Scala Standard Library2.13.15 < Back


# Packages

-  package root

  This is the documentation for the Scala standard library.

  This is the documentation for the Scala standard library.

  #### Package structure

  The scala package contains core types like `Int`, `Float`, `Array` or `Option` which are accessible in all Scala compilation units without explicit qualification or imports.

  Notable packages include:

  - `scala.collection` and its sub-packages contain Scala's collections framework
    - `scala.collection.immutable` - Immutable, sequential data-structures such as `Vector`, `List`, `Range`, `HashMap` or `HashSet`
    - `scala.collection.mutable` - Mutable, sequential data-structures such as `ArrayBuffer`, `StringBuilder`, `HashMap` or `HashSet`
    - `scala.collection.concurrent` - Mutable, concurrent data-structures such as `TrieMap`
  - `scala.concurrent` - Primitives for concurrent programming such as `Futures` and `Promises`
  - `scala.io` - Input and output operations
  - `scala.math` - Basic math functions and additional numeric types like `BigInt` and `BigDecimal`
  - `scala.sys` - Interaction with other processes and the operating system
  - `scala.util.matching` - Regular expressions

  Other 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.Predef` object are always in scope by default.

  Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example, `List` is an alias for `scala.collection.immutable.List`.

  Other aliases refer to classes provided by the underlying platform. For example, on the JVM, `String` is an alias for `java.lang.String`.

  Definition Classes
    root
-  package scala

  Core Scala types.

  Core Scala types. They are always available without an explicit import.

  Definition Classes
    root
-  abstract class Enumeration extends Serializable

  Defines a finite set of values specific to the enumeration.

  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.

  Definition Classes
    scala
  Annotations
    @SerialVersionUID()
  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.     // 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)

- Val
- Value
- ValueOrdering
- ValueSet

c

scala.Enumeration

# Val

###

#### 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()
Source
  Enumeration.scala

Linear Supertypes
Value, java.io.Serializable, math.Ordered[Value], Comparable[Value], AnyRef, Any
Type Hierarchy

Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. Val
2. Value
3. Serializable
4. Ordered
5. Comparable
6. AnyRef
7. Any

Implicitly

1. by orderingToOrdered
2. by any2stringadd
3. by StringFormat
4. by Ensuring
5. by ArrowAssoc

1. Hide All
2. Show All

Visibility

1. Public
2. Protected

### Instance Constructors

1.  new Val()
2.  new Val(name: String)
3.  new Val(i: Int)
4.  new Val(i: Int, name: String)

### 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.  def +(v: Value): ValueSet

   Create a ValueSet which contains this value and another one

   Create a ValueSet which contains this value and another one

   Definition Classes
     Value
4.  def ->[B](y: B): (Val, B)
   Implicit
     This member is added by an implicit conversion from Val toArrowAssoc[Val] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
5.  def <(that: Value): Boolean

   Returns true if `this` is less than `that`

   Returns true if `this` is less than `that`

   Definition Classes
     Ordered
6.  def <=(that: Value): Boolean

   Returns true if `this` is less than or equal to `that`.

   Returns true if `this` is less than or equal to `that`.

   Definition Classes
     Ordered
7.  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
8.  def >(that: Value): Boolean

   Returns true if `this` is greater than `that`.

   Returns true if `this` is greater than `that`.

   Definition Classes
     Ordered
9.  def >=(that: Value): Boolean

   Returns true if `this` is greater than or equal to `that`.

   Returns true if `this` is greater than or equal to `that`.

   Definition Classes
     Ordered
10.  final def asInstanceOf[T0]: T0

    Forces the compiler to treat the receiver object as having type `T0`, even though doing so may violate type safety.

    Forces the compiler to treat the receiver object as having type `T0`, even though doing so may violate type safety.

    This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.

    It is platform dependent whether `asInstanceOf` has any effect at runtime. It might do a runtime type test on the erasure of `T0`, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.

    In particular, `asInstanceOf` is not a type test. It does **not** mean:

        this match {
         case x: T0 => x
         case _     => throw ClassCastException("...")

    Use pattern matching or isInstanceOf for type testing instead.

    Situations where `asInstanceOf` is useful:

    - when flow analysis fails to deduce `T0` automatically
    - when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.

    Be careful of using `asInstanceOf` when `T0` is a primitive type. When `T0` is primitive, `asInstanceOf` may insert a conversion instead of a type test. If your intent is to convert, use a `toT` method (`x.toChar`, `x.toByte`, etc.).

    returns

      the receiver object.

    Definition Classes
      Any
    Exceptions thrown

      `ClassCastException` if the receiver is not an instance of the erasure of `T0`, if that can be checked on this platform

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

      not specified by SLS as a member of AnyRef

12.  def compare(that: Value): Int

    Result of comparing `this` with operand `that`.

    Result of comparing `this` with operand `that`.

    Implement this method to determine how instances of A will be sorted.

    Returns `x` where:

    - `x < 0` when `this < that`
    - `x == 0` when `this == that`
    - `x > 0` when `this > that`
    Definition Classes
      Value → Ordered
13.  def compareTo(that: Value): Int

    Result of comparing `this` with operand `that`.

    Result of comparing `this` with operand `that`.

    Definition Classes
      Ordered → Comparable
14.  def ensuring(cond: (Val) => Boolean, msg: => Any): Val
    Implicit
      This member is added by an implicit conversion from Val toEnsuring[Val] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
15.  def ensuring(cond: (Val) => Boolean): Val
    Implicit
      This member is added by an implicit conversion from Val toEnsuring[Val] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
16.  def ensuring(cond: Boolean, msg: => Any): Val
    Implicit
      This member is added by an implicit conversion from Val toEnsuring[Val] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
17.  def ensuring(cond: Boolean): Val
    Implicit
      This member is added by an implicit conversion from Val toEnsuring[Val] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
18.  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
19.  def equals(other: 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
      Value → AnyRef → Any
20.  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

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

    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()
22.  def hashCode(): Int

    The hashCode method for reference types.

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

    returns

      the hash code value for this object.

    Definition Classes
      Value → AnyRef → Any
23.  def id: Int

    the id and bit location of this enumeration value

    the id and bit location of this enumeration value

    Definition Classes
      Val → Value
24.  final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object has the same erasure as `T0`.

    Test whether the dynamic type of the receiver object has the same erasure as `T0`.

    Depending on what `T0` is, the test is done in one of the below ways:

    - `T0` is a non-parameterized class type, e.g. `BigDecimal`: this method returns `true` if the value of the receiver object is a `BigDecimal` or a subtype of `BigDecimal`.
    - `T0` is a parameterized class type, e.g. `List[Int]`: this method returns `true` if the value of the receiver object is some `List[X]` for any `X`. For example, `List(1, 2, 3).isInstanceOf[List[String]]` will return true.
    - `T0` is some singleton type `x.type` or literal `x`: this method returns `this.eq(x)`. For example, `x.isInstanceOf[1]` is equivalent to `x.eq(1)`
    - `T0` is an intersection `X with Y` or `X & Y: this method is equivalent to` x.isInstanceOf[X] && x.isInstanceOf[Y]``
    - `T0` is a union `X | Y`: this method is equivalent to `x.isInstanceOf[X] || x.isInstanceOf[Y]`
    - `T0` is a type parameter or an abstract type member: this method is equivalent to `isInstanceOf[U]` where `U` is `T0`'s upper bound, `Any` if `T0` is unbounded. For example, `x.isInstanceOf[A]` where `A` is an unbounded type parameter will return true for any value of `x`.

    This is exactly equivalent to the type pattern `_: T0`

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any
    Note

      due to the unexpectedness of `List(1, 2, 3).isInstanceOf[List[String]]` returning true and `x.isInstanceOf[A]` where `A` is a type parameter or abstract member returning true, these forms issue a warning.

25.  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
26.  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

27.  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

28.  def readResolve(): AnyRef
    Attributes
      protected
29.  final def synchronized[T0](arg0: => T0): T0

    Executes the code in `body` with an exclusive lock on `this`.

    Executes the code in `body` with an exclusive lock on `this`.

    returns

      the result of `body`

    Definition Classes
      AnyRef
30.  def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

      a String representation of the object.

    Definition Classes
      Val → AnyRef → Any
31.  final def wait(): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
    Note

      not specified by SLS as a member of AnyRef

32.  final def wait(arg0: Long, arg1: Int): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
    Note

      not specified by SLS as a member of AnyRef

33.  final def wait(arg0: Long): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException]) @native()
    Note

      not specified by SLS as a member of AnyRef

### Shadowed Implicit Value Members

1.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from Val toany2stringadd[Val] performed by method any2stringadd in scala.Predef.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (val: any2stringadd[Val]).+(other)

   Definition Classes
     any2stringadd
2.  def <(that: Val): Boolean

   Returns true if `this` is less than `that`

   Returns true if `this` is less than `that`

   Implicit
     This member is added by an implicit conversion from Val tomath.Ordered[Val] performed by method orderingToOrdered in scala.math.Ordered.This conversion will take place only if an implicit value of type math.Ordering[Val] is in scope.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (val: math.Ordered[Val]).<(that)

   Definition Classes
     Ordered
3.  def <=(that: Val): Boolean

   Returns true if `this` is less than or equal to `that`.

   Returns true if `this` is less than or equal to `that`.

   Implicit
     This member is added by an implicit conversion from Val tomath.Ordered[Val] performed by method orderingToOrdered in scala.math.Ordered.This conversion will take place only if an implicit value of type math.Ordering[Val] is in scope.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (val: math.Ordered[Val]).<=(that)

   Definition Classes
     Ordered
4.  def >(that: Val): Boolean

   Returns true if `this` is greater than `that`.

   Returns true if `this` is greater than `that`.

   Implicit
     This member is added by an implicit conversion from Val tomath.Ordered[Val] performed by method orderingToOrdered in scala.math.Ordered.This conversion will take place only if an implicit value of type math.Ordering[Val] is in scope.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (val: math.Ordered[Val]).>(that)

   Definition Classes
     Ordered
5.  def >=(that: Val): Boolean

   Returns true if `this` is greater than or equal to `that`.

   Returns true if `this` is greater than or equal to `that`.

   Implicit
     This member is added by an implicit conversion from Val tomath.Ordered[Val] performed by method orderingToOrdered in scala.math.Ordered.This conversion will take place only if an implicit value of type math.Ordering[Val] is in scope.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (val: math.Ordered[Val]).>=(that)

   Definition Classes
     Ordered
6.  def compare(that: Val): Int

   Result of comparing `this` with operand `that`.

   Result of comparing `this` with operand `that`.

   Implement this method to determine how instances of A will be sorted.

   Returns `x` where:

   - `x < 0` when `this < that`
   - `x == 0` when `this == that`
   - `x > 0` when `this > that`
   Implicit
     This member is added by an implicit conversion from Val tomath.Ordered[Val] performed by method orderingToOrdered in scala.math.Ordered.This conversion will take place only if an implicit value of type math.Ordering[Val] is in scope.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (val: math.Ordered[Val]).compare(that)

   Definition Classes
     Ordered
7.  def compareTo(that: Val): Int

   Result of comparing `this` with operand `that`.

   Result of comparing `this` with operand `that`.

   Implicit
     This member is added by an implicit conversion from Val tomath.Ordered[Val] performed by method orderingToOrdered in scala.math.Ordered.This conversion will take place only if an implicit value of type math.Ordering[Val] is in scope.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (val: math.Ordered[Val]).compareTo(that)

   Definition Classes
     Ordered → Comparable

### Deprecated Value Members

1.  def formatted(fmtstr: String): String

   Returns string formatted according to given `format` 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 Val toStringFormat[Val] performed by method StringFormat in scala.Predef.
   Definition Classes
     StringFormat
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.

2.  def →[B](y: B): (Val, B)
   Implicit
     This member is added by an implicit conversion from Val toArrowAssoc[Val] 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.

### Inherited from Value

### Inherited from java.io.Serializable

### Inherited from math.Ordered[Value]

### Inherited from Comparable[Value]

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion orderingToOrdered fromVal to math.Ordered[Val]

### Inherited by implicit conversion any2stringadd fromVal to any2stringadd[Val]

### Inherited by implicit conversion StringFormat fromVal to StringFormat[Val]

### Inherited by implicit conversion Ensuring fromVal to Ensuring[Val]

### Inherited by implicit conversion ArrowAssoc fromVal to ArrowAssoc[Val]

### Ungrouped