how can I solve this ‘no args’ issue

what are you parsing it with? GSON?

yes

You could try using InstanceCreator like GSON docs suggest, but GSON + Kotlin is not an ideal combination, I'd either use jackson with kotlin module registered or kotlin-specific lib, like klaxon or koshi

Why don't you make it enum class then?

Another problem here is

val type: MenuTypeModel

serializer will try to instantiate the parent instead of

MAP

,

CALENDAR

or

LEADERBOARD

which you probably want.

I am trying to avoid using enum in Android as it is recommended by many not to use enums

It is recommended not to use Enums only to save up on memory and CPU when you can do the same thing with a constant, by using sealed classes you are defeating the purpose of avoiding enums

oh.

yeah, use of enum in this case is (probably) lighter than sealed classes 🙂 In the future always check why something is or isn't recommended.

In general It’s completely fine to use Enums on Android. If Enum or Sealed class solves your problem just use it. At least it’s more type safe than StringDef