[Java/자바] Stream 변환 표

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Stream ➡ 기본형 Stream

From	To	변환 메서드
Stream<T>	IntStream LongStream DoubleStream	mapToInt(ToIntFunction<T> mapper) MapToLong(ToLongFunction<T> mapper) MapToDouble(ToDoubleFunction<T> mapper)

 

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기본형 Stream ➡ Stream

From	To	변환 메서드
IntStream LongStream DoubleStream	Stream<Integer> Stream<Long> Stream<Double>	boxed()
	Stream<T>	mapToObj(DoubleFunction<T> mapper)

 

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기본형 Stream ➡ 기본형 Stream

From	To	변환 메서드
IntStream LongStream DoubleStream	LongStream DoubleStream	asLongStream() asDoubleStream()

 

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Stream ➡ 부분 Stream

From	To	변환 메서드
Stream<T> IntStream	Stream IntStream	skip(long n) limit(long maxSize)

 

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두 개의 Stream ➡ Stream

From	To	변환 메서드
Stream<T>, Stream<T>	Stream<T>	concat(Stream<T> a, Stream<T> b)
IntStream, IntStream	IntStream	concat(IntStream a, IntStream b)
LongStream, LongStream	LongStream	concat(LongStream a, LongStream b)
DoubleStream, DoubleStream	DoubleStream	concat(DoubleStream a, DoubleStream b)

 

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Stream의 Stream ➡ Stream

From	To	변환 메서드
Stream<Stream<T>>	Stream<T>	flatMap(Function mapper)
Stream<IntStream>	IntStream	flatMapToInt(Function mapper)
Stream<LongStream>	LongStream	flatMapToLong(Function mapper)
Stream<DoubleStream>	DoubleStream	flatMapToDouble(Function mapper)

 

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Stream ➡ 병렬 Stream

From	To	변환 메서드
Stream<T> IntStream LongStream DoubleStream	Stream<T> IntStream LongStream DoubleStream	parallel() // 스트림 -> 병렬 스트림 sequential // 병렬 스트림 -> 스트림

 

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Stream ➡ Collection

From	To	변환 메서드
Stream<T> IntStream LongStream DoubleStream	Collection<T>	collect(Collectors.toCollection(Supplierfactory)
	List<T>	collect(Collectors.toList())
	Set<T>	collect(Collectors.toSet())

 

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Collection ➡ Stream

From	To	변환 메서드
Collection<T>, List<T>, Set<T>	Stream<T>	stream()

 

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Stream ➡ Map

From	To	변환 메서드
Stream<T> IntStream LongStream DoubleStream	Map<K, V>	collect(Collectors.toMap(Function key, Function value) collect(Collectors.toMap(Function key, Function value, BinaryOperator) collect(Collectors.toMap(Function key, Function value, BinaryOperator merge, Supplier mapSupplier)

 

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Stream ➡ 배열

From	To	변환 메서드
Stream<T>	Object[]	toArray()
	T[]	toArray(IntFunction<A[] generator)
IntStream LongStream DoubleStream	int[] long[] double[]	toArray()