 Ordering

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

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 representing the latter.

A total orderingis 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: compare(x, x) == 0, for any x of type T.
• symmetry: compare(x, y) == z and compare(y, x) == wthen math.signum(z) == -math.signum(w), for any x and y of type T and z and w of type Int.
• transitive: if compare(x, y) == z and compare(y, w) == vand math.signum(z) &gt;= 0 and math.signum(v) &gt;= 0 thencompare(x, w) == u and math.signum(z + v) == math.signum(u), for any x, y, and w of type T and z, v, and uof type Int.
go to: companion
source: Ordering.scala
version
1. 0.9.5, 2008-04-15

since
1. 2.7

authors:
1. Geoffrey Washburn

Inherited
1. Hide All
2. Show all
1. PartialOrdering
2. Equiv
3. Comparator
4. AnyRef
5. Any
Visibility
1. Public
2. All

Value Members

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

attributes: final
definition classes: AnyRef
2. def !=(arg0: Any): Boolean

o != arg0 is the same as !(o == (arg0)).

o != arg0 is the same as !(o == (arg0)).

arg0

the object to compare against this object for dis-equality.

returns

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

attributes: final
definition classes: Any
3. def ##(): Int

attributes: final
definition classes: AnyRef → Any
4. def \$asInstanceOf[T0](): T0

attributes: final
definition classes: AnyRef
5. def \$isInstanceOf[T0](): Boolean

attributes: final
definition classes: AnyRef
6. def ==(arg0: AnyRef): Boolean

o == arg0 is the same as if (o eq null) arg0 eq null else o.equals(arg0).

o == arg0 is the same as if (o eq null) arg0 eq null else o.equals(arg0).

arg0

the object to compare against this object for equality.

returns

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

attributes: final
definition classes: AnyRef
7. def ==(arg0: Any): Boolean

o == arg0 is the same as o.equals(arg0).

o == arg0 is the same as o.equals(arg0).

arg0

the object to compare against this object for equality.

returns

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

attributes: final
definition classes: Any
8. def asInstanceOf[T0]: T0

This method is used to cast the receiver object to be of type T0.

This method is used to 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 expression1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expressionList(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 typed.

returns

attributes: final
definition classes: Any
9. def clone(): AnyRef

This method creates and returns a copy of the receiver object.

This method creates and returns 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
definition classes: AnyRef
10. def compare(x: T, y: T): Int

Returns a negative integer iff x comes beforey in the ordering, returns 0 iff xis the same in the ordering as y, and returns a positive number iff x comes aftery in the ordering.

Returns a negative integer iff x comes beforey in the ordering, returns 0 iff xis the same in the ordering as y, and returns a positive number iff x comes aftery in the ordering.

attributes: abstract
definition classes: Ordering → Comparator
11. def eq(arg0: AnyRef): Boolean

This method is used to test whether the argument (arg0) is a reference to the receiver object (this).

This method is used to test whether the argument (arg0) is a reference to the receiver object (this).

The eq method implements an [http://en.wikipedia.org/wiki/Equivalence_relation equivalence relation] on non-null instances of AnyRef: * It is reflexive: for any non-null instance x of type AnyRef, x.eq(x) returns true. * It is symmetric: for any non-null instances x and y of type AnyRef, x.eq(y) returns true if and only if y.eq(x) returns true. * It is transitive: for any non-null instances x, y, and z of type AnyRef if x.eq(y) returns true and y.eq(z) returns true, then x.eq(z) returns true.

Additionally, the eq method has three other 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).

arg0

the object to compare against this object for reference equality.

returns

true if the argument is a reference to the receiver object; false otherwise.

attributes: final
definition classes: AnyRef
12. def equals(arg0: Any): Boolean

This method is used to compare the receiver object (this) with the argument object (arg0) for equivalence.

This method is used to compare the receiver object (this) with the argument object (arg0) for equivalence.

The default implementations of this method is an [http://en.wikipedia.org/wiki/Equivalence_relation equivalence relation]: * It is reflexive: for any instance x of type Any, x.equals(x) should return true. * It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true. * It is transitive: for any instances x, y, and z of type AnyRef if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.

If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is often necessary to override hashCode to ensure that objects that are "equal" (o1.equals(o2) returns true) hash to the same scala.Int (o1.hashCode.equals(o2.hashCode)).

arg0

the object to compare against this object for equality.

returns

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

definition classes: AnyRef → Any
13. def equiv(x: T, y: T): Boolean

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

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

definition classes: OrderingPartialOrderingEquiv
14. def finalize(): Unit

This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.

This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.

The details of when and if the finalize method are invoked, as well as the interaction between finalizeand non-local returns and exceptions, are all platform dependent.

attributes: protected
definition classes: AnyRef
15. def getClass(): java.lang.Class[_ <: java.lang.Object]

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

Returns 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
16. def gt(x: T, y: T): Boolean

Returns true iff y comes before x in the ordering and is not the same as x.

Returns true iff y comes before x in the ordering and is not the same as x.

definition classes: OrderingPartialOrdering
17. def gteq(x: T, y: T): Boolean

Returns true iff y comes before x in the ordering.

Returns true iff y comes before x in the ordering.

definition classes: OrderingPartialOrdering
18. def hashCode(): Int

Returns a hash code value for the object.

Returns a hash code value for the object.

The default hashing algorithm is platform dependent.

Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

returns

the hash code value for the object.

definition classes: AnyRef → Any
19. def isInstanceOf[T0]: Boolean

This method is used to test whether the dynamic type of the receiver object is T0.

This method is used to test whether the dynamic type of the receiver object is T0.

Note that the test result of the test is modulo Scala's erasure semantics. Therefore the expression1.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 requested typed.

returns

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

attributes: final
definition classes: Any
20. def lt(x: T, y: T): Boolean

Returns true iff x comes before y in the ordering and is not the same as y.

Returns true iff x comes before y in the ordering and is not the same as y.

definition classes: OrderingPartialOrdering
21. def lteq(x: T, y: T): Boolean

Returns true iff x comes before y in the ordering.

Returns true iff x comes before y in the ordering.

definition classes: OrderingPartialOrdering
22. def max(x: T, y: T): T

Returns the argument which comes later in the ordering.

Returns the argument which comes later in the ordering.

23. def min(x: T, y: T): T

Returns the argument which comes earlier in the ordering.

Returns the argument which comes earlier in the ordering.

24. implicit def mkOrderingOps(lhs: T): Ops

attributes: implicit
25. def ne(arg0: AnyRef): Boolean

o.ne(arg0) is the same as !(o.eq(arg0)).

o.ne(arg0) is the same as !(o.eq(arg0)).

arg0

the object to compare against this object for reference dis-equality.

returns

false if the argument is not a reference to the receiver object; true otherwise.

attributes: final
definition classes: AnyRef
26. 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
27. 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
28. def on[U](f: (U) ⇒ T): Ordering[U]

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

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

29. def reverse: Ordering[T]

definition classes: OrderingPartialOrdering
30. def synchronized[T0](arg0: T0): T0

attributes: final
definition classes: AnyRef
31. def toString(): String

Returns a string representation of the object.

Returns a string representation of the object.

The default representation is platform dependent.

returns

a string representation of the object.

definition classes: AnyRef → Any
32. 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
33. def wait(): Unit

attributes: final
definition classes: AnyRef
34. def wait(arg0: Long, arg1: Int): Unit

attributes: final
definition classes: AnyRef
35. def wait(arg0: Long): Unit

attributes: final
definition classes: AnyRef