NPE in Drools org.drools.core.rule.SingleAccumulate.reverse(SingleAccumulate.java:124) --------------------------------------------------------------------------------------- Key: DROOLS-3066 URL: https://issues.jboss.org/browse/DROOLS-3066 Project: Drools Issue Type: Bug Components: core engine Affects Versions: 7.4.1.Final Environment: Windows 7 Oracle Java Development Kit 1.8.0_111 Eclipse Oxygen 3a Optaplanner 7.4.1.Final Reporter: Philip Harding Assignee: Luca Molteni Priority: Major Attachments: NPE_Drools_MWE.zip Original Estimate: 2 days Remaining Estimate: 2 days The rule {code:java} rule "globalRequiredPredecessorAfterMe" when $rpAll: Set(size>1) from accumulate ( Customer(Domicile != null, $rpAfterMe: requiredPredecessorsAfterMe); collectSet($rpAfterMe) ) then scoreHolder.addMediumConstraintMatch(kcontext, - $rpAll.size()-1); end {code} gives following NPE within the attached Optaplanner model: {code:java} Exception in thread "main" java.lang.RuntimeException: java.lang.NullPointerException at org.drools.core.rule.SingleAccumulate.reverse(SingleAccumulate.java:124) at org.drools.core.phreak.PhreakAccumulateNode.removeMatch(PhreakAccumulateNode.java:796) at org.drools.core.phreak.PhreakAccumulateNode.doRightUpdatesProcessChildren(PhreakAccumulateNode.java:517) at org.drools.core.phreak.PhreakAccumulateNode.doRightUpdates(PhreakAccumulateNode.java:450) at org.drools.core.phreak.PhreakAccumulateNode.doNode(PhreakAccumulateNode.java:76) at org.drools.core.phreak.RuleNetworkEvaluator.switchOnDoBetaNode(RuleNetworkEvaluator.java:581) at org.drools.core.phreak.RuleNetworkEvaluator.evalBetaNode(RuleNetworkEvaluator.java:552) at org.drools.core.phreak.RuleNetworkEvaluator.evalNode(RuleNetworkEvaluator.java:379) at org.drools.core.phreak.RuleNetworkEvaluator.innerEval(RuleNetworkEvaluator.java:339) at org.drools.core.phreak.RuleNetworkEvaluator.outerEval(RuleNetworkEvaluator.java:175) at org.drools.core.phreak.RuleNetworkEvaluator.evaluateNetwork(RuleNetworkEvaluator.java:133) at org.drools.core.phreak.RuleExecutor.reEvaluateNetwork(RuleExecutor.java:212) at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:87) at org.drools.core.concurrent.AbstractRuleEvaluator.internalEvaluateAndFire(AbstractRuleEvaluator.java:34) at org.drools.core.concurrent.SequentialRuleEvaluator.evaluateAndFire(SequentialRuleEvaluator.java:43) at org.drools.core.common.DefaultAgenda.fireLoop(DefaultAgenda.java:1067) at org.drools.core.common.DefaultAgenda.internalFireAllRules(DefaultAgenda.java:1014) at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1006) at org.drools.core.impl.StatefulKnowledgeSessionImpl.internalFireAllRules(StatefulKnowledgeSessionImpl.java:1337) at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1328) at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1312) at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.calculateScore(DroolsScoreDirector.java:117) at org.optaplanner.core.impl.score.director.AbstractScoreDirector.doAndProcessMove(AbstractScoreDirector.java:187) at org.optaplanner.core.impl.constructionheuristic.decider.ConstructionHeuristicDecider.doMove(ConstructionHeuristicDecider.java:126) at org.optaplanner.core.impl.constructionheuristic.decider.ConstructionHeuristicDecider.decideNextStep(ConstructionHeuristicDecider.java:100) at org.optaplanner.core.impl.constructionheuristic.DefaultConstructionHeuristicPhase.solve(DefaultConstructionHeuristicPhase.java:74) at org.optaplanner.core.impl.solver.AbstractSolver.runPhases(AbstractSolver.java:88) at org.optaplanner.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:191) at canihazafischbroetchenplz.app.TestApp.main(TestApp.java:35) Caused by: java.lang.NullPointerException at org.drools.core.base.accumulators.CollectSetAccumulateFunction.reverse(CollectSetAccumulateFunction.java:118) at org.drools.core.base.accumulators.CollectSetAccumulateFunction.reverse(CollectSetAccumulateFunction.java:49) at org.drools.core.base.accumulators.JavaAccumulatorFunctionExecutor.reverse(JavaAccumulatorFunctionExecutor.java:133) at org.drools.core.rule.SingleAccumulate.reverse(SingleAccumulate.java:116) ... 28 more {code}