How to get the last 25 elements of a SortedSet?

Question

In Java I have a SortedSet that may have 100,000 elements. I would like to efficiently and elegantly get the last 25 elements. I'm a bit puzzled.

To get the first 25 I'd iterate and stop after 25 elements. But I don't know how to iterate in reverse order. Any ideas?

SortedSet<Integer> summaries = getSortedSet();
// what goes here :-(

Answer 1

Throw the Set into a List and use subList(). I'm not sure how performant it is to create the List, so you'd have to run some tests. It'd certainly make the coding easy though.

    List f = new ArrayList( summaries);
    List lastTwentyFive = f.subList( summaries.size() - 25, summaries.size() );