Object 類別

  • 參考

定義

命名空間:
System
組件:
System.Runtime.dll
組件:
mscorlib.dll
組件:
netstandard.dll

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。 這是所有 .NET 類別的超基底類別，是類別階層架構的根。

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
屬性
ClassInterfaceAttribute SerializableAttribute ComVisibleAttribute

範例

下列範例會定義衍生自 類別的 Object Point 類型，並覆寫 類別的許多 Object 虛擬方法。 此外，此範例示範如何呼叫 類別的許多靜態和實例方法 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)
'

備註

語言通常不需要類別來宣告繼承， Object 因為繼承是隱含的。

因為 .NET 中的所有類別都是衍生自 Object ，所以類別中 Object 定義的每個方法都可以在系統中的所有物件中使用。 衍生類別可以並覆寫其中一些方法，包括：

  • Equals - 支持對象之間的比較。

  • Finalize - 在自動回收物件之前執行清除作業。

  • GetHashCode - 產生對應至 物件值的數位，以支援雜湊表的使用。

  • ToString - 製造人類可讀取的文字字串，描述 類別的實例。

效能考量

如果您要設計類別，例如必須處理任何類型的物件集合，您可以建立接受 類別實例的 Object 類別成員。 不過，Boxing 和 Unboxing 類型的程式具有效能成本。 如果您知道新的類別經常會處理特定實數值型別，您可以使用兩種策略之一，將 Boxing 的成本降到最低。

  • 建立接受類型的一 Object 般方法，以及一組類型特定的方法多載，以接受您預期類別經常處理的每個實值型別。 如果類型特定方法存在，且接受呼叫參數類型，則不會發生 Boxing，而且會叫用類型特定的方法。 如果沒有符合呼叫參數類型的方法引數，則會將參數 Boxed 並叫用一般方法。

  • 設計您的型別及其成員以使用泛型。 Common Language Runtime 會在您建立類別的實例並指定泛型型別引數時，建立封閉的泛型型別。 泛型方法是類型特定的方法，而且可以叫用，而不需將呼叫參數方塊化。

雖然有時需要開發接受和傳回 Object 型別的一般用途類別，但您也可以提供類型特定的類別來處理常用型別來改善效能。 例如，提供設定和取得布林值特有的類別，可消除 Boxing 和 Unboxing 布林值的成本。

建構函式

Object()

初始化 Object 類別的新執行個體。

方法

Equals(Object)

判斷指定的物件是否等於目前的物件。
Equals(Object, Object)

判斷指定的物件執行個體是否視為相等。
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。
GetHashCode()

做為預設雜湊函式。
GetType()

取得目前執行個體的 Type。
MemberwiseClone()

建立目前 Object 的淺層複製。
ReferenceEquals(Object, Object)

判斷指定的 Object 執行個體是否為相同的執行個體。
ToString()

傳回代表目前物件的字串。

適用於

執行緒安全性

此類型Visual Basic) 成員中的公用靜態 (Shared 是安全線程。 實例成員不保證為安全線程。