Type.FindInterfaces(TypeFilter, Object) Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

Type.Helpers.cs

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

public:
 virtual cli::array <Type ^> ^ FindInterfaces(System::Reflection::TypeFilter ^ filter, System::Object ^ filterCriteria);

public virtual Type[] FindInterfaces (System.Reflection.TypeFilter filter, object? filterCriteria);

abstract member FindInterfaces : System.Reflection.TypeFilter * obj -> Type[]
override this.FindInterfaces : System.Reflection.TypeFilter * obj -> Type[]

Public Overridable Function FindInterfaces (filter As TypeFilter, filterCriteria As Object) As Type()

Parameters

filter

TypeFilter

The delegate that compares the interfaces against filterCriteria.

filterCriteria

Object

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

Returns

Type[]

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

Exceptions

ArgumentNullException

filter is null.

TargetInvocationException

A static initializer is invoked and throws an exception.

Examples

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

#using <system.xml.dll>

using namespace System;
using namespace System::Xml;
using namespace System::Reflection;
public ref class MyFindInterfacesSample
{
public:
    static bool MyInterfaceFilter(Type^ typeObj, Object^ criteriaObj)
    {
        if(typeObj->ToString()->Equals(criteriaObj->ToString()))
            return true;
        else
            return false;
   }
};

int main()
{
    try
    {
        XmlDocument^ myXMLDoc = gcnew 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 = gcnew TypeFilter( 
            MyFindInterfacesSample::MyInterfaceFilter);
        array<String^>^myInterfaceList = {"System.Collections.IEnumerable",
            "System.Collections.ICollection"};
        for(int index = 0; index < myInterfaceList->Length; index++)
        {
            array<Type^>^myInterfaces = myType->FindInterfaces( 
                myFilter, myInterfaceList[index]);
            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}.",
                    myInterfaces[j]);
            }
            else
                Console::WriteLine(
                    "\n{0} does not implement the interface {1}.", 
                    myType, myInterfaceList[index]);

        }
    }
    catch(ArgumentNullException^ e) 
    {
        Console::WriteLine("ArgumentNullException: {0}", e->Message);
    }
    catch(TargetInvocationException^ e) 
    {
        Console::WriteLine("TargetInvocationException: {0}", e->Message);
    }
    catch(Exception^ e) 
    {
        Console::WriteLine("Exception: {0}", e->Message);
    }
}

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

public class MyFindInterfacesSample
{
    public static void Main()
    {
        try
        {
            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]
                {"System.Collections.IEnumerable",
                "System.Collections.ICollection"};
            for(int index=0; index < myInterfaceList.Length; index++)
            {
                Type[] myInterfaces = myType.FindInterfaces(myFilter,
                    myInterfaceList[index]);
                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}.",
                            myInterfaces[j].ToString());
                }
                else
                    Console.WriteLine(
                        "\n{0} does not implement the interface {1}.",
                        myType,myInterfaceList[index]);	
            }
        }
        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;
        else
            return false;
    }
}

open System
open System.Xml
open System.Reflection

let myInterfaceFilter (typeObj: Type) (criteriaObj: obj) =
    string typeObj = string criteriaObj

try
    let myXMLDoc = XmlDocument()
    myXMLDoc.LoadXml("<book genre='novel' ISBN='1-861001-57-5'>" + "<title>Pride And Prejudice</title>" + "</book>")
    let myType = myXMLDoc.GetType()

    // Specify the TypeFilter delegate that compares the
    // interfaces against filter criteria.
    let myFilter = TypeFilter myInterfaceFilter
    let myInterfaceList =
        [ "System.Collections.IEnumerable"
          "System.Collections.ICollection" ]
    for i in myInterfaceList do
        let myInterfaces = myType.FindInterfaces(myFilter, i)
        if myInterfaces.Length > 0 then
            printfn $"\n{myType} implements the interface {i}."
            for j in myInterfaces do
                printfn $"Interfaces supported: {j}."
        else
            printfn $"\n{myType} does not implement the interface {i}."
with
| :? ArgumentNullException as e ->
    printfn $"ArgumentNullException: {e.Message}"
| :? TargetInvocationException as e ->
    printfn $"TargetInvocationException: {e.Message}"
| e ->
    printfn $"Exception: {e.Message}"

Imports System.Xml
Imports System.Reflection

Public Class MyFindInterfacesSample
    Public Shared Sub Main()
        Try
            Dim myXMLDoc As New XmlDocument()
            myXMLDoc.LoadXml("<book genre='novel' ISBN='1-861001-57-5'>" _
                & "<title>Pride And Prejudice</title>" & "</book>")
            Dim myType As Type = myXMLDoc.GetType()

            ' Specify the TypeFilter delegate that compares the 
            ' interfaces against filter criteria.
            Dim myFilter As New TypeFilter(AddressOf MyInterfaceFilter)
            Dim myInterfaceList() As String = _
                {"System.Collections.IEnumerable", _
                "System.Collections.ICollection"}
            Dim index As Integer
            For index = 0 To myInterfaceList.Length - 1
                Dim myInterfaces As Type() = _
                    myType.FindInterfaces(myFilter, myInterfaceList(index))
                If myInterfaces.Length > 0 Then
                    Console.WriteLine(ControlChars.Cr & _
                        "{0} implements the interface {1}.", _
                        myType, myInterfaceList(index))
                    Dim j As Integer
                    For j = 0 To myInterfaces.Length - 1
                        Console.WriteLine("Interfaces supported: {0}", _
                            myInterfaces(j).ToString())
                    Next j
                Else
                    Console.WriteLine(ControlChars.Cr & _
                        "{0} does not implement the interface {1}.", _
                        myType, myInterfaceList(index))
                End If
            Next index
        Catch e As ArgumentNullException
            Console.WriteLine("ArgumentNullException: " & e.Message)
        Catch e As TargetInvocationException
            Console.WriteLine("TargetInvocationException: " & e.Message)
        Catch e As Exception
            Console.WriteLine("Exception: " & e.Message)
        End Try
    End Sub
    Public Shared Function MyInterfaceFilter(ByVal typeObj As Type, _
        ByVal criteriaObj As [Object]) As Boolean
        If typeObj.ToString() = criteriaObj.ToString() Then
            Return True
        Else
            Return False
        End If
    End Function 'MyInterfaceFilter 
End Class

Remarks

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.

Note

FindInterfaces can 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).

See also

• Module
• TypeFilter
• GetInterface(String)
• GetInterfaces()