[Java 12편] Map Sort 정리

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[Java 12편] Map Sort 정리

Java Map Sort 정리

• Java Map Sort 관련 예제를 작성했습니다.

Source

	class MapSortTest {
	@Test
	@DisplayName("String type value 로 map sort")
	void testMapSortStringValueTest() {
	final Map<Integer, String> map = Map.of(
	10, "abc",
	5, "def",
	2, "adef"
	);
	final Map<Integer, String> sortedMap =
	map.entrySet()
	.stream()
	.sorted(Map.Entry.comparingByValue())
	.collect(Collectors.toMap(
	Map.Entry::getKey,
	Map.Entry::getValue,
	(oldValue, newValue) -> oldValue,
	LinkedHashMap::new)
	);
	Assertions.assertEquals(Map.of(10, "abc", 2, "adef", 5, "def"), sortedMap);
	}
	@Test
	@DisplayName("String type value 로 map reverse sort")
	void testMapReverseSortStringValueTest() {
	final Map<Integer, String> map = Map.of(
	10, "abc",
	5, "def",
	2, "adef"
	);
	final Map<Integer, String> sortedMap =
	map.entrySet()
	.stream()
	.sorted(Map.Entry.comparingByValue(Comparator.reverseOrder()))
	.collect(Collectors.toMap(
	Map.Entry::getKey,
	Map.Entry::getValue,
	(oldValue, newValue) -> oldValue,
	LinkedHashMap::new)
	);
	Assertions.assertEquals(
	Map.of(
	5, "def",
	2, "adef",
	10, "abc"
	),
	sortedMap
	);
	}
	@Test
	@DisplayName("Object value 로 Map sort")
	void testMapSortObjectValueTest() {
	final Map<Integer, Value> map =
	Map.of(3, Value.builder()
	.id("123")
	.name("test3")
	.build(),
	2, Value.builder()
	.id("234")
	.name("test2")
	.build(),
	1, Value.builder()
	.id("345")
	.name("test1")
	.build()
	);
	final Map<Integer, Value> sortedMap =
	map.entrySet()
	.stream()
	.sorted(Entry.comparingByValue(Comparator.comparing(Value::getName)))
	.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue,
	(oldValue, newValue) -> oldValue, LinkedHashMap::new));
	Assertions.assertEquals(
	Map.of(
	1, Value.builder()
	.id("345")
	.name("test1")
	.build(),
	2, Value.builder()
	.id("234")
	.name("test2")
	.build(),
	3, Value.builder()
	.id("123")
	.name("test3")
	.build()
	),
	sortedMap
	);
	}
	@Test
	@DisplayName("Object value CustomComparator Map sort")
	void testMapSortObjectValueCustomComparatorTest() {
	final Map<Integer, Value> map =
	Map.of(3, Value.builder()
	.id("123")
	.name("test3")
	.build(),
	2, Value.builder()
	.id("234")
	.name("test2")
	.build(),
	1, Value.builder()
	.id("345")
	.name("test1")
	.build()
	);
	final Map<Integer, Value> sortedMap =
	map.entrySet()
	.stream()
	.sorted(Comparator.comparing(e -> CustomComparator.getValueOrder(e.getValue().name)))
	.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue,
	(oldValue, newValue) -> oldValue, LinkedHashMap::new));
	Assertions.assertEquals(
	Map.of(
	1, Value.builder()
	.id("345")
	.name("test1")
	.build(),
	2, Value.builder()
	.id("234")
	.name("test2")
	.build(),
	3, Value.builder()
	.id("123")
	.name("test3")
	.build()
	),
	sortedMap
	);
	}
	@Data
	@Builder
	@AllArgsConstructor
	public static class Value {
	private String id;
	private String name;
	}
	public static class CustomComparator {
	private static final Map<String, Integer> valueOrderMap =
	Map.of(
	"test1", 1,
	"test2", 2,
	"test3", 3
	);
	public static Integer getValueOrder(final String value) {
	return valueOrderMap.get(value);
	}
	}
	}

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