public String toString(int maxNumber) {
   Collections.sort(associationRules);
   StringBuffer buffer = new StringBuffer("Association Rules" + Tools.getLineSeparator());
   int counter = 0;
   for (AssociationRule rule : associationRules) {
     if ((maxNumber >= 0) && (counter > maxNumber)) {
       buffer.append("... " + (associationRules.size() - maxNumber) + " other rules ...");
       break;
     }
     buffer.append(rule.toString());
     buffer.append(Tools.getLineSeparator());
     counter++;
   }
   return buffer.toString();
 }