set ViewPager.setOnPageChangeListener
on your viewpager.
Some thing like this-
myViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int i, float v, int i2) {
}
@Override
public void onPageSelected(int i) {
// here you will get the position of selected page
}
@Override
public void onPageScrollStateChanged(int i) {
}
});