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Type.GetConstructor Method (BindingFlags, Binder, Type(), ParameterModifier())

Searches for a constructor whose parameters match the specified argument types and modifiers, using the specified binding constraints.

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

'Declaration
<ComVisibleAttribute(True)> _
Public Function GetConstructor ( _
	bindingAttr As BindingFlags, _
	binder As Binder, _
	types As Type(), _
	modifiers As ParameterModifier() _
) As ConstructorInfo

Parameters

bindingAttr
Type: System.Reflection.BindingFlags

A bitmask comprised of one or more BindingFlags that specify how the search is conducted.

-or-

Zero, to return Nothing.

binder
Type: System.Reflection.Binder

An object that defines a set of properties and enables binding, which can involve selection of an overloaded method, coercion of argument types, and invocation of a member through reflection.

-or-

A null reference (Nothing in Visual Basic), to use the DefaultBinder.

types
Type: System.Type()

An array of Type objects representing the number, order, and type of the parameters for the constructor to get.

-or-

An empty array of the type Type (that is, Type[] types = new Type[0]) to get a constructor that takes no parameters.

-or-

EmptyTypes.

modifiers
Type: System.Reflection.ParameterModifier()

An array of ParameterModifier objects representing the attributes associated with the corresponding element in the parameter type array. The default binder does not process this parameter.

Return Value

Type: System.Reflection.ConstructorInfo
A ConstructorInfo object representing the constructor that matches the specified requirements, if found; otherwise, Nothing.

Implements

_Type.GetConstructor(BindingFlags, Binder, Type(), ParameterModifier())

ExceptionCondition
ArgumentNullException

types is Nothing.

-or-

One of the elements in types is Nothing.

ArgumentException

types is multidimensional.

-or-

modifiers is multidimensional.

-or-

types and modifiers do not have the same length.

If an exact match does not exist, the binder will attempt to coerce the parameter types specified in the types array in order to select a match. If the binder is unable to select a match, then Nothing is returned.

The following BindingFlags filter flags can be used to define which constructors to include in the search:

  • You must specify either BindingFlags.Instance or BindingFlags.Static in order to get a return.

  • Specify BindingFlags.Public to include public constructors in the search.

  • Specify BindingFlags.NonPublic to include non-public constructors (that is, private, internal, and protected constructors) in the search.

See System.Reflection.BindingFlags for more information.

To get the class initializer (.cctor) using this method overload, you must specify BindingFlags.Static | BindingFlags.NonPublic (BindingFlags.Static Or BindingFlags.NonPublic in Visual Basic). You can also get the class initializer using the TypeInitializer property.

NoteNote

You cannot omit parameters when looking up constructors and methods. You can only omit parameters when invoking.

If the current Type represents a constructed generic type, this method returns the ConstructorInfo with the type parameters replaced by the appropriate type arguments. If the current Type represents a type parameter in the definition of a generic type or generic method, this method always returns Nothing.

The following program obtains the type of MyClass1 class, gets the ConstructorInfo object matching the specified binding flags, and displays the signature of the constructor.

Imports System
Imports System.Reflection
Imports System.Security


Public Class MyClass1
    Public Sub New(ByVal i As Integer)
    End Sub 'New 

    Public Shared Sub Main()
        Try 
            Dim myType As Type = GetType(MyClass1)
            Dim types(0) As Type
            types(0) = GetType(Integer)
            ' Get the constructor that is public and takes an integer parameter. 
            Dim constructorInfoObj As ConstructorInfo = _
                     myType.GetConstructor(BindingFlags.Instance Or _
                     BindingFlags.Public, Nothing, types, Nothing)
            If Not (constructorInfoObj Is Nothing) Then
                Console.WriteLine("The constructor of MyClass1 that is " + _
                               "public and takes an integer as a parameter is ")
                Console.WriteLine(constructorInfoObj.ToString())
            Else
                Console.WriteLine("The constructor of MyClass1 that is " + _
                  "public 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

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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