Select just one ImageView at a time inside RecyclerView Adapter

Question

I have a RecyclerView filled with different images, when the user click one of then i apply a border to highlight the image. Everything is working fine, however, the user can click multiple images and all of then get highlighted, i want to select only one at a time. I have search over multiples sites and posts however none of them have a solution that works for me. Here is an image:

I am using a ImageView click listener, not an ItemClickListener.

Here is the adapter code:

import android.content.Context
import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView

class AccountViewHolder(view: View) : RecyclerView.ViewHolder(view) {
    var accountImage: ImageView = 
        view.findViewById(R.id.account_image_placeholder)
}

class AddEditAccountAdapter(private var context: Context, private var 
    accountImages: ArrayList<String>) :
    RecyclerView.Adapter<AccountViewHolder>() {

       override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): 
AccountViewHolder {
    val imageItem = LayoutInflater.from(context).inflate(
        R.layout.account_image_item,
        parent, false
    )

    return AccountViewHolder(imageItem)
}

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

override fun onBindViewHolder(holder: AccountViewHolder, position: Int) {

    val accountImageId =
        context.getResources().getIdentifier(accountImages.get(position), "drawable", context.getPackageName())

    holder.accountImage.setImageResource(accountImageId)

    holder.accountImage.setOnClickListener {

        holder.accountImage.setBackgroundResource(R.drawable.image_highlight)
    }
}
}

Answer 1

you should have a global field to hold your selected position like below:

var selectedPos = -1 // hold selected position in your adapter
// in your bindView, because your view will be reused, you should always check the selected position to set the suitable background
holder.accountImage.setBackgroundResource(if(selectedPos == position) yourImageHightlight else yourNormalImage)

holder.accountImage.setOnClickListener {
    selectedPos = position
    notifyDataSetChanged()// or something like notifyItemChanged()...
}