giji.kt

class MainActivity : AppCompatActivity() {
    lateinit var adapter: RecyclerView.Adapter<RecyclerView.ViewHolder>
    var vmList = arrayListOf<MySweetViewModelable>()
    override fun onCreate(savedInstanceState: Bundle?) {
        // Title
        vmList.add(TitleViewModel("Hello, Ebisu!"))
// ...
        adapter = MySweetAdapter(vmList)
        my_sweet_recycler_view.adapter = adapter
    }
}
interface MySweetViewModelable {}
class TitleViewModel(val text: String): MySweetViewModelable
// ...
class MySweetAdapter(val vmList: List<MySweetViewModelable>) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
    // ...
    class TitleViewHolder(val binding: TitleBinding) : RecyclerView.ViewHolder(binding.root) {
        fun bind(vm: TitleViewModel) {
            binding.vm = vm
        }
    }
// x2
    override fun onBindViewHolder(holder: RecyclerView.ViewHolder?, position: Int) {
        when (holder!!.itemViewType) {
            ViewType.TITLE.type -> {
                println("onBindViewHolder: TITLE")
                (holder as? TitleViewHolder)?.bind(vmList[position] as TitleViewModel)
            }
            ViewType.FEED.type -> { // ... }
            ViewType.FOOTER.type -> { // ... }
        }
    }
    override fun getItemCount(): Int = vmList.size
    override fun getItemViewType(position: Int): Int {
        return when (position) {
            0 -> ViewType.TITLE.type
            in 1..vmList.size - 2 -> ViewType.FEED.type
            vmList.size - 1 -> ViewType.FOOTER.type
            else -> ViewType.FEED.type
        }
    }
    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): RecyclerView.ViewHolder {
        return when (viewType) {
            ViewType.TITLE.type -> TitleViewHolder(TitleBinding.inflate(LayoutInflater.from(parent!!.context), parent, false))
            ViewType.FEED.type -> FeedViewHolder(FeedBinding.inflate(LayoutInflater.from(parent!!.context), parent, false))
            ViewType.FOOTER.type -> FooterViewHolder(FooterBinding.inflate(LayoutInflater.from(parent!!.context), parent, false))
        }
    }
}