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
Type members
Classlikes
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.
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.
- Source:
- Iterator.scala
Value members
Abstract methods
Check if there is a next element available.
Check if there is a next element available.
- Returns:
trueif there is a next element,falseotherwise- Note:
Reuse: The iterator remains valid for further use whatever result is returned.
- Source:
- Iterator.scala
Return the next element and advance the iterator.
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
Creates a buffered iterator from this iterator.
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
Tests whether this iterator contains a given value as an element.
Tests whether this iterator contains a given value as an element.
Note: may not terminate for infinite iterators.
- Value parameters:
- elem
the element to test.
- Returns:
trueif this iterator produces some value that is is equal (as determined by==) toelem,falseotherwise.- 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.
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
Builds a new iterator from this one without any duplicated elements as determined by == after applying
the transforming function f.
Builds a new iterator from this one without any duplicated elements as determined by == after applying
the transforming function f.
- Type parameters:
- B
the type of the elements after being transformed by
f
- Value parameters:
- 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
Creates two new iterators that both iterate over the same elements as this iterator (in the same order).
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
Returns an iterator which groups this iterator into fixed size blocks.
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
Returns the index of the first occurrence of the specified object in this iterable object.
Returns the index of the first occurrence of the specified object in this iterable object.
Note: may not terminate for infinite iterators.
- Value parameters:
- elem
element to search for.
- Returns:
the index of the first occurrence of
elemin 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
Returns the index of the first occurrence of the specified object in this iterable object after or at some start index.
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 parameters:
- elem
element to search for.
- from
the start index
- Returns:
the index
>= fromof the first occurrence ofelemin 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
- Definition Classes
- Source:
- Iterator.scala
Wraps the value of next() in an option.
Wraps the value of next() in an option.
- Returns:
Some(next)if a next element exists,Noneotherwise.- Source:
- Iterator.scala
A copy of this iterator with an element value appended until a given target length is reached.
A copy of this iterator with an element value appended until a given target length is reached.
- Type parameters:
- B
the element type of the returned iterator.
- Value parameters:
- 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
elemso that the resulting collection has a length of at leastlen.- Source:
- Iterator.scala
Partitions this iterator in two iterators according to a predicate.
Partitions this iterator in two iterators according to a predicate.
- Value parameters:
- p
the predicate on which to partition
- Returns:
a pair of iterators: the iterator that satisfies the predicate
pand 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
Returns this iterator with patched values.
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 parameters:
- 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
Checks whether corresponding elements of the given iterable collection
compare equal (with respect to ==) to elements of this iterator.
Checks whether corresponding elements of the given iterable collection
compare equal (with respect to ==) to elements of this iterator.
- Type parameters:
- B
the type of the elements of collection
that.
- Value parameters:
- that
the collection to compare
- Returns:
trueif both collections contain equal elements in the same order,falseotherwise.- Source:
- Iterator.scala
Returns an iterator which presents a "sliding window" view of this iterator.
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 parameters:
- size
the number of elements per group
- step
the distance between the first elements of successive groups
- Returns:
A
GroupedIteratorproducingSeq[B]s of sizesize, except the last element (which may be the only element) will be truncated if there are fewer thansizeelements 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
Splits this iterator into a prefix/suffix pair according to a predicate.
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
Converts this iterator to a string.
Converts this iterator to a string.
- Returns:
"" - Note:
Reuse: The iterator remains valid for further use whatever result is returned.
- Definition Classes
- Source:
- Iterator.scala
Creates an iterator over all the elements of this iterator that
satisfy the predicate p.
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 parameters:
- 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
Deprecated methods
- Deprecated
- Definition Classes
- Source:
- Iterator.scala
- Deprecated
- Source:
- Iterator.scala
Inherited methods
Appends all elements of this collection to a string builder.
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 parameters:
- b
the string builder to which elements are appended.
- Returns:
the string builder
bto which elements were appended.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Appends all elements of this collection to a string builder using a separator string.
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 parameters:
- b
the string builder to which elements are appended.
- sep
the separator string.
- Returns:
the string builder
bto 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.
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 parameters:
- 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
bto which elements were appended.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
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 parameters:
- pf
the partial function
- Returns:
an option value containing pf applied to the first value for which it is defined, or
Noneif none exists.- Example:
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Copy elements to an array, returning the number of elements written.
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 parameters:
- B
the type of the elements of the array.
- Value parameters:
- 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
Copy elements to an array, returning the number of elements written.
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 parameters:
- B
the type of the elements of the array.
- Value parameters:
- 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
Copy elements to an array, returning the number of elements written.
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 parameters:
- B
the type of the elements of the array.
- Value parameters:
- 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
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
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 parameters:
- B
the type of the elements of
that
- Value parameters:
- p
the test predicate, which relates elements from both collections
- that
the other collection
- Returns:
trueif both collections have the same length andp(x, y)istruefor all corresponding elementsxof this iterator andyofthat, otherwisefalse- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Counts the number of elements in the collection which satisfy a predicate.
Counts the number of elements in the collection which satisfy a predicate.
Note: will not terminate for infinite-sized collections.
- Value parameters:
- p
the predicate used to test elements.
- Returns:
the number of elements satisfying the predicate
p.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Tests whether a predicate holds for at least one element of this collection.
Tests whether a predicate holds for at least one element of this collection.
Note: may not terminate for infinite-sized collections.
- Value parameters:
- p
the predicate used to test elements.
- Returns:
trueif the given predicatepis satisfied by at least one element of this collection, otherwisefalse- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Finds the first element of the collection satisfying a predicate, if any.
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 parameters:
- p
the predicate used to test elements.
- Returns:
an option value containing the first element in the collection that satisfies
p, orNoneif none exists.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Folds the elements of this collection using the specified associative binary operator.
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 parameters:
- A1
a type parameter for the binary operator, a supertype of
A.
- Value parameters:
- 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.,
Nilfor list concatenation, 0 for addition, or 1 for multiplication).
- Returns:
the result of applying the fold operator
opbetween all the elements andz, orzif this collection is empty.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Applies a binary operator to a start value and all elements of this collection, going left to right.
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 parameters:
- B
the result type of the binary operator.
- Value parameters:
- op
the binary operator.
- z
the start value.
- Returns:
the result of inserting
opbetween consecutive elements of this collection, going left to right with the start valuezon the left:op(...op(z, x1), x2, ..., xn)wherex1, ..., xnare the elements of this collection. Returnszif this collection is empty.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Applies a binary operator to all elements of this collection and a start value, going right to left.
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 parameters:
- B
the result type of the binary operator.
- Value parameters:
- op
the binary operator.
- z
the start value.
- Returns:
the result of inserting
opbetween consecutive elements of this collection, going right to left with the start valuezon the right:op(x1, op(x2, ... op(xn, z)...))wherex1, ..., xnare the elements of this collection. Returnszif this collection is empty.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Tests whether a predicate holds for all elements of this collection.
Tests whether a predicate holds for all elements of this collection.
Note: may not terminate for infinite-sized collections.
- Value parameters:
- p
the predicate used to test elements.
- Returns:
trueif this collection is empty or the given predicatepholds for all elements of this collection, otherwisefalse.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Apply f to each element for its side effects
Note: [U] parameter needed to help scalac's type inference.
Apply f to each element for its side effects
Note: [U] parameter needed to help scalac's type inference.
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Tests whether this collection can be repeatedly traversed.
Tests whether this collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
- Returns:
trueif it is repeatedly traversable,falseotherwise.- 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
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The type over which the ordering is defined.
- Value parameters:
- 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
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The result type of the function f.
- Value parameters:
- 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
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The result type of the function f.
- Value parameters:
- 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
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The type over which the ordering is defined.
- Value parameters:
- 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
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The type over which the ordering is defined.
- Value parameters:
- 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
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The result type of the function f.
- Value parameters:
- 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
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The result type of the function f.
- Value parameters:
- 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
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
The type over which the ordering is defined.
- Value parameters:
- 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
Displays all elements of this collection in a 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
Displays all elements of this collection in a string using a separator string.
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
- Value parameters:
- 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 stringsep.- Example:
List(1, 2, 3).mkString("|") = "1|2|3"- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Displays all elements of this collection in a string using start, end, and separator strings.
Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
- Value parameters:
- 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
startand ends with the stringend. Inside, the string representations (w.r.t. the methodtoString) of all elements of this collection are separated by the stringsep.- Example:
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Tests whether the collection is not empty.
Tests whether the collection is not empty.
- Returns:
trueif the collection contains at least one element,falseotherwise.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
the result type of the
*operator.
- Value parameters:
- 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 innum.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Reduces the elements of this collection using the specified associative binary operator.
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 parameters:
- B
A type parameter for the binary operator, a supertype of
A.
- Value parameters:
- op
A binary operator that must be associative.
- Returns:
The result of applying reduce operator
opbetween all the elements if the collection is nonempty.- Throws:
- UnsupportedOperationException
if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Applies a binary operator to all elements of this collection, going left to right.
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 parameters:
- B
the result type of the binary operator.
- Value parameters:
- op
the binary operator.
- Returns:
the result of inserting
opbetween consecutive elements of this collection, going left to right:op( op( ... op(x1, x2) ..., xn-1), xn)wherex1, ..., xnare the elements of this collection.- Throws:
- UnsupportedOperationException
if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Optionally applies a binary operator to all elements of this collection, going left to right.
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 parameters:
- B
the result type of the binary operator.
- Value parameters:
- op
the binary operator.
- Returns:
an option value containing the result of
reduceLeft(op)if this collection is nonempty,Noneotherwise.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Reduces the elements of this collection, if any, using the specified associative binary operator.
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 parameters:
- B
A type parameter for the binary operator, a supertype of
A.
- Value parameters:
- op
A binary operator that must be associative.
- Returns:
An option value containing result of applying reduce operator
opbetween all the elements if the collection is nonempty, andNoneotherwise.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Applies a binary operator to all elements of this collection, going right to left.
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 parameters:
- B
the result type of the binary operator.
- Value parameters:
- op
the binary operator.
- Returns:
the result of inserting
opbetween consecutive elements of this collection, going right to left:op(x1, op(x2, ..., op(xn-1, xn)...))wherex1, ..., xnare the elements of this collection.- Throws:
- UnsupportedOperationException
if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Optionally applies a binary operator to all elements of this collection, going right to left.
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 parameters:
- B
the result type of the binary operator.
- Value parameters:
- op
the binary operator.
- Returns:
an option value containing the result of
reduceRight(op)if this collection is nonempty,Noneotherwise.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
The size of this collection.
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
Splits this collection into a prefix/suffix pair at a given position.
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 parameters:
- n
the position at which to split.
- Returns:
a pair of collections consisting of the first
nelements of this collection, and the other elements.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Returns a scala.collection.Stepper for the elements of this collection.
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.
For collections of
Int,Short,ByteorChar, an scala.collection.IntStepper is returnedFor collections of
DoubleorFloat, a scala.collection.DoubleStepper is returnedFor collections of
Longa scala.collection.LongStepper is returnedFor any other element type, an scala.collection.AnyStepper is returned
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
Sums up the elements of this collection.
Sums up the elements of this collection.
Note: will not terminate for infinite-sized collections.
- Type parameters:
- B
the result type of the
+operator.
- Value parameters:
- 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 innum.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Given a collection factory factory, convert this collection to the appropriate
representation for the current element type A.
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]
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Convert collection to array.
Convert collection to array.
Implementation note: DO NOT call Array.from from this method.
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
- Returns:
This collection as a
Seq[A]. This is equivalent toto(Seq)but might be faster.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
Deprecated and Inherited methods
- Deprecated
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
- Deprecated
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
- Deprecated
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
- Deprecated
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
- Deprecated
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala
- Deprecated
- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala