Is there an event called by changing the count of items in the recyclerview?

Question

Is there an event called by changing the count of items in the recyclerview?

I want to call function every time recyclerview items are added.

Answer 1

Update:

It turns out I misunderstood the original question. What was really asked is how to get notified when the underlying data in an Adapter has changed.

For this you could use a RecyclerView.AdapterDataObserver in conjunction with RecyclerView.Adapter's registerAdapterDataObserver(AdapterDataObserver observer) method to register for changes in the underlying list data.

Original Answer:

Your RecyclerView is backed by a RecyclerView.Adapter which owns the actual list of items being displayed.

If you change the backing list, you should call one of the notifyXXX methods on your adapter to notify your RecyclerView what has changed (and optionally where in the list the change happened.)

At the very least, you could call notifyDataSetChanged on your adapter to tell your RecyclerView that something somewhere in the list has changed. This can be expensive since you're not being specific about what changed, so the RecyclerView has to query the adapter for more information and potentially redraw its entire client area of items.

Something like:

RecyclerView.Adapter adapter = recyclerView.getAdapter();
if (adapter != null) {
    adapter.notifyDataSetChanged();
}

Behind the scenes, the RecyclerView will call the RecyclerView.Adapter#getItemCount() method on the Adapter to determine what the current item count is.