Why it is not possible to use ViewPager within a Fragment? It actually is

To implement the View pager within a fragment use getChildFragmentManager() instead of getFragmentManager(). You can call setAdapter() for the ViewPager from onCreateView() or onViewCreated(), that is not a matter.

I hope this will help you guys.

UPDATE: Since this answer was originally written, you now can have nested fragments, which means it is possible to have a ViewPager use fragments for pages and be in a fragment itself. This sample project demonstrates the technique.

I now return you to your regularly-scheduled answer, presented in its entirety...

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Quoting myself from the book:

The simplest way to use a ViewPager is to have it page fragments in and out of the screen based on user swipes. This only works if the ViewPager itself is not contained within a fragment, as you cannot have fragments nested inside of other fragments.

Quoting Dianne Hackborn:

Nested fragments are not currently supported. Trying to put a fragment within the UI of another fragment will result in undefined and likely broken behavior.

It is perfectly possible to put a ViewPager inside a Fragment, so long as the contents of the ViewPager do not themselves contain fragments. Since the concrete implementations of PagerAdapter supplied by the Android Support package use fragments, you have to roll your own fragment-less PagerAdapter to put the ViewPager in a fragment.

I will endeavor to make this point clearer in the next edition of the book (unless you're British, in which case I'll endeavour to make this point clearer :-).

While Initializing the SetionPageAdapter for ViewPager use "getChildFragmentManager()".

mSectionsPagerAdapter = new SectionsPagerAdapter(getChildFragmentManager());