RecylerView with databinding

 It is very easy to create RecyclerView with Databinding.

Step 1: - First you have to Enable DataBinding by giving following code in gradle file :- 

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.3"

    defaultConfig {
        applicationId "com.blizle"
        minSdkVersion 21
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    dataBinding {
        enabled = true
    }

    lintOptions {
        checkReleaseBuilds false
// Or, if you prefer, you can continue to check for errors in release builds,
// but continue the build even when errors are found:
        abortOnError false
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

To enable data-binding you have to specify

 dataBinding {
        enabled = true
    }

Then add some more libraries for data-binding, as followiing.

def life_versions = "1.1.1"
implementation "android.arch.lifecycle:extensions:$life_versions"
annotationProcessor "android.arch.lifecycle:compiler:$life_versions"
implementation 'com.android.support:multidex:1.0.3'
implementation 'com.android.databinding:compiler:1.0-rc0'
implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'

Now all set for data-binding.

Step :- 

Add Library for ReceyclerView and add tag RecyclerView in XML file :- 

<androidx.recyclerview.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    recyclerAdapter="@{mainViewModel.adapter}"
    tools:listitem="@layout/adapter_layout"
    app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

After that create Recycler Adapter and its ViewModel all the click that you want to 
perform then you can manage those clicks in adapter's ViewModel.

RecyclerView Adapter :-

class Adapter(var context: Context) : RecyclerView.Adapter<Adapter.ViewHolder>() {

    var list: ArrayList<MainVIewModel.ListModel> = ArrayList()

    fun update(ls:ArrayList<MainVIewModel.ListModel>) {
        list.clear()
        list.addAll(ls)
        notifyDataSetChanged()
    }

    inner class ViewHolder(var adapterLayoutBinding: AdapterLayoutBinding) :
        RecyclerView.ViewHolder(adapterLayoutBinding.root) {

        fun setData(listModel: MainVIewModel.ListModel) {
            try {
                val adapterViewModel = AdapterVM(context, listModel)
                adapterLayoutBinding.adapterVm = adapterViewModel
                adapterLayoutBinding.executePendingBindings()
            }catch (e:Exception) {
                e.printStackTrace()
            }
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val adapterLayoutBinding = AdapterLayoutBinding.inflate(LayoutInflater.from(context), parent, false)
        return ViewHolder(adapterLayoutBinding)
    }

    override fun getItemCount(): Int {
       return list.size
    }

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

And create Another class for recycler adapter's ViewModel as Following :- 
class AdapterVM(var context: Context, var listModel: MainVIewModel.ListModel) 

Now Create Binding Adapter to set Recycler Adapter :-

if there is any problem or error with @BindingAdapter(value = ["recyclerAdapter"], requireAll = false)
this line then make sure you have declare 'id kotlin-lapt'  in your gradle file

import android.graphics.drawable.Drawable
import android.widget.ImageView
import androidx.databinding.BindingAdapter
import androidx.recyclerview.widget.RecyclerView

object BindingAdapter {

    @BindingAdapter(value = ["recyclerAdapter"], requireAll = false)
    @JvmStatic
    fun recyclerAdapter(recyclerView: RecyclerView, adapter: RecyclerView.Adapter<*>) {
        recyclerView.adapter = adapter
    }

    @BindingAdapter(value = ["setPhoto"], requireAll = false)
    @JvmStatic
    fun setPhoto(imageView: ImageView, drawable: Int) {
        imageView.setBackgroundResource(drawable)
    }
}

And you also have to create ViewModel class for main class and factory class to pass parameters.

 MainActivity :-

class MainActivity : AppCompatActivity() {

    var activityMainBinding: ActivityMainBinding?=null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
         activityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
        val mainFactory = MainFactory(this)
        val activityViewModel = ViewModelProvider(this, mainFactory).get(MainVIewModel::class.java)
        activityMainBinding!!.mainViewModel= activityViewModel
    }
}

Create ViewModel for main class:-

class MainVIewModel(var context: Context) : ViewModel() {

    var list: ArrayList<ListModel> = ArrayList()
    var adapter: Adapter?=null


    init {
        list.add(ListModel(R.drawable.car1, "Car 1"))
        list.add(ListModel(R.drawable.car2, "Car 2"))
        list.add(ListModel(R.drawable.car3, "Car 3"))
        list.add(ListModel(R.drawable.cars4, "Car 4"))
        list.add(ListModel(R.drawable.cars5, "Car 5"))
        adapter = Adapter(context)
        adapter!!.update(list)
    }


    data class ListModel(
        var image: Int,
        var title: String = ""
    )
}

Create Factory for main class and viewmodel :-

class MainFactory(var context: Context) : ViewModelProvider.Factory {
    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
        if (modelClass.isAssignableFrom(MainVIewModel::class.java)) {
            return MainVIewModel(context) as T
        }
        throw IllegalArgumentException("unKnow Error")
    }
}


Now all set you have Create recycler Adapter with databinding.