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StateManagedCollection.GetKnownTypes Method

When overridden in a derived class, gets an array of IStateManager types that the StateManagedCollection collection can contain.

Namespace: System.Web.UI
Assembly: System.Web (in system.web.dll)

protected virtual Type[] GetKnownTypes ()
protected Type[] GetKnownTypes ()
protected function GetKnownTypes () : Type[]
Not applicable.

Return Value

An ordered array of Type objects that identify the types of IStateManager objects the collection can contain. The default implementation returns a null reference (Nothing in Visual Basic).

The GetKnownTypes method is called internally by the StateManagedCollection collection in its implementation of the System.Web.UI.IStateManager.SaveViewState method. Derived collections override the GetKnownTypes method to return an array of Type objects that represent the types the collection can contain.

The following code example demonstrates how a strongly typed StateManagedCollection class implements the GetKnownTypes method. The CycleCollection implementation of GetKnownTypes returns a Type array of known types, including Bicycle and Tricycle types. This code example is part of a larger example provided for the StateManagedCollection class.

// The strongly typed CycleCollection class is a collection
// that contains Cycle class instances, which implement the
// IStateManager interface.
public sealed class CycleCollection : StateManagedCollection {
    private static readonly Type[] _typesOfCycles 
        = new Type[] { typeof(Bicycle), typeof(Tricycle) };

    protected override object CreateKnownType(int index) {
        switch(index) {
            case 0:
                return new Bicycle();
            case 1:
                return new Tricycle();                    
                throw new ArgumentOutOfRangeException("Unknown Type");

    protected override Type[] GetKnownTypes() {
        return _typesOfCycles;

    protected override void SetDirtyObject(object o) {


Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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