如何在notifyDataSetChanged之后阻止RecyclerView中的自动滚动？

Question

I have a RecyclerView with several items types. It looks like this:

• 07/21/2017
• Message 1
• Message 2
• Message 3
• 07/22/2017
• Message 4
• New messages header
• Message 5
• Message 6

When new messages arrived I sort it by date and call notifyDataSetChanged() . It works well, but it automatically scroll my RecyclerView on new item(s) height. In this case I cannot use notifyItemInserted() because I don't know item position after sorting.

How to force RecyclerView do not scroll after notifyDataSetChanged() without call notifyItemInserted() ?

Answer 1

There are 4 ways you can try. Because I don't know what is the height of your view, so I can't sure if it really works. But let give it a try

I. You don't which specific item could be changed. But you know the range of that change

mAdapter.notifyItemInserted(position);                 
mAdapter.notifyItemRangeChanged(0, list.size());

II. Clear list before call notifyDataSetChanged()

yourList.clear();
mAdapter.notifyDataSetChanged();

III. Save/Reset state of ReyclerView before/after adding new item

    // Save state
    private Parcelable recyclerViewState;
    recyclerViewState = recyclerView.getLayoutManager().onSaveInstanceState();

    // Restore state
    recyclerView.getLayoutManager().onRestoreInstanceState(recyclerViewState);

IV. Use this function

mAdapter.notifyItemRangeChanged(0, list.size());

Answer 2

Have you played with myRecView.getLayoutManager().setStackFromEnd(boolean) ?

If you can determine if the new item has been inserted after sorting above or below the visible part and in function of this call setStackFromEnd () with true or false maybe you can avoid the scroll.

I do not know if it will really work ....

Answer 3

You can know where the new item has been inserted using list.indexOf(yourItem) on your list of items. Then you can call notifyItemInserted()