Android - Fragment inside a Fragment inside a ViewPager problems

Question

In my application I have a View pager that rotates 4 Fragments. Some of those fragments have other fragments inside them. The first time Viewpager starts a Fragment it works fine, but if I rotate around and return to the previous fragment, the inner fragments fail to show ( and I have noticed that getActivity() in them returns null).

For example, the app starts, I move through viewpager and see all the main fragments and they appear fine, then I scroll back, every main fragment that has inner fragments does not show properly.

I use "FragmentStatePagerAdapter" for my ViewPager and the code is below (variables names are for example).

private class ContentPagerAdapter extends FragmentStatePagerAdapter {

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

    @Override
    public Parcelable saveState() {
        return null;
    }

    @Override
    public Fragment getItem(int pos) {

        Fragment fragment = null;
        try {
            if (pos == POS1) {
                if (fragment1 == null) {
                    fragment1 = Fragment1.newInstance();
                }
                fragment = fragment1;
            } else if (pos == POS2) {
                if (fragment2 == null) {
                    fragment2 = Fragment2.newInstance(something);
                }
                fragment = fragment2;
            } else if (pos == POS3) {
                if ( fragment3 == null ) {
                    fragment3 = Fragment3.newInstance(something3);
                }
                fragment = fragment3;
            } else { //default
                if (fragment4 == null) {
                    fragment4 = Fragment4.newInstance(something4);
                }
                fragment = fragment4;
            }
        }catch (Exception e) {
            Log.e(AppConstants.APP_TAG, "Cannot create fragment", e);
            finish();
        }

        return fragment;
    }

    @Override
    public int getCount() {
        int count = 4;
        return count;
    }

    @Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }
}

I think this might have something to do with `FragmentStatePagerAdapter`s way of handling unused fragments. It destroys the fragment and removes it from the `FragmentManager`. Try using `FragmentPagerAdapter` instead and see how it goes. — JamMaster, Nov 15 '15 at 01:28
Also i found this, seems like it could be of help if you really want to keep the resource friendly `FragmentStatePagerAdapter`. http://stackoverflow.com/questions/16960676/viewpager-in-tabfragment-not-loading-second-time — JamMaster, Nov 15 '15 at 01:41
I tried the FragmentPagerAdapter , it seems to have helped but only a bit. Just a couple fragments worked, some didnt and after a couple of rotations even those dissapeared — Panos, Nov 15 '15 at 01:41
@jammaster - Indeeed!!! I was using the simple getFragmentManager in the main fragment (victim of the copy paste)...!! Now with getChildFragmentManager() it seems to work fine. Please write it as an answer so I can accept it :) — Panos, Nov 15 '15 at 01:49

score 2 · Accepted Answer · edited May 23 '17 at 12:00

2

When instantiating the PagerAdapter, use getChildFragmentManager() instead of getFragmentManager(). If more info needed, similiar problem was solved here ViewPager in TabFragment not loading second time

edited May 23 '17 at 12:00

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answered Nov 15 '15 at 01:53

JamMaster

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Android - Fragment inside a Fragment inside a ViewPager problems

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