How to get soon-to-be-selected page while settling snapping feature on RecyclerView and ViewPager

Question

Background

ViewPager snaps to a view after you perform some scrolling, and so can RecyclerView, if you use something like this:

Answer 1

Seems that for ViewPager, I could use the onPageSelected callback to get which item it's about to settle on.

So here's the solution for ViewPager (using the library I used) :

    val inflater = LayoutInflater.from(this)
    val viewPagerHolders = HashMap()
    viewPager.adapter = object : RecyclerPagerAdapter() {

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewPagerViewHolder {
            return ViewPagerViewHolder(inflater.inflate(R.layout.cell, parent, false))
        }

        override fun getItemCount(): Int = 100

        override fun onBindViewHolder(holder: ViewPagerViewHolder, position: Int) {
            holder.textView.text = position.toString()
            viewPagerHolders.remove(holder.adapterPosition)
            holder.adapterPosition = position
            viewPagerHolders[position] = holder

        }
    }
    viewPager.addOnPageChangeListener(object : ViewPager.OnPageChangeListener {
        var selectedHolder: ViewPagerViewHolder? = null

        override fun onPageScrollStateChanged(state: Int) {}
        override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {}

        override fun onPageSelected(position: Int) {
            val holder = viewPagerHolders[position]
            if (holder != null) {
                if (selectedHolder != null && selectedHolder != holder)
                    selectedHolder!!.textView.text = selectedHolder!!.adapterPosition.toString()
                holder.textView.text = "selected:${position.toString()}"
                selectedHolder = holder
            }
        }
    })

And a ViewHolder class that just remembers which adapter position is associated with it (because this is missing for some reason) :

class ViewPagerViewHolder(itemView: View) : RecyclerPagerAdapter.ViewHolder(itemView) {
    val textView: TextView = itemView.findViewById(android.R.id.text1)
    var adapterPosition: Int = Int.MIN_VALUE
}

Since it works so well, I decided I will use it, even without blocking touch events functionality.

Still could be nice to know how to do it for RecyclerView.

EDIT: for RecyclerView, this can be done: https://stackoverflow.com/a/47580753/878126