I'm working on implementing ViewPager and I want to let the host activity
load the background data (from the Internet) instead of each fragment doing
an independent I/O request.  The reason why is because the same data is
being loaded into two fragments, with the only difference being a category.
 I have two instances of ViewPager in my app, where this scenario holds
true (two different types of data, but each being split by only a
category).  If I can let the host activity fetch the data in the
background, I'll be saving 2 API calls every time the app is used.

I want to let the ViewPager and it's fragments know when to update
themselves when the background load is finished so I can fetch the data
once and pass it down into the fragments.  However, I can't seem to find
any examples of this.  I've tried getting the fragments from the adapter
when the data load is complete, but I'm running into various
synchronization problems.  I've tried calling notifyDataSetChanged on the
adapter (subclass of FragmentPagerAdapter), but it doesn't appear to do
anything.

Another piece to this puzzle is that I'm using ViewPagerIndicator to get
the title effect seen in the Android Market and Google+ apps.  I've tried
not initializing the FragmentPagerAdapter, ViewPager,
and TitlePageIndicator until after the data load is complete, but I'm
seeing the TitlePageIndicator attempt to be drawn anyway and failing when
calculating the bounds since it hasn't been given a ViewPager instance just
yet.

Has anyone else tried to use the ViewPager is this scenario?  I think if I
found a nice outline of how the ViewPager's lifecycle works, I would have
better luck in figuring this workflow out.  Every example I can find lets
the fragments self contain everything, which I completely understand the
reasoning behind and will go that route if necessary but would love to cut
the required network I/O requests if possible.

--
Chris Stewart

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