RE: [rules-dev] Dealing with null pointer exceptions thrown by parsing rules

Thanks for replying. rule "Player 1 wins first set " when $f : Fact() eval ($f.getDetails().get("END_SET").toString() == "true" && Integer.valueOf($f.getDetails().get("SET").toString()) == 1 && Integer.valueOf($f.getDetails().get("PLAYER1_SCORE").toString()) > Integer.valueOf($f.getDetails().get("PLAYER2_SCORE").toString())) then //then settle selection; end this rules runs perfectly as long as the hashmap contained in the 'fact' object has all the required keys and their values are not null. For the time being I have just changed any null values to a value of 'DEFAULT' but it would be preferable to be able to look for f.getDetails().get("END_SET") (for example) knowing that the engine that sent it might not be in an end_set state so may not have added that key. That example is very basic but as I create more rules for more sports it could become very cumbersome to have to ensure that every key referenced in the rules is in the hashmap each time! Alex ________________________________ From: rules-dev-bounces(a)lists.jboss.org [mailto:rules-dev-bounces@lists.jboss.org] On Behalf Of David Sinclair Sent: 24 February 2009 17:27 To: Rules Dev List Subject: Re: [rules-dev] Dealing with null pointer exceptions thrown by parsing rules I understand what you are saying Alex, but could you post an example rule to see exactly how you are doing it? It may be that you could simply rewrite the rule so you don't get the NPE. On Tue, Feb 24, 2009 at 4:24 AM, Zevenbergen, Alex <azevenbergen(a)paddypower.com&gt; wrote: Hi all, I have started writing my rules packages and so have had a decent amount of success. However all my rules are based on value pairs from a hashmap object that is contained within my fact object. This approach works fine if the parameter the rule is looking for is in the map and has a value. But I will need to be able to pass null values to the rules (and expect them to just not fire any rule that looks for that param), however this always throws a null pointer exception. So my question is: Is there any mechanism to deal with this in drools. Simply setting all nulls to a default value isn't preferable in this situation as the app is going to be used by several different sources and has to be able to take in many different types of info. Thanking you, Alex ________________________________________________________________________ Privileged, confidential and/or copyright information may be contained in this communication. This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the intended addressee, you may not copy, forward, disclose or otherwise use this e-mail or any part of it in any way whatsoever. To do so is prohibited and may be unlawful. If you have received this email in error please notify the sender immediately. Paddy Power PLC may monitor the content of e-mail sent and received for the purpose of ensuring compliance with its policies and procedures. Paddy Power plc, Airton House, Airton Road, Tallaght, Dublin 24 Registered in Ireland: 16956 ________________________________________________________________________ _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev ________________________________________________________________________ Privileged, confidential and/or copyright information may be contained in this communication. This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the intended addressee, you may not copy, forward, disclose or otherwise use this e-mail or any part of it in any way whatsoever. To do so is prohibited and may be unlawful. If you have received this email in error please notify the sender immediately. Paddy Power PLC may monitor the content of e-mail sent and received for the purpose of ensuring compliance with its policies and procedures. Paddy Power plc, Airton House, Airton Road, Tallaght, Dublin 24 Registered in Ireland: 16956 ________________________________________________________________________