Generic TypeOf Operator - See If List Is A List(Of T) Variable - Error: "Type Expected"?

Jan 5, 2011

Dim x = GetType(List(Of )) 'valid statement
Dim list As New List(Of String)

Now I want to see if list is a List(Of T) variable: Dim isList = TypeOf list Is List(Of ) On the last line I get a compile error: "Type Expected". Is there any cheap-performance TypeOf operator alternative for generics?


Error - Red "List" Says Too Few Type Arguments To System.Collections.Generic.List(Of T)'

Mar 12, 2009

I have converted c# .cs to vb:= I have 6 errors on:

Red "List" says Too few type arguments to system.Collections.Generic.List(Of T)'
Orange "Calendar" says Value of type 'System.Windows.Forms.Control.ControlCollection' cannot be converted to 'Form1.Kobush.Windows.Forms.Appointment'.


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Get Type Of Derived Generic List Class From List Item Method?

Mar 23, 2011

Public Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()


When I debug this winforms application I get curType = "notifier.notifierMain+Contacts+row" I want to the Validate function to know it is in MyContacts. How do I do this?

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Can't Find The .net Equivalent Of A Variable Type Of A "raw" Generic List That Takes A Wild Card?

May 17, 2012

I'm strictly looking for a language conversion here of this:List<?> I already have a work around I'm just surprised that I can't find the equivalent of a variable type of a "raw" generic list that takes a wild card.Java's mechanism here enables you to reference a list regardless of what T is.Java even enables you to go further and do things like:

List<? extends Number>
List<? super Double>I tried:
List(Of )

and that did not work. That only seems to work inside the GetType function.

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.net - ByRef Underlined With "Expression Expected" Error When Trying To Pass In A Object Of Type List(Of ClsFooDetail)?

Mar 3, 2010

I work with C# 99% of the time. However, I'm having to update some legacy VB.Net code and encountering an issue with VB.Net code syntax. The error that I get is "ByRef" is underlined and "Expected Expression" tag shows up when you hover over "ByRef". The "FooDetail.Load" function is written in C# and expects a List object passed as reference. Don't have any trouble using the same function in other C# classes. Can someone indicate what is wrong with below VB.Net code.

Dim FooDetail As New clsFooDetail()
FooDetail.FooID = FooID
Dim lstFooDetail As New List(Of clsFooDetail)
FooDetail.Load(ConnectionString, "Stored Procedure", ByRef lstFooDetail as System.Collection.List(Of(clsFooDetail))

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.net - Creating A Generic List Of A Generic Type

Jun 30, 2011

I am trying to create a list of a generic type in 2.0 framework.
This is the generic type definition:

Public Class GenericParamMap(Of T)
Public Sub New(ByVal pParamName As String, ByVal pPropValue As T)
mParamName = pParamName


The compiler does not allow a "T" in the method's parameter because it's not defined, but I'm not sure how or where to define it. I thought it was okay to have a generic method definition.

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Unable To Cast Object Of Type .objectquery To Type Generic.list

Sep 12, 2011

I have a question about ASP.Net, visual basic I have 2 LINQ query's, the first one works, the second one doesnt, produces a

"Unable to cast object of type 'System.Data.Objects.ObjectQuery'1[SelmaV2.Products]' to type 'System.Collections.Generic.List'1[System.String]'.


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Creating A Generic List Of A Specified Type?

May 26, 2010

I want to create a generic list - but I want to specify the type at runtime - is there a way I can do this? using reflection perhaps?Something like this...

Public Shared Sub create(ByVal t As Type)
Dim myList As New Generic.List(Of t)
End Sub

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Difficulties Sending A Type To A Generic List?

Nov 23, 2011

I'm trying to use a generic list without knowing the type when loading the page. I have a typePropertyCollection which inherits from List(Of PropertyData). The usercontrol that uses this collection doesn't know what type of data is used (which objects). So when the page is loaded, I pass along the type to the usercontrol using a dependencyproperty. This type ends up in this method:

Private Shared Sub OnObjectTypeChanged(ByVal obj As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
Dim objectType As Type = TryCast(args.NewValue, Type)


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Generic Function For List Type Filter?

Jan 13, 2011

I would like to write a generic function that would search a List(Of T) for all elements of type TFilter and return a List(Of TFilter) which comprises those elements.

I've tried this:
Public Function FilterList(Of T, TFilter)(ByVal ListToFilter As List(Of T)) As List(Of TFilter)
Return ListToFilter.FindAll(Function(z) z.GetType.Equals(GetType(TFilter))).ConvertAll(New Converter(Of T, TFilter)(Function(z) CType(z, TFilter)))
End Function

But, it gives the following error:
Value of type 'T' cannot be converted to 'TFilter'.

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Create A List Of A Generic Type That Will Be Passed As A Parameter?

Feb 14, 2011

say I have two POCOs I'm using in EF code first

Public class C1
property F1 as integer
End Class
Public class C2
property F2 as String
End Class

I want to have a function that will create a list either of C1 or C2, to be used in some generic operation, such that


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.net - Test If Property Of Type System.Collections.Generic.List(of T)?

Apr 10, 2012

I need to be able to tell if a property is of type List(of T)but am currently unable to. if i do

TypeOf (UpdateTo.GetType.GetProperty(node.Name)) Is System.Collections.Generic.List(Of Object)

I get the following error

TypeOf (UpdateTo.GetType.GetProperty(node.Name)) Is
System.Collections.Generic.List(Of Object) Expression of type
'System.Reflection.PropertyInfo' can never be of type[code]......

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Unable To Cast Object Of Type 'System.Collections.Generic.List`1[System.Int32]' To Type 'crmWebService.ArrayOfInt'?

May 14, 2012

I'm getting an error after sending a list to a web service.This is the code that is calling the web service:

Dim sProgramInterest As New List(Of Integer)
But I'm getting this error.


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Determine If Property Is Generic List<of T> Via Reflection And Loop List Items

Oct 1, 2009

I'm looping all the properties in an object via reflection:

For Each p As PropertyInfo In values.[GetType]().GetProperties()
If p.CanRead Then
'Do stuff
End If

how to determine whether the property in question is a generic List(Of T)? If it is I need to loop the list itself.

I've experimented with GetType and TypeOf but have not managed to get anything working.

To clarify, I want to keep this generic. I do not want to specify the type of T, I need to loop the list items and call the ToString method on each item. T could be one of a number of different types (application specific reference types). Is it possible to do this without specifying types?

(VB.NET 2005 with .Net 2.0)

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.net - Returning A List Using Entity Framework, 'System.Collections.Generic.List Cannot Be Converted To '1-dimensional Array

May 3, 2012

i have issue returning a list in a web method. here is the code

<WebMethod()> _
Public Function getTags(para_parents As String) As List(Of getTypeDetailsByParentName_Result)()
Dim context As New PPEntities


the error is

Value of type 'System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)' cannot be converted to '1-dimensional array of System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)'

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Pass Generic List To A Function That Has A Custom Defined List

Apr 7, 2011

it seems always at this time I cant figure out how to do something maybe it has something to do with lunchtime.

Im having trouble using a method that is defined by an outside company

This is a link to their integration guide:


This is their documentation for the class Im trying to use

OrderQueryWebService Class

This class is for SID in particular and is made for use with the notification methods. This is for the Order Query Web Service specifically, allowing clients to return the status of transactions for their merchant, whenever they want to.

/ <summary>
/ Pass through the variables required and receive a list of Transaction
objects showing transaction status


The MerchantCode, the MerchantUsername, the MerchantPassword are all good the List is a custom type called SetComHash.Transaction

Everytime I try adding a string to the list such as the transactionNumber and some other values it gives me a type error:

"Value of type string cannot be converted to 'SetcomHash.Transaction'

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.net - Sort Generic List Based Upon A Different List?

Oct 29, 2010

What would be the fastest way to sort a list that contains a list of objects, based upon another list? An example follows:Say I have multiple lists of employees. Each individual list has a common property value, say "Department". So I have a list of employees, in one list they all have the department string value of "Sales". In another list all the objects have a department value of "Finance". These lists of employees are then contained in a list which holds them all.

I have a second list, which should drives the sort order of the employee lists. The second list simply contains a list of strings like, "Finance", "Sales", "IT" and so on. I'd like my lists of customers to be sorted in the order of "Finance", "Sales", etc.I'm using VB.NET in .NET 2.0

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Error:'Feedback' Must Implement 'Function GetRuleViolations() As System.Collections.Generic.List

Mar 20, 2009

I need another (dozen) pair of eyes on this. The following code:

Interface iRuleEntity
Function GetRuleViolations() As List(Of RuleViolation)
End Interface
Partial Public Class Feedback


is giving me this error:'Feedback' must implement 'Function GetRuleViolations() As System.Collections.Generic.List(Of RuleViolation)' for interface 'iRuleEntity'.

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VS 2010 Custom Type Array / List With Adding Items And Specifying Custom Type Variable

Jun 21, 2011

I recently downloaded VB 2010 Express so i am quite new to the language, but i have worked with dark basic, which seems to b very similar.Anyway, my problem is that i cannot seem to correctly set out my array of a custom type/class. i am trying to create two arrays, one of available entities and another of selected entities of which the user selects the entities to be dealt with in irrelevant ways. i have creates a button (called test) which adds some entities to the available list and all the entities come back the same value but they shouldnt be as you'll c in the code. i have run the step into command a found that "available.item(#).Name = " will change all of the entity's names.As of current i am working with lists as the array kept asking for a 'new' statement but i couldnt figure out where to put it.[code]

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VS 2008 Will Not Need To Update Each Component Variable Of Products List When Components List Changes

Sep 21, 2010

I think (?) this is about object design, and perhaps about structural and/or creational patterns. But a bit hard to say when I only know a couple of patterns yet.[code]But... what if we INSTEAD want each Product instance only to (in some way) refer to one instance of a specific list of Components. So we wan't to save the products list to one file, and the components list to another file. Then would I build the objects the same way, or different? So let's then say we have now Class B as below. [code]

1. Will not need to update each component variable of the products list when the components list changes.

2. If the Product object shall be shown in a DataGridView, for editing properties, it seems easier to implement the selection of the component property.

Is this wrong approach? Is it suitable in some cases, and if so, when? Are there other solutions I perhaps am not aware of that would be appropriate? Is this about structural design patterns? and if so, can the alternatives above be catagorized to some pattern type? I don't really know exactly what I'm looking for.. But I think probably I'm looking to understand whether the object design will be determined by the way the objects are saved.. And if i shall save the objects by serializing to file, vs saving to a database, would I create the business objects differently?

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VS 2008 Declare A List(of T) (or List(of <anonymous Type>))?

Jan 7, 2010

Ok i'm trying to declare a global list of type T (or is it <anonymous type>) i declare it in a module with something like Friend query As New List(of {whatever type i try}) the app takes some xml and parses it into a list but i need this list available to other classes and methods within the app, everything i have tried fails resulting in an error like Value of type 'System.Collections.Generic.List(Of <anonymous type>)' cannot be converted to 'System.Collections.Generic.List(Of {whatever type i try})'.

What would be the correct way to declare a list of this type? is there another way i could do this?

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Error: Option Strict On Disallows Operands Of Type Object For Operator '='. Use The 'Is' Operator To Test For Object Identity

Jan 27, 2010

I am tightening up my coding with the Option Strict set to ON. It has now produced alot of errors. An example of this is:

If AllocatedDGV.Rows(i).Cells("RoomNumber").Value = RoomsAvailableDGV.Rows(j).Cells("RoomName").Value Then

It gives me the following error: Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity.

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VS 2005 List(of T) - Create A List To Hold More Than One Control Type Or Create A List For Each Control Type?

Jan 20, 2011

If I create a list for a TextBox:


I am able to only add controls that are of type TextBox. My question to you is, can I create a List to hold more than one control type or do I have to create a list for each control type?

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Operator '=' Is Not Defined ... For A Variable And Object Of THE SAME TYPE?

May 5, 2011

Okay, I am TOTALLY confused here. I have a class... say MyClass. It has several properties of another class of my type, say MyHelperClass (along with other properties).

I am doing the following:
Dim inst As MyClass = New MyClass() With {
.p1 = sv1,


View 2 Replies View Related - Value Of Type 'System.Collections.ArrayList' Cannot Be Converted To 'System.Collections.Generic.List(Of ITextSharp.text.IElement)'

Sep 21, 2011

I'm having a problem with this code in the highlighted line(*); getting the error in the heading.

Dim htmlarraylist As New List(Of iTextSharp.text.IElement)
htmlarraylist = *HTMLWorker.ParseToList(New StreamReader(tempFile), New StyleSheet())*


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Error: Operator '=' Is Not Defined For Type 'FileInfo' And Type 'Boolean'

Aug 19, 2010

This is my


This is my error: Operator '=' is not defined for type 'FileInfo' and type 'Boolean'.

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C# - WCF Serialization And Interfaces - Error: List(of Object) Cannot Be Converted To List(of IMyInterface)

Oct 16, 2009

Does link text mean I have to return a concrete implementation? Even though I am using svcutil with the /r that includes my entites(where IMyInterface is defined). I get no errors but it changes all List(of IMyInterface) to list(of Object) and I cannot deserialize it on the client

Error: list(of object) cannot be converted to list(of IMyInterface).

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VS 2010 List(of Class) - System.NullReferenceException Error When Add The Info To The List

Jan 27, 2011

I'm getting System.NullReferenceException error when I try to add the employee info to the Employees list.


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Deleting A File Using A Checked List Box - Error: Unable To Cast Object Of Type

Jun 21, 2010

I am trying to delete a file(s) from a checked list box, when i click a button.

This is the code i have:

Dim item As IO.FileInfo
For Each item In CheckedListBox1.CheckedItems
Catch : End Try
Next item

But i get the error: Unable to cast object of type 'System.String' to type 'System.IO.FileInfo'.

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Getting Error: Type Expected?

Apr 9, 2010

Everywhere text is in Black i get the error "Type Expected"

Private Sub Done(ByVal sender As Object, ByVal e As Windows.Forms.WebBrowserDocumentCompletedEventArgs)
TabControl1.SelectedTab.Text = CType(TabControl1.SelectedTab.Controls.Item(0),


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Using List(Of T).ForEach Method To Update Values Not Working As Expected?

Aug 8, 2011

I have the following code,

PB.ForEach(Function(x) x.Cost = GetPartCost(x.PartNumber, x.Units, x.Cost, FB))

Return PB.Sum(Function(x) (x.Cost * x.Qty))

However it always returns 0. I've checked and the GetPartCost function executes and returns a non-zero number but the list item cost properties are never updated.The property is just a simple property,

Public Property Cost() As Double
Return _Cost[code]....

If I set a breakpoint in the Set of the property, it never gets hit.

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C# - .NET Generic Class Instance - Passing A Variable Data Type

Jun 2, 2010

I'm tyring to pass a variable data type to a template class. Something like this:

frmExample = New LookupForm(Of Models.MyClass) 'Works fine

Dim SelectedType As Type = InstanceOfMyClass.GetType() 'Works fine
frmExample = New LookupForm(Of SelectedType) 'Ba-bow!
frmExample = New LookupForm(Of InstanceOfMyClass.GetType()) 'Ba-bow!


I'm assuming it's something to do with the template being processed at compile time but even if I'm off the mark there, it wouldn't solve my problem anyway. I can't find any relevant information on using Reflection to instance template classes either.

(How) can I create an instance of a dynamically typed repository at runtime?

View 4 Replies View Related - Find The Max Id From A Generic List?

Oct 13, 2011

i m getting a collection of data in list's object. And from this list i want to get the maximum id.`

Dim objinfo As List(Of AlbumInfo) = objPhotos.GetPhotos_Alb_ID(Me.ModuleId, hdd_AlbID.Value)
Dim Photo_Image As String = ""
Dim str As String = Photo_Image & fu_Photo.PostedFile.FileName.Substrng(fu_Photo.PostedFile.FileName.LastIndexOf("."))


this returns the "0"th positions id from Convert.ToString(objinfo.Item("0").Photo_Id + 1)but i want to get the last item's id.

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C# - Sum Of A Column Of Generic List?

Jan 5, 2011

i have list of string like this :

Dim totalPrice As New List(Of Integer)

how can i get sum of column(0) (C# or VB) ?

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Generic List, Add, And Same Values?

Jan 17, 2011

<div class=PhorumReadBodyText>Hi, I have a problem with adding of items to generic list, problem is when I insert 1. item to the list, everithing is ok, but if I insert second item, first and second has same values. 

code looks like that ( 4.0): </div> <div class=PhorumReadBodyText> </div> <div class=PhorumReadBodyText>Partial Class _Default
Inherits System.Web.UI.Page


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How To Add Items To Generic List

Jan 17, 2011

I have a problem with adding items to generic list, problem is when I add 1. item to the list, everything is ok, but when I add second, first and second has the same values...

This is code ( 4.0):
Partial Class _Default
Inherits System.Web.UI.Page
Public Class Product
Shared Property Material As String

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Loop Through Generic List

Aug 26, 2009

In my application I am populating my customer object and looping through it as shown below.As there are thousands of customers, I want to do it 500 customers at a time.Is there anyway I can have one more For loop to process 500 customers at one shot in vB.netI am not using LinQ as the database is Oracle.[code]

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Looping Through Generic List?

Apr 30, 2010

I want my loop to loop until it reaches the last string in my generic list. I know I could simply insert the last index of the list as an integer but I want to be able to use this if my list grows too. How could I achieve this?

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Searching A Generic List

May 14, 2009

I have been reading extensively about searching generic lists in VB.NET with the usage of delegates.However, I still cannot seem to grasp how to achieve what I want to, which I believe is frustratingly simple! I have a list populated with instances of an object with three parameters (fields/ variables).When I receive a new object to add to the list I want to search the list for the "layer" field.If the field matches then I will replace that row (object) in the list with the new object, if no match is found then I will add it to the list. [code]

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Splitting A Generic List?

Jun 11, 2011

i have a generic list of type datarow.i have to split this list at an index and then use both parts of the list.

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