Option
@SerialVersionUID(-114498752079829388L) sealed abstract class Option[+A] extends IterableOnce[A] with Product with Serializable
The most idiomatic way to use an Option instance is to treat it
as a collection or monad and use
map
,flatMap
, filter
, or
foreach
:val name: Option[String] = request getParameter "name"
val upper = name map { _.trim } filter { _.length != 0 } map { _.toUpperCase }
println(upper getOrElse "")
Note that this is equivalent to
val upper = for {
name <- request getParameter "name"
trimmed <- Some(name.trim)
upper <- Some(trimmed.toUpperCase) if trimmed.length != 0
} yield upper
println(upper getOrElse "")
Because of how for comprehension works, if
None
is returned
from request.getParameter
, the entire expression results in
None
This allows for sophisticated chaining of Option values without
having to check for the existence of a value.
These are useful methods that exist for both Some and
None
.
- isDefined — True if not empty
- isEmpty — True if empty
- nonEmpty — True if not empty
- orElse — Evaluate and return alternate optional value if empty
- getOrElse — Evaluate and return alternate value if empty
- get — Return value, throw exception if empty
- fold — Apply function on optional value, return default if empty
- map — Apply a function on the optional value
- flatMap — Same as map but function must return an optional value
- foreach — Apply a procedure on option value
- collect — Apply partial pattern match on optional value
- filter — An optional value satisfies predicate
- filterNot — An optional value doesn't satisfy predicate
- exists — Apply predicate on optional value, or false if empty
- forall — Apply predicate on optional value, or true if empty
- contains — Checks if value equals optional value, or false if empty
- zip — Combine two optional values to make a paired optional value
- unzip — Split an optional pair to two optional values
- unzip3 — Split an optional triple to three optional values
- toList — Unary list of optional value, otherwise the empty listA less-idiomatic way to use Option values is via pattern matching:
val nameMaybe = request getParameter "name"
nameMaybe match {
case Some(name) =>
println(name.trim.toUppercase)
case None =>
println("No name value")
}
Interacting with code that can occasionally return null can be
safely wrapped in Option to become
None
and Some otherwise. val abc = new java.util.HashMap[Int, String]
abc.put(1, "A")
bMaybe = Option(abc.get(2))
bMaybe match {
case Some(b) =>
println(s"Found $b")
case None =>
println("Not found")
}
trait Serializable
trait Product
trait Equals
trait IterableOnce[A]
class Object
trait Matchable
class Any
Type members
Classlikes
We need a whole WithFilter class to honor the "doesn't create a new
collection" contract even though it seems unlikely to matter much in a
collection with max size 1.
- Source
- (source)
Value members
Methods
@deprecated("Iterable.seq always returns the iterable itself", "2.13.0")
Implicitly added by option2Iterable
- Source
- (source)
Implicitly added by option2Iterable
Analogous to
zip
except that the elements in each collection are not consumed until a strict operation is
invoked on the returned LazyZip2
decorator.Calls to
lazyZip
can be chained to support higher arities (up to 4) without incurring the expense of
constructing and deconstructing intermediary tuples.val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)
- Type Params
- B
-
the type of the second element in each eventual pair
- Value Params
- that
-
the iterable providing the second element of each eventual pair
- Returns
-
a decorator
LazyZip2
that allows strict operations to be performed on the lazily evaluated pairs or chained calls tolazyZip
. Implicit conversion toIterable[(A, B)]
is also supported. - Source
- (source)
Returns true if the option is
None
, false otherwise.This is equivalent to:
option match {
case Some(_) => false
case None => true
}
- Source
- (source)
Returns the option's value.
This is equivalent to:
option match {
case Some(x) => x
case None => throw new Exception
}
- Throws
- NoSuchElementException
- NoSuchElementException
- Note
- The option must be nonempty.
- Source
- (source)
Returns the option's value if the option is nonempty, otherwise
return the result of evaluating
default
.This is equivalent to:
option match {
case Some(x) => x
case None => default
}
- Value Params
- default
-
the default expression.
- Source
- (source)
Returns the option's value if it is nonempty,
or
null
if it is empty.Although the use of null is discouraged, code written to use
Option must often interface with code that expects and returns nulls.
This is equivalent to:
option match {
case Some(x) => x
case None => null
}
- Example
val initialText: Option[String] = getInitialText val textField = new JComponent(initialText.orNull,20)
- Source
- (source)
This is equivalent to:
option match {
case Some(x) => f(x)
case None => ifEmpty
}
This is also equivalent to:
option map f getOrElse ifEmpty
- Value Params
- f
-
the function to apply if nonempty.
- ifEmpty
-
the expression to evaluate if empty.
- Source
- (source)
This is equivalent to:
option match {
case Some(x) => f(x)
case None => None
}
- Value Params
- f
-
the function to apply
- See also
- mapforeach
- Source
- (source)
Returns false if the option is
None
, true otherwise.This is equivalent to:
option match {
case Some(_) => true
case None => false
}
- Note
- Implemented here to avoid the implicit conversion to Iterable.
- Source
- (source)
Necessary to keep Option from being implicitly converted to
collection.Iterable in
for
comprehensions.
- Source
- (source)
Tests whether the option contains a given value as an element.
This is equivalent to:
option match {
case Some(x) => x == elem
case None => false
}
- Value Params
- elem
-
the element to test.
- Returns
-
true
if the option has an element that is equal (as determined by==
) toelem
,false
otherwise. - Example
// Returns true because Some instance contains string "something" which equals "something". Some("something") contains "something" // Returns false because "something" != "anything". Some("something") contains "anything" // Returns false when method called on None. None contains "anything"
- Source
- (source)
Apply the given procedure
f
to the option's value,
if it is nonempty. Otherwise, do nothing.This is equivalent to:
option match {
case Some(x) => f(x)
case None => ()
}
- Value Params
- f
-
the procedure to apply.
- See also
- mapflatMap
- Source
- (source)
- Value Params
- pf
-
the partial function.
- Returns
- Example
// Returns Some(HTTP) because the partial function covers the case. Some("http") collect {case "http" => "HTTP"} // Returns None because the partial function doesn't cover the case. Some("ftp") collect {case "http" => "HTTP"} // Returns None because the option is empty. There is no value to pass to the partial function. None collect {case value => value}
- Source
- (source)
Returns a Some formed from this option and another option
by combining the corresponding elements in a pair.
If either of the two options is empty,
None
is returned.This is equivalent to:
(option1, option2) match {
case (Some(x), Some(y)) => Some((x, y))
case _ => None
}
- Value Params
- that
-
the options which is going to be zipped
- Example
// Returns Some(("foo", "bar")) because both options are nonempty. Some("foo") zip Some("bar") // Returns None because `that` option is empty. Some("foo") zip None // Returns None because `this` option is empty. None zip Some("bar")
- Source
- (source)
Converts an Option of a pair into an Option of the first element and an Option of the second element.
This is equivalent to:
option match {
case Some((x, y)) => (Some(x), Some(y))
case _ => (None, None)
}
- Type Params
- A1
-
the type of the first half of the element pair
- A2
-
the type of the second half of the element pair
- Value Params
- asPair
-
an implicit conversion which asserts that the element type of this Option is a pair.
- Returns
-
a pair of Options, containing, respectively, the first and second half of the element pair of this Option.
- Source
- (source)
Converts an Option of a triple into three Options, one containing the element from each position of the triple.
This is equivalent to:
option match {
case Some((x, y, z)) => (Some(x), Some(y), Some(z))
case _ => (None, None, None)
}
- Type Params
- A1
-
the type of the first of three elements in the triple
- A2
-
the type of the second of three elements in the triple
- A3
-
the type of the third of three elements in the triple
- Value Params
- asTriple
-
an implicit conversion which asserts that the element type of this Option is a triple.
- Returns
-
a triple of Options, containing, respectively, the first, second, and third elements from the element triple of this Option.
- Source
- (source)
Returns a util.Left containing the given
argument
left
if this Option is empty, or
a util.Right containing this Option's value if
this is nonempty.This is equivalent to:
option match {
case Some(x) => Right(x)
case None => Left(left)
}
- Value Params
- left
-
the expression to evaluate and return if this is empty
- See also
- toLeft
- Source
- (source)
Returns a util.Right containing the given
argument
right
if this is empty, or
a util.Left containing this Option's value
if this Option is nonempty.This is equivalent to:
option match {
case Some(x) => Left(x)
case None => Right(right)
}
- Value Params
- right
-
the expression to evaluate and return if this is empty
- See also
- toRight
- Source
- (source)
Inherited methods
Implicitly added by option2Iterable
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]
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Selects all elements except last n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Value Params
- n
-
the number of elements to drop from this iterable collection.
- Returns
-
a iterable collection consisting of all elements of this iterable collection except the last
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements. Ifn
is negative, don't drop any elements. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
The last element of this iterable collection.
- Throws
- NoSuchElementException
- NoSuchElementException
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use foldLeft instead of /:", "2.13.0") @inline
Implicitly added by option2Iterable
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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)
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Partitions this iterable collection into a map of iterable collections according to a discriminator function
key
.
Each element in a group is transformed into a value of type B
using the value
function.It is equivalent to
groupBy(key).mapValues(_.map(f))
, but more efficient.case class User(name: String, age: Int)
def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
users.groupMap(_.age)(_.name)
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Type Params
- B
-
the type of values returned by the transformation function
- K
-
the type of keys returned by the discriminator function
- Value Params
- f
-
the element transformation function
- key
-
the discriminator function
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Returns a iterable collection formed from this iterable collection and another iterable collection
by combining corresponding elements in pairs.
If one of the two collections is longer than the other, its remaining elements are ignored.
- Type Params
- B
-
the type of the second half of the returned pairs
- Value Params
- that
-
The iterable providing the second half of each result pair
- Returns
-
a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and
that
. The length of the returned collection is the minimum of the lengths of this iterable collection andthat
. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Applies a function
f
to each element of the iterable collection and returns a pair of iterable collections: the first one
made of those values returned by f
that were wrapped in scala.util.Left, and the second
one made of those wrapped in scala.util.Right.Example:
val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap {
case i: Int => Left(i)
case s: String => Right(s)
}
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three))
- Type Params
- A1
-
the element type of the first resulting collection
- A2
-
the element type of the second resulting collection
- Value Params
- f
-
the 'split function' mapping the elements of this iterable collection to an scala.util.Either
- Returns
-
a pair of iterable collections: the first one made of those values returned by
f
that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right. - Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use .to(LazyList) instead of .toStream", "2.13.0") @inline
Implicitly added by option2Iterable
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Apply
f
to each element for its side effects
Note: [U] parameter needed to help scalac's type inference.
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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 innum
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Produces a collection containing cumulative results of applying the operator going right to left.
The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
- Type Params
- B
-
the type of the elements in the resulting collection
- Value Params
- op
-
the binary operator applied to the intermediate result and the element
- z
-
the initial value
- Returns
-
collection with intermediate results
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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 andp(x, y)
istrue
for all corresponding elementsx
of this iterator andy
ofthat
, otherwisefalse
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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 andz
, orz
if this collection is empty. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Convert collection to array.
Implementation note: DO NOT call Array.from from this method.
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Iterates over the inits of this iterable collection. The first value will be this
iterable collection and the final one will be an empty iterable collection, with the intervening
values the results of successive applications of
init
. Note: Even when applied to a view or a lazy collection it will always force the elements.
- Returns
-
an iterator over all the inits of this iterable collection
- Example
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Groups elements in fixed size blocks by passing a "sliding window"
over them (as opposed to partitioning them, as is done in grouped.)
The returned iterator will be empty when called on an empty collection.
The last element the iterator produces may be smaller than the window
size when the original collection isn't exhausted by the window before
it and its last element isn't skipped by the step before it.
- Value Params
- size
-
the number of elements per group
- step
-
the distance between the first elements of successive groups
- Returns
-
An iterator producing iterable collections of size
size
, except the last element (which may be the only element) will be smaller if there are fewer thansize
elements remaining to be grouped. - See also
- scala.collection.Iterator, method
sliding
- Example
List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))
List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Groups elements in fixed size blocks by passing a "sliding window"
over them (as opposed to partitioning them, as is done in
grouped
.)An empty collection returns an empty iterator, and a non-empty
collection containing fewer elements than the window size returns
an iterator that will produce the original collection as its only
element.
- Value Params
- size
-
the number of elements per group
- Returns
-
An iterator producing iterable collections of size
size
, except for a non-empty collection with less thansize
elements, which returns an iterator that produces the source collection itself as its only element. - See also
- scala.collection.Iterator, method
sliding
- Example
List().sliding(2) = empty iterator
List(1).sliding(2) = Iterator(List(1))
List(1, 2).sliding(2) = Iterator(List(1, 2))
List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
The rest of the collection without its first element.
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("`aggregate` is not relevant for sequential collections. Use `foldLeft(z)(seqop)` instead.", "2.13.0")
Implicitly added by option2Iterable
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Transposes this iterable collection of iterable collections into
a iterable collection of iterable collections.
The resulting collection's type will be guided by the
static type of iterable collection. For example:
val xs = List(
Set(1, 2, 3),
Set(4, 5, 6)).transpose
// xs == List(
// List(1, 4),
// List(2, 5),
// List(3, 6))
val ys = Vector(
List(1, 2, 3),
List(4, 5, 6)).transpose
// ys == Vector(
// Vector(1, 4),
// Vector(2, 5),
// Vector(3, 6))
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Type Params
- B
-
the type of the elements of each iterable collection.
- Value Params
- asIterable
-
an implicit conversion which asserts that the element type of this iterable collection is an
Iterable
.
- Returns
-
a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.
- Throws
- IllegalArgumentException
- IllegalArgumentException
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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 valuez
on the left:op(...op(z, x1), x2, ..., xn)
wherex1, ..., xn
are the elements of this collection. Returnsz
if this collection is empty. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Creates a non-strict filter of this iterable collection.
Note: the difference between
c filter p
and c withFilter p
is that
the former creates a new collection, whereas the latter only
restricts the domain of subsequent map
, flatMap
, foreach
,
and withFilter
operations. 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 object of class
WithFilter
, which supportsmap
,flatMap
,foreach
, andwithFilter
operations. All these operations apply to those elements of this iterable collection which satisfy the predicatep
. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
The size of this collection.
Note: will not terminate for infinite-sized collections.
- Returns
-
the number of elements in this collection.
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use toIterable instead", "2.13.0")
Implicitly added by option2Iterable
Converts this iterable collection to an unspecified Iterable. Will return
the same collection if this instance is already Iterable.
- Returns
-
An Iterable containing all elements of this iterable collection.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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 valuez
on the right:op(x1, op(x2, ... op(xn, z)...))
wherex1, ..., xn
are the elements of this collection. Returnsz
if this collection is empty. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
- Returns
-
This collection as a
Seq[A]
. This is equivalent toto(Seq)
but might be faster. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0")
Implicitly added by option2Iterable
Tests whether the collection is not empty.
- Returns
-
true
if the collection contains at least one element,false
otherwise. - Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)", "2.13.0")
Implicitly added by option2Iterable
Tests whether this collection is known to have a finite size.
All strict collections are known to have finite size. For a non-strict
collection such as
Stream
, the predicate returns true
if all
elements have been computed. It returns false
if the stream is
not yet evaluated to the end. Non-empty Iterators usually return
false
even if they were created from a collection with a known
finite size.Note: many collection methods will not work on collections of infinite sizes.
The typical failure mode is an infinite loop. These methods always attempt a
traversal without checking first that
hasDefiniteSize
returns true
.
However, checking hasDefiniteSize
can provide an assurance that size is
well-defined and non-termination is not a concern.
- Returns
-
true
if this collection is known to have finite size,false
otherwise. - See also
- method
knownSize
for a more useful alternative - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
A pair of, first, all elements that satisfy predicate
p
and, second,
all elements that do not. Interesting because it splits a collection in two.The default implementation provided here needs to traverse the collection twice.
Strict collections have an overridden version of
partition
in StrictOptimizedIterableOps
,
which requires only a single traversal.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Compares the size of this iterable collection to the size of another
Iterable
.
- Value Params
- that
-
the
Iterable
whose size is compared with this iterable collection's size.
- Returns
-
A value
x
wherex < 0 if this.size < that.size x == 0 if this.size == that.size x > 0 if this.size > that.size
The method as implemented here does not callsize
directly; its running time isO(this.size min that.size)
instead ofO(this.size + that.size)
. The method should be overridden if computingsize
is cheap andknownSize
returns-1
. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Compares the size of this iterable collection to a test value.
- Value Params
- otherSize
-
the test value that gets compared with the size.
- Returns
-
A value
x
wherex < 0 if this.size < otherSize x == 0 if this.size == otherSize x > 0 if this.size > otherSize
The method as implemented here does not callsize
directly; its running time isO(size min otherSize)
instead ofO(size)
. The method should be overridden if computingsize
is cheap andknownSize
returns-1
. - See also
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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)...))
wherex1, ..., xn
are the elements of this collection. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use `dest ++= coll` instead", "2.13.0") @inline
Implicitly added by option2Iterable
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Tests whether the collection is empty.
Note: Implementations in subclasses that are not repeatedly traversable must take
care not to consume any elements when
isEmpty
is called.
- Returns
-
true
if the collection contains no elements,false
otherwise. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
- Returns
-
The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
- Inhertied from
- IterableOnce
- Source
- (source)
Implicitly added by option2Iterable
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
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Type Params
- K
-
the type of keys returned by the discriminator function.
- Value Params
- f
-
the discriminator function.
- Returns
-
A map from keys to iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
That is, every keyk
is bound to a iterable collection of those elementsx
for whichf(x)
equalsk
. - Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use .iterator instead of .toIterator", "2.13.0") @inline
Implicitly added by option2Iterable
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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
, orNone
if none exists. - Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use iterableFactory instead", "2.13.0") @deprecatedOverriding("Use iterableFactory instead", "2.13.0") @inline
Implicitly added by option2Iterable
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Selects the last n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Value Params
- n
-
the number of elements to take from this iterable collection.
- Returns
-
a iterable collection consisting only of the last
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements. Ifn
is negative, returns an empty iterable collection. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Converts this iterable collection of pairs into two collections of the first and second
half of each pair.
val xs = Iterable(
(1, "one"),
(2, "two"),
(3, "three")).unzip
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three))
- Type Params
- A1
-
the type of the first half of the element pairs
- A2
-
the type of the second half of the element pairs
- Value Params
- asPair
-
an implicit conversion which asserts that the element type of this iterable collection is a pair.
- Returns
-
a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Partitions elements in fixed size iterable collections.
- Value Params
- size
-
the number of elements per group
- Returns
-
An iterator producing iterable collections of size
size
, except the last will be less than sizesize
if the elements don't divide evenly. - See also
- scala.collection.Iterator, method
grouped
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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 innum
. - Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use foldRight instead of :\\", "2.13.0") @inline
Implicitly added by option2Iterable
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Computes a prefix scan of the elements of the collection.
Note: The neutral element
z
may be applied more than once.
- Type Params
- B
-
element type of the resulting collection
- Value Params
- op
-
the associative operator for the scan
- z
-
neutral element for the operator
op
- Returns
-
a new iterable collection containing the prefix scan of the elements in this iterable collection
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
the first element of this iterable collection if it is nonempty,
None
if it is empty. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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 predicatep
holds for all elements of this collection, otherwisefalse
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Alias for
concat
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Iterator can be used only once
- Inhertied from
- IterableOnce
- Source
- (source)
Implicitly added by option2Iterable
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.
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
Implicitly added by option2Iterable
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.
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
Implicitly added by option2Iterable
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.
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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 stringsep
. - Example
List(1, 2, 3).mkString("|") = "1|2|3"
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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 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)"
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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
Long
a scala.collection.LongStepper is returned -
For 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.
- Inhertied from
- IterableOnce
- Source
- (source)
Implicitly added by option2Iterable
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
the first element of this iterable collection.
- Throws
- NoSuchElementException
- NoSuchElementException
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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, andNone
otherwise. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Partitions this iterable collection into a map according to a discriminator function
key
. All the values that
have the same discriminator are then transformed by the f
function and then reduced into a
single value with the reduce
function.It is equivalent to
groupBy(key).mapValues(_.map(f).reduce(reduce))
, but more efficient.def occurrences[A](as: Seq[A]): Map[A, Int] =
as.groupMapReduce(identity)(_ => 1)(_ + _)
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the
right hand operand. The element type of the iterable collection is the most specific superclass encompassing
the element types of the two operands.
- Type Params
- B
-
the element type of the returned collection.
- Value Params
- suffix
-
the traversable to append.
- Returns
-
a new iterable collection which contains all elements of this iterable collection followed by all elements of
suffix
. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
The initial part of the collection without its last element.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
These operations are implemented in terms of
sizeCompare(Int)
, and
allow the following more readable usages:this.sizeIs < size // this.sizeCompare(size) < 0
this.sizeIs <= size // this.sizeCompare(size) <= 0
this.sizeIs == size // this.sizeCompare(size) == 0
this.sizeIs != size // this.sizeCompare(size) != 0
this.sizeIs >= size // this.sizeCompare(size) >= 0
this.sizeIs > size // this.sizeCompare(size) > 0
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use coll instead of repr in a collection implementation, use the collection value itself from the outside", "2.13.0")
Implicitly added by option2Iterable
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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)
wherex1, ..., xn
are the elements of this collection. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
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 predicatep
is satisfied by at least one element of this collection, otherwisefalse
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Takes longest prefix of elements that satisfy a predicate.
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
-
the longest prefix of this iterable collection whose elements all satisfy the predicate
p
. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Converts this iterable collection of triples into three collections of the first, second,
and third element of each triple.
val xs = Iterable(
(1, "one", '1'),
(2, "two", '2'),
(3, "three", '3')).unzip3
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three),
// Iterable(1, 2, 3))
- Type Params
- A1
-
the type of the first member of the element triples
- A2
-
the type of the second member of the element triples
- A3
-
the type of the third member of the element triples
- Value Params
- asTriple
-
an implicit conversion which asserts that the element type of this iterable collection is a triple.
- Returns
-
a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
Returns a iterable collection formed from this iterable collection and another iterable collection
by combining corresponding elements in pairs.
If one of the two collections is shorter than the other,
placeholder elements are used to extend the shorter collection to the length of the longer.
- Value Params
- that
-
the iterable providing the second half of each result pair
- thatElem
-
the element to be used to fill up the result if
that
is shorter than this iterable collection. - thisElem
-
the element to be used to fill up the result if this iterable collection is shorter than
that
.
- Returns
-
a new collection of type
That
containing pairs consisting of corresponding elements of this iterable collection andthat
. The length of the returned collection is the maximum of the lengths of this iterable collection andthat
. If this iterable collection is shorter thanthat
,thisElem
values are used to pad the result. Ifthat
is shorter than this iterable collection,thatElem
values are used to pad the result. - Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use ++ instead of ++: for collections of type Iterable", "2.13.0")
Implicitly added by option2Iterable
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use .view.slice(from, until) instead of .view(from, until)", "2.13.0")
Implicitly added by option2Iterable
A view over a slice of the elements of this collection.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
A view over the elements of this collection.
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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. - Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Iterates over the tails of this iterable collection. The first value will be this
iterable collection and the final one will be an empty iterable collection, with the intervening
values the results of successive applications of
tail
.
- Returns
-
an iterator over all the tails of this iterable collection
- Example
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
- Inhertied from
- IterableOps
- Source
- (source)
Implicitly added by option2Iterable
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
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Implicitly added by option2Iterable
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
the last element of this iterable collection$ if it is nonempty,
None
if it is empty. - Inhertied from
- IterableOps
- Source
- (source)
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
Long
a scala.collection.LongStepper is returned -
For 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.
- Inhertied from
- IterableOnce
- Source
- (source)
A method that should be called from every well-designed equals method
that is open to be overridden in a subclass. See
Programming in Scala,
Chapter 28 for discussion and design.
The nth element of this product, 0-based. In other words, for a
product
A(x1, ..., xk)
, returns x(n+1)
where 0 <= n < k
.
- Value Params
- n
-
the index of the element to return
- Returns
-
the element
n
elements after the first element - Throws
- IndexOutOfBoundsException
- IndexOutOfBoundsException
- Inhertied from
- Product
- Source
- (source)
The name of the nth element of this product, 0-based.
In the default implementation, an empty string.
- Value Params
- n
-
the index of the element name to return
- Returns
-
the name of the specified element
- Throws
- IndexOutOfBoundsException
- IndexOutOfBoundsException
- Inhertied from
- Product
- Source
- (source)