[rules-users] rule on Array of custom Object

hello, im using drools 5.0 on eclipse and i have a problem. i want to use an array of object in my rule condition. now i try to explain: i have my java class with the array attribute ------------------------------------------------- public static class Message { public numbers[] numbersArray; } -------------------------------------------- and the numbers class that rapresent the objects contained in numbersArray ---------------------------------------------- public static class numbers { public int first; public int last; } -------------------------------------------------- my goal is make a rule that check if Message.numbersArray[0].first="value" i use ------------------------------------------------- rule "rule_001" dialect "mvel" when $msg : Message(numbersArray[0].first=="1") then System.out.println("something...."); end ------------------------------- and on runtime it give me this error: --------------------------------------- org.drools.RuntimeDroolsException: Exception executing predicate numbersArray[0].first=="1" at org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:279) at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:143) at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:360) at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:344) at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:185) at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:146) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1046) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1001) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:788) at org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:216) at com.sample.DroolsTest.main(DroolsTest.java:47) Caused by: [Error: unable to access property (null parent): first] [Near : {... Unknown ....}] ^ [Line: 1, Column: 0] at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:861) at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getBeanProperty(ReflectiveAccessorOptimizer.java:585) at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:313) at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:138) at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:133) at org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:102) at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85) at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:107) at org.mvel2.MVEL.executeExpression(MVEL.java:978) at org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:75) at org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:272) ... 10 more ------------------------------------------------------- moreover if i try to print the "first" value: . . . then System.out.println(numbersArray[0].first); end appear this new error and i cant compile: "BuildError: Unable to build expression for 'consequence': Failed to compile: 1 compilation error(s): - (1,12) unqualified type in strict mode for: numbersArray' System.out.println(numbersArray[0].first); '" someone can kindly help me?