How to use ViewBinding in a RecyclerView.Adapter?

Question

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)         // ...     } 

Answer 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.

Answer 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