ConstructorInfo Class (System.Reflection)

Collapse All

Language Filter

This page is specific to

Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

ConstructorInfo Class

Updated: November 2007

Discovers the attributes of a class constructor and provides access to constructor metadata.

Namespace: System.Reflection
Assembly: mscorlib (in mscorlib.dll)

Syntax

Visual Basic (Declaration)

<SerializableAttribute> _
<ComVisibleAttribute(True)> _
<ClassInterfaceAttribute(ClassInterfaceType.None)> _
<PermissionSetAttribute(SecurityAction.InheritanceDemand, Name := "FullTrust")> _
Public MustInherit Class ConstructorInfo _
    Inherits MethodBase _
    Implements _ConstructorInfo

Visual Basic (Usage)

Dim instance As ConstructorInfo

[SerializableAttribute]
[ComVisibleAttribute(true)]
[ClassInterfaceAttribute(ClassInterfaceType.None)]
[PermissionSetAttribute(SecurityAction.InheritanceDemand, Name = "FullTrust")]
public abstract class ConstructorInfo : MethodBase, 
    _ConstructorInfo

Visual C++

[SerializableAttribute]
[ComVisibleAttribute(true)]
[ClassInterfaceAttribute(ClassInterfaceType::None)]
[PermissionSetAttribute(SecurityAction::InheritanceDemand, Name = L"FullTrust")]
public ref class ConstructorInfo abstract : public MethodBase, 
    _ConstructorInfo

/** @attribute SerializableAttribute */ 
/** @attribute ComVisibleAttribute(true) */
/** @attribute ClassInterfaceAttribute(ClassInterfaceType.None) */
/** @attribute PermissionSetAttribute(SecurityAction.InheritanceDemand, Name = "FullTrust") */
public abstract class ConstructorInfo extends MethodBase implements _ConstructorInfo

JScript

public abstract class ConstructorInfo extends MethodBase implements _ConstructorInfo

Remarks

ConstructorInfo is used to discover the attributes of a constructor as well as to invoke a constructor. Objects are created by calling Invoke on a ConstructorInfo returned by either the GetConstructors or GetConstructor method of a Type object.

Note:
ConstructorInfo inherits from MethodBase several members, such as IsGenericMethod, that can be used to examine generic methods. In the .NET Framework version 2.0 constructors cannot be generic, so these members return false or nullNothingnullptra null reference (Nothing in Visual Basic).

Notes to Inheritors:

When you inherit from ConstructorInfo, you must override the following member overload: Invoke(BindingFlags, Binder, array<Object>[]()[], CultureInfo).

Examples

The following example uses ConstructorInfo with GetConstructor and BindingFlags to find the constructors that match the specified search criteria.

Visual Basic

Public Class MyClass1
    Public Sub New(ByVal i As Integer)
    End Sub
    Public Shared Sub Main()
        Try
            Dim myType As Type = GetType(MyClass1)
            Dim types(0) As Type
            types(0) = GetType(Integer)
            ' Get the public instance constructor that takes an integer parameter.
            Dim constructorInfoObj As ConstructorInfo = _
                        myType.GetConstructor(BindingFlags.Instance Or _
                        BindingFlags.Public, Nothing, _
                        CallingConventions.HasThis, types, Nothing)
            If Not (constructorInfoObj Is Nothing) Then
                Console.WriteLine("The constructor of MyClass1 that " + _
                                  "is a public instance method and takes an " + _
                                  "integer as a parameter is: ")
                Console.WriteLine(constructorInfoObj.ToString())
            Else
                Console.WriteLine("The constructor MyClass1 that " + _
                                  "is a public instance method and takes an " + _
                                  "integer as a parameter is not available.")
            End If
        Catch e As ArgumentNullException
            Console.WriteLine("ArgumentNullException: " + e.Message)
        Catch e As ArgumentException
            Console.WriteLine("ArgumentException: " + e.Message)
        Catch e As SecurityException
            Console.WriteLine("SecurityException: " + e.Message)
        Catch e As Exception
            Console.WriteLine("Exception: " + e.Message)
        End Try
    End Sub
End Class

using System;
using System.Reflection;
using System.Security;

public class MyClass1
{
    public MyClass1(int i){}
    public static void Main()
    {
        try
        {
            Type  myType = typeof(MyClass1);
            Type[] types = new Type[1];
            types[0] = typeof(int);
            // Get the public instance constructor that takes an integer parameter.
            ConstructorInfo constructorInfoObj = myType.GetConstructor(
                BindingFlags.Instance | BindingFlags.Public, null,
                CallingConventions.HasThis, types, null);
            if(constructorInfoObj != null)
            {
                Console.WriteLine("The constructor of MyClass1 that is a public " +
                    "instance method and takes an integer as a parameter is: ");
                Console.WriteLine(constructorInfoObj.ToString());
            }
            else
            {
                Console.WriteLine("The constructor of MyClass1 that is a public instance " +
                    "method and takes an integer as a parameter is not available.");
            }
        }
        catch(ArgumentNullException e)
        {
            Console.WriteLine("ArgumentNullException: " + e.Message);
        }
        catch(ArgumentException e)
        {
            Console.WriteLine("ArgumentException: " + e.Message);
        }
        catch(SecurityException e)
        {
            Console.WriteLine("SecurityException: " + e.Message);
        }
        catch(Exception e)
        {
            Console.WriteLine("Exception: " + e.Message);
        }
    }
}

Visual C++

using namespace System;
using namespace System::Reflection;
using namespace System::Security;
public ref class MyClass1
{
public:
   MyClass1( int i ){}

};

int main()
{
   try
   {
      Type^ myType = MyClass1::typeid;
      array<Type^>^types = gcnew array<Type^>(1);
      types[ 0 ] = int::typeid;

      // Get the public instance constructor that takes an integer parameter.
      ConstructorInfo^ constructorInfoObj = myType->GetConstructor( static_cast<BindingFlags>(BindingFlags::Instance | BindingFlags::Public), nullptr, CallingConventions::HasThis, types, nullptr );
      if ( constructorInfoObj != nullptr )
      {
         Console::WriteLine( "The constructor of MyClass1 that is a public instance method and takes an integer as a parameter is: " );
         Console::WriteLine( constructorInfoObj );
      }
      else
      {
         Console::WriteLine( "The constructor of MyClass1 that is a public instance method and takes an integer as a parameter is not available." );
      }
   }
   catch ( ArgumentNullException^ e ) 
   {
      Console::WriteLine( "ArgumentNullException: {0}", e->Message );
   }
   catch ( ArgumentException^ e ) 
   {
      Console::WriteLine( "ArgumentException: {0}", e->Message );
   }
   catch ( SecurityException^ e ) 
   {
      Console::WriteLine( "SecurityException: {0}", e->Message );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception: {0}", e->Message );
   }
}

import System.*;
import System.Reflection.*;
import System.Security.*;

public class MyClass1
{
    public MyClass1(int i)
    {
    } //MyClass1

    public static void main(String[] args)
    {
        try {
            Type myType = MyClass1.class.ToType();
            Type types[] = new Type[1];
            types.set_Item(0, int.class.ToType());
            // Get the public instance constructor that takes an
            // integer parameter.
            ConstructorInfo constructorInfoObj =
                myType.GetConstructor(BindingFlags.Instance|BindingFlags.Public,
                null, CallingConventions.HasThis, types, null);
            if (constructorInfoObj != null) {
                Console.WriteLine("The constructor of MyClass1 that is a public "
                    + "instance method and takes an integer as a parameter is: ");
                Console.WriteLine(constructorInfoObj.ToString());
            }
            else {
                Console.WriteLine("The constructor of MyClass1 that is a "
                    + "public instance method and takes an integer "
                    + "as a parameter is not available.");
            }
        }
        catch (ArgumentNullException e) {
            Console.WriteLine("ArgumentNullException: " + e.get_Message());
        }
        catch (ArgumentException e) {
            Console.WriteLine("ArgumentException: " + e.get_Message());
        }
        catch (SecurityException e) {
            Console.WriteLine("SecurityException: " + e.get_Message());
        }
        catch (System.Exception e) {
            Console.WriteLine("Exception: " + e.get_Message());
        }
    } //main
} //MyClass1

Inheritance Hierarchy

System..::.Object
  System.Reflection..::.MemberInfo
    System.Reflection..::.MethodBase
      System.Reflection..::.ConstructorInfo
        Microsoft.JScript..::.JSConstructor
        System.Reflection.Emit..::.ConstructorBuilder

Thread Safety

This type is thread safe.

Platforms

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information