How to optimize viewModel factories code?

Question

I have abstract class BaseViewmodel(uiActions: UiActions) : ViewModel(), UiActions by uiActions
All ViewModels in project extends BaseViewModel For example, 2 of my ViewModels (without bodies):

class SearchViewModel(uiActions: UiActions) : BaseViewModel(uiActions)

class HistoryViewModel(uiActions: UiActions) : BaseViewModel(uiActions)

All viewModels does NOT have any arguments except uiActions: UiActions So, factories are almost similar, difference is in class name only. For example:

class SearchViewModelFactory(private val uiActions: UiActions) : ViewModelProvider.Factory {

    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel?> create(modelClass: Class<T>): T =
        SearchViewModel(uiActions = uiActions) as T
}

class HistoryViewModelFactory(private val uiActions: UiActions) : ViewModelProvider.Factory {

    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel?> create(modelClass: Class<T>): T =
        HistoryViewModel(uiActions = uiActions) as T
}

Can I create 1 factory and use it everywhere?

Answer 1

You can write a factory that can be used for multiple different ViewModel types. That why the create function has a Class parameter:

class UiActionsViewModelFactory(private val uiActions: UiActions) : ViewModelProvider.Factory {
    
    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel?> create(modelClass: Class<T>): T = when (modelClass) {
        SearchViewModel::class.java -> SearchViewModel(uiActions)
        HistoryViewModel::class.java -> HistoryViewModel(uiActions)
    }

}

I'm not sure about what UiActions is, but be careful to avoid leaking any view/activity/fragment references to the ViewModel.