Making Variable Class With Event?
Jun 22, 2010
I haven't quote grasped this whole "class" concept yet, but I'm working on it. When following the instructions below, the "test" portion of this code: "test.variable". It has an underlined error that says that "test" is not declared. If I remove the "test" word then the ".variable" shows not declared. I'm using Visual Studios 8 if that makes any difference. I have a pre-existing variable in a project that I would like to monitor for changes.
Re: Detect variable change.
Make your variable a class with an event.
Make your class:
VB.NET Syntax (Toggle Plain Text)
Public Class myVar
Private mValue As Integer
Public Event VariableChanged(ByVal mvalue As Integer)
[Code] .....
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Jul 6, 2010
I'm making a custom class that mocks the System.Drawing.Rectangle class because the Rectangle class doesn't have a name property. I need a name property because I am adding all of my rectangles to a collection and I need a little more info stored than just their locale and size. So I changed the _onPaint event but nothing is working out when I run the program?
Public Class Rectanglar : Inherits UserControl
Public BackgroundColor As Color = Color.Blue
Public Sub New(ByVal name As String, ByVal XY As Point, ByVal Widthy As Integer, ByVal Heighty As Integer)
[code].....
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Sep 3, 2010
What does this error mean? I havent modified anything in the designer code, but its giving me an error? WithEvents variable 'Move' conflicts with event 'Move' in the base class 'Control' and should be declared 'Shadows'. The error relates to Friend WithEvents Move As System.Windows.Forms.DataGridViewCheckBoxColumn
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Dec 27, 2010
Is it possible to raise event in one class and handle the event in another class? If so, how?
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Sep 26, 2011
i had a class called Tag with a structure like:
public class Tag
private _members
public properties
public shared database_methods
end class
this class was tailored for mysql database. i'm currently adding access 2007 support so i split tag into tag and tagdata with structures like:
[Code]...
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May 8, 2012
Create a class named Service. Inside the Service class, declare a class variable named Started. The datatype of this variable is Boolean.Public Class Service Dim started as Boolean End Class Create a class named Server. Inside the Server class, declare a dynamic array that can contain elements of the type Service.(Note: For convenience, both the array and the variable Started can be accessible from a client program that creates an instance of Server and Service respectively)
Create a constructor for the Service class. When the constructor is executed, it will set the value of the class variable Started to True. Create two new classes: WebServer and DatabaseEngine. Both of these classes inherit from the class Service. Inside the Service class, declare a Sub procedure (method) named Terminate. This method should display the following text Service stopping in a message box when executed.This method can be overridden in classes that inherit from Service class.
Inside both the WebServer and DatabaseEngine class, override the method Terminate inherited from their base class Service. Both methods should first call the base class Terminate method. The messages Web server stopping and Database engine stopping should also be displayed in a message box when the Terminate method for the WebServer and DatabaseEngine are called respectively. These messages should only be displayed if the Started variable inherited from their base class is not equal to False.
Inside the Server class, declare a method named Shutdown. This method does not return any value. When executed, it will call the Terminate method for each of the Service instances (if any) in the arrServices
array. You should call the Terminate method within a For Each loop that loops through the elements of the arrServices array.
In the Sub Main method, create an instance of the class Server. Set the size of the arrServices array in
your Server instance to contain 2 elements. Create first a WebServer instance and then a DatabaseEngine
instance into this array. Call the Shutdown method from your Server instance.
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Jun 7, 2012
I want to created a nested class that can only be visible to and instantiated from the parent class.But I also want to be able to use an instance of the nested class through a public variable of the parent class.I tried making the nested class private, or making the nested class' constructor private, but it won't compile.Is it possible to do this in .NET?
[Code]...
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Jan 16, 2009
i declared a global variable button:
Dim button1 As New Button()
Now, i dont know how to add a click event in this button since it is a variable.
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Sep 29, 2011
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]....
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Nov 14, 2009
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]
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Dec 18, 2009
What i'm trying to do:
I've got a library which includes a class:
Class Human
End Class
and another class which refers to the human class
Class ASD
Private somevar as new Human
End Class
Ok now i've got a problem, i wish to rename my class Human, to Man. i've got to change Human to Man 2 times, which is OK but the problem is that in the real case, its not just 2 times, its like 500 times or more.
Well its something like a PHP on Javascript.
the following shows the solution of what i'm trying to do, but its in another language PHP/Javascript:
note: in php $ sign declares a variable, echo writes the variable out
CODE:
Is there anyway to do that with VB?
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Jun 7, 2009
Okay this one might be a little tougher. I'm using VB that looks like this:
string = Replace(string.ToLower, chr(63), "A")
But I also want chr(63) = "B" as well, like this:
string = Replace(string.ToLower, chr(63), "B")
My problem is that when chr(63) is at the end of a string I need it to be B, and when it's not the end I need it to be A. I suppose that I can use an if/then/else statement. Is there a way to do this?
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Dec 10, 2009
I was wondering if there's a way I can make my objects return their own variable name as a string, something like this:
Public Class MyClass
Public ReadOnly Property VariableName() As String
Get
[Code]....
Is this possible? I'm fairly sure it should be possible through the System.Reflection namespace, but I can't figure it out.
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Aug 3, 2010
How do I optimize my code making it DRY approach. I want to make my variable to be on public/general so i can re-use it
Public Class BasicForm
Dim Product1, Product2, Product3, As Integer
Dim firstName, lastName As String
[code]....
I want to move the variables (product1,product2) to somewhere else that I can set it one time and easily access it with other control. What I did before is I alway set the variables to every control.
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May 5, 2011
excuse my coding and term limitations. I'm still learning and have only done what I'd consider basic things. I tried to search this solution for hours and but I'm coming up with nothing.
What I want to do is to reference different check boxes using one loop.
Like this..For xItemNo = 0 To 3
[Code]...
I get the error "Public member 'Checked' on type 'Boolean' not found." I get the fact I'm not able to simply make the text of the code into a variable I can easily insert into the code at will. At least not how I'm trying to do it.How can I dynamically change the check box name I'm referencing in the loop so I don't have to duplicate the code over and over for every check box name?
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Nov 18, 2010
I have a class that is stored after serialization and compression.Is there any event built in the class that is fired automatically when a class is deserialized and ready to be used??
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Jan 31, 2011
I have the following code:
Option Explicit On
Imports System.DirectoryServices
Imports System.IO
[code].....
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Jun 9, 2009
If I For Example Made a New Control Like :
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Nov 3, 2009
I'm trying to make a calculator application. Just as practice, as I'm new to visual basic (.NET 4.0) coding. I've got this so far.
[code]...
Note, I've not programmed it to do operations yet, I'm trying to get this sorted out first. My issue is, when I enter my numbers, they do not store as a variable, they both store as zero.
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Apr 14, 2009
I have a "partial" class in VB.NET. Half of it is auto generated by a code generation tool. That half implements INotifyPropertyChanged, so any properties in that part of the partial class raise the PropertyChanged event.In my "custom" part of the class, I declare another property that depends on one of the properties in the auto-generated side. Therefore, when that auto-generated property changes, I also want to raise a PropertyChanged event on my custom property that depends on it.
If I go into the generated part of the class and raise the event there, that will get overwritten if I ever re-generate that part, so I don't want to do that. I would rather add an event handler in my side of the partial class that checks if the generated property changed, and if so, raise another event for my custom property.
[Code]...
I'm assuming it's because normally you'd use the WithEvents keyword to tell the compiler that you're subscribing to events from that object. I don't have a clue how to do this inside of the class that's actually raising the event, or if that's even possible.
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Feb 9, 2011
The code below works for the class that I hard coded "XCCustomers" in my RetrieveIDandName method where I use CType. However, I would like to be able to pass in various classes and property names to get the integer and string LIST returned. For example, in my code below, I would like to also pass in "XCEmployees" to my RetrieveIDandName method. I feel so close... I was hoping someone knew how to use CType where I can pass in the class name as a string variable.
Note, all the other examples I have seen and tried fail because we are using Option Strict On which disallows late binding. That is why I need to use CType.I also studied the "Activator.CreateInstance" code examples to try to get the class reference instance by string name but I was unable to get CType to work with that.When I use obj.GetType.Name or obj.GetType.FullName in place of the "XCCustomers" in CType(obj, XCCustomers)(i)I get the error "Type 'obj.GetType.Name' is not defined" or "Type 'obj.GetType.FullName' is not defined"
'+++++++++++++++++++++++++++++++
Imports DataLaasXC.Business
Imports DataLaasXC.Utilities
[code]....
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Mar 10, 2009
I am using visual studio express edition 2008. I am trying to move my class.vb files in my web application to one .dll. I used visual express edition 2005 earlier and I had to add to import the below code to get it to work. Now in 2008 edition I get a whole new error and I need to know what I need to Import. Code is below
2005:
Imports Microsoft.VisualBasic
Imports System.Configuration
Imports System.Web
When I do the above in 2008 I get the following errors:
Shared mainconnection As
New Data.OleDb.OleDbConnection(ConfigurationManager.ConnectionStrings("connectionstring").ConnectionString)
Error: Error 1 Name 'ConfigurationManager' is not declared.
[code]....
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Oct 29, 2007
I was wondering if it was possible to make an array of a class. I made a class called creatures (for a game of course) and wanted to make an array of that class. So I tried "public creature() as new creatures", and it had a problem with using an array with new. Is there a way around this. All I am using the class for is variables. i.e.: in my class all i have is dim health, defense
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Jan 23, 2011
I am currently developing an application in which I would make a form full size automaticly.On the location where I set the time parameters, lets say, I want an event to occur every 2 hours, in which the event would be a form becoming full-sized and, on that form a clock which would show that the form will resize on its original state after lets say, 15 minutes.And also I would like to disable the Windows Start keys.I tried some codes but they were for an event if the key is pressed.For this I need the keys to be disabled as soon as I start my application.For the full size form I have used this code:
Me.Height = My.Computer.Screen.WorkingArea.Height
Me.Width = My.Computer.Screen.WorkingArea.Width
Me.WindowState = FormWindowState.Maximized
Me.FormBorderStyle = Windows.Forms.FormBorderStyle.None
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Nov 15, 2010
I am thinking is to have a question, then between 2-4 answers, and depending on the answer a point value gets assigned to a variable, but then when that one question is answered you can click a button that moves to a next page type of thing with a new question on it. I think I could probably figure most of this out but when it comes to switching to a different question I am not sure how I would do that.
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May 2, 2011
I'm making a blackjack game for class. It's been better programming in VB than it has in C#, but I don't know how to link button subs (BTN_Deal_Click or BTN_Deal; I can't decide which one will work) to one another. For example, after the code in BTN_Deal has been run, the program is supposed to wait for the user to click either the Hit or the Stand button.
[Code]...
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Feb 26, 2012
Am making a mario type game for a college project and really want to get close to mario, apart from the physics which seem to be harder then I thought.Here is my current code for making my RectangleShape (named 'player') bounce once:[code]This should work, however i can still bounce more than once while remaining in mid air.
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Dec 21, 2011
I am trying to make a customer class that will simply make a bunch of controls (hotspots) Visible value = False.
For instance: WinStartSpot.visible = False
Thing is I have roughly 60 "spots" that need to be turned on and off as the user clicks through the program (its a very simple OS simulator) I tried to make a class using boolean return but that failed miserably. how to code a class like that?
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Jun 15, 2012
I have a ComboBox that is databound to an ObservableCollection of strings. The ComboBox is also editable, so you can either enter in your own value or select one from the list. The issue I'm running into is the index of SelectedItem seems to be the index of the last item you selected when you've entered in your own value in the ComboBox, though it's -1 when you have IsTextSearchEnabled set to true. The problem is, if someone entered their own value and then decide to instead select the item on the ComboBox that had been selected before, the index doesn't change so the SelectionChange event doesn't fire. How could I get an event to fire in this situation?
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Aug 17, 2010
make a click event for a non existing control but for example: when the end user clicks the new button(or something else) a new text box pops up with a button on the same form and when the button is clicked I want the form to open another window(or something else). Here is the the code for doing that(only the part needed):
Private Sub MenuBtnNew_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuBtnNew.Click
Dim Tab As TabItem = TabControl1.CreateTab(NewDialogBox.NameBox.Text + NameDesign)
Dim Panel As TabControlPanel = DirectCast(Tab.AttachedControl, TabControlPanel)
[code]....
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