Different objects have the same hashCode

[StefanZlobin]

Hello everyone. Faced with the problem that two different objects have the same hashCode. Provided an example below. How to make sure that the hashCode is also different for different objects? (The override of equals and hashCode is in the generated files). The objects differ in the Map value in MenuDishModifiers.

Example:

final x1 = MenuDish(
    id: '1',
    code: '1',
    dishName: '1',
    category: '1',
    isActive: true,
    price: 1,
    needsModifiers: true,
    unique: true,
    dishModifiers: [
      MenuDishModifiers(
        maxCount: 1,
        minCount: 1,
        modifiers: {
          const Modifiers(
            id: '1',
            name: '1',
            count: 1,
          ): true,
          const Modifiers(
            id: '2',
            name: '2',
            count: 1,
          ): false,
        },
      ),
      MenuDishModifiers(
        maxCount: 1,
        minCount: 1,
        modifiers: {
          const Modifiers(
            id: '3',
            name: '3',
            count: 1,
          ): true,
          const Modifiers(
            id: '4',
            name: '4',
            count: 1,
          ): false,
        },
      ),
    ],
  );

  final x2 = MenuDish(
    id: '1',
    code: '1',
    dishName: '1',
    category: '1',
    isActive: true,
    price: 1,
    needsModifiers: true,
    unique: true,
    dishModifiers: [
      MenuDishModifiers(
        maxCount: 1,
        minCount: 1,
        modifiers: {
          const Modifiers(
            id: '1',
            name: '1',
            count: 1,
          ): false,
          const Modifiers(
            id: '2',
            name: '2',
            count: 1,
          ): true,
        },
      ),
      MenuDishModifiers(
        maxCount: 1,
        minCount: 1,
        modifiers: {
          const Modifiers(
            id: '3',
            name: '3',
            count: 1,
          ): false,
          const Modifiers(
            id: '4',
            name: '4',
            count: 1,
          ): true,
        },
      ),
    ],
  );

  print(x1 == x2);
  print(x1.hashCode);
  print(x2.hashCode);

Output result to the console:

I/flutter (24401): false
(2) I/flutter (24401): 515360140

My classes are provided below.

@freezed
class MenuDish with _$MenuDish {
  const factory MenuDish({
    required String id,
    required String code,
    required String dishName,
    required String category,
    required bool isActive,
    required double price,
    required bool needsModifiers,
    List<MenuDishModifiers>? dishModifiers,
    String? dishComment,
    required bool unique,
  }) = _MenuDish;
}

@Freezed(makeCollectionsUnmodifiable: false)
class MenuDishModifiers with _$MenuDishModifiers {
  const factory MenuDishModifiers({
    required int maxCount,
    required int minCount,
    required Map<Modifiers, bool> modifiers,
  }) = _MenuDishModifiers;
}

@freezed
class Modifiers with _$Modifiers {
  const factory Modifiers({
    required String id,
    required String name,
    String? uni,
    double? price,
    @Default(1) int count,
  }) = _Modifiers;

  const Modifiers._();
}

[rrousselGit]

How to make sure that the hashCode is also different for different objects?

What are you trying to achieve here? Hashcodes aren't guaranteed to be unique for different objects. All objects could return the same hashCode if they wanted to.