How to merge new items with same Header

If I use FlexibleAdapter with sticky Headers, how can I add new List of items to the adapter which may contain Header that is already in the list?

Like:

List<ISectionable> originalItems = new ArrayList();

IHeader headerA1 = new Header(1);
ISectionable itemA1 = new Item(A1);
itemA1.setHeader(headerA1);
originalItems.add(itemA1);

ISectionable itemA2 = new Item(12);
itemA2.setHeader(headerA1);
originalItems.add(itemA2);
// ...originalItems contains more Headers and items as well

FlexibleAdapter adapter = new FlexibleAdapter(originalItems);
// .. setup

List<ISectionable> newItems = new ArrayList();

IHeader headerB1 = new Header(1);
ISectionable itemB1 = new Item(B1);
itemB1.setHeader(headerB1);
newItems.add(itemB1);
// ...newItems contains more headers and items


// How to add newItems to the list to have only one Header(1)?

// Even though headerA1.equals(headerB1) is true, addItems() will result in a second Header(1) added to the list:
adapter.addItems(0, newItems);

So does FlexibleAdapter support some automatic merging of the headers that are equal or do I have to do that manually by using the correct references of the actual header objects? Either by using addItemToSection(), or with addItems() but with replacing headerB1 with headerA1 for the items in newItems before adding them.

Thanks.

[lemonboston]

We don’t really need a sorting and comparison because the items are provided in correct order by our API and I think the Comparator wouldn’t have helped, because as I come to understand the problem is simply that when adding items to a RecycerView to a postion which is visible, it of course shows them and pushes everything down. And because the IHeader was a visible item, adding anything under it naturally pushes the rest down. Only if items are added above it (at position 0), then RecyclerView adds them ‘outside’ of the screen. During trying out different ways to solve this, I finally ‘stumbled upon’ one that worked: simply removing the IHeader item before adding the new items.

This is how I do it now and seems to work:

    private void mergeNewItemsTop(List<IFlexible> newItems)
    {
        IHeader firstDayInCurrent = getFirstHeaderCurrent();
        IHeader lastDayInNew = getLastHeader(newItems);

        if (Objects.equals(lastDayInNew, firstDayInCurrent))
        {
            mFlexibleAdapter.removeItem(mFlexibleAdapter.getGlobalPositionOf(firstDayInCurrent));
            int lastItemWithDistinctHeader = -1;
            for (int i = newItems.size() - 1; i >= 0; i--)
            {
                if (newItems.get(i) instanceof ISectionable)
                {
                    ISectionable item = ((ISectionable) newItems.get(i));
                    if (item.getHeader().equals(lastDayInNew))
                    {
                        item.setHeader(firstDayInCurrent);
                        mFlexibleAdapter.addItemToSection(item, firstDayInCurrent, 0);
                    }
                    else
                    {
                        lastItemWithDistinctHeader = i;
                        break;
                    }
                }
            }
            List<IFlexible> distinctItems = newItems.subList(0, ++lastItemWithDistinctHeader);
            mFlexibleAdapter.addItems(0, distinctItems);
        }
        else
        {
            mFlexibleAdapter.addItems(0, newItems);
        }
    }

[lemonboston]

I am afraid we don’t have time for checking it now thoroughly so I wouldn’t like to touch that code currently unless it’s necessary, to avoid getting bogged down or causing any side effects. But it’s good to hear that there were improvements and thanks for letting me know. I’ll keep in mind to update the version and check back on the workarounds when we need to touch that part of the code base again.

Feel free to close this issue of course, I will create a new one if I encounter anything later.