Android ListAdapter适配Transaction与Bank两种数据模型时类型参数报错问题咨询

First, let's clarify why your initial approach failed: ListAdapter is designed to work with a single data type as its first generic parameter (the definition is ListAdapter<T, VH extends RecyclerView.ViewHolder>), so passing three types like ListAdapter<Transaction, Bank, RecyclerView.ViewHolder> will always throw a "requires 2 type arguments" error.

To handle both Transaction and Bank models in the same adapter, we'll use a sealed class to wrap both types into a unified list item, then adjust the adapter to work with this wrapper. Here's a step-by-step implementation:

Step 1: Create a Sealed Class for Unified List Items #

This class will act as a container for both your models, letting the adapter distinguish between them:

sealed class ListItem {
    data class TransactionItem(val transaction: Transaction) : ListItem()
    data class BankItem(val bank: Bank) : ListItem()
}

Step 2: Update the DiffUtil Callback #

We need a DiffUtil.ItemCallback that can compare our sealed class items:

class ListItemDiffCallback : DiffUtil.ItemCallback<ListItem>() {
    override fun areItemsTheSame(oldItem: ListItem, newItem: ListItem): Boolean {
        return when {
            oldItem is ListItem.TransactionItem && newItem is ListItem.TransactionItem -> 
                oldItem.transaction.transId == newItem.transaction.transId
            oldItem is ListItem.BankItem && newItem is ListItem.BankItem -> 
                oldItem.bank.id == newItem.bank.id // Replace with Bank's unique identifier
            else -> false
        }
    }

    override fun areContentsTheSame(oldItem: ListItem, newItem: ListItem): Boolean {
        return oldItem == newItem
    }
}

Step 3: Rewrite the Adapter Class #

Modify your TransactionHistory adapter to use ListItem as the data type, and add logic to handle both item types:

class TransactionHistory() : ListAdapter<ListItem, RecyclerView.ViewHolder>(ListItemDiffCallback()) {
    private val ITEM_VIEW_TYPE_TRANSACTION = 1
    private val ITEM_VIEW_TYPE_BANK = 2
    private val ITEM_VIEW_TYPE_EMPTY = 0

    override fun getItemViewType(position: Int): Int {
        return if (itemCount == 0) {
            ITEM_VIEW_TYPE_EMPTY
        } else {
            when (getItem(position)) {
                is ListItem.TransactionItem -> ITEM_VIEW_TYPE_TRANSACTION
                is ListItem.BankItem -> ITEM_VIEW_TYPE_BANK
            }
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        return when (viewType) {
            ITEM_VIEW_TYPE_TRANSACTION -> TransactionViewHolder.from(parent)
            ITEM_VIEW_TYPE_BANK -> BankViewHolder.from(parent)
            ITEM_VIEW_TYPE_EMPTY -> EmptyViewHolder.from(parent)
            else -> throw ClassCastException("Unknown viewType $viewType")
        }
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
        val item = getItem(position)
        when (holder) {
            is TransactionViewHolder -> {
                val transactionItem = item as ListItem.TransactionItem
                holder.bind(transactionItem.transaction, clickListener)
            }
            is BankViewHolder -> {
                val bankItem = item as ListItem.BankItem
                holder.bind(bankItem.bank, clickListener)
            }
            is EmptyViewHolder -> holder.bind()
        }
    }

    lateinit var clickListener: AdapterListener2

    fun setOnclickListener(listener: AdapterListener2) {
        clickListener = listener
    }

    // Existing Transaction ViewHolder (renamed for clarity)
    class TransactionViewHolder private constructor(val binding: ItemUserTransactionListBinding) : RecyclerView.ViewHolder(binding.root) {
        fun bind(item: Transaction, adapterListener2: AdapterListener2) {
            binding.transaction = item
            binding.clickListener = adapterListener2
            binding.executePendingBindings()
            
            binding.transactionStatus.text = when(item.type) {
                "payPayment" -> "برداخت قسط"
                "decrease" -> "برداشت"
                "increase" -> "واریز"
                else -> ""
            }
            
            binding.amount.text = item.decrease ?: item.increase
        }

        companion object {
            fun from(parent: ViewGroup): TransactionViewHolder {
                val inflater = LayoutInflater.from(parent.context)
                val binding = ItemUserTransactionListBinding.inflate(inflater, parent, false)
                return TransactionViewHolder(binding)
            }
        }
    }

    // New ViewHolder for Bank items
    class BankViewHolder private constructor(val binding: ItemBankInfoBinding) : RecyclerView.ViewHolder(binding.root) {
        fun bind(item: Bank, adapterListener2: AdapterListener2) {
            binding.bankInfo = item
            binding.clickListener = adapterListener2
            binding.executePendingBindings()
            // Add any Bank-specific binding logic here
        }

        companion object {
            fun from(parent: ViewGroup): BankViewHolder {
                val inflater = LayoutInflater.from(parent.context)
                val binding = ItemBankInfoBinding.inflate(inflater, parent, false)
                return BankViewHolder(binding)
            }
        }
    }

    // Empty ViewHolder remains unchanged
    class EmptyViewHolder private constructor(val binding: ItemUserTransactionListBinding) : RecyclerView.ViewHolder(binding.root) {
        fun bind() {
            binding.executePendingBindings()
        }

        companion object {
            fun from(parent: ViewGroup): EmptyViewHolder {
                val inflater = LayoutInflater.from(parent.context)
                val binding = ItemUserTransactionListBinding.inflate(inflater, parent, false)
                return EmptyViewHolder(binding)
            }
        }
    }
}

Step 4: Combine and Submit Data #

To use the adapter, merge your Transaction and Bank lists into a single list of ListItem (this is what the "join operation" suggestion refers to):

// Fetch your data sources
val transactions: List<Transaction> = getTransactions()
val banks: List<Bank> = getBanks()

// Combine into a unified list
val combinedList = transactions.map { ListItem.TransactionItem(it) } + banks.map { ListItem.BankItem(it) }

// Submit to adapter
transactionHistoryAdapter.submitList(combinedList)

Notes: #

• If Transaction and Bank can share the same layout, you can skip creating a separate BankViewHolder and modify the existing TransactionViewHolder to handle both item types, but separate ViewHolders keep your code cleaner.
• Update AdapterListener2 if you need different click logic for Bank items (e.g., add a bank-specific click handler).

内容的提问来源于stack exchange，提问作者AmirHossein