Interface List<T>

Type Parameters:

T - Component type of the List

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:

List.Cons, List.Nil

public interface List<T>
extends LinearSeq<T>

An immutable List is an eager sequence of elements. Its immutability makes it suitable for concurrent programming.

A List is composed of a head element and a tail List.

There are two implementations of the List interface:

• List.Nil, which represents the empty List.
• List.Cons, which represents a List containing one or more elements.

A List is a Stack in the sense that it stores elements allowing a last-in-first-out (LIFO) retrieval.

Stack API:

• peek()
• peekOption()
• pop()
• popOption()
• pop2()
• pop2Option()
• push(Object)
• push(Object[])
• pushAll(Iterable)

Methods to obtain a List:

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

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

Note: A List is primarily a Seq and extends Stack for technical reasons (so Stack does not need to wrap List).

If operating on a List, please prefer

• prepend(Object) over push(Object)
• prependAll(Iterable) over pushAll(Iterable)
• tail() over pop()
• tailOption() over popOption()

Factory method applications:

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

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

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

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

Example: Converting a String to digits

// = List(1, 2, 3)
List.of("123".toCharArray()).map(c -> Character.digit(c, 10))

See Okasaki, Chris: Purely Functional Data Structures (p. 7 ff.). Cambridge, 2003.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static final class	List.Cons<T>	Non-empty List, consisting of a head and a tail.
static final class	List.Nil<T>	Representation of the singleton empty List.

Field Summary

Fields

Modifier and Type	Field	Description
static final long	serialVersionUID	The serial version UID for serialization.

Method Summary

Modifier and Type	Method	Description
default List<T>	append(T element)	Returns a new sequence with the given element appended at the end.
default List<T>	appendAll(@NonNull Iterable<? extends T> elements)	Returns a new sequence with all elements from the given Iterable appended at the end of this sequence.
default List<T>	asJava()	Returns an immutable List view of this Seq.
default List<T>	asJava(@NonNull Consumer<? super List<T>> action)	Creates an immutable List view of this Seq and passes it to the given action.
default List<T>	asJavaMutable()	Returns a mutable List view of this Seq.
default List<T>	asJavaMutable(@NonNull Consumer<? super List<T>> action)	Creates a mutable List view of this Seq and passes it to the given action.
default <R> List<R>	collect(@NonNull PartialFunction<? super T, ? extends R> partialFunction)	Applies a PartialFunction to all elements that are defined for it and collects the results.
static <T> Collector<T, ArrayList<T>, List<T>>	collector()	Returns a Collector which may be used in conjunction with Stream.collect(java.util.stream.Collector) to obtain a List.
default List<List<T>>	combinations()	Returns a sequence containing all combinations of elements from this sequence, for all sizes from 0 to length().
default List<List<T>>	combinations(int k)	Returns all subsets of this sequence containing exactly k distinct elements, i.e., the k-combinations of this sequence.
default Iterator<List<T>>	crossProduct(int power)	Returns the n-ary Cartesian power (cross product) of this sequence.
default List<T>	distinct()	Returns a new Traversable containing the elements of this instance with all duplicates removed.
default List<T>	distinctBy(@NonNull Comparator<? super T> comparator)	Returns a new Traversable containing the elements of this instance without duplicates, as determined by the given comparator.
default <U> List<T>	distinctBy(@NonNull Function<? super T, ? extends U> keyExtractor)	Returns a new Traversable containing the elements of this instance without duplicates, based on keys extracted from elements using keyExtractor.
default List<T>	distinctByKeepLast(@NonNull Comparator<? super T> comparator)	Returns a sequence with duplicate elements removed, as determined by the provided comparator.
default <U> List<T>	distinctByKeepLast(@NonNull Function<? super T, ? extends U> keyExtractor)	Returns a sequence with duplicates removed based on a key extracted from each element.
default List<T>	drop(int n)	Returns a new Traversable without the first n elements, or an empty instance if this contains fewer than n elements.
default List<T>	dropRight(int n)	Returns a new Traversable without the last n elements, or an empty instance if this contains fewer than n elements.
default List<T>	dropRightUntil(@NonNull Predicate<? super T> predicate)	Drops elements from the end of the sequence until an element satisfies the given predicate.
default List<T>	dropRightWhile(@NonNull Predicate<? super T> predicate)	Drops elements from the end of the sequence while the given predicate holds.
default List<T>	dropUntil(@NonNull Predicate<? super T> predicate)	Returns a new Traversable starting from the first element that satisfies the given predicate, dropping all preceding elements.
default List<T>	dropWhile(@NonNull Predicate<? super T> predicate)	Returns a new Traversable starting from the first element that does not satisfy the given predicate, dropping all preceding elements.
static <T> List<T>	empty()	Returns the single instance of Nil.
static <T> List<T>	fill(int n, @NonNull Supplier<? extends T> s)	Returns a List containing n values supplied by a given Supplier s.
static <T> List<T>	fill(int n, T element)	Returns a List containing n times the given element
default List<T>	filter(@NonNull Predicate<? super T> predicate)	Returns a new traversable containing only the elements that satisfy the given predicate.
default <U> List<U>	flatMap(@NonNull Function<? super T, ? extends Iterable<? extends U>> mapper)	Transforms each element of this Traversable into an Iterable of elements and flattens the resulting iterables into a single Traversable.
default T	get(int index)	Returns the element at the specified index.
default <C> Map<C,List<T>>	groupBy(@NonNull Function<? super T, ? extends C> classifier)	Groups elements of this Traversable based on a classifier function.
default Iterator<List<T>>	grouped(int size)	Splits this Traversable into consecutive blocks of the given size.
default boolean	hasDefiniteSize()	Indicates whether this Traversable has a known finite size.
default int	indexOf(T element, int from)	Returns the index of the first occurrence of the given element, starting at the specified index, or -1 if this sequence does not contain the element.
default List<T>	init()	Returns all elements of this Traversable except the last one.
default Option<List<T>>	initOption()	Returns all elements of this Traversable except the last one, wrapped in an Option.
default List<T>	insert(int index, T element)	Returns a new sequence with the given element inserted at the specified index.
default List<T>	insertAll(int index, @NonNull Iterable<? extends T> elements)	Returns a new sequence with the given elements inserted at the specified index.
default List<T>	intersperse(T element)	Returns a new sequence where the given element is inserted between all elements of this sequence.
default boolean	isAsync()	A List is computed synchronously.
boolean	isEmpty()	Checks if this Traversable contains no elements.
default boolean	isLazy()	A List is computed eagerly.
default boolean	isTraversableAgain()	Checks if this Traversable can be traversed multiple times without side effects.
default T	last()	Returns the last element of this Traversable.
default int	lastIndexOf(T element, int end)	Returns the index of the last occurrence of the given element at or before the specified end index, or -1 if this sequence does not contain the element.
default List<T>	leftPadTo(int length, T element)	Returns a new sequence with this sequence padded on the left with the given element until the specified target length is reached.
int	length()	Returns the number of elements in this Traversable.
default <U> List<U>	map(@NonNull Function<? super T, ? extends U> mapper)	Transforms the elements of this Traversable to a new type, preserving order if defined.
default <U> List<U>	mapTo(U value)	Maps the underlying value to another fixed value.
default List<Void>	mapToVoid()	Maps the underlying value to Void
static <T> List<T>	narrow(List<? extends T> list)	Narrows a widened List<? extends T> to List<T> by performing a type-safe cast.
static <T> List<T>	of(T element)	Returns a singleton List, i.e.
static <T> List<T>	of(T @NonNull ... elements)	Creates a List of the given elements.
static List<Boolean>	ofAll(boolean @NonNull ... elements)	Creates a List from boolean values.
static List<Byte>	ofAll(byte @NonNull ... elements)	Creates a List from byte values.
static List<Character>	ofAll(char @NonNull ... elements)	Creates a List from char values.
static List<Double>	ofAll(double @NonNull ... elements)	Creates a List from double values.
static List<Float>	ofAll(float @NonNull ... elements)	Creates a List from float values.
static List<Integer>	ofAll(int @NonNull ... elements)	Creates a List from int values.
static List<Long>	ofAll(long @NonNull ... elements)	Creates a List from long values.
static List<Short>	ofAll(short @NonNull ... elements)	Creates a List from short values.
static <T> List<T>	ofAll(@NonNull Iterable<? extends T> elements)	Creates a List of the given elements.
static <T> List<T>	ofAll(@NonNull Stream<? extends T> javaStream)	Creates a List that contains the elements of the given Stream.
default List<T>	orElse(@NonNull Iterable<? extends T> other)	Returns this Traversable if it is non-empty; otherwise, returns the given alternative.
default List<T>	orElse(@NonNull Supplier<? extends Iterable<? extends T>> supplier)	Returns this Traversable if it is non-empty; otherwise, returns the result of evaluating the given supplier.
default List<T>	padTo(int length, T element)	Returns a new sequence with this sequence padded on the right with the given element until the specified target length is reached.
default Tuple2<List<T>,List<T>>	partition(@NonNull Predicate<? super T> predicate)	Splits this Traversable into two partitions according to a predicate.
default List<T>	patch(int from, @NonNull Iterable<? extends T> that, int replaced)	Returns a new sequence in which a slice of elements in this sequence is replaced by the elements of another sequence.
default T	peek()	Returns the head element without modifying the List.
default List<T>	peek(@NonNull Consumer<? super T> action)	Performs an action on the head element of this List.
default Option<T>	peekOption()	Returns the head element without modifying the List.
default List<List<T>>	permutations()	Returns all unique permutations of this sequence.
default List<T>	pop()	Removes the head element from this List.
default Tuple2<T,List<T>>	pop2()	Removes the head element from this List.
default Option<Tuple2<T,List<T>>>	pop2Option()	Removes the head element from this List.
default Option<List<T>>	popOption()	Removes the head element from this List.
default List<T>	prepend(T element)	Returns a new sequence with the given element prepended to this sequence.
default List<T>	prependAll(@NonNull Iterable<? extends T> elements)	Returns a new sequence with all given elements prepended to this sequence.
default List<T>	push(T element)	Pushes a new element on top of this List.
default List<T>	push(T @NonNull ... elements)	Pushes the given elements on top of this List.
default List<T>	pushAll(@NonNull Iterable<T> elements)	Pushes the given elements on top of this List.
static List<Character>	range(char from, char toExclusive)	Creates a List of char numbers starting from from, extending to toExclusive - 1.
static List<Integer>	range(int from, int toExclusive)	Creates a List of int numbers starting from from, extending to toExclusive - 1.
static List<Long>	range(long from, long toExclusive)	Creates a List of long numbers starting from from, extending to toExclusive - 1.
static List<Character>	rangeBy(char from, char toExclusive, int step)	Creates a List of char numbers starting from from, extending to toExclusive - 1, with step.
static List<Double>	rangeBy(double from, double toExclusive, double step)	Creates a List of double numbers starting from from, extending up to but not including toExclusive, with step.
static List<Integer>	rangeBy(int from, int toExclusive, int step)	Creates a List of int numbers starting from from, extending to toExclusive - 1, with step.
static List<Long>	rangeBy(long from, long toExclusive, long step)	Creates a List of long numbers starting from from, extending to toExclusive - 1, with step.
static List<Character>	rangeClosed(char from, char toInclusive)	Creates a List of char numbers starting from from, extending to toInclusive.
static List<Integer>	rangeClosed(int from, int toInclusive)	Creates a List of int numbers starting from from, extending to toInclusive.
static List<Long>	rangeClosed(long from, long toInclusive)	Creates a List of long numbers starting from from, extending to toInclusive.
static List<Character>	rangeClosedBy(char from, char toInclusive, int step)	Creates a List of char numbers starting from from, extending to toInclusive, with step.
static List<Double>	rangeClosedBy(double from, double toInclusive, double step)	Creates a List of double numbers starting from from, extending to toInclusive, with step.
static List<Integer>	rangeClosedBy(int from, int toInclusive, int step)	Creates a List of int numbers starting from from, extending to toInclusive, with step.
static List<Long>	rangeClosedBy(long from, long toInclusive, long step)	Creates a List of long numbers starting from from, extending to toInclusive, with step.
default List<T>	reject(@NonNull Predicate<? super T> predicate)	Returns a new traversable containing only the elements that do not satisfy the given predicate.
default List<T>	remove(T element)	Returns a new sequence with the first occurrence of the given element removed.
default List<T>	removeAll(@NonNull Iterable<? extends T> elements)	Returns a new sequence with all occurrences of the given elements removed.
default List<T>	removeAll(@NonNull Predicate<? super T> predicate)	Deprecated.
default List<T>	removeAll(T element)	Returns a new sequence with all occurrences of the given element removed.
default List<T>	removeAt(int index)	Returns a new sequence with the element at the specified position removed.
default List<T>	removeFirst(@NonNull Predicate<T> predicate)	Returns a new sequence with the first element that satisfies the given predicate removed.
default List<T>	removeLast(@NonNull Predicate<T> predicate)	Returns a new sequence with the last element that satisfies the given predicate removed.
default List<T>	replace(T currentElement, T newElement)	Replaces the first occurrence of currentElement with newElement, if it exists.
default List<T>	replaceAll(T currentElement, T newElement)	Replaces all occurrences of currentElement with newElement.
default List<T>	retainAll(@NonNull Iterable<? extends T> elements)	Retains only the elements from this Traversable that are contained in the given elements.
default List<T>	reverse()	Returns a new sequence with the order of elements reversed.
default List<T>	rotateLeft(int n)	Returns a new sequence with the elements circularly rotated to the left by the specified distance.
default List<T>	rotateRight(int n)	Returns a new sequence with the elements circularly rotated to the right by the specified distance.
default List<T>	scan(T zero, @NonNull BiFunction<? super T, ? super T, ? extends T> operation)	Computes a prefix scan of the elements of this Traversable.
default <U> List<U>	scanLeft(U zero, @NonNull BiFunction<? super U, ? super T, ? extends U> operation)	Produces a collection containing cumulative results of applying the operator from left to right.
default <U> List<U>	scanRight(U zero, @NonNull BiFunction<? super T, ? super U, ? extends U> operation)	Produces a collection containing cumulative results of applying the operator from right to left.
default List<T>	shuffle()	Returns a new sequence with the elements randomly shuffled.
default List<T>	slice(int beginIndex, int endIndex)	Returns a subsequence (slice) of this sequence, starting at beginIndex (inclusive) and ending at endIndex (exclusive).
default Iterator<List<T>>	slideBy(@NonNull Function<? super T, ?> classifier)	Partitions this Traversable into consecutive non-overlapping windows according to a classification function.
default Iterator<List<T>>	sliding(int size)	Slides a window of a given size over this Traversable with a step size of 1.
default Iterator<List<T>>	sliding(int size, int step)	Slides a window of a specific size with a given step over this Traversable.
default <U> List<T>	sortBy(@NonNull Comparator<? super U> comparator, Function<? super T, ? extends U> mapper)	Returns a new sequence sorted by comparing elements in a different domain defined by the given mapper, using the provided comparator.
default <U extends Comparable<? super U>> List<T>	sortBy(@NonNull Function<? super T, ? extends U> mapper)	Returns a new sequence sorted by comparing elements in a different domain defined by the given mapper.
default List<T>	sorted()	Returns a new sequence with elements sorted according to their natural order.
default List<T>	sorted(@NonNull Comparator<? super T> comparator)	Returns a new sequence with elements sorted according to the given Comparator.
default Tuple2<List<T>,List<T>>	span(@NonNull Predicate<? super T> predicate)	Splits this Traversable into a prefix and remainder according to the given predicate.
default Tuple2<List<T>,List<T>>	splitAt(int n)	Splits this sequence at the specified index.
default Tuple2<List<T>,List<T>>	splitAt(@NonNull Predicate<? super T> predicate)	Splits this sequence at the first element satisfying the given predicate.
default Tuple2<List<T>,List<T>>	splitAtInclusive(@NonNull Predicate<? super T> predicate)	Splits this sequence at the first element satisfying the given predicate, including the element in the first part.
default String	stringPrefix()	Returns the name of this Value type, which is used by toString().
default List<T>	subSequence(int beginIndex)	Returns a Seq that is a subsequence of this sequence, starting from the specified beginIndex and extending to the end of this sequence.
default List<T>	subSequence(int beginIndex, int endIndex)	Returns a Seq that is a subsequence of this sequence, starting from the specified beginIndex (inclusive) and ending at endIndex (exclusive).
static <T> List<T>	tabulate(int n, @NonNull Function<? super Integer, ? extends T> f)	Returns a List containing n values of a given Function f over a range of integer values from 0 to n - 1.
List<T>	tail()	Returns a new Traversable without its first element.
default Option<List<T>>	tailOption()	Returns a new Traversable without its first element as an Option.
default List<T>	take(int n)	Returns the first n elements of this Traversable, or all elements if n exceeds the length.
default List<T>	takeRight(int n)	Returns the last n elements of this Traversable, or all elements if n exceeds the length.
default List<T>	takeRightUntil(@NonNull Predicate<? super T> predicate)	Takes elements from the end of the sequence until an element satisfies the given predicate.
default List<T>	takeRightWhile(@NonNull Predicate<? super T> predicate)	Takes elements from the end of the sequence while the given predicate holds.
default List<T>	takeUntil(@NonNull Predicate<? super T> predicate)	Takes elements from this Traversable until the given predicate holds for an element.
default List<T>	takeWhile(@NonNull Predicate<? super T> predicate)	Takes elements from this Traversable while the given predicate holds.
default <U> U	transform(@NonNull Function<? super List<T>, ? extends U> f)	Transforms this List.
static <T> List<List<T>>	transpose(@NonNull List<List<T>> matrix)	Transposes the rows and columns of a List matrix.
static <T> List<T>	unfold(T seed, @NonNull Function<? super T, Option<Tuple2<? extends T, ? extends T>>> f)	Creates a list from a seed value and a function.
static <T,U> List<U>	unfoldLeft(T seed, @NonNull Function<? super T, Option<Tuple2<? extends T, ? extends U>>> f)	Creates a list from a seed value and a function.
static <T,U> List<U>	unfoldRight(T seed, @NonNull Function<? super T, @NonNull Option<Tuple2<? extends U, ? extends T>>> f)	Creates a list from a seed value and a function.
default <T1,T2> Tuple2<List<T1>,List<T2>>	unzip(@NonNull Function<? super T, Tuple2<? extends T1, ? extends T2>> unzipper)	Unzips the elements of this Traversable by mapping each element to a pair and splitting them into two separate Traversable collections.
default <T1,T2,T3> Tuple3<List<T1>,List<T2>,List<T3>>	unzip3(@NonNull Function<? super T, Tuple3<? extends T1, ? extends T2, ? extends T3>> unzipper)	Unzips the elements of this Traversable by mapping each element to a triple and splitting them into three separate Traversable collections.
default List<T>	update(int index, @NonNull Function<? super T, ? extends T> updater)	Returns a new Seq with the element at the specified index updated using the given function.
default List<T>	update(int index, T element)	Returns a new Seq with the element at the specified index replaced by the given value.
default <U> List<Tuple2<T,U>>	zip(@NonNull Iterable<? extends U> that)	Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable.
default <U> List<Tuple2<T,U>>	zipAll(@NonNull Iterable<? extends U> that, T thisElem, U thatElem)	Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable, filling in placeholder elements when one collection is shorter than the other.
default <U,R> List<R>	zipWith(@NonNull Iterable<? extends U> that, BiFunction<? super T, ? super U, ? extends R> mapper)	Returns a Traversable by combining elements of this Traversable with elements of another Iterable using a mapping function.
default List<Tuple2<T,Integer>>	zipWithIndex()	Zips this Traversable with its indices, starting at 0.
default <U> List<U>	zipWithIndex(@NonNull BiFunction<? super T, ? super Integer, ? extends U> mapper)	Zips this Traversable with its indices and maps the resulting pairs using the provided mapper.

Methods inherited from interface Foldable

fold, reduce, reduceOption

Methods inherited from interface Function1

andThen, arity, compose, compose1, curried, isMemoized, memoized, partial, reversed, tupled

Methods inherited from interface LinearSeq

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

Methods inherited from interface 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 Traversable

arrangeBy, average, containsAll, count, equals, existsUnique, find, findLast, foldLeft, forEachWithIndex, get, hashCode, head, headOption, isDistinct, 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 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

The serial version UID for serialization.

See Also:

• Constant Field Values

Method Details

collector

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

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

Type Parameters:

T - Component type of the List.

Returns:

A io.vavr.collection.List Collector.

empty

static <T> List<T> empty()

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

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

Type Parameters:

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

Returns:

The empty list.

isAsync

default boolean isAsync()

A List is computed synchronously.

Specified by:

isAsync in interface Value<T>

Returns:

false

isEmpty

boolean isEmpty()

Description copied from interface: Traversable

Checks if this Traversable contains no elements.

Specified by:

isEmpty in interface Traversable<T>

Specified by:

isEmpty in interface Value<T>

Returns:

true if empty, false otherwise

isLazy

default boolean isLazy()

A List is computed eagerly.

Specified by:

isLazy in interface Value<T>

Returns:

false

narrow

static <T> List<T> narrow(List<? extends T> list)

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

Type Parameters:

T - Component type of the List.

Parameters:

list - A List.

Returns:

the given list instance as narrowed type List<T>.

of

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

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

Type Parameters:

T - The component type

Parameters:

element - An element.

Returns:

A new List instance containing the given element

of

@SafeVarargs
static <T> List<T> of(T @NonNull ... elements)

Creates a List of the given elements.

  List.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 List.

Parameters:

elements - Zero or more elements.

Returns:

A list containing the given elements in the same order.

Throws:

NullPointerException - if elements is null

ofAll

static <T> List<T> ofAll(@NonNull Iterable<? extends T> elements)

Creates a List of the given elements.

The resulting list has the same iteration order as the given iterable of elements if the iteration order of the elements is stable.

Type Parameters:

T - Component type of the List.

Parameters:

elements - An Iterable of elements.

Returns:

A list containing the given elements in the same order.

Throws:

NullPointerException - if elements is null

ofAll

static <T> List<T> ofAll(@NonNull Stream<? extends T> javaStream)

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

Type Parameters:

T - Component type of the Stream.

Parameters:

javaStream - A Stream

Returns:

A List containing the given elements in the same order.

ofAll

static List<Boolean> ofAll(boolean @NonNull ... elements)

Creates a List from boolean values.

Parameters:

elements - boolean values

Returns:

A new List of Boolean values

Throws:

NullPointerException - if elements is null

ofAll

static List<Byte> ofAll(byte @NonNull ... elements)

Creates a List from byte values.

Parameters:

elements - byte values

Returns:

A new List of Byte values

Throws:

NullPointerException - if elements is null

ofAll

static List<Character> ofAll(char @NonNull ... elements)

Creates a List from char values.

Parameters:

elements - char values

Returns:

A new List of Character values

Throws:

NullPointerException - if elements is null

ofAll

static List<Double> ofAll(double @NonNull ... elements)

Creates a List from double values.

Parameters:

elements - double values

Returns:

A new List of Double values

Throws:

NullPointerException - if elements is null

ofAll

static List<Float> ofAll(float @NonNull ... elements)

Creates a List from float values.

Parameters:

elements - a float values

Returns:

A new List of Float values

Throws:

NullPointerException - if elements is null

ofAll

static List<Integer> ofAll(int @NonNull ... elements)

Creates a List from int values.

Parameters:

elements - int values

Returns:

A new List of Integer values

Throws:

NullPointerException - if elements is null

ofAll

static List<Long> ofAll(long @NonNull ... elements)

Creates a List from long values.

Parameters:

elements - long values

Returns:

A new List of Long values

Throws:

NullPointerException - if elements is null

ofAll

static List<Short> ofAll(short @NonNull ... elements)

Creates a List from short values.

Parameters:

elements - short values

Returns:

A new List of Short values

Throws:

NullPointerException - if elements is null

tabulate

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

Returns a List 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 List

Parameters:

n - The number of elements in the List

f - The Function computing element values

Returns:

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

Throws:

NullPointerException - if f is null

fill

static <T> List<T> fill(int n,
 @NonNull Supplier<? extends T> s)

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

Type Parameters:

T - Component type of the List

Parameters:

n - The number of elements in the List

s - The Supplier computing element values

Returns:

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

Throws:

NullPointerException - if s is null

fill

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

Returns a List containing n times the given element

Type Parameters:

T - Component type of the List

Parameters:

n - The number of elements in the List

element - The element

Returns:

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

range

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

Creates a List of char numbers starting from from, extending to toExclusive - 1.

Examples:

List.range('a', 'a')  // = List()
List.range('c', 'a')  // = List()
List.range('a', 'd')  // = List('a', 'b', 'c')

Parameters:

from - the first char

toExclusive - the last char + 1

Returns:

a range of char values as specified or the empty range if from >= toExclusive

rangeBy

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

Creates a List of char numbers starting from from, extending to toExclusive - 1, with step.

Examples:

List.rangeBy('a', 'c', 1)  // = List('a', 'b')
List.rangeBy('a', 'd', 2)  // = List('a', 'c')
List.rangeBy('d', 'a', -2) // = List('d', 'b')
List.rangeBy('d', 'a', 2)  // = List()

Parameters:

from - the first char

toExclusive - the last char + 1

step - the step

Returns:

a range of char values as specified or the empty range if
from >= toExclusive and step > 0 or
from <= toExclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

rangeBy

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

Creates a List of double numbers starting from from, extending up to but not including toExclusive, with step.

Examples:

List.rangeBy(1.0, 3.0, 1.0)  // = List(1.0, 2.0)
List.rangeBy(1.0, 4.0, 2.0)  // = List(1.0, 3.0)
List.rangeBy(4.0, 1.0, -2.0) // = List(4.0, 2.0)
List.rangeBy(4.0, 1.0, 2.0)  // = List()

Parameters:

from - the first double

toExclusive - the upper bound (exclusive)

step - the step

Returns:

a range of double values as specified or the empty range if
from >= toExclusive and step > 0 or
from <= toExclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

range

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

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

Examples:

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

Parameters:

from - the first number

toExclusive - the last number + 1

Returns:

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

rangeBy

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

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

Examples:

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

Parameters:

from - the first number

toExclusive - the last number + 1

step - the step

Returns:

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

Throws:

IllegalArgumentException - if step is zero

range

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

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

Examples:

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

Parameters:

from - the first number

toExclusive - the last number + 1

Returns:

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

rangeBy

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

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

Examples:

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

Parameters:

from - the first number

toExclusive - the last number + 1

step - the step

Returns:

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

Throws:

IllegalArgumentException - if step is zero

rangeClosed

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

Creates a List of char numbers starting from from, extending to toInclusive.

Examples:

List.rangeClosed('a', 'a')  // = List('a')
List.rangeClosed('c', 'a')  // = List()
List.rangeClosed('a', 'd')  // = List('a', 'b', 'c', 'd')

Parameters:

from - the first char

toInclusive - the last char

Returns:

a range of char values as specified or the empty range if from > toInclusive

rangeClosedBy

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

Creates a List of char numbers starting from from, extending to toInclusive, with step.

Examples:

List.rangeClosedBy('a', 'c', 1)  // = List('a', 'b', 'c')
List.rangeClosedBy('a', 'd', 2)  // = List('a', 'c')
List.rangeClosedBy('d', 'a', -2) // = List('d', 'b')
List.rangeClosedBy('d', 'a', 2)  // = List()

Parameters:

from - the first char

toInclusive - the last char

step - the step

Returns:

a range of char values as specified or the empty range if
from > toInclusive and step > 0 or
from < toInclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

rangeClosedBy

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

Creates a List of double numbers starting from from, extending to toInclusive, with step.

Examples:

List.rangeClosedBy(1.0, 3.0, 1.0)  // = List(1.0, 2.0, 3.0)
List.rangeClosedBy(1.0, 4.0, 2.0)  // = List(1.0, 3.0)
List.rangeClosedBy(4.0, 1.0, -2.0) // = List(4.0, 2.0)
List.rangeClosedBy(4.0, 1.0, 2.0)  // = List()

Parameters:

from - the first double

toInclusive - the upper bound (inclusive)

step - the step

Returns:

a range of double values as specified or the empty range if
from > toInclusive and step > 0 or
from < toInclusive and step < 0

Throws:

IllegalArgumentException - if step is zero

rangeClosed

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

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

Examples:

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

Parameters:

from - the first number

toInclusive - the last number

Returns:

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

rangeClosedBy

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

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

Examples:

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

Parameters:

from - the first number

toInclusive - the last number

step - the step

Returns:

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

Throws:

IllegalArgumentException - if step is zero

rangeClosed

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

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

Examples:

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

Parameters:

from - the first number

toInclusive - the last number

Returns:

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

rangeClosedBy

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

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

Examples:

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

Parameters:

from - the first number

toInclusive - the last number

step - the step

Returns:

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

Throws:

IllegalArgumentException - if step is zero

transpose

static <T> List<List<T>> transpose(@NonNull List<List<T>> matrix)

Transposes the rows and columns of a List matrix.

Type Parameters:

T - matrix element type

Parameters:

matrix - to be transposed.

Returns:

a transposed List matrix.

Throws:

IllegalArgumentException - if the row lengths of matrix differ.

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

unfoldRight

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

Creates a list 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 list, otherwise Some Tuple of the element for the next call and the value to add to the resulting list.

Example:

List.unfoldRight(10, x -> x == 0
            ? Option.none()
            : Option.of(new Tuple2<>(x, x-1)));
// List(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 list with the values built up by the iteration

Throws:

NullPointerException - if f is null

unfoldLeft

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

Creates a list 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 list, otherwise Some Tuple of the value to add to the resulting list and the element for the next call.

Example:

List.unfoldLeft(10, x -> x == 0
            ? Option.none()
            : Option.of(new Tuple2<>(x-1, x)));
// List(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 list with the values built up by the iteration

Throws:

NullPointerException - if f is null

unfold

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

Creates a list 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 list, otherwise Some Tuple of the value to add to the resulting list and the element for the next call.

Example:

List.unfold(10, x -> x == 0
            ? Option.none()
            : Option.of(new Tuple2<>(x-1, x)));
// List(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 list with the values built up by the iteration

Throws:

NullPointerException - if f is null

append

default List<T> append(T element)

Description copied from interface: Seq

Returns a new sequence with the given element appended at the end.

Specified by:

append in interface LinearSeq<T>

Specified by:

append in interface Seq<T>

Parameters:

element - the element to append

Returns:

a new Seq containing all elements of this sequence followed by the given element

appendAll

default List<T> appendAll(@NonNull Iterable<? extends T> elements)

Description copied from interface: Seq

Returns a new sequence with all elements from the given Iterable appended at the end of this sequence.

Specified by:

appendAll in interface LinearSeq<T>

Specified by:

appendAll in interface Seq<T>

Parameters:

elements - the elements to append; must not be null

Returns:

a new Seq containing all elements of this sequence followed by the given elements

asJava

@GwtIncompatible
default List<T> asJava()

Description copied from interface: Seq

Returns an immutable List view of this Seq. Any attempt to modify the view (e.g., via mutator methods) will throw UnsupportedOperationException at runtime.

This is a view, not a copy. Compared to conversion methods like toJava*():

• Creating the view is O(1) (constant time), whereas conversions take O(n), with n = collection size.
• Operations on the view have the same performance characteristics as the underlying persistent Vavr collection, while converted collections behave like standard Java collections.

Note: the immutable Java list view throws UnsupportedOperationException before checking method arguments, which may differ from standard Java behavior.

Specified by:

asJava in interface Seq<T>

Returns:

an immutable List view of this sequence

asJava

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

Description copied from interface: Seq

Creates an immutable List view of this Seq and passes it to the given action.

The view is immutable: any attempt to modify it will throw UnsupportedOperationException at runtime.

Specified by:

asJava in interface LinearSeq<T>

Specified by:

asJava in interface Seq<T>

Parameters:

action - a side-effecting operation that receives an immutable java.util.List view

Returns:

this sequence

See Also:

• Seq.asJava()

asJavaMutable

@GwtIncompatible
default List<T> asJavaMutable()

Description copied from interface: Seq

Returns a mutable List view of this Seq. All standard mutator methods of the List interface are supported and modify the underlying view.

Unlike Seq.asJava(), this view allows modifications, but the performance characteristics correspond to the underlying persistent Vavr collection.

Specified by:

asJavaMutable in interface Seq<T>

Returns:

a mutable List view of this sequence

See Also:

• Seq.asJava()

asJavaMutable

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

Description copied from interface: Seq

Creates a mutable List view of this Seq and passes it to the given action.

The view supports all standard mutator methods. The result of the action determines what is returned:

• If only read operations are performed, this instance is returned.
• If any write operations are performed, a new Seq reflecting those changes is returned.

Specified by:

asJavaMutable in interface LinearSeq<T>

Specified by:

asJavaMutable in interface Seq<T>

Parameters:

action - a side-effecting operation that receives a mutable java.util.List view

Returns:

this sequence or a new sequence reflecting modifications made through the view

See Also:

• Seq.asJavaMutable()

collect

default <R> List<R> collect(@NonNull PartialFunction<? super T, ? extends R> partialFunction)

Description copied from interface: Traversable

Applies a PartialFunction to all elements that are defined for it and collects the results.

For each element in iteration order, the function is first tested:

partialFunction.isDefinedAt(element)

If true, the element is mapped to type R:

R newElement = partialFunction.apply(element)

Note: If this Traversable is ordered (i.e., extends Ordered), the caller must ensure that the resulting elements are comparable (i.e., implement 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 type of elements in the resulting Traversable

Parameters:

partialFunction - a function that may not be defined for all elements of this traversable

Returns:

a new Traversable containing the results of applying the partial function

combinations

default List<List<T>> combinations()

Description copied from interface: Seq

Returns a sequence containing all combinations of elements from this sequence, for all sizes from 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:

a sequence of sequences representing all combinations of this sequence's elements

combinations

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

Description copied from interface: Seq

Returns all subsets of this sequence containing exactly k distinct elements, i.e., the k-combinations of this sequence.

Specified by:

combinations in interface LinearSeq<T>

Specified by:

combinations in interface Seq<T>

Parameters:

k - the size of each subset

Returns:

a sequence of sequences representing all k-element combinations

See Also:

• Combination

crossProduct

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

Description copied from interface: Seq

Returns the n-ary Cartesian power (cross product) of this sequence. Each element of the resulting iterator is a sequence of length power, containing all possible combinations of elements from this sequence.

Example for power = 2:

// Result: [(A,A), (A,B), (A,C), ..., (B,A), (B,B), ..., (Z,Y), (Z,Z)]
CharSeq.rangeClosed('A', 'Z').crossProduct(2);

If power is negative, the result is an empty iterator:

// Result: ()
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:

an Iterator over sequences representing the Cartesian power of this sequence

distinct

default List<T> distinct()

Description copied from interface: Traversable

Returns a new Traversable containing the elements of this instance with all duplicates removed. Element equality is determined 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 without duplicate elements

distinctBy

default List<T> distinctBy(@NonNull Comparator<? super T> comparator)

Description copied from interface: Traversable

Returns a new Traversable containing the elements of this instance without duplicates, as determined by 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 used to determine equality of elements

Returns:

a new Traversable with duplicates removed

distinctBy

default <U> List<T> distinctBy(@NonNull Function<? super T, ? extends U> keyExtractor)

Description copied from interface: Traversable

Returns a new Traversable containing the elements of this instance without duplicates, based on keys extracted from elements using keyExtractor.

The first occurrence of each key is retained in the resulting sequence.

Specified by:

distinctBy in interface LinearSeq<T>

Specified by:

distinctBy in interface Seq<T>

Specified by:

distinctBy in interface Traversable<T>

Type Parameters:

U - the type of key

Parameters:

keyExtractor - a function to extract keys for determining uniqueness

Returns:

a new Traversable with duplicates removed based on keys

distinctByKeepLast

default List<T> distinctByKeepLast(@NonNull Comparator<? super T> comparator)

Description copied from interface: Seq

Returns a sequence with duplicate elements removed, as determined by the provided comparator. When duplicates are found, the **last occurrence** of each element is retained.

Specified by:

distinctByKeepLast in interface LinearSeq<T>

Specified by:

distinctByKeepLast in interface Seq<T>

Parameters:

comparator - a comparator defining equality between elements

Returns:

a new sequence with duplicates removed, keeping the last occurrence of each element

distinctByKeepLast

default <U> List<T> distinctByKeepLast(@NonNull Function<? super T, ? extends U> keyExtractor)

Description copied from interface: Seq

Returns a sequence with duplicates removed based on a key extracted from each element. The key is obtained via the provided keyExtractor function. When duplicates are found, the **last occurrence** of each element for a given key is retained.

Specified by:

distinctByKeepLast in interface LinearSeq<T>

Specified by:

distinctByKeepLast in interface Seq<T>

Type Parameters:

U - the type of the key used for determining uniqueness

Parameters:

keyExtractor - a function extracting a key from each element for uniqueness comparison

Returns:

a new sequence of elements distinct by the extracted key, keeping the last occurrence

drop

default List<T> drop(int n)

Description copied from interface: Traversable

Returns a new Traversable without the first n elements, or an empty instance if this contains fewer than n elements.

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 excluding the first n elements

dropUntil

default List<T> dropUntil(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a new Traversable starting from the first element that satisfies the given predicate, dropping all preceding elements.

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 on each element

Returns:

a new instance starting from the first element matching the predicate

dropWhile

default List<T> dropWhile(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a new Traversable starting from the first element that does not satisfy the given predicate, dropping all preceding elements.

This is equivalent to dropUntil(predicate.negate()), which is useful for method references that 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 on each element

Returns:

a new instance starting from the first element not matching the predicate

dropRight

default List<T> dropRight(int n)

Description copied from interface: Traversable

Returns a new Traversable without the last n elements, or an empty instance if this contains fewer than n elements.

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 from the end

Returns:

a new instance excluding the last n elements

dropRightUntil

default List<T> dropRightUntil(@NonNull Predicate<? super T> predicate)

Description copied from interface: Seq

Drops elements from the end of the sequence until an element satisfies the given predicate. The returned sequence includes the last element that satisfies the predicate.

Specified by:

dropRightUntil in interface LinearSeq<T>

Specified by:

dropRightUntil in interface Seq<T>

Parameters:

predicate - a condition to test elements, starting from the end

Returns:

a new sequence containing all elements up to and including the last element that satisfies the predicate

dropRightWhile

default List<T> dropRightWhile(@NonNull Predicate<? super T> predicate)

Description copied from interface: Seq

Drops elements from the end of the sequence while the given predicate holds.

This is equivalent to dropRightUntil(predicate.negate()). Useful when using method references that cannot be negated directly.

Specified by:

dropRightWhile in interface LinearSeq<T>

Specified by:

dropRightWhile in interface Seq<T>

Parameters:

predicate - a condition to test elements, starting from the end

Returns:

a new sequence containing all elements up to and including the last element that does not satisfy the predicate

filter

default List<T> filter(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a new traversable containing only the elements that 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 - the condition to test elements

Returns:

a traversable with elements matching the predicate

reject

default List<T> reject(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Returns a new traversable containing only the elements that do not satisfy the given predicate.

This 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 - the condition to test elements

Returns:

a traversable with elements not matching the predicate

flatMap

default <U> List<U> flatMap(@NonNull Function<? super T, ? extends Iterable<? extends U>> mapper)

Description copied from interface: Traversable

Transforms each element of this Traversable into an Iterable of elements and flattens the resulting iterables into a single 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 type of elements in the resulting Traversable

Parameters:

mapper - a function mapping elements to iterables

Returns:

a new Traversable containing all elements produced by applying mapper and flattening

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 - the position of the element to retrieve

Returns:

the element at the given index

groupBy

default <C> Map<C,List<T>> groupBy(@NonNull Function<? super T, ? extends C> classifier)

Description copied from interface: Traversable

Groups elements of this Traversable based on a classifier function.

Specified by:

groupBy in interface LinearSeq<T>

Specified by:

groupBy in interface Seq<T>

Specified by:

groupBy in interface Traversable<T>

Type Parameters:

C - The type of the group keys

Parameters:

classifier - A function that assigns each element to a group

Returns:

A map where each key corresponds to a group of elements

See Also:

• Traversable.arrangeBy(Function)

grouped

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

Description copied from interface: Traversable

Splits this Traversable into consecutive blocks of the given size.

Let length be the number of elements in this Traversable:

• If empty, the resulting Iterator is empty.
• If size <= length, the resulting Iterator contains length / size blocks of size size and possibly a final smaller block of size length % size.
• If size > length, the resulting Iterator contains a single 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]]

Note: grouped(size) is equivalent to 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 - the block size; must be positive

Returns:

an Iterator over blocks of elements

hasDefiniteSize

default boolean hasDefiniteSize()

Description copied from interface: Traversable

Indicates whether this Traversable has a known finite size.

This should typically be implemented by concrete classes, not interfaces.

Specified by:

hasDefiniteSize in interface Traversable<T>

Returns:

true if the number of elements is finite and known, 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, starting at the specified index, or -1 if this sequence does not contain the element.

Specified by:

indexOf in interface Seq<T>

Parameters:

element - the element to search for

from - the starting index for the search

Returns:

the index of the first occurrence at or after from, or -1 if not found

init

default List<T> init()

Description copied from interface: Traversable

Returns all elements of this Traversable except the last one.

This is the dual of Traversable.tail().

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<List<T>> initOption()

Description copied from interface: Traversable

Returns all elements of this Traversable except the last one, wrapped in an Option.

This is the dual of Traversable.tailOption().

Specified by:

initOption in interface LinearSeq<T>

Specified by:

initOption in interface Seq<T>

Specified by:

initOption in interface Traversable<T>

Returns:

Some(traversable) if non-empty, or None if this Traversable is empty

length

int length()

Description copied from interface: Traversable

Returns the number of elements in this Traversable.

Equivalent to Traversable.size().

Specified by:

length in interface Traversable<T>

Returns:

the number of elements

insert

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

Description copied from interface: Seq

Returns a new sequence with the given element inserted at the specified index.

Specified by:

insert in interface LinearSeq<T>

Specified by:

insert in interface Seq<T>

Parameters:

index - the position at which to insert the element

element - the element to insert

Returns:

a new Seq with the element inserted

insertAll

default List<T> insertAll(int index,
 @NonNull Iterable<? extends T> elements)

Description copied from interface: Seq

Returns a new sequence with the given elements inserted at the specified index.

Specified by:

insertAll in interface LinearSeq<T>

Specified by:

insertAll in interface Seq<T>

Parameters:

index - the position at which to insert the elements

elements - the elements to insert; must not be null

Returns:

a new Seq with the elements inserted

intersperse

default List<T> intersperse(T element)

Description copied from interface: Seq

Returns a new sequence where the given element is inserted between all elements of this sequence.

Specified by:

intersperse in interface LinearSeq<T>

Specified by:

intersperse in interface Seq<T>

Parameters:

element - the element to intersperse

Returns:

a new Seq with the element interspersed

isTraversableAgain

default boolean isTraversableAgain()

Description copied from interface: Traversable

Checks if this Traversable can be traversed multiple times without side effects.

Implementations should provide the correct behavior; this is not meant for interfaces alone.

Specified by:

isTraversableAgain in interface Traversable<T>

Returns:

true if this Traversable is guaranteed to be repeatably traversable, false otherwise

last

default T last()

Description copied from interface: Traversable

Returns the last element of this Traversable.

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 at or before the specified end index, or -1 if this sequence does not contain the element.

Specified by:

lastIndexOf in interface Seq<T>

Parameters:

element - the element to search for

end - the maximum index to consider

Returns:

the index of the last occurrence at or before end, or -1 if not found

map

default <U> List<U> map(@NonNull Function<? super T, ? extends U> mapper)

Description copied from interface: Traversable

Transforms the elements of this Traversable to a new type, preserving order if defined.

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 - the target element type

Parameters:

mapper - a mapping function

Returns:

a new Traversable containing the mapped elements

mapTo

default <U> List<U> mapTo(U value)

Description copied from interface: Value

Maps the underlying value to another fixed value.

Specified by:

mapTo in interface LinearSeq<T>

Specified by:

mapTo in interface Seq<T>

Specified by:

mapTo in interface Traversable<T>

Specified by:

mapTo in interface Value<T>

Type Parameters:

U - The new component type

Parameters:

value - value to replace the contents with

Returns:

A new value

mapToVoid

default List<Void> mapToVoid()

Description copied from interface: Value

Maps the underlying value to Void

Specified by:

mapToVoid in interface LinearSeq<T>

Specified by:

mapToVoid in interface Seq<T>

Specified by:

mapToVoid in interface Traversable<T>

Specified by:

mapToVoid in interface Value<T>

Returns:

A new value of type Void

orElse

default List<T> orElse(@NonNull Iterable<? extends T> other)

Description copied from interface: Traversable

Returns this Traversable if it is non-empty; otherwise, returns the given 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 to return if this is empty

Returns:

this Traversable if non-empty, otherwise other

orElse

default List<T> orElse(@NonNull Supplier<? extends Iterable<? extends T>> supplier)

Description copied from interface: Traversable

Returns this Traversable if it is non-empty; otherwise, returns the result of evaluating the given supplier.

Specified by:

orElse in interface LinearSeq<T>

Specified by:

orElse in interface Seq<T>

Specified by:

orElse in interface Traversable<T>

Parameters:

supplier - a supplier of an alternative Traversable if this is empty

Returns:

this Traversable if non-empty, otherwise the result of supplier.get()

padTo

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

Description copied from interface: Seq

Returns a new sequence with this sequence padded on the right with the given element until the specified target length is reached.

Note: Lazily-evaluated sequences may need to process all elements to determine the overall length.

Specified by:

padTo in interface LinearSeq<T>

Specified by:

padTo in interface Seq<T>

Parameters:

length - the target length of the resulting sequence

element - the element to append as padding

Returns:

a new Seq consisting of this sequence followed by the minimal number of occurrences of element to reach at least length

leftPadTo

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

Description copied from interface: Seq

Returns a new sequence with this sequence padded on the left with the given element until the specified target length is reached.

Note: Lazily-evaluated sequences may need to process all elements to determine the overall length.

Specified by:

leftPadTo in interface Seq<T>

Parameters:

length - the target length of the resulting sequence

element - the element to prepend as padding

Returns:

a new Seq consisting of this sequence prepended by the minimal number of occurrences of element to reach at least length

patch

default List<T> patch(int from,
 @NonNull Iterable<? extends T> that,
 int replaced)

Description copied from interface: Seq

Returns a new sequence in which a slice of elements in this sequence is replaced by the elements of another sequence.

Specified by:

patch in interface LinearSeq<T>

Specified by:

patch in interface Seq<T>

Parameters:

from - the starting index of the slice to be replaced

that - the sequence of elements to insert; must not be null

replaced - the number of elements to remove from this sequence starting at from

Returns:

a new Seq with the specified slice replaced

partition

default Tuple2<List<T>,List<T>> partition(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Splits this Traversable into two partitions according to a predicate.

The first partition contains all elements that satisfy the predicate, and the second contains all elements that do not. The original iteration order is preserved.

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 used to classify elements

Returns:

a Tuple2 containing the two resulting Traversable instances

peek

default T peek()

Returns the head element without modifying the List.

Returns:

the first element

Throws:

NoSuchElementException - if this List is empty

peekOption

default Option<T> peekOption()

Returns the head element without modifying the List.

Returns:

None if this List is empty, otherwise a Some containing the head element

peek

default List<T> peek(@NonNull Consumer<? super T> action)

Performs an action on the head element of this List.

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 - A Consumer

Returns:

this List

permutations

default List<List<T>> permutations()

Description copied from interface: Seq

Returns all unique permutations of this sequence.

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:

a sequence of all unique permutations of this sequence

pop

default List<T> pop()

Removes the head element from this List.

Returns:

the elements of this List without the head element

Throws:

NoSuchElementException - if this List is empty

popOption

default Option<List<T>> popOption()

Removes the head element from this List.

Returns:

None if this List is empty, otherwise a Some containing the elements of this List without the head element

pop2

default Tuple2<T,List<T>> pop2()

Removes the head element from this List.

Returns:

a tuple containing the head element and the remaining elements of this List

Throws:

NoSuchElementException - if this List is empty

pop2Option

default Option<Tuple2<T,List<T>>> pop2Option()

Removes the head element from this List.

Returns:

None if this List is empty, otherwise Some Tuple containing the head element and the remaining elements of this List

prepend

default List<T> prepend(T element)

Description copied from interface: Seq

Returns a new sequence with the given element prepended to this sequence.

Specified by:

prepend in interface LinearSeq<T>

Specified by:

prepend in interface Seq<T>

Parameters:

element - the element to prepend

Returns:

a new Seq with the element added at the front

prependAll

default List<T> prependAll(@NonNull Iterable<? extends T> elements)

Description copied from interface: Seq

Returns a new sequence with all given elements prepended to this sequence.

Specified by:

prependAll in interface LinearSeq<T>

Specified by:

prependAll in interface Seq<T>

Parameters:

elements - the elements to prepend; must not be null

Returns:

a new Seq with the elements added at the front

push

default List<T> push(T element)

Pushes a new element on top of this List.

Parameters:

element - The new element

Returns:

a new List instance, containing the new element on top of this List

push

default List<T> push(T @NonNull ... elements)

Pushes the given elements on top of this List. A List has LIFO order, i.e. the last of the given elements is the first which will be retrieved.

Parameters:

elements - Elements, may be empty

Returns:

a new List instance, containing the new elements on top of this List

Throws:

NullPointerException - if elements is null

pushAll

default List<T> pushAll(@NonNull Iterable<T> elements)

Pushes the given elements on top of this List. A List has LIFO order, i.e. the last of the given elements is the first which will be retrieved.

Parameters:

elements - An Iterable of elements, may be empty

Returns:

a new List instance, containing the new elements on top of this List

Throws:

NullPointerException - if elements is null

remove

default List<T> remove(T element)

Description copied from interface: Seq

Returns a new sequence with the first occurrence of the given element removed.

Specified by:

remove in interface LinearSeq<T>

Specified by:

remove in interface Seq<T>

Parameters:

element - the element to remove

Returns:

a new Seq without the first occurrence of the element

removeFirst

default List<T> removeFirst(@NonNull Predicate<T> predicate)

Description copied from interface: Seq

Returns a new sequence with the first element that satisfies the given predicate removed.

Specified by:

removeFirst in interface LinearSeq<T>

Specified by:

removeFirst in interface Seq<T>

Parameters:

predicate - the predicate used to identify the element to remove; must not be null

Returns:

a new Seq without the first matching element

removeLast

default List<T> removeLast(@NonNull Predicate<T> predicate)

Description copied from interface: Seq

Returns a new sequence with the last element that satisfies the given predicate removed.

Specified by:

removeLast in interface LinearSeq<T>

Specified by:

removeLast in interface Seq<T>

Parameters:

predicate - the predicate used to identify the element to remove; must not be null

Returns:

a new Seq without the last matching element

removeAt

default List<T> removeAt(int index)

Description copied from interface: Seq

Returns a new sequence with the element at the specified position removed. Subsequent elements are shifted to the left (indices decreased by one).

Specified by:

removeAt in interface LinearSeq<T>

Specified by:

removeAt in interface Seq<T>

Parameters:

index - the position of the element to remove

Returns:

a new Seq without the element at the specified index

removeAll

default List<T> removeAll(T element)

Description copied from interface: Seq

Returns a new sequence with all occurrences of the given element removed.

Specified by:

removeAll in interface LinearSeq<T>

Specified by:

removeAll in interface Seq<T>

Parameters:

element - the element to remove

Returns:

a new Seq without any occurrences of the element

removeAll

default List<T> removeAll(@NonNull Iterable<? extends T> elements)

Description copied from interface: Seq

Returns a new sequence with all occurrences of the given elements removed.

Specified by:

removeAll in interface LinearSeq<T>

Specified by:

removeAll in interface Seq<T>

Parameters:

elements - the elements to remove; must not be null

Returns:

a new Seq without any of the given elements

removeAll

@Deprecated
default List<T> removeAll(@NonNull 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 List<T> replace(T currentElement,
 T newElement)

Description copied from interface: Traversable

Replaces the first occurrence of currentElement with newElement, if it exists.

Specified by:

replace in interface LinearSeq<T>

Specified by:

replace in interface Seq<T>

Specified by:

replace in interface Traversable<T>

Parameters:

currentElement - the element to be replaced

newElement - the replacement element

Returns:

a new Traversable with the first occurrence of currentElement replaced by newElement

replaceAll

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

Description copied from interface: Traversable

Replaces all occurrences of 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 - the element to be replaced

newElement - the replacement element

Returns:

a new Traversable with all occurrences of currentElement replaced by newElement

retainAll

default List<T> retainAll(@NonNull Iterable<? extends T> elements)

Description copied from interface: Traversable

Retains only the elements from this Traversable that are contained in the given elements.

Specified by:

retainAll in interface LinearSeq<T>

Specified by:

retainAll in interface Seq<T>

Specified by:

retainAll in interface Traversable<T>

Parameters:

elements - the elements to keep

Returns:

a new Traversable containing only the elements present in elements, in their original order

reverse

default List<T> reverse()

Description copied from interface: Seq

Returns a new sequence with the order of elements reversed.

Specified by:

reverse in interface LinearSeq<T>

Specified by:

reverse in interface Seq<T>

Returns:

a new Seq with elements in reversed order

rotateLeft

default List<T> rotateLeft(int n)

Description copied from interface: Seq

Returns a new sequence with the elements circularly rotated to the left by the specified distance.

Example:

// Result: 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 - the number of positions to rotate left

Returns:

a new Seq with elements rotated left

rotateRight

default List<T> rotateRight(int n)

Description copied from interface: Seq

Returns a new sequence with the elements circularly rotated to the right by the specified distance.

Example:

// Result: 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 - the number of positions to rotate right

Returns:

a new Seq with elements rotated right

scan

default List<T> scan(T zero,
 @NonNull BiFunction<? super T, ? super T, ? extends T> operation)

Description copied from interface: Traversable

Computes a prefix scan of the elements of this Traversable.

The neutral element zero 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 - the neutral element for the operator

operation - an associative binary operator

Returns:

a new Traversable containing the prefix scan of the elements

scanLeft

default <U> List<U> scanLeft(U zero,
 @NonNull BiFunction<? super U, ? super T, ? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator from left to right.

Will not terminate for infinite collections. The results may vary across runs unless the collection 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 resulting elements

Parameters:

zero - the initial value

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

Returns:

a new Traversable containing the cumulative results

scanRight

default <U> List<U> scanRight(U zero,
 @NonNull BiFunction<? super T, ? super U, ? extends U> operation)

Description copied from interface: Traversable

Produces a collection containing cumulative results of applying the operator from right to left.

The head of the resulting collection is the last cumulative result. Will not terminate for infinite collections. Results may vary across runs unless the collection 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 resulting elements

Parameters:

zero - the initial value

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

Returns:

a new Traversable containing the cumulative results

shuffle

default List<T> shuffle()

Description copied from interface: Seq

Returns a new sequence with the elements randomly shuffled.

Specified by:

shuffle in interface LinearSeq<T>

Specified by:

shuffle in interface Seq<T>

Returns:

a new Seq containing the same elements in a random order

slice

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

Description copied from interface: Seq

Returns a subsequence (slice) of this sequence, starting at beginIndex (inclusive) and ending at endIndex (exclusive).

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 may throw an exception instead of returning a sequence in some cases.

Specified by:

slice in interface LinearSeq<T>

Specified by:

slice in interface Seq<T>

Parameters:

beginIndex - the starting index (inclusive)

endIndex - the ending index (exclusive)

Returns:

a new Seq representing the specified slice

slideBy

default Iterator<List<T>> slideBy(@NonNull Function<? super T, ?> classifier)

Description copied from interface: Traversable

Partitions this Traversable into consecutive non-overlapping windows according to a classification function.

Each window contains elements with the same class, as determined by classifier. Two consecutive elements belong to the same window only if classifier returns equal values for both. Otherwise, the current window ends and a new window begins with the next element.

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 classifying elements into groups

Returns:

An Iterator of windows (grouped elements)

sliding

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

Description copied from interface: Traversable

Slides a window of a given size over this Traversable with a step size of 1.

This is equivalent to calling Traversable.sliding(int, int) with a step size of 1.

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:

An Iterator of windows, each containing up to size elements

sliding

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

Description copied from interface: Traversable

Slides a window of a specific size with a given step 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:

an Iterator of windows with the given size and step

sorted

default List<T> sorted()

Description copied from interface: Seq

Returns a new sequence with elements sorted according to their natural order.

Specified by:

sorted in interface LinearSeq<T>

Specified by:

sorted in interface Seq<T>

Returns:

a new Seq with elements in natural order

sorted

default List<T> sorted(@NonNull Comparator<? super T> comparator)

Description copied from interface: Seq

Returns a new sequence with elements sorted according to the given Comparator.

Specified by:

sorted in interface LinearSeq<T>

Specified by:

sorted in interface Seq<T>

Parameters:

comparator - the comparator used to order elements; must not be null

Returns:

a new Seq with elements sorted according to the comparator

sortBy

default <U extends Comparable<? super U>> List<T> sortBy(@NonNull Function<? super T, ? extends U> mapper)

Description copied from interface: Seq

Returns a new sequence sorted by comparing elements in a different domain defined by the given mapper.

Specified by:

sortBy in interface LinearSeq<T>

Specified by:

sortBy in interface Seq<T>

Type Parameters:

U - the type used for comparison

Parameters:

mapper - a function mapping elements to a Comparable domain; must not be null

Returns:

a new Seq sorted according to the mapped values

sortBy

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

Description copied from interface: Seq

Returns a new sequence sorted by comparing elements in a different domain defined by the given mapper, using the provided comparator.

Specified by:

sortBy in interface LinearSeq<T>

Specified by:

sortBy in interface Seq<T>

Type Parameters:

U - the type used for comparison

Parameters:

comparator - the comparator used to compare mapped values; must not be null

mapper - a function mapping elements to the domain for comparison; must not be null

Returns:

a new Seq sorted according to the mapped values and comparator

span

default Tuple2<List<T>,List<T>> span(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Splits this Traversable into a prefix and remainder according to the given predicate.

The first element of the returned Tuple is the longest prefix of elements satisfying predicate, and the second element is the remaining elements.

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 used to determine the prefix

Returns:

a Tuple containing the prefix and remainder

splitAt

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

Description copied from interface: Seq

Splits this sequence 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 - the index at which to split

Returns:

a Tuple2 containing the first n elements and the remaining elements

splitAt

default Tuple2<List<T>,List<T>> splitAt(@NonNull Predicate<? super T> predicate)

Description copied from interface: Seq

Splits this sequence at the first element satisfying the given predicate.

Specified by:

splitAt in interface Seq<T>

Parameters:

predicate - the predicate used to determine the split point; must not be null

Returns:

a Tuple2 containing the sequence before the first matching element and the remaining sequence

splitAtInclusive

default Tuple2<List<T>,List<T>> splitAtInclusive(@NonNull Predicate<? super T> predicate)

Description copied from interface: Seq

Splits this sequence at the first element satisfying the given predicate, including the element in the first part.

Specified by:

splitAtInclusive in interface Seq<T>

Parameters:

predicate - the predicate used to determine the split point; must not be null

Returns:

a Tuple2 containing the sequence up to and including the first matching element and the remaining sequence

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 List<T> subSequence(int beginIndex)

Description copied from interface: Seq

Returns a Seq that is a subsequence of this sequence, starting from the specified beginIndex and extending to the end of this sequence.

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 provides similar functionality but does not throw an exception for out-of-bounds indices.

Specified by:

subSequence in interface LinearSeq<T>

Specified by:

subSequence in interface Seq<T>

Parameters:

beginIndex - the starting index (inclusive) of the subsequence

Returns:

a new Seq representing the subsequence from beginIndex to the end

subSequence

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

Description copied from interface: Seq

Returns a Seq that is a subsequence of this sequence, starting from the specified beginIndex (inclusive) and ending at endIndex (exclusive).

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 exceptions when indices are out of range.

Specified by:

subSequence in interface LinearSeq<T>

Specified by:

subSequence in interface Seq<T>

Parameters:

beginIndex - the starting index (inclusive) of the subsequence

endIndex - the ending index (exclusive) of the subsequence

Returns:

a new Seq representing the subsequence from beginIndex to endIndex - 1

tail

List<T> tail()

Description copied from interface: Traversable

Returns a new Traversable without its first element.

Specified by:

tail in interface LinearSeq<T>

Specified by:

tail in interface Seq<T>

Specified by:

tail in interface Traversable<T>

Returns:

a new Traversable containing all elements except the first

tailOption

default Option<List<T>> tailOption()

Description copied from interface: Traversable

Returns a new Traversable without its first element as 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) if non-empty, otherwise None

take

default List<T> take(int n)

Description copied from interface: Traversable

Returns the first n elements of this Traversable, or all elements if n exceeds the length.

Equivalent to sublist(0, max(0, min(length(), n))), but safe for n < 0 or n > length().

If n < 0, an empty instance is returned. If n > length(), the full instance 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 Traversable containing the first n elements

takeUntil

default List<T> takeUntil(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Takes elements from this Traversable until the given predicate holds for an element.

Equivalent to takeWhile(predicate.negate()), but useful when using method references that 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 sequentially on the elements

Returns:

a new Traversable containing all elements before the first one that satisfies the predicate

takeWhile

default List<T> takeWhile(@NonNull Predicate<? super T> predicate)

Description copied from interface: Traversable

Takes elements from this Traversable while the given predicate holds.

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 sequentially on the elements

Returns:

a new Traversable containing all elements up to (but not including) the first one that does not satisfy the predicate

takeRight

default List<T> takeRight(int n)

Description copied from interface: Traversable

Returns the last n elements of this Traversable, or all elements if n exceeds the length.

Equivalent to sublist(max(0, length() - n), length()), but safe for n < 0 or n > length().

If n < 0, an empty instance is returned. If n > length(), the full instance 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 from the end

Returns:

a new Traversable containing the last n elements

takeRightUntil

default List<T> takeRightUntil(@NonNull Predicate<? super T> predicate)

Description copied from interface: Seq

Takes elements from the end of the sequence until an element satisfies the given predicate. The returned sequence starts after the last element that satisfies the predicate.

Specified by:

takeRightUntil in interface LinearSeq<T>

Specified by:

takeRightUntil in interface Seq<T>

Parameters:

predicate - a condition to test elements, starting from the end

Returns:

a new sequence containing all elements after the last element that satisfies the predicate

takeRightWhile

default List<T> takeRightWhile(@NonNull Predicate<? super T> predicate)

Description copied from interface: Seq

Takes elements from the end of the sequence while the given predicate holds.

This is an equivalent to takeRightUntil(predicate.negate()). Useful when using method references that cannot be negated directly.

Specified by:

takeRightWhile in interface LinearSeq<T>

Specified by:

takeRightWhile in interface Seq<T>

Parameters:

predicate - a condition to test elements, starting from the end

Returns:

a new sequence containing all elements after the last element that does not satisfy the predicate

transform

default <U> U transform(@NonNull Function<? super List<T>, ? extends U> f)

Transforms this List.

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<List<T1>,List<T2>> unzip(@NonNull Function<? super T, Tuple2<? extends T1, ? extends T2>> unzipper)

Description copied from interface: Traversable

Unzips the elements of this Traversable by mapping each element to a pair and splitting them into two separate Traversable collections.

Specified by:

unzip in interface LinearSeq<T>

Specified by:

unzip in interface Seq<T>

Specified by:

unzip in interface Traversable<T>

Type Parameters:

T1 - type of the first element in the resulting pairs

T2 - type of the second element in the resulting pairs

Parameters:

unzipper - a function that maps elements of this Traversable to pairs

Returns:

a Tuple2 containing two Traversable collections with the split elements

unzip3

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

Description copied from interface: Traversable

Unzips the elements of this Traversable by mapping each element to a triple and splitting them into three separate Traversable collections.

Specified by:

unzip3 in interface Seq<T>

Specified by:

unzip3 in interface Traversable<T>

Type Parameters:

T1 - type of the first element in the resulting triples

T2 - type of the second element in the resulting triples

T3 - type of the third element in the resulting triples

Parameters:

unzipper - a function that maps elements of this Traversable to triples

Returns:

a Tuple3 containing three Traversable collections with the split elements

update

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

Description copied from interface: Seq

Returns a new Seq with the element at the specified index replaced by the given value.

Specified by:

update in interface LinearSeq<T>

Specified by:

update in interface Seq<T>

Parameters:

index - the index of the element to update

element - the new element to set at the specified index

Returns:

a new Seq with the updated element

update

default List<T> update(int index,
 @NonNull Function<? super T, ? extends T> updater)

Description copied from interface: Seq

Returns a new Seq with the element at the specified index updated using the given function.

Specified by:

update in interface LinearSeq<T>

Specified by:

update in interface Seq<T>

Parameters:

index - the index of the element to update

updater - a function that computes the new element from the existing element

Returns:

a new Seq with the element at index transformed by updater

zip

default <U> List<Tuple2<T,U>> zip(@NonNull Iterable<? extends U> that)

Description copied from interface: Traversable

Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable. Pairing stops when either collection runs out of elements; any remaining elements in the longer collection are ignored.

The length of the resulting Traversable is the minimum of the lengths of this Traversable and that.

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 elements in the second half of each pair

Parameters:

that - an Iterable providing the second element of each pair

Returns:

a new Traversable containing pairs of corresponding elements

zipWith

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

Description copied from interface: Traversable

Returns a Traversable by combining elements of this Traversable with elements of another Iterable using a mapping function. Pairing stops when either collection runs out of elements.

The length of the resulting Traversable is the minimum of the lengths of this Traversable and that.

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 elements in the second parameter of the mapper

R - the type of elements in the resulting Traversable

Parameters:

that - an Iterable providing the second parameter of the mapper

mapper - a function that combines elements from this and that into a new element

Returns:

a new Traversable containing mapped elements

zipAll

default <U> List<Tuple2<T,U>> zipAll(@NonNull Iterable<? extends U> that,
 T thisElem,
 U thatElem)

Description copied from interface: Traversable

Returns a Traversable formed by pairing elements of this Traversable with elements of another Iterable, filling in placeholder elements when one collection is shorter than the other.

The length of the resulting Traversable is the maximum of the lengths of this Traversable and that.

If this Traversable is shorter than that, thisElem is used as a filler. Conversely, if that is shorter, thatElem is used.

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 elements in the second half of each pair

Parameters:

that - an Iterable providing the second element of each pair

thisElem - the element used to fill missing values if this Traversable is shorter than that

thatElem - the element used to fill missing values if that is shorter than this Traversable

Returns:

a new Traversable containing pairs of elements, including fillers as needed

zipWithIndex

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

Description copied from interface: Traversable

Zips this Traversable with its indices, starting at 0.

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 each element paired with its index

zipWithIndex

default <U> List<U> zipWithIndex(@NonNull BiFunction<? super T, ? super Integer, ? extends U> mapper)

Description copied from interface: Traversable

Zips this Traversable with its indices and maps the resulting pairs using the provided mapper.

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 elements in the resulting Traversable

Parameters:

mapper - a function mapping an element and its index to a new element

Returns:

a new Traversable containing the mapped elements