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.
View 2 RepliesI'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.
View 4 RepliesI 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]...
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]....
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]
View 2 RepliesI 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?
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]...
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'.
View 1 RepliesI have a MyObject; myObjects as List(Of MyObject) and a delegate Comparison(Of MyObject) that uses a lot of comparison functions (ByA, ByB, ByC etc) Ã la:
Shared Function CompareMyObjectsByName(x As MyObject, y As MyObject) As Integer
Return x.Name.CompareTo(y.Name)
End Function
[Code].....
I have a List(Of T) storing a list of Custom classes called Advertisement. Each advertisement contains 3 properties, Year, Make and Model. I need to sort the list By Year, then by Make and then by Model. I have a property in the Advertisement class called Vehicle which returns a formatted string with the Year Make Model like 2007 Toyota Tacoma and ive been sorting on that but its not working how I thought it would. Basically I want to sort the list by Year (decending; lowest year first) then sort by the Make and Model (in alphabetical order) Is that even possible? Here is the code ive been using.
[Code]...
I'm having a bit of a 'brain doner' moment here
I have a list of Objects. Each of these Objects contains a list of other Objects (pseudo code) :-
Private Structure Object1
dim Name as string
dim ListOfObject2 as List(Of Object2)
[Code]....
I need to sort the list of Object1 by the Value in Object2. I have a comparison class which sorts Object2 by its Value nicely.
In my application I have a class called "RCategory" as illustrated here:
Public Class RCategory
Public Property RCatNum As Integer
Public Property RAct As Char
[code]....
I'm trying to add to my list using the following code:
For ct As Integer = 1 To 8
Dim c As New RCategory With {.RCatNum = ct,
.RAct = dr("RACT" & ct.ToString).ToString,
[code]....
I'm getting an error when I get to the bottom line, though...when I actually execute the RCat.Add(c),I get a System.NullReferenceException was unhandled by user code Message=Object reference not set to an instance of an object. What must I do to be able to use a List (of T) in my class?
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
I have a very simple class that holds a few public properties - ID, Text, Colour, etc. and a Boolean called 'SelectedItem'. Just like the Checked property on RadioButtons, only one item can have its SelectedItem property set to True within a particular group. Note: there will be several separate groups (lists), each allowed to have only one item with SelectedItem = True.
My first thought was that I would probably just have to handle everything outside of the class, setting SelectedItem to False for every other item in a particular list when another item was selected. But that seems rather inelegant to me. So I've been trying to think of how this might be done within the class. For example: could I perhaps have a private string property called say "GroupName" - set in the New sub when adding a new instance of the class - and then use a private shared method to set every item's SelectedItem property to False, provided the item has the same GroupName as the newly selected item? I would have a go at doing this but I have no idea how to enumerate every instance of a class from within that class, or whether that's even possible. Is it? Or is there another (better) way to achieve my goal? Here is a cut-down version of what I've got so far:
Public Class ResourceItem
Public ID As Integer
Public Text As String[code]....
As can be seen: instead of instantiating a new ResourceItem and passing that as an argument to the manager's Add procedure, I'm simply passing the details of the new item and the procedure is creating the item from those. I don't know whether this is a good or bad idea - please advise - but I've done it because I couldn't figure out how to make the SelectedItem property only writeable by the manager, so I wanted to avoid having directly accessible objects that could have their SelectedItem property set to True without it deselecting all the other items in the same group. Of course that still leaves the possibility of setting a variable to one of the manager's list items and setting it from there, so I would still like to know how I could prevent that, if possible.
UPDATE: I didn't use the code above in the end, deciding instead to go with Cyborgx37's solution - which seems to work perfectly well for me despite the warnings about best practice. I also realised I would need to use the same class in another scenario where multiple items could be selected, so it was easy to add a Boolean property to the manager to enable that.
I am using the following code to load a file into my program, everything works fine. When I open a new file everything works fine unless I have this line inserted:
Me.BindingSource4.Sort= "NewDateSold Desc"
That line works unless I open a new file while in the same instance of the program running. The I receive the following error:
Sort string contains a property that is not in the IBindingList.
File Open Code
Private Sub OpenToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OpenToolStripMenuItem.Click
OpenFileDialog1.InitialDirectory = "c:"
OpenFileDialog1.Filter = "Text Files (*.txt)|*.txt|CSV Files (*.csv)|*.csv"
[Code] .....
I am really confused since everything works properly if I comment out the
Me.BindingSource4.Sort = "NewDateSold Desc"
I have the following property in a property grid in VB.Net 2010.
<Description("Rapid Entry Post Car Wash Settings CarWashOptionPushButtons"), _
Category("Post Car Wash")> _
Public Property CarWashOptionPushButtons() As String
[code]....
I need to make this property a list box that gets the values from a database table and populates the list box with the values from the table. I have tried numerous things to no avail.
to be able to print a list of objects in a user-defined way, i've implemented an IComparer (sortclass), which is able to sort any object by its property. I have a list that can be printed (first a pdf is generated trough the object, then passed to the printer), all done by clicking 1 button (print button).
The internal ICollection (list of) is perfectly sorted, however, the routine to create and print the objects is apparently called to soon... since not all objects are completely sorted when send to the printqueueu. A check of the list after all objects has been send to the printer proves however that the list is printed.
[Code]...
I have the following code:
Public Class MyColorsClass
'Constructors
Public Sub New()
'Empty Constructor
[code]....
However, if the empty constructor was called to instatiate this class then the colortype is not yet set. Therefore, if one accesses the 'IsColorCool' property it will always return 'False'. Now for the sake of this example, I must keep the empty constructor as part of the class.Now I could add some code in the 'IsPropertyCool' to check and see if a ColorType has been defined, and throw an exception if it has not been set, but I don't really want to do that.I also could always move the logic OUT of the property and into a method on the class called 'DefineIfColorIsCool' or something, and make the owness on the caller to make sure the method was called if they want to use the property 'IsColorCool'?
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)?
I have procedure (Import) that calls a for a new instance of frmImportData. I also have a class name clsBatch that has a data table property called prpParametersTable.For some reason, I get an error (indicated below with ERROR>>>) when trying to assign prpParameterTable to cv_dtImport2. The error states "Object reference not set to an instance of an object.". Why does this error not happen when I assign dtBP to cv_dtImport1? Both cv_dtImport1 and cv_dtImport2 are equal to Nothing and in my Import procedure dtBP = prpParametersTable.
Public Sub Import(ByVal clsB As clsBatch)
Try
Me.cv_clsB = clsB
[code]....
I have three class files, accounts.vb and transactions.vb in addition to my form.vb. I am unable to retrieve a member variable from on class from inside the other. When the combobox index changes, the program loads the correct account (checking or saving) from two different sequential files. I don't think I have the calcBalance procedure in the correct class file. And that is what I am having trouble with. Accessing it to display it. [Code]
View 1 RepliesThis is a bit of a continuation from a previous post for which AtmaWeapon was very informative.
Problem:
A parent class has a sub class with various properties. A property of the parent class is a List(of T) with T = the sub class The issue is how to store data in the sub class of the instantiated parent
Some example code (hopefully formatted correctly):
Code:
'=========== Class Definitions =============
Public Class courseClass
Public Class timeTableClass
[Code].....
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)
I have a class that has the following property that is generated by the methods in the constructor.
Public Class clsLoadTables
Private _ds As New DataSet
Public Property ds() As DataSet
Get
[CODE]........................
My problem is that I do not want to inherit this class, but I have other classes that need to access the ds DataSet property. If at all possible I would like to not use inheritance and not load my datatable more than once in the program.
Here is my failed attempt to access the property inside another class that is not inheriting clsLoadTables:
[CODE].........................
How I can access this dataset that I want to load only once in the program from many classes without using class inheritance or a global module?
I know that an interface can contain another interface within it.But;can a class contain another class within it?Can an interface contain another interface within it?
View 9 RepliesSorting an array of my own class error
View 8 RepliesI'm having problems doing a sort of a custom collection. The collection is Device Classes which is a collection of Device Class. My sort does not produce an error but the treeview control shows nothing. I am not sure what I am missing. I'm guessing just a simple sort won't work here but I don't know what I'm missing in my code. Here's the code that creates the collection
[Code]...
Simply sorting the treeview will not work because it throws off the display of related info for a given device in listview controls. The collection itself needs to be sorted before the data is added to the treeview.
i have a list of datarows. each row is having mutiple columns like userid,date,flag,etc.i want to sort the based on date. how can i do that ?
my code is:
Dim
listOfRows As
New List(Of
DataRow)()
[code]....
i want to sort the listOfRows in ascending order of date which is a column in a row?
i wrote the following code to sort a list of word:
Public Class Sort_DT
Public Sub Words(ByVal index As Short, ByVal Incoming(,,) As String, ByVal Level As Integer)
[code]....
when words sorted, application used over 300 MB of memory;
I'm trying to sort an arraylist the code is below.
the value.sort() is returning the following error - Failed to compare two elements in the array. At least one object must implement IComparable."[code]...