Android Kotlin - Recycler View DiffUtil.ItemCallback

DiffUtilItemListRecyclerViewAdapter.kt

import android.view.LayoutInflater
import android.view.ViewGroup
import android.widget.ImageView
import androidx.core.content.ContextCompat
import androidx.recyclerview.widget.AsyncListDiffer
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.RecyclerView

class QuestionBankListRecyclerViewAdapter(
    private val onClickItem: ((questionBank: QuestionBank, position: Int) -> Unit)? = null
) :
    RecyclerView.Adapter<QuestionBankListRecyclerViewAdapter.ViewBinder>() {
    private val TAG by lazy { this::class.simpleName }

    private val differCallback = object : DiffUtil.ItemCallback<QuestionBank>() {
        override fun areItemsTheSame(oldItem: QuestionBank, newItem: QuestionBank): Boolean {
            return oldItem.id == newItem.id
        }

        override fun areContentsTheSame(oldItem: QuestionBank, newItem: QuestionBank): Boolean {
            return oldItem == newItem
        }
    }

    val differ = AsyncListDiffer(this, differCallback)

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewBinder {
        val binding =
            RowQuestionBankBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return ViewBinder(binding)
    }

    override fun onBindViewHolder(holder: ViewBinder, position: Int) {
        val questionBank = differ.currentList[position]

        holder.viewBinder.questionBank = questionBank

        holder.viewBinder.executePendingBindings()
    }

    override fun getItemCount(): Int = differ.currentList.size

    // color list for random background
    private fun getColorList() = listOf(
        R.color.orange_550,
        R.color.green_550,
        R.color.blue_550,
        R.color.brown_550,
        R.color.purple_550,
        R.color.awesome_red_550
    )

    // set thumbnail color filter
    private fun setThumbnailColorFilter(imageView: ImageView) {
        try {
            imageView.imageTintList =
                ContextCompat.getColorStateList(
                    imageView.context,
                    getColorList().random()
                )
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

    inner class ViewBinder(val viewBinder: RowQuestionBankBinding) :
        RecyclerView.ViewHolder(viewBinder.root) {

        init {
            onItemClickHandler()

            setThumbnailColorFilter(viewBinder.thumbnailIv)
        }

        private fun onItemClickHandler() {
            onClickItem ?: return

            viewBinder.root.setOnClickListener {
                val position = absoluteAdapterPosition

                if (position == RecyclerView.NO_POSITION) return@setOnClickListener

                val questionBank = differ.currentList[position]

                onClickItem.invoke(questionBank, position)
            }
        }
    }
}