Use Instance Or Form Name When Addressing Public Variables Between Forms?
Nov 17, 2009
In vb.net, you can address a public variable from another form using the form name along with the variable.
form2.show
form2.k = 3
However, if you use a form variable to show an instance of the form, you must use that variable name to address the public variable. Two instances of the same form are displayed in the following example. The public variable k is assigned a value of 3 only in the first instance of the form, the one from form2.show. frm.k can be used to assign a value to the other form.
dim frm as new form2
form2.show
frm.show
form2.k = 3
Assuming only one instance of the form is shown in the application, is it reliable to address a public variable using the form name (form2.k), or is it better to show the form with a form variable and use that to refer to the instance of the form (frm.k)? Would the same answer apply to a property as well as a public variable?
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Aug 25, 2010
I have a string on my main form called String1. When I open another form, I need access to this value. In the form I open, I have always done something like:Dim NewString as String = Main.String1
This has worked in the past. Well, I ended up renaming my forms (from Form1 to Main) in the property window and it now when I type the above code, it does not list Main as a form. Nothing that I renamed seems to exist now.
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Jan 31, 2009
my problem is that i have an MDI Parent form. it has lots of child forms. on my MDI Form i have the toolbar buttons Add, Delete and Save.all or most of the child forms, i created a custom public procedure Sub AddNew, Sub Delete and Sub Save.what i'm trying to do is when i click the AddNew in the MDI Form, it will run the custom public Sub AddNew of the currently ActiveMDIForm. i have tried...
DirectCast(Me.ActiveMdiChild, Form2.AddNew()
but i'm getting an error "Unable to cast object of type 'Form1' to type 'Form2'" if the currently ActiveMDIChild is not Form2.
[code].....
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May 7, 2012
I simply cannot refer to a control on a form from module code as in all other versions of VB. Here is the code that I mean:[code]The fact that this cannot seemingly be done without getting into looping through an array of controls, assigning the control to a general control variable etc. and much more guff is puzzling and is in my opinion an added complexity to Visual Basic. There must be a simple way to do this - I just want to refer to the value in a control, on a form, from a module.
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Aug 11, 2011
I would like to pass variables variables from one form to another but the thing is that there is no variable that is actually being passed. I have tried to use instanciation
Dim f2 as form2
f2=new form2()
f3.textbox1.text="Whatever I want to pass",
but this did not work
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Nov 13, 2010
I have a question that I hope to find a much more simpler solution to.I have two forms in my program which are named Main and Second. The Second form has several textboxs, buttons (some disabled) and comboboxes. When the Second form is opened via the Main form on the very first instance, everything works fine.
However, if I re-open the Second form after previously closing it, the disabled buttons are no longer disabled and the text controls and comboboxes show the previous values entered from the first instance which I do not want. How can I ensure that the Second form will be opened "clean" every time.
Currently I have to add instances to the onload event to do this to ensure that the form is cleared on the second instance.textbox1.text = ""textbox2.text = ""textbox3.text = ""button1.enabled = False
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Oct 4, 2011
I'm making a IM LAN Chat, and I don't want to limit it to a specific number of chats that can be open at any given time (By re-producing the forms and setting variables once a chat is open).
[Code]...
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Sep 23, 2011
I've created a 30 point wizard. Every step gathers between 1 and 3 variables. I've created a module and publicly declared the variables there. At the end of the wizard, one master form opens, gets all the variables, and displays them on one form. At this point calculations are run too which populates more variables. This works fine for one instance of the process.
the user may want to be running two instances of the wizard at once. Obviously, if the previous wizard is part complete and they start a new one, the variables are going to get crossed or replaced by the new wizard.Is there a way for the variables to be declared publicly but used in multiple instances?
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Jan 17, 2011
I have a variable declared at Public on a form. But when I try to access it in a module I get an error that its not declared.
[code]...
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Aug 21, 2009
I'm working through a book that does not provide a lot of example code and what it does provide is in C#. The book refs vs 2005 but I'm using vs2008. The author asks for the user to create a solution with two projects, one winforms and the other a class library (called DependentAssm). The class library is added as a reference to the winforms project In the class library, he asks one to create a new class called SayHelloComp. The project created a file called class1.vb, and a class called class1 which I renamed to SayHelloComp. I left the file name alone, that's ok right?
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Aug 21, 2011
Is there any way to make a class instance public?In my mainform I define an instance of a certain class and then later on in some other forms which appear I want to alter this class.I try and pass them through when creating new instances of these other forms and it tells me Error3<instance of the class I want> cannot expose type <the class> outside the project through class <the form I want to edit it with>Which I gather from documentation is about it defeating the purpose to have a private class suddenly be thrown aroudn.but then how do I make it public? I can't define it in the first place as public myXClass as XClass, it only accepts private.
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Feb 8, 2012
creating single instance form in MDI Application. How to check whether form's instance created or not?
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Dec 8, 2009
recently started converting our project from 1.1 to 2.0
It was fine with the following:
Public ghtAllAppMsgs As New Hashtable(300)
Now it is complaining to change to the following is this the right way:
Public ghtAllAppMsgs As New System.Collections.Hashtable(300)
This is under global.vb class file: here are the imports i already had in this file:
Imports Microsoft.Web.UI.WebControls
Imports Microsoft.Web.UI.WebControls.MultiPage
Imports System.Web
[Code]......
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Mar 10, 2012
This seems basic but here's my problem. I am trying to build my connect string as a public variable that will connect to either an express version of SQL Server or a non-express version. The app.config defines it as being express or not and is modified to the user's choosing when it is deployed using the a firstRun routine.
The problem is that even though I'm modifying the value of the variable SQLexpress when the app is initiated which in turn should modify the value of the variable g_strConnectionString it doesn't. The value of g_strConnectionString will always take on the initial value of SQLexpress. I know I can define 2 separate variables for the connection string but I'd prefer not to have to change all of the references throughout each of the various programs in this system as they all have the same issue.
So in the following load event I've traced it and when it sets globals.SQLexpress = "", I then look at the value of g_strConnectionString and it still contains "SQLEXPRESS". It seems I need to somehow force vb to refresh this variable after it's been changed.
[Code]...
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Mar 11, 2010
I am a little new to .NET Developing, and have learned a great deal recently, but I'm stuck with something. I come from an ASP Background, I'm trying to subtract 2 variables, but they don't seem to 'see' one another.
[Code]...
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Mar 30, 2011
I have a MDI application and a very complicated class there which populates its properties from a dataset derived from an external database. Each form, including child forms have to be able to access that class and use its properties thorughout the whole session.I don't know where to 'preserve' these property values within the application. I kmow many books etc. suggest not to use public variables but I really can't find a way to solve this other than to use a public variable (which is a list(of my custom class) in this case.
I have a separate class called PublicItems.vb and declared there my public variable as
Public Shared secuniverse As List(Of myCustomClass)Is there something wrong with the syntax because if I try to use the variable secuniverse in my main application class, I get the following exception:'sectoruniverse' is not declared. It may be inaccessible due to its protection level.
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Feb 15, 2012
I am using this example I found to learn how to load class files and access variables through them. This is in a file called Class1.vb in the App_Code folder (this is not an app project):
Imports Microsoft.VisualBasic
Public Class my_class
Public Shared Sub my_sub()
[Code]....
How could I access the vartest variable without using a session, since if this is accessed by multiple functions at the same time the variable can be overwritten I assume. Is it possible to go the other way, where a variable is sent to a class file?
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Feb 15, 2009
I have created a public shared subroutine in a class file in asp.net 2 (vb.net) web site app_folder.The subroutine retrives some values from a sql database via an sql query and assigns the datareader field values to several variables The problem is I can't seem to assign the variables from the subroutine to the variables and textbox controls in the asp.net page I am calling the subroutine from. The textbox text value just appear blank.By the way, if I response.write the variables in the subroutine they appear populated by the sql data reader.
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Apr 10, 2009
I am currently working on a project of "interpreting" C# into VB. The project involves adding images to a database, retrieving images from the database and presenting them in thumbnails. Right now I have the following Public Class with the Variable that needs to be assigned:
VB:
Imports System.Data
Imports System.Drawing
Imports System.IO
[code]....
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Apr 29, 2012
When and why do you declare variables in the Public Class Form1 section?
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Jan 2, 2012
I'm writing a new app and copying/pasting some lines from another one. In the new app, I get error when I use variables defined as public.
[Code]....
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Apr 6, 2009
I have a class inside a class.I need to expose the properties of the 2nd class to other classes, therefore it is public.However, I do not wish other classes to be able to create instances of this 2nd class, it should only be instantitated from its parent class.I thought I could resolve this issue by making the constructor of the 2nd class private, but this even prevents the parent class from instantiating its child class! How can I work around this, do I have to make the constructor public and allow anybody to create an instance of the class?
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Oct 18, 2011
I have a bunch of private variables I've typed out and I want to put all of my corresponding Public ReadOnly Properties in a bunch below them.Is there some way of copying ten lines of
Private _myVar As String
and pasting in ten sets of
Public Readonly Property MyVar As String
Get
Return _myVar[code]....
I'm currently copying the whole bunch of variable declarations, Find+Replacing Private _ into Public ReadOnly Property then going line-by-line expanding the definitions and writing return statements.how to avoid all this nonsense in the future, as I'm developing on a virtual terminal server, and the input lag on my little copy/paste/type operations on the code is driving me up the wall.
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Jan 13, 2011
I'd like to get a more refined programming style and I was wondering if any of you might give me a hand...(How to declare public variables, constants, functions...in a proper way),is there any useful link or pdf document I could have a look in order to improve my style?
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Jul 22, 2009
give me a good resource that explains the difference between a Private, Public, Shared Functions/Sub/Variables? I normally use Public for Subs/Functions inside of Modules I call from other parts of the program. But I'd like to get more of an understanding of how and when to use them. I want as little as impact to a system that is running my programs as possible, so i guess the key here is I'm trying to just get more proficient in my coding.
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Apr 15, 2009
I have the following code:
Public Function StoreFields()
Dim Lockbox, Cash_Deposit_Date, Batch_Number
Lockbox = Xdocument.DOM.selectSingleNode("dfs:myFields/dfs:dataFields/d:tbl_GC100/@Lockbox").Text
[code].....
I have tested the variables in the Functions and the are correct.
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Nov 11, 2009
I have these list of RS-232 strings declared in my public class
Public Class TouchInterface
Dim WatchTVbtnCmd As String = "rs232command1"
Dim VolUpbtnCmd As String = "rs232command2"
Dim VolDownbtnCmd As String = "rs232command3"
Dim SystemOffbtnCmd As String = "rs232command4"
Dim RadiobtnCmd As String = "rs232command5"
Dim MusicbtnCmd As String = "rs232command6"
I then have this private sub. For the sake of this thread, what I would like to do is get the name of the label that was clicked which in the code below is already done, convert it to string (not sure if this needs to be done), this is also done in the code below. Next I want to compare the labelnamestring to all the variables in the public class to find out which one it is equal to and then disply that variable which should be my rs232 string in the message box. I have also added "Cmd" to the variable names above so I also need to work out how to add the text "Cmd" to the string to properly compare.
Private Sub Musicbtn_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles WatchTvbtn.Click, VolUpbtn.Click, VolDownbtn.Click, SystemOffbtn.Click, Radiobtn.Click, Musicbtn.Click, GardenVolUpbtn.Click, GardenVolDownbtn.Click, GardenRadiobtn.Click, GardenOffbtn.Click, GardenMusicbtn.Click, GardenMediaCenterbtn.Click
Dim labelname As Label = DirectCast(sender, Label)
[Code] .....
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Jun 26, 2011
I've got a program that runs from one Windows form, Form1, with stuff declared all in that class: public variables, public functions, subs, etc. I decided that the form was getting cluttered, so I added one button to bring up a new form, Form2, and I put some of the buttons & check boxes for testing over there, so that Form1 can be more visually clean. Problem: when I go to put the code for the tests into the buttons on Form2, none of the public variables or subs or functions that reside in Form1 are visible in Form2. What statement/s do I need to add (and where) so that the public "stuff" that's declared in the class for Form1 is visible within Form2, please?
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Dec 28, 2009
Passing data between forms without any public methods or properties on the forms. everything but the "Controller" class, which I would like you furnish. I just changed the title from "Intermediate" to "Beginner" This solution is an example of the Observer Pattern. The "Controller" class is the "observed" class, which in this case means it publishes events.
' File Definitions.vb
Public Delegate Sub MessageDelegate(ByVal sender As Object, ByVal e As MessageEventArgs)
Public Class MessageEventArgs : Inherits EventArgs
Public Message As String
[CODE]...
The program should initially display Form1, and Form2. Clicking of the button on either form will modify the Title Text of both forms. I think that you will find the final end result to be pretty neat, as it works with any number of open forms not just two. I think asking for the Controller class is easier than asking for the code in the forms. My solution for Controller class has 7 lines of content, 9 lines if you include Class, EndClass. A minimal solution could achieved with only 4 lines of content, but it would a textbook example of bad programming.
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Oct 17, 2009
Reflection on Objects is quite simple, not so seems to be on static things, like modules ( module1.vb ecc... )My question is HOW to gather information from VB Modules and then use them to copy values from a bunch of Public Variables on Module1 to same-named Variables on Module2.I've tried a thing like this by now :
ListBox1.Items.Clear()
Dim A As System.Reflection.Assembly = System.Reflection.Assembly.GetExecutingAssembly
[code]....
With GetMembers( NO FLAGS ) I manage to get list of members, but If I try to get only my-declared-memebrs ( with any combination of flags ) I get none.Finally, what i'd like to achieve is this :
1. Read all Public Variables form Module1.
2. For each Public Variable in Module1, put same value in Variable on Module2 which has same name and type.
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