Kotlin: Show AlertDialog when RecycleView item clicked

Question

Now I'm studying to show AlertDialog when RecyclerView item clicked. However, I don't know how to set the adapter for click listener. Could you give me a tip?

Firstly, I tried to put the AlertDialog in this Main Activity. Is this right position?

MainActivity

class MainActivity : AppCompatActivity() {

    private val foodList = listOf(
        FoodModel("Noodle", 2),
        FoodModel("Cake", 3),
        FoodModel("Pizza", 4),
        FoodModel("Stake", 5),
        FoodModel("Chicken", 4)
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        val adapter = FoodDataAdapter(foodList)
        adapter.notifyDataSetChanged()
        foodListView.adapter = adapter
        foodListView.layoutManager = LinearLayoutManager(this)

        fun onItemClick(item: FoodModel, position: Int) {
            val dialog = AlertDialog.Builder(this)
            dialog.setTitle("Item deletion")
            dialog.setMessage("Do you want to delete this item?")
            dialog.setPositiveButton("Yes", DialogInterface.OnClickListener { _, _ ->
            })
            dialog.setNegativeButton("No", DialogInterface.OnClickListener { _, _ ->
            })
            dialog.setNeutralButton("Cancel", DialogInterface.OnClickListener { _, _ ->
            })
            dialog.show()
        }
    }
}

This is the Adapter.

class FoodDataAdapter(val list: List<FoodModel>):RecyclerView.Adapter<FoodDataViewHolder>(){
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FoodDataViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.item_food,parent,false)
        return FoodDataViewHolder(view)
    }

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

    override fun onBindViewHolder(holder: FoodDataViewHolder, position: Int) {
        holder.containerView.nameText.text=list[position].name
        holder.containerView.priceText.text="${list[position].price}dollar"
    }
}

View holder

class FoodDataViewHolder(override val containerView: View) : RecyclerView.ViewHolder(containerView),LayoutContainer

Answer 1

I edited your code. MainActivity:

class MainActivity : AppCompatActivity(), FoodDataAdapter.OnItemClickListener {

var foodList = ArrayList<FoodModel>()
lateinit var adapter : FoodDataAdapter
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    foodlist.add(FoodModel("Noodle", 2))
    foodlist.add(FoodModel("Cake", 3))
    foodlist.add(FoodModel("Pizza", 4))
    foodlist.add(FoodModel("Stake", 5))
    foodlist.add(FoodModel("Chicken", 4))

    adapter = FoodDataAdapter(foodList, this)
    foodListView.adapter = adapter
    foodListView.layoutManager = LinearLayoutManager(this)

}

override fun alertDialog(position: Int) {
    val dialog = AlertDialog.Builder(this)
    dialog.setTitle("Item deletion")
    dialog.setMessage("Do you want to delete this item?")
    dialog.setPositiveButton("Yes", DialogInterface.OnClickListener { _, _ -> 
    adapter.removeItem(position)
    })
    dialog.setNegativeButton("No", DialogInterface.OnClickListener { _, _ ->
    })
    dialog.setNeutralButton("Cancel", DialogInterface.OnClickListener { _, _ ->
    })
    dialog.show()
}
}

FoodDataAdapter:

class FoodDataAdapter(var list: ArrayList<FoodModel>, var listener : FoodDataAdapter.OnItemClickListener):RecyclerView.Adapter<FoodDataAdapter.FoodDataViewHolder>(){

interface OnItemClickListener {
    fun alertDialog(position : Int)
}

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FoodDataViewHolder {
    val view = LayoutInflater.from(parent.context).inflate(R.layout.item_food,parent,false)
    return FoodDataViewHolder(view)
}

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

fun removeItem(position: Int) {
    list.removeAt(position)
    notifyItemRemoved(position)
}

override fun onBindViewHolder(holder: FoodDataViewHolder, position: Int) {
    holder.nameText.text=list[position].name
    holder.priceText.text="${list[position].price}dollar"
}

inner class FoodDataViewHolder(containerView: View) : RecyclerView.ViewHolder(containerView),
    View.OnClickListener {

    var nameText: TextView = containerView.findViewById(R.id.nameText)
    var priceText: TextView = containerView.findViewById(R.id.priceText)

    init {
        containerView.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        listener.alertDialog(adapterPosition)
    }
}
}