None
This case object represents non-existent values.
Attributes
- Source
- Option.scala
- Graph
- Supertypes
- traitSerializabletraitProducttraitEqualstraitIterableOnce[Nothing]classObjecttraitMatchableclassAnyShow all
- Self type
- None.type
Members list
Type members
Inherited 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.
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.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
- Supertypes
Value members
Concrete methods
Returns the option's value.
Returns the option's value.
This is equivalent to:
option match { case Some(x) => x case None => throw new Exception}Attributes
- Throws
NoSuchElementExceptionif the option is empty.
- Note
The option must be nonempty.
- Source
- Option.scala
Inherited methods
Returns ascala.Some containing the result of applyingpf to thisscala.Option's contained value,if this option is nonemptyandpf is defined for that value.
Returns ascala.Some containing the result of applyingpf to thisscala.Option's contained value,if this option is nonemptyandpf is defined for that value. ReturnsNone otherwise.
Value parameters
- pf
the partial function.
Attributes
- Returns
the result of applying
pfto thisscala.Option's value (if possible), orNone.- 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}- Inherited from:
- Option
- Source
- Option.scala
Tests whether the option contains a given value as an element.
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 parameters
- elem
the element to test.
Attributes
- Returns
trueif the option has an element that is equal (as determined by==) toelem,falseotherwise.- 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"- Inherited from:
- Option
- Source
- Option.scala
Returns true if this option is nonemptyand the predicatep returns true when applied to thisscala.Option's value.
Returns true if this option is nonemptyand the predicatep returns true when applied to thisscala.Option's value. Otherwise, returns false.
This is equivalent to:
option match { case Some(x) => p(x) case None => false}Value parameters
- p
the predicate to test
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns thisscala.Option if it is nonemptyand applying the predicatep to thisscala.Option's value returns true.
Returns thisscala.Option if it is nonemptyand applying the predicatep to thisscala.Option's value returns true. Otherwise, returnNone.
This is equivalent to:
option match { case Some(x) if p(x) => Some(x) case _ => None}Value parameters
- p
the predicate used for testing.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns thisscala.Option if it is nonemptyand applying the predicatep to thisscala.Option's value returns false.
Returns thisscala.Option if it is nonemptyand applying the predicatep to thisscala.Option's value returns false. Otherwise, returnNone.
This is equivalent to:
option match { case Some(x) if !p(x) => Some(x) case _ => None}Value parameters
- p
the predicate used for testing.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns the result of applyingf to thisscala.Option's value if thisscala.Option is nonempty.
Returns the result of applyingf to thisscala.Option's value if thisscala.Option is nonempty. ReturnsNone if thisscala.Option is empty. Slightly different frommap in thatf is expected to return anscala.Option (which could beNone).
This is equivalent to:
option match { case Some(x) => f(x) case None => None}Value parameters
- f
the function to apply
Attributes
- See also
map
foreach
- Inherited from:
- Option
- Source
- Option.scala
Returns the nestedscala.Option value if it is nonempty.
Returns the nestedscala.Option value if it is nonempty. Otherwise, returnNone.
This is equivalent to:
option match { case Some(Some(b)) => Some(b) case _ => None}Value parameters
- ev
an implicit conversion that asserts that the value is also anscala.Option.
Attributes
- See also
flatMap
- Example
Some(Some("something")).flatten- Inherited from:
- Option
- Source
- Option.scala
Returns the result of applyingf to thisscala.Option's value if thescala.Option is nonempty.
Returns the result of applyingf to thisscala.Option's value if thescala.Option is nonempty. Otherwise, evaluates expressionifEmpty.
This is equivalent to:
option match { case Some(x) => f(x) case None => ifEmpty}This is also equivalent to:
option map f getOrElse ifEmptyValue parameters
- f
the function to apply if nonempty.
- ifEmpty
the expression to evaluate if empty.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns true if this option is emptyor the predicatep returns true when applied to thisscala.Option's value.
Returns true if this option is emptyor the predicatep returns true when applied to thisscala.Option's value.
This is equivalent to:
option match { case Some(x) => p(x) case None => true}Value parameters
- p
the predicate to test
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Apply the given proceduref to the option's value, if it is nonempty.
Apply the given proceduref 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 parameters
- f
the procedure to apply.
Attributes
- See also
map
flatMap
- Inherited from:
- Option
- Source
- Option.scala
Returns the option's value if the option is nonempty, otherwise return the result of evaluatingdefault.
Returns the option's value if the option is nonempty, otherwise return the result of evaluatingdefault.
This is equivalent to:
option match { case Some(x) => x case None => default}Value parameters
- default
the default expression.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns true if the option is an instance ofscala.Some, false otherwise.
Returns true if the option is an instance ofscala.Some, false otherwise.
This is equivalent to:
option match { case Some(_) => true case None => false}Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns true if the option isNone, false otherwise.
Returns true if the option isNone, false otherwise.
This is equivalent to:
option match { case Some(_) => false case None => true}Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns a singleton iterator returning thescala.Option's value if it is nonempty, or an empty iterator if the option is empty.
Returns a singleton iterator returning thescala.Option's value if it is nonempty, or an empty iterator if the option is empty.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
The number of elements in this option, if it can be cheaply computed, -1 otherwise.
The number of elements in this option, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
Attributes
- Definition Classes
- Inherited from:
- Option
- Source
- Option.scala
Returns ascala.Some containing the result of applyingf to thisscala.Option's value if thisscala.Option is nonempty.
Returns ascala.Some containing the result of applyingf to thisscala.Option's value if thisscala.Option is nonempty. Otherwise returnNone.
This is equivalent to:
option match { case Some(x) => Some(f(x)) case None => None}Value parameters
- f
the function to apply
Attributes
- See also
flatMap
foreach
- Note
This is similar to
flatMapexcept here,fdoes not need to wrap its result in anscala.Option.- Inherited from:
- Option
- Source
- Option.scala
Returns false if the option isNone, true otherwise.
Returns false if the option isNone, true otherwise.
This is equivalent to:
option match { case Some(_) => true case None => false}Attributes
- Note
Implemented here to avoid the implicit conversion to Iterable.
- Inherited from:
- Option
- Source
- Option.scala
Returns thisscala.Option if it is nonempty, otherwise return the result of evaluatingalternative.
Returns thisscala.Option if it is nonempty, otherwise return the result of evaluatingalternative.
This is equivalent to:
option match { case Some(x) => Some(x) case None => alternative}Value parameters
- alternative
the alternative expression.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns the option's value if it is nonempty, ornull if it is empty.
Returns the option's value if it is nonempty, ornull if it is empty.
Although the use of null is discouraged, code written to usescala.Option must often interface with code that expects and returns nulls.
This is equivalent to:
option match { case Some(x) => x case None => null}Attributes
- Example
val initialText: Option[String] = getInitialTextval textField = new JComponent(initialText.orNull,20)- Inherited from:
- Option
- Source
- Option.scala
An iterator over the names of all the elements of this product.
An iterator over the names of all the elements of this product.
Attributes
- Inherited from:
- Product
- Source
- Product.scala
An iterator over all the elements of this product.
An iterator over all the elements of this product.
Attributes
- Returns
in the default implementation, an
Iterator[Any]- Inherited from:
- Product
- Source
- Product.scala
Returns ascala.collection.Stepper for the elements of this collection.
Returns ascala.collection.Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, seescala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicitscala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
For collections of
Int,Short,ByteorChar, anscala.collection.IntStepper is returnedFor collections of
DoubleorFloat, ascala.collection.DoubleStepper is returnedFor collections of
Longascala.collection.LongStepper is returnedFor any other element type, anscala.collection.AnyStepper is returned
Note that this method is overridden in subclasses and the return type is refined toS with EfficientSplit, for examplescala.collection.IndexedSeqOps.stepper. For Steppers marked withscala.collection.Stepper.EfficientSplit, the converters inscala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.
Attributes
- Inherited from:
- IterableOnce
- Source
- IterableOnce.scala
Returns ascala.util.Right containing the given argumentright if this is empty, or ascala.util.Left containing thisscala.Option's value if thisscala.Option is nonempty.
Returns ascala.util.Right containing the given argumentright if this is empty, or ascala.util.Left containing thisscala.Option's value if thisscala.Option is nonempty.
This is equivalent to:
option match { case Some(x) => Left(x) case None => Right(right)}Value parameters
- right
the expression to evaluate and return if this is empty
Attributes
- See also
toRight
- Inherited from:
- Option
- Source
- Option.scala
Returns a singleton list containing thescala.Option's value if it is nonempty, or the empty list if thescala.Option is empty.
Returns a singleton list containing thescala.Option's value if it is nonempty, or the empty list if thescala.Option is empty.
This is equivalent to:
option match { case Some(x) => List(x) case None => Nil}Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns ascala.util.Left containing the given argumentleft if thisscala.Option is empty, or ascala.util.Right containing thisscala.Option's value if this is nonempty.
Returns ascala.util.Left containing the given argumentleft if thisscala.Option is empty, or ascala.util.Right containing thisscala.Option's value if this is nonempty.
This is equivalent to:
option match { case Some(x) => Right(x) case None => Left(left)}Value parameters
- left
the expression to evaluate and return if this is empty
Attributes
- See also
toLeft
- Inherited from:
- Option
- Source
- Option.scala
Converts an Option of a pair into an Option of the first element and an Option of the second element.
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 parameters
- A1
the type of the first half of the element pair
- A2
the type of the second half of the element pair
Value parameters
- asPair
an implicit conversion which asserts that the element type of this Option is a pair.
Attributes
- Returns
a pair of Options, containing, respectively, the first and second half of the element pair of this Option.
- Inherited from:
- Option
- Source
- Option.scala
Converts an Option of a triple into three Options, one containing the element from each position of the triple.
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 parameters
- 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 parameters
- asTriple
an implicit conversion which asserts that the element type of this Option is a triple.
Attributes
- Returns
a triple of Options, containing, respectively, the first, second, and third elements from the element triple of this Option.
- Inherited from:
- Option
- Source
- Option.scala
Necessary to keepscala.Option from being implicitly converted toscala.collection.Iterable infor comprehensions.
Necessary to keepscala.Option from being implicitly converted toscala.collection.Iterable infor comprehensions.
Attributes
- Inherited from:
- Option
- Source
- Option.scala
Returns ascala.Some formed from this option and another option by combining the corresponding elements in a pair.
Returns ascala.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 parameters
- that
the options which is going to be zipped
Attributes
- 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")- Inherited from:
- Option
- Source
- Option.scala