IEquatable<T>.Equals(T) Método
Definição
Indica se o objeto atual é igual a outro objeto do mesmo tipo.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
Parâmetros
- other
- T
Um objeto para comparação com esse objeto.An object to compare with this object.
Retornos
true
se o objeto atual for igual ao parâmetro other
; caso contrário, false
.true
if the current object is equal to the other
parameter; otherwise, false
.
Exemplos
O exemplo a seguir mostra a implementação parcial de uma Person
classe que implementa IEquatable<T> e tem duas propriedades, LastName
e SSN
.The following example shows the partial implementation of a Person
class that implements IEquatable<T> and has two properties, LastName
and SSN
. O Equals método retornará True
se a SSN
propriedade de dois Person
objetos for idêntica; caso contrário, retornará 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
os objetos podem então ser armazenados em um List<T> objeto e podem ser identificados pelo Contains
método, como mostra o exemplo a seguir.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.
Comentários
A implementação do Equals método destina-se a executar um teste de igualdade com outro objeto do tipo T
, o mesmo tipo do objeto atual.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. O Equals(T) método é chamado nas seguintes circunstâncias:The Equals(T) method is called in the following circumstances:
Quando o
Equals
método é chamado e oother
argumento é um objeto fortemente tipado do tipoT
.When theEquals
method is called and theother
argument is a strongly-typed object of typeT
. (Seother
não for do tipoT
, o Object.Equals(Object) método base será chamado.(Ifother
is not of typeT
, the base Object.Equals(Object) method is called. Dos dois métodos, o IEquatable<T>.Equals oferece um desempenho ligeiramente melhor.)Of the two methods, IEquatable<T>.Equals offers slightly better performance.)Quando os métodos de pesquisa de vários objetos de coleção genéricos são chamados.When the search methods of a number of generic collection objects are called. Alguns desses tipos e seus métodos incluem o seguinte:Some of these types and their methods include the following:
Algumas das sobrecargas genéricas do BinarySearch método.Some of the generic overloads of the BinarySearch method.
Os métodos de pesquisa da List<T> classe, incluindo List<T>.Contains(T) , List<T>.IndexOf , List<T>.LastIndexOf e 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.
Os métodos de pesquisa da Dictionary<TKey,TValue> classe, incluindo ContainsKey e Remove .The search methods of the Dictionary<TKey,TValue> class, including ContainsKey and Remove.
Os métodos de pesquisa da LinkedList<T> classe genérica, incluindo LinkedList<T>.Contains e Remove .The search methods of the generic LinkedList<T> class, including LinkedList<T>.Contains and Remove.
Em outras palavras, para lidar com a possibilidade de que os objetos de uma classe sejam armazenados em uma matriz ou um objeto de coleção genérico, é uma boa ideia implementar IEquatable<T> para que o objeto possa ser facilmente identificado e manipulado.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.
Ao implementar o Equals método, defina a igualdade adequadamente para o tipo especificado pelo argumento de tipo genérico.When implementing the Equals method, define equality appropriately for the type specified by the generic type argument. Por exemplo, se o argumento de tipo for Int32 , defina igualdade adequadamente para a comparação de inteiros de 2 32 bits com sinal.For example, if the type argument is Int32, define equality appropriately for the comparison of two 32-bit signed integers.
Notas aos Implementadores
Se você implementar Equals(T) o, também deverá substituir as implementações de classe base de Equals(Object) e GetHashCode() , para que seu comportamento seja consistente com o do Equals(T) método.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. Se você substituir Equals(Object) , a implementação substituída também será chamada em chamadas para o Equals(System.Object, System.Object)
método estático em sua 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. Além disso, você deve sobrecarregar op_Equality
os op_Inequality
operadores e.In addition, you should overload the op_Equality
and op_Inequality
operators. Isso garante que todos os testes de igualdade retornem resultados consistentes, que o exemplo ilustra.This ensures that all tests for equality return consistent results, which the example illustrates.