Java Stream: find an element with a min/max value of an attribute

Question

I have a stream of objects and I would like to find the one with a maximal value of some attribute that\'s expensive to calculate.

As a specific simple example, say

Answer 1

How about using two streams, one to create a map with the pre-calculated values and a second using the map's entry set to find the max value:

        String coolestString = stringList
            .stream()
            .collect(Collectors.toMap(Function.identity(), Test::coolnessIndex))
            .entrySet()
            .stream()
            .max((s1, s2) -> Integer.compare(s1.getValue(), s2.getValue()))
            .orElse(null)
            .getKey();