Changing the scroll size of Android makes the view move to the bottom of the scrollview

Question

I have a scrollview whose height is initially initialized with an approximate length, and I set it ScrollViewfullScroll(ScrollView.FOCUS_UP)so that it starts from the bottom. This works just fine as expected.

Now in the drawing process (when I scroll up) I determine the exact size of the scrollview and reset its layoutparams. The problem is that now the chart is moving to the bottom. How to avoid moving the scroll at the bottom?