Android Studio – can we change textview being on same fragment?

I tried re-working with your code, but some things didn’t make sense, for example RecyclerViewAdapter.ob.dataSelected. Where are you getting the RecyclerViewAdapter instance from?

Hence, I’ve pasted below a snippet of an adapter code which I had written sometime ago which solves exactly the same purpose as you require.

class RecyclerViewAdapter(
    val interactionListener: InteractionListener,
    val onTextChangedListener: OnTextChangedListener
) : RecyclerView.Adapter<RecyclerViewAdapter.OptionViewHolder>() {

    private val variantsList = ArrayList<VariantsItem>()

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OptionViewHolder {
        val binding = SellVariantRowItemBinding.inflate(
            LayoutInflater.from(parent.context),
            parent,
            false
        )
        return OptionViewHolder(binding)
    }

    override fun onBindViewHolder(holder: OptionViewHolder, position: Int) {
        holder.bind(variantsList[position])
    }

    override fun getItemCount() = variantsList.size

    fun updateVariantsList(newList: ArrayList<VariantsItem>) {
        variantsList.clear()
        variantsList.addAll(newList)
        notifyDataSetChanged()
    }

    inner class OptionViewHolder(
        private val binding: SellVariantRowItemBinding
    ) : RecyclerView.ViewHolder(binding.root) {

        private var subVariant: String = ""

        @SuppressLint("SetTextI18n")
        fun bind(variantsItem: VariantsItem) {
            subVariant = variantsItem.subVariant

            binding.apply {
                binding.root.tag = "pos_$bindingAdapterPosition"
                sizeTv.text = "Size (${bindingAdapterPosition+1})"
                variantValue.text = variantsItem.variant
                subVariantValue.text = variantsItem.subVariant
                quantityET.setText(variantsItem.quantity.toString().takeIf { it != "0" }?:"1")
                sellingPriceET.setText(variantsItem.listingPrice.toString())
                marketPriceET.setText(variantsItem.labelPrice.toString())

                setOnClickListeners(variantsItem)
                setTextChangeListeners(variantsItem)

            }
        }

        private fun setTextChangeListeners(item: VariantsItem) {
            binding.apply {
                quantityET.addTextChangedListener {
                    if (it.toString().toIntOrNull() != null) {
                        onTextChangedListener.onQuantityChanged(
                            bindingAdapterPosition,
                            item.subVariant, item.variant,
                            it.toString()
                        )
                    }
                }

                marketPriceET.addTextChangedListener {
                    if (it.toString().toIntOrNull() != null) {
                        onTextChangedListener.onMarketPriceChanged(
                            bindingAdapterPosition,
                            item.subVariant,item.variant,
                            it.toString()
                        )
                    }
                }

                sellingPriceET.addTextChangedListener {
                    if (it.toString().toIntOrNull() != null){
                        onTextChangedListener.onSellingPriceChanged(
                            bindingAdapterPosition,
                            item.subVariant,item.variant,
                            it.toString()
                        )
                    }
                }
            }
        }

        private fun setOnClickListeners(variantsItem: VariantsItem) {
            binding.apply {
                deleteVariantBtn.setSafeOnClickListener {
                    interactionListener.onDeleteCard(variantsItem)
                }

                subVariantLayout.setSafeOnClickListener {
                    interactionListener.onChangeSubVariant(variantsItem)
                }
                variantLayout.setSafeOnClickListener {
                    interactionListener.onChangeVariant(variantsItem)
                }
                addNewVariant.setSafeOnClickListener {
                    it.pan()
                    interactionListener.onAddVariant(variantsItem.subVariant)
                }
            }
        }
    }

    interface InteractionListener{
        fun onChangeSubVariant(subToBeDeleted: VariantsItem)
        fun onChangeVariant(variant: VariantsItem)
        fun onDeleteCard(variant: VariantsItem)
        fun onAddVariant(subVariantValue: String)
    }

    interface OnTextChangedListener{
        fun onQuantityChanged(position: Int, subVariant: String, variant: String, quantity: String)
        fun onMarketPriceChanged(position: Int, subVariant: String, variant: String, price: String)
        fun onSellingPriceChanged(position: Int, subVariant: String, variant: String, price: String)
    }
}

Few things to note:

1. You cannot have a single binding instance to handle all of the items of the recycler view. We have the ViewHolder for this purpose.
2. Keep your binding logic and everything related to each individual item inside the ViewHolder. That’s what it is meant for.
3. Try keeping your adapter simple and only write presentation logic. Keep all of the business logic outside the adapter.
4. Interfaces are your best friends. This supports point 3. Make your activity / fragment implement these interfaces and pass the instance to the Adapter constructor as such val variantsAdapter = RecyclerViewAdapter(this, this). This will allow you to write your business logic outside the Recycler View adapter (Including context required statements like calling a different activity or starting a service or as in your case, making an API call)

Feel free to reach out in case you have any questions.