Android View Pager Adapter shows empty screen

Question

I am implementing Pager Adapter in a Fragment. When I load the screen First time, it works fine. If i switch to other fragment and goes to previous fragment again the it shows empty screen. If I swipe between different tap and move to first tab again then it shows data.

I think on moving back the tabs which are visible didn't load data but once they are out of view during swipe navigation it loads data.

Here is my Pager Adapter:

public class MyPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int index) {
        switch (index) {
        case 0:
            return new Fragment1();
        case 1:
            return new Fragment2();
        case 2:
            return new Fragment3();
        case 3:
            return new Fragment4();
        case 4:
            return new Fragment5();
        case 5:
            return new Fragment6();
        }

        return null;
    }

    @Override
    public int getCount() {
        return 6;
    }
}

I am setting my adapter like this:

viewPager = (ViewPager) rootView.findViewById(R.id.my_pager);
        mAdapter = new MyPagerAdapter(getActivity().getSupportFragmentManager());
        viewPager.setAdapter(mAdapter);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);        

Answer 1

I was having the same problem and wasted a whole day on this. So I am posting the solution for my issue so that someone else doesn't have to struggle and waste a lot of time.

My problem was that the Fragments inside viewpager were getting invoked(debugger was getting hit) but I was not able to see it in the view(Even for the 1st time).

Issues were:

1. The parent of the ViewPager was a Fragment.

I had to use getChildFragmentManager() instead of getFragmentManager().

2. The parent of the Parent Fragment was a NestedScrollView(The activity in which Fragment was populated).

For some reason, even if we keep the height and width of viewpager as matchparent, it was not getting picked up and was defaulted to 0(Even though it was filled in the preview of the xml). To fix this, we have to add android:fillViewport="true" in your NestedScrollView

Hopefully someone will find this helpfull :)