@Test
public void testFirstLast() {
Supplier<Stream<Integer>> s = () -> IntStreamEx.range(1000).boxed();
checkShortCircuitCollector("first", Optional.of(0), 1, s, MoreCollectors.first());
checkShortCircuitCollector(
"firstLong",
Optional.of(0),
1,
() -> Stream.of(1).flatMap(x -> IntStream.range(0, 1000000000).boxed()),
MoreCollectors.first(),
true);
checkShortCircuitCollector(
"first",
Optional.of(1),
1,
() -> Stream.iterate(1, x -> x + 1),
MoreCollectors.first(),
true);
assertEquals(
1, (int) StreamEx.iterate(1, x -> x + 1).parallel().collect(MoreCollectors.first()).get());
checkCollector("last", Optional.of(999), s, MoreCollectors.last());
checkCollectorEmpty("first", Optional.empty(), MoreCollectors.first());
checkCollectorEmpty("last", Optional.empty(), MoreCollectors.last());
}
@Test
public void testMapping() {
List<String> input = Arrays.asList("Capital", "lower", "Foo", "bar");
Collector<String, ?, Map<Boolean, Optional<Integer>>> collector =
MoreCollectors.partitioningBy(
str -> Character.isUpperCase(str.charAt(0)),
MoreCollectors.mapping(String::length, MoreCollectors.first()));
checkShortCircuitCollector(
"mapping", new BooleanMap<>(Optional.of(7), Optional.of(5)), 2, input::stream, collector);
Collector<String, ?, Map<Boolean, Optional<Integer>>> collectorLast =
MoreCollectors.partitioningBy(
str -> Character.isUpperCase(str.charAt(0)),
MoreCollectors.mapping(String::length, MoreCollectors.last()));
checkCollector(
"last", new BooleanMap<>(Optional.of(3), Optional.of(3)), input::stream, collectorLast);
input = Arrays.asList("Abc", "Bac", "Aac", "Abv", "Bbc", "Bgd", "Atc", "Bpv");
Map<Character, List<String>> expected =
EntryStream.of('A', Arrays.asList("Abc", "Aac"), 'B', Arrays.asList("Bac", "Bbc")).toMap();
AtomicInteger cnt = new AtomicInteger();
Collector<String, ?, Map<Character, List<String>>> groupMap =
Collectors.groupingBy(
s -> s.charAt(0),
MoreCollectors.mapping(
x -> {
cnt.incrementAndGet();
return x;
},
MoreCollectors.head(2)));
checkCollector("groupMap", expected, input::stream, groupMap);
cnt.set(0);
assertEquals(expected, input.stream().collect(groupMap));
assertEquals(4, cnt.get());
}