Android RecyclerView: Async DiffUtill

AsyncDiffUtilExample.kt

@Singleton
class PatientUserChatAdapter @Inject constructor() :
    RecyclerView.Adapter<PatientUserChatViewHolder>() {
    //
    private var dataSet: MutableList<UserChatDataModel> = mutableListOf()
    private var callback: PatientUserChatSelectionCallback? = null


    //Register for action callback
    fun setActionCallback(callback: PatientUserChatSelectionCallback? = null) {
        this.callback = callback
    }

    /**
     * Set list of [UserChatDataModel] to the adapter to show on the UI.
     *
     * Do all the logical operation under a [Dispatchers.Default] scope.
     *
     * Dispatch the update under a [Dispatchers.Main] scope.
     *
     * @param list, [MutableList<UserChatDataModel>]
     */
    fun setDataSet(list: MutableList<UserChatDataModel>) {
        CoroutineScope(Dispatchers.Default).launch {
            Logger.d("PatientUserChatAdapter : Working on Background")
            val callback = DiffUtil.calculateDiff(DiffCallback(list, dataSet))
            this@PatientUserChatAdapter.dataSet.clear()
            this@PatientUserChatAdapter.dataSet.addAll(list)
            withContext(Dispatchers.Main) {
                callback.dispatchUpdatesTo(this@PatientUserChatAdapter)
                Logger.d("PatientUserChatAdapter : Updating on Foreground")
            }
        }
    }


    //Clear the whole data set
    fun onDestroy() {
        setDataSet(mutableListOf())
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PatientUserChatViewHolder =
        PatientUserChatViewHolder(
            DataBindingUtil.inflate(
                LayoutInflater.from(parent.context),
                R.layout.content_item_patient_user_chat,
                parent,
                false
            )
        )

    override fun onBindViewHolder(holder: PatientUserChatViewHolder, position: Int) {
        callback?.let {
            holder.bindView(position, dataSet, it)
        }
    }

    override fun getItemCount(): Int = dataSet.size

    //DiffUtil callback
    private inner class DiffCallback(
        private val newList: MutableList<UserChatDataModel>,
        private val oldList: MutableList<UserChatDataModel>
    ) : DiffUtil.Callback() {

        override fun getOldListSize(): Int {
            return oldList.size
        }

        override fun getNewListSize(): Int {
            return newList.size
        }

        override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
            return newList[newItemPosition] == oldList[oldItemPosition]
        }

        override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
            return newList[newItemPosition] == oldList[oldItemPosition]
        }

    }
}


//View Holder Class
class PatientUserChatViewHolder(private val binding: ContentItemPatientUserChatBinding) :
    RecyclerView.ViewHolder(binding.root) {
    fun bindView(
        position: Int,
        list: MutableList<UserChatDataModel>,
        callback: PatientUserChatSelectionCallback
    ) {
        binding.model = list[position]
        binding.callback = callback
        binding.executePendingBindings()
    }
}

//XML Reference
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>

        <variable
            name="model"
            type=".UserChatDataModel" />

        <variable
            name="callback"
            type=".PatientUserChatSelectionCallback" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <androidx.cardview.widget.CardView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginTop="8dp"
            android:layout_marginEnd="16dp"
            android:layout_marginBottom="8dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">

            <androidx.constraintlayout.widget.ConstraintLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <GlideImageView
                    android:id="@+id/glideImageView"
                    android:layout_width="70dp"
                    android:layout_height="70dp"
                    android:layout_marginStart="16dp"
                    android:layout_marginTop="8dp"
                    android:layout_marginBottom="8dp"
                    app:layout_constraintBottom_toBottomOf="parent"
                    app:layout_constraintStart_toStartOf="parent"
                    app:layout_constraintTop_toTopOf="parent"
                    app:setImageUrlCircle="@{model.creator_avatar}"
                    app:srcCompat="@drawable/ic_profile_picture" />

                <ImageButton
                    android:id="@+id/glideImageView2"
                    android:layout_width="50dp"
                    android:layout_height="50dp"
                    android:layout_marginEnd="8dp"
                    android:background="?actionBarItemBackground"
                    android:onClick="@{() -> callback.onSelection(model)}"
                    app:layout_constraintBottom_toBottomOf="parent"
                    app:layout_constraintEnd_toEndOf="parent"
                    app:layout_constraintTop_toTopOf="parent"
                    app:srcCompat="@drawable/ic_baseline_keyboard_arrow_right_24" />

                <TextView
                    android:id="@+id/textView57"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="8dp"
                    android:ellipsize="marquee"
                    android:singleLine="true"
                    android:text="@{model.creator_displayname}"
                    android:textSize="16sp"
                    android:textStyle="bold"
                    app:layout_constraintEnd_toStartOf="@+id/glideImageView2"
                    app:layout_constraintStart_toEndOf="@+id/glideImageView"
                    app:layout_constraintTop_toTopOf="@+id/glideImageView"
                    tools:text="TextView" />

                <TextView
                    android:id="@+id/textView58"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="8dp"
                    android:layout_marginTop="8dp"
                    android:ellipsize="end"
                    android:maxLines="2"
                    android:text="@{model.lastMessageSent}"
                    app:layout_constraintEnd_toStartOf="@+id/glideImageView2"
                    app:layout_constraintStart_toEndOf="@+id/glideImageView"
                    app:layout_constraintTop_toBottomOf="@+id/textView57"
                    tools:text="TextView" />
            </androidx.constraintlayout.widget.ConstraintLayout>
        </androidx.cardview.widget.CardView>
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>