在 RecyclerView Adapter 中使用 ViewModel 的实时数据

Question

Recently had a circumstance where I had constantly observe the clicked view in a ViewHolder attached to a RecyclerView. I have tried setting onclick listener and for my bad it doesn't work out. Later something worked for me was passing a livedata to the adapter and posting the value to the livedata when click event is made on the view. It is as below.,

// live data
val selectedItem: MutableLiveData<String> by lazy { MutableLiveData<String>() }

// passing to adapter
binding.myRecycler.adapter = myAdapter(elements, myViewModel.selectedItem)

// adapter
class myAdapter(
    private val elements: List<Element>,
    private val selectedItem: MutableLiveData<String>,
) : RecyclerView.Adapter<myViewHolder>() {

    override fun onBindViewHolder(holder: myViewHolder, position: Int) {
        val element = elements[position]
        holder.card.setOnClickListener {
            selectedItem.postValue(element.uid)
        }
    }
}

I havent seen anyone recommending this way on most question about this in stackoverflow.

what are the drawbacks of passing live data to recyclerview adapter? when I observe the changes, it is working exactly the way I want. If this is not the correct way, what is the correct way to solve this?

My intention is to store the uid s of the clicked views in the adapter to a database,.

Answer 1

I think it`s not good idea for use viewModel and liveData to click event in android.
because use more observer in app not good.
the viewModel in android designed for work with activity and fragment and it use them lifecycle. click event is main thread process but post in live data is use for background calls.

the easiest way is use callback .
but if you use kotlin for developing android app you can use higher order function .

i hope the answer is true and help you