public class CustomScrollView extends ScrollView {
    private GestureDetector mGestureDetector;
    View.OnTouchListener mGestureListener;   

    public CustomScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mGestureDetector = new GestureDetector(new YScrollDetector());
        setFadingEdgeLength(0);
    }   

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return super.onInterceptTouchEvent(ev) && mGestureDetector.onTouchEvent(ev);
    }   

    // Return false if we're scrolling in the x direction
    class YScrollDetector extends SimpleOnGestureListener {
        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            if(Math.abs(distanceY) > Math.abs(distanceX)) {
                return true;
            }
            return false;
        }
    }
}