How Do I loop through this class once I have added items - vb.net

Question

How do i loop through this class once I add items via this method. Just I am quite new to generic lists so was wonding if someone could point me in right direction in datatables im used to doing the following:
For Each thisentry In dt.rows
Next
What do I use in collections
Calling Code
Calling this in my delciarations of main class
Dim infoNoProductAvail As List(Of infoProductsNotFound) = New List(Of infoProductsNotFound)()
this is how i am adding the files but I have checked in the routine and the count for the list is at 2 products
If medProductInfo.SKU.SKUID = 0 Then
infoNoProductAvail.Add(New infoProductsNotFound(thisenty2.Item("EAN13").ToString(), True))
End If
this is the class itselfs
Public Class infoProductsNotFound
Public Sub New(tbcode As String, notfound As Boolean)
Me.tagbarcode = tbcode
Me.notfound = notfound
End Sub
Private tagbarcode As String = String.Empty
Private notfound As Boolean
Public Property tbcode() As String
Get
Return tagbarcode
End Get
Set(ByVal value As String)
tagbarcode = value
End Set
End Property
Public Property isNotFound() As Boolean
Get
Return notfound
End Get
Set(ByVal value As Boolean)
notfound = value
End Set
End Property
End Class
Tried
I tried using the following
Function BuildExceptionsForEmail()
Dim retval As String = ""
Dim cnt As Int32 = 0
retval = "The following products are not avialable" & vbCrLf
For Each info As infoProductsNotFound In infoNoProductAvail
retval &= info.tbcode
cnt &= 1
Next
Return retval
but for some reason at this point my info noproductAvail is blank even though in the routine above its sitting at count of 2 what gives?

Answer 1

First I'd shrink that declaration a bit:
Dim infoNoProductAvail As New List(Of infoProductsNotFound)
Next, to iterate there are several options. First (and what you're likely most used to):
For Each info as infoProductsNotFound in infoNoProductAvail
If info.tbCode = "xyz" Then
DoSomething(info)
End If
Next
Or you might want to use lambda expressions (if you're using .Net 3.5 and above I think - might be .Net 4):
infoNoProductAvail.ForEach (Function(item) DoSomething(item))
Remember that generics are strongly typed (unlike the old VB collections) so no need to cast whatever comes out: you can access properties and methods directly.
If infoNoProductAvail(3).isNotFound Then
'Do something
End If
(Not that that is a great example, but you get the idea).

Answer 2

The For Each syntax is the same. It works the same way for all IEnumerable objects. The only "trick" to it is to make sure that your iterator variable is of the correct type, and also to make sure that you are iterating through the correct object.
In the case of the DataTable, you are iterating over it's Rows property. That property is an IEnumerable object containing a list of DataRow objects. Therefore, to iterate through it with For Each, you must use an iterator variable of type DataRow (or one of its base classes, such as Object).
To iterate through a generic List(Of T), the IEnumerable object is the List object itself. You don't need to go to one of it's properties. The type of the iterator needs to match the type of the items in the list:
For Each i As infoProductsNotFound In infoNoProductAvail
' ...
Next
Or:
Dim i As infoProductsNotFound
For Each i In infoNoProductAvail
' ...
Next
Or:
For Each i As Object In infoNoProductAvail
' ...
Next
Etc.