ANSWER:

What you are probably looking for is ViewPager.setOnPageChangeListener

so you can do something like:

myViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() 
            @Override
            public void onPageScrolled(int i, float v, int i2) 

            

            @Override
            public void onPageSelected(int i) 
               fft.execute(i)
            

            @Override
            public void onPageScrollStateChanged(int i) 

            
        });

LuxuryMode from http://stackoverflow.com/questions/16027766