IEquatable<T>.Equals(T) Méthode
Définition
Indique si l'objet actuel est égal à un autre objet du même type.Indicates whether the current object is equal to another object of the same type.
public:
bool Equals(T other);
public bool Equals (T other);
public bool Equals (T? other);
abstract member Equals : 'T -> bool
Public Function Equals (other As T) As Boolean
Paramètres
- other
- T
Objet à comparer à cet objet.An object to compare with this object.
Retours
true
si l'objet actuel est égal au paramètre other
; sinon, false
.true
if the current object is equal to the other
parameter; otherwise, false
.
Exemples
L’exemple suivant montre l’implémentation partielle d’une Person
classe qui implémente IEquatable<T> et a deux propriétés, LastName
et SSN
.The following example shows the partial implementation of a Person
class that implements IEquatable<T> and has two properties, LastName
and SSN
. La Equals méthode retourne True
si la SSN
propriété de deux Person
objets est identique ; sinon, elle retourne False
.The Equals method returns True
if the SSN
property of two Person
objects is identical; otherwise, it returns False
.
using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
public class Person : IEquatable<Person>
{
private string uniqueSsn;
private string lName;
public Person(string lastName, string ssn)
{
if (Regex.IsMatch(ssn, @"\d{9}"))
uniqueSsn = $"{ssn.Substring(0, 3)}-{ssn.Substring(3, 2)}-{ssn.Substring(5, 4)}";
else if (Regex.IsMatch(ssn, @"\d{3}-\d{2}-\d{4}"))
uniqueSsn = ssn;
else
throw new FormatException("The social security number has an invalid format.");
this.LastName = lastName;
}
public string SSN
{
get { return this.uniqueSsn; }
}
public string LastName
{
get { return this.lName; }
set {
if (String.IsNullOrEmpty(value))
throw new ArgumentException("The last name cannot be null or empty.");
else
this.lName = value;
}
}
public bool Equals(Person other)
{
if (other == null)
return false;
if (this.uniqueSsn == other.uniqueSsn)
return true;
else
return false;
}
public override bool Equals(Object obj)
{
if (obj == null)
return false;
Person personObj = obj as Person;
if (personObj == null)
return false;
else
return Equals(personObj);
}
public override int GetHashCode()
{
return this.SSN.GetHashCode();
}
public static bool operator == (Person person1, Person person2)
{
if (((object)person1) == null || ((object)person2) == null)
return Object.Equals(person1, person2);
return person1.Equals(person2);
}
public static bool operator != (Person person1, Person person2)
{
if (((object)person1) == null || ((object)person2) == null)
return ! Object.Equals(person1, person2);
return ! (person1.Equals(person2));
}
}
Imports System.Collections.Generic
Imports System.Text.RegularExpressions
Public Class Person : Implements IEquatable(Of Person)
Private uniqueSsn As String
Private lName As String
Public Sub New(lastName As String, ssn As String)
If Regex.IsMatch(ssn, "\d{9}") Then
uniqueSsn = $"{ssn.Substring(0, 3)}-{ssn.Substring(3, 2)}-{ssn.Substring(5, 4)}"
ElseIf Regex.IsMatch(ssn, "\d{3}-\d{2}-\d{4}") Then
uniqueSsn = ssn
Else
Throw New FormatException("The social security number has an invalid format.")
End If
Me.LastName = lastName
End Sub
Public ReadOnly Property SSN As String
Get
Return Me.uniqueSsn
End Get
End Property
Public Property LastName As String
Get
Return Me.lName
End Get
Set
If String.IsNullOrEmpty(value) Then
Throw New ArgumentException("The last name cannot be null or empty.")
Else
lname = value
End If
End Set
End Property
Public Overloads Function Equals(other As Person) As Boolean _
Implements IEquatable(Of Person).Equals
If other Is Nothing Then Return False
If Me.uniqueSsn = other.uniqueSsn Then
Return True
Else
Return False
End If
End Function
Public Overrides Function Equals(obj As Object) As Boolean
If obj Is Nothing Then Return False
Dim personObj As Person = TryCast(obj, Person)
If personObj Is Nothing Then
Return False
Else
Return Equals(personObj)
End If
End Function
Public Overrides Function GetHashCode() As Integer
Return Me.SSN.GetHashCode()
End Function
Public Shared Operator = (person1 As Person, person2 As Person) As Boolean
If person1 Is Nothing OrElse person2 Is Nothing Then
Return Object.Equals(person1, person2)
End If
Return person1.Equals(person2)
End Operator
Public Shared Operator <> (person1 As Person, person2 As Person) As Boolean
If person1 Is Nothing OrElse person2 Is Nothing Then
Return Not Object.Equals(person1, person2)
End If
Return Not person1.Equals(person2)
End Operator
End Class
Person
les objets peuvent ensuite être stockés dans un List<T> objet et peuvent être identifiés par la Contains
méthode, comme le montre l’exemple suivant.Person
objects can then be stored in a List<T> object and can be identified by the Contains
method, as the following example shows.
public class TestIEquatable
{
public static void Main()
{
// Create a Person object for each job applicant.
Person applicant1 = new Person("Jones", "099-29-4999");
Person applicant2 = new Person("Jones", "199-29-3999");
Person applicant3 = new Person("Jones", "299-49-6999");
// Add applicants to a List object.
List<Person> applicants = new List<Person>();
applicants.Add(applicant1);
applicants.Add(applicant2);
applicants.Add(applicant3);
// Create a Person object for the final candidate.
Person candidate = new Person("Jones", "199-29-3999");
if (applicants.Contains(candidate))
Console.WriteLine("Found {0} (SSN {1}).",
candidate.LastName, candidate.SSN);
else
Console.WriteLine("Applicant {0} not found.", candidate.SSN);
// Call the shared inherited Equals(Object, Object) method.
// It will in turn call the IEquatable(Of T).Equals implementation.
Console.WriteLine("{0}({1}) already on file: {2}.",
applicant2.LastName,
applicant2.SSN,
Person.Equals(applicant2, candidate));
}
}
// The example displays the following output:
// Found Jones (SSN 199-29-3999).
// Jones(199-29-3999) already on file: True.
Module TestIEquatable
Public Sub Main()
' Create a Person object for each job applicant.
Dim applicant1 As New Person("Jones", "099-29-4999")
Dim applicant2 As New Person("Jones", "199-29-3999")
Dim applicant3 As New Person("Jones", "299-49-6999")
' Add applicants to a List object.
Dim applicants As New List(Of Person)
applicants.Add(applicant1)
applicants.Add(applicant2)
applicants.Add(applicant3)
' Create a Person object for the final candidate.
Dim candidate As New Person("Jones", "199-29-3999")
If applicants.Contains(candidate) Then
Console.WriteLine("Found {0} (SSN {1}).", _
candidate.LastName, candidate.SSN)
Else
Console.WriteLine("Applicant {0} not found.", candidate.SSN)
End If
' Call the shared inherited Equals(Object, Object) method.
' It will in turn call the IEquatable(Of T).Equals implementation.
Console.WriteLine("{0}({1}) already on file: {2}.", _
applicant2.LastName, _
applicant2.SSN, _
Person.Equals(applicant2, candidate))
End Sub
End Module
' The example displays the following output:
' Found Jones (SSN 199-29-3999).
' Jones(199-29-3999) already on file: True.
Remarques
L’implémentation de la Equals méthode est conçue pour effectuer un test d’égalité avec un autre objet de type T
, le même type que l’objet actuel.The implementation of the Equals method is intended to perform a test for equality with another object of type T
, the same type as the current object. La Equals(T) méthode est appelée dans les circonstances suivantes :The Equals(T) method is called in the following circumstances:
Lorsque la
Equals
méthode est appelée et que l'other
argument est un objet fortement typé de typeT
.When theEquals
method is called and theother
argument is a strongly-typed object of typeT
. (Siother
n’est pas de typeT
, la Object.Equals(Object) méthode de base est appelée.(Ifother
is not of typeT
, the base Object.Equals(Object) method is called. Parmi les deux méthodes, IEquatable<T>.Equals offre des performances légèrement meilleures.)Of the two methods, IEquatable<T>.Equals offers slightly better performance.)Lorsque les méthodes de recherche d’un certain nombre d’objets de collection générique sont appelées.When the search methods of a number of generic collection objects are called. Parmi ces types et leurs méthodes, citons les suivantes :Some of these types and their methods include the following:
Certaines des surcharges génériques de la BinarySearch méthode.Some of the generic overloads of the BinarySearch method.
Méthodes de recherche de la List<T> classe, y compris List<T>.Contains(T) ,, List<T>.IndexOf List<T>.LastIndexOf et List<T>.Remove .The search methods of the List<T> class, including List<T>.Contains(T), List<T>.IndexOf, List<T>.LastIndexOf, and List<T>.Remove.
Méthodes de recherche de la Dictionary<TKey,TValue> classe, y compris ContainsKey et Remove .The search methods of the Dictionary<TKey,TValue> class, including ContainsKey and Remove.
Les méthodes de recherche de la LinkedList<T> classe générique, y compris LinkedList<T>.Contains et Remove .The search methods of the generic LinkedList<T> class, including LinkedList<T>.Contains and Remove.
En d’autres termes, pour gérer la possibilité que les objets d’une classe soient stockés dans un tableau ou un objet de collection générique, il est préférable d’implémenter IEquatable<T> afin que l’objet puisse être facilement identifié et manipulé.In other words, to handle the possibility that objects of a class will be stored in an array or a generic collection object, it is a good idea to implement IEquatable<T> so that the object can be easily identified and manipulated.
Lors de l’implémentation de la Equals méthode, définissez l’égalité de manière appropriée pour le type spécifié par l’argument de type générique.When implementing the Equals method, define equality appropriately for the type specified by the generic type argument. Par exemple, si l’argument de type est Int32 , définissez l’égalité de manière appropriée pour la comparaison des entiers signés 2 32 bits.For example, if the type argument is Int32, define equality appropriately for the comparison of two 32-bit signed integers.
Notes pour les responsables de l’implémentation
Si vous implémentez Equals(T) , vous devez également substituer les implémentations de classe de base de Equals(Object) et GetHashCode() afin que leur comportement soit cohérent avec celui de la Equals(T) méthode.If you implement Equals(T), you should also override the base class implementations of Equals(Object) and GetHashCode() so that their behavior is consistent with that of the Equals(T) method. Si vous substituez Equals(Object) , votre implémentation substituée est également appelée dans les appels à la Equals(System.Object, System.Object)
méthode statique sur votre classe.If you do override Equals(Object), your overridden implementation is also called in calls to the static Equals(System.Object, System.Object)
method on your class. En outre, vous devez surcharger les op_Equality
op_Inequality
opérateurs et.In addition, you should overload the op_Equality
and op_Inequality
operators. Cela garantit que tous les tests d’égalité retournent des résultats cohérents, comme l’illustre l’exemple.This ensures that all tests for equality return consistent results, which the example illustrates.