@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());
}