Question regarding generics typing how would I guarantee the

Question

Question regarding generics typing how would I guarantee the properties parameters I pass into `ScreenInitSettings` are of type `LoginScreenState` which extends `ScreenState` Posting extra context in the thread ```fun Navigation initLoginScreen params LoginScreenParams = ScreenInitSettings title = Login Screen initState = LoginScreenState isLoading = true callOnInit = update state after retrieving data from the repository stateManager updateScreen lt LoginScreenState gt it copy isLoading = false reinitOnEachNavigation = false callOnInitAlsoAfterBackground = false ```

Josh Eldridge · Answer

```class ScreenInitSettings val title String val initState ScreenIdentifier gt ScreenState val callOnInit suspend StateManager gt Unit val reinitOnEachNavigation Boolean = false val callOnInitAlsoAfterBackground Boolean = false ```

Josh Eldridge · Answer

```interface ScreenState data class LoginScreenState val isLoading Boolean = false val serverName String = val serverList List lt String gt = emptyList ScreenState```

Josh Eldridge · Answer

I ran into this issue because I had accidentally passed in a different screen state type of `HomeFeedState` into `initState` and it resulted in a runtime error instead of compile time If I change `ScreenInitSettings` to use a generic type with an upper bound ```class ScreenInitSettings lt T ScreenState gt val title String val initState ScreenIdentifier gt T ``` It works but Android studio tells to remove the explicit type but if I accidentally use the wrong type it properly corrects me and no longer wants to remove it I guess my overall question is am I doing it right or is there a better way to do it so Android Studio doesn t recommend remove the type annotation

Gleb Minaev · Answer

AS as well as IDEA suggests to remove explicit ` lt LoginScreenState gt ` only because it can infer it from input arguments So usually it is sensible to remove it But if you are afraid to mix up the type you want to use then it is sensible to mark the function return type Or you can ignore the suggestion to remove the explicit type usage And even add proper `Suppress` annotation via shortcut Alt+Enter then suppress

Josh Eldridge · Answer

Thanks