Strange drag&drop behavior using ItemTouchHelper and RecyclerView. How to fix?

Question

Java

I'm trying to use a RecyclerView with a very handy ItemTouchHelper for my purposes.
All I want is simple "drag & drop" and "swipe-to-dismiss" scripts.
Swipe works correctly, elements are removed correctly in the adapter, the animation also corresponds to what is happening, but “drag & drop” works very strangely. After a long click, the element does not start moving, although the selection is triggered, and the onItemMove method is called in the adapter.
Here's some weird behavior in my RecyclerView

And here's what I'm trying to achieve.

Here's the presenter code, onSelectedChanged and clearView , just to show the selection of items.

addedCitiesRecycler.setLayoutManager(llmAddedCities);

        adapterAddedCities = new AdapterAddedCities();

       
        ItemTouchHelper.SimpleCallback callback = new ItemTouchHelper.SimpleCallback(ItemTouchHelper.UP | ItemTouchHelper.DOWN, ItemTouchHelper.START | ItemTouchHelper.END) {
            @Override
            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
                adapterAddedCities.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
                return true;
            }

            @Override
            public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
                adapterAddedCities.onItemDismiss(viewHolder.getAdapterPosition());
            }

            @Override
            public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
                if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
                    AdapterAddedCities.ViewHolder holder = (AdapterAddedCities.ViewHolder) viewHolder;
                    holder.itemView.setBackgroundColor(Color.LTGRAY);
                }
                super.onSelectedChanged(viewHolder, actionState);
            }

            @Override
            public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
                AdapterAddedCities.ViewHolder holder = (AdapterAddedCities.ViewHolder) viewHolder;
                holder.itemView.setBackgroundColor(0);
            }
        };

        itemTouchHelper = new ItemTouchHelper(callback);
        itemTouchHelper.attachToRecyclerView(addedCitiesRecycler);

Here are a couple of adapter methods that change the dataset and notify the RecyclerView of the change.

public void onItemDismiss(int position) {
        citiesData.remove(position);
        notifyItemRemoved(position);
    }

    public void onItemMove(int fromPosition, int toPosition) {
        CityInfo tmp = citiesData.remove(fromPosition);
        citiesData.add(toPosition > fromPosition ? toPosition - 1 : toPosition, tmp);
        notifyItemMoved(fromPosition, toPosition);
    }

I launched the project from the
article,
everything works fine, I don’t understand what could be the problem.
Maybe I didn't take into account something related to focus on the moved element or deselection?

Answer 1

I updated com.android.support:recyclerview-v7:26.0.0-alpha1to com.android.support:recyclerview-v7:27.0.0in the project and everything worked great.
Most likely it was a bug in the library, so if you encounter a similar problem, just update to the latest version and double-check how the RecyclerView behaves.