How to remain at a scroll position in RecyclerView after adding items at its first index and call notifydatasetchange

Question

I am using a RecyclerView, I add items before the first item, the scroll position moves up to the newly first item added. How can I maintain my scroll position after adding new items at its first index and call notifydatasetchange() ?

this is what i do in my adapter

    mCurrentFragment.items.addAll(0, createLineItems(dataArrayList));

    notifyDataSetChanged();

Any suggestions ?

you can calculate it from the ammount of items you inserted and set scroll value manually — filipproch, Oct 08 '15 at 10:03

score 20 · Accepted Answer · edited Dec 14 '15 at 22:31

20

There are two options:

Use the more sophisticated versions of notify

List newData = createLineItems(dataArrayList);
mCurrentFragment.items.addAll(0, newData);
notifyItemRangeInserted(0, newData.size());

Use stable IDs. On your adapter override public long getItemId (int position) to make it return MEANINGFUL values and call setHasStableIds(true); on it.

edited Dec 14 '15 at 22:31

Chad Bingham

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answered Oct 08 '15 at 10:05

Budius

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@Budius What do you mean by MEANINGFUL? does it mean a unique id related to each item? – Hamzeh Soboh May 21 '16 at 07:25
@HamzehSoboh I meant exactly that. If your IDs are just the position (for example) it won't work. It must be (for example) the user ID, or the photo ID, so when the views position changes the ID remains bounded to the data – Budius May 21 '16 at 07:29
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It worked on `notifyItemRangeInserted` but not `setHasStableIds` although `getItemId` was returning `getTime()` for that item's date, which is unique. – Hamzeh Soboh May 21 '16 at 09:37

How to remain at a scroll position in RecyclerView after adding items at its first index and call notifydatasetchange

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