RecycerView.Adapter。重写的方法onCreateViewHolder参数在viewType参数中始终为零

Question

我想使RecycerView具有多种视图类型。如本主题：链接。

我知道这种方法的关键是方法getItemViewType（position：Int）：Int{}。

fun getItemViewType(position: Int): Int { return 100 }

    class OrdersAdapter(val iAbsListFragment: IAbsListFragment,
                    val listItemsLD: LiveData<Result<List<Order>>>
) : RecyclerView.Adapter<OrderViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OrderViewHolder {
        viewType
        return OrderViewHolder(
            LayoutInflater.from(parent.context)
                .inflate(R.layout.card_order, parent, false), iAbsListFragment
        )
    }

    override fun getItemViewType(position: Int): Int { return 100 }

    override fun getItemCount(): Int {
        return if (listItemsLD.value is Result.Success) {
            (listItemsLD.value as Result.Success<List<Order>>).data.size
        } else {
            0
        }
    }

    override fun onBindViewHolder(holder: OrderViewHolder, position: Int) {
        if (listItemsLD.value is Result.Success) {
            val order = (listItemsLD.value as Result.Success<List<Order>>).data[position]
            holder.bindTo(order)
        }
    }
}

Answer 1

别问我为什么。onCreateViewHolder必须返回RecycerView.Viewholder但不能返回RecycerView.Viewholder实现，则viewType参数将从getItemViewType（位置：Int）获得viewType

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OrderViewHolder //wrong, viewType always zero

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OrderViewHolder //work well, viewType from "override fun getItemViewType"