.net - Overrides A "list Of Base Class" Property And Returning A "list Of Child Class"
Oct 19, 2010
I have a base class (ex: Class1) containing a list of another base class (ex: ClassA). Each child class of first base class (ex: Class1AA, Class1AB,..) containing a list of child class of second base class (ex: ClassAA, ClassAB,...)The client must never know which child class is using, then i don't think i can use generic for my bases classes.I try something like this and many more, but i always received errors..Imports System.Collections.Generic
[code]...
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Sep 25, 2009
I suspect I am being very silly here but I have the following setup
Class MustInherit myBaseClass
'some stuff
End Class
Class myInheritedClassA
[code]....
Running this results in the following error
Unhandled Exception: System.InvalidOperationException:
There was an error generating the XML document. --->
System.InvalidOperationException:
[code]....
is there any way of 'Widening' the inherited class to the base class so this would work?
EDIT:regarding XmlInclude(typeof inheritedClass), currently this method could potentially return a number of types of inherited class (i.e myInheritedClassA and myInheritedClassB) is it case of simply having to add each of the inheritedTypes in this tag?
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Apr 2, 2010
I'm looking for a tutorial on how to Adding a list(of Class) or Collection as another Class's Property.What I am after is something like the Columns Collection for the DatagridView control.I would like to add Items in the graphics screen. Where the item list is displayed in the left panel and the selected Item properties are displayed in the right panel.
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Dec 29, 2010
This is another one of my "I think it's not possible but I need confirmation" questions.I have a base class for a bunch of child classes. Right now, this base class has a few common properties the children use, like Name. The base is an abstract class (MustInherit)Technically, this means that everytime a child class is instantiated, it lugs around, in memory, its own copy of Name. The thing is, Name is going to be a fixed value for all instances of a given child. I.e., Child1.Name will return "child_object1", and Child2.Name will return "child_object2".
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Apr 7, 2011
Supose a base class
Public Class airplane
Private var_num_seats As Integer
Private var_num_engines As Integer
[code]....
Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?
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Feb 27, 2012
VB Reference parent member of a class through a child when using List Of(T)?
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Oct 14, 2009
Stack Overflowers:I have been racking my brain trying to get an List(of T) type array to be the property of a class. I know there has to be a simple way of doing it and I can't find a good example on google. Everytime I create a class that I think will work I get the "Object reference not set to an instance of an object" error when I try to use it. My thinking now is that I cannot use it in the way I was hoping to. Here is my latest attempt:
Public Class Item
Private _itemno As String
Public Property ItemNo() As String
Get
[code]....
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Apr 2, 2010
This is another continuation of an issue with a List(of T) as a property of a class.Following the excellent advice of AtmaWeapon and others on this forum, I have my classes working fine except for something that is inexplicable to me.I initialize my "course" class at a public level in a module. This is so the data in the class will be available program wide and for the application's lifetime. "Public newCourse As New Course".I initialize a local instantiation of the class TimeTable as newTimeTable [code] This issue is: The List(of T) is populated with data, however, when the loop finishes, what I have is the last set of values repeated "X" number of times in the List instead of the data being different in each element of List( Of T). [code]
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Oct 8, 2010
I have a class called Questions. This Questions has properties QuestionID and QuestionAnswer. My list of Questions has QuestionID like 2, 3,4, 15, 12, 24,22,,,, etc.I need to sort this List of Questions Object based on QuestionID and store in another Questions object.
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Oct 4, 2011
I have the following class:
[Code]...
I could be way off here, but it almost seems like ID.IDlist points to the address of mylist and so when mylist is cleared so is ID.Idlist. It seems as though the reason the second block of code works is because I am creating a new list in memory for each ID object and ID.IDlist just points to it... is that right?
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Jul 5, 2010
bare with me during this silly example. :-) Let's say I have a class like this:
Public Class Animal
Public iLegs as int32 ' Number of legs
Public bWings as Boolean ' Wings? Yes/No
End Class
And another class that inherits the "Animal" class and adds one more property:
Public Class ScaryAnimal
Inherits Animal
Public iScariness as int32 ' 0-100, how scary is it?
End Class
Now, if I have an instance of "Animal" with some values in it, and I decide I want to cast it to a ScaryAnimal for some reason, how do I do that without having to create a new instance of "ScaryAnimal" and copy each property value?Basically I'm looking for a way to do this, without having to write the lines marked with '*** below:
[Code]...
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Mar 12, 2011
I have a file name that is found at multiple paths. I want to present this data to the user in the format of a DGV. I have a DGV with one text box column for the name, and another combobox column for the paths. I am having trouble getting the combobox column to bind to the property of the class that returns the paths.
[Code]...
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Nov 29, 2011
Is it possible to create a user control with a list of custom class type property? If it is, how can I? The issue is that, in designer mode the property is not displayed in property window. I can add the list on markup but when i switch to the designer mode it gives an error which is 'The user control does not have a public property named BookList'.
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Apr 15, 2010
I have put this code in the global form Inherits System.Windows.Forms.Form. And then in the form that will inherit this from the global Inherits MenuStrip. "MenuStrip" is what the global form is called. But keep getting this error: Error1Base class 'MenuStrip' specified for class 'Lesson2' cannot be different from the base class 'System.Windows.Forms.Form' of one of its other partial types.
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Apr 27, 2011
I want to read a number of items from a file and then associate each of those items with a new button at run-time, so that when the user clicks one of the buttons I can display some information about that item.Can I use a LIST to manage these buttons and items? Can I create a new class and have each list item of that class, such as 'btnID', 'btnText', etc... ?
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Mar 8, 2010
I have got an xml document which looks something like this.
<Root>
<Info>
</Info>
<Info>
[Code]...
How can i write a linqToXML query so that it returns me an IEnumerable containing each child element, in this case all five child elements of , so that i could iterate over them. The order of child elements is not definite, neither is number of times the may appear.
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Jun 21, 2010
I am trying to create an list or an array of a class.Here is my "Ingredient" class that I am trying to create a list of:[code]In my "recipe" class, I am want to create a list (or array) and I am drawing a big blank on how to do it. Can anyone point me in the right direction?
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Aug 22, 2011
I inherit from ListView. I want my control to have an AllowCheckBoxes property rather than a CheckBoxes property.
Listview.Checkboxes is not overridable.
Can I add attributes to Listview.Checkboxes? Maybe the following?
<Browsable(False), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)>
If not, does the following make sense?
<Browsable(False), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)>
Public Property Shadows CheckBoxes() As Boolean
Get
[Code] .....
What about using
EditorBrowsableState.Never)
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Mar 23, 2011
Public Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()
[code]....
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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Nov 5, 2011
I wish to make a project where a teacher views a list box with a list of students of a class. When he selects a name from the first list box the second listbox would change its data to show the grades for that one student.
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Jan 27, 2011
I'm getting System.NullReferenceException error when I try to add the employee info to the Employees list.
[Code]...
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May 26, 2012
y have this class
Private Class MyClass
Public Property propertyOne() as String
Public Property propertyTwo() as String
[code].....
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Mar 6, 2012
I am trying to understand classes in VB 2010. I am a bit confused with displaying information from a list into a listbox.When I run the following code, the word collection appears in my list box. How do I drill down into 'hostnames' to display the info I want.
Public Class computer
Private _HostName As String
Public Property HostName As String
[CODE]...
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Jun 3, 2011
I'm designing a small GUI Windows program that allow staff at a cinema to reserve seats for customers. There will be a total of 60 seats in the cinema. I have two classes in my program:-
1.) MainForm.vb - used for I/O actions and user interaction
2.) SeatManager.vb - used to hold and handle the background methods and functions that make the program work Here is the code for my MainForm.vb class thusfar:-
[Code]...
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Apr 28, 2009
I seem to have problem with passing a collection/sorted list/ list of strings from one class to another.I am using property procedure to pass it, however nothing is sent to another class. There isn't any error messages either.[code]
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Mar 12, 2010
When I do this
Public Class cInherits : Inherits Panel
I get this: Base class 'System.Windows.Forms.Panel' specified for class 'MenuButton' cannot be different from the base class 'System.Windows.Forms.UserControl' of one of its other partial types.
How do I inherit?
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May 14, 2009
I would like to have a form class that is called from a button on a parent form and would like a button on the child form to set a property on the parent form. Can anyone explain the best way to go about this or direct me to a good article?
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Oct 1, 2008
I've been creating short test apps repeatedly to try to understand some of the concepts in VB.NET.For the most part it has been illuminating.I read Bucky's .NET knowlegebase tutorial on passing objects as parameters to newly created forms. He shows how to create a new class that inherits from the base form class and define a New() method with parameters Extending the concept I thought about doing the same thing with a form that was created at design-time (In this case Form2).
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Apr 22, 2012
Base class has one field to hold numeric balance value. With 2 methods that accept arguments for adding and subtracting the new input calculating new balance. Sub class has four fields dates, transaction, memo and amount.I have a deposit form, and withdraw form. Each time one transaction is entered it creates an object with sub class fields, then adds to the account collection. My problem is not understanding how to call the deposit/withdraw method and pass the current transaction amount back to the base class to alculate the new balance. Does anyone have any links to information/tutorials on how to perform something like this? As you can see with my code I have tried various different approaches without any success.
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Apr 9, 2010
I am trying to create a class in VB.NET which inherits a base abstract class and also implements an interface. The interface declares a string property called Description. The base class contains a string property called Description. The main class inherits the base class and implements the interface. The existence of the Description property in the base class fulfills the interface requirements. This works fine in C# but causes issues in VB.NET.
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