How To Access Variables In Another Class Without Deleting Any
Oct 31, 2011
I have been charged with porting a VB6 project into VB.NET. In vb6, if you were in a class separate to a particular variable, you could access that variable easily:
Public Class Foo
Public k As Integer
End Class
Public Class Bar
k = 12
End Class
In VB.NET, my understanding is that before you can use a variable in another class, you must declare a new instance of it:
Dim foobar As New Foo
This would be fine, but I have to access these variables from different classes and every time I declare a new instance, it wipes all old values from the variables, which I need. I tried using Inherits statements but they presented many problems.
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Jul 23, 2009
I am making a small application in which i have added a class module and a window forms in vb.net. i want to acess the shared variables and mathods of class without making any object.
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Jul 29, 2010
how variables declared with protected access in a base class are used to implement inheritance.
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Mar 23, 2012
I define some global variables of a class as follows:
Private Class MyClass
Private var1 as Decimal
Private list1 as List(Of string)[code].....
But I found that after this form is closed, all above variables, var1, list1, list2 still exist in memory. I thought they should be collected by gc since the form is already disposed as I confirmed.
Add: I have monitored half an hour after the form is closed. But these variables are not collected by gc. I have an automatic update procedure on the form which uses above variables.Since the above variables still hold values, the automatic update procedure is always called which causes exception. (One quick fix is to check if form.isDisposed in update procedure. But I do not think this is elegeant. Besides, these variables occupy memory.)
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Jun 9, 2012
I'm new in .NET programming.I have a class Form1 that includes Button1_Click event.Button1_Click creates a multiple Text Boxies at run time)Here is the class:
Public Class Form1
Dim shiftDown As Integer
Dim counter As Integer
[code].....
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Sep 6, 2009
I have a form called 'Form1' in my .NET Project.
When I double clicked the form it went into the code editor.
However, I accidently deleted the statement
Public Class Form1
End Class
how can i get this code back?
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Mar 17, 2010
[code]Index was out of range. Must be non-negative and less than the size of the collection.Parameter name: index
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Jul 16, 2009
when i had 3 text box then i did the following code and it worked for me also:
Imports System.Data
Imports System.Data.OleDb
Public Class Form1
Dim con As OleDbConnection
[code]....
in the above code ,depending on the textbox3.text,i performed all the deletion,so it was easy now i have got a three of combo box and three text box....... i filled the combo box with the database entries.....now i want to perform deletion depending upon the selected items of any one of the three combo box........i cant get the logic of the where portion in the delete syntax.....
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Mar 4, 2010
I'm trying to delete a record from my access db using code and am getting an error message.My code is as follows:
Dim mDataPath As String = Application.StartupPath
Dim strSelectedItem As String = DataGridView1.Rows(DataGridView1.CurrentRow.Index).Cells(0).Value
[code].....
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Sep 18, 2009
I need a good book for beginning to use VB 2008. I have some (limited) experience in using VBA. I want to access a database (SQL) and have access to the data set as variables?
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Jul 25, 2009
Im having some trouble figuring out how I should delete these items. I want it to delete the one I have selected in the listview and delete the corresponding item in the DB. Ive tried various combination's and this is the latest one I have:
[Code]...
So where am I messing up? I keep getting errors no work done but when I close the form2 and open it back up no DB items show up in the Listview. But I close my project, and open it back up and they're back. All while never changing in the DB.
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Mar 15, 2012
I have this problem : Dynamic SQL generation for the DeleteCommand is not supported against a SelectCommand that does not return any key column information.... the button used to delete record in my project is button6 at the end of the code
My code :
Public Class Form1
Dim con As New OleDb.OleDbConnection
[CODE]....................
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Jul 16, 2009
when i had 3 text box then i did the following code and it worked for me also:[code]in the above code ,depending on the textbox3.text,i performed all the deletion,so it was easy now i have got a three of combo box and three text box.i filled the combo box with the database entries.now i want to perform deletion depending upon the selected items of any one of the three combo box.i cant get the logic of the where portion in the delete syntax.
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Feb 28, 2012
I am making a program that takes Access records and moves them into MySQL then checks to be sure everything is right and deletes the moved records. But, for some reason my delete command isnt working....
Here is the
Dim deleteCommandF As New OleDbCommand
Dim deleteCommandE As New OleDbCommand
Dim deleteCommandO As New OleDbCommand
[code]....
Running the program now to get the exact error message, shouldnt be more than 5 minutes and I'll post it.It says my paremeters are wrong? deleteCommandE.ExecuteNonQuery()
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Jun 4, 2010
I am trying to add shared members in derived classes and use that values in base classes...
I have base
class DBLayer
public shared function GetDetail(byval UIN as integer)
dim StrSql = string.format("select * from {0} where uin = {1}", tablename, uin)
end function
end class
[Code]..
currently there is error using the tablename variable of derived class in base class but i want to use it i dun know other techniques if other solutions are better then u can post it or u can say how can i make it work? confused...
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Aug 12, 2009
I have an MS Access database that has a field called DeletedDate. I want to use a Delete statement that will delete the record(s) when DeleteDate is 30 days old or older. I have tried several different Delete statements but none seem to work properly. They will always delete some of the records, but will leave some records where either DeleteDate is older than 30 days or will delete recored where DeleteDate is not yet 30 days old. I have tried these using DeleteDate as a Text field and as a Date/Time field. Which should I use? These are the Delete Statements that I have used:
'sComm = "DELETE from Agents WHERE Deleted = 'Y' AND DeletedDate < " & System.DateTime.Now.Date.AddDays(-30) & "
sComm =
[Code]....
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Apr 3, 2012
I am trying to delete a record from a table by using dao recordset. Currently I am working with the code listed below. Unfortunately i've realised that this code only deletes the first record in my table, whereas I am looking to delete a record form the table with an ID that I would have put in textbox1
Private Sub btnDelete_Click(sender As System.Object, e As System.EventArgs) Handles btnDelete.Click
Dim AccessEngine As New DBEngine
Dim db As Database = AccessEngine.OpenDatabase(DatabasePath)
Dim dbs As Microsoft.Office.Interop.Access.Dao.Recordset = db.OpenRecordset("myTable", RecordsetTypeEnum.dbOpenDynaset)
dbs.Delete()
End Sub
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Nov 1, 2010
in pervious version of VB (DAO 3.6) I used to be able to delete a query object and then creating it again (not the records) using the code below. but I am having a hard time finding how to do it using the OleDb in VB.net.
Dim ws As Workspace, db As Database
Dim qy As QueryDef
db.QueryDefs.Delete ("WISE QUERY")
[Code].....
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Dec 6, 2011
Dim Conx As String
Dim DBx As String
Conx = "Provider=Microsoft.ACE.OLEDB.12.0; "
[Code]....
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Oct 1, 2011
what happens is i have a weekly salary table and once a week an administrator computes the salaries and it will be saved there, i want the delete code to delete the already saved record with the same Emp_ID as what i'm trying to save. my problem is i don't think the code i put deletes the record because it will still tell me that there is already an Emp_ID the same with what i'm trying to save..
so far this is my code..
Dim cnn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source = C:UsersFlorieDocumentsVisual Studio 2008ProjectsPayroll SystemPayroll Systemobjx86DebugPayroll_MaryRoseAn.accdb")
Dim cmd As New OleDbCommand
[Code].....
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Oct 18, 2011
I have some variables in my main Form, but I want them in all my other forms, how can I make them kinda global or something?
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Apr 27, 2011
I have a form with textbox controls that are bound to the database. I have a bindingnavigator within the form, when i use the save & delete buttons on the bindingnavigator toolbar they seem to work but when i check my db nothing has changed. I have tried to work around this problem by updating the saveitem code using the code below.[code]
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Mar 5, 2010
What's the proper way to declare variables in a class? I've been doing something like:
'in a class
public shared teststring As String = "first"
'on a code behind
[Code]....
with shared variables loading a second window or reloading the page (without clicking the button) renders the hello world string. so how do I declare variables in a class but make it per instance?
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Sep 23, 2011
Background: I am working on an ASP.net project that basically fills out a form from user input. The generated form (for reasons which I have no control over) must be a JPEG or TIFF. So the user fills out the web form, which takes all of the input values and meges them into a blank image (jpeg) of the form. Using System.Drawing, it merges all of the text onto the form at designated Points. The points are defined as variables which are modified at runtime to compensate for the resolution of the image (in case it get modified/re-generated at a different dpi). All of this is working fine.
Problem: Currently I have a Sub that determines the dpi of the master image, then adjusts the Points accordingly. However, there are ~50 variables that have to be adjusted. So currently I have the Sub go thru each point variable and manually adjust the X & Y values. I have been working on a Sub that will iterate thru all of the Point variables and do adjustment. Here's a functional sample of what I have working:Imports System.Drawing
Partial Class test Inherits System.Web.UI.Page
[Code]...
This works...sort of. It allows me to grab each variable and modify it, but only in the instance. The original variable in the class is unchanged. Which means that when the program gets to the point where it's drawing text to the image, the points are unmodified. my basic question is: Is it possible to modify the original variable using this sort of process? If not, is the best way to use these modified values to declare the new class instance at a global level, then have the Sub that draws the text use the instance versions of the variables?
I realize that I could define all of the points in an array which would be easy to loop thru and update, but I've named each point variable something meaningful to correspond to the related text to be drawn.
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Apr 6, 2010
I used the wizard to create a datagridview and then binded a grid to an access table.Data show up fine..But I can't dete records via the bindingnavigator.Hit the delete button then hit the save button ?Data does not get updated in the backend database.My properties are set to true for adding and deleting.
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Dec 16, 2010
I'm trying to create a generic Controller Class for generic events. But these these events still need to access their class variable. So my idea is to create the Base Controller Class with a ModelBaseclass variable as _ClassVar, which is inherited by all of the other class Controller classes will derive from. But I want the derived controller classes to override the _ClassVar with whichever one they need.
I want to do this, so the ControllerBaseClass can have all the generic functions that all the Derived Classes would use.
Model :
Public Class ModelBaseClass
Public Overridable Function Foo() As String
Return "Name"
[Code].....
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Jan 28, 2009
I have a class file, myClass.vb. Here is an example of the file:
Private _active As Integer
Private _categoryID As Integer
Property active() As Integer
[code]....
when I want to assign a value to the variables in the class file, should I assign them like what I have in line 24, and 25 or line 28 amd 29? how I assign the variables in terms of performance?
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Feb 25, 2010
when using variables in object names.I have a Public class which is called "Tank".In that class, there is a public property called "direction" of an integer type.I keep getting the error:
"Tank is a type and cannot be used as an expression"What I'm doing wrong here ?
Public Class mainroutines()
Create Instances of tank
Private Tank1 As New Tank()[code]....
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Jul 7, 2009
In the code below, the namespace is called "Navigation" which I think is correct. Then I have a class called "Heading", which by definition is the direction a person/vehicle is truly pointing towards. I think that is also named correctly. In the code below, I have four things I have named:
_WhatToName1, WhatToName2, WhatToName3, and WhatToName4.
The value that gets passed in and stored is a double between 0 and 360 -- essentially the degree value from a circle. For WhatToName3 and WhatToName4, I have seen a lot of places that just use "value" as the name. Is that standard?
Namespace Navigation
Public Class Heading
Private _WhatToName1 As Double
Public Sub New(ByVal WhatToName3 As Double)
Me.WhatToName2 = WhatToName3
[Code] .....
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Aug 20, 2010
Ok so here's the story. I have an array of Assemblies which are initiated by [Assembly].LoadFrom() that load a number of DLL's. Upon initialising, a method called InitMain (from the DLL!) is called, which sets a number of variables outside of this method, like here:
Public Class Example
Dim C As Integer = 0
Public Sub InitMain()
C = 50
End Sub
[Code]...
If I call the method Test using that same array of Assemblies somewhere later in the main application (like pressing a button or something to trigger it), it will pop up a messagebox with that says: "C = 0"Why is this? Is it fixable without any odd workarounds?
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