None

object None extends Option[Nothing] with Product with Serializable

This case object represents non-existent values.

Annotations: @SerialVersionUID()
Source: Option.scala
Since: 1.0

Linear Supertypes

Option[Nothing], Serializable, java.io.Serializable, Product, Equals, AnyRef, Any

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Type Members

class WithFilter extends AnyRef
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.
Definition Classes
Option

Value Members

final def !=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
returns
true if !(this == that), false otherwise.
Definition Classes
AnyRef → Any
final def ##(): Int
Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
returns
a hash value consistent with ==
Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0
Cast the receiver object to be of type T0.
Cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.
returns
the receiver object.
Definition Classes
Any
Exceptions thrown
ClassCastException if the receiver object is not an instance of the erasure of type T0.
def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
returns
a copy of the receiver object.
Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@native() @throws(classOf[java.lang.CloneNotSupportedException])
Note
not specified by SLS as a member of AnyRef
final def collect[B](pf: PartialFunction[Nothing, B]): Option[B]
Returns a scala.Some containing the result of applying pf to this scala.Option's contained value, if this option is nonempty and pf is defined for that value.
Returns a scala.Some containing the result of applying pf to this scala.Option's contained value, if this option is nonempty and pf is defined for that value. Returns None otherwise.
pf
the partial function.
returns
the result of applying pf to this scala.Option's value (if possible), or None.
Definition Classes
Option
Annotations
@inline()
Example:
1. // 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}
final def contains[A1 >: Nothing](elem: A1): Boolean
Tests whether the option contains a given value as an element.
Tests whether the option contains a given value as an element.
elem
the element to test.
returns
true if the option has an element that is equal (as determined by ==) to elem, false otherwise.
Definition Classes
Option
Example:
1. // 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"
final def eq(arg0: AnyRef): Boolean
Tests whether the argument (that) is a reference to the receiver object (this).
Tests whether the argument (that) is a reference to the receiver object (this).
The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:
- It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
- For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
- null.eq(null) returns true.
When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
returns
true if the argument is a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
def equals(arg0: Any): Boolean
The equality method for reference types.
The equality method for reference types. Default implementation delegates to eq.
See also equals in scala.Any.
returns
true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes
AnyRef → Any
final def exists(p: (Nothing) ⇒ Boolean): Boolean
Returns true if this option is nonempty and the predicate p returns true when applied to this scala.Option's value.
Returns true if this option is nonempty and the predicate p returns true when applied to this scala.Option's value. Otherwise, returns false.
p
the predicate to test
Definition Classes
Option
Annotations
@inline()
final def filter(p: (Nothing) ⇒ Boolean): Option[Nothing]
Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns true.
Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns true. Otherwise, return None.
p
the predicate used for testing.
Definition Classes
Option
Annotations
@inline()
final def filterNot(p: (Nothing) ⇒ Boolean): Option[Nothing]
Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns false.
Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns false. Otherwise, return None.
p
the predicate used for testing.
Definition Classes
Option
Annotations
@inline()
def finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
Note
not specified by SLS as a member of AnyRef
final def flatMap[B](f: (Nothing) ⇒ Option[B]): Option[B]
Returns the result of applying f to this scala.Option's value if this scala.Option is nonempty.
Returns the result of applying f to this scala.Option's value if this scala.Option is nonempty. Returns None if this scala.Option is empty. Slightly different from map in that f is expected to return an scala.Option (which could be None).
f
the function to apply
Definition Classes
Option
Annotations
@inline()
See also
map
foreach
def flatten[B](implicit ev: <:<[Nothing, Option[B]]): Option[B]
Definition Classes
Option
final def fold[B](ifEmpty: ⇒ B)(f: (Nothing) ⇒ B): B
Returns the result of applying f to this scala.Option's value if the scala.Option is nonempty.
Returns the result of applying f to this scala.Option's value if the scala.Option is nonempty. Otherwise, evaluates expression ifEmpty.
ifEmpty
the expression to evaluate if empty.
f
the function to apply if nonempty.
Definition Classes
Option
Annotations
@inline()
Note
This is equivalent to scala.Option map f getOrElse ifEmpty.
final def forall(p: (Nothing) ⇒ Boolean): Boolean
Returns true if this option is empty or the predicate p returns true when applied to this scala.Option's value.
Returns true if this option is empty or the predicate p returns true when applied to this scala.Option's value.
p
the predicate to test
Definition Classes
Option
Annotations
@inline()
final def foreach[U](f: (Nothing) ⇒ U): Unit
Apply the given procedure f to the option's value, if it is nonempty.
Apply the given procedure f to the option's value, if it is nonempty. Otherwise, do nothing.
f
the procedure to apply.
Definition Classes
Option
Annotations
@inline()
See also
map
flatMap
def get: Nothing
Returns the option's value.
Returns the option's value.
Definition Classes
None → Option
Exceptions thrown
java.util.NoSuchElementException if the option is empty.
Note
The option must be nonempty.
final def getClass(): Class[_]
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
returns
a class object corresponding to the runtime type of the receiver.
Definition Classes
AnyRef → Any
Annotations
@native()
final def getOrElse[B >: Nothing](default: ⇒ B): B
Returns the option's value if the option is nonempty, otherwise return the result of evaluating default.
Returns the option's value if the option is nonempty, otherwise return the result of evaluating default.
default
the default expression.
Definition Classes
Option
Annotations
@inline()
def isDefined: Boolean
Returns true if the option is an instance of scala.Some, false otherwise.
Returns true if the option is an instance of scala.Some, false otherwise.
Definition Classes
Option
def isEmpty: Boolean
Returns true if the option is None, false otherwise.
Returns true if the option is None, false otherwise.
Definition Classes
None → Option
final def isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is T0.
Test whether the dynamic type of the receiver object is T0.
Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.
returns
true if the receiver object is an instance of erasure of type T0; false otherwise.
Definition Classes
Any
def iterator: Iterator[Nothing]
Returns a singleton iterator returning the scala.Option's value if it is nonempty, or an empty iterator if the option is empty.
Returns a singleton iterator returning the scala.Option's value if it is nonempty, or an empty iterator if the option is empty.
Definition Classes
Option
final def map[B](f: (Nothing) ⇒ B): Option[B]
Returns a scala.Some containing the result of applying f to this scala.Option's value if this scala.Option is nonempty.
Returns a scala.Some containing the result of applying f to this scala.Option's value if this scala.Option is nonempty. Otherwise return None.
f
the function to apply
Definition Classes
Option
Annotations
@inline()
Note
This is similar to flatMap except here, f does not need to wrap its result in an scala.Option.
See also
flatMap
foreach
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that).
Equivalent to !(this eq that).
returns
true if the argument is not a reference to the receiver object; false otherwise.
Definition Classes
AnyRef
final def nonEmpty: Boolean
Returns false if the option is None, true otherwise.
Returns false if the option is None, true otherwise.
Definition Classes
Option
Note
Implemented here to avoid the implicit conversion to Iterable.
final def notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Definition Classes
AnyRef
Annotations
@native()
Note
not specified by SLS as a member of AnyRef
final def orElse[B >: Nothing](alternative: ⇒ Option[B]): Option[B]
Returns this scala.Option if it is nonempty, otherwise return the result of evaluating alternative.
Returns this scala.Option if it is nonempty, otherwise return the result of evaluating alternative.
alternative
the alternative expression.
Definition Classes
Option
Annotations
@inline()
final def orNull[A1 >: Nothing](implicit ev: <:<[Null, A1]): A1
Returns the option's value if it is nonempty, or null if it is empty.
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 scala.Option must often interface with code that expects and returns nulls.
Definition Classes
Option
Annotations
@inline()
Example:
1. val initialText: Option[String] = getInitialText val textField = new JComponent(initialText.orNull,20)
def productElementNames: Iterator[String]
An iterator over the names of all the elements of this product.
An iterator over the names of all the elements of this product.
Definition Classes
Product
final def synchronized[T0](arg0: ⇒ T0): T0
Definition Classes
AnyRef
final def toLeft[X](right: ⇒ X): Either[Nothing, X]
Returns a scala.util.Right containing the given argument right if this is empty, or a scala.util.Left containing this scala.Option's value if this scala.Option is nonempty.
Returns a scala.util.Right containing the given argument right if this is empty, or a scala.util.Left containing this scala.Option's value if this scala.Option is nonempty.
right
the expression to evaluate and return if this is empty
Definition Classes
Option
Annotations
@inline()
See also
toRight
def toList: List[Nothing]
Returns a singleton list containing the scala.Option's value if it is nonempty, or the empty list if the scala.Option is empty.
Returns a singleton list containing the scala.Option's value if it is nonempty, or the empty list if the scala.Option is empty.
Definition Classes
Option
final def toRight[X](left: ⇒ X): Either[X, Nothing]
Returns a scala.util.Left containing the given argument left if this scala.Option is empty, or a scala.util.Right containing this scala.Option's value if this is nonempty.
Returns a scala.util.Left containing the given argument left if this scala.Option is empty, or a scala.util.Right containing this scala.Option's value if this is nonempty.
left
the expression to evaluate and return if this is empty
Definition Classes
Option
Annotations
@inline()
See also
toLeft
final def wait(): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
@native() @throws(classOf[java.lang.InterruptedException])
final def withFilter(p: (Nothing) ⇒ Boolean): WithFilter
Necessary to keep scala.Option from being implicitly converted to scala.collection.Iterable in for comprehensions.
Necessary to keep scala.Option from being implicitly converted to scala.collection.Iterable in for comprehensions.
Definition Classes
Option
Annotations
@inline()
final def zip[A1 >: Nothing, B](that: Option[B]): Option[(A1, B)]
Returns a scala.Some formed from this option and another option by combining the corresponding elements in a pair.
Returns a scala.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.
that
the options which is going to be zipped
Definition Classes
Option
Example:
1. // Returns Option(("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")

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None

object None extends Option[Nothing] with Product with Serializable

Type Members

Value Members

Inherited from Option[Nothing]

Inherited from Serializable

Inherited from java.io.Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

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Packages

Package structure

Automatic imports

Guide

Common Imports

Specifying Durations

Using Futures For Non-blocking Computation

Avoid Blocking

None

object None extends Option[Nothing] with Product with Serializable

Type Members

Value Members

Inherited from Option[Nothing]

Inherited from Serializable

Inherited from java.io.Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

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None