Hi everyone, I'm relatively new at rule development and I'm having a problem tryin' to implement one in particular. I need to capture some events that they've got the same AttributeA and got more than 9 AttributeB Objects (excluding one type in particular) in one or more events. *Model:* Class Event { Long id; AttributeA attributeA; List<AttributeB> listAttributeB; Date timestamp; Long duration; } Class AttributeA { Long id; double doubleValue; String name; } Class AttributeB { Long id; String name; String someString; Boolean flag; } class AttributeBMock { //it doesn't have any of "one_type_of_attB" public List<AttributeB> getTenAttributeB() { return Arrays.asList(new AttributeB(000001L, 23.4, "random_string_1"), new AttributeB(000006L, 38.9, "random_string_2"), new AttributeB(000005L, 35.2, "random_string_3"), new AttributeB(000003L, 32.5, "random_string_4"), new AttributeB(000006L, 32.5, "random_string_5"), new AttributeB(000007L, 23.4, "random_string_6"), new AttributeB(0000012L, 23.4, "random_string_7"), new AttributeB(000015L, 44.4, "random_string_8"), new AttributeB(000010L, 87.0, "random_string_9"), new AttributeB(000010L, 87.0, "random_string_10")); } } ----------------------------------------------------------------------------------- *Test:* public void someMethod() { SessionPseudoClock clock = (SessionPseudoClock) ruleEngine.getClock(); clock.advanceTime(10, TimeUnit.SECONDS); //Just with this insertion i get the ArrayOutOfBounds exception ruleEngine.addEvent(new Purchase(123456L,new AttributeA(), AttributeBMock.getTenAttributeB(),new Date(clock.getCurrentTime(),0L)); Assert.assertTrue("The rule hasn't been fired", Assert.assertFalse("The rule hasn't been fired", ruleEngine.getEventListener().getExecutedRulesNames().containsAll(EXPECTED_RULES_NAMES)); } ------------------------------------------------------------------------------------------------------- *Rule:* when $event: event($attributeA : attributeA, attributeA.flag == true, $listAttributeB : listAttributeB) from entry-point "some_entry_point" $quantity: List() from collect($attributeB : attributeB(name != 'one_type_of_attB') from $listAttributeB) Number(doubleValue > 9) from accumulate(event(attributeA == $attributeA) from entry-point "some_entry_point", sum($quantity.size)) then System.out.println("Event: " + $event.id ); end ----------------------------------------------------------------- Everytime when I fire an event that triggers the rule, the accumulate method throws an "ArrayOutOfBounds" exception. I don't know why, the logic looks good to me. Can I get some help, please? Thx. in advance Regards -- View this message in context: http://drools.46999.n3.nabble.com/Rule-triggering-problem-with-Drools-tp4... Sent from the Drools: User forum mailing list archive at Nabble.com.