ViewPager does not redraw content, remains/turns blank

Question

We're suffering from a very strange issue with ViewPager here. We embed lists on each ViewPager page, and trigger notifyDataSetChanged both on the list adapter and the view pager adapter when updating list data.

What we observe is that sometimes, the page does not update its view tree, i.e. remains blank, or sometimes even disappears when paging to it. When paging back and forth a few times, the content will suddenly reappear. It seems as if Android is missing a view update here. I also noticed that when debugging with hierarchy viewer, selecting a view will always make it reappear, apparently because hierarchy viewer forces the selected view to redraw itself.

I could not make this work programmatically though; invalidating the list view, or the entire view pager even, had no effect.

This is with the compatibility-v4_r7 library. I also tried to use the latest revision, since it claims to fix many issues related to view pager, but it made matters even worse (for instance, gestures were broken so that it wouldn't let me page through all pages anymore sometimes.)

Is anyone else running into these issues, too, or do you have an idea of what could be causing this?

Answer 1

If the ViewPager is set inside a Fragment with a FragmentPagerAdapter, use getChildFragmentManager() instead of getSupportFragmentManager() as the parameter to initialize your FragmentPagerAdapter.

mAdapter = new MyFragmentPagerAdapter(getChildFragmentManager()); 

Instead of

mAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager());