Generic databinding adapter for items in Recyclerview

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>
    <androidx.constraintlayout.widget.ConstraintLayout
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
        <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/rv"
                android:layout_width="match_parent"
                android:layout_height="match_parent"/>
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

item_content.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>

    <data>
        <variable name="model" type="String"/>
    </data>
    <androidx.constraintlayout.widget.ConstraintLayout
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingStart="@dimen/margin_padding_32"
            android:paddingEnd="@dimen/margin_padding_0"
            android:background="@color/pale_grey"
            android:paddingTop="@dimen/margin_padding_12"
            android:paddingBottom="@dimen/margin_padding_12">

        <TextView android:id="@+id/content"
                  android:layout_width="match_parent"
                  tools:text="The Basics"
                  android:textAllCaps="true"
                  android:layout_height="wrap_content"
                  android:text="@{model}"/>

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

item_header.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>

    <data>
        <variable name="model" type="String"/>
    </data>
    <androidx.constraintlayout.widget.ConstraintLayout
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingStart="@dimen/margin_padding_32"
            android:paddingEnd="@dimen/margin_padding_0"
            android:background="@color/pale_grey"
            android:paddingTop="@dimen/margin_padding_12"
            android:paddingBottom="@dimen/margin_padding_12">

        <TextView android:id="@+id/desc"
                  android:layout_width="match_parent"
                  tools:text="The Basics"
                  android:textAllCaps="true"
                  android:layout_height="wrap_content"
                  android:text="@{model}"/>

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

items.kt

data class HeaderViewType(private val title: String?= null) : ViewType<String?> {

    override fun layoutId(): Int = R.layout.item_header

    override fun data(): String? = title
    
    override fun isUserInteractionEnabled() = false
}

data class RowViewType(private val content: String?= null) : ViewType<String?> {

    override fun layoutId(): Int = R.layout.item_header

    override fun data(): String? = content
}

SampleActivity.kt

import androidx.recyclerview.widget.RecyclerView

class SampleActivity: Activity(), OnItemActionListener {
  
   private val adapter by lazy { ViewTypeAdapter<ViewType<*>>(list = list, onItemActionListener = this) }
  
   //Prepare the list somehow, whether in ViewModel or presenter and then set it to adapter using setList
   private val list: List<ViewType<*>> by lazy {
      arrayListOf<>(HeaderViewType("Header"), 
                    RowViewType("content"),
                    RowViewType("content"),
                    RowViewType("content"))
   }
  
   override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val rv = findViewById(R.id.rv)
        rv.layoutManager = LinearLayoutManager(context, RecyclerView.VERTICAL, false)
        rv.adapter = adapter
   }
  
   override fun onItemClicked(position: Int) {
     //Do whatever you want to do with position
   }
  
}

ViewType.kt

import androidx.annotation.LayoutRes

/**
 *  Different view types for [RecyclerView]
 */
interface ViewType<out T> {

    @LayoutRes
    fun layoutId(): Int

    fun data(): T

    fun isUserInteractionEnabled() = true
}

ViewTypeAdapter.kt

import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.databinding.DataBindingUtil
import androidx.databinding.ViewDataBinding
import androidx.recyclerview.widget.RecyclerView
import *.BR

/**
 *  Adapter to populate the list of list
 */
class ViewTypeAdapter<E : ViewType<*>>(
    private var list: MutableList<E> = mutableListOf(),
    private val onItemActionListener: OnItemActionListener? = null
) : RecyclerView.Adapter<ViewTypeHolder>() {

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

        val binding: ViewDataBinding =
            DataBindingUtil.inflate(LayoutInflater.from(parent.context), viewType, parent, false)
        return ViewTypeHolder(binding, onItemActionListener)
    }

    override fun onBindViewHolder(holder: ViewTypeHolder, position: Int) {
        holder.bindItem(list[position])
    }

    override fun getItemViewType(position: Int): Int = list[position].layoutId()

    override fun getItemCount(): Int = list.size

    override fun setList(list: List<E>) {
        this.list.clear()
        this.list.addAll(list)
        notifyDataSetChanged()
    }

    fun insertElement(data: E, position: Int? = null) {
        if (position != null) {
            this.list.add(position, data)
            notifyItemInserted(position)
        } else {
            this.list.add(data)
            notifyItemInserted(this.list.size - 1)
        }
    }

    fun updateElement(data: E, position: Int) {
        this.list[position] = data
        notifyItemChanged(position)
    }
}

class ViewTypeHolder(private val binding: ViewDataBinding, private val onItemActionListener: OnItemActionListener?) :
    RecyclerView.ViewHolder(binding.root) {

    fun bindItem(item: ViewType<*>) {
        binding.setVariable(BR.model, item.data())
        if (item.isUserInteractionEnabled()) {
            binding.setVariable(BR.position, adapterPosition)
            binding.setVariable(BR.actionItemListener, onItemActionListener)
        }
        binding.executePendingBindings()
    }
}

interface OnItemActionListener {
    fun onItemClicked(position: Int)
}