android - NestedScrollView's fullScroll(View.FOCUS_UP) not working properly

Question

I have a NestedScrollView populated with a vertical LinearLayout, which itself has a bunch of children of various view types: multiple TextViews, two static GridViews, and even a FrameLayout to show a Fragment beneath all of this.

When pressing the back button, if the user has scrolled below a certain point, instead of finishing the Activity, the "scrollToTop" method is called:

public static void scrollToTop(final NestedScrollView scrollview) {
    new Handler().postDelayed(new Runnable() {
        public void run() {
            scrollview.fullScroll(NestedScrollView.FOCUS_UP);
        }
    }, 200);
}

This works in the previous version of my app, which is in the Play Store. But now, after updating my app to target Android Oreo (and updating the support library to version 26.0.2), instead of scrolling to the top, it seems to start scrolling from below the NestedScrollView's original scroll position, and stops where it was. So it just appears as a weird stutter. At some positions, however, it does scroll to the top (albeit very rarely and inconsistently), and others it actually scrolls to the bottom, for what reason I don't understand.

I have been experimenting with view focusability, to no avail. For example, I read that the Static GridViews may interrupt focus while scrolling. I've also tried various different methods to scroll up, such as

scrollview.pageScroll(View.FOCUS_UP);

and

scrollview.smoothScrollTo(0,0);

But nothing seems to work. Is there something wrong with the support library this time around?

Answer 1

try this

add android:descendantFocusability="blocksDescendants" to the LinearLayout inside NestedScrollView and this also

to scroll to top of NestedScrollView use this

NestedScrollView.scrollTo(0, 0);

Edit

Use fling() and smoothScrollTo togather

nestedScrollView.post(new Runnable() {
   @Override
   public void run() {
      nestedScrollView.fling(0);
      nestedScrollView.smoothScrollTo(0, 0);
   }
});