Hi, this is my code: rule "Check activity" when riga : RigaAttivita($d : codice) r: ArrayList(size > 0) from collect (RigaAttivitaExcel(codice == $d ) ) then System.out.println("dimension "+r.size()); end I would fill every arraylist with all the object that have the same value of the field (codice) Using this code i get a loop... What i'm wrong???? Thanks -- View this message in context: http://www.nabble.com/using-%27from-collect%27-to-get-a-list-of-object-wi... Sent from the drools - user mailing list archive at Nabble.com.