Object 類別

定義

支援 .NET 類別階層架構中的所有類別,提供衍生類別的低階服務。Supports all classes in the .NET class hierarchy and provides low-level services to derived classes. 這是所有 .NET 類別的超基底類別,是類別階層架構的根。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
屬性

範例

下列範例會定義衍生自 Object 類別的 Point 型別,並覆寫 Object 類別的許多虛擬方法。The following example defines a Point type derived from the Object class and overrides many of the virtual methods of the Object class. 此外,此範例也會示範如何呼叫 Object 類別的許多靜態和實例方法。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)
'

備註

語言通常不需要類別來宣告來自 Object 的繼承,因為繼承是隱含的。Languages typically do not require a class to declare inheritance from Object because the inheritance is implicit.

由於 .NET 中的所有類別都是衍生自 Object,因此 Object 類別中定義的每個方法都可用於系統中的所有物件。Because all classes in .NET are derived from Object, every method defined in the Object class is available in all objects in the system. 衍生類別可以和覆寫其中一些方法,包括:Derived classes can and do override some of these methods, including:

  • Equals-支持對象之間的比較。Equals - Supports comparisons between objects.

  • Finalize-在自動回收物件之前執行清除作業。Finalize - Performs cleanup operations before an object is automatically reclaimed.

  • GetHashCode-產生對應于物件值的數位,以支援雜湊資料表的使用。GetHashCode - Generates a number corresponding to the value of the object to support the use of a hash table.

  • ToString 製造可讀取的文字字串,以描述類別的實例。ToString - Manufactures a human-readable text string that describes an instance of the class.

效能考量Performance Considerations

如果您要設計的類別(例如集合)必須處理任何類型的物件,您可以建立接受 Object 類別之實例的類別成員。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. 不過,將類型裝箱和取消裝箱的程式會帶來效能成本。However, the process of boxing and unboxing a type carries a performance cost. 如果您知道新的類別經常會處理特定的實值型別,您可以使用兩種策略的其中一種來將裝箱成本降到最低。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.

  • 建立可接受 Object 類型的一般方法,以及一組特定類型的方法多載,其接受您預期類別經常處理的每個實數值型別。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. 如果存在可接受呼叫參數類型的特定類型方法,則不會進行任何裝箱,而且會叫用特定類型的方法。If a type-specific method exists that accepts the calling parameter type, no boxing occurs and the type-specific method is invoked. 如果沒有符合呼叫參數類型的方法引數,則會將參數裝箱並叫用一般方法。If there is no method argument that matches the calling parameter type, the parameter is boxed and the general method is invoked.

  • 設計您的類型及其成員,以使用泛型。Design your type and its members to use generics. 當您建立類別的實例並指定泛型型別引數時,common language runtime 會建立封閉式泛型型別。The common language runtime creates a closed generic type when you create an instance of your class and specify a generic type argument. 泛型方法是特定類型,而且可以叫用,而不需要將呼叫參數裝箱。The generic method is type-specific and can be invoked without boxing the calling parameter.

雖然有時必須開發接受並傳回 Object 類型的一般目的類別,但您也可以提供特定類型的類別來處理常用的類型,以改善效能。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. 例如,提供設定和取得布林值所特有的類別,可免除對布林值進行裝箱和取消裝箱的成本。For example, providing a class that is specific to setting and getting Boolean values eliminates the cost of boxing and unboxing Boolean values.

建構函式

Object()

初始化 Object 類別的新執行個體。Initializes a new instance of the Object class.

方法

Equals(Object)

判斷指定的物件是否等於目前的物件。Determines whether the specified object is equal to the current object.

Equals(Object, Object)

判斷指定的物件執行個體是否視為相等。Determines whether the specified object instances are considered equal.

Finalize()

允許物件在記憶體回收進行回收之前,嘗試釋放資源並執行其他清除作業。Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.

GetHashCode()

作為預設雜湊函數。Serves as the default hash function.

GetType()

取得目前執行個體的 TypeGets the Type of the current instance.

MemberwiseClone()

建立目前 Object 的淺層複製。Creates a shallow copy of the current Object.

ReferenceEquals(Object, Object)

判斷指定的 Object 執行個體是否為相同的執行個體。Determines whether the specified Object instances are the same instance.

ToString()

傳回代表目前物件的字串。Returns a string that represents the current object.

適用於

執行緒安全性

此類型的公用靜態(Shared 在 Visual Basic 中)成員是安全線程。Public static (Shared in Visual Basic) members of this type are thread safe. 不保證實例成員是安全線程。Instance members are not guaranteed to be thread-safe.