Re: [rules-users] How to use a result of custom defined function in WHEN part?

createCardinality must return a Collection. I think the simplest way of solving your problem is to write a simple class LetterCounter implementing the counting and a DRL function extracting the collection of Tuples from the LetterCounter: public class LetterCounter extends HashMap<Character,Integer> { public static Set<Map.Entry<Character,Integer>> counterSet( Collection<Character> l ){ return new LetterCounter( l ).entrySet(); } public LetterCounter( Collection<Character> chars ){ super(); for( Character c: chars ){ Integer count = get( c ); put( c, count == null ? 1 : count + 1 ); } } } rule "count" when $t: Something( $l: collectionOfLetters ) Map.Entry( $key: key, $val: value > 1 ) from LetterCounter.counterSet( $l ) then System.out.println( "letter " + $key + ": " + $val ); end -W On 18 December 2010 12:16, AleBu <aleboo(a)gmail.com&gt; wrote: > > Hi, > I am new to Drools and do some experiments on it, and encountered on a > problem which can't solve for a last few days, so maybe someone can > explain > what I am doing wrong? > I will probably explain my problem with example. Lets say we have a > collection of letters like 'a', 'b', 'c', 'a', 'd', 'e', 'c'. And I want > to > report all letters that are duplicated, but only once providing a number > of > duplication. In other words, for each letter which is duplicated I need to > do a report by saying 'Letter X is duplicated N times. > My idea was to create cardinality collection for letters which is a > collection of POJOs Tuple where first is letter and second is cound (first > and second are properties). I created a function for it createCardinality( > Collection letters ) which returns such cardinality info and tried > something > like: > when > Something( $letters: collectionOfLetters ) > Tuple( $letter: first, $count: second > 1 ) from collect( Tuple() > from > createCardinality( $letters ) ) > then > System.out.println( "Letter "+letter+" is duplicated "+$count+" > times" ) > > But I am reported (at least it looks like this) about the problems with my > function createCardinality(). Maybe I misunderstood something about usage > of > FROM? > -- > View this message in context: > http://drools-java-rules-engine.46999.n3.nabble.com/How-to-use-a-result-o... > Sent from the Drools - User mailing list archive at Nabble.com. > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users