@Test
public void _03_filter() {
Stream<String> longWords = words.stream().filter(w -> w.length() > 12);
Optional<String> first = longWords.findFirst();
assertThat(first.isPresent(), is(true));
assertThat(first.get(), is("conversations"));
}
@Test
public void shouldFindFirst() {
Stream<Fruit> fruits = asList(new Fruit(APPLE), new Fruit(GRAPE)).stream();
Optional<Fruit> first = fruits.findFirst();
if (first.isPresent()) {
Fruit firstFruit = first.get();
assertThat(firstFruit.getName()).isEqualTo(APPLE);
} else fail("should've find apple.");
}
@Test
public void _04_서브스트림_추출() {
// limit
Stream<Double> randoms = Stream.generate(Math::random).limit(100);
assertThat(randoms.count(), is(100L));
// skip
Stream<String> words = Stream.of(contents.split("[\\P{L}]+")).skip(1);
assertThat(words.findFirst().get(), is("was"));
}
@Test
public void _05_상태유지변환_StatefulTransformation() {
// distinct는 이전 값을 기억하고 있어야 한다.
Stream<String> uniqueWords =
Stream.of("merrily", "merrily", "merrily", "gently", "merrily").distinct();
final List<String> actual = uniqueWords.collect(Collectors.toList());
assertThat(actual.get(0), is("merrily"));
assertThat(actual.get(1), is("gently"));
// sort도 이전 값을 기억하고 있어야한다. (전체 값을 다 알고 있어야..)
Stream<String> longestFirst =
words.stream().sorted(Comparator.comparing(String::length).reversed());
final Optional<String> longestFirstFirst = longestFirst.findFirst();
assertThat(longestFirstFirst.get(), is("disappointment"));
}