Template for Android RecyclerView

TemplateAndroidRecyclerView.kt

data class SomeObject(val id: Int)

class SampleRecyclerViewAdapter(private val listener: SampleOnClickListener?) :
    RecyclerView.Adapter<RecyclerView.ViewHolder>() {

    private var items = mutableListOf<SomeObject>()

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder = when (viewType) {
        VIEW_TYPE_SAMPLE -> SampleViewHolder.create(LayoutInflater.from(parent.context), parent, listener)
        else -> throw IllegalArgumentException("$viewType is unexpected here.")
    }

    override fun getItemCount(): Int = items.size

    override
    fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) = when (holder) {
        is SampleViewHolder -> {
        }
        else -> {
        }
    }

    @Synchronized
    fun addAll(newList: List<SomeObject>) {
        synchronized(items) {
            val diffUtils = DiffUtil.calculateDiff(SampleDiffUtil(items, newList))
            items = newList.toMutableList()
            diffUtils.dispatchUpdatesTo(this)
        }
    }

    companion object {
        private const val VIEW_TYPE_SAMPLE = 1
    }
}

typealias SampleOnClickListener = (SomeObject?) -> Unit

class SampleViewHolder private constructor(itemView: View, listener: SampleOnClickListener?) :
    RecyclerView.ViewHolder(itemView) {

    fun bind(any: SomeObject) {
        // TODO do your job
    }

    companion object {
        private const val LAYOUT = R.layout.abc_action_menu_item_layout
        fun create(inflater: LayoutInflater, parent: ViewGroup?, listener: SampleOnClickListener?) =
            SampleViewHolder(inflater.inflate(LAYOUT, parent, false), listener)
    }
}

class SampleDiffUtil(
    private val oldList: List<SomeObject>,
    private val newList: List<SomeObject>
) : DiffUtil.Callback() {

    override fun getOldListSize(): Int = oldList.size

    override fun getNewListSize(): Int = newList.size

    override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean =
        //TODO ID除いたその他の値のequal比較をオブジェクトごとに比較する
        oldList[oldItemPosition].hashCode() == newList[newItemPosition].hashCode()

    override
    fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean =
        oldList[oldItemPosition].id == newList[newItemPosition].id
}