@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 testPartitioningBy() {
Collector<Integer, ?, Map<Boolean, Optional<Integer>>> by20 =
MoreCollectors.partitioningBy(x -> x % 20 == 0, MoreCollectors.first());
Collector<Integer, ?, Map<Boolean, Optional<Integer>>> by200 =
MoreCollectors.partitioningBy(x -> x % 200 == 0, MoreCollectors.first());
Supplier<Stream<Integer>> supplier = () -> IntStreamEx.range(1, 100).boxed();
checkShortCircuitCollector(
"by20", new BooleanMap<>(Optional.of(20), Optional.of(1)), 20, supplier, by20);
checkShortCircuitCollector(
"by200", new BooleanMap<>(Optional.empty(), Optional.of(1)), 99, supplier, by200);
}
@Test
public void testFiltering() {
Collector<Integer, ?, Optional<Integer>> firstEven =
MoreCollectors.filtering(x -> x % 2 == 0, MoreCollectors.first());
Collector<Integer, ?, Optional<Integer>> firstOdd =
MoreCollectors.filtering(x -> x % 2 != 0, MoreCollectors.first());
Collector<Integer, ?, Integer> sumOddEven =
MoreCollectors.pairing(firstEven, firstOdd, (e, o) -> e.get() + o.get());
List<Integer> ints = Arrays.asList(1, 3, 5, 7, 9, 10, 8, 6, 4, 2, 3, 7, 11);
checkShortCircuitCollector("sumOddEven", 11, 6, ints::stream, sumOddEven);
Collector<Integer, ?, Long> countEven =
MoreCollectors.filtering(x -> x % 2 == 0, Collectors.counting());
checkCollector("filtering", 5L, ints::stream, countEven);
}
@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());
}
@Test
public void testGroupingByWithDomain() {
List<String> data = Arrays.asList("a", "foo", "test", "ququq", "bar", "blahblah");
Collector<String, ?, String> collector =
MoreCollectors.collectingAndThen(
MoreCollectors.groupingBy(
String::length,
IntStreamEx.range(10).boxed().toSet(),
TreeMap::new,
MoreCollectors.first()),
Object::toString);
checkShortCircuitCollector(
"groupingWithDomain",
"{0=Optional.empty, 1=Optional[a], 2=Optional.empty, 3=Optional[foo], 4=Optional[test], 5=Optional[ququq], "
+ "6=Optional.empty, 7=Optional.empty, 8=Optional[blahblah], 9=Optional.empty}",
data.size(),
data::stream,
collector);
Map<String, String> name2sex = new LinkedHashMap<>();
name2sex.put("Mary", "Girl");
name2sex.put("John", "Boy");
name2sex.put("James", "Boy");
name2sex.put("Lucie", "Girl");
name2sex.put("Fred", "Boy");
name2sex.put("Thomas", "Boy");
name2sex.put("Jane", "Girl");
name2sex.put("Ruth", "Girl");
name2sex.put("Melanie", "Girl");
Collector<Entry<String, String>, ?, Map<String, List<String>>> groupingBy =
MoreCollectors.groupingBy(
Entry::getValue,
StreamEx.of("Girl", "Boy").toSet(),
MoreCollectors.mapping(Entry::getKey, MoreCollectors.head(2)));
AtomicInteger counter = new AtomicInteger();
Map<String, List<String>> map =
EntryStream.of(name2sex).peek(c -> counter.incrementAndGet()).collect(groupingBy);
assertEquals(Arrays.asList("Mary", "Lucie"), map.get("Girl"));
assertEquals(Arrays.asList("John", "James"), map.get("Boy"));
assertEquals(4, counter.get());
Collector<Entry<String, String>, ?, Map<String, String>> groupingByJoin =
MoreCollectors.groupingBy(
Entry::getValue,
StreamEx.of("Girl", "Boy").toSet(),
MoreCollectors.mapping(
Entry::getKey, Joining.with(", ").maxChars(16).cutAfterDelimiter()));
counter.set(0);
Map<String, String> mapJoin =
EntryStream.of(name2sex).peek(c -> counter.incrementAndGet()).collect(groupingByJoin);
assertEquals("Mary, Lucie, ...", mapJoin.get("Girl"));
assertEquals("John, James, ...", mapJoin.get("Boy"));
assertEquals(7, counter.get());
}
@Test
public void testMaxAll() {
List<String> input = Arrays.asList("a", "bb", "c", "", "cc", "eee", "bb", "ddd");
checkCollector(
"maxAll",
Arrays.asList("eee", "ddd"),
input::stream,
MoreCollectors.maxAll(Comparator.comparingInt(String::length)));
Collector<String, ?, String> maxAllJoin =
MoreCollectors.maxAll(Comparator.comparingInt(String::length), Collectors.joining(","));
checkCollector("maxAllJoin", "eee,ddd", input::stream, maxAllJoin);
checkCollector(
"minAll",
1L,
input::stream,
MoreCollectors.minAll(Comparator.comparingInt(String::length), Collectors.counting()));
checkCollector(
"minAllEmpty",
Arrays.asList(""),
input::stream,
MoreCollectors.minAll(Comparator.comparingInt(String::length)));
checkCollectorEmpty(
"maxAll",
Collections.emptyList(),
MoreCollectors.maxAll(Comparator.comparingInt(String::length)));
checkCollectorEmpty("maxAllJoin", "", maxAllJoin);
List<Integer> ints = IntStreamEx.of(new Random(1), 10000, 1, 1000).boxed().toList();
List<Integer> expectedMax = getMaxAll(ints, Comparator.naturalOrder());
List<Integer> expectedMin = getMaxAll(ints, Comparator.reverseOrder());
Collector<Integer, ?, SimpleEntry<Integer, Long>> downstream =
MoreCollectors.pairing(
MoreCollectors.first(),
Collectors.counting(),
(opt, cnt) -> new AbstractMap.SimpleEntry<>(opt.get(), cnt));
checkCollector("maxAll", expectedMax, ints::stream, MoreCollectors.maxAll(Integer::compare));
checkCollector("minAll", expectedMin, ints::stream, MoreCollectors.minAll());
checkCollector(
"entry",
new SimpleEntry<>(expectedMax.get(0), (long) expectedMax.size()),
ints::stream,
MoreCollectors.maxAll(downstream));
checkCollector(
"entry",
new SimpleEntry<>(expectedMin.get(0), (long) expectedMin.size()),
ints::stream,
MoreCollectors.minAll(downstream));
Integer a = new Integer(1), b = new Integer(1), c = new Integer(1000), d = new Integer(1000);
ints = IntStreamEx.range(10, 100).boxed().append(a, c).prepend(b, d).toList();
for (StreamExSupplier<Integer> supplier : streamEx(ints::stream)) {
List<Integer> list = supplier.get().collect(MoreCollectors.maxAll());
assertEquals(2, list.size());
assertSame(d, list.get(0));
assertSame(c, list.get(1));
list = supplier.get().collect(MoreCollectors.minAll());
assertEquals(2, list.size());
assertSame(b, list.get(0));
assertSame(a, list.get(1));
}
}
