android - How to keep ExpandableListView in expanded status?

Question

I use

SimpleExpandableListAdapter

in my

ExpandableListActivity

When user click the group row, the children list is expanded and show, when user click each child item in the expanded list, user will be navigated to the next second_Activity. Currently, when user click the back button to go back from second_Activity to the ExpandableListActivity, the expandable list is initialized as un-expanded, I would like the expandable list keep in expanded status, so that user know previously which item he has selected. How to do that? Which method from ExpandableListActivity should be override?

PS: I know I should put getExpandableListView().expandGroup(groupPosition); somewhere, but where? I tried to put this code in onGroupClick() and onChildClick(), but this does not help.

Answer 1

For always expanded groups, I extend SimpleExpandableListAdapter and set the group to be expanded in the getGroupView method:

@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
    View v = super.getGroupView(groupPosition, isExpanded, convertView, parent);
    ExpandableListView eLV = (ExpandableListView) parent;
    eLV.expandGroup(groupPosition);
    return v;
}