Java-8: how to sort a map (based on values) using Map.Entry # compareingByValue while ignoring case sensitivity?

Question

I want to sort the map based on values ​​in alphabetical order and ignore case sensitivity and return a list of keys.

 /**
   * This method will sort allCostPlanDetailsRows based on Value in <Key,Value> pair
   *
   * @param sortingOrder_ whether to sort the LinkedHashMap in Ascending order or Descending order
   * @return List<String> returns List of costPlanDetailsRowId in sorted order
   */
  private List<String> sortCostPlanDetailRows( SortingOrder sortingOrder_ )
  {
    return _allCostPlanDetailRows
      .entrySet()
      .stream()
      .sorted( sortingOrder_ == SortingOrder.DESC ? Map.Entry.<String, String>comparingByValue(Comparator.nullsFirst(Comparator.naturalOrder())).reversed() : Map.Entry.comparingByValue(Comparator.nullsFirst(
          Comparator.naturalOrder())) )
      .map( Map.Entry::getKey )
      .collect( Collectors.toList() );
  }

How can i achieve this?

Note: Suggestions are welcome if I can improve the code above.

Answer 1

Instead of using a comparator, naturalOrderyou can use String.CASE_INSENSITIVE_ORDER:

return _allCostPlanDetailRows
      .entrySet()
      .stream()
      .sorted( sortingOrder_ == SortingOrder.DESC ? Map.Entry.<String, String>comparingByValue(Comparator.nullsFirst(String.CASE_INSENSITIVE_ORDER)).reversed() : Map.Entry.comparingByValue(Comparator.nullsFirst(
          String.CASE_INSENSITIVE_ORDER)) )
      .map( Map.Entry::getKey )
      .collect( Collectors.toList() );