rantravee rantravee - 5 months ago 113
Android Question

Maintain/Save/Restore scroll position when returning to a ListView

I have a long

ListView
that the user can scroll around before returning to the previous screen. When the user opens this
ListView
again, I want the list to be scrolled to the same point that it was previously. Any ideas on how to achieve this?

ian ian
Answer

Try this:

// save index and top position
int index = mList.getFirstVisiblePosition();
View v = mList.getChildAt(0);
int top = (v == null) ? 0 : (v.getTop() - mList.getPaddingTop());

// ...

// restore index and position
mList.setSelectionFromTop(index, top);

Explanation:

ListView.getFirstVisiblePosition() returns the top visible list item. But this item may be partially scrolled out of view, and if you want to restore the exact scroll position of the list you need to get this offset. So ListView.getChildAt(0) returns the View for the top list item, and then View.getTop() - mList.getPaddingTop() returns its relative offset from the top of the ListView. Then, to restore the ListView's scroll position, we call ListView.setSelectionFromTop() with the index of the item we want and an offset to position its top edge from the top of the ListView.