IssueTracker

I'm developing an application intended to be controlled both "by touch" and "by mouse".
I came across very annoying behavior when ListView scroll-y position is reset to zero after each adapter.notifyDataSetChanged().
In my scenario this happens approximately every 5 seconds (rate of data update).

I've spent few hours digging through the Android sources and problems seems to be somewhere here (note: I'm developing at 8.1, but I see same code in 9.0 codebase)
https://android.googlesource.com/platform/frameworks/base/+/refs/tags/android-9.0.0_r35/core/java/android/widget/AdapterView.java#1254

            if (mSelectedPosition >= 0) {
                // Sync the selection state
                View v = getChildAt(mSelectedPosition - mFirstPosition);
                mSyncRowId = mNextSelectedRowId;
                mSyncPosition = mNextSelectedPosition;
                if (v != null) {
                    mSpecificTop = v.getTop();
                }
                mSyncMode = SYNC_SELECTED_POSITION;
            } else ...

- when list view is created and filled - it gets auto-selected item at zero-position
- when I mousewheel-scroll the view - 'mFirstPosition' gets some positive number (e.g. 10), whereas 'mSelectedPosition' is zero.
  That is why expression "mSelectedPosition - mFirstPosition" is always negative and getChildAt() always returns null.
  This consecutively causes "mSpecificTop" to be always zero - and that is the position being restored after "adapter.notifyDataSetChanged()",
  see here https://android.googlesource.com/platform/frameworks/base/+/refs/tags/android-9.0.0_r35/core/java/android/widget/ListView.java#1790

  So ... I think this is the bug to be fixed somehow.
 
- Next ... i was curios why problem does not occur when Listview "is scrolled by touch" and came to this code
  https://android.googlesource.com/platform/frameworks/base/+/refs/tags/android-9.0.0_r35/core/java/android/widget/AbsListView.java#3738
 
    @Override
    public void onTouchModeChanged(boolean isInTouchMode) {
        if (isInTouchMode) {
            // Get rid of the selection when we enter touch mode
            hideSelector();

   And I see here that touch-scroll always clears selection (what is somewhat strange to my mind),
   but in context of that problem this causes "if (mSelectedPosition >= 0) {" mentioned earlier to be always false after touch-scroll and `mSpecificTop` is evaluated correctly in 'else' branch.
   
   So ... this allows a counter-intuitive workaround: call `listView.onTouchModeChanged(true);` before `adapter.notifyDataSetChanged();`


Please take care about this problem.
Demo project to reproduce it is attached.