In my Activity, I change the underlying data HashMap for my ExpandableListView, and then call
((BaseAdapter) myExpandableListView.getAdapter()).notifyDataSetChanged();
However, the app crashes after calling this, raising an IndexOutOfBoundsException.
I double-checked that I access the same and right data everywhere in the adapter, but could not find any mistakes.
After a bit of debugging, I finally found out that, strangely enough, getChildrenCount is never called after I called notifyDataSetChanged. Thus, the Adapter is still expecting to get the same number of children as there were before the update.
As I removed some children, that's a wrong assumption, and leads to the IndexOutOfBoundsException.
After a bit of playing around, I discovered that for ExpandableListViews, the Adapter has to be accessed via getExpandableListAdapter(), not via getAdapter().
After changing my code to
((BaseExpandableListAdapter) myExpandableListView.getExpandableListAdapter()).notifyDataSetChanged();
Everything works fine now.
I hope this helps any fellow developers. I spent a few hours finding and fixing this, and hardly found any information about it on the web and StackOverflow.