I’ve a list as part of state (data class) I’m maintaining inside a viewModel. This state is being ob...

# android

[Kshitij Patil]

I’ve a list as part of state (data class) I’m maintaining inside a viewModel. This state is being observed by the UI components and updated accordingly. I also want to be able to edit/delete an element from this list but I can’t make the list mutable (As UI is supposed to consume it as immutable list) so everytime I need to do any modifications on that list, I go through

val newEntries = currentState().subEntries.toMutableList()
newEntries.remove(action.subEntry)
setState { copy(subEntries = newEntries.toList()) }

Are there any performance hits by doing it this way?

[Erik]

Wouldn't you be able to simplify that to the following?

setState { state.copy(subEntries = state.subEntries - action.subEntry) }

[Erik]

I.e.: use the minus operator on the existing list, which returns a new list

[Kshitij Patil]

Makes sense. I was concerned whether creating new list everytime is okay?

[Erik]

The minus operator also creates a new list, so it all depends on how often this code is called.