Question

Is this how to implement ascending sort when the comparator sorts descending?

// Sorts the emails alphabetically by subject in ascending order.
public void sortBySubjectAscending()
{
Collections.sort(emails, Collections.reverseOrder(new Email.SubjectDescendingComparator()));
}

Answer 1

Yes, it does. If you reverse a descending comparator, you get an ascending comparator.

To break it down, this is what you are doing:

Comparator ascending = Collections.reverseOrder(new Email.SubjectDescendingComparator());
Collections.sort(emails, ascending);