How to use ViewBinding in a RecyclerView.Adapter?

Can I use ViewBindings to replace findViewById in this typical RecyclerView.Adapter initialization code? I can't set a binding val in the object as the ViewHolders are different per cell.

class CardListAdapter(private val cards: LiveData<List<Card>>) : RecyclerView.Adapter<CardListAdapter.CardViewHolder>() {

    class CardViewHolder(val cardView: View) : RecyclerView.ViewHolder(cardView)

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

    override fun onBindViewHolder(holder: CardViewHolder, position: Int) {
        val title = holder.cardView.findViewById<TextView>(R.id.title)
        val description = holder.cardView.findViewById<TextView>(R.id.description)
        val value = holder.cardView.findViewById<TextView>(R.id.value)
        // ...
    }

Solution 1:

What you need to do is pass the generated binding class object to the holder class constructor. In below example, I have row_payment XML file for RecyclerView item and the generated class is RowPaymentBinding so like this

    class PaymentAdapter(private val paymentList: List<PaymentBean>) : RecyclerView.Adapter<PaymentAdapter.PaymentHolder>() {
        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PaymentHolder {
            val itemBinding = RowPaymentBinding.inflate(LayoutInflater.from(parent.context), parent, false)
            return PaymentHolder(itemBinding)
        }
    
        override fun onBindViewHolder(holder: PaymentHolder, position: Int) {
            val paymentBean: PaymentBean = paymentList[position]
            holder.bind(paymentBean)
        }
    
        override fun getItemCount(): Int = paymentList.size
    
        class PaymentHolder(private val itemBinding: RowPaymentBinding) : RecyclerView.ViewHolder(itemBinding.root) {
            fun bind(paymentBean: PaymentBean) {
                itemBinding.tvPaymentInvoiceNumber.text = paymentBean.invoiceNumber
                itemBinding.tvPaymentAmount.text = paymentBean.totalAmount
            }
        }
    }

Also, make sure you pass the root view to the parent class of Viewholder like this RecyclerView.ViewHolder(itemBinding.root) by accessing the passed binding class object.

Solution 2:

Attach the binding to the ViewHolder instead of the View

class CardViewHolder(val binding: CardBinding) : RecyclerView.ViewHolder(binding.root)

You pass the binding, the binding passes binding.root to RecyclerView.ViewHolder(binding.root)

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

Then access anywhere with:

holder.binding.title