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scala

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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  1. None
  2. Option
  3. Serializable
  4. Serializable
  5. Product
  6. Equals
  7. AnyRef
  8. Any
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Visibility
  1. Public
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Type Members

  1. 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

  1. 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
  2. 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
  3. 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
  4. 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.

  5. 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[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
    Note

    not specified by SLS as a member of AnyRef

  6. 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}
  7. 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.

    This is equivalent to:

    option match {
      case Some(x) => x == elem
      case None    => false
    }
    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"
  8. 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
  9. 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
  10. 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.

    This is equivalent to:

    option match {
      case Some(x) => p(x)
      case None    => false
    }
    p

    the predicate to test

    Definition Classes
    Option
    Annotations
    @inline()
  11. 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.

    This is equivalent to:

    option match {
      case Some(x) if p(x) => Some(x)
      case _               => None
    }
    p

    the predicate used for testing.

    Definition Classes
    Option
    Annotations
    @inline()
  12. 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.

    This is equivalent to:

    option match {
      case Some(x) if !p(x) => Some(x)
      case _                => None
    }
    p

    the predicate used for testing.

    Definition Classes
    Option
    Annotations
    @inline()
  13. 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[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
    Note

    not specified by SLS as a member of AnyRef

  14. 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).

    This is equivalent to:

    option match {
      case Some(x) => f(x)
      case None    => None
    }
    f

    the function to apply

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    map

    foreach

  15. def flatten[B](implicit ev: <:<[Nothing, Option[B]]): Option[B]
    Definition Classes
    Option
  16. 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.

    This is equivalent to:

    option match {
      case Some(x) => f(x)
      case None    => ifEmpty
    }

    This is also equivalent to:

    option map f getOrElse ifEmpty
    ifEmpty

    the expression to evaluate if empty.

    f

    the function to apply if nonempty.

    Definition Classes
    Option
    Annotations
    @inline()
  17. 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.

    This is equivalent to:

    option match {
      case Some(x) => p(x)
      case None    => true
    }
    p

    the predicate to test

    Definition Classes
    Option
    Annotations
    @inline()
  18. 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.

    This is equivalent to:

    option match {
      case Some(x) => f(x)
      case None    => ()
    }
    f

    the procedure to apply.

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    map

    flatMap

  19. def get: Nothing

    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
    }
    Definition Classes
    NoneOption
    Exceptions thrown

    java.util.NoSuchElementException if the option is empty.

    Note

    The option must be nonempty.

  20. 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()
  21. 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.

    This is equivalent to:

    option match {
      case Some(x) => x
      case None    => default
    }
    default

    the default expression.

    Definition Classes
    Option
    Annotations
    @inline()
  22. 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.

    This is equivalent to:

    option match {
      case Some(_) => true
      case None    => false
    }
    Definition Classes
    Option
  23. def isEmpty: Boolean

    Returns true if the option is None, false otherwise.

    Returns true if the option is None, false otherwise.

    This is equivalent to:

    option match {
      case Some(_) => false
      case None    => true
    }
    Definition Classes
    NoneOption
  24. 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
  25. 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
  26. 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.

    This is equivalent to:

    option match {
      case Some(x) => Some(f(x))
      case None    => 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

  27. 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
  28. final def nonEmpty: Boolean

    Returns false if the option is None, true otherwise.

    Returns false if the option is None, true otherwise.

    This is equivalent to:

    option match {
      case Some(_) => true
      case None    => false
    }
    Definition Classes
    Option
    Note

    Implemented here to avoid the implicit conversion to Iterable.

  29. 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

  30. 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

  31. 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.

    This is equivalent to:

    option match {
      case Some(x) => Some(x)
      case None    => alternative
    }
    alternative

    the alternative expression.

    Definition Classes
    Option
    Annotations
    @inline()
  32. 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.

    This is equivalent to:

    option match {
      case Some(x) => x
      case None    => null
    }
    Definition Classes
    Option
    Annotations
    @inline()
    Example:
    1. val initialText: Option[String] = getInitialText
      val textField = new JComponent(initialText.orNull,20)
  33. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  34. 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.

    This is equivalent to:

    option match {
      case Some(x) => Left(x)
      case None    => Right(right)
    }
    right

    the expression to evaluate and return if this is empty

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    toRight

  35. 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.

    This is equivalent to:

    option match {
      case Some(x) => List(x)
      case None    => Nil
    }
    Definition Classes
    Option
  36. 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.

    This is equivalent to:

    option match {
      case Some(x) => Right(x)
      case None    => Left(left)
    }
    left

    the expression to evaluate and return if this is empty

    Definition Classes
    Option
    Annotations
    @inline()
    See also

    toLeft

  37. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  38. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  39. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  40. 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()

Inherited from Option[Nothing]

Inherited from Serializable

Inherited from java.io.Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

Ungrouped