Access data from RecyclerView Item when visible on screen

Question

I am trying to access the underlying data from a recyclerview item when it scrolls onto the screen.

I am using onAttachedToRecyclerView() inside my Adapter class. Then get the data within onScrolled().

Here is what I have so far:

    override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
    super.onAttachedToRecyclerView(recyclerView)
    val manager = recyclerView.layoutManager
    Log.i("ProductAdapter","$manager")
    if (manager is StaggeredGridLayoutManager) {
        val slm: StaggeredGridLayoutManager = manager
        recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                super.onScrolled(recyclerView, dx, dy)
                val firstVisibleItemPosition: Int
                val firstVisibleItemPositions =
                    slm.findFirstVisibleItemPositions(null)
                firstVisibleItemPosition = firstVisibleItemPositions[0]
                if (firstVisibleItemPosition > -1) {
                    val item = getItem(firstVisibleItemPosition))
                    // do stuff with item data
                }
            }
        })
    }else{
        Log.e("ProductAdapter","error")
    }
}

when I set val manager = recyclerView.layoutManager, manager ends up being null. So the first if check never passes. My code is referencing this answer from another question. Any ideas on how to fix this?

Are you setting the ``LayoutManager`` on the ``RecyclerView`` **before** you set the ``Adapter``? — cactustictacs, Sep 22 '21 at 02:22

score 0 · Accepted Answer · answered Sep 22 '21 at 02:55

In my Fragment I was setting the adapter for the recyclerview one line before setting the layout manager.

Code before:

recyclerViewProducts.apply {
            this.adapter = productAdapter
            layoutManager = staggeredGridLayoutManager
            itemAnimator?.changeDuration = 0
        }

Code after:

recyclerViewProducts.apply {
            layoutManager = staggeredGridLayoutManager
            this.adapter = productAdapter
            itemAnimator?.changeDuration = 0
        }

Thanks to cactustictacs

Access data from RecyclerView Item when visible on screen

1 Answers1