I am having the same problem as described in this post: http://www.nabble.com/The-effect-of-not-using-shadow-facts-tp11652637p117... The problem is, there really was no solution mentioned. Here is my collections class that I am asserting into working memory: public class NamedCollection<T> extends LinkedList<T>{ public NamedCollection(String name){ super(); this.name = name; } public String getName(){ return name; } /** * */ private static final long serialVersionUID = -457439174592908333L; private String name; @Override public int hashCode() { final int prime = 31; int result = super.hashCode(); result = prime * result + ((name == null) ? 0 : name.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (!super.equals(obj)) return false; if (getClass() != obj.getClass()) return false; final NamedCollection other = (NamedCollection) obj; if (name == null) { if (other.name != null) return false; } else if (!name.equals(other.name)) return false; return true; } } I get the following error when inserting this fact into memory: org.drools.RuntimeDroolsException: Error creating shadow fact for object: [] at org.drools.reteoo.Rete$ClassObjectTypeConf.getShadow(Rete.java:628) at org.drools.reteoo.Rete.assertObject(Rete.java:166) at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192) at org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java :71) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java :886) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java :858) at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java :60) at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java :54) at sequitem.quanteq.ruleflow.Rule_Explode_Globals_0.consequence (Rule_Explode_Globals_0.java:15) at sequitem.quanteq.ruleflow.Rule_Explode_Globals_0ConsequenceInvoker.evaluate (Rule_Explode_Globals_0ConsequenceInvoker.java:22) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:550) at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java :514) at org.drools.common.AbstractWorkingMemory.fireAllRules( AbstractWorkingMemory.java:462) at org.drools.common.AbstractWorkingMemory.fireAllRules( AbstractWorkingMemory.java:424) at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java :50) at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java :24) at sequitem.quanteq.rules.RandomMarketEntryRulesTest.testRandomMarketEntryRules (RandomMarketEntryRulesTest.java:56) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java :39) at sun.reflect.DelegatingMethodAccessorImpl.invoke( DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:232) at junit.framework.TestSuite.run(TestSuite.java:227) at junit.textui.TestRunner.doRun(TestRunner.java:116) at junit.textui.TestRunner.doRun(TestRunner.java:109) at junit.textui.TestRunner.run(TestRunner.java:77) at junit.textui.TestRunner.run(TestRunner.java:62) at sequitem.quanteq.rules.RandomMarketEntryRulesTest.main( RandomMarketEntryRulesTest.java:64) Caused by: java.lang.NullPointerException at java.util.LinkedList.clear(LinkedList.java:292)E at sequitem.quanteq.rules.engine.NamedCollectionShadowProxy.updateProxy (Unknown Source) at sequitem.quanteq.rules.engine.NamedCollectionShadowProxy.setShadowedObject (Unknown Source) at org.drools.reteoo.Rete$ClassObjectTypeConf.getShadow(Rete.java:626) ... 33 more Time: 67.75 There was 1 error: 1) testRandomMarketEntryRules( sequitem.quanteq.rules.RandomMarketEntryRulesTest )org.drools.spi.ConsequenceException: org.drools.RuntimeDroolsException: Error creating shadow fact for object: [] at org.drools.base.DefaultConsequenceExceptionHandler.handleException( DefaultConsequenceExceptionHandler.java:14) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:553) at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java :514) at org.drools.common.AbstractWorkingMemory.fireAllRules( AbstractWorkingMemory.java:462) at org.drools.common.AbstractWorkingMemory.fireAllRules( AbstractWorkingMemory.java:424) at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java :50) at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java :24) at sequitem.quanteq.rules.RandomMarketEntryRulesTest.testRandomMarketEntryRules (RandomMarketEntryRulesTest.java:56) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java :39) at sun.reflect.DelegatingMethodAccessorImpl.invoke( DelegatingMethodAccessorImpl.java:25) at sequitem.quanteq.rules.RandomMarketEntryRulesTest.main( RandomMarketEntryRulesTest.java:64) Caused by: org.drools.RuntimeDroolsException: Error creating shadow fact for object: [] at org.drools.reteoo.Rete$ClassObjectTypeConf.getShadow(Rete.java:628) at org.drools.reteoo.Rete.assertObject(Rete.java:166) at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192) at org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java :71) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java :886) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java :858) at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java :60) at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java :54) at sequitem.quanteq.ruleflow.Rule_Explode_Globals_0.consequence (Rule_Explode_Globals_0.java:15) at sequitem.quanteq.ruleflow.Rule_Explode_Globals_0ConsequenceInvoker.evaluate (Rule_Explode_Globals_0ConsequenceInvoker.java:22) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:550) ... 23 more Caused by: java.lang.NullPointerException at java.util.LinkedList.clear(LinkedList.java:292) at sequitem.quanteq.rules.engine.NamedCollectionShadowProxy.updateProxy (Unknown Source) at sequitem.quanteq.rules.engine.NamedCollectionShadowProxy.setShadowedObject (Unknown Source) at org.drools.reteoo.Rete$ClassObjectTypeConf.getShadow(Rete.java:626) ... 33 more _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users