Enumeration

scala.Enumeration
abstract class Enumeration(initial: Int) 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.

Value parameters

initial

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

Attributes

Example

// 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

// Example of adding attributes to an enumeration by extending the Enumeration.Val class
object Planet extends Enumeration {
 protected case class PlanetVal(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): PlanetVal = x.asInstanceOf[PlanetVal]
 val G: Double = 6.67300E-11
 val Mercury = PlanetVal(3.303e+23, 2.4397e6)
 val Venus   = PlanetVal(4.869e+24, 6.0518e6)
 val Earth   = PlanetVal(5.976e+24, 6.37814e6)
 val Mars    = PlanetVal(6.421e+23, 3.3972e6)
 val Jupiter = PlanetVal(1.9e+27, 7.1492e7)
 val Saturn  = PlanetVal(5.688e+26, 6.0268e7)
 val Uranus  = PlanetVal(8.686e+25, 2.5559e7)
 val Neptune = PlanetVal(1.024e+26, 2.4746e7)
}
println(Planet.values.filter(_.radius > 7.0e6))
// output:
// Planet.ValueSet(Jupiter, Saturn, Uranus, Neptune)
Source
Enumeration.scala
Graph
Supertypes
trait Serializable
class Object
trait Matchable
class Any
Known subtypes
object RoundingMode.type
Self type

Members list

Type members

Classlikes

protected class Val(i: Int, name: String) extends Value, Serializable

A class implementing the scala.Enumeration.Value type.

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

Attributes

Source
Enumeration.scala
Supertypes
class Value
trait Serializable
trait Ordered[Value]
trait Comparable[Value]
class Object
trait Matchable
class Any
Show all
abstract class Value extends Ordered[Value], Serializable

The type of the enumerated values.

The type of the enumerated values.

Attributes

Source
Enumeration.scala
Supertypes
trait Serializable
trait Ordered[Value]
trait Comparable[Value]
class Object
trait Matchable
class Any
Show all
Known subtypes
class Val
object ValueOrdering extends Ordering[Value]

An ordering by id for values of this set

An ordering by id for values of this set

Attributes

Source
Enumeration.scala
Supertypes
trait Ordering[Value]
trait Equiv[Value]
trait Serializable
trait Comparator[Value]
class Object
trait Matchable
class Any
Show all
Self type

A class for sets of values.

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

Value parameters

nnIds

The set of ids of values (adjusted so that the lowest value does not fall below zero), organized as a BitSet.

Attributes

Companion
object
Source
Enumeration.scala
Supertypes

A factory object for value sets

A factory object for value sets

Attributes

Companion
class
Source
Enumeration.scala
Supertypes
Self type
ValueSet.type

Value members

Constructors

def this()

Attributes

Source
Enumeration.scala

Concrete methods

final protected def Value: Value

Creates a fresh value, part of this enumeration.

Creates a fresh value, part of this enumeration.

Attributes

Source
Enumeration.scala
final protected def Value(i: Int): Value

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

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

Value parameters

i

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

Attributes

Returns

Fresh value identified by i.

Source
Enumeration.scala
final protected def Value(name: String): Value

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

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

Value parameters

name

A human-readable name for that value.

Attributes

Returns

Fresh value called name.

Source
Enumeration.scala
final protected def Value(i: Int, name: String): Value

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

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

Value parameters

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.

Attributes

Returns

Fresh value with the provided identifier i and name name.

Source
Enumeration.scala
final def apply(x: Int): Value

The value of this enumeration with given id x

The value of this enumeration with given id x

Attributes

Source
Enumeration.scala
final def maxId: Int

The one higher than the highest integer amongst those used to identify values in this enumeration.

The one higher than the highest integer amongst those used to identify values in this enumeration.

Attributes

Source
Enumeration.scala
protected def readResolve(): AnyRef

Attributes

Source
Enumeration.scala
override def toString: String

The name of this enumeration.

The name of this enumeration.

Attributes

Definition Classes
Any
Source
Enumeration.scala

The values of this enumeration as a set.

The values of this enumeration as a set.

Attributes

Source
Enumeration.scala
final def withName(s: String): Value

Return a Value from this Enumeration whose name matches the argument s.

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

Value parameters

s

an Enumeration name

Attributes

Returns

the Value of this Enumeration if its name matches s

Throws

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

Source
Enumeration.scala

Concrete fields

protected var nextId: Int

The integer to use to identify the next created value.

The integer to use to identify the next created value.

Attributes

Source
Enumeration.scala
protected var nextName: Iterator[String]

The string to use to name the next created value.

The string to use to name the next created value.

Attributes

Source
Enumeration.scala