.net - Comparing Two Generic Lists On A Specific Property?
Jul 9, 2010
I'm using VB.NET with .NET 2.0. I have two lists, and I want to compare the lists on a specific property in the object, not the object as a whole, and create a new list that contains objects that are in one list, but not the other.
myList1.Add(New Customer(1,"John","Doe")
myList1.Add(New Customer(2,"Jane","Doe")
myList2.Add(New Customer(1,"","")
Result in the above example would contain one customer, Jane Doe, because the identifier 2 wasn't in the second list.How can you compare these two List<T> or any IEnumerable<T> in .NET 2.0 (lacking LINQ)?
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Dec 17, 2009
I'm creating <!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-
[code].....
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Sep 19, 2010
I accept both C# and VB.NET suggestion, even though I'm writing an app in VB.NET I have two lists of intergers
List1 {1,2,3,5}
List2 {2,4,6,7}
I want to have new List3 {4,6,7} which is composed of elements of List2 that are not in List1. I know I can write a nice For Each loop for this but I want it done in LINQ I've been looking for such methods at Enumerable Methods, but I can't find it.
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Apr 26, 2011
I have two array list same size, depending on the information gathered by previous functions. The size of the arrays range from 2 - 45 in length, both arrays always have the same length. I am trying to match one string in one array to another string in the second array. When they match then add Item to List.
Here is my
Do Until i = Arraylenght
info = Replace(myAL(s), " ", "")
SortedArrayList(m) = Replace(SortedArrayList(m), " ", "")
SortedLine = Split(SortedArrayList(m), "Price=")
If myAL(s).Contains(SortedLine(1)) Then
[Code] .....
This code works up to an array of not more then 4 in lenght, when working larger size array then 4, the minute it get to 5 I get this Error:
Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index
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Dec 20, 2009
I have two lists of strings. One is a list of all students in a class and the other is a list of students in the class that completed an assignment. The two lists are part:whole. So we have two loops for copying elements and displaying them in a list box for only the students who did submit.
Dim f As Integer
f = 0
Dim h As Integer
h = 0
While (usersinclass.Count > f)
h = 0
While (usersidthatsubmittedassingments.Count > h)
[Code] .....
What I need is the remaining portion of the "usersinclass" list. (i.e. The students who did not submit). I tried an Else statement BUT with nested loops, every element is guaranteed not to match at least once, so I was getting elements that shouldn't be there. So, is there anyway to run the given lists against each other again to pull out the remaining students? (preferably with no repeats).
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Mar 2, 2011
I have a method where I'm taking a generic object and using TypeOf to check what has been passed through. Now I would like to pass it a List(Of T) (T being anything) and no matter what T is I'd like to do the same thing to this list. I tried the following:
public sub foo(ByVal obj As Object)
if TypeOf obj Is List(Of Object) Then
'do stuff
end if
end sub
but this doesn't seem to work if I pass it List(Of String), say. I suppose that List(Of Object) and List(Of String) are being treated as different objects, but I thought that since String is an object, the comparision might work.
Now I realise that this is as ugly as sin and I'm better off overloading the method to take List(Of T) as its parameter, but I'm mostly asking out of curiosity: is there a way of comparing the types List(Of Object1) and List(Of Object2) and getting a positive result, since they are both just List(Of T)?
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May 6, 2009
I have a utility class that takes a generic list as a parameter.Code looks like:
Function DoStuff(collection as Object, elt as Object)
...
collection.Add(elt)
[code]....
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Sep 14, 2009
I have recently moved from VB 2003 to VB 2005. While I am finding a lot of the new features quite useful, I am having trouble with List (of T). I want to be able to do something like this
Function GetList(MyObjectType as Type) as datatable
Dim list as new List(of MyObjectType)
End Function
Function GetList(MyObjectType as String) as datatable
Dim list as new List(of GetType(MyObjectType))
End Function
VB 2005 does not allow me to do this at all. Must the "type of" be srongly declared at all times? Can't this be done dynamically?
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Mar 8, 2010
I was developing a small function when trying to run an enumerator across a list and then carry out some action. (Below is an idea of what I was trying to do. When trying to remove I got a "Collection cannot be modified" which after I had actually woken up I realised that tempList must have just been assigned myLists reference rather than a copy of myLists. After that I tried to find a way to say
[Code]...
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Jun 5, 2011
I am developing a subject plotter program for enrollment (but not an enrollment system), I use a database to store retrieve/store and update data. What my problem is that I have 2 listview, one that holds the chosen subject, and the other display's the offered subjects. How can I compare a specific item in the listview from another?
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Dec 8, 2009
I'd like to do something like this:
Private _myCollection As IList(Of T)
Public Property MyProperty(Of T)() as IList(Of T)
Get
[Code]....
Basically, I want to have a collection of items that may be of any type. Then, I'll be able to do something like this:
Dim myPropertyValue as <the type of some value>
if (MyProperty.Contains(<some value>))
myPropertyValue = CType(MyProperty(<some value>), <the type of some value>)
How can I do this? Or is there a better way than using a generic type?
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Mar 8, 2011
I'm attempting the following:Default Public Property Data(Of dataType)(ByVal key As String) As dataType
Get
Return DirectCast(values.Item(key), dataType)
End Get
Set(ByVal value As dataType)
values.Item(key) = value
End Set
End Property
[Code]...
It made more sense to make it a property, and it would be the default property of the class. The data type can not be specified on instantiation of the class, because it can contain multiple objects of different data types.
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Oct 15, 2009
I'm attempting the following:
Default Public Property Data(Of dataType)(ByVal key As String) As dataType
Get
Return DirectCast(values.Item(key), dataType)
[code].....
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May 29, 2010
I have a routine that accepts a List of Objects, a property name and a value to search for and simply returns whether or not it found it.The code I have hangs up at the For loop in the findit routine.[code]
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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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Jun 19, 2009
I have several custom classes in a VB.NET (VS2008) project which are related to each other through generic list collections. The lower tier classes refer directly to some of the parent classes (to make it easier to refer backwards up the chain). My question is, is it possible to add the reference to the parent class when the item is added to a collection, when that collection is a property?
Below is some sampling of code to illustrate.
Public Class FlexServer
Private m_FlexLicenses As List(Of FlexLicense)
Private m_Modules As List(Of FlexModule)
Public Property FlexLicenses() As List(Of FlexLicense)
[code] .....
In the code above I have the FlexServer class which refers has two lists as properties, one for FlexLicense and one for Modules. The FlexLicense class has a property to refer back to the FlexServer class that "owns" it. In order to update this property in code, I have to add the FlexLicense to the FlexServer.FlexLicenses list AND set the FlexLicense.FlexServer property. What I am looking for is, is there a way (in the property definition or wherever) to both add the item to the list and alter it at the same time?
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Apr 1, 2011
I have two lists. One list is a list of names, the other list is a list of how many times each name is found in the first list noted in the database
so...
Nick
John
Jim
Jack
is the firs tlist
10
13
13
2
is the second list. Nick had 10, john 13 and so on.I want to sort the second list from large to small, but have the index for the first list still linked to the correct amount of calls.i do it this way so I can
for x = 0 to num_of_names
string = lst_name(x) & "-" & lst_count(x)
next x
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Dec 16, 2009
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.
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Jan 6, 2012
I want to do translation recursively on all components in my form. So my function will start on the form. Before the recursion, it's obvious that I have to know what property containing the children that the current Object has.[code]...
The method I want to use it, I will check if the current object has property Items if not, check if it has property Tabs, and so on... Then the last fallback, check if it has property Controls.
Now the very question how could I check if the current object has specific Property?
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Apr 24, 2012
Let's say I've got a TableLayoutPanel with 50 cells in it. Inside each cell is a separate text label. If I want to change the color of each of those 50 labels at run-time to the same color, is there an efficient way to do it? (so that I don't have to write 50 lines of LabelX.ForeColor = X, etc).
Not that I would mind writing 50 lines of code for this, but I would like to figure out the most efficient way to do this sort of thing, for future reference.
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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
Next
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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Apr 20, 2009
I got some set of base classes within one namespace and few sets of derived classes in other namespaces. Everything in one project.[code]...
OK, it can be done declaring .SubElements as Protected in BaseElement class. But in this case I cannot access this property from other classes in Base namespace that are not derived from it.
I tried adding Friend keyword, but it made this property visible when I'm instantiating derived classes too.
So... any way to hide some properties when using derived classes while being able to use them using base class?
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Feb 17, 2012
I need to determine the ranking of the List items specified by one specific property of the items.
I have the following Class:
Public Class LevelA
Property items as New List(Of LevelB)
Public Class LevelB
Property factor as Double
ReadOnly Property rank as Integer
End Class
End Class
For example, let's say I have three items in the List. I have set the factor property for the first item as 5.50, the second item as 6.60 and the third item as 3.30.Now I should be able to get the rank property of each item (the highest value should be ranked as 1). Here the first item in the list should have the rank as 2, the second item as 1 and the third item as 3.
What kind of procedure is needed for the "ReadOnly Property rank as Integer" for returning such values? It should somehow be able to access the list in the parent class probably?
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Aug 11, 2010
I currently have a XML file for an application I am developing. I have built a a XMLFile.GetContent function to read my XML File and load the content into a set of specific objects. These objects are then added to a collection and passed back to the main code to be loaded into the memory of the application.I am looking for a dynamic way of loading the information from the XML file into a specific Object Property. I have added comments to the function to show what I want to make dynamic.Content of XML File
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Config>
<IQSDataSources>[code].....
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Apr 13, 2012
Consider:
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.
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Aug 14, 2010
I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
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Nov 25, 2011
I am trying to construct a generic interface class with generic functions. My goal was to use this to implement multiple worker classes for database interaction that have the same basic functionality. Each class will deal with different object for example, category, product or supplier but unless the the functions in the interface are generic that this won't work.This is the interface code that I have but I don't know if I have done it correctly. [code]
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May 20, 2010
I know how to check whether an item exists in a list using (MyList.Contains), But I do not know how to check the whole list. For example (use one button and one richtextbox):
[Code]...
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Jun 30, 2011
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.
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Feb 8, 2012
I am trying to write a generic method, to avoid code duplication, which will create or activate a Form as an MDI children, based on its type. But I have to lines in error (see comments).
[Code]...
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