Packages

object Ordering extends LowPriorityOrderingImplicits with java.io.Serializable

This is the companion object for the scala.math.Ordering trait.

It contains many implicit orderings as well as well as methods to construct new orderings.

Source
Ordering.scala
Content Hierarchy
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  1. Ordering
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  3. LowPriorityOrderingImplicits
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Visibility
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Type Members

  1. type AsComparable[A] = (A) => Comparable[_ >: A]
  2. trait BigDecimalOrdering extends Ordering[BigDecimal]
  3. trait BigIntOrdering extends Ordering[BigInt]
  4. trait BooleanOrdering extends Ordering[Boolean]
  5. trait ByteOrdering extends Ordering[Byte]
  6. sealed trait CachedReverse[T] extends Ordering[T]

    An ordering which caches the value of its reverse.

  7. trait CharOrdering extends Ordering[Char]
  8. trait ExtraImplicits extends AnyRef
  9. trait IntOrdering extends Ordering[Int]
  10. trait LongOrdering extends Ordering[Long]
  11. trait OptionOrdering[T] extends Ordering[Option[T]]
  12. trait ShortOrdering extends Ordering[Short]
  13. trait StringOrdering extends Ordering[String]
  14. trait SymbolOrdering extends Ordering[Symbol]
  15. trait UnitOrdering extends Ordering[Unit]

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. implicit def Option[T](implicit ord: Ordering[T]): Ordering[Option[T]]
  5. implicit def Tuple2[T1, T2](implicit ord1: Ordering[T1], ord2: Ordering[T2]): Ordering[(T1, T2)]
  6. implicit def Tuple3[T1, T2, T3](implicit ord1: Ordering[T1], ord2: Ordering[T2], ord3: Ordering[T3]): Ordering[(T1, T2, T3)]
  7. implicit def Tuple4[T1, T2, T3, T4](implicit ord1: Ordering[T1], ord2: Ordering[T2], ord3: Ordering[T3], ord4: Ordering[T4]): Ordering[(T1, T2, T3, T4)]
  8. implicit def Tuple5[T1, T2, T3, T4, T5](implicit ord1: Ordering[T1], ord2: Ordering[T2], ord3: Ordering[T3], ord4: Ordering[T4], ord5: Ordering[T5]): Ordering[(T1, T2, T3, T4, T5)]
  9. implicit def Tuple6[T1, T2, T3, T4, T5, T6](implicit ord1: Ordering[T1], ord2: Ordering[T2], ord3: Ordering[T3], ord4: Ordering[T4], ord5: Ordering[T5], ord6: Ordering[T6]): Ordering[(T1, T2, T3, T4, T5, T6)]
    Annotations
    @SerialVersionUID()
  10. implicit def Tuple7[T1, T2, T3, T4, T5, T6, T7](implicit ord1: Ordering[T1], ord2: Ordering[T2], ord3: Ordering[T3], ord4: Ordering[T4], ord5: Ordering[T5], ord6: Ordering[T6], ord7: Ordering[T7]): Ordering[(T1, T2, T3, T4, T5, T6, T7)]
  11. implicit def Tuple8[T1, T2, T3, T4, T5, T6, T7, T8](implicit ord1: Ordering[T1], ord2: Ordering[T2], ord3: Ordering[T3], ord4: Ordering[T4], ord5: Ordering[T5], ord6: Ordering[T6], ord7: Ordering[T7], ord8: Ordering[T8]): Ordering[(T1, T2, T3, T4, T5, T6, T7, T8)]
    Annotations
    @SerialVersionUID()
  12. implicit def Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9](implicit ord1: Ordering[T1], ord2: Ordering[T2], ord3: Ordering[T3], ord4: Ordering[T4], ord5: Ordering[T5], ord6: Ordering[T6], ord7: Ordering[T7], ord8: Ordering[T8], ord9: Ordering[T9]): Ordering[(T1, T2, T3, T4, T5, T6, T7, T8, T9)]
    Annotations
    @SerialVersionUID()
  13. def apply[T](implicit ord: Ordering[T]): Ordering[T]
    Annotations
    @inline()
  14. 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.

  15. def by[T, S](f: (T) => S)(implicit ord: Ordering[S]): Ordering[T]

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

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

    def compare(x:T, y:T) = Ordering[S].compare(f(x), f(y))

    This function is an analogue to Ordering.on where the Ordering[S] parameter is passed implicitly.

  16. 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

  17. implicit def comparatorToOrdering[A](implicit cmp: Comparator[A]): Ordering[A]
  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(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
  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. def fromLessThan[T](cmp: (T, T) => Boolean): Ordering[T]

    Construct an Ordering[T] given a function lt.

  22. 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()
  23. 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()
  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. implicit def ordered[A](implicit asComparable: AsComparable[A]): Ordering[A]

    This would conflict with all the nice implicit Orderings available, but thanks to the magic of prioritized implicits via subclassing we can make Ordered[A] => Ordering[A] only turn up if nothing else works.

    This would conflict with all the nice implicit Orderings available, but thanks to the magic of prioritized implicits via subclassing we can make Ordered[A] => Ordering[A] only turn up if nothing else works. Since Ordered[A] extends Comparable[A] anyway, we can throw in some Java interop too.

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

    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-

    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-.

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

    not specified by SLS as a member of AnyRef

  34. implicit object BigDecimal extends BigDecimalOrdering
    Annotations
    @SerialVersionUID()
  35. implicit object BigInt extends BigIntOrdering
    Annotations
    @SerialVersionUID()
  36. implicit object Boolean extends BooleanOrdering
    Annotations
    @SerialVersionUID()
  37. implicit object Byte extends ByteOrdering
    Annotations
    @SerialVersionUID()
  38. implicit object Char extends CharOrdering
    Annotations
    @SerialVersionUID()
  39. implicit object DeprecatedDoubleOrdering extends TotalOrdering
    Annotations
    @migration @SerialVersionUID()
    Migration

    (Changed in version 2.13.0) The default implicit ordering for doubles now maintains consistency between its compare method and its lt, min, equiv, etc., methods, which means nonconforming to IEEE 754's behavior for -0.0 and NaN. The sort order of doubles remains the same, however, with NaN at the end. Import Ordering.Double.IeeeOrdering to recover the previous behavior. See also https://www.scala-lang.org/api/current/scala/math/Ordering$$Double$.html.

  40. implicit object DeprecatedFloatOrdering extends TotalOrdering
    Annotations
    @migration @SerialVersionUID()
    Migration

    (Changed in version 2.13.0) The default implicit ordering for floats now maintains consistency between its compare method and its lt, min, equiv, etc., methods, which means nonconforming to IEEE 754's behavior for -0.0F and NaN. The sort order of floats remains the same, however, with NaN at the end. Import Ordering.Float.IeeeOrdering to recover the previous behavior. See also https://www.scala-lang.org/api/current/scala/math/Ordering$$Float$.html.

  41. object Double

    Orderings for Doubles.

    Orderings for Doubles.

    The behavior of the comparison operations provided by the default (implicit) ordering on Double changed in 2.10.0 and 2.13.0. Prior to Scala 2.10.0, the Ordering instance used semantics consistent with java.lang.Double.compare.

    Scala 2.10.0 changed the implementation of lt, equiv, min, etc., to be IEEE 754 compliant, while keeping the compare method NOT compliant, creating an internally inconsistent instance. IEEE 754 specifies that 0.0 == -0.0. In addition, it requires all comparisons with Double.NaN return false thus 0.0 < Double.NaN, 0.0 > Double.NaN, and Double.NaN == Double.NaN all yield false, analogous None in flatMap.

    Recognizing the limitation of the IEEE 754 semantics in terms of ordering, Scala 2.13.0 created two instances: Ordering.Double.IeeeOrdering, which retains the IEEE 754 semantics from Scala 2.12.x, and Ordering.Double.TotalOrdering, which brings back the java.lang.Double.compare semantics for all operations. The default extends TotalOrdering.

    List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).sorted      // List(-Infinity, 0.0, 1.0, NaN)
    List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).min         // -Infinity
    implicitly[Ordering[Double]].lt(0.0, 0.0 / 0.0)   // true
    {
      import Ordering.Double.IeeeOrdering
      List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).sorted    // List(-Infinity, 0.0, 1.0, NaN)
      List(0.0, 1.0, 0.0 / 0.0, -1.0 / 0.0).min       // NaN
      implicitly[Ordering[Double]].lt(0.0, 0.0 / 0.0) // false
    }
  42. object Float

    Orderings for Floats.

    Orderings for Floats.

    The behavior of the comparison operations provided by the default (implicit) ordering on Float changed in 2.10.0 and 2.13.0. Prior to Scala 2.10.0, the Ordering instance used semantics consistent with java.lang.Float.compare.

    Scala 2.10.0 changed the implementation of lt, equiv, min, etc., to be IEEE 754 compliant, while keeping the compare method NOT compliant, creating an internally inconsistent instance. IEEE 754 specifies that 0.0F == -0.0F. In addition, it requires all comparisons with Float.NaN return false thus 0.0F < Float.NaN, 0.0F > Float.NaN, and Float.NaN == Float.NaN all yield false, analogous None in flatMap.

    Recognizing the limitation of the IEEE 754 semantics in terms of ordering, Scala 2.13.0 created two instances: Ordering.Float.IeeeOrdering, which retains the IEEE 754 semantics from Scala 2.12.x, and Ordering.Float.TotalOrdering, which brings back the java.lang.Float.compare semantics for all operations. The default extends TotalOrdering.

    List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).sorted      // List(-Infinity, 0.0, 1.0, NaN)
    List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).min         // -Infinity
    implicitly[Ordering[Float]].lt(0.0F, 0.0F / 0.0F)       // true
    {
      import Ordering.Float.IeeeOrdering
      List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).sorted    // List(-Infinity, 0.0, 1.0, NaN)
      List(0.0F, 1.0F, 0.0F / 0.0F, -1.0F / 0.0F).min       // NaN
      implicitly[Ordering[Float]].lt(0.0F, 0.0F / 0.0F)     // false
    }
  43. object Implicits extends ExtraImplicits

    An object containing implicits which are not in the default scope.

  44. implicit object Int extends IntOrdering with CachedReverse[Int]
    Annotations
    @SerialVersionUID()
  45. implicit object Long extends LongOrdering
    Annotations
    @SerialVersionUID()
  46. implicit object Short extends ShortOrdering
    Annotations
    @SerialVersionUID()
  47. implicit object String extends StringOrdering
    Annotations
    @SerialVersionUID()
  48. implicit object Symbol extends SymbolOrdering
    Annotations
    @SerialVersionUID()
  49. implicit object Unit extends UnitOrdering
    Annotations
    @SerialVersionUID()

Deprecated Value Members

  1. implicit def Iterable[T](implicit ord: Ordering[T]): Ordering[Iterable[T]]

    Annotations
    @deprecated
    Deprecated

    (Since version 2.13.0) Iterables are not guaranteed to have a consistent order; if using a type with a consistent order (e.g. Seq), use its Ordering (found in the Ordering.Implicits object)

Inherited from java.io.Serializable

Inherited from AnyRef

Inherited from Any

Ungrouped