Question

I have a SortedMap (a TreeMap, specifically), from which I extract the values. Later, I need to get the first and last values, as they were ordered in the SortedMap.

SortedMap.values() returns a Collection, whose Iterator preserves order. Therefore, getting the first value is as simple as collection.iterator().next(). However, getting the last value is not so simple — iterating all the way through to get to the last is very inefficient.

Is there a way around this? For now, I’m iterating all the way to the end and storing that value, so I only have to do it once…

Answer 1

If you’re using Java 6 or above, you can use NavigableMap instead of SortedMap, and use its lastEntry method.

Otherwise, you can use SortedMap.get(SortedMap.lastKey()).