Question

I’m working on a conference application where we want the sessions to be first grouped by time and then by room location. I have successfully sorted by one or the other in my ExpandableListActivity, but have been unsuccessful with both the primary and secondary sort.

_{(source: coreylatislaw.com)}

Set up

• Custom content provider (extends ContentProvider)
• Custom list adapter (extends BaseExpandableListAdapter)
• Custom list activity (extends ExpandableListActivity)

Query

    Cursor cursor = context.getContentResolver()
                           .query(uri,
                                  ScheduleData.PROJECTION,
                                  null,
                                  null,
                                  ScheduleData.SORT_ORDER);

Sort order

    public static final String SORT_ORDER = TimeSlots.QUALIFIED_TIMESTART + " ASC"; // timeslots.timestart

Failed primary & secondary sort orders

    public static final String SORT_ORDER = TimeSlots.QUALIFIED_TIMESTART + " ASC, " + Locations.QUALIFIED_NAME + " ASC"; // timeslots.timestart ASC, locations.name ASC
    public static final String SORT_ORDER = TimeSlots.QUALIFIED_TIMESTART + ", " + Locations.QUALIFIED_NAME + " ASC";     // timeslots.timestart, locations.name ASC

The second clause seems to have no affect on the ordering. Is this a limitation of the ExpandableListActivity? Should I specify multiple sort order items differently?

Answer 1

Turns out that there was a comparator in the class that was overriding the sort order specified in the ORDERBY clause. When using the ORDERBY clauses above with out the comparator, I got the desired sorting. You can do it either way, but I’m killing the extra code and choosing the ORDERBY clause.

The comparator path:

// Sort children
Collections.sort(group.children, CHILD_COMPARATOR);

// Specify sort by location
static final Comparator<Child> CHILD_COMPARATOR = new Comparator<Child>()
{
    @Override
    public int compare (Child child1, Child child2)
    {
        return child1.location.toLowerCase().compareTo(child2.location.toLowerCase());
    }
};