Object Classe

Definição

Dá suporte a todas as classes na hierarquia de classes do .NET e fornece serviços de baixo nível para as classes derivadas.Supports all classes in the .NET class hierarchy and provides low-level services to derived classes. Essa é a classe base final de todas as classes do .NET. É a raiz da hierarquia de tipo.This is the ultimate base class of all .NET classes; it is the root of the type hierarchy.

public ref class Object
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.AutoDual)]
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public class Object
type obj = class
Public Class Object
Atributos

Exemplos

O exemplo a seguir define um tipo de ponto derivado Object da classe e substitui muitos dos métodos virtuais Object da classe.The following example defines a Point type derived from the Object class and overrides many of the virtual methods of the Object class. Além disso, o exemplo mostra como chamar muitos dos métodos estáticos e de instância da Object classe.In addition, the example shows how to call many of the static and instance methods of the Object class.

using namespace System;

// The Point class is derived from System.Object.
ref class Point
{
public:
    int x;
public:
    int y;

public:
    Point(int x, int y)
    {
        this->x = x;
        this->y = y;
    }

public:
    virtual bool Equals(Object^ obj) override
    {
        // If this and obj do not refer to the same type,
        // then they are not equal.
        if (obj->GetType() != this->GetType())
        {
            return false;
        }

        // Return true if  x and y fields match.
        Point^ other = (Point^) obj;
        return (this->x == other->x) && (this->y == other->y);
    }

    // Return the XOR of the x and y fields.
public:
    virtual int GetHashCode() override 
    {
        return x ^ y;
    }

    // Return the point's value as a string.
public:
    virtual String^ ToString() override 
    {
        return String::Format("({0}, {1})", x, y);
    }

    // Return a copy of this point object by making a simple
    // field copy.
public:
    Point^ Copy()
    {
        return (Point^) this->MemberwiseClone();
    }
};

int main()
{
    // Construct a Point object.
    Point^ p1 = gcnew Point(1, 2);

    // Make another Point object that is a copy of the first.
    Point^ p2 = p1->Copy();

    // Make another variable that references the first
    // Point object.
    Point^ p3 = p1;

    // The line below displays false because p1 and 
    // p2 refer to two different objects.
    Console::WriteLine(
        Object::ReferenceEquals(p1, p2));

    // The line below displays true because p1 and p2 refer
    // to two different objects that have the same value.
    Console::WriteLine(Object::Equals(p1, p2));

    // The line below displays true because p1 and 
    // p3 refer to one object.
    Console::WriteLine(Object::ReferenceEquals(p1, p3));

    // The line below displays: p1's value is: (1, 2)
    Console::WriteLine("p1's value is: {0}", p1->ToString());
}

// This code produces the following output.
//
// False
// True
// True
// p1's value is: (1, 2)
using System;

// The Point class is derived from System.Object.
class Point
{
    public int x, y;

    public Point(int x, int y) 
    {
        this.x = x;
        this.y = y;
    }
    
    public override bool Equals(object obj) 
    {
        // If this and obj do not refer to the same type, then they are not equal.
        if (obj.GetType() != this.GetType()) return false;

        // Return true if  x and y fields match.
        var other = (Point) obj;
        return (this.x == other.x) && (this.y == other.y);
    }

    // Return the XOR of the x and y fields.
    public override int GetHashCode() 
    {
        return x ^ y;
    }

    // Return the point's value as a string.
    public override String ToString() 
    {
        return $"({x}, {y})";
    }

    // Return a copy of this point object by making a simple field copy.
    public Point Copy() 
    {
        return (Point) this.MemberwiseClone();
    }
}

public sealed class App
{
    static void Main() 
    {
        // Construct a Point object.
        var p1 = new Point(1,2);

        // Make another Point object that is a copy of the first.
        var p2 = p1.Copy();

        // Make another variable that references the first Point object.
        var p3 = p1;

        // The line below displays false because p1 and p2 refer to two different objects.
        Console.WriteLine(Object.ReferenceEquals(p1, p2));

        // The line below displays true because p1 and p2 refer to two different objects that have the same value.
        Console.WriteLine(Object.Equals(p1, p2));
      
        // The line below displays true because p1 and p3 refer to one object.
        Console.WriteLine(Object.ReferenceEquals(p1, p3));
        
        // The line below displays: p1's value is: (1, 2)
        Console.WriteLine($"p1's value is: {p1.ToString()}");
    }
}

// This code example produces the following output:
//
// False
// True
// True
// p1's value is: (1, 2)
//
' The Point class is derived from System.Object.
Class Point
    Public x, y As Integer
    
    Public Sub New(ByVal x As Integer, ByVal y As Integer) 
        Me.x = x
        Me.y = y
    End Sub
    
    Public Overrides Function Equals(ByVal obj As Object) As Boolean 
        ' If Me and obj do not refer to the same type, then they are not equal.
        Dim objType As Type = obj.GetType()
        Dim meType  As Type = Me.GetType()
        If Not objType.Equals(meType) Then
            Return False
        End If 
        ' Return true if  x and y fields match.
        Dim other As Point = CType(obj, Point)
        Return Me.x = other.x AndAlso Me.y = other.y
    End Function 

    ' Return the XOR of the x and y fields.
    Public Overrides Function GetHashCode() As Integer 
        Return (x << 1) XOR y
    End Function 

    ' Return the point's value as a string.
    Public Overrides Function ToString() As String 
        Return $"({x}, {y})"
    End Function

    ' Return a copy of this point object by making a simple field copy.
    Public Function Copy() As Point 
        Return CType(Me.MemberwiseClone(), Point)
    End Function
End Class  

NotInheritable Public Class App
    Shared Sub Main() 
        ' Construct a Point object.
        Dim p1 As New Point(1, 2)
        
        ' Make another Point object that is a copy of the first.
        Dim p2 As Point = p1.Copy()
        
        ' Make another variable that references the first Point object.
        Dim p3 As Point = p1
        
        ' The line below displays false because p1 and p2 refer to two different objects.
        Console.WriteLine([Object].ReferenceEquals(p1, p2))

        ' The line below displays true because p1 and p2 refer to two different objects 
        ' that have the same value.
        Console.WriteLine([Object].Equals(p1, p2))

        ' The line below displays true because p1 and p3 refer to one object.
        Console.WriteLine([Object].ReferenceEquals(p1, p3))
        
        ' The line below displays: p1's value is: (1, 2)
        Console.WriteLine($"p1's value is: {p1.ToString()}")
    
    End Sub
End Class
' This example produces the following output:
'
' False
' True
' True
' p1's value is: (1, 2)
'

Comentários

Os idiomas normalmente não exigem uma classe para declarar a herança Object porque a herança é implícita.Languages typically do not require a class to declare inheritance from Object because the inheritance is implicit.

Como todas as classes no .NET são derivadas Objectde, cada método definido Object na classe está disponível em todos os objetos no sistema.Because all classes in .NET are derived from Object, every method defined in the Object class is available in all objects in the system. As classes derivadas podem e substituem alguns desses métodos, incluindo:Derived classes can and do override some of these methods, including:

  • Equals– Dá suporte a comparações entre objetos.Equals - Supports comparisons between objects.

  • Finalize-Executa operações de limpeza antes que um objeto seja recuperado automaticamente.Finalize - Performs cleanup operations before an object is automatically reclaimed.

  • GetHashCode-Gera um número correspondente ao valor do objeto para dar suporte ao uso de uma tabela de hash.GetHashCode - Generates a number corresponding to the value of the object to support the use of a hash table.

  • ToString-Fabrica uma cadeia de texto legível por humanos que descreve uma instância da classe.ToString - Manufactures a human-readable text string that describes an instance of the class.

Considerações sobre desempenhoPerformance Considerations

Se você estiver criando uma classe, como uma coleção, que deve tratar de qualquer tipo de objeto, poderá criar membros de classe que aceitem instâncias da Object classe.If you are designing a class, such as a collection, that must handle any type of object, you can create class members that accept instances of the Object class. No entanto, o processo de conversão boxing e unboxing de um tipo transporta um custo de desempenho.However, the process of boxing and unboxing a type carries a performance cost. Se você souber que sua nova classe frequentemente tratará de certos tipos de valor, você poderá usar uma das duas táticas para minimizar o custo da boxing.If you know your new class will frequently handle certain value types you can use one of two tactics to minimize the cost of boxing.

  • Crie um método geral que aceite um Object tipo e um conjunto de sobrecargas de método específico de tipo que aceitam cada tipo de valor que você espera que sua classe manipule com freqüência.Create a general method that accepts an Object type, and a set of type-specific method overloads that accept each value type you expect your class to frequently handle. Se existir um método específico de tipo que aceite o tipo de parâmetro de chamada, nenhuma Boxing ocorrerá e o método específico de tipo será invocado.If a type-specific method exists that accepts the calling parameter type, no boxing occurs and the type-specific method is invoked. Se não houver nenhum argumento de método que corresponda ao tipo de parâmetro de chamada, o parâmetro será in box e o método geral será invocado.If there is no method argument that matches the calling parameter type, the parameter is boxed and the general method is invoked.

  • Projete seu tipo e seus membros para usar genéricos.Design your type and its members to use generics. O Common Language Runtime cria um tipo genérico fechado quando você cria uma instância de sua classe e especifica um argumento de tipo genérico.The common language runtime creates a closed generic type when you create an instance of your class and specify a generic type argument. O método genérico é específico de tipo e pode ser invocado sem boxing no parâmetro de chamada.The generic method is type-specific and can be invoked without boxing the calling parameter.

Embora às vezes seja necessário desenvolver classes de uso geral que aceitem e Object retornem tipos, você pode melhorar o desempenho fornecendo também uma classe específica de tipo para lidar com um tipo usado com frequência.Although it is sometimes necessary to develop general purpose classes that accept and return Object types, you can improve performance by also providing a type-specific class to handle a frequently used type. Por exemplo, fornecer uma classe específica para definir e obter valores Boolianos elimina o custo de valores Boolianos de boxing e unboxing.For example, providing a class that is specific to setting and getting Boolean values eliminates the cost of boxing and unboxing Boolean values.

Construtores

Object()

Inicializa uma nova instância da classe Object.Initializes a new instance of the Object class.

Métodos

Equals(Object)

Determina se o objeto especificado é igual ao objeto atual.Determines whether the specified object is equal to the current object.

Equals(Object, Object)

Determina se as instâncias de objeto especificadas são consideradas iguais.Determines whether the specified object instances are considered equal.

Finalize()

Permite que um objeto tente liberar recursos e executar outras operações de limpeza antes de ser recuperado pela coleta de lixo.Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.

GetHashCode()

Serve como a função de hash padrão.Serves as the default hash function.

GetType()

Obtém o Type da instância atual.Gets the Type of the current instance.

MemberwiseClone()

Cria uma cópia superficial do Object atual.Creates a shallow copy of the current Object.

ReferenceEquals(Object, Object)

Determina se as instâncias de Object especificadas são a mesma instância.Determines whether the specified Object instances are the same instance.

ToString()

Retorna uma cadeia de caracteres que representa o objeto atual.Returns a string that represents the current object.

Aplica-se a

Acesso thread-safe

Os membros estáticos públicos (Shared no Visual Basic) desse são thread-safe.Public static (Shared in Visual Basic) members of this type are thread safe. Não há garantia de que os membros da instância sejam thread-safe.Instance members are not guaranteed to be thread-safe.