Export (0) Print
Expand All

ConstructorInfo Class

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

For a list of all members of this type, see ConstructorInfo Members.

System.Object
   System.Reflection.MemberInfo
      System.Reflection.MethodBase
         System.Reflection.ConstructorInfo
            System.Reflection.Emit.ConstructorBuilder

[Visual Basic]
<Serializable>
<ClassInterface(ClassInterfaceType.AutoDual)>
MustInherit Public Class ConstructorInfo
   Inherits MethodBase
[C#]
[Serializable]
[ClassInterface(ClassInterfaceType.AutoDual)]
public abstract class ConstructorInfo : MethodBase
[C++]
[Serializable]
[ClassInterface(ClassInterfaceType::AutoDual)]
public __gc __abstract class ConstructorInfo : public MethodBase
[JScript]
public
   Serializable
 ClassInterface(ClassInterfaceType.AutoDual)
abstract class ConstructorInfo extends MethodBase

Thread Safety

This type is safe for multithreaded operations.

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.

Notes to Inheritors:  When you inherit from ConstructorInfo, you must override the following member: Invoke(BindingFlags, Binder, Object, CultureInfo).

Example

[Visual Basic, C#, C++] 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

[C#] 
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);
        }
    }
}

[C++] 
#using <mscorlib.dll>

using namespace System;
using namespace System::Reflection;
using namespace System::Security;

public __gc class MyClass1 {
public:
   MyClass1(int i) {}
}
;
int main() {
   try {
      Type*  myType = __typeof(MyClass1);
      Type* types[] = new Type*[1];
      types->Item[0] = __typeof(int);
      // Get the public instance constructor that takes an integer parameter.
      ConstructorInfo*  constructorInfoObj = myType->GetConstructor(static_cast<BindingFlags>(BindingFlags::Instance | BindingFlags::Public), 0,
         CallingConventions::HasThis, types, 0);
      if (constructorInfoObj != 0) {
         Console::WriteLine(S"The constructor of MyClass1 that is a public instance method and takes an integer as a parameter is: ");
         Console::WriteLine(constructorInfoObj);
      } else {
         Console::WriteLine(S"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(S"ArgumentNullException: {0}", e->Message);
   } catch (ArgumentException* e) {
      Console::WriteLine(S"ArgumentException: {0}", e->Message);
   } catch (SecurityException* e) {
      Console::WriteLine(S"SecurityException: {0}", e->Message);
   } catch (Exception* e) {
      Console::WriteLine(S"Exception: {0}", e->Message);
   }
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Reflection

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: Mscorlib (in Mscorlib.dll)

See Also

ConstructorInfo Members | System.Reflection Namespace

Show:
© 2014 Microsoft