What the actual mean of "The Planning list variable (Resource.jobList variable) of entity (my-resource-01) is null" ?

[kentbill]

Hi teams,
I use the PlanningListVariable with DSV in my code, and I got a message, what does the actual mean of "The Planning list variable (Resource.jobList variable) of entity (my-resource-01) is null" ?

What does its actual mean? The entity "my-resource-01" is null?

The full message below:
java.lang.IllegalStateException: The planning list variable (PrimaryResource.jobList variable) of entity (1.ProductionLine-04) is null.
at ai.timefold.solver.core.impl.domain.variable.descriptor.ListVariableDescriptor.getValue(ListVariableDescriptor.java:157)
at ai.timefold.solver.core.impl.domain.variable.ExternalizedListVariableStateSupply.insert(ExternalizedListVariableStateSupply.java:63)
at ai.timefold.solver.core.impl.domain.entity.descriptor.EntityDescriptor.lambda$visitAllEntities$15(EntityDescriptor.java:853)
at ai.timefold.solver.core.impl.domain.solution.descriptor.SolutionDescriptor.visitEntitiesByEntityClass(SolutionDescriptor.java:1141)
at ai.timefold.solver.core.impl.domain.entity.descriptor.EntityDescriptor.visitAllEntities(EntityDescriptor.java:852)
at ai.timefold.solver.core.impl.domain.variable.ExternalizedListVariableStateSupply.resetWorkingSolution(ExternalizedListVariableStateSupply.java:59)
at ai.timefold.solver.core.impl.domain.variable.listener.support.AbstractNotifiable.resetWorkingSolution(AbstractNotifiable.java:75)
at ai.timefold.solver.core.impl.domain.variable.listener.support.VariableListenerSupport.resetWorkingSolution(VariableListenerSupport.java:229)
at ai.timefold.solver.core.impl.score.director.AbstractScoreDirector.setWorkingSolution(AbstractScoreDirector.java:252)
at ai.timefold.solver.core.impl.score.director.stream.BavetConstraintStreamScoreDirector.setWorkingSolution(BavetConstraintStreamScoreDirector.java:63)
at ai.timefold.solver.core.impl.solver.scope.SolverScope.setWorkingSolutionFromBestSolution(SolverScope.java:335)
at ai.timefold.solver.core.impl.solver.AbstractSolver.solvingStarted(AbstractSolver.java:59)
at ai.timefold.solver.core.impl.solver.DefaultSolver.solvingStarted(DefaultSolver.java:222)
at ai.timefold.solver.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:193)
at ai.timefold.solver.core.impl.solver.DefaultSolverJob.call(DefaultSolverJob.java:128)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
at java.base/java.lang.Thread.run(Thread.java:1570)

Many thanks!

[kentbill]

I got the cause, the Planning variable list must be constructed before starting to solve.

[triceo]

Yes, exactly - it's not the entity that's null, it's the variable that holds the list. The list must not be null. It may be empty, just not null.