Re: [rules-users] Null Pointer Exception in "org.drools.reteoo.RuleTerminalNode.retractTuple"

Hi - me again :-( Unfortunately I receive a NPE (3.1-M1) as follows (a complete JAR illustrating the problem is available):- **Java Man man=*new* Man(); Machine machine=*new* Machine(); Process p =* new* Process(); wm.assertObject(man); wm.assertObject(machine); wm.assertObject(p); **Rules *package* drools.debug *rule* "Rule-1" *no-loop** true* *when* $p : Process() *then* System.out.println("DEBUG [Rule-1]---> Add ProcessAlternative to Process"); ProcessAlternative pa =* new* ProcessAlternative(); $p.addProcessAlternative(pa); * assert*(pa); * modify*($p); *end* *rule* "Rule-2" *no-loop** true* *when* $m : Machine() *then* System.out.println("DEBUG [Rule-2]---> Add Machine to MachineEntry"); MachineEntry me =* new* MachineEntry(); me.setMachine($m); * assert*(me); *end* *rule* "Rule-3" *no-loop** true* *when* $me : MachineEntry() $pa : ProcessAlternative() *then* System.out.println("DEBUG [Rule-3]---> Add MachineEntry to ProcessAlternative"); $pa.addMachineEntry($me); * modify*($pa); *end* //rule "Rule-4 (Null Pointer Exception)" //no-loop true //when // $h : Man ( ) // $m : Machine ( ) // $mte : MachineEntry ( machine == $m ) //then // System.out.println("DEBUG [Rule 4]---> Assigned resource"); // $m.setManualResource($h); // modify($m); //end **Output DEBUG [Rule-1]---> Add ProcessAlternative to Process DEBUG [Rule-2]---> Add Machine to MachineEntry DEBUG [Rule-3]---> Add MachineEntry to ProcessAlternative This is what I'd expect. If however rule "Rule-4" is uncommented the output is:- DEBUG [Rule-1]---> Add ProcessAlternative to Process DEBUG [Rule-2]---> Add Machine to MachineEntry DEBUG [Rule-3]---> Add MachineEntry to ProcessAlternative DEBUG [Rule 4]---> Assigned resource DEBUG [Rule-2]---> Add Machine to MachineEntry <-- Why activated? no-loop is true DEBUG [Rule 4]---> Assigned resource <-- Presumably activated as a consequence of above And I receive a NPE with the following stack trace:- _java.lang.NullPointerException_ at org.drools.reteoo.RuleTerminalNode.retractTuple(_RuleTerminalNode.java:267_) at org.drools.reteoo.SingleTupleSinkAdapter.propagateRetractTuple(_SingleTupleSinkAdapter.java:38_) at org.drools.reteoo.JoinNode.retractTuple(_JoinNode.java:217_) at org.drools.reteoo.SingleTupleSinkAdapter.propagateRetractTuple(_SingleTupleSinkAdapter.java:38_) at org.drools.reteoo.JoinNode.retractObject(_JoinNode.java:183_) at org.drools.reteoo.CompositeObjectSinkAdapter.propagateRetractObject(_CompositeObjectSinkAdapter.java:369_) at org.drools.reteoo.ObjectTypeNode.retractObject(_ObjectTypeNode.java:189_) at org.drools.reteoo.Rete.retractObject(_Rete.java:171_) at org.drools.reteoo.ReteooRuleBase.retractObject(_ReteooRuleBase.java:215_) at org.drools.reteoo.ReteooWorkingMemory.doRetract(_ReteooWorkingMemory.java:76_) at org.drools.common.AbstractWorkingMemory.modifyObject(_AbstractWorkingMemory.java:940_) at org.drools.base.DefaultKnowledgeHelper.modifyObject(_DefaultKnowledgeHelper.java:95_) at drools.debug.Rule_Rule_4__Null_Pointer_Exception__0.consequence(_Rule_Rule_4__Null_Pointer_Exception__0.java:8_) at drools.debug.Rule_Rule_4__Null_Pointer_Exception__0ConsequenceInvoker.evaluate(_Rule_Rule_4__Null_Pointer_Exception__0ConsequenceInvoker.java:24_) at org.drools.common.DefaultAgenda.fireActivation(_DefaultAgenda.java:467_) at org.drools.common.DefaultAgenda.fireNextItem(_DefaultAgenda.java:431_) at org.drools.common.AbstractWorkingMemory.fireAllRules(_AbstractWorkingMemory.java:360_) I have also encountered NPE in "org.drools.reteoo.AlphaNode.retractObject" when using my actual rules other than these simplifications put together to demonstrate the error (both are caused by a call to "final Activation activation = tuple.getActivation();" returning NULL so I suspect the root cause to be common). Is this a case for a new JIRA entry or have I done something idiotic? With kind regards, Mike ------------------------------------------------------------------------ _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users