Scroll position in article list is not remembered when I scrolled after 300+ items

[shunf4]

1. Open app
2. In article list, keep scrolling until you go past 300+ items
3. Click on one item on screen to read it
4. Go back to the article list
5. Scroll position is not restored; now the position is around the 300th item

[Shinokuni]

It sounds it's related to Androidx paging library. I got some problems with this library, I hope 3.0 will be better quality though.

[shunf4]

Enabling placeholders in buildPagedList() will fix this. https://github.com/readrops/Readrops/blob/28dda2f1b514a470cd6a12a11bcc717b200e8bdb/app/src/main/java/com/readrops/app/itemslist/MainViewModel.java#L75

In addition, we should check for null after getItem(position) in getPreloadItems since it now can be null.https://github.com/readrops/Readrops/blob/28dda2f1b514a470cd6a12a11bcc717b200e8bdb/app/src/main/java/com/readrops/app/itemslist/MainItemListAdapter.java#L221

Will there be other side effects?

[Shinokuni]

When I implemented the paging library, I didn't want to handle null items and as the scrolling bar behavior didn't bother me, I disabled the placeholders.

Are you sure this will fix the bug?

[shunf4]

Are you sure this will fix the bug?

Yes.

Another place to take care of https://github.com/readrops/Readrops/blob/28dda2f1b514a470cd6a12a11bcc717b200e8bdb/app/src/main/java/com/readrops/app/itemslist/MainItemListAdapter.java#L153

Then I believe at least there would not be any NullPointerException crash. I've been using my modified version and so far, so good.