Why my diffutils dont update my position in background - xamarin.forms

Question

I'm using DiffUtils to update my Recyclerview.
Visually works but clicking an item returns it to me a position that does not match the item I clicked
I used NotifyDataChange that was able to solve the position problem. But visually, the last item is misconfigured.
I try to use NotifyDataChange that was able to solve the position problem. But visually, the last item is misconfigured.
My adapter:
class AdapterUser : RecyclerView.Adapter
{
//Global Var
public event EventHandler<int> ItemClick;
public List<Class.Result> ClassUser;
public Android.Content.Context context;
public class UserViewHolder : RecyclerView.ViewHolder
{
public static TextView txtName { get; set; }
public static TextView txtEspecialidade { get; set; }
public static CircleImageView Imagem { get; set; }
public static Bitmap bitmap { get; set; }
public static CircleImageView status { get; set; }
public static Button button { get; set; }
public UserViewHolder(View itemview, Action<int> listener) : base(itemview)
{
UserViewHolder.txtName = itemview.FindViewById<TextView>(Resource.Id.nameUser);
UserViewHolder.txtEspecialidade = itemview.FindViewById<TextView>(Resource.Id.speciality);
UserViewHolder.Imagem = itemview.FindViewById<CircleImageView>(Resource.Id.avatarUser);
UserViewHolder.status = itemview.FindViewById<CircleImageView>(Resource.Id.status);
UserViewHolder.button = itemview.FindViewById<Button>(Resource.Id.BtCriar);
}
}
public AdapterUser(List<Class.Result> user)
{
ClassUser = user;
}
public override int ItemCount
{
get { return ClassUser.Count(); }
}
public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
{
//Method to transform the uri to bitmap
async Task MyMethodAsync()
{
// Do asynchronous work.
UserViewHolder.Imagem.SetImageBitmap(await Droid.Class.Functions.GetImageBitmapFromUrlAsync(ClassUser[position].PhotoUri));
};
UserViewHolder userHolder = holder as UserViewHolder;
if (ClassUser[position].PhotoUri != null)
{
MyMethodAsync();
}
else
{
UserViewHolder.Imagem.SetImageResource(Resource.Drawable.avatar);
}
if (ClassUser[position].IsOnline != true)
{
UserViewHolder.status.Visibility = ViewStates.Invisible;
}
else
{
UserViewHolder.status.Visibility = ViewStates.Visible;
}
UserViewHolder.txtName.Text = ClassUser[position].Name;
UserViewHolder.txtEspecialidade.Text = ClassUser[position].Specialty;
UserViewHolder.button.Click += (sender, args) =>
{
Toast.MakeText(context, ClassUser[position].Name, ToastLength.Short).Show();
Console.WriteLine(ClassUser[position].Name);
};
}
public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
{
View itemView = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.ResultUser, parent, false);
UserViewHolder vh = new UserViewHolder(itemView, OnClick);
context = parent.Context;
return vh;
}
private void OnClick(int obj)
{
}
public void Update(List<Class.Result> oldList, List<Class.Result> newList)
{
// Set detectMoves to true for smoother animations
MyDiffCallback callback = new MyDiffCallback(oldList, newList);
DiffUtil.DiffResult result = DiffUtil.CalculateDiff(callback);
this.ClassUser.Clear();
this.ClassUser.AddRange(newList);
// Despatch the updates to your RecyclerAdapter
result.DispatchUpdatesTo(this);
}
My DiffUtills:
class MyDiffCallback : DiffUtil.Callback
{
List<Class.Result> newList;
List<Class.Result> oldList;
public MyDiffCallback(List<Class.Result> oldList, List<Class.Result> newList)
{
this.oldList = oldList;
this.newList = newList;
}
public override int NewListSize => newList.Count;
public override int OldListSize => oldList.Count;
public override bool AreContentsTheSame(int oldItemPosition, int newItemPosition)
{
return oldList[oldItemPosition].IsOnline == newList[newItemPosition].IsOnline;
}
public override bool AreItemsTheSame(int oldItemPosition, int newItemPosition)
{
return oldList[oldItemPosition].RowKey == newList[newItemPosition].RowKey;
}
public override Java.Lang.Object GetChangePayload(int oldItemPosition, int newItemPosition)
{
return base.GetChangePayload(oldItemPosition, newItemPosition);
}
}
My activity:
ClassUtilizador = Data.Result.ToString();
Class.ClassUtilizador classUser = JsonConvert.DeserializeObject<Class.ClassUtilizador>(Data.Result.ToString());
//Call the function to update item
adapter.Update(classUserOld.Result, classUser.Result);
//Clean class and put the new data
classUserOld = new Class.ClassUtilizador();
classUserOld = classUser;
Update items, remove, add ou move items. Depending of my request.

Answer 1

You should call:
holder.bindingAdapterPosition

Answer 2

clicking an item returns it to me a position that does not match the
item I clicked
UserViewHolder.button.Click += (sender, args) =>
{
Toast.MakeText(context, ClassUser[position].Name, ToastLength.Short).Show();
Console.WriteLine(ClassUser[position].Name);
};
change to :
UserViewHolder.button.Tag = position;
UserViewHolder.button.SetOnClickListener(this);
then let your adapter extends View.IOnClickListener
class AdapterUser : RecyclerView.Adapter,View.IOnClickListener
public void OnClick(View v)
{
//here you could get the correct position
Toast.MakeText(context, v.Tag.ToString(), ToastLength.Short).Show();
}
if it doesn't update your Recyclerview, you could add the method in your adapter:
public void setData(List<Class.Result> newList)
{
this.ClassUser= new List<Class.Result>(newList);
}
in your update method :
public void Update(List<Class.Result> oldList, List<Class.Result> newList)
{
// Set detectMoves to true for smoother animations
MyDiffCallback callback = new MyDiffCallback(oldList, newList);
DiffUtil.DiffResult result = DiffUtil.CalculateDiff(callback);
this.ClassUser.Clear();
this.ClassUser.AddRange(newList);
setData(this.ClassUser);
// Despatch the updates to your RecyclerAdapter
result.DispatchUpdatesTo(this);
}