Android scrollview onScrollChanged

Question

I have a fixed content in my text view inside a scroll view. When the user scrolls to a certain position, I would like to start an activity or trigger a Toast.<

Answer 1

NestedScrollView is just like android.widget.ScrollView, but it supports acting as both a nested scrolling parent and child on both new and old versions of Android.

1st - Use NestedScrollView binding instead ScrollView

2nd - Set Scroll listener, like this, to detect axis Y moving for a headerView by example

    nestedScrollView.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {

        @Override
        public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
            Log.d(TAG, "onScrollChangeForY - scrollY: " + scrollY + " oldScrollY: " + oldScrollY);

            int MOVE = -1, SCROLL_UP = 0, SCROLL_DOWN = 1;
            float initialPositionY = headerView.getY();

            MOVE = scrollY > oldScrollY ? SCROLL_UP : SCROLL_DOWN;

            if (MOVE == SCROLL_UP) {

                int incrementY = scrollY - oldScrollY;

                headerView.setY(initialPositionY - incrementY);

            } else {

                int incrementY = oldScrollY - scrollY;

                headerView.setY(initialPositionY + incrementY);
            }
        }
    });