tonnylitao

data class Comment(
  ...
) : RecyclerItem {
 ...
}

data class ComplexModel(
  val model: SomeModel
  ...
) : RecyclerItem {

tonnylitao

class MainFragment: 
  Fragment(R.layout.fragment_main) {
    
    private val adapter by lazy {
      
      RecyclerAdapter(
        RecyclerItem.diffCallback<User>(),
        R.layout.list_item_user_placeholder
      ) { _, _, item ->
         

tonnylitao

data class User(
    ...
) : RecyclerItem {
    override val layoutId: Int
        get() = R.layout.list_item_user

    override val variableId: Int
        get() = BR.user

    override val dataToBind: Any

tonnylitao

override fun onBindViewHolder(
  holder: ViewHolder, 
  position: Int
){
 getItem(position)?.run(holder.binding::bind)
}

} //end of RecyclerAdapter

private fun ViewDataBinding.bind(

tonnylitao

inner class ViewHolder(
 val binding: ViewDataBinding
): RecyclerView.ViewHolder(binding.root)

tonnylitao

override fun getItemViewType(position: Int) 
 = requireNotNull(
  getItem(position)?.layoutId ?: placeholderId
 ){
  "item at $position is null"
 }

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

tonnylitao

class RecyclerAdapter<M : RecyclerItem>(

 diffCallback: DiffUtil.ItemCallback<M>,

 @LayoutRes val placeholderId: Int?,

 private val clickListener: Listener? = null
  
) : PagedListAdapter<M, ViewHolder<M>>
  (diffCallback) {

tonnylitao

import androidx.recyclerview.widget.DiffUtil

interface RecyclerItem {
 val layoutId: Int

 val variableId: Int
 val dataToBind: Any

 val id: Int

tonnylitao

class IntViewModelFactory(val application: Application, val int: Int) :
    ViewModelProvider.NewInstanceFactory() {

    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel?> create(modelClass: Class<T>) =
        IntViewModel(application, int) as T
}

class StringViewModelFactory(val application: Application, val string: String) :
    ViewModelProvider.NewInstanceFactory() {

tonnylitao

import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import kotlin.reflect.full.primaryConstructor

class AndroidViewModelFactory(private vararg val args: Any) :
    ViewModelProvider.NewInstanceFactory() {

    override fun <T : ViewModel> create(modelClass: Class<T>) =
        modelClass.kotlin.primaryConstructor?.call(*args)
            ?: throw IllegalArgumentException("$modelClass primaryConstructor is null")