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
// 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 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)
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Instance Constructors
Type Members
- class Val extends Value with 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
- protected
- Annotations
- @SerialVersionUID()
- abstract class Value extends Ordered[Value] with Serializable
The type of the enumerated values.
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.
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.
Test two objects for inequality.
- returns
trueif !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
- final def ##(): Int
Equivalent to
x.hashCodeexcept for boxed numeric types andnull.Equivalent to
x.hashCodeexcept for boxed numeric types andnull. 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. Fornullreturns a hashcode wherenull.hashCodethrows aNullPointerException.- 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 == thatis equivalent toif (x eq null) that eq null else x.equals(that).The expression
x == thatis equivalent toif (x eq null) that eq null else x.equals(that).- returns
trueif the receiver object is equivalent to the argument;falseotherwise.
- Definition Classes
- AnyRef → Any
- final def Value(i: Int, name: String): Value
Creates a fresh value, part of this enumeration, called
nameand identified by the integeri.Creates a fresh value, part of this enumeration, called
nameand identified by the integeri.- 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
iand namename.
- Attributes
- protected
- final 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.- 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.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.
Creates a fresh value, part of this enumeration.
- Attributes
- protected
- final def apply(x: Int): Value
The value of this enumeration with given id
x - 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 aClassCastExceptionat runtime, while the expressionList(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
ClassCastExceptionif the receiver object is not an instance of the erasure of typeT0.
- def clone(): AnyRef
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the
clonemethod is platform dependent.- returns
a copy of the receiver object.
- 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).Tests whether the argument (
that) is a reference to the receiver object (this).The
eqmethod implements an equivalence relation on non-null instances ofAnyRef, and has three additional properties:- It is consistent: for any non-null instances
xandyof typeAnyRef, multiple invocations ofx.eq(y)consistently returnstrueor consistently returnsfalse. - For any non-null instance
xof typeAnyRef,x.eq(null)andnull.eq(x)returnsfalse. null.eq(null)returnstrue.
When overriding the
equalsorhashCodemethods, 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
trueif the argument is a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
- def equals(arg0: AnyRef): Boolean
The equality method for reference types.
- 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
finalizemethod is invoked, as well as the interaction betweenfinalizeand 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
- def formatted(fmtstr: String): String
Returns string formatted according to given
formatstring.Returns string formatted according to given
formatstring. Format strings are as forString.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.
- def hashCode(): Int
The hashCode method for reference types.
- 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 returnfalse, while the expressionList(1).isInstanceOf[List[String]]will returntrue. 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
trueif the receiver object is an instance of erasure of typeT0;falseotherwise.
- Definition Classes
- Any
- final def maxId: Int
The one higher than the highest integer amongst those used to identify values in this enumeration.
- final def ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that).Equivalent to
!(this eq that).- returns
trueif the argument is not a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
- var nextId: Int
The integer to use to identify the next created value.
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.
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.
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
- def readResolve(): AnyRef
- Attributes
- protected
- final def synchronized[T0](arg0: => T0): T0
- Definition Classes
- AnyRef
- def toString(): String
The name of this enumeration.
The name of this enumeration.
- returns
a String representation of the object.
- Definition Classes
- Enumeration → AnyRef → Any
- def values: ValueSet
The values of this enumeration as a set.
- 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
- final def withName(s: String): Value
Return a
Valuefrom thisEnumerationwhose name matches the arguments.Return a
Valuefrom thisEnumerationwhose name matches the arguments. The names are determined automatically via reflection.- s
an
Enumerationname- returns
the
Valueof thisEnumerationif its name matchess
- Exceptions thrown
NoSuchElementExceptionif noValuewith a matching name is in thisEnumeration
- implicit object ValueOrdering extends Ordering[Value]
An ordering by id for values of this set
- object ValueSet extends SpecificIterableFactory[Value, ValueSet] with java.io.Serializable
A factory object for value sets
A factory object for value sets
- Annotations
- @SerialVersionUID()
Deprecated Value Members
- 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
- @deprecated
- Deprecated
(Since version 2.13.0) Use
->instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int,Float,ArrayorOptionwhich are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collectionand its sub-packages contain Scala's collections frameworkscala.collection.immutable- Immutable, sequential data-structures such asVector,List,Range,HashMaporHashSetscala.collection.mutable- Mutable, sequential data-structures such asArrayBuffer,StringBuilder,HashMaporHashSetscala.collection.concurrent- Mutable, concurrent data-structures such asTrieMapscala.concurrent- Primitives for concurrent programming such asFuturesandPromisesscala.io- Input and output operationsscala.math- Basic math functions and additional numeric types likeBigIntandBigDecimalscala.sys- Interaction with other processes and the operating systemscala.util.matching- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect- Scala's reflection API (scala-reflect.jar)scala.xml- XML parsing, manipulation, and serialization (scala-xml.jar)scala.collection.parallel- Parallel collections (scala-parallel-collections.jar)scala.util.parsing- Parser combinators (scala-parser-combinators.jar)scala.swing- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)Automatic imports
Identifiers in the scala package and the
scala.Predefobject are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
Listis an alias forscala.collection.immutable.List.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
Stringis an alias forjava.lang.String.