android - Diffutil in recycleview, making it autoscroll if a new item is added

Question

If we use DiffUtil.Callback, and do

adapter.setItems(itemList);
diff.dispatchUpdatesTo(adapter);

how can we make sure that adding of new elements will scroll to that new position.

I have a case where I see item disappear, and a new one is created as a first element at the top, but not visible. It is hidden on top until you scroll down to make it visible. Before using DiffUtil, I was implementing this manually, and after I knew I was inserting at some position (on top) I could scroll to.

Answer 1

There's an easy way to do this that also preserves the user's scroll position if items are inserted outside the viewable area:

import android.os.Parcelable;

Parcelable recyclerViewState = recyclerView.getLayoutManager().onSaveInstanceState();
// apply diff result here (dispatch updates to the adapter)
recyclerView.getLayoutManager().onRestoreInstanceState(recyclerViewState);              

Using this approach, the new items are made visible if they are inserted where the user can see them -- but the user's viewpoint is preserved if the items are inserted outside of view.