# Ordering

#### trait Ordering [T] extends Comparator[T] with PartialOrdering[T] with Serializable

A trait for representing total orderings. It is important to distinguish between a type that has a total order and a representation of total ordering on some type. This trait is for the latter.

A ordering is a binary relation on a type `T` that is also an equivalence relation and partial ordering on values of type `T`. This relation is exposed as the `compare` method of the `Ordering` trait.

This relation must be:

```      reflexive:  x == x
antisymmetric:  if x <= y && y <= x, then x == y
transitive:  if x <= y && y <= z, then x <= z
```
Self Type
Ordering[T]
Annotations
( msg = ... )
Source
Ordering.scala
Version

0.9.5, 2008-04-15

Since

2.7

Linear Supertypes
Serializable, Serializable, PartialOrdering[T], Equiv[T], Comparator[T], AnyRef, Any
Ordering
1. Alphabetic
2. By inheritance
Inherited
1. Hide All
2. Show all
1. Ordering
2. Serializable
3. Serializable
4. PartialOrdering
5. Equiv
6. Comparator
7. AnyRef
8. Any
Visibility
1. Public
2. All

### Abstract Value Members

1. #### def compare (x: T, y: T): Int

Returns a negative integer iff `x` comes before `y` in the ordering, returns 0 iff `x` is the same in the ordering as `y`, and returns a positive number iff `x` comes after `y` in the ordering.

Returns a negative integer iff `x` comes before `y` in the ordering, returns 0 iff `x` is the same in the ordering as `y`, and returns a positive number iff `x` comes after `y` in the ordering.

Attributes
abstract
Definition Classes
Ordering → Comparator

### Concrete Value Members

1. #### def != (arg0: AnyRef): Boolean

Attributes
final
Definition Classes
AnyRef
2. #### def != (arg0: Any): Boolean

Test two objects for inequality.

Test two objects for inequality.

returns

`true` if !(this == that), false otherwise.

Attributes
final
Definition Classes
Any
3. #### def ## (): Int

Equivalent to `x.hashCode` except for boxed numeric types.

Equivalent to `x.hashCode` except for boxed numeric types. 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.

returns

a hash value consistent with ==

Attributes
final
Definition Classes
AnyRef → Any
4. #### def == (arg0: AnyRef): Boolean

Attributes
final
Definition Classes
AnyRef
5. #### def == (arg0: Any): Boolean

Test two objects for equality.

Test two objects for equality.

returns

`true` if the receiver object is equivalent to the argument; `false` otherwise.

Attributes
final
Definition Classes
Any
6. #### 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

Attributes
final
Definition Classes
Any
7. #### 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
()
8. #### def eq (arg0: AnyRef): Boolean

Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

Tests whether the argument (`arg0`) 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.

Attributes
final
Definition Classes
AnyRef
9. #### def equals (arg0: Any): Boolean

The equality method for reference types.

The equality method for reference types. See equals in Any.

returns

`true` if the receiver object is equivalent to the argument; `false` otherwise.

Definition Classes
AnyRef → Any
10. #### def equiv (x: T, y: T): Boolean

returns

true iff `x` is equivalent to `y` in the ordering.

Definition Classes
OrderingPartialOrderingEquiv
11. #### 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
()
12. #### def getClass (): java.lang.Class[_ <: java.lang.Object]

A representation that corresponds to the dynamic class of the receiver object.

A representation that corresponds to the dynamic class of the receiver object.

The nature of the representation is platform dependent.

returns

a representation that corresponds to the dynamic class of the receiver object.

Attributes
final
Definition Classes
AnyRef
13. #### def gt (x: T, y: T): Boolean

returns

true iff `y` comes before `x` in the ordering, and is not equal to `x`.

Definition Classes
OrderingPartialOrdering
14. #### def gteq (x: T, y: T): Boolean

returns

true iff `x` comes after `y` in the ordering, or is equal to `y`.

Definition Classes
OrderingPartialOrdering
15. #### def hashCode (): Int

The hashCode method for reference types.

The hashCode method for reference types. See hashCode in Any.

returns

the hash code value for this object.

Definition Classes
AnyRef → Any
16. #### def isInstanceOf [T0] : Boolean

Test whether the dynamic type of the receiver object is `T0`.

Test whether the dynamic type of the receiver object is `T0`.

Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. 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 specified type.

returns

`true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

Attributes
final
Definition Classes
Any
17. #### def lt (x: T, y: T): Boolean

returns

true iff `x` comes before `y` in the ordering, and is not equal to `y`.

Definition Classes
OrderingPartialOrdering
18. #### def lteq (x: T, y: T): Boolean

returns

true iff `x` comes before `y` in the ordering, or is equal to `y`.

Definition Classes
OrderingPartialOrdering
19. #### def max (x: T, y: T): T

Returns the argument which comes later in the ordering.

20. #### def min (x: T, y: T): T

Returns the argument which comes earlier in the ordering.

Attributes
implicit
22. #### 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.

Attributes
final
Definition Classes
AnyRef
23. #### 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.

Attributes
final
Definition Classes
AnyRef
24. #### 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.

Attributes
final
Definition Classes
AnyRef
25. #### def on [U] (f: (U) ⇒ T): Ordering[U]

Given a function U => T, creates Ordering[U].

26. #### def reverse : Ordering[T]

Definition Classes
OrderingPartialOrdering
27. #### def synchronized [T0] (arg0: ⇒ T0): T0

Attributes
final
Definition Classes
AnyRef
28. #### 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
29. #### def tryCompare (x: T, y: T): Some[Int]

An Ordering is defined at all x and y.

An Ordering is defined at all x and y.

Definition Classes
OrderingPartialOrdering
30. #### def wait (): Unit

Attributes
final
Definition Classes
AnyRef
Annotations
()
31. #### def wait (arg0: Long, arg1: Int): Unit

Attributes
final
Definition Classes
AnyRef
Annotations
()
32. #### def wait (arg0: Long): Unit

Attributes
final
Definition Classes
AnyRef
Annotations
()