Return String from Java stream

Question

I have a class Person, which stores the code of each person and a list of friends. I'm trying to get the code of the person with the highest number of friends, but cannot figure it out. The methods getFriends and getCode are provided by the Person class.

How can I return a string from the stream?

HashMap<String,Person> persons = new HashMap<>();

public String personWithLargestNumberOfFriends() {
    return persons.values().stream()
        .sorted(comparing(p -> ((Person)p).getFriends().size()).reversed())
        .limit(1)
        .forEach(p -> ((Person)p).getCode());
}

Regardless of what you want to do with a Stream, as soon as you forget about the existence of forEach, solutions will arise… — Holger
– Holger, Commented Jun 27, 2016 at 11:57

castletheperson · Accepted Answer · 2016-06-25 22:27:16Z

6

Instead of sorting, use max().

return persons.values().stream()
    .max(comparing(Person::getFriends, comparingInt(List::size)))
    .map(Person::getCode)
    .orElse("empty code");

See the Optional class to see if some other getter would suit your needs, like orElseThrow().

edited Jun 25, 2016 at 22:27

answered Jun 25, 2016 at 1:49

castletheperson

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