Generic View Binding in Android Studio

user_11659881 0
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I'm in the process of writing abstract classes for a ListAdapter with a SelectionTracker<Long>. In my case, the SelectionTracker organizes items by selectionKeys via

interface TrackedListItem {

    var selectionKey : Long? 

}

Now, the items in the RecyclerView (and hence, the items stored in the ListAdapter) need to bind a "viewModel" (note this doesn't extend ViewModel, I'm just following the conventions outlined in Android Sunflower). Sticking with those same conventions, my ViewHolder should take a ViewBinding as its argument:

abstract class TrackedItemViewHolder(val binding: ViewBinding) : RecyclerView.ViewHolder(binding.root)

I know ahead of time that the binding passed to the ViewHolder has a data variable viewModel that I can bind to, and I will know that this viewModel implements TrackedListItem. How can I create a generic layout (and thus binding) that effectively just passes:

<data><variable
            name="viewModel"
            type="...TrackedListItem" /></data>
android-databinding kotlin android-layout xml
1 Answers

A reasonable workaround for anyone interested is to declare:

abstract class TrackedItemViewHolder(val binding: ViewBinding) : 
                                    RecyclerView.ViewHolder(binding.root){

    abstract val viewModel : TrackedListItem 
    ...

and then in implementations:

override val viewModel : TrackedListItem
    get() = (binding as bindingWithViewModel).viewModel!!
user_116598810
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