[rules-users] Drools Expert does not sort integers correctly

John Smith ffirstt.llastt at gmail.com
Thu Jan 17 06:15:07 EST 2013


I am new to Drools and am trying to get the sample program to work. This
sample is given in the drools documentation
http://docs.jboss.org/drools/release/5.5.0.Final/drools-expert-docs/html_single/index.html#d0e9542.
This drool rule is expected to sort integers. I just changed the numbers
from what are given in the sample and they do not get sorted as expected.
Tried using drools version 5.5.0, 5.5.1 and the master 6.0.0, but got the
same wrong results.

Following is the main code:
    package com.sample;

    public class Example2 {
      public static void main(String[] args) throws Exception {
        Number[] numbers = new Number[] { wrap(5), wrap(6), wrap(4),
wrap(1), wrap(2) };
        new RuleRunner().runRules(new String[] { "Example3.drl" }, numbers);
      }

      private static Integer wrap(int i) {
        return new Integer(i);
      }
    }

 The RuleRunner class is the same as given in the example and I do not think
I should give that here, since it will clutter the question. It simply
creates the KnowledgeBase, stateful session, inserts the facts as given in
the 'numbers' array above and then calls fireAllRules method on the session.

The rule file (Example3.drl) is:


 rule "Rule 04"
     dialect "mvel"
   when
     $number : Number()
     not Number(intValue < $number.intValue)
   then
     System.out.println("Number found with value: " + $number.intValue());
     retract($number);
 end


The output I get is as follows:
Loading file: Example3.drl
Inserting fact: 5
Inserting fact: 6
Inserting fact: 4
Inserting fact: 1
Inserting fact: 2
Number found with value: 1
Number found with value: 4
Number found with value: 2
Number found with value: 5
Number found with value: 6

Not the correct expected ascending sorted order.

What might I be doing wrong? I cannot imagine that the drools rule engine
would be broken at this basic level.



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