Android ListView scrolling to top

Question

Hi,

I have a ListView with custom rows. When any of these rows is clicked, the ListView's data is regenerated. I'd like the list to scroll back to the top when this happens.

I initially tried using setSelection(0) in each row's OnClickListener to achieve this but was unsuccessful (I believe because the ListView loses its scroll position when its data is invalidated - so my call to setSelection is undone. I still don't understand how the ListView decides where to scroll to after invalidation, though).

The only working solution I know of was given by Romain Guy here: http://groups.google.com/group/android-developers/browse_thread/thread/127ca57414035301

It involves (View.post)ing the call to _listView.setSelection(0). I found this to perform quite poorly. The newly generated list shows up with its scroll location unchanged and there is a considerable delay before it scrolls back to the top.

Is there any better way to achieve this functionality?

Any help would be much appreciated.

Thanks!

Answer 1

Personally, I recommend you find a different UI pattern. It is possible that users will find your current "click, and the list changes in situ" approach intuitive, but I am skeptical.

You could try subclassing ListView and overriding layoutChildren() to chain to the superclass, then call setSelection(0) in the case where that is needed. If the "considerable delay" is due to just the post() call, this should clear it up.

Answer 2

hi, as a workaround, you can create a new adapter containing the new regenerated data, then call ListView.setAdapter. after that call ListView.setSelection(n).

btw, the solution provided by commonsware is worked.