android load more items from listview issue

Question

I have a listview, i've edited the adapter, so the last item will always be a button with the text 'Load More'. The items of the listview are some posts, that are stored on a server. (Currently using Parse, but this doesn't matter)

Everytime I load items to the listview, I do a request to the server, and get let's say 15 posts, sorted by the date descending. So the first request will give me the last 15 posts added. When I click add more, it will do a request for the next 15 posts added, by skipping 15. If I click again , it will do a request for the next 15 posts by skipping 30 posts, and so on.

This method works perfectly if no one ads a new post while scrolling. But if this happens, I would get some of the posts that I already have..

What should I do to handle new posts using this method? Or is there a better one?

Answer 1

If you can edit your web service's code then a good guideline to handle paginating can be found in the Twitter devs documentation/Working with Timelines . It is a good place to start.

If you can't then the only thing that I can think of is checking the posts id (if it has one, or create a local identifier for each one of them) before adding the post you your adapter's data. If it's already there then you skip it and just move to the next one.