communication between viewpager adapter and viewModel

Question

I used recyclerview inside viewpager. Now I want to change the view of my fragment when I scroll the recycler view. I am using mvvm and liveData and I want to use viewModel and send the scroll data to my viewModel and in view I observe the viewModel data that comes from viewPager adapter. How can I send the data from viewPager adapter and use them in its fragment?

val linearLayoutManager =
        LinearLayoutManager(container.context, LinearLayoutManager.VERTICAL, false)
    recCafeList = binding.recCafeList

    recCafeList.layoutManager = linearLayoutManager
    recCafeList.adapter = mAdapter



    recCafeList.setOnScrollListener(object : RecyclerView.OnScrollListener() {

        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
            super.onScrolled(recyclerView, dx, dy)

            val po = linearLayoutManager.findFirstVisibleItemPosition()
            val po2 = linearLayoutManager.findFirstCompletelyVisibleItemPosition()
            
            // I want to send @po and @po2 to viewModel and use them in fragment
            
            Log.i("scrollListener", "$po //// $po2")
        }

    })

    container.addView(binding.root)

    return binding.root

Answer 1

You can use custom Listener. Create it inside the fragment and transfer it to pagers adapter. And in any time you can call listeners method. Like that - Android communication between fragment and baseadapter

It is easy and nice practice solution.