IssueTracker

Good catch, that builder concept was removed to simplify things a while back, and we missed updating the ListAdapterHelper and PagedListAdapterHelper javadocs. Should be:

 class UserAdapter extends RecyclerView.Adapter<UserViewHolder> {
     private final ListAdapterHelper<User> mHelper
             = new ListAdapterHelper(this, User.DIFF_CALLBACK);

Fixed, will go out with next docs push.

That's not quite right either, I don't believe.

The constructor is:

    public ListAdapterHelper(ListUpdateCallback listUpdateCallback,
            ListAdapterConfig<T> config) {
        mUpdateCallback = listUpdateCallback;
        mConfig = config;
    }

so UserAdapter would need to implement ListUpdateCallback and you would need to pass a ListAdapterConfig instead of the DIFF_CALLBACK.


What I needed to do to get is to work is:

    mHelper = new ListAdapterHelper<>(new AdapterCallback(this),
      new ListAdapterConfig.Builder<T>().setDiffCallback(diffCallback).build());

where AdapterCallback was copied from ListAdapterHelper.AdapterCallback because it is scoped to the arch library:

Is there a reason why it is so restricted? It seems like it is only useful then if you extend from ListAdapter which just wraps ListAdapterHelper in the same library.

    /**
     * Default ListUpdateCallback that dispatches directly to an adapter. Can be replaced by a
     * custom ListUpdateCallback if e.g. your adapter has a header in it, and so has an offset
     * between list positions and adapter positions.
     *
     * @hide
     */
    @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
    public static class AdapterCallback implements ListUpdateCallback {
        private final RecyclerView.Adapter mAdapter;

        public AdapterCallback(RecyclerView.Adapter adapter) {
            mAdapter = adapter;
        }

        @Override
        public void onInserted(int position, int count) {
            mAdapter.notifyItemRangeInserted(position, count);
        }

        @Override
        public void onRemoved(int position, int count) {
            mAdapter.notifyItemRangeRemoved(position, count);
        }

        @Override
        public void onMoved(int fromPosition, int toPosition) {
            mAdapter.notifyItemMoved(fromPosition, toPosition);
        }

        @Override
        public void onChanged(int position, int count, Object payload) {
            mAdapter.notifyItemRangeChanged(position, count, payload);
        }
    }

Good catch - Reopening to fix ListAdapter to have the same Adapter.this constructor as PagedListAdapterHelper.

The reason it's restricted is that it doesn't belong in the Paging library - we should first move it to be alongside DiffUtil, and work it into a support library release. In the meantime, can copy the code, but filed https://issuetracker.google.com/issues/72333852 to track the helper public - thanks for bringing it up.

Fix is in, will go out with next release.

Released with paging alpha 6 / support library 27.1.0, see:

New constructor in AsyncListDiffer (rename of ListAdapterHelper): https://developer.android.com/reference/android/support/v7/recyclerview/extensions/AsyncListDiffer.html#AsyncListDiffer(android.support.v7.widget.RecyclerView.Adapter, android.support.v7.util.DiffUtil.ItemCallback<T>)


AdapterListUpdateCallback, so you don't have to copy it out: https://developer.android.com/reference/android/support/v7/util/AdapterListUpdateCallback.html