[jboss-jira] [JBoss JIRA] (DROOLS-349) Optaplanner rules NullPointerException

[Nick Snels (JIRA)]

Nick Snels created DROOLS-349:
---------------------------------

             Summary: Optaplanner rules NullPointerException
                 Key: DROOLS-349
                 URL: https://issues.jboss.org/browse/DROOLS-349
             Project: Drools
          Issue Type: Bug
      Security Level: Public (Everyone can see)
    Affects Versions: 6.0.0.CR1
         Environment: Windows 7 64 bit, Optaplanner 6.0.0.CR1, Java 1.7.0_17-b02
            Reporter: Nick Snels
            Assignee: Mark Proctor


I reported my issue with a Drools rule in Optaplanner on the Drools user forum (http://drools.46999.n3.nabble.com/Optaplanner-rules-NullPointerException-td4026875.html). I was adviced to create a JIRA ticket.

=============
I am trying to accomplish the following, a part time employee (eg 50%) needs to do only half the shifts a full time employee needs to do. I have created a rule, that 

1. count number of shifts of certain shiftType 
2. count number of shifts of a certain shiftType per employee 
3. count the total number of "arbeidsbreuken" per employee and within a certain shiftType 
4. do something with these numbers so that an part time employee only gets half the shifts assigned that a full time employee gets 

The complete rule is: 

rule "arbeidsbreuk" 
    when     
    //System.out.println("arbeidsbreuk, Drools!"); 
    ShiftAssignment($employee : employee, $shiftType : shiftType) 
    //count aantal shifts 
        $assignmentTotal : Number() from accumulate( 
            $assignment : ShiftAssignment(shiftType == $shiftType), 
            count($assignment) 
        ) 
        
        //count aantal shifts per medewerker 
        $assignmentTotalEmployee : Number() from accumulate( 
            $assignmentEmployee : ShiftAssignment(employee == $employee, shiftType == $shiftType), 
            count($assignmentEmployee) 
        ) 
        
        //count arbeidsbreuken van alle medewerkers 
        $arbeidsbreukTotal : Number() from accumulate( 
            //Employee($breuk : arbeidsbreuk), 
            ShiftAssignment(employee == $employee, shiftType == $shiftType), 
            sum($employee.getArbeidsbreuk()) 
        ) 
$assignmentTotalEmployee.intValue()) 
    then 
    System.out.println("Arbeidsbreuk drools: " + $employee.getArbeidsbreuk() + " - " + $assignmentTotal.intValue() + " - " + $assignmentTotalEmployee.intValue() + " - " + $arbeidsbreukTotal); 
        scoreHolder.addSoftConstraintMatch(kcontext, -(Math.abs(($employee.getArbeidsbreuk() * $assignmentTotal.intValue()) - $assignmentTotalEmployee.intValue()) * (Math.abs(($employee.getArbeidsbreuk() * $assignmentTotal.intValue()) - $assignmentTotalEmployee.intValue()))) ); 
end 

I get the following error: 

Exception in thread "main" org.drools.core.RuntimeDroolsException: java.lang.NullPointerException 
        at org.drools.core.rule.Accumulate.accumulate(Accumulate.java:182) 
        at org.drools.core.phreak.PhreakAccumulateNode.addMatch(PhreakAccumulateNode.java:756) 
        at org.drools.core.phreak.PhreakAccumulateNode.doLeftInserts(PhreakAccumulateNode.java:164) 
        at org.drools.core.phreak.PhreakAccumulateNode.doNode(PhreakAccumulateNode.java:81) 
        at org.drools.core.phreak.RuleNetworkEvaluator.switchOnDoBetaNode(RuleNetworkEvaluator.java:524) 
        at org.drools.core.phreak.RuleNetworkEvaluator.evalBetaNode(RuleNetworkEvaluator.java:494) 
        at org.drools.core.phreak.RuleNetworkEvaluator.innerEval(RuleNetworkEvaluator.java:277) 
        at org.drools.core.phreak.RuleNetworkEvaluator.outerEval(RuleNetworkEvaluator.java:161) 
        at org.drools.core.phreak.RuleNetworkEvaluator.evaluateNetwork(RuleNetworkEvaluator.java:116) 
        at org.drools.core.phreak.RuleExecutor.reEvaluateNetwork(RuleExecutor.java:205) 
        at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:65) 
        at org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:936) 
        at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1183) 
        at org.drools.core.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:935) 
        at org.drools.core.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:909) 
        at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:233) 
        at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.calculateScore(DroolsScoreDirector.java:98) 
        at org.optaplanner.core.impl.solver.scope.DefaultSolverScope.calculateScore(DefaultSolverScope.java:101) 
        at org.optaplanner.core.impl.bestsolution.BestSolutionRecaller.solvingStarted(BestSolutionRecaller.java:58) 
        at org.optaplanner.core.impl.solver.DefaultSolver.solvingStarted(DefaultSolver.java:177) 
        at org.optaplanner.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:154) 
        at be.ocmwturnhout.permanenties.Main.main(Main.java:495) 
Caused by: java.lang.NullPointerException 
        at be.ocmwturnhout.permanenties.solver.Rule_arbeidsbreuk654888368.accumulateExpression2(Rule_arbeidsbreuk654888368.java:23) 
        at be.ocmwturnhout.permanenties.solver.Rule_arbeidsbreuk654888368AccumulateExpression2Invoker.evaluate(Rule_arbeidsbreuk654888368AccumulateExpression2Invoker.java:25) 
        at org.drools.core.base.accumulators.JavaAccumulatorFunctionExecutor.accumulate(JavaAccumulatorFunctionExecutor.java:107) 
        at org.drools.core.rule.Accumulate.accumulate(Accumulate.java:173) 
        ... 21 more 

Any idea how I can solve this? Thanks. 

Kind regards, 

Nick

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