Object 类

  • 参考

定义

命名空间:
System
程序集:
System.Runtime.dll
程序集:
mscorlib.dll
程序集:
netstandard.dll

支持 .NET 类层次结构中的所有类，并为派生类提供低级别服务。 这是所有 .NET 类的最终基类；它是类型层次结构的根。

public ref class System::Object
public class Object
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.AutoDual)]
[System.Serializable]
public class Object
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.AutoDual)]
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public class Object
type obj = class
[<System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.AutoDual)>]
[<System.Serializable>]
type obj = class
[<System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.AutoDual)>]
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type obj = class
Public Class Object
属性
ClassInterfaceAttribute SerializableAttribute ComVisibleAttribute

示例

以下示例定义派生自该类的 Object Point 类型，并重写该类的许多 Object 虚拟方法。 此外，该示例还演示如何调用类的许多静态和实例方法 Object 。

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)
//

open System

// The Point class is derived from System.Object.
type Point(x, y) =
    member _.X = x
    member _.Y = y
    override _.Equals obj =
        // If this and obj do not refer to the same type, then they are not equal.
        match obj with
        | :? Point as other ->
            // Return true if  x and y fields match.
            x = other.X &&  y = other.Y
        | _ -> 
            false

    // Return the XOR of the x and y fields.
    override _.GetHashCode() =
        x ^^^ y

    // Return the point's value as a string.
    override _.ToString() =
        $"({x}, {y})"

    // Return a copy of this point object by making a simple field copy.
    member this.Copy() =
        this.MemberwiseClone() :?> Point

// Construct a Point object.
let p1 = Point(1,2)

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

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

// The line below displays false because p1 and p2 refer to two different objects.
printfn $"{Object.ReferenceEquals(p1, p2)}"

// The line below displays true because p1 and p2 refer to two different objects that have the same value.
printfn $"{Object.Equals(p1, p2)}"

// The line below displays true because p1 and p3 refer to one object.
printfn $"{Object.ReferenceEquals(p1, p3)}"

// The line below displays: p1's value is: (1, 2)
printfn $"p1's value is: {p1.ToString()}"
// This code example produces the following output:
//
// False
// True
// True
// p1's value is: (1, 2)
//

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)

' 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)
'

注解

语言通常不需要类来声明继承 Object ，因为继承是隐式的。

由于 .NET 中的所有类都派生自 Object，因此 Object 类中定义的每个方法都可用于系统中的所有对象。 派生类可以替代其中一些方法，包括：

  • Equals - 支持对象之间的比较。

  • Finalize - 在自动回收对象之前执行清理操作。

  • GetHashCode - 生成与对象值对应的数字，以支持使用哈希表。

  • ToString - 制造描述类实例的可读文本字符串。

性能注意事项

如果要设计必须处理任何类型的对象的类（如集合），则可以创建接受类实例的 Object 类成员。 但是，装箱和取消装箱类型的过程会产生性能成本。 如果你知道新类经常处理某些值类型，则可以使用两种策略之一来最大程度地降低装箱成本。

  • 创建一个接受 Object 类型的常规方法，以及一组特定于类型的方法重载，这些重载接受你期望类经常处理的每个值类型。 如果存在接受调用参数类型的特定于类型的方法，则不会发生任何装箱，并且调用特定于类型的方法。 如果没有与调用参数类型匹配的方法参数，则会对参数进行装箱，并调用常规方法。

  • 设计类型及其成员以使用泛型。 公共语言运行时在创建类的实例并指定泛型类型参数时，会创建一个封闭的泛型类型。 泛型方法特定于类型，无需装箱调用参数即可调用。

虽然有时有必要开发接受和返回 Object 类型的常规用途类，但还可以提供特定于类型的类来处理常用类型，从而提高性能。 例如，提供特定于设置和获取布尔值的类可消除装箱和取消装箱布尔值的成本。

构造函数

Object()

初始化 Object 类的新实例。

方法

Equals(Object)

确定指定对象是否等于当前对象。
Equals(Object, Object)

确定指定的对象实例是否被视为相等。
Finalize()

在垃圾回收将某一对象回收前允许该对象尝试释放资源并执行其他清理操作。
GetHashCode()

作为默认哈希函数。
GetType()

获取当前实例的 Type。
MemberwiseClone()

创建当前 Object 的浅表副本。
ReferenceEquals(Object, Object)

确定指定的 Object 实例是否是相同的实例。
ToString()

返回表示当前对象的字符串。

适用于

线程安全性

此类型的Visual Basic) 成员中的公共静态 (Shared是线程安全的。 不保证实例成员是线程安全的。