Packages

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.

Source
Ordered.scala
Version

1.1, 2006-07-24

See also

scala.math.Ordering, scala.math.PartiallyOrdered

Linear Supertypes
Comparable[A], Any
Known Subclasses
Val, Value, StringLike, StringOps, WrappedString, StringBuilder, Deadline, Duration, Infinite, FiniteDuration, BigDecimal, BigInt, FractionalProxy, IntegralProxy, OrderedProxy, RichBoolean, RichByte, RichChar, RichDouble, RichFloat, RichInt, RichLong, RichShort, ScalaNumberProxy, ScalaWholeNumberProxy
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. Ordered
  2. Comparable
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. All

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

Concrete Value Members

  1. def <(that: A): Boolean

    Returns true if this is less than that

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

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

  3. def >(that: A): Boolean

    Returns true if this is greater than that.

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

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

  5. def compareTo(that: A): Int

    Result of comparing this with operand that.

    Result of comparing this with operand that.

    Definition Classes
    Ordered → Comparable