given the following class structures:[code]I add the following property to MyList, trying to answer questions like "find out the number of elements with specified type, say Derived1, inside MyList?"[code]
View 1 RepliesI have created a Dictionary class (MyDictionary for the example). I am currently trying to pass MyDictionary into a function, filter it into a new instance of MyDictionary and pass this new instance into another method. When I am attempting to create the second instance from the filtered first instance of MyDictionary via Lambda Expressions and the ToDictionary Method, I am getting the following error:
Unable to cast object of type 'System.Collections.Generic.Dictionary`2[System.Int32,System.String]' to type 'MyDictionary'. I have simplified the example and recreated it in LINQPad and am getting the same error.
Here's the simplified version of my code:
[Code]...
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)
crmService.InsertProspectGetId(sProgramInterest.ToList)
But I'm getting this error.
[code].....
And here is the code that produces the error
CODE:
How can i cast this one?
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())*
[Code].....
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]......
I have a series of API calls that are returning J# data types. I have been able to convert most of the data types (Integer, Boolean, Double, Float, etc) just fine.What I need to do now is convert a java.Util.Collection to a VB .NET collection (ArrayList)
Here is my attempt:
Public Function MakeDotNETCollection(ByVal javaCol As java.util.Collection) As Collection
Dim dotNetCol As Collection
[code]....
I keep getting a runtime error "Unable to cast object of type 'AbstractListlistIterator' to type 'System.Collections.IEnumerator.
This code:
vb Dim s As String = strContents '<a global variable) Dim currentPos As Int64 = 0 Dim endPos As Int64 = strContents.Length - 1 '// A dictionary, used to count the frequencies Dim characterCounter As New Dictionary(Of [String], Int64)() While currentPos <> endPos '//
[CODE]...
Gives this error: Value of type 'System.Collections.Generic.KeyValuePair(Of String, Long)' cannot be converted to 'System.Collections.DictionaryEntry'.
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'.
We have migrated our Vb6 application to VB.NET using a third party tool. Now we are in a process of Refactoring and introducing object oriented concepts in the application.
In VB6, we were using structures in many places. As a part of introducing object oriented programming,
1. is it a good idea of changing all Structures to Classes? or Is there a concept of "Generic Structure" similar to Generic collections, Generic classes?
2. Can some one guide me any source containing guide lines or best practices for applications that are migrated to VB.NET from VB6 and implementing object oriented programmaing.
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]'.
[Code]....
I have a generic Class I'm using to hold information loaded from a database.I have a method which takes a DataRow as an argument, uses the object's known column name and extracts the data from the DataRow, such that:Dim loadData As T = CType(myDataRow("myColumnName"), T))works as my default assignment in most cases.Unfortunately, due to some horrifying design constraints, some of my columns may be null, and may also be taken from enumerations.This means that when <T> is Nullable(Of SomeEnumeration) the above code does not work because I can't cast 0 directly to SomeEnumeration.Zero.Is there some way to check whether <T> is Nullable(Of [Enum])? Or some way to write a method which allows Integers to be cast to Nullable(Of [Enum])?I feel like I'm forgetting something that would allow me to write one of the other of these, but my weak google-fu is turning up nothing.
EDIT: Okay, thanks to dasblinkenlight's answer below, I can detect when this circumstance is occurring, but what I need to do now is to take a type <T> which I know is Nullable(Of SomeClass), get a type reference to SomeClass and then create a new object of type Nullable(Of SomeClass) and assign that to LoadData.My problem was that I had a lot of difficulty in finding any function which would accept baseType as an actual Type.Parse accepted baseType as a parameter, I knew baseType was an [Enum] type because of dasblinkenlight's code, so I was, in this instance, able to code a solution. It's a solution which is very specific to my problem (i.e., T is Nullable(of SomeEnumeration)), but it's a solution nonetheless.
[code]...
What's really the point in using the former?It's hard to use linq if I used the former. I have to convert that to an array first which is difficult because there is no (asarray) function.I think I would change all of my code that's using System.
Collections.Specialized.StringCollection to System.Collections.Generic.List(Of String)
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'.
[code]....
I have a parent class and many children class, right now it look like this:
Public Class Parent
Public Property ID as String
End Class
[Code].....
What I need is a strongly type list List(Of Child) that Inherits from ListOfParent (I need the FindByID method) but I can't find the right syntax.
Is there an exhaustive list of all of the "base" (not used in an object-oriented sense but more in a common sense) generic types in the 4.0 .NET Framework? I have found this list that I often send newer/mid-level devs to so they can understand how non-generic types map to generic types, but this is by no means exhaustive. I'm looking for something that also includes things such as KeyValuePair<>, Tuple<>, and other basic generics that may not be very-well known. Interfaces such as IObservable<> would be nice but not necessarily required.
View 6 RepliesI've hit a problem with the way I am using generics and I suspect that my design isn't quite right. I have a base class
AbstractBaseClass
inherited by
InheritingOneClass
[code]....
I have a generic list IList(of T as AbstractBaseClass) which I am populating with instances of the various inheriting classes. Now I can cycle through the list BUT depending on which subtype the item is, I want to pass the item to various functions (or instantiate various classes) which access properties/methods of the inheriting Class. I don't really want to have to use a Select Case and list all the potential types of the Inheriting classes. Is there a mechanism I can put in place to automate this?
I am new to VB.NET, just landed a job fresh out of school (well still in school), but I am having trouble with VB...alot of it is getting used to the IDE itsself (we use VB 2010).t does alot of the work for you which is cool but I am having some trouble understanding some concepts.Here are my questions: How to call classes named an initialized on a DSS skeleton to a new page. And the functionalities of building a collection. (also the differences of a generic
View 5 Repliesimagine i want to add an extension method to System.Collections.Generic.List(Of T)
let's say i want to give it .GetUBound which returns Count-1
I have a lists of different custom classes and each must be sorted severals times before the algorithm is complete. For each sort I wrote a comparer. Sofar so good. Everything works. But: By now I have abou a dozen different comparers in more than one class and it is still getting more. I wonder if there is a way to limit the number by writing a new general function that can be used to sort all lists without the need for a specific comparer.Below is what I've got so far. But it does not work.
"System.Collections.Generic.List(Of ClassA)" can not be converted into "System.Collections.Generic.List(Of Object)."
[code].....
If i wish to put items into a System.Collections.Generic.Dictionary, I can either Add or set the Item.I know if you do Add it helps you check if the key already exists and if not it throws an exception.Now I'm curious, so if I'm adding a ton of items, should I prefer setting Item instead of Add since Add does unnecessary checks that may actually slow things down?
View 3 RepliesI am trying to pass a System.Collections.Generic.List to another class. The collection is created in class2 and then passed into class1
[code]...
However I get a 'Null Reference Exception error' when I run the program. It seems f_str in the line 'For Each s As String In f_str' is null.
I am planning to use a List in my application but when I was searching for System.Collections.Generic, it only has System.Collections. I tried to look it up in the "add reference" and its not there.
View 2 Replieshow to find a value in the System.Collections.Generic.List.I have:
Private ids As New List(Of Byte())
ids.add(New Byte(){&HA8,&H0F})
ids.add(New Byte(){&HFF,&H03})
ids.add(New Byte(){&H10,&H00})
I would like to find for example: &H10,&H00 in that list and if there isn't the stuff I wan't to find then how do I know that?
I want to write a generic file saving routine where the routine is passed data in the form of a collection and it sets a containsStructure flag. I wanted to be able to save the data from the collection, but if it is a collection of structures I want to be able to extract the data from the structure to write to the file.
The only trouble is, that I cannot do something like:
For Each s As dataStructure In data
Next
Since the compiler complains that dataStructure is not defined. Is there a way to code around this?
in what situation will an item in System.Collections.Generic.List not be removed successfully?url...The way they phrase it makes me think that it is possible that a Remove operation on an item found in the List(Of T) could actually fail.
View 4 RepliesConsider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
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
[code]....
is giving me this error:'Feedback' must implement 'Function GetRuleViolations() As System.Collections.Generic.List(Of RuleViolation)' for interface 'iRuleEntity'.
I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
I am trying to create a list of a generic type in vb.net 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
[Code]....
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.