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:

    • scala.reflect - Scala's reflection API (scala-reflect.jar)
    • scala.xml - XML parsing, manipulation, and serialization (scala-xml.jar)
    • scala.swing - A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)
    • scala.util.parsing - Parser combinators (scala-parser-combinators.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 evaluation.

    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
  }
  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

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], Serializable, 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. Serializable
  7. Comparator
  8. AnyRef
  9. Any
  1. Hide All
  2. Show All
Visibility
  1. Public
  2. All

Type Members

  1. class Ops 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. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. def max(x: Value, y: Value): Value

    Return x if x >= y, otherwise y.

    Return x if x >= y, otherwise y.

    Definition Classes
    Ordering
  8. def min(x: Value, y: Value): Value

    Return x if x <= y, otherwise y.

    Return x if x <= y, otherwise y.

    Definition Classes
    Ordering
  9. implicit def mkOrderingOps(lhs: Value): Ops

    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
  10. 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
  11. def reverse: math.Ordering[Value]

    Return the opposite ordering of this one.

    Return the opposite ordering of this one.

    Definition Classes
    Ordering → PartialOrdering
  12. def reversed(): Comparator[Value]
    Definition Classes
    Comparator
  13. def thenComparing[U <: Comparable[_ >: U]](arg0: java.util.function.Function[_ >: Value, _ <: U]): Comparator[Value]
    Definition Classes
    Comparator
  14. def thenComparing[U](arg0: java.util.function.Function[_ >: Value, _ <: U], arg1: Comparator[_ >: U]): Comparator[Value]
    Definition Classes
    Comparator
  15. def thenComparing(arg0: Comparator[_ >: Value]): Comparator[Value]
    Definition Classes
    Comparator
  16. def thenComparingDouble(arg0: ToDoubleFunction[_ >: Value]): Comparator[Value]
    Definition Classes
    Comparator
  17. def thenComparingInt(arg0: ToIntFunction[_ >: Value]): Comparator[Value]
    Definition Classes
    Comparator
  18. def thenComparingLong(arg0: ToLongFunction[_ >: Value]): Comparator[Value]
    Definition Classes
    Comparator
  19. 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