output: #fixed code
                                @Override
    public int compare(Solution o1, Solution o2) {
      if (o1 == null) {
        return 1;
      } else if (o2 == null) {
        return -1;
      }
  
      int flagComparatorRank = RANK_COMPARATOR.compare(o1, o2);
      if (flagComparatorRank != 0) {
        return flagComparatorRank;
      }
      
      /* His rank is equal, then distance crowding RANK_COMPARATOR */
      double distance1 = NSGAIIAttr.getAttributes(o1).getCrowdingDistance() ;
      double distance2 = NSGAIIAttr.getAttributes(o2).getCrowdingDistance() ;
      //double distance1 = (double)o1.getAlgorithmAttributes().getAttribute("CrowdingDistance");
      //double distance2 = (double)o2.getAlgorithmAttributes().getAttribute("CrowdingDistance");
      if (distance1 > distance2) {
        return -1;
      }
  
      if (distance1 < distance2) {
        return 1;
      }
  
      return 0;
    }
input: #vulnerable code 
                                @Override
    public int compare(Solution o1, Solution o2) {
      if (o1 == null) {
        return 1;
      } else if (o2 == null) {
        return -1;
      }
  
      int flagComparatorRank = RANK_COMPARATOR.compare(o1, o2);
      if (flagComparatorRank != 0) {
        return flagComparatorRank;
      }
      
      /* His rank is equal, then distance crowding RANK_COMPARATOR */
      double distance1 = (double)o1.getAlgorithmAttributes().getAttribute("CrowdingDistance");
      double distance2 = (double)o2.getAlgorithmAttributes().getAttribute("CrowdingDistance");
      if (distance1 > distance2) {
        return -1;
      }
  
      if (distance1 < distance2) {
        return 1;
      }
  
      return 0;
    } 
                              #location 15 
                              #vulnerability type NULL_DEREFERENCE