DiffUtils kotlin extension

MyRecyclerViewAdapter.kt

class DeliveryWindowsAdapter : RecyclerView.Adapter<DeliveryWindowsAdapter.ViewHolder>() {

    var items: List<DeliveryWindowUiModel> by Delegates.observable(emptyList()) { _, oldList, newList ->
        autoNotify(oldList, newList) { o, n -> o.id == n.id }
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val deliveryWindow = items[position]
        holder.title.text = deliveryWindow.title
        holder.price.text = deliveryWindow.friendlyPrice
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val itemView = LayoutInflater.from(parent.context).inflate(R.layout.book_delivery_item_cell, parent, false)
        return ViewHolder(itemView)
    }

    override fun getItemCount(): Int = items.size

    inner class ViewHolder(v: View) : RecyclerView.ViewHolder(v) {
        val title: TextView = v.titleTextView
        val price: TextView = v.priceTextView
    }
}

RecyclerViewExtensions.kt

package com.example

import android.support.v7.util.DiffUtil
import android.support.v7.widget.RecyclerView

fun <T> RecyclerView.Adapter<*>.autoNotify(oldList: List<T>, newList: List<T>, compare: (T, T) -> Boolean) {

    val diff = DiffUtil.calculateDiff(object : DiffUtil.Callback() {
        override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
            return compare(oldList[oldItemPosition], newList[newItemPosition])
        }

        override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
            return oldList[oldItemPosition] == newList[newItemPosition]
        }

        override fun getOldListSize() = oldList.size
        override fun getNewListSize() = newList.size
    })
    diff.dispatchUpdatesTo(this)
}

YourActivity.kt

fun updateList(list: List<DeliveryUiModel>) {
  theAdapter.items = list
}