MoreCollectors Sınıfı

onlyElement metodu
Açıklaması şöyle.

With this API, the Collector takes a stream containing just one element and returns the element; if the stream contains more than one element it throws IllegalArgumentException or if the stream contains zero element it throws NoSuchElementException.

Örnek
Şöyle yaparız.

import static com.google.common.collect.MoreCollectors.onlyElement;

User match =
    users.stream().filter((user) -> user.getId() < 0).collect(onlyElement());