FragmentStatePagerAdapter getCount() is not called

Question

I am using FragmentStatePagerAdapter in my app. My problem is that when I am doing notifyDataSetChanged() it's calling only the getCount() and not the getItem(). the getCount is not returning 0. this is my FragmentStatePagerAdapter:

private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {

    public ScreenSlidePagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return titles.get(position);
    }

    @Override
    public Fragment getItem(int position) {
        return fragmentList.get(position);
    }

    @Override
    public int getCount() {
        return fragmentList.size();
    }
}

How could it be that after pagerAdapter.notifyDataSetChanged(); only the getCount() is called and the getItem(int position) is not being called after it? Thanks!

Are there any real changes in the fragment list? If not, `getItem()` should not be called. getCount() is called just routine call of the first checks if the size is changed. — Nikola Despotoski, Dec 24 '13 at 16:23
How can the getItem() know if there is a change or not?! In any case, the size of the fragmentList is changing... — roiberg, Dec 24 '13 at 16:27
Once there are changes and those changes need to be populated , get item is called. Thats what i meant. — Nikola Despotoski, Dec 24 '13 at 16:28

score 0 · Answer 1 · answered Apr 29 '14 at 06:37

From Issue 19001, I found that int getItemPosition(Object object) needs to be implemented in the FragmentStatePageAdapter subclass. By default this method is assumed to return POSITION_UNCHANGED which will not trigger getItem to be called. However, I, also, ran into issues (possible bugs in the android support library) when I implemented anything other than return POSITION_NONE.

Snippet from my adapter:

@Override
public Fragment getItem(int position) {
    return DiceRollerFragment.instantiate(position);
}

FragmentStatePagerAdapter getCount() is not called

1 Answers1