Public Class CustomTextControl
    Inherits System.Web.UI.Control
    Implements System.Web.UI.ITextControl

    Private _text As String

    Public Property Text() As String Implements System.Web.UI.ITextControl.Text
        Get
            Return _text
        End Get
        Set(ByVal value As String)
            If (value <> Nothing) Then
                _text = value
            Else
                _text = "No Value."
            End If
        End Set
    End Property

    ' Provide the remaining code to implement a text control.
End Class

public class CustomTextControl : Control, ITextControl
{
    private string _text;

    public CustomTextControl()
    {
    }

    public string Text
    {
        get
        {
            return _text;
        }
        set
        {
            if (value != null)
            {
                _text = value;
            }
            else
            {
                _text = "No Value.";
            }
        }
    }

    // Provide the remaining code to implement a text control.
}