Type.Equals 方法

定義

命名空間:

System

組件:

System.Runtime.dll

判斷目前 Type 的基礎系統類型，是否與指定的 Object 或 Type 的基礎系統類型相同。

多載

Equals(Type)	判斷目前 Type 的基礎系統類型，是否與指定的 Type 之基礎系統類型相同。
Equals(Object)	判斷目前 Type 物件的基礎系統類型，是否與指定的 Object 的基礎系統類型相同。

Equals(Type)

來源:

Type.cs

判斷目前 Type 的基礎系統類型，是否與指定的 Type 之基礎系統類型相同。

public:
 virtual bool Equals(Type ^ o);

public virtual bool Equals (Type? o);

override this.Equals : Type -> bool

Public Overridable Function Equals (o As Type) As Boolean

參數

o

Type

其基礎系統類型將與目前 Type 的基礎系統類型比較的物件。

傳回

Boolean

如果 true 的基礎系統類型與目前 o 的基礎系統類型相同，則為 Type否則為 false。

範例

下列範例會使用 Equals 來比較兩種類型。

using System;
using System.Reflection;

class Example
{
    public static void Main()
    {

        Type a = typeof(System.String);
        Type b = typeof(System.Int32);

        Console.WriteLine("{0} == {1}: {2}", a, b, a.Equals(b));

        // The Type objects in a and b are not equal,
        // because they represent different types.

        a = typeof(Example);
        b = new Example().GetType();

        Console.WriteLine("{0} is equal to {1}: {2}", a, b, a.Equals(b));

        // The Type objects in a and b are equal,
        // because they both represent type Example.

        b = typeof(Type);

        Console.WriteLine("typeof({0}).Equals(typeof({1})): {2}", a, b, a.Equals(b));

        // The Type objects in a and b are not equal,
        // because variable a represents type Example
        // and variable b represents type Type.

        //Console.ReadLine();
    }
}

//
/* This code example produces the following output:
    System.String == System.Int32: False
    Example is equal to Example: True
    typeof(Example).Equals(typeof(System.Type)): False
*/

open System

type Example() = class end

do
    let a = typeof<string>
    let b = typeof<int>

    printfn $"{a} == {b}: {a.Equals b}"

    // The Type objects in a and b are not equal,
    // because they represent different types.

    let a = typeof<Example>
    let b = Example().GetType()

    printfn $"{a} is equal to {b}: {a.Equals b}"

    // The Type objects in a and b are equal,
    // because they both represent type Example.

    let b = typeof<Type>

    printfn $"typeof({a}).Equals(typeof({b})): {a.Equals b}"

// The Type objects in a and b are not equal,
// because variable a represents type Example
// and variable b represents type Type.

(* This code example produces the following output:
    System.String == System.Int32: False
    Example is equal to Example: True
    typeof(Example).Equals(typeof(System.Type)): False
*)

Imports System.Reflection



Class Example
    
    Public Shared Sub Main() 
        
        Dim a As Type = GetType(System.String)
        Dim b As Type = GetType(System.Int32)
        
        Console.WriteLine("{0} = {1}: {2}", a, b, a.Equals(b))
        ' The Type objects in a and b are not equal,
        ' because they represent different types.

        a = GetType(Example)
        b = New Example().GetType()
        Console.WriteLine("{0} is equal to {1}: {2}", a, b, a.Equals(b))
        ' The Type objects in a and b are equal,
        ' because they both represent type Example.

        b = GetType(Type)
        Console.WriteLine("typeof({0}).Equals(typeof({1})): {2}", a, b, a.Equals(b))
        ' The Type objects in a and b are not equal,
        ' because variable a represents type Example
        ' and variable b represents type Type.

        'Console.ReadLine()
    
    End Sub 
End Class
'
' This code example produces the following output:
'    System.String = System.Int32: False
'    Example is equal to Example: True
'    typeof(Example).Equals(typeof(System.Type)): False
'

另請參閱

• UnderlyingSystemType

Equals(Object)

來源:

Type.cs

判斷目前 Type 物件的基礎系統類型，是否與指定的 Object 的基礎系統類型相同。

public:
 override bool Equals(System::Object ^ o);

public override bool Equals (object? o);

override this.Equals : obj -> bool

Public Overrides Function Equals (o As Object) As Boolean

參數

o

Object

其基礎系統類型將與目前 Type 的基礎系統類型比較的物件。 若要讓比較成功， o 必須能夠轉換或轉換成 類型 Type 的物件。

傳回

Boolean

如果 true 的基礎系統類型與目前 o 的基礎系統類型相同，則為 Type否則為 false。 如果是下列情況，這個方法也會傳回 false：

• o 為 null。

• o 無法轉型或轉換為 Type 物件。

範例

下列範例會使用 Equals(Object) 來比較各種 Type 物件實例與各種 Object 實例。

using System;
using System.Collections.Generic;
using System.Reflection;

public class Example
{
   public static void Main()
   {
      Type t =typeof(int);
      Object obj1 = typeof(int).GetTypeInfo();
      IsEqualTo(t, obj1);

      Object obj2 = typeof(String);
      IsEqualTo(t, obj2);
      
      t = typeof(Object);
      Object obj3 = typeof(Object);
      IsEqualTo(t, obj3);
      
      t = typeof(List<>);
      Object obj4 = (new List<String>()).GetType();
      IsEqualTo(t, obj4);
      
      t = typeof(Type);
      Object obj5 = null;
      IsEqualTo(t, obj5);
   }
   
   private static void IsEqualTo(Type t, Object inst)
   {
      Type t2 = inst as Type;
      if (t2 != null)
         Console.WriteLine("{0} = {1}: {2}", t.Name, t2.Name,
                           t.Equals(t2));
      else
         Console.WriteLine("Cannot cast the argument to a type.");

      Console.WriteLine();                        
   }
}
// The example displays the following output:
//       Int32 = Int32: True
//       
//       Int32 = String: False
//       
//       Object = Object: True
//       
//       List`1 = List`1: False
//       
//       Cannot cast the argument to a type.

open System
open System.Reflection

let isEqualTo (t: Type) (inst: obj) =
    match inst with
    | :? Type as t2 ->
        printfn $"{t.Name} = {t2.Name}: {t.Equals t2}\n"
    | _ ->
        printfn "Cannot cast the argument to a type.\n"

do 
    let t = typeof<int>
    typeof<int>.GetTypeInfo()
    |> isEqualTo t

    typeof<String>
    |> isEqualTo t

    let t = typeof<obj>
    typeof<obj>
    |> isEqualTo t

    let t = typeof<ResizeArray<_>>.GetGenericTypeDefinition()
    let obj4: obj = (ResizeArray<String>()).GetType()
    isEqualTo t obj4

    let t = typeof<Type>
    let obj5: obj = null
    isEqualTo t obj5
// The example displays the following output:
//       Int32 = Int32: True
//       
//       Int32 = String: False
//       
//       Object = Object: True
//       
//       List`1 = List`1: False
//       
//       Cannot cast the argument to a type.

Imports System.Collections.Generic
Imports System.Reflection

Module Example
   Public Sub Main()
      Dim t As Type = GetType(Integer)
      Dim obj1 As Object = GetType(Integer).GetTypeInfo()
      IsEqualTo(t, obj1)

      Dim obj2 As Object = GetType(String)
      IsEqualTo(t, obj2)
      
      t = GetType(Object)
      Dim obj3 As Object = GetType(Object)
      IsEqualTo(t, obj3)
      
      t = GetType(List(Of ))
      Dim obj4 As Object = (New List(Of String())).GetType()
      IsEqualTo(t, obj4)
      
      t = GetType(Type)
      Dim obj5 As Object = Nothing
      IsEqualTo(t, obj5)
   End Sub
   
   Private Sub IsEqualTo(t As Type, inst As Object)
      Dim t2 As Type = TryCast(inst, Type)
      If t2 IsNot Nothing Then
         Console.WriteLine("{0} = {1}: {2}", t.Name, t2.Name,
                           t.Equals(t2))
      Else
         Console.WriteLine("Cannot cast the argument to a type.")
      End If
      Console.WriteLine()                        
   End Sub
End Module
' The example displays the following output:
'       Int32 = Int32: True
'       
'       Int32 = String: False
'       
'       Object = Object: True
'       
'       List`1 = List`1: False
'       
'       Cannot cast the argument to a type.

這兩件事特別值得注意範例：

• 物件比較 Type ，該物件代表整數，且 TypeInfo 物件代表整數傳回 true ，因為 TypeInfo 衍生自 Type 。

• 物件比較 Type ，表示 IList<T> 物件 (開啟泛型型別) 物件 List(Of String) ， (封閉式泛型型別) 傳 false 回 。

備註

這個方法會覆寫 Object.Equals。 它會轉換成 o 型 Type 別的物件，並呼叫 Type.Equals(Type) 方法。

另請參閱

• UnderlyingSystemType