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:

    Other packages exist. See the complete list on the right.

    Additional parts of the standard library are shipped as separate libraries. These include:

    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. , 

    2. // 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)
  • Val
  • Value
  • ValueOrdering
  • ValueSet
o

scala.Enumeration

ValueOrdering

implicit object ValueOrdering extends Ordering[Value]

An ordering by id for values of this set

Source
Enumeration.scala
Linear Supertypes
math.Ordering[Value], math.PartialOrdering[Value], math.Equiv[Value], java.io.Serializable, Comparator[Value], AnyRef, Any
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. ValueOrdering
  2. Ordering
  3. PartialOrdering
  4. Equiv
  5. Serializable
  6. Comparator
  7. AnyRef
  8. Any
  1. Hide All
  2. Show All
Visibility
  1. Public
  2. Protected

Type Members

  1. class OrderingOps extends AnyRef

    This inner class defines comparison operators available for T.

    This inner class defines comparison operators available for T.

    Definition Classes
    Ordering

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. 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
  4. 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 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.

  5. 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

  6. def compare(x: Value, y: Value): Int

    Returns an integer whose sign communicates how x compares to y.

    Returns an integer whose sign communicates how x compares to y.

    The result sign has the following meaning:

    • negative if x < y
    • positive if x > y
    • zero otherwise (if x == y)
    Definition Classes
    ValueOrdering → Ordering → Comparator
  7. 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
  8. def equals(arg0: AnyRef): 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
    AnyRef → Any
  9. def equiv(x: Value, y: Value): Boolean

    Return true if x == y in the ordering.

    Return true if x == y in the ordering.

    Definition Classes
    Ordering → PartialOrdering → Equiv
  10. 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

  11. 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()
  12. def gt(x: Value, y: Value): Boolean

    Return true if x > y in the ordering.

    Return true if x > y in the ordering.

    Definition Classes
    Ordering → PartialOrdering
  13. def gteq(x: Value, y: Value): Boolean

    Return true if x >= y in the ordering.

    Return true if x >= y in the ordering.

    Definition Classes
    Ordering → PartialOrdering
  14. 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
    AnyRef → Any
    Annotations
    @native()
  15. 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 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
  16. def isReverseOf(other: math.Ordering[_]): Boolean

    Returns whether or not the other ordering is the opposite ordering of this one.

    Returns whether or not the other ordering is the opposite ordering of this one.

    Equivalent to other == this.reverse.

    Implementations should only override this method if they are overriding reverse as well.

    Definition Classes
    Ordering
  17. def lt(x: Value, y: Value): Boolean

    Return true if x < y in the ordering.

    Return true if x < y in the ordering.

    Definition Classes
    Ordering → PartialOrdering
  18. def lteq(x: Value, y: Value): Boolean

    Return true if x <= y in the ordering.

    Return true if x <= y in the ordering.

    Definition Classes
    Ordering → PartialOrdering
  19. def max[U <: Value](x: U, y: U): U

    Return x if x >= y, otherwise y.

    Return x if x >= y, otherwise y.

    Definition Classes
    Ordering
  20. def min[U <: Value](x: U, y: U): U

    Return x if x <= y, otherwise y.

    Return x if x <= y, otherwise y.

    Definition Classes
    Ordering
  21. implicit def mkOrderingOps(lhs: Value): OrderingOps

    This implicit method augments T with the comparison operators defined in scala.math.Ordering.Ops.

    This implicit method augments T with the comparison operators defined in scala.math.Ordering.Ops.

    Definition Classes
    Ordering
  22. 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
  23. 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

  24. 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

  25. def on[U](f: (U) => Value): math.Ordering[U]

    Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

    Given f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:

    def compare(x:U, y:U) = Ordering[T].compare(f(x), f(y))
    Definition Classes
    Ordering
  26. def orElse(other: math.Ordering[Value]): math.Ordering[Value]

    Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result of others compare function.

    Creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result of others compare function.

    other

    an Ordering to use if this Ordering returns zero

    Definition Classes
    Ordering
    Example:

    1. case class Pair(a: Int, b: Int)

val pairOrdering = Ordering.by[Pair, Int](_.a)
                           .orElse(Ordering.by[Pair, Int](_.b))
  27. def orElseBy[S](f: (Value) => S)(implicit ord: math.Ordering[S]): math.Ordering[Value]

    Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

    Given f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:

    Ordering[S].compare(f(x), f(y))

    This function is equivalent to passing the result of Ordering.by(f) to orElse.

    Definition Classes
    Ordering
    Example:

    1. case class Pair(a: Int, b: Int)

val pairOrdering = Ordering.by[Pair, Int](_.a)
                           .orElseBy[Int](_.b)
  28. def reverse: math.Ordering[Value]

    Return the opposite ordering of this one.

    Return the opposite ordering of this one.

    Implementations overriding this method MUST override isReverseOf as well if they change the behavior at all (for example, caching does not require overriding it).

    Definition Classes
    Ordering → PartialOrdering
  29. def reversed(): Comparator[Value]
    Definition Classes
    Comparator
  30. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  31. def thenComparing[U <: Comparable[_ >: U <: AnyRef]](arg0: java.util.function.Function[_ >: Value <: AnyRef, _ <: U]): Comparator[Value]
    Definition Classes
    Comparator
  32. def thenComparing[U <: AnyRef](arg0: java.util.function.Function[_ >: Value <: AnyRef, _ <: U], arg1: Comparator[_ >: U <: AnyRef]): Comparator[Value]
    Definition Classes
    Comparator
  33. def thenComparing(arg0: Comparator[_ >: Value <: AnyRef]): Comparator[Value]
    Definition Classes
    Comparator
  34. def thenComparingDouble(arg0: ToDoubleFunction[_ >: Value <: AnyRef]): Comparator[Value]
    Definition Classes
    Comparator
  35. def thenComparingInt(arg0: ToIntFunction[_ >: Value <: AnyRef]): Comparator[Value]
    Definition Classes
    Comparator
  36. def thenComparingLong(arg0: ToLongFunction[_ >: Value <: AnyRef]): Comparator[Value]
    Definition Classes
    Comparator
  37. 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
    AnyRef → Any
  38. def tryCompare(x: Value, y: Value): Some[Int]

    Returns whether a comparison between x and y is defined, and if so the result of compare(x, y).

    Returns whether a comparison between x and y is defined, and if so the result of compare(x, y).

    Definition Classes
    Ordering → PartialOrdering
  39. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  40. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  41. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()

Inherited from math.Ordering[Value]

Inherited from math.PartialOrdering[Value]

Inherited from math.Equiv[Value]

Inherited from java.io.Serializable

Inherited from Comparator[Value]

Inherited from AnyRef

Inherited from Any

Ungrouped