IssueTracker

Component used: ConcatAdapter

Version used: 1.2.0

Devices/Android versions reproduced on: any

The case is about two methods onViewRecycled and onFailedToRecycleView in ConcatAdapter. If you see the documentation of the base recycler view adapter it said that I can get a view holder position before it will be recycled by using ViewHolder#getBindingAdapterPosition() inside those two methods. But now comes ConcatAdapter who intercept those calls and execute its own code before it re-route them to nested adapters. The concat adapter executes the line which is removes viewHolder from mBinderLookup.

Concat Adapter triggers ConcatAdapterController.onViewRecycled:

public void onViewRecycled(ViewHolder holder) {
        NestedAdapterWrapper wrapper = mBinderLookup.remove(holder);
        if (wrapper == null) {
            throw new IllegalStateException("Cannot find wrapper for " + holder
                    + ", seems like it is not bound by this adapter: " + this);
        }
        wrapper.adapter.onViewRecycled(holder);
    }

The problem then comes out in nested adapter when I'm trying to get a view type of the view holder which is about to recycle:

override fun onViewRecycled(holder: RecyclerView.ViewHolder) {
    // delegatesManager will decide to which delegate to send onViewRecycled event using view type
    // but for Concat adapter holder.itemViewType will give me global view type which is useless in isolation mode
    delegatesManager.onViewRecycled(holder, getItemViewType(holder.bindingAdapterPosition))
  }

I use holder.getBindingAdapterPosition() and receive NO_POSITION, of course. Because the Concat Adapter throws my call through ConcatAdapterController again by triggering getLocalAdapterPosition:

public int getLocalAdapterPosition(
            Adapter<? extends ViewHolder> adapter,
            ViewHolder viewHolder,
            int globalPosition
    ) {
        NestedAdapterWrapper wrapper = mBinderLookup.get(viewHolder);
        if (wrapper == null) {
            return NO_POSITION;
        }
        int itemsBefore = countItemsBefore(wrapper);
        // local position is globalPosition - itemsBefore
        int localPosition = globalPosition - itemsBefore;
        // Early error detection:
        int itemCount = wrapper.adapter.getItemCount();
        if (localPosition < 0 || localPosition >= itemCount) {
            throw new IllegalStateException("Detected inconsistent adapter updates. The"
                    + " local position of the view holder maps to " + localPosition + " which"
                    + " is out of bounds for the adapter with size "
                    + itemCount + "."
                    + "Make sure to immediately call notify methods in your adapter when you "
                    + "change the backing data"
                    + "viewHolder:" + viewHolder
                    + "adapter:" + adapter);
        }
        return wrapper.adapter.findRelativeAdapterPositionIn(adapter, viewHolder, localPosition);
    }

This method using mBinderLookup to search for the NestedAdapterWrapper for this view holder (mBinderLookup.get(viewHolder)), but the thing is that it is already gone, it was removed a moment ago in ConcatAdapterController.onViewRecycled. So now I do not see a possibility to get local view type using just a view holder in my nested adapter onViewRecycled method. And I can't use global view type from the view holder itself, because I'm using isolateViewTypes = true.

Even though the current implementation does not match the documentation of recycler view, I don't see how to use multiple view types for the nested adapter in isolation mode.