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> 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?
--
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