Toggle groups in expandable listview

Question

I'm building an expandable listview, in which I want only one group to be expanded at a time.

For the time being I've only 2 groups in my listview. When the user clicks on a group, the other one should collapse and vice versa. Also, the same should be retained during orientation changes.

Activity Class:

private String selectedGroupPosition = null;

Orientation Change:

@Override
public void onConfigurationChanged(Configuration newConfig)
{
   super.onConfigurationChanged(newConfig);
   initUI();            
}

initUI():

if(selectedGroupPosition!=null) {           
   expListView.expandGroup(Integer.parseInt(selectedGroupPosition));
}

........

expListView.setOnGroupClickListener(new OnGroupClickListener() {
     @Override
     public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
        parent.smoothScrollToPosition(groupPosition);

        if (groupPosition==0) {
           if(parent.isGroupExpanded(1))
              parent.collapseGroup(1);
        } 
        else if (groupPosition==1) {
            if(parent.isGroupExpanded(0))
              parent.collapseGroup(0);
        }

         selectedGroupPosition = ""+groupPosition;
         return false;
     }
 });

However, this code does not seem to work. When I click on the 1st group, it expands. Next when I click on the 2nd group, the 1st group collapses but the 2nd one does NOT expand. (it only expands on a subsequent click)

But if I do an orientation change at this point of time the 2nd group expands.

Why is this so?

Answer 1

There's no such thing out-of-box, but you can build it yourself pretty easily. You need to add the listener to collapse the previously openned group:

expListView.setOnGroupExpandListener( new OnGroupExpandListener() {
  int previousGroup = -1;

  @Override public void onGroupExpand( int groupPosition ) {
    if( groupPosition != previousGroup ) expListView.collapseGroup( previousGroup );
    previousGroup = groupPosition;
  }
} );