code: public ComparableItemListImpl<Item> withComparator(@Nullable Comparator<Item> comparator, boolean sortNow) {
          this.mComparator = comparator;
  
          //we directly sort the list with the defined comparator
          if (mItems != null && mComparator != null && sortNow) {
              Collections.sort(mItems, mComparator);
              getFastAdapter().notifyAdapterDataSetChanged();
          }
  
          return this;
      }
docs: define a comparator which will be used to sort the list "everytime" it is altered
  NOTE this will only sort if you "set" a new list or "add" new items (not if you provide a position for the add function)
  
  @param comparator used to sort the list
  @param sortNow    specifies if we use the provided comparator to sort now
  @return this