Object 類別

定義

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

以下範例定義了從類別 Object 衍生出的點型態，並覆蓋了該 Object 類別的許多虛擬方法。 此外，範例展示了如何呼叫該類別的 Object 許多靜態與實例方法。

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)
//

' 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

類別 Object 是所有 .NET 類別的最終基類;它是類型階層的根目錄。

由於 .NET 中的所有類別都是衍生自 Object，因此類別中 Object 定義的每個方法都可在系統中的所有物件中使用。 衍生類別可以覆寫其中一些方法，包括：

• Equals：支援對象之間的比較。
• 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，以支援哈希表的使用。
• ToString：製造人類可讀取的文字字串，描述 類別的實例。

語言通常不需要類別來宣告繼承， Object 因為繼承是隱含的。

效能考量

如果您要設計一個類別，比如一個必須處理任何類型物件的集合，您可以建立接受 Object 類別實例的類別成員。 不過，資料型別的裝箱和拆箱過程會帶來效能損耗。 如果您知道新類別會經常處理某些實值型別，您可以使用兩種策略之一，將 Boxing 的成本降到最低。

• 建立可接受Object類型的通用方法，以及一組特定類型的方法多載，以處理您預期類別經常處理的每種實值類型。 如果存在一個接受呼叫參數類型的類型特定方法，則不會發生裝箱，並且會叫用該類型特定方法。 如果沒有與呼叫參數類型相匹配的方法參數，則會將參數封裝並調用一般方法。
• 設計您的類型及其成員以使用 泛型。 當您建立 類別的實例並指定泛型類型自變數時，Common Language Runtime 會建立封閉式泛型類型。 泛型方法具有類型專屬特性，可以在不需要將呼叫參數裝箱的情況下被叫用。

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，提供用於設置及獲取布爾值的特定類別，可以消除裝箱和拆箱布爾值的開銷。

執行緒安全性

此類型的公用靜態 （Shared） 成員是安全線程。 實例成員不保證執行緒安全。