How to collapse all other expanded groups after changing a collapsed one to be expanded in ExpandableListView?

I created an ExpandableListView with a custom adapter and all works perfectly including the click, collapse and expand events. If anyone needs assistance with the expandable listview I followed the tutorial at: http://www.androidhive.info/2013/07/android-expandable-list-view-tutorial/.

I now want to write code in my setOnGroupExpandListener method to collapse all other Groups that are open apart from the one that is currently focussed. (Content aware - in a sense) To clarify, if I have the following:

Item 1

• Sub Item 1
• Sub Item 2

Item 2

• Sub Item 1

Item 3

• Sub Item 1
• Sub Item 2

If I click on Item 1, it should expand Item 1 (this already works) and it should collapse Item 2 and Item 3 groups for me. Is this possible and how can I achieve that?

Here is my current setOnGroupExpandListener:

    gpsMenuListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
        @Override
        public void onGroupExpand(int groupPosition) {
            Toast.makeText(getApplicationContext(), "Expanded: " + gpsMenuListDataHeader.get(groupPosition).toString(), Toast.LENGTH_SHORT).show();
        }
    });

As you can see I currently only have a Toast that prints a message but I want to add the collapse functionality.

listView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
            @Override
            public void onGroupExpand(int groupPosition) {
                YourExpandableListAdapter customExpandAdapter = (YourExpandableListAdapter)listView.getExpandableListAdapter();
                if (customExpandAdapter == null) {return;}
                for (int i = 0; i < customExpandAdapter.getGroupCount(); i++) {
                    if (i != groupPosition) {
                        listView.collapseGroup(i);
                    }
                }
            }
        });