I have a `SubjectTeacherPeriod` object which has a property `strAttributeMap` which is a map of `String` and `List<String>`. I want to check if `HardConstraint.strAttributeValue` and `SubjectTeacherPeriod.strAttributeMap[$attribute]` *intersect*. Here is the rule: rule "hardConflictIsIn" when $hc : HardConstraint( $attribute : attribute, operator == "is in", $values : strAttributeValue, $period : period ) $stp : SubjectTeacherPeriod( period == $period, //ERROR IN FOLLOWING LINE Collections.disjoint(strAttributeMap[$attribute], $values) == false ) then insertLogical(new IntConstraintOccurrence("hardConflictIsIn", ConstraintType.NEGATIVE_HARD,1, $hc,$stp)); end But the rule (actually two of them) throws the error: Exception in thread "main" java.lang.IllegalStateException: There are errors in the scoreDrl's: Unable to Analyse Expression Collections.disjoint(strAttributeMap[$attribute], $values) == false: sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl cannot be cast to java.lang.Class : [Rule name='hardConflictIsIn'] Unable to Analyse Expression Collections.disjoint(strAttributeMap[$attribute], $values) == true: sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl cannot be cast to java.lang.Class : [Rule name='hardConflictNotIn'] at org.drools.planner.config.solver.SolverConfig.buildRuleBase(SolverConfig.java:238) at org.drools.planner.config.solver.SolverConfig.buildSolver(SolverConfig.java:170) at org.drools.planner.config.XmlSolverConfigurer.buildSolver(XmlSolverConfigurer.java:103) at in.co.technovia.timetabler.TimeTableApp.createSolver(TimeTableApp.java:61) at in.co.technovia.timetabler.TimeTableApp.main(TimeTableApp.java:45) I got it from an answer from my own question at http://stackoverflow.com/a/9241089/604511 . Is this a bug in Drools itself? -- View this message in context: http://drools.46999.n3.nabble.com/Cant-check-complex-boolean-expressions-... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users