Type.FindInterfaces Method (TypeFilter, Object)


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Returns an array of Type objects representing a filtered list of interfaces implemented or inherited by the current Type.

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

public virtual Type[] FindInterfaces(
	TypeFilter filter,
	object filterCriteria


Type: System.Reflection.TypeFilter

The delegate that compares the interfaces against filterCriteria.

Type: System.Object

The search criteria that determines whether an interface should be included in the returned array.

Return Value

Type: System.Type[]

An array of Type objects representing a filtered list of the interfaces implemented or inherited by the current Type, or an empty array of type Type if no interfaces matching the filter are implemented or inherited by the current Type.

Exception Condition

filter is null.


A static initializer is invoked and throws an exception.

This method can be overridden by a derived class.

The Module.FilterTypeName and Module.FilterTypeNameIgnoreCase delegates supplied by the System.Reflection.Module class may also be used, in lieu of the System.Reflection.TypeFilter delegate.

All of the interfaces implemented by this class are considered during the search, whether declared by a base class or this class itself.

This method searches the base class hierarchy, returning each of the matching interfaces each class implements as well as all the matching interfaces each of those interfaces implements (that is, the transitive closure of the matching interfaces is returned). No duplicate interfaces are returned.

If the current Type represents a type parameter in the definition of a generic type or generic method, FindInterfaces searches all the interfaces declared in the constraints on the type parameter, and all interfaces inherited through the interfaces declared in the constraints. If the current Type represents a type argument of a generic type, FindInterfaces searches all the interfaces implemented by the type, whether or not they match constraints.


FindInterfacescan return generic interfaces, even on types that are not generic. For example, a nongeneric type might implement IEnumerable<int> (IEnumerable(Of Integer) in Visual Basic).

The following example finds the specified interface implemented or inherited by the specified type, and then displays the interface names.

using System;
using System.Xml;
using System.Reflection;

public class MyFindInterfacesSample 
    public static void Main()
            XmlDocument myXMLDoc = new XmlDocument();
            myXMLDoc.LoadXml("<book genre='novel' ISBN='1-861001-57-5'>" +
                "<title>Pride And Prejudice</title>" + "</book>");
            Type myType = myXMLDoc.GetType();

            // Specify the TypeFilter delegate that compares the 
            // interfaces against filter criteria.
            TypeFilter myFilter = new TypeFilter(MyInterfaceFilter);
            String[] myInterfaceList = new String[2] 
            for(int index=0; index < myInterfaceList.Length; index++)
                Type[] myInterfaces = myType.FindInterfaces(myFilter, 
                if (myInterfaces.Length > 0) 
                    Console.WriteLine("\n{0} implements the interface {1}.",
                        myType, myInterfaceList[index]);	
                    for(int j =0;j < myInterfaces.Length;j++)
                        Console.WriteLine("Interfaces supported: {0}.", 
                        "\n{0} does not implement the interface {1}.", 
        catch(ArgumentNullException e)
            Console.WriteLine("ArgumentNullException: " + e.Message);
        catch(TargetInvocationException e)
            Console.WriteLine("TargetInvocationException: " + e.Message);
        catch(Exception e)
            Console.WriteLine("Exception: " + e.Message);

    public static bool MyInterfaceFilter(Type typeObj,Object criteriaObj)
        if(typeObj.ToString() == criteriaObj.ToString())
            return true;
            return false;

.NET Framework
Available since 1.1
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