Streams: Collectors.minBy and maxBy return an Optional, not a value

Because the source stream might be empty, minBy and maxBy always collect into an Optional wrapping the extreme element under the given Comparator, rather than the element itself.

Code

List<String> words = List.of("pear", "kiwi", "banana", "fig");
Optional<String> shortest = words.stream()
        .collect(Collectors.minBy(Comparator.comparingInt(String::length)));
Optional<String> longest = words.stream()
        .collect(Collectors.maxBy(Comparator.comparingInt(String::length)));
System.out.println("Shortest: " + shortest.get());
System.out.println("Longest: " + longest.get());

Output

Shortest: fig
Longest: banana