How can I prevent Recylerview from showing the recylerview from start again after deleting an item?

Question

I am building an app in which user can favourite some items.I am showing this in a recyclerview inside a fragment. User can also delete the item from favourite item list by clicking on delete button. The problem I am facing is that the if user delete and item at the end of the list the recylerview reloads and show from the start. I am using MVVM and using Livedata. Here is my code

FragmentFavorite.kt

class FavoriteFragment :Fragment() {


    lateinit var favoriteViewModel: FavoriteViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
    }

    override fun onAttach(context: Context) {
        super.onAttach(context)

    }

    override fun onCreateView(

        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        val v=inflater.inflate(R.layout.fragment_favorite,container,false)

        favoriteViewModel=ViewModelProvider(requireActivity()).get(FavoriteViewModel::class.java)

        val recylerview=v.findViewById<RecyclerView>(R.id.recylerviewFav)
        recylerview.layoutManager=LinearLayoutManager(requireContext(),RecyclerView.VERTICAL,false)


        favoriteViewModel.getAll(requireContext()).observe(requireActivity(), Observer {

            val adapter=FavoriteAdapter(it,requireContext(),object:FavoriteDeleteListener{
                override fun OnFavDelete(id: Int) {
                    favoriteViewModel.deleteFav(requireContext(),id)

                }

            })
            recylerview.adapter=adapter

        })



        return v
    }


}

RecylerviewAdapter.kt

class FavoriteAdapter(val list:List<Favorite>,context: Context,val listener:FavoriteDeleteListener) :RecyclerView.Adapter<FavoriteAdapter.MyViewholder> (){


    val listofFav=list.reversed()
    class MyViewholder(itemview: View):RecyclerView.ViewHolder(itemview) {
        val textview_src=itemview.findViewById<TextView>(R.id.textview_src)
        val textView_tar=itemView.findViewById<TextView>(R.id.textview_tar)
        val delte_fav=itemview.findViewById<ImageView>(R.id.delete_fav)
    }

    override fun onCreateViewHolder(
        parent: ViewGroup,
        viewType: Int
    ): FavoriteAdapter.MyViewholder {
      val v=LayoutInflater.from(parent.context).inflate(R.layout.fav_list,parent,false)

        return MyViewholder(v)

    }

    override fun onBindViewHolder(holder: FavoriteAdapter.MyViewholder, position: Int) {

        holder.textView_tar.text=listofFav[position].translated_text
        holder.textview_src.text=listofFav[position].text_to_translate

        holder.delte_fav.setOnClickListener {
            listofFav[position].fid?.let { it1 -> delete(it1,listener)
                notifyItemRemoved(position)
                }

        }





    }

    override fun getItemCount(): Int {

        return listofFav.size

    }

    fun delete(id:Int,listene: FavoriteDeleteListener) {
        listene.OnFavDelete(id)
    }
}

This answer should solve your problem - https://stackoverflow.com/a/32526482/3145960 — Reaz Murshed, Oct 21 '20 at 17:56

score 0 · Accepted Answer · answered Oct 21 '20 at 19:38

I suspect the problem is here:

favoriteViewModel.getAll(requireContext()).observe(requireActivity(), Observer {
    val adapter=...
    recylerview.adapter=adapter
})

If deleting an item from your dataset causes the observer to emit a new dataset, this will wind up re-assigning your RecyclerView's adapter, which will completely reset the view position.

You could use the ListAdapter component in order to compute a diff between the lists instead of completely overwriting the adapter everyt ime.

How can I prevent Recylerview from showing the recylerview from start again after deleting an item?

1 Answers1