Weird recyclerview refreshing issue

Question

I'm trying to create a file explorer synchronized with an FTP explorer, one of its features is to notify the new downloaded files. For that I store in Sharedpreferences the path of my file/folders and then I compare them with the new element stored in sharedprefs in my adapter, if my condition is true, I make a dot appear next to the folder/file name. It works really great except when I update my recyclerview as I switch back to the previous activity with notifyDataSetChanged() to update the file/folder if they have been read, or when I sort my list with notifyItemRangeChanged(). As you can see in my GIF, dots are appearing randomly everywhere in bad locations. I hope I explained well, how can I fix this issue? I'm really close, it's very frustrating.

Here's my onResume() :

    override fun onResume() {
    super.onResume()
    if(::recyclerViewRecents.isInitialized) {
        getRecentFiles()

        recyclerViewFolders.adapter?.notifyDataSetChanged()
        recyclerViewRecents.adapter?.notifyDataSetChanged()
    }
    }

And here my notifydatasetchange, I even try to clear the recycledViewPool but nothing change:

        recyclerViewFiles.adapter?.notifyItemRangeChanged(0,filesList.size)

Thanks

Edit:

Here's is my adapter code:

I check in onBindViewHolder if the file is registered to display the dot:

        val isRead: String? = prefNewFile.getString(currentFile.absolutePath, null)

    if (isRead!=null) {
        holder.fileIsRead.visibility = View.VISIBLE
        println(currentFile.name + " is unread")
    }

And here how I mark it as read:

private fun putAsRead(file: String) {
    println("$file read!")
    val editor: SharedPreferences.Editor = prefNewFile.edit()
    editor.remove(file)
    editor.apply()
    val folder = file.substring(0,file.lastIndexOf("/"))
    if(file.substring(file.lastIndexOf("/")) != "/CalvezDocs")
        putAsRead(folder)
}

Answer 1

The solution is just to add else option on Visibility. For example, holder.fileIsRead.isVisible = isRead == true or isRead != null It's short version of if (isRead != null ) View.VISIBLE else View.GONE

The reason of the problem is that RecyclerView reuses ViewHolders, when the adapter reuses a ViewHolder with holder.fileIsRead was set to View.VISIBLE previously, so you have extra item on your list.