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.

trait Comparable[A]
class Object
trait Matchable
class Any
class BigInt

Value members

Abstract methods

def compare(that: A): Int

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 methods

def <(that: A): Boolean

Returns true if this is less than that

def <=(that: A): Boolean

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

def >(that: A): Boolean

Returns true if this is greater than that.

def >=(that: A): Boolean

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

def compareTo(that: A): Int

Result of comparing this with operand that.