustomer returns an ICustomer. When I try to run it with Customer and Customer2 (a copy of the customer class), both implementing ICustomer, I get this error:

Exception in thread "main" java.lang.IllegalArgumentException: The entityClass 
(interface org.optaplanner.examples.vehiclerouting.domain.Standstill) has a 
InverseRelationShadowVariable annotated property (nextCustomer) with a masterClass 
(interface org.optaplanner.examples.vehiclerouting.domain.ICustomer) which is not a 
valid planning entity.

In the worst case, I'll just model different customer types with enums and "ifs" in a single planning entity to get the same behaviour. Still, would be great to know if I encountered an API limitation or someone knows a better way to achieve this. Thanks :)

Geoffrey De Smet Geoffrey De Smet · Accepted Answer · 2017-09-19T08:06:06

OptaPlanner fully supports polymorfism, class hierarchies, etc. We have tests for it (and have regularly found bugs for it which have been solved - as recently as for 7.3.final IIRC). See also TestDataSolution.java and the like. New reproducers are welcome as PR's of course.

The exception tells a different story. Check where you use @InverseRelationShadowVariable, the return type of that field/method - I suspect your refactor might not have impacted that code correctly.

OptaPlanner multiple entity classes with chained variables

1 Answers