SimpleListBindingAdapter.kt

/**
 * Generic Adapter for a list of ITEMS and a BINDING class
 */
class SimpleListBindingAdapter<in ITEM, BINDING : ViewDataBinding> :
    RecyclerView.Adapter<SimpleListBindingAdapter<ITEM, BINDING>.BindingHolder> {

    private var items = listOf<ITEM>()
    @LayoutRes
    private var layoutRes: Int = 0

    var listener: OnItemClickListener<BINDING>? = null
        set(value) {
            field = value
            notifyDataSetChanged()
        }

    constructor(layoutRes: Int) {
        this.layoutRes = layoutRes
    }

    constructor(layoutRes: Int, items: List<ITEM>?) {
        this.items = items ?: listOf()
        this.layoutRes = layoutRes
    }

    init {
        setHasStableIds(true)
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BindingHolder {

        val binding = DataBindingUtil.inflate<BINDING>(
            LayoutInflater.from(parent.context),
            layoutRes,
            parent,
            false
        )

        if (binding == null) {
            Timber.e("Layout resource given is not wrapped with <layout> tag")
        }
        return BindingHolder(binding!!)
    }

    override fun onBindViewHolder(holder: BindingHolder, position: Int) {
        holder.bind()
    }

    override fun getItemCount(): Int = items.size

    override fun getItemId(position: Int): Long {
        return items[position].hashCode().toLong()
    }

    fun swapList(items: List<ITEM>) {
        if (this.items != items) {
            this.items = items
            notifyDataSetChanged()
        }
    }

    inner class BindingHolder(private val binding: BINDING) : RecyclerView.ViewHolder(binding.root),
        View.OnClickListener {

        init {
            binding.root.setOnClickListener(this)
        }

        fun bind() {
            binding.setVariable(BR.viewModel, items[layoutPosition])
            binding.executePendingBindings()
        }

        override fun onClick(view: View) {
            listener?.onItemClick(binding, adapterPosition)
        }
    }

    interface OnItemClickListener<BINDING : ViewDataBinding> {
        fun onItemClick(binding: BINDING, position: Int)
    }
}