Fragment doesn't show properly in ViewPager

Question

I have an Activity with a traditionnal viewpager component. This viewpager contains MainFragment class (it's a standard fragment). This is the layout of this fragment:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@+id/fragment_container"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:layout_weight="1">
</FrameLayout>

Ps: I need to use this framelayout because I can switch with 2 fragments inside according an user data.

In this MainFragment I want to show a specific fragment according an user data:

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        final Bundle bundle = getArguments();
        int mydata = bundle.getInt(BUNDLE_KEY_MY_DATA);

        if (mydata == 1)
            addFragment(Fragment1.newInstance(), Fragment1.TAG);
        else if (mydata == 2)
            addFragment(Fragment2.newInstance(), Fragment2.TAG);
    }

My addFragment method:

protected void addFragment(@NonNull Fragment fragment,
                           @NonNull String fragmentTag) {
    getFragmentManager()
            .beginTransaction()
            .add(R.id.fragment_container, fragment, fragmentTag)
            .disallowAddToBackStack()
            .commit();
}

But there is a strange behavior during execution (no crash!). For example in my tab (associated with the viewpager) there are these elements: "1" "2" "3" "4" "5" "6" "7"

So the default position is on element "4"; it works perfectly. Now if I swipe for example to "3", the Fragment1 (or Fragment2 doesn't matter) doesn't appear. To show it, I must to swipe again (so to "2"), then come back to "3" and the fragment appears correctly.

Thanks for your help guys!

Answer 1

Use Fragment.getChildFragmentManager() in your addFragment().