Class scala.Enumeration

abstract class Enumeration extends Serializable

Defines a finite set of values specific to the enumeration. Typically these values enumerate all possible forms something can take and provide a lightweight alternative to case classes.

Each call to a Value method adds a new unique value to the enumeration. To be accessible, these values are usually defined as val members of the enumeration.

All values in an enumeration share a common, unique type defined as the Value type member of the enumeration (Value selected on the stable identifier path of the enumeration instance).

Values SHOULD NOT be added to an enumeration after its construction; doing so makes the enumeration thread-unsafe. If values are added to an enumeration from multiple threads (in a non-synchronized fashion) after construction, the behavior of the enumeration is undefined.

Self Type
Enumeration
Annotations
@SerialVersionUID()
Source
Enumeration.scala
Examples:
  1. // Define a new enumeration with a type alias and work with the full set of enumerated values
    object WeekDay extends Enumeration {
      type WeekDay = Value
      val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value
    }
    import WeekDay._
    
    def isWorkingDay(d: WeekDay) = ! (d == Sat || d == Sun)
    
    WeekDay.values filter isWorkingDay foreach println
    // output:
    // Mon
    // Tue
    // Wed
    // Thu
    // Fri
  2. ,
  3. // Example of adding attributes to an enumeration by extending the Enumeration.Val class
    object Planet extends Enumeration {
      protected case class Val(mass: Double, radius: Double) extends super.Val {
        def surfaceGravity: Double = Planet.G * mass / (radius * radius)
        def surfaceWeight(otherMass: Double): Double = otherMass * surfaceGravity
      }
      import scala.language.implicitConversions
      implicit def valueToPlanetVal(x: Value): Val = x.asInstanceOf[Val]
    
      val G: Double = 6.67300E-11
      val Mercury = Val(3.303e+23, 2.4397e6)
      val Venus   = Val(4.869e+24, 6.0518e6)
      val Earth   = Val(5.976e+24, 6.37814e6)
      val Mars    = Val(6.421e+23, 3.3972e6)
      val Jupiter = Val(1.9e+27, 7.1492e7)
      val Saturn  = Val(5.688e+26, 6.0268e7)
      val Uranus  = Val(8.686e+25, 2.5559e7)
      val Neptune = Val(1.024e+26, 2.4746e7)
    }
    
    println(Planet.values.filter(_.radius > 7.0e6))
    // output:
    // Planet.ValueSet(Jupiter, Saturn, Uranus, Neptune)
Linear Supertypes
java.io.Serializable, AnyRef, Any
Known Subclasses
RoundingMode

Instance Constructors

new Enumeration()

new Enumeration(initial: Int)

initial

The initial value from which to count the integers that identifies values at run-time.

Type Members

class Val extends Value with Serializable

A class implementing the scala.Enumeration.Value type. This class can be overridden to change the enumeration's naming and integer identification behaviour.

Attributes
protected
Annotations
@SerialVersionUID()

abstract class Value extends Ordered[Value] with Serializable

The type of the enumerated values.

Annotations
@SerialVersionUID()

class ValueSet extends AbstractSet[Value] with SortedSet[Value] with SortedSetOps[Value, SortedSet, ValueSet] with StrictOptimizedIterableOps[Value, Set, ValueSet] with Serializable

A class for sets of values. Iterating through this set will yield values in increasing order of their ids.

Value Members

final def !=(arg0: Any): Boolean

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. 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

def +(other: String): String

Implicit
This member is added by an implicit conversion from Enumeration toany2stringadd[Enumeration] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd

def ->[B](y: B): (Enumeration, B)

Implicit
This member is added by an implicit conversion from Enumeration toArrowAssoc[Enumeration] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()

final def ==(arg0: Any): Boolean

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 Value(i: Int, name: String): Value

Creates a fresh value, part of this enumeration, called name and identified by the integer i.

i

An integer that identifies this value at run-time. It must be unique amongst all values of the enumeration.

name

A human-readable name for that value.

returns

Fresh value with the provided identifier i and name name.

Attributes
protected

final def Value(name: String): Value

Creates a fresh value, part of this enumeration, called name.

name

A human-readable name for that value.

returns

Fresh value called name.

Attributes
protected

final def Value(i: Int): Value

Creates a fresh value, part of this enumeration, identified by the integer i.

i

An integer that identifies this value at run-time. It must be unique amongst all values of the enumeration.

returns

Fresh value identified by i.

Attributes
protected

final def Value: Value

Creates a fresh value, part of this enumeration.

Attributes
protected

final def apply(x: Int): Value

final def asInstanceOf[T0]: 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.

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
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
Note

not specified by SLS as a member of AnyRef

def ensuring(cond: (Enumeration) => Boolean, msg: => Any): Enumeration

Implicit
This member is added by an implicit conversion from Enumeration toEnsuring[Enumeration] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: (Enumeration) => Boolean): Enumeration

Implicit
This member is added by an implicit conversion from Enumeration toEnsuring[Enumeration] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean, msg: => Any): Enumeration

Implicit
This member is added by an implicit conversion from Enumeration toEnsuring[Enumeration] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

def ensuring(cond: Boolean): Enumeration

Implicit
This member is added by an implicit conversion from Enumeration toEnsuring[Enumeration] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring

final def eq(arg0: AnyRef): Boolean

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: AnyRef): Boolean

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

def finalize(): Unit

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

def formatted(fmtstr: String): String

Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

Implicit
This member is added by an implicit conversion from Enumeration toStringFormat[Enumeration] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()

final def getClass(): Class[_ <: AnyRef]

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()

def hashCode(): Int

The hashCode method for reference types. See hashCode in scala.Any.

returns

the hash code value for this object.

Definition Classes
AnyRef → Any
Annotations
@native()

final def isInstanceOf[T0]: Boolean

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

final def maxId: Int

final def ne(arg0: AnyRef): Boolean

Equivalent to !(this eq that).

returns

true if the argument is not a reference to the receiver object; false otherwise.

Definition Classes
AnyRef

var nextId: Int

The integer to use to identify the next created value.

Attributes
protected

var nextName: Iterator[String]

The string to use to name the next created value.

Attributes
protected

final def notify(): Unit

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.

Definition Classes
AnyRef
Annotations
@native()
Note

not specified by SLS as a member of AnyRef

def readResolve(): AnyRef

Attributes
protected

final def synchronized[T0](arg0: => T0): T0

Definition Classes
AnyRef

def toString(): String

The name of this enumeration.

returns

a String representation of the object.

Definition Classes
Enumeration → AnyRef → Any

def values: ValueSet

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
@throws(classOf[java.lang.InterruptedException]) @native()

final def withName(s: String): Value

Return a Value from this Enumeration whose name matches the argument s. The names are determined automatically via reflection.

s

an Enumeration name

returns

the Value of this Enumeration if its name matches s

Exceptions thrown

NoSuchElementException if no Value with a matching name is in this Enumeration

implicit object ValueOrdering extends Ordering[Value]

object ValueSet extends SpecificIterableFactory[Value, ValueSet] with java.io.Serializable

A factory object for value sets

Annotations
@SerialVersionUID()

© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala/Enumeration.html