Type.Equals 方法

定义

命名空间:

System

程序集:

System.Runtime.dll

确定当前 Type 的基础系统类型是否与指定 Object 或 Type 的基础系统类型相同。

重载

Equals(Type)	确定当前 Type 的基础系统类型是否与指定 Type 的基础系统类型相同。
Equals(Object)	确定当前 Type 的基础系统类型是否与指定 Object 的基础系统类型相同。

Equals(Type)

Source:

Type.cs

确定当前 Type 的基础系统类型是否与指定 Type 的基础系统类型相同。

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

参数

o

Type

该对象，其基础系统类型将与当前 Type 的基础系统类型相比较。

返回

Boolean

如果 true 的基础系统类型与当前 o 的基础系统类型相同，则为 Type；否则为 false。

示例

以下示例使用 Equals 来比较两种类型。

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
'

另请参阅

• UnderlyingSystemType

Equals(Object)

Source:

Type.cs

确定当前 Type 的基础系统类型是否与指定 Object 的基础系统类型相同。

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

参数

o

Object

该对象，其基础系统类型将与当前 Type 的基础系统类型相比较。 要使比较成功， o 必须能够强制转换或转换为 类型的 Type对象。

返回

Boolean

如果 true 的基础系统类型与当前 o 的基础系统类型相同，则为 Type；否则为 false。 在以下情况下，此方法也会返回 false：

• o 为 null。

• o 不能强制转换或转换为 Type 对象。

示例

以下示例使用 Equals(Object) 将各种对象实例与各种TypeObject实例进行比较。

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.

关于此示例，有两点特别值得注意：

• 表示整数的 Type 对象与 TypeInfo 表示整数返回 true 的对象的比较，因为 TypeInfo 派生自 Type。

• 表示打开泛型类型) 对象 (对象与封闭泛型类型 (对象的比较TypeIList<T>) 返回 false。List(Of String)

注解

此方法重写 Object.Equals。 它强制转换为 o 类型的 Type 对象并调用 Type.Equals(Type) 方法。

另请参阅

• UnderlyingSystemType