Firebase Recyclerview (вертикальная прокрутка) всегда прокручивается до начала при нажатии кнопки возврата из другого действия

Question

Не уверен, почему такое поведение, но почти все перепробовал, дайте мне знать, если вы знаете об исправлении проблемы. Когда я вернусь из SellerAddNewProductActivity, нажав кнопку «Назад», затем RecyclerView всегда прокручиваю до начала

class SellerHomeFragment : Fragment() {
    private var searchInputText:String = ""
    private var sellerProductsViewListRecyclerView: RecyclerView? = null
    private var layoutManager: RecyclerView.LayoutManager? = null
    private var scroll_state: Parcelable? = null
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val root = inflater.inflate(R.layout.fragment_seller_home, container, false)
        sellerProductsViewListRecyclerView = root.findViewById(R.id.seller_products_view_list)
        layoutManager = LinearLayoutManager(this.context)
        sellerProductsViewListRecyclerView?.layoutManager = layoutManager
        val searchText: EditText = root.findViewById(R.id.seller_search_product_name)
        val searchProductsBtn: Button = root.findViewById(R.id.seller_search_products_btn)
        val sellerViewByProductState: Spinner = root.findViewById(R.id.seller_view_by_product_state)
        sellerViewByProductState.setSelection(0)
        searchProductsBtn.setOnClickListener {
            searchInputText = searchText.text.toString()
            createProductRecyclerView()
        }
        sellerViewByProductState?.onItemSelectedListener = object : AdapterView.OnItemSelectedListener{
            override fun onNothingSelected(parent: AdapterView<*>?) {
            }

            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
                createProductRecyclerView()
            }

        }
        return root
    }

    override fun onResume() {
        super.onResume()
        if(scroll_state!=null){
            sellerProductsViewListRecyclerView!!.layoutManager!!.onRestoreInstanceState(scroll_state)
        }
    }

    override fun onPause() {
        super.onPause()
        scroll_state = sellerProductsViewListRecyclerView!!.layoutManager!!.onSaveInstanceState()
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        createProductRecyclerView()
    }

    private fun createProductRecyclerView() {
        var productRef: DatabaseReference = FirebaseDatabase.getInstance().reference.child(
            PRODUCTS_DB_NAME
        )
        var options: FirebaseRecyclerOptions<Products>? = null
        val sellerViewByProductState: Spinner =
            requireView().findViewById(R.id.seller_view_by_product_state)
        val selectedProductState = sellerViewByProductState.selectedItem.toString()
        options = FirebaseRecyclerOptions.Builder<Products>().setQuery(
            productRef.child(selectedProductState).orderByChild(SID_PROPERTY)
                .equalTo(FirebaseAuth.getInstance().currentUser!!.uid), Products::class.java
        ).setLifecycleOwner(this).build()
        val adapter = object : FirebaseRecyclerAdapter<Products, ProductViewHolder>(options) {
            override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProductViewHolder {
                return ProductViewHolder(
                    LayoutInflater.from(parent.context)
                        .inflate(R.layout.product_items_layout, parent, false)
                )
            }

            protected override fun onBindViewHolder(
                holder: ProductViewHolder,
                position: Int,
                model: Products
            ) {
                holder.txtProductName.text = model.pname
                holder.txtProductDescription.text = model.description
                holder.txtProductPrice.text = "Price = ₹ " + model.price.toString()
                val context = holder.itemView.context
                Picasso.with(this@SellerHomeFragment.context).load(model.image).networkPolicy(
                    NetworkPolicy.OFFLINE
                ).tag(context).into(holder.imageView,
                    object : Callback {
                        override fun onSuccess() {
                        }

                        override fun onError() {
                            Picasso.with(this@SellerHomeFragment.context).load(model.image)
                                .into(holder.imageView)
                        }
                    })
                holder.itemView.setOnClickListener {
                    val intent: Intent = Intent(
                        this@SellerHomeFragment.context,
                        SellerAddNewProductActivity::class.java
                    )
                    intent.putExtra("category", model.category)
                    intent.putExtra("pid", model.pid)
                    val sellerViewByProductState: Spinner =
                        requireView().findViewById(R.id.seller_view_by_product_state)
                    val existingProductState = sellerViewByProductState.selectedItem.toString()
                    intent.putExtra("existingProductState", existingProductState)
                    startActivity(intent)
                }
            }
        }
        sellerProductsViewListRecyclerView?.setAdapter(adapter)
        adapter.startListening()
    }
}

Answer 1

Я не уверен, что понимаю ваш код, но я думаю, что если вы вызовете функцию setAdapter (адаптер) после добавления продукта, вы перезагрузите адаптер. Когда вы добавляете элемент в адаптер, используйте функцию notifyItemInserted () или notifyItemRangeInserted (позиция, диапазон) на адаптере.