scala.math

Ordered

trait Ordered[A] extends Comparable[A]

A trait for data that have a single, natural ordering. See scala.math.Ordering before using this trait for more information about whether to use scala.math.Ordering instead.

Classes that implement this trait can be sorted with scala.util.Sorting and can be compared with standard comparison operators (e.g. > and <).

Ordered should be used for data with a single, natural ordering (like integers) while Ordering allows for multiple ordering implementations. An Ordering instance will be implicitly created if necessary.

scala.math.Ordering is an alternative to this trait that allows multiple orderings to be defined for the same type.

scala.math.PartiallyOrdered is an alternative to this trait for partially ordered data.

For example, create a simple class that implements Ordered and then sort it with scala.util.Sorting:

case class OrderedClass(n:Int) extends Ordered[OrderedClass] {
	def compare(that: OrderedClass) =  this.n - that.n
}

val x = Array(OrderedClass(1), OrderedClass(5), OrderedClass(3))
scala.util.Sorting.quickSort(x)
x

It is important that the equals method for an instance of Ordered[A] be consistent with the compare method. However, due to limitations inherent in the type erasure semantics, there is no reasonable way to provide a default implementation of equality for instances of Ordered[A]. Therefore, if you need to be able to use equality on an instance of Ordered[A] you must provide it yourself either when inheriting or instantiating.

It is important that the hashCode method for an instance of Ordered[A] be consistent with the compare method. However, it is not possible to provide a sensible default implementation. Therefore, if you need to be able compute the hash of an instance of Ordered[A] you must provide it yourself either when inheriting or instantiating.

Version

1.1, 2006-07-24

See also

scala.math.Ordering, scala.math.PartiallyOrdered

Linear Supertypes
Comparable[A], Any
Known Subclasses
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Ordering
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Inherited
  1. Ordered
  2. Comparable
  3. Any
Implicitly
  1. by orderingToOrdered
  2. by any2stringadd
  3. by StringFormat
  4. by Ensuring
  5. by ArrowAssoc
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Abstract Value Members

  1. abstract def compare(that: A): 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
  2. abstract def getClass(): Class[_]

    Definition Classes
    Any

Concrete Value Members

  1. final def !=(arg0: Any): Boolean

    Definition Classes
    Any
  2. final def ##(): Int

    Definition Classes
    Any
  3. def +(other: String): String

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to any2stringadd[Ordered[A]] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (Ordered[A], B)

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to ArrowAssoc[Ordered[A]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. def <(that: A): Boolean

    Returns true if this is less than that

  6. def <=(that: A): Boolean

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

  7. final def ==(arg0: Any): Boolean

    Definition Classes
    Any
  8. def >(that: A): Boolean

    Returns true if this is greater than that.

  9. def >=(that: A): Boolean

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

  10. final def asInstanceOf[T0]: T0

    Definition Classes
    Any
  11. def compareTo(that: A): Int

    Result of comparing this with operand that.

    Result of comparing this with operand that.

    Definition Classes
    Ordered → Comparable
  12. def ensuring(cond: (Ordered[A]) ⇒ Boolean, msg: ⇒ Any): Ordered[A]

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ensuring[Ordered[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. def ensuring(cond: (Ordered[A]) ⇒ Boolean): Ordered[A]

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ensuring[Ordered[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  14. def ensuring(cond: Boolean, msg: ⇒ Any): Ordered[A]

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ensuring[Ordered[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  15. def ensuring(cond: Boolean): Ordered[A]

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ensuring[Ordered[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  16. def equals(arg0: Any): Boolean

    Definition Classes
    Any
  17. 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 information
    This member is added by an implicit conversion from Ordered[A] to StringFormat[Ordered[A]] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  18. def hashCode(): Int

    Definition Classes
    Any
  19. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any
  20. def toString(): String

    Definition Classes
    Any
  21. def [B](y: B): (Ordered[A], B)

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to ArrowAssoc[Ordered[A]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Shadowed Implicit Value Members

  1. def <(that: Ordered[A]): Boolean

    Returns true if this is less than that

    Returns true if this is less than that

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ordered[Ordered[A]] performed by method orderingToOrdered in scala.math.Ordered. This conversion will take place only if an implicit value of type Ordering[Ordered[A]] 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:
    (ordered: Ordered[Ordered[A]]).<(that)
  2. def <=(that: Ordered[A]): Boolean

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

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

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ordered[Ordered[A]] performed by method orderingToOrdered in scala.math.Ordered. This conversion will take place only if an implicit value of type Ordering[Ordered[A]] 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:
    (ordered: Ordered[Ordered[A]]).<=(that)
  3. def >(that: Ordered[A]): Boolean

    Returns true if this is greater than that.

    Returns true if this is greater than that.

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ordered[Ordered[A]] performed by method orderingToOrdered in scala.math.Ordered. This conversion will take place only if an implicit value of type Ordering[Ordered[A]] 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:
    (ordered: Ordered[Ordered[A]]).>(that)
  4. def >=(that: Ordered[A]): Boolean

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

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

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ordered[Ordered[A]] performed by method orderingToOrdered in scala.math.Ordered. This conversion will take place only if an implicit value of type Ordering[Ordered[A]] 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:
    (ordered: Ordered[Ordered[A]]).>=(that)
  5. def compare(that: Ordered[A]): 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 information
    This member is added by an implicit conversion from Ordered[A] to Ordered[Ordered[A]] performed by method orderingToOrdered in scala.math.Ordered. This conversion will take place only if an implicit value of type Ordering[Ordered[A]] 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:
    (ordered: Ordered[Ordered[A]]).compare(that)
  6. def compareTo(that: Ordered[A]): Int

    Result of comparing this with operand that.

    Result of comparing this with operand that.

    Implicit information
    This member is added by an implicit conversion from Ordered[A] to Ordered[Ordered[A]] performed by method orderingToOrdered in scala.math.Ordered. This conversion will take place only if an implicit value of type Ordering[Ordered[A]] 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:
    (ordered: Ordered[Ordered[A]]).compareTo(that)
    Definition Classes
    Ordered → Comparable

Inherited from Comparable[A]

Inherited from Any

Inherited by implicit conversion orderingToOrdered from Ordered[A] to Ordered[Ordered[A]]

Inherited by implicit conversion any2stringadd from Ordered[A] to any2stringadd[Ordered[A]]

Inherited by implicit conversion StringFormat from Ordered[A] to StringFormat[Ordered[A]]

Inherited by implicit conversion Ensuring from Ordered[A] to Ensuring[Ordered[A]]

Inherited by implicit conversion ArrowAssoc from Ordered[A] to ArrowAssoc[Ordered[A]]

Ungrouped