Artikel
11/18/2011

Type.GetConstructor Method (array<Type[])

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Searches for a public instance constructor whose parameters match the types in the specified array.

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

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Function GetConstructor ( _
    types As Type() _
) As ConstructorInfo

[ComVisibleAttribute(true)]
public ConstructorInfo GetConstructor(
    Type[] types
)

Parameters

types
Type: array<System.Type[]
An array of Type objects representing the number, order, and type of the parameters for the desired constructor.
-or-
An empty array of Type objects, to get a constructor that takes no parameters. Such an empty array is provided by the static field Type.EmptyTypes.

Return Value

Type: System.Reflection.ConstructorInfo
A ConstructorInfo object representing the public instance constructor whose parameters match the types in the parameter type array, if found; otherwise, nulla null reference (Nothing in Visual Basic).

Exceptions

Exception	Condition
ArgumentNullException	types is nulla null reference (Nothing in Visual Basic). -or- One of the elements in types is nulla null reference (Nothing in Visual Basic).
ArgumentException	types is multidimensional.

ArgumentNullException

types is nulla null reference (Nothing in Visual Basic).

-or-

One of the elements in types is nulla null reference (Nothing in Visual Basic).

ArgumentException

types is multidimensional.

Remarks

This method overload looks for public instance constructors and cannot be used to obtain a class initializer (.cctor). To get a class initializer, use an overload that takes BindingFlags, and specify BindingFlags.Static | BindingFlags.NonPublic (BindingFlags.StaticOrBindingFlags.NonPublic in Visual Basic).

If the requested constructor is non-public, this method returns nulla null reference (Nothing in Visual Basic).

Note:
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 nulla null reference (Nothing in Visual Basic).

Examples

The following example obtains the type of MyClass, gets the ConstructorInfo object, and displays the constructor signature.

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.

Imports System.Reflection
Imports System.Security

Public Class Example

    Public Sub New()
    End Sub 

    Public Sub New(ByVal i As Integer)
    End Sub 

    Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

         Dim myType As Type = GetType(Example)
         Dim parameters() As Type = { GetType(Int32) }

         ' Get the constructor that takes an integer as a parameter.
         Dim ctor As ConstructorInfo = myType.GetConstructor(parameters)

         If ctor Is Nothing Then
             outputBlock.Text &= _
                 "There is no public constructor of MyClass that takes an integer as a parameter." & vbCrLf
         Else
             outputBlock.Text &= _
                 "The public constructor of MyClass that takes an integer as a parameter is: " & vbCrLf
             outputBlock.Text &= ctor.ToString() & vbCrLf
         End If

    End Sub 
End Class 

' This example produces the following output:
'
'The public constructor of MyClass that takes an integer as a parameter is:
'Void .ctor(Int32)


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

public class Example
{
    public Example() { }
    public Example(int i) { }

    public static void Demo(System.Windows.Controls.TextBlock outputBlock)
    {
        Type myType = typeof(Example);
        Type[] parameters = { typeof(int) };

        // Get the constructor that takes an integer as a parameter.
        ConstructorInfo ctor = myType.GetConstructor(parameters);

        if (ctor == null)
        {
            outputBlock.Text += 
                "There is no public constructor of MyClass that takes an integer as a parameter.\n";
        }
        else
        {
            outputBlock.Text += 
                "The public constructor of MyClass that takes an integer as a parameter is:\n"; 
            outputBlock.Text += ctor.ToString() + "\n";
        }
    }
}

/* This example produces the following output:

The public constructor of MyClass that takes an integer as a parameter is:
Void .ctor(Int32)
 */

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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