scala

Option

class Option[+A] extends Product

This class represents optional values. Instances of Option are either instances of case class Some or it is case object None.

attributes: sealed abstract
known subclasses: Some, None
Go to: companion

Inherits

  1. Product
  2. Equals
  3. AnyRef
  4. Any

Value Members

  1. def canEqual(that: Any): Boolean

    A method that should be called from every well-designed equals method that is open to be overridden in a subclass

    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.

    attributes: abstract
    definition classes: Equals
    Go to: companion
  2. def equals(arg0: Any): Boolean

    This method is used to compare the receiver object (this) with the argument object (arg0) for equivalence

    This method is used to compare the receiver object (this) with the argument object (arg0) for equivalence.

    The default implementations of this method is an equivalence relation:

    • It is reflexive: for any instance x of type Any, x.equals(x) should return true.
    • It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true.
    • It is transitive: for any instances x, y, and z of type AnyRef if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.

    If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is often necessary to override hashCode to ensure that objects that are "equal" (o1.equals(o2) returns true) hash to the same Int (o1.hashCode.equals(o2.hashCode)).

    arg0

    the object to compare against this object for equality.

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    definition classes: AnyRef ⇐ Any
    Go to: companion
  3. def exists(p: (A) ⇒ Boolean): Boolean

    If the option is nonempty, p(value), otherwise false

    If the option is nonempty, p(value), otherwise false.

    p

    the predicate to test

    Go to: companion
  4. def filter(p: (A) ⇒ Boolean): Option[A]

    If the option is nonempty and the given predicate p yields false on its value, return None

    If the option is nonempty and the given predicate p yields false on its value, return None. Otherwise return the option value itself.

    p

    the predicate used for testing.

    Go to: companion
  5. def flatMap[B](f: (A) ⇒ Option[B]): Option[B]

    If the option is nonempty, return a function applied to its value

    If the option is nonempty, return a function applied to its value. Otherwise return None.

    f

    the function to apply

    Go to: companion
  6. def foreach[U](f: (A) ⇒ 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. Do nothing if it is empty.

    f

    the procedure to apply.

    Go to: companion
  7. def get: A

    get the value of this option

    get the value of this option.

    attributes: abstract
    Go to: companion
  8. def getOrElse[B >: A](default: ⇒ B): B

    If the option is nonempty return its value, otherwise return the result of evaluating a default expression

    If the option is nonempty return its value, otherwise return the result of evaluating a default expression.

    default

    the default expression.

    Go to: companion
  9. def hashCode(): Int

    Returns a hash code value for the object

    Returns a hash code value for the object.

    The default hashing algorithm is platform dependent.

    Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

    definition classes: AnyRef ⇐ Any
    Go to: companion
  10. def isDefined: Boolean

    True if the option is a Some(

    True if the option is a Some(...) false otherwise.

    Go to: companion
  11. def isEmpty: Boolean

    True if the option is the None value, false otherwise

    True if the option is the None value, false otherwise.

    attributes: abstract
    Go to: companion
  12. def iterator: Iterator[A]

    An singleton iterator returning the option's value if it is nonempty or the empty iterator if the option is empty

    An singleton iterator returning the option's value if it is nonempty or the empty iterator if the option is empty.

    Go to: companion
  13. def map[B](f: (A) ⇒ B): Option[B]

    If the option is nonempty, return a function applied to its value, wrapped in a Some i

    If the option is nonempty, return a function applied to its value, wrapped in a Some i.e. Some(f(this.get)). Otherwise return None.

    f

    the function to apply

    Go to: companion
  14. def orElse[B >: A](alternative: ⇒ Option[B]): Option[B]

    If the option is nonempty return it, otherwise return the result of evaluating an alternative expression

    If the option is nonempty return it, otherwise return the result of evaluating an alternative expression.

    alternative

    the alternative expression.

    Go to: companion
  15. def orNull[A1 >: A](ev: <:<[Null, A1]): A1

    The option's value if it is nonempty, or null if it is empty

    The option's value if it is nonempty, or null if it is empty. The use of null of course is discouraged, but code written to use Options often must interface with code which expects and returns nulls.

    Go to: companion
  16. def partialMap[B](pf: PartialFunction[A, B]): Option[B]

    If the given partial function pf is defined for the option's value, apply it to the value

    If the given partial function pf is defined for the option's value, apply it to the value. Otherwise, None.

    pf

    the partial function.

    Go to: companion
  17. def productArity: Int

    return k for a product A(x_1,

    return k for a product A(x_1,...,x_k)

    attributes: abstract
    definition classes: Product
    Go to: companion
  18. def productElement(n: Int): Any

    for a product A(x_1,

    for a product A(x_1,...,x_k), returns x_(n+1) for 0 <= n < k

    n

    the index of the element to return

    returns

    The element n elements after the first element

    attributes: abstract
    definition classes: Product
    Go to: companion
  19. def productElements: Iterator[Any]

  20. def productIterator: Iterator[Any]

    An iterator that returns all fields of this product

    An iterator that returns all fields of this product

    definition classes: Product
    Go to: companion
  21. def productPrefix: String

    By default the empty string

    By default the empty string. Implementations may override this method in order to prepend a string prefix to the result of the toString methods.

    definition classes: Product
    Go to: companion
  22. def toLeft[X](right: ⇒ X): Product with Either[A, X]

    An Either that is a Right with the given argument right if this is empty, or a Left if this is nonempty with the option's value

    An Either that is a Right with the given argument right if this is empty, or a Left if this is nonempty with the option's value.

    Go to: companion
  23. def toList: List[A]

    A singleton list containing the option's value if it is nonempty or the empty list if the option is empty

    A singleton list containing the option's value if it is nonempty or the empty list if the option is empty.

    Go to: companion
  24. def toRight[X](left: ⇒ X): Product with Either[X, A]

    An Either that is a Left with the given argument left if this is empty, or a Right if this is nonempty with the option's value

    An Either that is a Left with the given argument left if this is empty, or a Right if this is nonempty with the option's value.

    Go to: companion
  25. def toString(): String

    Returns a string representation of the object

    Returns a string representation of the object.

    The default representation is platform dependent.

    definition classes: AnyRef ⇐ Any
    Go to: companion

Instance constructors

  1. new Option()