Iterator

trait Iterator[+A] extends IterableOnce[A] with IterableOnceOps[A, [A] =>> Iterator[A], Iterator[A]]

Iterators are data structures that allow to iterate over a sequence of elements. They have a hasNext method for checking if there is a next element available, and a next method which returns the next element and advances the iterator.

An iterator is mutable: most operations on it change its state. While it is often used to iterate through the elements of a collection, it can also be used without being backed by any collection (see constructors on the companion object).

It is of particular importance to note that, unless stated otherwise, one should never use an iterator after calling a method on it. The two most important exceptions are also the sole abstract methods: next and hasNext.

Both these methods can be called any number of times without having to discard the iterator. Note that even hasNext may cause mutation -- such as when iterating from an input stream, where it will block until the stream is closed or some input becomes available.

Consider this example for safe and unsafe use:

def f[A](it: Iterator[A]) = { if (it.hasNext) { // Safe to reuse "it" after "hasNext" it.next() // Safe to reuse "it" after "next" val remainder = it.drop(2) // it is *not* safe to use "it" again after this line! remainder.take(2) // it is *not* safe to use "remainder" after this line! } else it }
Companion
object
Source
Iterator.scala
trait IterableOnceOps[A, [A] =>> Iterator[A], Iterator[A]]
trait IterableOnce[A]
class Object
trait Matchable
class Any

Type members

Classlikes

class GroupedIterator[B >: A](self: Iterator[B], size: Int, step: Int) extends AbstractIterator[Seq[B]]

A flexible iterator for transforming an Iterator[A] into an Iterator[Seq[A]], with configurable sequence size, step, and strategy for dealing with elements which don't fit evenly.

Typical uses can be achieved via methods grouped and sliding.

Value members

Abstract methods

Check if there is a next element available.

Returns

true if there is a next element, false otherwise

Note

Reuse: The iterator remains valid for further use whatever result is returned.

Source
Iterator.scala
@throws(scala.throws.$lessinit$greater$default$1[scala.NoSuchElementException])
def next(): A

Return the next element and advance the iterator.

Returns

the next element.

Throws
NoSuchElementException

if there is no next element.

Note

Reuse: Advances the iterator, which may exhaust the elements. It is valid to make additional calls on the iterator.

Source
Iterator.scala

Concrete methods

final def ++[B >: A](xs: => IterableOnce[B]): Iterator[B]

Creates a buffered iterator from this iterator.

Returns

a buffered iterator producing the same values as this iterator.

See also
Note

Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.

Source
Iterator.scala
def collect[B](pf: PartialFunction[A, B]): Iterator[B]
def concat[B >: A](xs: => IterableOnce[B]): Iterator[B]
def contains(elem: Any): Boolean

Tests whether this iterator contains a given value as an element.

Note: may not terminate for infinite iterators.

Value Params
elem

the element to test.

Returns

true if this iterator produces some value that is is equal (as determined by ==) to elem, false otherwise.

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Source
Iterator.scala

Builds a new iterator from this one without any duplicated elements on it.

Returns

iterator with distinct elements

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Source
Iterator.scala
def distinctBy[B](f: A => B): Iterator[A]

Builds a new iterator from this one without any duplicated elements as determined by == after applying the transforming function f.

Type Params
B

the type of the elements after being transformed by f

Value Params
f

The transforming function whose result is used to determine the uniqueness of each element

Returns

iterator with distinct elements

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Source
Iterator.scala
def drop(n: Int): Iterator[A]
def dropWhile(p: A => Boolean): Iterator[A]
def duplicate: (Iterator[A], Iterator[A])

Creates two new iterators that both iterate over the same elements as this iterator (in the same order). The duplicate iterators are considered equal if they are positioned at the same element.

Given that most methods on iterators will make the original iterator unfit for further use, this methods provides a reliable way of calling multiple such methods on an iterator.

Returns

a pair of iterators

Note

The implementation may allocate temporary storage for elements iterated by one iterator but not yet by the other.

Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.

Source
Iterator.scala
def filter(p: A => Boolean): Iterator[A]
def filterNot(p: A => Boolean): Iterator[A]
def flatMap[B](f: A => IterableOnce[B]): Iterator[B]
def flatten[B](ev: A => IterableOnce[B]): Iterator[B]
def grouped[B >: A](size: Int): GroupedIterator[B]

Returns an iterator which groups this iterator into fixed size blocks. Example usages:

// Returns List(List(1, 2, 3), List(4, 5, 6), List(7))) (1 to 7).iterator.grouped(3).toList // Returns List(List(1, 2, 3), List(4, 5, 6)) (1 to 7).iterator.grouped(3).withPartial(false).toList // Returns List(List(1, 2, 3), List(4, 5, 6), List(7, 20, 25) // Illustrating that withPadding's argument is by-name. val it2 = Iterator.iterate(20)(_ + 5) (1 to 7).iterator.grouped(3).withPadding(it2.next).toList
Note

Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.

Source
Iterator.scala
def indexOf[B >: A](elem: B): Int

Returns the index of the first occurrence of the specified object in this iterable object.

Note: may not terminate for infinite iterators.

Value Params
elem

element to search for.

Returns

the index of the first occurrence of elem in the values produced by this iterator, or -1 if such an element does not exist until the end of the iterator is reached.

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Source
Iterator.scala
def indexOf[B >: A](elem: B, from: Int): Int

Returns the index of the first occurrence of the specified object in this iterable object after or at some start index.

Note: may not terminate for infinite iterators.

Value Params
elem

element to search for.

from

the start index

Returns

the index >= from of the first occurrence of elem in the values produced by this iterator, or -1 if such an element does not exist until the end of the iterator is reached.

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Source
Iterator.scala
def indexWhere(p: A => Boolean, from: Int): Int
@deprecatedOverriding("isEmpty is defined as !hasNext; override hasNext instead", "2.13.0")
override def isEmpty: Boolean
Definition Classes
Source
Iterator.scala
final def length: Int
def map[B](f: A => B): Iterator[B]
def nextOption(): Option[A]

Wraps the value of next() in an option.

Returns

Some(next) if a next element exists, None otherwise.

Source
Iterator.scala
def padTo[B >: A](len: Int, elem: B): Iterator[B]

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

Type Params
B

the element type of the returned iterator.

Value Params
elem

the padding value

len

the target length

Returns

a new iterator consisting of all elements of this iterator followed by the minimal number of occurrences of elem so that the resulting collection has a length of at least len.

Source
Iterator.scala
def partition(p: A => Boolean): (Iterator[A], Iterator[A])

Partitions this iterator in two iterators according to a predicate.

Value Params
p

the predicate on which to partition

Returns

a pair of iterators: the iterator that satisfies the predicate p and the iterator that does not. The relative order of the elements in the resulting iterators is the same as in the original iterator.

Note

Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.

Source
Iterator.scala
def patch[B >: A](from: Int, patchElems: Iterator[B], replaced: Int): Iterator[B]

Returns this iterator with patched values. Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original iterator appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.

Value Params
from

The start index from which to patch

patchElems

The iterator of patch values

replaced

The number of values in the original iterator that are replaced by the patch.

Note

Reuse: After calling this method, one should discard the iterator it was called on, as well as the one passed as a parameter, and use only the iterator that was returned. Using the old iterators is undefined, subject to change, and may result in changes to the new iterator as well.

Source
Iterator.scala
def sameElements[B >: A](that: IterableOnce[B]): Boolean

Checks whether corresponding elements of the given iterable collection compare equal (with respect to ==) to elements of this iterator.

Type Params
B

the type of the elements of collection that.

Value Params
that

the collection to compare

Returns

true if both collections contain equal elements in the same order, false otherwise.

Source
Iterator.scala
def scanLeft[B](z: B)(op: (B, A) => B): Iterator[B]
def slice(from: Int, until: Int): Iterator[A]
def sliding[B >: A](size: Int, step: Int): GroupedIterator[B]

Returns an iterator which presents a "sliding window" view of this iterator. The first argument is the window size, and the second argument step is how far to advance the window on each iteration. The step defaults to 1.

The returned GroupedIterator can be configured to either pad a partial result to size size or suppress the partial result entirely.

Example usages:

// Returns List(ArraySeq(1, 2, 3), ArraySeq(2, 3, 4), ArraySeq(3, 4, 5)) (1 to 5).iterator.sliding(3).toList // Returns List(ArraySeq(1, 2, 3, 4), ArraySeq(4, 5)) (1 to 5).iterator.sliding(4, 3).toList // Returns List(ArraySeq(1, 2, 3, 4)) (1 to 5).iterator.sliding(4, 3).withPartial(false).toList // Returns List(ArraySeq(1, 2, 3, 4), ArraySeq(4, 5, 20, 25)) // Illustrating that withPadding's argument is by-name. val it2 = Iterator.iterate(20)(_ + 5) (1 to 5).iterator.sliding(4, 3).withPadding(it2.next).toList
Value Params
size

the number of elements per group

step

the distance between the first elements of successive groups

Returns

A GroupedIterator producing Seq[B]s of size size, except the last element (which may be the only element) will be truncated if there are fewer than size elements remaining to be grouped. This behavior can be configured.

Note

Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.

Source
Iterator.scala
def span(p: A => Boolean): (Iterator[A], Iterator[A])

Splits this iterator into a prefix/suffix pair according to a predicate.

Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p), provided the evaluation of the predicate p does not cause any side-effects.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Note

Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.

Source
Iterator.scala
def take(n: Int): Iterator[A]
def takeWhile(p: A => Boolean): Iterator[A]
override def tapEach[U](f: A => U): Iterator[A]
Definition Classes
Source
Iterator.scala
override def toString: String

Converts this iterator to a string.

Returns

""

Note

Reuse: The iterator remains valid for further use whatever result is returned.

Definition Classes
Any
Source
Iterator.scala
def withFilter(p: A => Boolean): Iterator[A]

Creates an iterator over all the elements of this iterator that satisfy the predicate p. The order of the elements is preserved.

Note: withFilter is the same as filter on iterators. It exists so that for-expressions with filters work over iterators.

Value Params
p

the predicate used to test values.

Returns

an iterator which produces those values of this iterator which satisfy the predicate p.

Note

Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.

Source
Iterator.scala
def zip[B](that: IterableOnce[B]): Iterator[(A, B)]
def zipAll[A1 >: A, B](that: IterableOnce[B], thisElem: A1, thatElem: B): Iterator[(A1, B)]

Deprecated methods

@deprecated("hasDefiniteSize on Iterator is the same as isEmpty", "2.13.0") @inline
final override def hasDefiniteSize: Boolean
Deprecated
Definition Classes
Source
Iterator.scala
@deprecated("Call scanRight on an Iterable instead.", "2.13.0")
def scanRight[B](z: B)(op: (A, B) => B): Iterator[B]
Deprecated
Source
Iterator.scala
@deprecated("Iterator.seq always returns the iterator itself", "2.13.0")
def seq: Iterator[A]
Deprecated
Source
Iterator.scala

Inherited methods

Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.

Example:

scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> val h = a.addString(b) h: StringBuilder = 1234
Value Params
b

the string builder to which elements are appended.

Returns

the string builder b to which elements were appended.

Inherited from
IterableOnceOps
Source
IterableOnce.scala

Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection, separated by the string sep.

Example:

scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b, ", ") res0: StringBuilder = 1, 2, 3, 4
Value Params
b

the string builder to which elements are appended.

sep

the separator string.

Returns

the string builder b to which elements were appended.

Inherited from
IterableOnceOps
Source
IterableOnce.scala

Appends all elements of this collection to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example:

scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b , "List(" , ", " , ")") res5: StringBuilder = List(1, 2, 3, 4)
Value Params
b

the string builder to which elements are appended.

end

the ending string.

sep

the separator string.

start

the starting string.

Returns

the string builder b to which elements were appended.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def collectFirst[B](pf: PartialFunction[A, B]): Option[B]

Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params
pf

the partial function

Returns

an option value containing pf applied to the first value for which it is defined, or None if none exists.

Example

Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Int

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with at most len elements of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.

Type Params
B

the type of the elements of the array.

Value Params
len

the maximal number of elements to copy.

start

the starting index of xs.

xs

the array to fill.

Returns

the number of elements written to the array

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
def copyToArray[B >: A](xs: Array[B], start: Int): Int

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type Params
B

the type of the elements of the array.

Value Params
start

the starting index of xs.

xs

the array to fill.

Returns

the number of elements written to the array

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
def copyToArray[B >: A](xs: Array[B]): Int

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type Params
B

the type of the elements of the array.

Value Params
xs

the array to fill.

Returns

the number of elements written to the array

Note

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def corresponds[B](that: IterableOnce[B])(p: (A, B) => Boolean): Boolean

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Note: will not terminate for infinite-sized collections.

Type Params
B

the type of the elements of that

Value Params
p

the test predicate, which relates elements from both collections

that

the other collection

Returns

true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def count(p: A => Boolean): Int

Counts the number of elements in the collection which satisfy a predicate.

Note: will not terminate for infinite-sized collections.

Value Params
p

the predicate used to test elements.

Returns

the number of elements satisfying the predicate p.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def exists(p: A => Boolean): Boolean

Tests whether a predicate holds for at least one element of this collection.

Note: may not terminate for infinite-sized collections.

Value Params
p

the predicate used to test elements.

Returns

true if the given predicate p is satisfied by at least one element of this collection, otherwise false

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def find(p: A => Boolean): Option[A]

Finds the first element of the collection satisfying a predicate, if any.

Note: may not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params
p

the predicate used to test elements.

Returns

an option value containing the first element in the collection that satisfies p, or None if none exists.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1

Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Note: will not terminate for infinite-sized collections.

Type Params
A1

a type parameter for the binary operator, a supertype of A.

Value Params
op

a binary operator that must be associative.

z

a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., Nil for list concatenation, 0 for addition, or 1 for multiplication).

Returns

the result of applying the fold operator op between all the elements and z, or z if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def foldLeft[B](z: B)(op: (B, A) => B): B

Applies a binary operator to a start value and all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params
B

the result type of the binary operator.

Value Params
op

the binary operator.

z

the start value.

Returns

the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left: op(...op(z, x1), x2, ..., xn) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def foldRight[B](z: B)(op: (A, B) => B): B

Applies a binary operator to all elements of this collection and a start value, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params
B

the result type of the binary operator.

Value Params
op

the binary operator.

z

the start value.

Returns

the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right: op(x1, op(x2, ... op(xn, z)...)) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def forall(p: A => Boolean): Boolean

Tests whether a predicate holds for all elements of this collection.

Note: may not terminate for infinite-sized collections.

Value Params
p

the predicate used to test elements.

Returns

true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def foreach[U](f: A => U): Unit

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Tests whether this collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.

Returns

true if it is repeatedly traversable, false otherwise.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
Returns

The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

Inherited from
IterableOnce
Source
IterableOnce.scala
def max[B >: A](ord: Ordering[B]): A

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type Params
B

The type over which the ordering is defined.

Value Params
ord

An ordering to be used for comparing elements.

Returns

the largest element of this collection with respect to the ordering ord.

Throws
UnsupportedOperationException

if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def maxBy[B](f: A => B)(cmp: Ordering[B]): A

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params
B

The result type of the function f.

Value Params
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns

the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Throws
UnsupportedOperationException

if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def maxByOption[B](f: A => B)(cmp: Ordering[B]): Option[A]

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params
B

The result type of the function f.

Value Params
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns

an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def maxOption[B >: A](ord: Ordering[B]): Option[A]

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type Params
B

The type over which the ordering is defined.

Value Params
ord

An ordering to be used for comparing elements.

Returns

an option value containing the largest element of this collection with respect to the ordering ord.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def min[B >: A](ord: Ordering[B]): A

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type Params
B

The type over which the ordering is defined.

Value Params
ord

An ordering to be used for comparing elements.

Returns

the smallest element of this collection with respect to the ordering ord.

Throws
UnsupportedOperationException

if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def minBy[B](f: A => B)(cmp: Ordering[B]): A

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params
B

The result type of the function f.

Value Params
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns

the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Throws
UnsupportedOperationException

if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def minByOption[B](f: A => B)(cmp: Ordering[B]): Option[A]

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Type Params
B

The result type of the function f.

Value Params
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns

an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def minOption[B >: A](ord: Ordering[B]): Option[A]

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type Params
B

The type over which the ordering is defined.

Value Params
ord

An ordering to be used for comparing elements.

Returns

an option value containing the smallest element of this collection with respect to the ordering ord.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
final def mkString: String

Displays all elements of this collection in a string.

Delegates to addString, which can be overridden.

Returns

a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
final def mkString(sep: String): String

Displays all elements of this collection in a string using a separator string.

Delegates to addString, which can be overridden.

Value Params
sep

the separator string.

Returns

a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example

List(1, 2, 3).mkString("|") = "1|2|3"

Inherited from
IterableOnceOps
Source
IterableOnce.scala
final def mkString(start: String, sep: String, end: String): String

Displays all elements of this collection in a string using start, end, and separator strings.

Delegates to addString, which can be overridden.

Value Params
end

the ending string.

sep

the separator string.

start

the starting string.

Returns

a string representation of this collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example

List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"

Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0")

Tests whether the collection is not empty.

Returns

true if the collection contains at least one element, false otherwise.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def product[B >: A](num: Numeric[B]): B

Multiplies up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type Params
B

the result type of the * operator.

Value Params
num

an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.

Returns

the product of all elements of this collection with respect to the * operator in num.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def reduce[B >: A](op: (B, B) => B): B

Reduces the elements of this collection using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type Params
B

A type parameter for the binary operator, a supertype of A.

Value Params
op

A binary operator that must be associative.

Returns

The result of applying reduce operator op between all the elements if the collection is nonempty.

Throws
UnsupportedOperationException

if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def reduceLeft[B >: A](op: (B, A) => B): B

Applies a binary operator to all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params
B

the result type of the binary operator.

Value Params
op

the binary operator.

Returns

the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.

Throws
UnsupportedOperationException

if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def reduceLeftOption[B >: A](op: (B, A) => B): Option[B]

Optionally applies a binary operator to all elements of this collection, going left to right.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params
B

the result type of the binary operator.

Value Params
op

the binary operator.

Returns

an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def reduceOption[B >: A](op: (B, B) => B): Option[B]

Reduces the elements of this collection, if any, using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type Params
B

A type parameter for the binary operator, a supertype of A.

Value Params
op

A binary operator that must be associative.

Returns

An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def reduceRight[B >: A](op: (A, B) => B): B

Applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params
B

the result type of the binary operator.

Value Params
op

the binary operator.

Returns

the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.

Throws
UnsupportedOperationException

if this collection is empty.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def reduceRightOption[B >: A](op: (A, B) => B): Option[B]

Optionally applies a binary operator to all elements of this collection, going right to left.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Type Params
B

the result type of the binary operator.

Value Params
op

the binary operator.

Returns

an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
protected def reversed: Iterable[A]
def size: Int

The size of this collection.

Note: will not terminate for infinite-sized collections.

Returns

the number of elements in this collection.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def splitAt(n: Int): (Iterator[A], Iterator[A])

Splits this collection into a prefix/suffix pair at a given position.

Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value Params
n

the position at which to split.

Returns

a pair of collections consisting of the first n elements of this collection, and the other elements.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def stepper[S <: Stepper[_]](shape: StepperShape[A, S]): S

Returns a scala.collection.Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

Inherited from
IterableOnce
Source
IterableOnce.scala
def sum[B >: A](num: Numeric[B]): B

Sums up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type Params
B

the result type of the + operator.

Value Params
num

an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.

Returns

the sum of all elements of this collection with respect to the + operator in num.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def to[C1](factory: Factory[A, C1]): C1

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:

xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]

def toArray[B >: A](`evidence$1`: ClassTag[B]): Array[B]

Convert collection to array.

Implementation note: DO NOT call Array.from from this method.

final def toBuffer[B >: A]: Buffer[B]
def toList: List[A]
def toMap[K, V](ev: A <:< (K, V)): Map[K, V]
def toSeq: Seq[A]
Returns

This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.

Inherited from
IterableOnceOps
Source
IterableOnce.scala
def toSet[B >: A]: Set[B]

Deprecated and Inherited methods

@deprecated("Use foldLeft instead of /:", "2.13.0") @inline
final def /:[B](z: B)(op: (B, A) => B): B
Deprecated
Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecated("Use foldRight instead of :\\", "2.13.0") @inline
final def :\[B](z: B)(op: (A, B) => B): B
Deprecated
Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecated("`aggregate` is not relevant for sequential collections. Use `foldLeft(z)(seqop)` instead.", "2.13.0")
def aggregate[B](z: => B)(seqop: (B, A) => B, combop: (B, B) => B): B
Deprecated
Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecated("Use `dest ++= coll` instead", "2.13.0") @inline
final def copyToBuffer[B >: A](dest: Buffer[B]): Unit
Deprecated
Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecated("Use .iterator instead of .toIterator", "2.13.0") @inline
final def toIterator: Iterator[A]
Deprecated
Inherited from
IterableOnceOps
Source
IterableOnce.scala
@deprecated("Use .to(LazyList) instead of .toStream", "2.13.0") @inline
final def toStream: Stream[A]
Deprecated
Inherited from
IterableOnceOps
Source
IterableOnce.scala