Looks like an NPE in your rule. Maybe maintenanceSlot or something is null.
You should raise an issue with drools-core (drools expert) that it should give a better runtime error to show on which line it NPE'ed. With kind regards, Geoffrey De Smet dweppenaar schreef: > Hi. > > I am experiencing the following exception: > org.drools.RuntimeDroolsException: Exception executing ReturnValue > constraint org.drools.rule.returnvaluerestrict...@a5f6c234 : > java.lang.NullPointerException. > > The rule that is causing the exception to occur is the following: > > rule "spreadOvertime" > > when > $violatingTask : > MaintenanceTask(eval(maintenanceSlot.getAvailability() == 1), motor != null, > maintenanceTechnician != null, $overtimeTaskID : id); > > ArrayList( $numberOfViolations : size ) from collect( > MaintenanceTask( > id == ($overtimeTaskID + 1) || > id == ($overtimeTaskID + 2) || > id == ($overtimeTaskID - 1) || > id == ($overtimeTaskID - 2), > eval(maintenanceSlot.getAvailability() >= 1) ) ); > > then > insertLogical(new IntConstraintOccurrence("spreadOvertime", > ConstraintType.NEGATIVE_SOFT, > $numberOfViolations, $violatingTask, $numberOfViolations)); > //System.out.println("Rule Fired: spreadOvertime ( number of > violations:" + $numberOfViolations + " for task " + $violatingTask + ")"); > > end > > The purpose of the rule is to spread the closer to normal maintenance > shifts. > > Just to clarrify what the objects are: > > MaintenanceTask: Consists of a MaintenanceSlot, MaintenanceTechnician and > Motor > MaintenanceSlot: Day, Timeslot, Availability and Index > > The 'availability' of a MaintenanceSlot specifies whether it is considered > Overtime, ProductionTime or Normal Maintenance > > This exception is thrown at the end of solving as the solver (I presume) is > supposed to return the best solution. The score is calculating and updating > but at the end of the specified step count, this exception occurs. > > If I comment this rule out, no exception. > > Any help would be appreciated! > > Regards, > De Ville _______________________________________________ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users