Package io.vavr.collection

Interface Stream<T>

Type Parameters:

T - component type of this Stream

All Superinterfaces:

Foldable<T>, Function<Integer,T>, Function1<Integer,T>, Iterable<T>, LinearSeq<T>, PartialFunction<Integer,T>, Seq<T>, Serializable, Traversable<T>, Value<T>

All Known Implementing Classes:

Stream.Cons, Stream.Empty

public interface Stream<T>
extends LinearSeq<T>

An immutable Stream is lazy sequence of elements which may be infinitely long. Its immutability makes it suitable for concurrent programming.

A Stream is composed of a head element and a lazy evaluated tail Stream.

There are two implementations of the Stream interface:

• Stream.Empty, which represents the empty Stream.
• Stream.Cons, which represents a Stream containing one or more elements.

Methods to obtain a Stream:

 
 // factory methods
 Stream.empty()                  // = Stream.of() = Nil.instance()
 Stream.of(x)                    // = new Cons<>(x, Nil.instance())
 Stream.of(Object...)            // e.g. Stream.of(1, 2, 3)
 Stream.ofAll(Iterable)          // e.g. Stream.ofAll(List.of(1, 2, 3)) = 1, 2, 3
 Stream.ofAll(<primitive array>) // e.g. List.ofAll(1, 2, 3) = 1, 2, 3

 // int sequences
 Stream.from(0)                  // = 0, 1, 2, 3, ...
 Stream.range(0, 3)              // = 0, 1, 2
 Stream.rangeClosed(0, 3)        // = 0, 1, 2, 3

 // generators
 Stream.cons(Object, Supplier)   // e.g. Stream.cons(current, () -> next(current));
 Stream.continually(Supplier)    // e.g. Stream.continually(Math::random);
 Stream.iterate(Object, Function)// e.g. Stream.iterate(1, i -> i * 2);
 
 

Factory method applications:

 
 Stream<Integer>       s1 = Stream.of(1);
 Stream<Integer>       s2 = Stream.of(1, 2, 3);
                       // = Stream.of(new Integer[] {1, 2, 3});

 Stream<int[]>         s3 = Stream.ofAll(1, 2, 3);
 Stream<List<Integer>> s4 = Stream.ofAll(List.of(1, 2, 3));

 Stream<Integer>       s5 = Stream.ofAll(1, 2, 3);
 Stream<Integer>       s6 = Stream.ofAll(List.of(1, 2, 3));

 // cuckoo's egg
 Stream<Integer[]>     s7 = Stream.<Integer[]> of(new Integer[] {1, 2, 3});
 
 

Example: Generating prime numbers

 
 // = Stream(2L, 3L, 5L, 7L, ...)
 Stream.iterate(2L, PrimeNumbers::nextPrimeFrom)

 // helpers

 static long nextPrimeFrom(long num) {
     return Stream.from(num + 1).find(PrimeNumbers::isPrime).get();
 }

 static boolean isPrime(long num) {
     return !Stream.rangeClosed(2L, (long) Math.sqrt(num)).exists(d -> num % d == 0);
 }
 
 

See Okasaki, Chris: Purely Functional Data Structures (p. 34 ff.). Cambridge, 2003.

Author:

Daniel Dietrich, Jörgen Andersson, Ruslan Sennov

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	Stream.Cons<T>	Non-empty Stream, consisting of a head, and tail.
static final class	Stream.Empty<T>	The empty Stream.

Field Summary

Fields

Modifier and Type	Field	Description
static final long	serialVersionUID

Method Summary

Modifier and Type	Method	Description
default Stream<T>	append(T element)	Appends an element to this.
default Stream<T>	appendAll(Iterable<? extends T> elements)	Appends all given elements to this.
default Stream<T>	appendSelf(Function<? super Stream<T>,? extends Stream<T>> mapper)	Appends itself to the end of stream with mapper function.
default List<T>	asJava()	Creates an immutable List view on top of this Seq, i.e. calling mutators will result in UnsupportedOperationException at runtime.
default Stream<T>	asJava(Consumer<? super List<T>> action)	Creates an immutable List view on top of this Seq that is passed to the given action.
default List<T>	asJavaMutable()	Creates a mutable List view on top of this Seq, i.e. all mutator methods of the List are implemented.
default Stream<T>	asJavaMutable(Consumer<? super List<T>> action)	Creates a mutable List view on top of this Seq that is passed to the given action.
default <R> Stream<R>	collect(PartialFunction<? super T,? extends R> partialFunction)	Collects all elements that are in the domain of the given partialFunction by mapping the elements to type R.
static <T> Collector<T,ArrayList<T>,Stream<T>>	collector()	Returns a Collector which may be used in conjunction with Stream.collect(java.util.stream.Collector) to obtain a Stream.
default Stream<Stream<T>>	combinations()	Returns the union of all combinations from k = 0 to length().
default Stream<Stream<T>>	combinations(int k)	Returns the k-combination of this traversable, i.e. all subset of this of k distinct elements.
static <T> Stream<T>	concat(Iterable<? extends Iterable<? extends T>> iterables)	Lazily creates a Stream in O(1) which traverses along the concatenation of the given iterables.
static <T> Stream<T>	concat(Iterable<? extends T>... iterables)	Lazily creates a Stream in O(1) which traverses along the concatenation of the given iterables.
static <T> Stream<T>	cons(T head, Supplier<? extends Stream<? extends T>> tailSupplier)	Constructs a Stream of a head element and a tail supplier.
static <T> Stream<T>	continually(Supplier<? extends T> supplier)	Generates an (theoretically) infinitely long Stream using a value Supplier.
static <T> Stream<T>	continually(T t)	Repeats an element infinitely often.
default Iterator<Stream<T>>	crossProduct(int power)	Calculates the n-ary cartesian power (or cross product or simply product) of this.
default Stream<T>	cycle()	Repeat the elements of this Stream infinitely.
default Stream<T>	cycle(int count)	Repeat the elements of this Stream count times.
default Stream<T>	distinct()	Returns a new version of this which contains no duplicates.
default Stream<T>	distinctBy(Comparator<? super T> comparator)	Returns a new version of this which contains no duplicates.
default <U> Stream<T>	distinctBy(Function<? super T,? extends U> keyExtractor)	Returns a new version of this which contains no duplicates.
default Stream<T>	drop(int n)	Drops the first n elements of this or all elements, if this length < n.
default Stream<T>	dropRight(int n)	Drops the last n elements of this or all elements, if this length < n.
default Stream<T>	dropRightUntil(Predicate<? super T> predicate)	Drops elements until the predicate holds for the current element, starting from the end.
default Stream<T>	dropRightWhile(Predicate<? super T> predicate)	Drops elements while the predicate holds for the current element, starting from the end.
default Stream<T>	dropUntil(Predicate<? super T> predicate)	Drops elements until the predicate holds for the current element.
default Stream<T>	dropWhile(Predicate<? super T> predicate)	Drops elements while the predicate holds for the current element.
static <T> Stream<T>	empty()	Returns the single instance of Nil.
default Stream<T>	extend(Function<? super T,? extends T> nextFunction)	Extends (continues) this Stream with a Stream of values created by applying consecutively provided Function to the last element of the original Stream.
default Stream<T>	extend(Supplier<? extends T> nextSupplier)	Extends (continues) this Stream with values provided by a Supplier
default Stream<T>	extend(T next)	Extends (continues) this Stream with a constantly repeated value.
static <T> Stream<T>	fill(int n, Supplier<? extends T> s)	Returns a Stream containing n values supplied by a given Supplier s.
static <T> Stream<T>	fill(int n, T element)	Returns a Stream containing n times the given element
default Stream<T>	filter(Predicate<? super T> predicate)	Returns a new traversable consisting of all elements which satisfy the given predicate.
default <U> Stream<U>	flatMap(Function<? super T,? extends Iterable<? extends U>> mapper)	FlatMaps this Traversable.
static Stream<Integer>	from(int value)	Returns an infinitely long Stream of int values starting from from.
static Stream<Integer>	from(int value, int step)	Returns an infinite long Stream of int values starting from value and spaced by step.
static Stream<Long>	from(long value)	Returns an infinitely long Stream of long values starting from from.
static Stream<Long>	from(long value, long step)	Returns an infinite long Stream of long values starting from value and spaced by step.
default T	get(int index)	Returns the element at the specified index.
default <C> Map<C,Stream<T>>	groupBy(Function<? super T,? extends C> classifier)	Groups this elements by classifying the elements.
default Iterator<Stream<T>>	grouped(int size)	Groups this Traversable into fixed size blocks.
default boolean	hasDefiniteSize()	Checks if this Traversable is known to have a finite size.
default int	indexOf(T element, int from)	Returns the index of the first occurrence of the given element after or at some start index or -1 if this does not contain the given element.
default Stream<T>	init()	Dual of Traversable.tail(), returning all elements except the last.
default Option<Stream<T>>	initOption()	Dual of Traversable.tailOption(), returning all elements except the last as Option.
default Stream<T>	insert(int index, T element)	Inserts the given element at the specified index.
default Stream<T>	insertAll(int index, Iterable<? extends T> elements)	Inserts the given elements at the specified index.
default Stream<T>	intersperse(T element)	Inserts an element between all elements of this Traversable.
default boolean	isAsync()	A Stream is computed synchronously.
default boolean	isLazy()	A Stream is computed lazily.
default boolean	isTraversableAgain()	Checks if this Traversable can be repeatedly traversed.
static <T> Stream<T>	iterate(Supplier<? extends Option<? extends T>> supplier)	Generates a (theoretically) infinitely long Stream using a repeatedly invoked supplier that provides a Some for each next value and a None for the end.
static <T> Stream<T>	iterate(T seed, Function<? super T,? extends T> f)	Generates a (theoretically) infinitely long Stream using a function to calculate the next value based on the previous.
default T	last()	Dual of Traversable.head(), returning the last element.
default int	lastIndexOf(T element, int end)	Returns the index of the last occurrence of the given element before or at a given end index or -1 if this does not contain the given element.
default Stream<T>	leftPadTo(int length, T element)	A copy of this sequence with an element prepended until a given target length is reached.
default int	length()	Computes the number of elements of this Traversable.
default <U> Stream<U>	map(Function<? super T,? extends U> mapper)	Maps the elements of this Traversable to elements of a new type preserving their order, if any.
static <T> Stream<T>	narrow(Stream<? extends T> stream)	Narrows a widened Stream<? extends T> to Stream<T> by performing a type-safe cast.
static <T> Stream<T>	of(T element)	Returns a singleton Stream, i.e. a Stream of one element.
static <T> Stream<T>	of(T... elements)	Creates a Stream of the given elements.
static Stream<Boolean>	ofAll(boolean... elements)	Creates a Stream from boolean values.
static Stream<Byte>	ofAll(byte... elements)	Creates a Stream from byte values.
static Stream<Character>	ofAll(char... elements)	Creates a Stream from char values.
static Stream<Double>	ofAll(double... elements)	Creates a Stream values double values.
static Stream<Float>	ofAll(float... elements)	Creates a Stream from float values.
static Stream<Integer>	ofAll(int... elements)	Creates a Stream from int values.
static Stream<Long>	ofAll(long... elements)	Creates a Stream from long values.
static Stream<Short>	ofAll(short... elements)	Creates a Stream from short values.
static <T> Stream<T>	ofAll(Iterable<? extends T> elements)	Creates a Stream of the given elements.
static <T> Stream<T>	ofAll(Stream<? extends T> javaStream)	Creates a Stream that contains the elements of the given Stream.
default Stream<T>	orElse(Iterable<? extends T> other)	Returns this Traversable if it is nonempty, otherwise return the alternative.
default Stream<T>	orElse(Supplier<? extends Iterable<? extends T>> supplier)	Returns this Traversable if it is nonempty, otherwise return the result of evaluating supplier.
default Stream<T>	padTo(int length, T element)	A copy of this sequence with an element appended until a given target length is reached.
default Tuple2<Stream<T>,Stream<T>>	partition(Predicate<? super T> predicate)	Creates a partition of this Traversable by splitting this elements in two in distinct traversables according to a predicate.
default Stream<T>	patch(int from, Iterable<? extends T> that, int replaced)	Produces a new list where a slice of elements in this list is replaced by another sequence.
default Stream<T>	peek(Consumer<? super T> action)	Performs the given action on the first element if this is an eager implementation.
default Stream<Stream<T>>	permutations()	Computes all unique permutations.
default Stream<T>	prepend(T element)	Prepends an element to this.
default Stream<T>	prependAll(Iterable<? extends T> elements)	Prepends all given elements to this.
static Stream<Character>	range(char from, char toExclusive)
static Stream<Integer>	range(int from, int toExclusive)	Creates a Stream of int numbers starting from from, extending to toExclusive - 1.
static Stream<Long>	range(long from, long toExclusive)	Creates a Stream of long numbers starting from from, extending to toExclusive - 1.
static Stream<Character>	rangeBy(char from, char toExclusive, int step)
static Stream<Double>	rangeBy(double from, double toExclusive, double step)
static Stream<Integer>	rangeBy(int from, int toExclusive, int step)	Creates a Stream of int numbers starting from from, extending to toExclusive - 1, with step.
static Stream<Long>	rangeBy(long from, long toExclusive, long step)	Creates a Stream of long numbers starting from from, extending to toExclusive - 1, with step.
static Stream<Character>	rangeClosed(char from, char toInclusive)
static Stream<Integer>	rangeClosed(int from, int toInclusive)	Creates a Stream of int numbers starting from from, extending to toInclusive.
static Stream<Long>	rangeClosed(long from, long toInclusive)	Creates a Stream of long numbers starting from from, extending to toInclusive.
static Stream<Character>	rangeClosedBy(char from, char toInclusive, int step)
static Stream<Double>	rangeClosedBy(double from, double toInclusive, double step)
static Stream<Integer>	rangeClosedBy(int from, int toInclusive, int step)	Creates a Stream of int numbers starting from from, extending to toInclusive, with step.
static Stream<Long>	rangeClosedBy(long from, long toInclusive, long step)	Creates a Stream of long numbers starting from from, extending to toInclusive, with step.
default Stream<T>	reject(Predicate<? super T> predicate)	Returns a new traversable consisting of all elements which do not satisfy the given predicate.
default Stream<T>	remove(T element)	Removes the first occurrence of the given element.
default Stream<T>	removeAll(Iterable<? extends T> elements)	Removes all occurrences of the given elements.
default Stream<T>	removeAll(Predicate<? super T> predicate)	Deprecated.
default Stream<T>	removeAll(T element)	Removes all occurrences of the given element.
default Stream<T>	removeAt(int index)	Removes the element at the specified position in this sequence.
default Stream<T>	removeFirst(Predicate<T> predicate)	Removes the first occurrence that satisfy predicate
default Stream<T>	removeLast(Predicate<T> predicate)	Removes the last occurrence that satisfy predicate
default Stream<T>	replace(T currentElement, T newElement)	Replaces the first occurrence (if exists) of the given currentElement with newElement.
default Stream<T>	replaceAll(T currentElement, T newElement)	Replaces all occurrences of the given currentElement with newElement.
default Stream<T>	retainAll(Iterable<? extends T> elements)	Keeps all occurrences of the given elements from this.
default Stream<T>	reverse()	Reverses the order of elements.
default Stream<T>	rotateLeft(int n)	Circular rotates the elements by the specified distance to the left direction.
default Stream<T>	rotateRight(int n)	Circular rotates the elements by the specified distance to the right direction.
default Stream<T>	scan(T zero, BiFunction<? super T,? super T,? extends T> operation)	Computes a prefix scan of the elements of the collection.
default <U> Stream<U>	scanLeft(U zero, BiFunction<? super U,? super T,? extends U> operation)	Produces a collection containing cumulative results of applying the operator going left to right.
default <U> Stream<U>	scanRight(U zero, BiFunction<? super T,? super U,? extends U> operation)	Produces a collection containing cumulative results of applying the operator going right to left.
default Stream<T>	shuffle()	Randomize the order of the elements in the current sequence.
default Stream<T>	slice(int beginIndex, int endIndex)	Returns a Seq that is a slice of this.
default Iterator<Stream<T>>	slideBy(Function<? super T,?> classifier)	Slides a non-overlapping window of a variable size over this Traversable.
default Iterator<Stream<T>>	sliding(int size)	Slides a window of a specific size and step size 1 over this Traversable by calling Traversable.sliding(int, int).
default Iterator<Stream<T>>	sliding(int size, int step)	Slides a window of a specific size and step size over this Traversable.
default <U> Stream<T>	sortBy(Comparator<? super U> comparator, Function<? super T,? extends U> mapper)	Sorts this elements by comparing the elements in a different domain, using the given mapper.
default <U extends Comparable<? super U>> Stream<T>	sortBy(Function<? super T,? extends U> mapper)	Sorts this elements by comparing the elements in a different domain, using the given mapper.
default Stream<T>	sorted()	Sorts this elements according to their natural order.
default Stream<T>	sorted(Comparator<? super T> comparator)	Sorts this elements according to the provided Comparator.
default Tuple2<Stream<T>,Stream<T>>	span(Predicate<? super T> predicate)	Returns a tuple where the first element is the longest prefix of elements that satisfy the given predicate and the second element is the remainder.
default Tuple2<Stream<T>,Stream<T>>	splitAt(int n)	Splits a Seq at the specified index.
default Tuple2<Stream<T>,Stream<T>>	splitAt(Predicate<? super T> predicate)	Splits a sequence at the first element which satisfies the Predicate, e.g.
default Tuple2<Stream<T>,Stream<T>>	splitAtInclusive(Predicate<? super T> predicate)	Splits a sequence at the first element which satisfies the Predicate, e.g.
default String	stringPrefix()	Returns the name of this Value type, which is used by toString().
default Stream<T>	subSequence(int beginIndex)	Returns a Seq that is a subsequence of this.
default Stream<T>	subSequence(int beginIndex, int endIndex)	Returns a Seq that is a subsequence of this.
static <T> Stream<T>	tabulate(int n, Function<? super Integer,? extends T> f)	Returns a Stream containing n values of a given Function f over a range of integer values from 0 to n - 1.
Stream<T>	tail()	Drops the first element of a non-empty Traversable.
default Option<Stream<T>>	tailOption()	Drops the first element of a non-empty Traversable and returns an Option.
default Stream<T>	take(int n)	Takes the first n elements of this or all elements, if this length < n.
default Stream<T>	takeRight(int n)	Takes the last n elements of this or all elements, if this length < n.
default Stream<T>	takeRightUntil(Predicate<? super T> predicate)	Takes elements until the predicate holds for the current element, starting from the end.
default Stream<T>	takeRightWhile(Predicate<? super T> predicate)	Takes elements while the predicate holds for the current element, starting from the end.
default Stream<T>	takeUntil(Predicate<? super T> predicate)	Takes elements until the predicate holds for the current element.
default Stream<T>	takeWhile(Predicate<? super T> predicate)	Takes elements while the predicate holds for the current element.
default <U> U	transform(Function<? super Stream<T>,? extends U> f)	Transforms this Stream.
static <T> Stream<Stream<T>>	transpose(Stream<Stream<T>> matrix)	Transposes the rows and columns of a Stream matrix.
static <T> Stream<T>	unfold(T seed, Function<? super T,Option<Tuple2<? extends T,? extends T>>> f)	Creates a Stream from a seed value and a function.
static <T, U> Stream<U>	unfoldLeft(T seed, Function<? super T,Option<Tuple2<? extends T,? extends U>>> f)	Creates a Stream from a seed value and a function.
static <T, U> Stream<U>	unfoldRight(T seed, Function<? super T,Option<Tuple2<? extends U,? extends T>>> f)	Creates a Stream from a seed value and a function.
default <T1, T2> Tuple2<Stream<T1>,Stream<T2>>	unzip(Function<? super T,Tuple2<? extends T1,? extends T2>> unzipper)	Unzips this elements by mapping this elements to pairs which are subsequently split into two distinct sets.
default <T1, T2, T3> Tuple3<Stream<T1>,Stream<T2>,Stream<T3>>	unzip3(Function<? super T,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)	Unzips this elements by mapping this elements to triples which are subsequently split into three distinct sets.
default Stream<T>	update(int index, Function<? super T,? extends T> updater)	Updates the given element at the specified index using the specified function.
default Stream<T>	update(int index, T element)	Updates the given element at the specified index.
default <U> Stream<Tuple2<T,U>>	zip(Iterable<? extends U> that)	Returns a traversable formed from this traversable and another Iterable collection by combining corresponding elements in pairs.
default <U> Stream<Tuple2<T,U>>	zipAll(Iterable<? extends U> iterable, T thisElem, U thatElem)	Returns a traversable formed from this traversable and another Iterable by combining corresponding elements in pairs.
default <U, R> Stream<R>	zipWith(Iterable<? extends U> that, BiFunction<? super T,? super U,? extends R> mapper)	Returns a traversable formed from this traversable and another Iterable collection by mapping elements.
default Stream<Tuple2<T,Integer>>	zipWithIndex()	Zips this traversable with its indices.
default <U> Stream<U>	zipWithIndex(BiFunction<? super T,? super Integer,? extends U> mapper)	Zips this traversable with its indices by applying mapper provided.

Methods inherited from interface io.vavr.collection.Foldable

fold, reduce, reduceOption

Methods inherited from interface io.vavr.Function1

andThen, arity, compose, curried, isMemoized, memoized, partial, reversed, tupled

Methods inherited from interface io.vavr.collection.LinearSeq

asPartialFunction, indexOfSlice, indexWhere, isDefinedAt, lastIndexOfSlice, lastIndexWhere, reverseIterator, search, search, segmentLength

Methods inherited from interface io.vavr.collection.Seq

apply, containsSlice, crossProduct, crossProduct, endsWith, foldRight, indexOf, indexOfOption, indexOfOption, indexOfSlice, indexOfSliceOption, indexOfSliceOption, indexWhere, indexWhereOption, indexWhereOption, isSequential, iterator, lastIndexOf, lastIndexOfOption, lastIndexOfOption, lastIndexOfSlice, lastIndexOfSliceOption, lastIndexOfSliceOption, lastIndexWhere, lastIndexWhereOption, lastIndexWhereOption, lift, prefixLength, startsWith, startsWith, withDefault, withDefaultValue

Methods inherited from interface io.vavr.collection.Traversable

arrangeBy, average, containsAll, count, equals, existsUnique, find, findLast, foldLeft, forEachWithIndex, get, hashCode, head, headOption, isDistinct, isEmpty, isOrdered, isSingleValued, iterator, lastOption, max, maxBy, maxBy, min, minBy, minBy, mkCharSeq, mkCharSeq, mkCharSeq, mkString, mkString, mkString, nonEmpty, product, reduceLeft, reduceLeftOption, reduceRight, reduceRightOption, single, singleOption, size, spliterator, sum

Methods inherited from interface io.vavr.Value

collect, collect, contains, corresponds, eq, exists, forAll, forEach, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, out, out, stderr, stdout, toArray, toCharSeq, toCompletableFuture, toEither, toEither, toInvalid, toInvalid, toJavaArray, toJavaArray, toJavaArray, toJavaCollection, toJavaList, toJavaList, toJavaMap, toJavaMap, toJavaMap, toJavaOptional, toJavaParallelStream, toJavaSet, toJavaSet, toJavaStream, toLeft, toLeft, toLinkedMap, toLinkedMap, toLinkedSet, toList, toMap, toMap, toOption, toPriorityQueue, toPriorityQueue, toQueue, toRight, toRight, toSet, toSortedMap, toSortedMap, toSortedMap, toSortedMap, toSortedSet, toSortedSet, toStream, toString, toTree, toTree, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

Field Details

serialVersionUID

static final long serialVersionUID

See Also:

• Constant Field Values

Method Details

collector

static <T> Collector<T,ArrayList<T>,Stream<T>> collector()

Returns a Collector which may be used in conjunction with Stream.collect(java.util.stream.Collector) to obtain a Stream.

Type Parameters:

T - Component type of the Stream.

Returns:

A io.vavr.collection.Stream Collector.

concat

@SafeVarargs
static <T> Stream<T> concat(Iterable<? extends T>... iterables)

Lazily creates a Stream in O(1) which traverses along the concatenation of the given iterables.

Type Parameters:

T - Component type.

Parameters:

iterables - The iterables

Returns:

A new Stream

concat

static <T> Stream<T> concat(Iterable<? extends Iterable<? extends T>> iterables)

Lazily creates a Stream in O(1) which traverses along the concatenation of the given iterables.

Type Parameters:

T - Component type.

Parameters:

iterables - The iterable of iterables

Returns:

A new Stream

from

static Stream<Integer> from(int value)

Returns an infinitely long Stream of int values starting from from.

The Stream extends to Integer.MIN_VALUE when passing Integer.MAX_VALUE.

Parameters:

value - a start int value

Returns:

a new Stream of int values starting from from

from

static Stream<Integer> from(int value,
 int step)

Returns an infinite long Stream of int values starting from value and spaced by step.

The Stream extends to Integer.MIN_VALUE when passing Integer.MAX_VALUE.

Parameters:

value - a start int value

step - the step by which to advance on each next value

Returns:

a new Stream of int values starting from from

from

static Stream<Long> from(long value)

Returns an infinitely long Stream of long values starting from from.

The Stream extends to Integer.MIN_VALUE when passing Long.MAX_VALUE.

Parameters:

value - a start long value

Returns:

a new Stream of long values starting from from

from

static Stream<Long> from(long value,
 long step)

Returns an infinite long Stream of long values starting from value and spaced by step.

The Stream extends to Long.MIN_VALUE when passing Long.MAX_VALUE.

Parameters:

value - a start long value

step - the step by which to advance on each next value

Returns:

a new Stream of long values starting from from

continually

static <T> Stream<T> continually(Supplier<? extends T> supplier)

Generates an (theoretically) infinitely long Stream using a value Supplier.

Type Parameters:

T - value type

Parameters:

supplier - A Supplier of Stream values

Returns:

A new Stream

iterate

static <T> Stream<T> iterate(T seed,
 Function<? super T,? extends T> f)

Generates a (theoretically) infinitely long Stream using a function to calculate the next value based on the previous.

Type Parameters:

T - value type

Parameters:

seed - The first value in the Stream

f - A function to calculate the next value based on the previous

Returns:

A new Stream

iterate

static <T> Stream<T> iterate(Supplier<? extends Option<? extends T>> supplier)

Generates a (theoretically) infinitely long Stream using a repeatedly invoked supplier that provides a Some for each next value and a None for the end. The Supplier will be invoked only that many times until it returns None, and repeated iteration over the stream will produce the same values in the same order, without any further invocations to the Supplier.

Type Parameters:

T - value type

Parameters:

supplier - A Supplier of iterator values

Returns:

A new Stream

cons

static <T> Stream<T> cons(T head,
 Supplier<? extends Stream<? extends T>> tailSupplier)

Constructs a Stream of a head element and a tail supplier.

Type Parameters:

T - value type

Parameters:

head - The head element of the Stream

tailSupplier - A supplier of the tail values. To end the stream, return empty().

Returns:

A new Stream

empty

static <T> Stream<T> empty()

Returns the single instance of Nil. Convenience method for Nil.instance().

Note: this method intentionally returns type Stream and not Nil. This comes handy when folding. If you explicitly need type Nil use Stream.Empty.instance().

Type Parameters:

T - Component type of Nil, determined by type inference in the particular context.

Returns:

The empty list.

narrow

static <T> Stream<T> narrow(Stream<? extends T> stream)

Narrows a widened Stream<? extends T> to Stream<T> by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.

Type Parameters:

T - Component type of the Stream.

Parameters:

stream - A Stream.

Returns:

the given stream instance as narrowed type Stream<T>.

of

static <T> Stream<T> of(T element)

Returns a singleton Stream, i.e. a Stream of one element.

Type Parameters:

T - The component type

Parameters:

element - An element.

Returns:

A new Stream instance containing the given element

of

@SafeVarargs
static <T> Stream<T> of(T... elements)

Creates a Stream of the given elements.

  Stream.of(1, 2, 3, 4)
 = Nil.instance().prepend(4).prepend(3).prepend(2).prepend(1)
 = new Cons(1, new Cons(2, new Cons(3, new Cons(4, Nil.instance()))))

Type Parameters:

T - Component type of the Stream.

Parameters:

elements - Zero or more elements.

Returns:

A list containing the given elements in the same order.

tabulate

static <T> Stream<T> tabulate(int n,
 Function<? super Integer,? extends T> f)

Returns a Stream containing n values of a given Function f over a range of integer values from 0 to n - 1.

Type Parameters:

T - Component type of the Stream

Parameters:

n - The number of elements in the Stream

f - The Function computing element values

Returns:

A Stream consisting of elements f(0),f(1), ..., f(n - 1)

Throws:

NullPointerException - if f is null

fill

static <T> Stream<T> fill(int n,
 Supplier<? extends T> s)

Returns a Stream containing n values supplied by a given Supplier s.

Type Parameters:

T - Component type of the Stream

Parameters:

n - The number of elements in the Stream

s - The Supplier computing element values

Returns:

A Stream of size n, where each element contains the result supplied by s.

Throws:

NullPointerException - if s is null

fill

static <T> Stream<T> fill(int n,
 T element)

Returns a Stream containing n times the given element

Type Parameters:

T - Component type of the Stream

Parameters:

n - The number of elements in the Stream

element - The element

Returns:

A Stream of size n, where each element is the given element.

ofAll

static <T> Stream<T> ofAll(Iterable<? extends T> elements)

Creates a Stream of the given elements.

Type Parameters:

T - Component type of the Stream.

Parameters:

elements - An Iterable of elements.

Returns:

A Stream containing the given elements in the same order.

ofAll

static <T> Stream<T> ofAll(Stream<? extends T> javaStream)

Creates a Stream that contains the elements of the given Stream.

Type Parameters:

T - Component type of the Stream.

Parameters:

javaStream - A Stream

Returns:

A Stream containing the given elements in the same order.

ofAll

static Stream<Boolean> ofAll(boolean... elements)

Creates a Stream from boolean values.

Parameters:

elements - boolean values

Returns:

A new Stream of Boolean values

Throws:

NullPointerException - if elements is null

ofAll

static Stream<Byte> ofAll(byte... elements)

Creates a Stream from byte values.

Parameters:

elements - byte values

Returns:

A new Stream of Byte values

Throws:

NullPointerException - if elements is null

ofAll

static Stream<Character> ofAll(char... elements)

Creates a Stream from char values.

Parameters:

elements - char values

Returns:

A new Stream of Character values

Throws:

NullPointerException - if elements is null

ofAll

static Stream<Double> ofAll(double... elements)

Creates a Stream values double values.

Parameters:

elements - double values

Returns:

A new Stream of Double values

Throws:

NullPointerException - if elements is null

ofAll

static Stream<Float> ofAll(float... elements)

Creates a Stream from float values.

Parameters:

elements - float values

Returns:

A new Stream of Float values

Throws:

NullPointerException - if elements is null

ofAll

static Stream<Integer> ofAll(int... elements)

Creates a Stream from int values.

Parameters:

elements - int values

Returns:

A new Stream of Integer values

Throws:

NullPointerException - if elements is null

ofAll

static Stream<Long> ofAll(long... elements)

Creates a Stream from long values.

Parameters:

elements - long values

Returns:

A new Stream of Long values

Throws:

NullPointerException - if elements is null

ofAll

static Stream<Short> ofAll(short... elements)

Creates a Stream from short values.

Parameters:

elements - short values

Returns:

A new Stream of Short values

Throws:

NullPointerException - if elements is null

range

static Stream<Character> range(char from,
 char toExclusive)

rangeBy

static Stream<Character> rangeBy(char from,
 char toExclusive,
 int step)

rangeBy

@GwtIncompatible
static Stream<Double> rangeBy(double from,
 double toExclusive,
 double step)

range

static Stream<Integer> range(int from,
 int toExclusive)

Creates a Stream of int numbers starting from from, extending to toExclusive - 1.

Examples:

 
 Stream.range(0, 0)  // = Stream()
 Stream.range(2, 0)  // = Stream()
 Stream.range(-2, 2) // = Stream(-2, -1, 0, 1)
 
 

Parameters:

from - the first number

toExclusive - the last number + 1

Returns:

a range of int values as specified or Nil if from >= toExclusive

rangeBy

static Stream<Integer> rangeBy(int from,
 int toExclusive,
 int step)

Creates a Stream of int numbers starting from from, extending to toExclusive - 1, with step.

Examples:

 
 Stream.rangeBy(1, 3, 1)  // = Stream(1, 2)
 Stream.rangeBy(1, 4, 2)  // = Stream(1, 3)
 Stream.rangeBy(4, 1, -2) // = Stream(4, 2)
 Stream.rangeBy(4, 1, 2)  // = Stream()
 
 

Parameters:

from - the first number

toExclusive - the last number + 1

step - the step

Returns:

a range of long values as specified or Nil if
from >= toInclusive and step > 0 or
from <= toInclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

range

static Stream<Long> range(long from,
 long toExclusive)

Creates a Stream of long numbers starting from from, extending to toExclusive - 1.

Examples:

 
 Stream.range(0L, 0L)  // = Stream()
 Stream.range(2L, 0L)  // = Stream()
 Stream.range(-2L, 2L) // = Stream(-2L, -1L, 0L, 1L)
 
 

Parameters:

from - the first number

toExclusive - the last number + 1

Returns:

a range of long values as specified or Nil if from >= toExclusive

rangeBy

static Stream<Long> rangeBy(long from,
 long toExclusive,
 long step)

Creates a Stream of long numbers starting from from, extending to toExclusive - 1, with step.

Examples:

 
 Stream.rangeBy(1L, 3L, 1L)  // = Stream(1L, 2L)
 Stream.rangeBy(1L, 4L, 2L)  // = Stream(1L, 3L)
 Stream.rangeBy(4L, 1L, -2L) // = Stream(4L, 2L)
 Stream.rangeBy(4L, 1L, 2L)  // = Stream()
 
 

Parameters:

from - the first number

toExclusive - the last number + 1

step - the step

Returns:

a range of long values as specified or Nil if
from >= toInclusive and step > 0 or
from <= toInclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

rangeClosed

static Stream<Character> rangeClosed(char from,
 char toInclusive)

rangeClosedBy

static Stream<Character> rangeClosedBy(char from,
 char toInclusive,
 int step)

rangeClosedBy

@GwtIncompatible
static Stream<Double> rangeClosedBy(double from,
 double toInclusive,
 double step)

rangeClosed

static Stream<Integer> rangeClosed(int from,
 int toInclusive)

Creates a Stream of int numbers starting from from, extending to toInclusive.

Examples:

 
 Stream.rangeClosed(0, 0)  // = Stream(0)
 Stream.rangeClosed(2, 0)  // = Stream()
 Stream.rangeClosed(-2, 2) // = Stream(-2, -1, 0, 1, 2)
 
 

Parameters:

from - the first number

toInclusive - the last number

Returns:

a range of int values as specified or Nil if from > toInclusive

rangeClosedBy

static Stream<Integer> rangeClosedBy(int from,
 int toInclusive,
 int step)

Creates a Stream of int numbers starting from from, extending to toInclusive, with step.

Examples:

 
 Stream.rangeClosedBy(1, 3, 1)  // = Stream(1, 2, 3)
 Stream.rangeClosedBy(1, 4, 2)  // = Stream(1, 3)
 Stream.rangeClosedBy(4, 1, -2) // = Stream(4, 2)
 Stream.rangeClosedBy(4, 1, 2)  // = Stream()
 
 

Parameters:

from - the first number

toInclusive - the last number

step - the step

Returns:

a range of int values as specified or Nil if
from > toInclusive and step > 0 or
from < toInclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

rangeClosed

static Stream<Long> rangeClosed(long from,
 long toInclusive)

Creates a Stream of long numbers starting from from, extending to toInclusive.

Examples:

 
 Stream.rangeClosed(0L, 0L)  // = Stream(0L)
 Stream.rangeClosed(2L, 0L)  // = Stream()
 Stream.rangeClosed(-2L, 2L) // = Stream(-2L, -1L, 0L, 1L, 2L)
 
 

Parameters:

from - the first number

toInclusive - the last number

Returns:

a range of long values as specified or Nil if from > toInclusive

rangeClosedBy

static Stream<Long> rangeClosedBy(long from,
 long toInclusive,
 long step)

Creates a Stream of long numbers starting from from, extending to toInclusive, with step.

Examples:

 
 Stream.rangeClosedBy(1L, 3L, 1L)  // = Stream(1L, 2L, 3L)
 Stream.rangeClosedBy(1L, 4L, 2L)  // = Stream(1L, 3L)
 Stream.rangeClosedBy(4L, 1L, -2L) // = Stream(4L, 2L)
 Stream.rangeClosedBy(4L, 1L, 2L)  // = Stream()
 
 

Parameters:

from - the first number

toInclusive - the last number

step - the step

Returns:

a range of int values as specified or Nil if
from > toInclusive and step > 0 or
from < toInclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

transpose

static <T> Stream<Stream<T>> transpose(Stream<Stream<T>> matrix)

Transposes the rows and columns of a Stream matrix.

Type Parameters:

T - matrix element type

Parameters:

matrix - to be transposed.

Returns:

a transposed Stream matrix.

Throws:

IllegalArgumentException - if the row lengths of matrix differ.

ex: Stream.transpose(Stream(Stream(1,2,3), Stream(4,5,6))) → Stream(Stream(1,4), Stream(2,5), Stream(3,6))

unfoldRight

static <T,
U> Stream<U> unfoldRight(T seed,
 Function<? super T,Option<Tuple2<? extends U,? extends T>>> f)

Creates a Stream from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating the Stream, otherwise Some Tuple of the element for the next call and the value to add to the resulting Stream.

Example:

 
 Stream.unfoldRight(10, x -> x == 0
             ? Option.none()
             : Option.of(new Tuple2<>(x, x-1)));
 // Stream(10, 9, 8, 7, 6, 5, 4, 3, 2, 1))
 
 

Type Parameters:

T - type of seeds

U - type of unfolded values

Parameters:

seed - the start value for the iteration

f - the function to get the next step of the iteration

Returns:

a Stream with the values built up by the iteration

Throws:

NullPointerException - if f is null

unfoldLeft

static <T,
U> Stream<U> unfoldLeft(T seed,
 Function<? super T,Option<Tuple2<? extends T,? extends U>>> f)

Creates a Stream from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating the Stream, otherwise Some Tuple of the value to add to the resulting Stream and the element for the next call.

Example:

 
 Stream.unfoldLeft(10, x -> x == 0
             ? Option.none()
             : Option.of(new Tuple2<>(x-1, x)));
 // Stream(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
 
 

Type Parameters:

T - type of seeds

U - type of unfolded values

Parameters:

seed - the start value for the iteration

f - the function to get the next step of the iteration

Returns:

a Stream with the values built up by the iteration

Throws:

NullPointerException - if f is null

unfold

static <T> Stream<T> unfold(T seed,
 Function<? super T,Option<Tuple2<? extends T,? extends T>>> f)

Creates a Stream from a seed value and a function. The function takes the seed at first. The function should return None when it's done generating the Stream, otherwise Some Tuple of the value to add to the resulting Stream and the element for the next call.

Example:

 
 Stream.unfold(10, x -> x == 0
             ? Option.none()
             : Option.of(new Tuple2<>(x-1, x)));
 // Stream(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
 
 

Type Parameters:

T - type of seeds and unfolded values

Parameters:

seed - the start value for the iteration

f - the function to get the next step of the iteration

Returns:

a Stream with the values built up by the iteration

Throws:

NullPointerException - if f is null

continually

static <T> Stream<T> continually(T t)

Repeats an element infinitely often.

Type Parameters:

T - Element type

Parameters:

t - An element

Returns:

A new Stream containing infinite t's.

append

default Stream<T> append(T element)

Description copied from interface: Seq

Appends an element to this.

Specified by:

append in interface LinearSeq<T>

Specified by:

append in interface Seq<T>

Parameters:

element - An element

Returns:

A new Seq containing the given element appended to this elements

appendAll

default Stream<T> appendAll(Iterable<? extends T> elements)

Description copied from interface: Seq

Appends all given elements to this.

Specified by:

appendAll in interface LinearSeq<T>

Specified by:

appendAll in interface Seq<T>

Parameters:

elements - An Iterable of elements

Returns:

A new Seq containing the given elements appended to this elements

appendSelf

default Stream<T> appendSelf(Function<? super Stream<T>,? extends Stream<T>> mapper)

Appends itself to the end of stream with mapper function.

Example:

Well known Scala code for Fibonacci infinite sequence

 
 val fibs:Stream[Int] = 0 #:: 1 #:: (fibs zip fibs.tail).map{ t => t._1 + t._2 }
 
 

can be transformed to

 
 Stream.of(0, 1).appendSelf(self -> self.zip(self.tail()).map(t -> t._1 + t._2));
 
 

Parameters:

mapper - an mapper

Returns:

a new Stream

asJava

@GwtIncompatible
default List<T> asJava()

Description copied from interface: Seq

Creates an immutable List view on top of this Seq, i.e. calling mutators will result in UnsupportedOperationException at runtime.

The difference to conversion methods toJava*() is that

• A view is created in O(1) (constant time) whereas conversion takes O(n) (linear time), with n = collection size.
• The operations on a view have the same performance characteristics than the underlying persistent Vavr collection whereas the performance characteristics of a converted collection are those of the Java standard collections.

Please note that our immutable java.util.List view throws UnsupportedOperationException before checking method arguments. Java does handle this case inconsistently.

Specified by:

asJava in interface Seq<T>

Returns:

A new immutable Collection view on this Traversable.

asJava

@GwtIncompatible
default Stream<T> asJava(Consumer<? super List<T>> action)

Description copied from interface: Seq

Creates an immutable List view on top of this Seq that is passed to the given action.

Specified by:

asJava in interface LinearSeq<T>

Specified by:

asJava in interface Seq<T>

Parameters:

action - A side-effecting unit of work that operates on an immutable java.util.List view.

Returns:

this instance

See Also:

• Seq.asJava()

asJavaMutable

@GwtIncompatible
default List<T> asJavaMutable()

Description copied from interface: Seq

Creates a mutable List view on top of this Seq, i.e. all mutator methods of the List are implemented.

Specified by:

asJavaMutable in interface Seq<T>

Returns:

A new mutable Collection view on this Traversable.

See Also:

• Seq.asJava()

asJavaMutable

@GwtIncompatible
default Stream<T> asJavaMutable(Consumer<? super List<T>> action)

Description copied from interface: Seq

Creates a mutable List view on top of this Seq that is passed to the given action.

Specified by:

asJavaMutable in interface LinearSeq<T>

Specified by:

asJavaMutable in interface Seq<T>

Parameters:

action - A side-effecting unit of work that operates on a mutable java.util.List view.

Returns:

this instance, if only read operations are performed on the java.util.List view or a new instance of this type, if write operations are performed on the java.util.List view.

See Also:

• Seq.asJavaMutable()

collect

default <R> Stream<R> collect(PartialFunction<? super T,? extends R> partialFunction)

Description copied from interface: Traversable

Collects all elements that are in the domain of the given partialFunction by mapping the elements to type R.

More specifically, for each of this elements in iteration order first it is checked

 partialFunction.isDefinedAt(element)
 

If the elements makes it through that filter, the mapped instance is added to the result collection

 R newElement = partialFunction.apply(element)
 

Note:If this Traversable is ordered (i.e. extends Ordered, the caller of collect has to ensure that the elements are comparable (i.e. extend Comparable).

Specified by:

collect in interface LinearSeq<T>

Specified by:

collect in interface Seq<T>

Specified by:

collect in interface Traversable<T>

Type Parameters:

R - The new element type

Parameters:

partialFunction - A function that is not necessarily defined of all elements of this traversable.

Returns:

A new Traversable instance containing elements of type R

combinations

default Stream<Stream<T>> combinations()

Description copied from interface: Seq

Returns the union of all combinations from k = 0 to length().

Examples:

 
 [].combinations() = [[]]

 [1,2,3].combinations() = [
   [],                  // k = 0
   [1], [2], [3],       // k = 1
   [1,2], [1,3], [2,3], // k = 2
   [1,2,3]              // k = 3
 ]
 
 

Specified by:

combinations in interface LinearSeq<T>

Specified by:

combinations in interface Seq<T>

Returns:

the combinations of this

combinations

default Stream<Stream<T>> combinations(int k)

Description copied from interface: Seq

Returns the k-combination of this traversable, i.e. all subset of this of k distinct elements.

Specified by:

combinations in interface LinearSeq<T>

Specified by:

combinations in interface Seq<T>

Parameters:

k - Size of subsets

Returns:

the k-combination of this elements

See Also:

• Combination

crossProduct

default Iterator<Stream<T>> crossProduct(int power)

Description copied from interface: Seq

Calculates the n-ary cartesian power (or cross product or simply product) of this.

Example:

 
 // = ((A,A), (A,B), (A,C), ..., (B,A), (B,B), ..., (Z,Y), (Z,Z))
 CharSeq.rangeClosed('A', 'Z').crossProduct(2);
 
 

Cartesian power of negative value will return empty iterator.

Example:

 
 // = ()
 CharSeq.rangeClosed('A', 'Z').crossProduct(-1);
 
 

Specified by:

crossProduct in interface LinearSeq<T>

Specified by:

crossProduct in interface Seq<T>

Parameters:

power - the number of cartesian multiplications

Returns:

A new Iterator representing the n-ary cartesian power of this

cycle

default Stream<T> cycle()

Repeat the elements of this Stream infinitely.

Example:

 
 // = 1, 2, 3, 1, 2, 3, 1, 2, 3, ...
 Stream.of(1, 2, 3).cycle();
 
 

Returns:

A new Stream containing this elements cycled.

cycle

default Stream<T> cycle(int count)

Repeat the elements of this Stream count times.

Example:

 
 // = empty
 Stream.of(1, 2, 3).cycle(0);

 // = 1, 2, 3
 Stream.of(1, 2, 3).cycle(1);

 // = 1, 2, 3, 1, 2, 3, 1, 2, 3
 Stream.of(1, 2, 3).cycle(3);
 
 

Parameters:

count - the number of cycles to be performed

Returns:

A new Stream containing this elements cycled count times.

distinct

default Stream<T> distinct()

Description copied from interface: Traversable

Returns a new version of this which contains no duplicates. Elements are compared using equals.

Specified by:

distinct in interface LinearSeq<T>

Specified by:

distinct in interface Seq<T>

Specified by:

distinct in interface Traversable<T>

Returns:

a new Traversable containing this elements without duplicates

distinctBy

default Stream<T> distinctBy(Comparator<? super T> comparator)

Description copied from interface: Traversable

Returns a new version of this which contains no duplicates. Elements are compared using the given comparator.

Specified by:

distinctBy in interface LinearSeq<T>

Specified by:

distinctBy in interface Seq<T>

Specified by:

distinctBy in interface Traversable<T>

Parameters:

comparator - A comparator

Returns:

a new Traversable containing this elements without duplicates

distinctBy

default <U> Stream<T> distinctBy(Function<? super T,? extends U> keyExtractor)

Description copied from interface: Traversable

Returns a new version of this which contains no duplicates. Elements mapped to keys which are compared using equals.

The elements of the result are determined in the order of their occurrence - first match wins.

Specified by:

distinctBy in interface LinearSeq<T>

Specified by:

distinctBy in interface Seq<T>

Specified by:

distinctBy in interface Traversable<T>

Type Parameters:

U - key type

Parameters:

keyExtractor - A key extractor

Returns:

a new Traversable containing this elements without duplicates

drop

default Stream<T> drop(int n)

Description copied from interface: Traversable

Drops the first n elements of this or all elements, if this length < n.

Specified by:

drop in interface LinearSeq<T>

Specified by:

drop in interface Seq<T>

Specified by:

drop in interface Traversable<T>

Parameters:

n - The number of elements to drop.

Returns:

a new instance consisting of all elements of this except the first n ones, or else the empty instance, if this has less than n elements.

dropUntil

default Stream<T> dropUntil(Predicate<? super T> predicate)

Description copied from interface: Traversable

Drops elements until the predicate holds for the current element.

Specified by:

dropUntil in interface LinearSeq<T>

Specified by:

dropUntil in interface Seq<T>

Specified by:

dropUntil in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for this elements.

Returns:

a new instance consisting of all elements starting from the first one which does satisfy the given predicate.

dropWhile

default Stream<T> dropWhile(Predicate<? super T> predicate)

Description copied from interface: Traversable

Drops elements while the predicate holds for the current element.

Note: This is essentially the same as dropUntil(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

Specified by:

dropWhile in interface LinearSeq<T>

Specified by:

dropWhile in interface Seq<T>

Specified by:

dropWhile in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for this elements.

Returns:

a new instance consisting of all elements starting from the first one which does not satisfy the given predicate.

dropRight

default Stream<T> dropRight(int n)

Description copied from interface: Traversable

Drops the last n elements of this or all elements, if this length < n.

Specified by:

dropRight in interface LinearSeq<T>

Specified by:

dropRight in interface Seq<T>

Specified by:

dropRight in interface Traversable<T>

Parameters:

n - The number of elements to drop.

Returns:

a new instance consisting of all elements of this except the last n ones, or else the empty instance, if this has less than n elements.

dropRightUntil

default Stream<T> dropRightUntil(Predicate<? super T> predicate)

Description copied from interface: Seq

Drops elements until the predicate holds for the current element, starting from the end.

Specified by:

dropRightUntil in interface LinearSeq<T>

Specified by:

dropRightUntil in interface Seq<T>

Parameters:

predicate - A condition tested subsequently for this elements, starting from the end.

Returns:

a new instance consisting of all elements until and including the last one which does satisfy the given predicate.

dropRightWhile

default Stream<T> dropRightWhile(Predicate<? super T> predicate)

Description copied from interface: Seq

Drops elements while the predicate holds for the current element, starting from the end.

Note: This is essentially the same as dropRightUntil(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

Specified by:

dropRightWhile in interface LinearSeq<T>

Specified by:

dropRightWhile in interface Seq<T>

Parameters:

predicate - A condition tested subsequently for this elements, starting from the end.

Returns:

a new instance consisting of all elements until and including the last one which does not satisfy the given predicate.

filter

default Stream<T> filter(Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a new traversable consisting of all elements which satisfy the given predicate.

Specified by:

filter in interface LinearSeq<T>

Specified by:

filter in interface Seq<T>

Specified by:

filter in interface Traversable<T>

Parameters:

predicate - A predicate

Returns:

a new traversable

reject

default Stream<T> reject(Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a new traversable consisting of all elements which do not satisfy the given predicate.

The default implementation is equivalent to

filter(predicate.negate()

Specified by:

reject in interface LinearSeq<T>

Specified by:

reject in interface Seq<T>

Specified by:

reject in interface Traversable<T>

Parameters:

predicate - A predicate

Returns:

a new traversable

flatMap

default <U> Stream<U> flatMap(Function<? super T,? extends Iterable<? extends U>> mapper)

Description copied from interface: Traversable

FlatMaps this Traversable.

Specified by:

flatMap in interface LinearSeq<T>

Specified by:

flatMap in interface Seq<T>

Specified by:

flatMap in interface Traversable<T>

Type Parameters:

U - The resulting component type.

Parameters:

mapper - A mapper

Returns:

A new Traversable instance.

get

default T get(int index)

Description copied from interface: Seq

Returns the element at the specified index.

Specified by:

get in interface Seq<T>

Parameters:

index - an index

Returns:

the element at the given index

groupBy

default <C> Map<C,Stream<T>> groupBy(Function<? super T,? extends C> classifier)

Description copied from interface: Traversable

Groups this elements by classifying the elements.

Specified by:

groupBy in interface LinearSeq<T>

Specified by:

groupBy in interface Seq<T>

Specified by:

groupBy in interface Traversable<T>

Type Parameters:

C - classified class type

Parameters:

classifier - A function which classifies elements into classes

Returns:

A Map containing the grouped elements

See Also:

• Traversable.arrangeBy(Function)

grouped

default Iterator<Stream<T>> grouped(int size)

Description copied from interface: Traversable

Groups this Traversable into fixed size blocks.

Let length be the length of this Iterable. Then grouped is defined as follows:

• If this.isEmpty(), the resulting Iterator is empty.
• If size <= length, the resulting Iterator will contain length / size blocks of size size and maybe a non-empty block of size length % size, if there are remaining elements.
• If size > length, the resulting Iterator will contain one block of size length.

Examples:

 
 [].grouped(1) = []
 [].grouped(0) throws
 [].grouped(-1) throws
 [1,2,3,4].grouped(2) = [[1,2],[3,4]]
 [1,2,3,4,5].grouped(2) = [[1,2],[3,4],[5]]
 [1,2,3,4].grouped(5) = [[1,2,3,4]]
 
 

Please note that grouped(int) is a special case of Traversable.sliding(int, int), i.e. grouped(size) is the same as sliding(size, size).

Specified by:

grouped in interface LinearSeq<T>

Specified by:

grouped in interface Seq<T>

Specified by:

grouped in interface Traversable<T>

Parameters:

size - a positive block size

Returns:

A new Iterator of grouped blocks of the given size

hasDefiniteSize

default boolean hasDefiniteSize()

Description copied from interface: Traversable

Checks if this Traversable is known to have a finite size.

This method should be implemented by classes only, i.e. not by interfaces.

Specified by:

hasDefiniteSize in interface Traversable<T>

Returns:

true, if this Traversable is known to have a finite size, false otherwise.

indexOf

default int indexOf(T element,
 int from)

Description copied from interface: Seq

Returns the index of the first occurrence of the given element after or at some start index or -1 if this does not contain the given element.

Specified by:

indexOf in interface Seq<T>

Parameters:

element - an element

from - start index

Returns:

the index of the first occurrence of the given element

init

default Stream<T> init()

Description copied from interface: Traversable

Dual of Traversable.tail(), returning all elements except the last.

Specified by:

init in interface LinearSeq<T>

Specified by:

init in interface Seq<T>

Specified by:

init in interface Traversable<T>

Returns:

a new instance containing all elements except the last.

initOption

default Option<Stream<T>> initOption()

Description copied from interface: Traversable

Dual of Traversable.tailOption(), returning all elements except the last as Option.

Specified by:

initOption in interface LinearSeq<T>

Specified by:

initOption in interface Seq<T>

Specified by:

initOption in interface Traversable<T>

Returns:

Some(traversable) or None if this is empty.

insert

default Stream<T> insert(int index,
 T element)

Description copied from interface: Seq

Inserts the given element at the specified index.

Specified by:

insert in interface LinearSeq<T>

Specified by:

insert in interface Seq<T>

Parameters:

index - an index

element - an element

Returns:

a new Seq, where the given element is inserted into this at the given index

insertAll

default Stream<T> insertAll(int index,
 Iterable<? extends T> elements)

Description copied from interface: Seq

Inserts the given elements at the specified index.

Specified by:

insertAll in interface LinearSeq<T>

Specified by:

insertAll in interface Seq<T>

Parameters:

index - an index

elements - An Iterable of elements

Returns:

a new Seq, where the given elements are inserted into this at the given index

intersperse

default Stream<T> intersperse(T element)

Description copied from interface: Seq

Inserts an element between all elements of this Traversable.

Specified by:

intersperse in interface LinearSeq<T>

Specified by:

intersperse in interface Seq<T>

Parameters:

element - An element.

Returns:

an interspersed version of this

isAsync

default boolean isAsync()

A Stream is computed synchronously.

Specified by:

isAsync in interface Value<T>

Returns:

false

isLazy

default boolean isLazy()

A Stream is computed lazily.

Specified by:

isLazy in interface Value<T>

Returns:

true

isTraversableAgain

default boolean isTraversableAgain()

Description copied from interface: Traversable

Checks if this Traversable can be repeatedly traversed.

This method should be implemented by classes only, i.e. not by interfaces.

Specified by:

isTraversableAgain in interface Traversable<T>

Returns:

true, if this Traversable is known to be traversable repeatedly, false otherwise.

last

default T last()

Description copied from interface: Traversable

Dual of Traversable.head(), returning the last element.

Specified by:

last in interface Traversable<T>

Returns:

the last element.

lastIndexOf

default int lastIndexOf(T element,
 int end)

Description copied from interface: Seq

Returns the index of the last occurrence of the given element before or at a given end index or -1 if this does not contain the given element.

Specified by:

lastIndexOf in interface Seq<T>

Parameters:

element - an element

end - the end index

Returns:

the index of the last occurrence of the given element

length

default int length()

Description copied from interface: Traversable

Computes the number of elements of this Traversable.

Same as Traversable.size().

Specified by:

length in interface Traversable<T>

Returns:

the number of elements

map

default <U> Stream<U> map(Function<? super T,? extends U> mapper)

Description copied from interface: Traversable

Maps the elements of this Traversable to elements of a new type preserving their order, if any.

Specified by:

map in interface LinearSeq<T>

Specified by:

map in interface Seq<T>

Specified by:

map in interface Traversable<T>

Specified by:

map in interface Value<T>

Type Parameters:

U - Component type of the target Traversable

Parameters:

mapper - A mapper.

Returns:

a mapped Traversable

padTo

default Stream<T> padTo(int length,
 T element)

Description copied from interface: Seq

A copy of this sequence with an element appended until a given target length is reached.

Note: lazily-evaluated Seq implementations need to process all elements in order to gather the overall length.

Specified by:

padTo in interface LinearSeq<T>

Specified by:

padTo in interface Seq<T>

Parameters:

length - the target length

element - the padding element

Returns:

a new sequence consisting of all elements of this sequence followed by the minimal number of occurrences of element so that the resulting sequence has a length of at least length.

leftPadTo

default Stream<T> leftPadTo(int length,
 T element)

Description copied from interface: Seq

A copy of this sequence with an element prepended until a given target length is reached.

Note: lazily-evaluated Seq implementations need to process all elements in order to gather the overall length.

Specified by:

leftPadTo in interface Seq<T>

Parameters:

length - the target length

element - the padding element

Returns:

a new sequence consisting of all elements of this sequence prepended by the minimal number of occurrences of element so that the resulting sequence has a length of at least length.

orElse

default Stream<T> orElse(Iterable<? extends T> other)

Description copied from interface: Traversable

Returns this Traversable if it is nonempty, otherwise return the alternative.

Specified by:

orElse in interface LinearSeq<T>

Specified by:

orElse in interface Seq<T>

Specified by:

orElse in interface Traversable<T>

Parameters:

other - An alternative Traversable

Returns:

this Traversable if it is nonempty, otherwise return the alternative.

orElse

default Stream<T> orElse(Supplier<? extends Iterable<? extends T>> supplier)

Description copied from interface: Traversable

Returns this Traversable if it is nonempty, otherwise return the result of evaluating supplier.

Specified by:

orElse in interface LinearSeq<T>

Specified by:

orElse in interface Seq<T>

Specified by:

orElse in interface Traversable<T>

Parameters:

supplier - An alternative Traversable supplier

Returns:

this Traversable if it is nonempty, otherwise return the result of evaluating supplier.

patch

default Stream<T> patch(int from,
 Iterable<? extends T> that,
 int replaced)

Description copied from interface: Seq

Produces a new list where a slice of elements in this list is replaced by another sequence.

Specified by:

patch in interface LinearSeq<T>

Specified by:

patch in interface Seq<T>

Parameters:

from - the index of the first replaced element

that - sequence for replacement

replaced - the number of elements to drop in the original list

Returns:

a new sequence.

partition

default Tuple2<Stream<T>,Stream<T>> partition(Predicate<? super T> predicate)

Description copied from interface: Traversable

Creates a partition of this Traversable by splitting this elements in two in distinct traversables according to a predicate.

Specified by:

partition in interface LinearSeq<T>

Specified by:

partition in interface Seq<T>

Specified by:

partition in interface Traversable<T>

Parameters:

predicate - A predicate which classifies an element if it is in the first or the second traversable.

Returns:

A disjoint union of two traversables. The first Traversable contains all elements that satisfy the given predicate, the second Traversable contains all elements that don't. The original order of elements is preserved.

peek

default Stream<T> peek(Consumer<? super T> action)

Description copied from interface: Value

Performs the given action on the first element if this is an eager implementation. Performs the given action on all elements (the first immediately, successive deferred), if this is a lazy implementation.

Specified by:

peek in interface LinearSeq<T>

Specified by:

peek in interface Seq<T>

Specified by:

peek in interface Traversable<T>

Specified by:

peek in interface Value<T>

Parameters:

action - The action that will be performed on the element(s).

Returns:

this instance

permutations

default Stream<Stream<T>> permutations()

Description copied from interface: Seq

Computes all unique permutations.

Example:

 
 [].permutations() = []

 [1,2,3].permutations() = [
   [1,2,3],
   [1,3,2],
   [2,1,3],
   [2,3,1],
   [3,1,2],
   [3,2,1]
 ]
 
 

Specified by:

permutations in interface LinearSeq<T>

Specified by:

permutations in interface Seq<T>

Returns:

this unique permutations

prepend

default Stream<T> prepend(T element)

Description copied from interface: Seq

Prepends an element to this.

Specified by:

prepend in interface LinearSeq<T>

Specified by:

prepend in interface Seq<T>

Parameters:

element - An element

Returns:

A new Seq containing the given element prepended to this elements

prependAll

default Stream<T> prependAll(Iterable<? extends T> elements)

Description copied from interface: Seq

Prepends all given elements to this.

Specified by:

prependAll in interface LinearSeq<T>

Specified by:

prependAll in interface Seq<T>

Parameters:

elements - An Iterable of elements

Returns:

A new Seq containing the given elements prepended to this elements

remove

default Stream<T> remove(T element)

Description copied from interface: Seq

Removes the first occurrence of the given element.

Specified by:

remove in interface LinearSeq<T>

Specified by:

remove in interface Seq<T>

Parameters:

element - An element to be removed from this Seq.

Returns:

a Seq containing all elements of this without the first occurrence of the given element.

removeFirst

default Stream<T> removeFirst(Predicate<T> predicate)

Description copied from interface: Seq

Removes the first occurrence that satisfy predicate

Specified by:

removeFirst in interface LinearSeq<T>

Specified by:

removeFirst in interface Seq<T>

Parameters:

predicate - an predicate

Returns:

a new Seq

removeLast

default Stream<T> removeLast(Predicate<T> predicate)

Description copied from interface: Seq

Removes the last occurrence that satisfy predicate

Specified by:

removeLast in interface LinearSeq<T>

Specified by:

removeLast in interface Seq<T>

Parameters:

predicate - an predicate

Returns:

a new Seq

removeAt

default Stream<T> removeAt(int index)

Description copied from interface: Seq

Removes the element at the specified position in this sequence. Shifts any subsequent elements to the left (subtracts one from their indices).

Specified by:

removeAt in interface LinearSeq<T>

Specified by:

removeAt in interface Seq<T>

Parameters:

index - position of element to remove

Returns:

a sequence containing all elements of this without the element at the specified position.

removeAll

default Stream<T> removeAll(T element)

Description copied from interface: Seq

Removes all occurrences of the given element.

Specified by:

removeAll in interface LinearSeq<T>

Specified by:

removeAll in interface Seq<T>

Parameters:

element - An element to be removed from this Seq.

Returns:

a Seq containing all elements of this but not the given element.

removeAll

default Stream<T> removeAll(Iterable<? extends T> elements)

Description copied from interface: Seq

Removes all occurrences of the given elements.

Specified by:

removeAll in interface LinearSeq<T>

Specified by:

removeAll in interface Seq<T>

Parameters:

elements - Elements to be removed from this Seq.

Returns:

a Seq containing all elements of this but none of the given elements.

removeAll

@Deprecated
default Stream<T> removeAll(Predicate<? super T> predicate)

Deprecated.

Description copied from interface: Seq

Returns a new Seq consisting of all elements which do not satisfy the given predicate.

Specified by:

removeAll in interface LinearSeq<T>

Specified by:

removeAll in interface Seq<T>

Parameters:

predicate - the predicate used to test elements

Returns:

a new Seq

replace

default Stream<T> replace(T currentElement,
 T newElement)

Description copied from interface: Traversable

Replaces the first occurrence (if exists) of the given currentElement with newElement.

Specified by:

replace in interface LinearSeq<T>

Specified by:

replace in interface Seq<T>

Specified by:

replace in interface Traversable<T>

Parameters:

currentElement - An element to be substituted.

newElement - A replacement for currentElement.

Returns:

a Traversable containing all elements of this where the first occurrence of currentElement is replaced with newElement.

replaceAll

default Stream<T> replaceAll(T currentElement,
 T newElement)

Description copied from interface: Traversable

Replaces all occurrences of the given currentElement with newElement.

Specified by:

replaceAll in interface LinearSeq<T>

Specified by:

replaceAll in interface Seq<T>

Specified by:

replaceAll in interface Traversable<T>

Parameters:

currentElement - An element to be substituted.

newElement - A replacement for currentElement.

Returns:

a Traversable containing all elements of this where all occurrences of currentElement are replaced with newElement.

retainAll

default Stream<T> retainAll(Iterable<? extends T> elements)

Description copied from interface: Traversable

Keeps all occurrences of the given elements from this.

Specified by:

retainAll in interface LinearSeq<T>

Specified by:

retainAll in interface Seq<T>

Specified by:

retainAll in interface Traversable<T>

Parameters:

elements - Elements to be kept.

Returns:

a Traversable containing all occurrences of the given elements.

reverse

default Stream<T> reverse()

Description copied from interface: Seq

Reverses the order of elements.

Specified by:

reverse in interface LinearSeq<T>

Specified by:

reverse in interface Seq<T>

Returns:

the reversed elements.

rotateLeft

default Stream<T> rotateLeft(int n)

Description copied from interface: Seq

Circular rotates the elements by the specified distance to the left direction.

 // = List(3, 4, 5, 1, 2)
 List.of(1, 2, 3, 4, 5).rotateLeft(2);
 

Specified by:

rotateLeft in interface LinearSeq<T>

Specified by:

rotateLeft in interface Seq<T>

Parameters:

n - distance of left rotation

Returns:

the rotated elements.

rotateRight

default Stream<T> rotateRight(int n)

Description copied from interface: Seq

Circular rotates the elements by the specified distance to the right direction.

 // = List(4, 5, 1, 2, 3)
 List.of(1, 2, 3, 4, 5).rotateRight(2);
 

Specified by:

rotateRight in interface LinearSeq<T>

Specified by:

rotateRight in interface Seq<T>

Parameters:

n - distance of right rotation

Returns:

the rotated elements.

scan

default Stream<T> scan(T zero,
 BiFunction<? super T,? super T,? extends T> operation)

Description copied from interface: Traversable

Computes a prefix scan of the elements of the collection. Note: The neutral element z may be applied more than once.

Specified by:

scan in interface LinearSeq<T>

Specified by:

scan in interface Seq<T>

Specified by:

scan in interface Traversable<T>

Parameters:

zero - neutral element for the operator op

operation - the associative operator for the scan

Returns:

a new traversable collection containing the prefix scan of the elements in this traversable collection

scanLeft

default <U> Stream<U> scanLeft(U zero,
 BiFunction<? super U,? super T,? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator going left to right. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.

Specified by:

scanLeft in interface LinearSeq<T>

Specified by:

scanLeft in interface Seq<T>

Specified by:

scanLeft in interface Traversable<T>

Type Parameters:

U - the type of the elements in the resulting collection

Parameters:

zero - the initial value

operation - the binary operator applied to the intermediate result and the element

Returns:

collection with intermediate results

scanRight

default <U> Stream<U> scanRight(U zero,
 BiFunction<? super T,? super U,? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.

Specified by:

scanRight in interface LinearSeq<T>

Specified by:

scanRight in interface Seq<T>

Specified by:

scanRight in interface Traversable<T>

Type Parameters:

U - the type of the elements in the resulting collection

Parameters:

zero - the initial value

operation - the binary operator applied to the intermediate result and the element

Returns:

collection with intermediate results

shuffle

default Stream<T> shuffle()

Description copied from interface: Seq

Randomize the order of the elements in the current sequence.

Specified by:

shuffle in interface LinearSeq<T>

Specified by:

shuffle in interface Seq<T>

Returns:

a sequence with the same elements as the current sequence in a random order.

slice

default Stream<T> slice(int beginIndex,
 int endIndex)

Description copied from interface: Seq

Returns a Seq that is a slice of this. The slice begins with the element at the specified beginIndex and extends to the element at index endIndex - 1.

Examples:

 
 List.of(1, 2, 3, 4).slice(1, 3); // = (2, 3)
 List.of(1, 2, 3, 4).slice(0, 4); // = (1, 2, 3, 4)
 List.of(1, 2, 3, 4).slice(2, 2); // = ()
 List.of(1, 2).slice(1, 0);       // = ()
 List.of(1, 2).slice(-10, 10);    // = (1, 2)
 
 

See also Seq.subSequence(int, int) which throws in some cases instead of returning a sequence.

Specified by:

slice in interface LinearSeq<T>

Specified by:

slice in interface Seq<T>

Parameters:

beginIndex - the beginning index, inclusive

endIndex - the end index, exclusive

Returns:

the specified slice

slideBy

default Iterator<Stream<T>> slideBy(Function<? super T,?> classifier)

Description copied from interface: Traversable

Slides a non-overlapping window of a variable size over this Traversable.

Each window contains elements with the same class, as determined by classifier. Two consecutive values in this Traversable will be in the same window only if classifier returns equal values for them. Otherwise, the values will constitute the last element of the previous window and the first element of the next window.

Examples:

 [].slideBy(Function.identity()) = []
 [1,2,3,4,4,5].slideBy(Function.identity()) = [[1],[2],[3],[4,4],[5]]
 [1,2,3,10,12,5,7,20,29].slideBy(x -> x/10) = [[1,2,3],[10,12],[5,7],[20,29]]
 

Specified by:

slideBy in interface LinearSeq<T>

Specified by:

slideBy in interface Seq<T>

Specified by:

slideBy in interface Traversable<T>

Parameters:

classifier - A function which classifies elements into classes

Returns:

A new Iterator of windows of the grouped elements

sliding

default Iterator<Stream<T>> sliding(int size)

Description copied from interface: Traversable

Slides a window of a specific size and step size 1 over this Traversable by calling Traversable.sliding(int, int).

Specified by:

sliding in interface LinearSeq<T>

Specified by:

sliding in interface Seq<T>

Specified by:

sliding in interface Traversable<T>

Parameters:

size - a positive window size

Returns:

a new Iterator of windows of a specific size using step size 1

sliding

default Iterator<Stream<T>> sliding(int size,
 int step)

Description copied from interface: Traversable

Slides a window of a specific size and step size over this Traversable.

Examples:

 
 [].sliding(1,1) = []
 [1,2,3,4,5].sliding(2,3) = [[1,2],[4,5]]
 [1,2,3,4,5].sliding(2,4) = [[1,2],[5]]
 [1,2,3,4,5].sliding(2,5) = [[1,2]]
 [1,2,3,4].sliding(5,3) = [[1,2,3,4],[4]]
 
 

Specified by:

sliding in interface LinearSeq<T>

Specified by:

sliding in interface Seq<T>

Specified by:

sliding in interface Traversable<T>

Parameters:

size - a positive window size

step - a positive step size

Returns:

a new Iterator of windows of a specific size using a specific step size

sorted

default Stream<T> sorted()

Description copied from interface: Seq

Sorts this elements according to their natural order. If this elements are not Comparable, a java.lang.ClassCastException may be thrown.

Specified by:

sorted in interface LinearSeq<T>

Specified by:

sorted in interface Seq<T>

Returns:

A sorted version of this

sorted

default Stream<T> sorted(Comparator<? super T> comparator)

Description copied from interface: Seq

Sorts this elements according to the provided Comparator. If this elements are not Comparable, a java.lang.ClassCastException may be thrown.

Specified by:

sorted in interface LinearSeq<T>

Specified by:

sorted in interface Seq<T>

Parameters:

comparator - A comparator

Returns:

a sorted version of this

sortBy

default <U extends Comparable<? super U>> Stream<T> sortBy(Function<? super T,? extends U> mapper)

Description copied from interface: Seq

Sorts this elements by comparing the elements in a different domain, using the given mapper.

Specified by:

sortBy in interface LinearSeq<T>

Specified by:

sortBy in interface Seq<T>

Type Parameters:

U - The domain where elements are compared

Parameters:

mapper - A mapper

Returns:

a sorted version of this

sortBy

default <U> Stream<T> sortBy(Comparator<? super U> comparator,
 Function<? super T,? extends U> mapper)

Description copied from interface: Seq

Sorts this elements by comparing the elements in a different domain, using the given mapper.

Specified by:

sortBy in interface LinearSeq<T>

Specified by:

sortBy in interface Seq<T>

Type Parameters:

U - The domain where elements are compared

Parameters:

comparator - A comparator

mapper - A mapper

Returns:

a sorted version of this

span

default Tuple2<Stream<T>,Stream<T>> span(Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a tuple where the first element is the longest prefix of elements that satisfy the given predicate and the second element is the remainder.

Specified by:

span in interface LinearSeq<T>

Specified by:

span in interface Seq<T>

Specified by:

span in interface Traversable<T>

Parameters:

predicate - A predicate.

Returns:

a Tuple containing the longest prefix of elements that satisfy p and the remainder.

splitAt

default Tuple2<Stream<T>,Stream<T>> splitAt(int n)

Description copied from interface: Seq

Splits a Seq at the specified index. The result of splitAt(n) is equivalent to Tuple.of(take(n), drop(n)).

Specified by:

splitAt in interface Seq<T>

Parameters:

n - An index.

Returns:

A Tuple containing the first n and the remaining elements.

splitAt

default Tuple2<Stream<T>,Stream<T>> splitAt(Predicate<? super T> predicate)

Description copied from interface: Seq

Splits a sequence at the first element which satisfies the Predicate, e.g. Tuple(init, element+tail).

Specified by:

splitAt in interface Seq<T>

Parameters:

predicate - An predicate

Returns:

A Tuple containing divided sequences

splitAtInclusive

default Tuple2<Stream<T>,Stream<T>> splitAtInclusive(Predicate<? super T> predicate)

Description copied from interface: Seq

Splits a sequence at the first element which satisfies the Predicate, e.g. Tuple(init+element, tail).

Specified by:

splitAtInclusive in interface Seq<T>

Parameters:

predicate - An predicate

Returns:

A Tuple containing divided sequences

stringPrefix

default String stringPrefix()

Description copied from interface: Value

Returns the name of this Value type, which is used by toString().

Specified by:

stringPrefix in interface Value<T>

Returns:

This type name.

subSequence

default Stream<T> subSequence(int beginIndex)

Description copied from interface: Seq

Returns a Seq that is a subsequence of this. The subsequence begins with the element at the specified beginIndex and extends to the end of this Seq.

Examples:

 
 List.of(1, 2).subSequence(0);     // = (1, 2)
 List.of(1, 2).subSequence(1);     // = (2)
 List.of(1, 2).subSequence(2);     // = ()
 List.of(1, 2).subSequence(10);    // throws IndexOutOfBoundsException
 List.of(1, 2).subSequence(-10);   // throws IndexOutOfBoundsException
 
 

See also Seq.drop(int) which is similar but does not throw.

Specified by:

subSequence in interface LinearSeq<T>

Specified by:

subSequence in interface Seq<T>

Parameters:

beginIndex - the beginning index, inclusive

Returns:

the specified subsequence

subSequence

default Stream<T> subSequence(int beginIndex,
 int endIndex)

Description copied from interface: Seq

Returns a Seq that is a subsequence of this. The subsequence begins with the element at the specified beginIndex and extends to the element at index endIndex - 1.

Examples:

 
 List.of(1, 2, 3, 4).subSequence(1, 3); // = (2, 3)
 List.of(1, 2, 3, 4).subSequence(0, 4); // = (1, 2, 3, 4)
 List.of(1, 2, 3, 4).subSequence(2, 2); // = ()
 List.of(1, 2).subSequence(1, 0);       // throws IndexOutOfBoundsException
 List.of(1, 2).subSequence(-10, 1);     // throws IndexOutOfBoundsException
 List.of(1, 2).subSequence(0, 10);      // throws IndexOutOfBoundsException
 
 

See also Seq.slice(int, int) which returns an empty sequence instead of throwing.

Specified by:

subSequence in interface LinearSeq<T>

Specified by:

subSequence in interface Seq<T>

Parameters:

beginIndex - the beginning index, inclusive

endIndex - the end index, exclusive

Returns:

the specified subsequence

tail

Stream<T> tail()

Description copied from interface: Traversable

Drops the first element of a non-empty Traversable.

Specified by:

tail in interface LinearSeq<T>

Specified by:

tail in interface Seq<T>

Specified by:

tail in interface Traversable<T>

Returns:

A new instance of Traversable containing all elements except the first.

tailOption

default Option<Stream<T>> tailOption()

Description copied from interface: Traversable

Drops the first element of a non-empty Traversable and returns an Option.

Specified by:

tailOption in interface LinearSeq<T>

Specified by:

tailOption in interface Seq<T>

Specified by:

tailOption in interface Traversable<T>

Returns:

Some(traversable) or None if this is empty.

take

default Stream<T> take(int n)

Description copied from interface: Traversable

Takes the first n elements of this or all elements, if this length < n.

The result is equivalent to sublist(0, max(0, min(length(), n))) but does not throw if n < 0 or n > length().

In the case of n < 0 the empty instance is returned, in the case of n > length() this is returned.

Specified by:

take in interface LinearSeq<T>

Specified by:

take in interface Seq<T>

Specified by:

take in interface Traversable<T>

Parameters:

n - The number of elements to take.

Returns:

A new instance consisting of the first n elements of this or all elements, if this has less than n elements.

takeUntil

default Stream<T> takeUntil(Predicate<? super T> predicate)

Description copied from interface: Traversable

Takes elements until the predicate holds for the current element.

Note: This is essentially the same as takeWhile(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

Specified by:

takeUntil in interface LinearSeq<T>

Specified by:

takeUntil in interface Seq<T>

Specified by:

takeUntil in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for this elements.

Returns:

a new instance consisting of all elements before the first one which does satisfy the given predicate.

takeWhile

default Stream<T> takeWhile(Predicate<? super T> predicate)

Description copied from interface: Traversable

Takes elements while the predicate holds for the current element.

Specified by:

takeWhile in interface LinearSeq<T>

Specified by:

takeWhile in interface Seq<T>

Specified by:

takeWhile in interface Traversable<T>

Parameters:

predicate - A condition tested subsequently for the contained elements.

Returns:

a new instance consisting of all elements before the first one which does not satisfy the given predicate.

takeRight

default Stream<T> takeRight(int n)

Description copied from interface: Traversable

Takes the last n elements of this or all elements, if this length < n.

The result is equivalent to sublist(max(0, min(length(), length() - n)), n), i.e. takeRight will not throw if n < 0 or n > length().

In the case of n < 0 the empty instance is returned, in the case of n > length() this is returned.

Specified by:

takeRight in interface LinearSeq<T>

Specified by:

takeRight in interface Seq<T>

Specified by:

takeRight in interface Traversable<T>

Parameters:

n - The number of elements to take.

Returns:

A new instance consisting of the last n elements of this or all elements, if this has less than n elements.

takeRightUntil

default Stream<T> takeRightUntil(Predicate<? super T> predicate)

Description copied from interface: Seq

Takes elements until the predicate holds for the current element, starting from the end.

Specified by:

takeRightUntil in interface LinearSeq<T>

Specified by:

takeRightUntil in interface Seq<T>

Parameters:

predicate - A condition tested subsequently for this elements, starting from the end.

Returns:

a new instance consisting of all elements after the last one which does satisfy the given predicate.

takeRightWhile

default Stream<T> takeRightWhile(Predicate<? super T> predicate)

Description copied from interface: Seq

Takes elements while the predicate holds for the current element, starting from the end.

Note: This is essentially the same as takeRightUntil(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

Specified by:

takeRightWhile in interface LinearSeq<T>

Specified by:

takeRightWhile in interface Seq<T>

Parameters:

predicate - A condition tested subsequently for this elements, starting from the end.

Returns:

a new instance consisting of all elements after the last one which does not satisfy the given predicate.

transform

default <U> U transform(Function<? super Stream<T>,? extends U> f)

Transforms this Stream.

Type Parameters:

U - Type of transformation result

Parameters:

f - A transformation

Returns:

An instance of type U

Throws:

NullPointerException - if f is null

unzip

default <T1,
T2> Tuple2<Stream<T1>,Stream<T2>> unzip(Function<? super T,Tuple2<? extends T1,? extends T2>> unzipper)

Description copied from interface: Traversable

Unzips this elements by mapping this elements to pairs which are subsequently split into two distinct sets.

Specified by:

unzip in interface LinearSeq<T>

Specified by:

unzip in interface Seq<T>

Specified by:

unzip in interface Traversable<T>

Type Parameters:

T1 - 1st element type of a pair returned by unzipper

T2 - 2nd element type of a pair returned by unzipper

Parameters:

unzipper - a function which converts elements of this to pairs

Returns:

A pair of set containing elements split by unzipper

unzip3

default <T1,
T2,
T3>
Tuple3<Stream<T1>,Stream<T2>,Stream<T3>> unzip3(Function<? super T,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)

Description copied from interface: Traversable

Unzips this elements by mapping this elements to triples which are subsequently split into three distinct sets.

Specified by:

unzip3 in interface Seq<T>

Specified by:

unzip3 in interface Traversable<T>

Type Parameters:

T1 - 1st element type of a triplet returned by unzipper

T2 - 2nd element type of a triplet returned by unzipper

T3 - 3rd element type of a triplet returned by unzipper

Parameters:

unzipper - a function which converts elements of this to pairs

Returns:

A triplet of set containing elements split by unzipper

update

default Stream<T> update(int index,
 T element)

Description copied from interface: Seq

Updates the given element at the specified index.

Specified by:

update in interface LinearSeq<T>

Specified by:

update in interface Seq<T>

Parameters:

index - an index

element - an element

Returns:

a new Seq consisting of all previous elements, with a single one (at the given index), changed to the new value.

update

default Stream<T> update(int index,
 Function<? super T,? extends T> updater)

Description copied from interface: Seq

Updates the given element at the specified index using the specified function.

Specified by:

update in interface LinearSeq<T>

Specified by:

update in interface Seq<T>

Parameters:

index - an index

updater - a function transforming the previous value

Returns:

a new Seq consisting of all previous elements, with a single one (at the given index), changed to the new value.

zip

default <U> Stream<Tuple2<T,U>> zip(Iterable<? extends U> that)

Description copied from interface: Traversable

Returns a traversable formed from this traversable and another Iterable collection by combining corresponding elements in pairs. If one of the two iterables is longer than the other, its remaining elements are ignored.

The length of the returned traversable is the minimum of the lengths of this traversable and that iterable.

Specified by:

zip in interface LinearSeq<T>

Specified by:

zip in interface Seq<T>

Specified by:

zip in interface Traversable<T>

Type Parameters:

U - The type of the second half of the returned pairs.

Parameters:

that - The Iterable providing the second half of each result pair.

Returns:

a new traversable containing pairs consisting of corresponding elements of this traversable and that iterable.

zipWith

default <U,
R> Stream<R> zipWith(Iterable<? extends U> that,
 BiFunction<? super T,? super U,? extends R> mapper)

Description copied from interface: Traversable

Returns a traversable formed from this traversable and another Iterable collection by mapping elements. If one of the two iterables is longer than the other, its remaining elements are ignored.

The length of the returned traversable is the minimum of the lengths of this traversable and that iterable.

Specified by:

zipWith in interface LinearSeq<T>

Specified by:

zipWith in interface Seq<T>

Specified by:

zipWith in interface Traversable<T>

Type Parameters:

U - The type of the second parameter of the mapper.

R - The type of the mapped elements.

Parameters:

that - The Iterable providing the second parameter of the mapper.

mapper - a mapper.

Returns:

a new traversable containing mapped elements of this traversable and that iterable.

zipAll

default <U> Stream<Tuple2<T,U>> zipAll(Iterable<? extends U> iterable,
 T thisElem,
 U thatElem)

Description copied from interface: Traversable

Returns a traversable formed from this traversable and another Iterable by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

The length of the returned traversable is the maximum of the lengths of this traversable and that iterable.

Special case: if this traversable is shorter than that elements, and that elements contains duplicates, the resulting traversable may be shorter than the maximum of the lengths of this and that because a traversable contains an element at most once.

If this Traversable is shorter than that, thisElem values are used to fill the result. If that is shorter than this Traversable, thatElem values are used to fill the result.

Specified by:

zipAll in interface LinearSeq<T>

Specified by:

zipAll in interface Seq<T>

Specified by:

zipAll in interface Traversable<T>

Type Parameters:

U - The type of the second half of the returned pairs.

Parameters:

iterable - The Iterable providing the second half of each result pair.

thisElem - The element to be used to fill up the result if this traversable is shorter than that.

thatElem - The element to be used to fill up the result if that is shorter than this traversable.

Returns:

A new traversable containing pairs consisting of corresponding elements of this traversable and that.

zipWithIndex

default Stream<Tuple2<T,Integer>> zipWithIndex()

Description copied from interface: Traversable

Zips this traversable with its indices.

Specified by:

zipWithIndex in interface LinearSeq<T>

Specified by:

zipWithIndex in interface Seq<T>

Specified by:

zipWithIndex in interface Traversable<T>

Returns:

A new traversable containing all elements of this traversable paired with their index, starting with 0.

zipWithIndex

default <U> Stream<U> zipWithIndex(BiFunction<? super T,? super Integer,? extends U> mapper)

Description copied from interface: Traversable

Zips this traversable with its indices by applying mapper provided.

Specified by:

zipWithIndex in interface LinearSeq<T>

Specified by:

zipWithIndex in interface Seq<T>

Specified by:

zipWithIndex in interface Traversable<T>

Type Parameters:

U - The type of the mapped elements.

Parameters:

mapper - a mapper.

Returns:

a new traversable containing elements of this traversable, zipped with indices, and mapped with mapper provided.

extend

default Stream<T> extend(T next)

Extends (continues) this Stream with a constantly repeated value.

Parameters:

next - value with which the stream should be extended

Returns:

new Stream composed from this stream extended with a Stream of provided value

extend

default Stream<T> extend(Supplier<? extends T> nextSupplier)

Extends (continues) this Stream with values provided by a Supplier

Parameters:

nextSupplier - a supplier which will provide values for extending a stream

Returns:

new Stream composed from this stream extended with values provided by the supplier

extend

default Stream<T> extend(Function<? super T,? extends T> nextFunction)

Extends (continues) this Stream with a Stream of values created by applying consecutively provided Function to the last element of the original Stream.

Parameters:

nextFunction - a function which calculates the next value basing on the previous value

Returns:

new Stream composed from this stream extended with values calculated by the provided function