Best Practice For Sharing Variables Across Forms?
Mar 27, 2011
I need to share variables across two forms in vb.net. One of them is the main form and the other is a child form.
Create a static/shared variable in one of the forms and access it in the other forms via:
Form1 frm = new Form1(); //creating object of parent to access shared variable
frm.a = "abc"; // passing value
Send an instance of the main form to the child form when creating the child form. The variables can then be accessed via a property function. Create global variables in a module. This seems like the easiest option, but I doubt it is the best option.I also read something about delegates and events, but I don't know how to implement this.
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Jun 16, 2010
i've almost completed my Yahtzee game except for the high scores function. I've got everything worked out except how to take the highscore variable from Form1, and share the data with Form 2
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Jan 27, 2011
If I got Dim myRect As Rectangle = New Rectangle(0,0,100,100)Is it necessary or just fine to later do this: myRect = Nothing Or it isn't necessary?IF it is necessary, are there other cases it isn't for my variables?
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Jan 12, 2012
When I want to maintain code readability and keep things neat. I would create temp variables . Below is one of my functions that uses it. Is it a bad practice? I would create temp variables cost more memory ?
Private sub test(byref transac as transaction , byref txntime as string )
Dim cmd as OracleCommand = nothing
Dim Adapter As OracleDataAdapter = nothing
Dim SQLStr As New StringBuilder
[Code] .....
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Jun 9, 2011
I am building an ASPX web site which has several pages and multiple users.I grab specific info about each user such as UserName, ID, etc. when they start a session and I need to retain this info and have access to it from each page (which has it's own class).I know i can create a global file and share variables publicly, but i need the variable values to be specific to the user, not the entire application.
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Feb 4, 2010
My question is, am I able to share a business logic layer seemlessly between the two presentation layers or is there anything I need to watch out for. I'd really like to not have any duplication of business logic, so any advice would be more than welcome.
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Nov 20, 2009
Starting to design an application and wondering if its ok to have only one form as the application which could hold up to 15 gridviews separated in tabs etc. with a navbar as navigation on the left. Is this too much or ok? Is it better to have one gridview per form? What is the norm?
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Dec 26, 2009
I have an application built that has several forms. I use an XML file to store settings data (mainly folder names for data output) and I need each form to be able to access and modify the data. I'd also like each form to access functions from a main form (such as file parsing functions). I have read articles about properties and inheritance but I need some guidance as this topic is pretty confusing.
[Code]...
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Nov 17, 2009
I am working with several RFID readers that perform different function in my vb.net program. Currently each reader port number is hard coded into the respective form. For example, reader 3 operates on COM1. However, this will be problematic when installing on different machines.
What I would like to do is have a "configuration" form where the user can select each reader and then select the COM port. Then all other code references these settings. What would be the best approach for this.
The only way I know to do it currently is to place this information in a small database and then have the forms reference that database, but it is a lot to do for such a seemingly trivial task.
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Apr 12, 2010
I have some icons and images that are stored as embedded resources in my form1.resx file. Is there any way I can access these resources from my Form2 without adding the icons as project resources?
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Sep 9, 2008
How do I share text between forms?I want a box to popup exactly like a input box, but needs to be multiline, Is there any east way to do this or will I have to create a second form?If so, how do I share the string between forms to then output in a textbox on 1st form?
Also, I have VB 2008 Standard, and I want to build an application for a handheld, Is it possible to build an application and then pass it over to someone who has the professional version to make it work on pocket pc? Or does the entire build have to be on pro already?It's a very simple program...
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Jan 25, 2012
I am trying to figure out how to seperate my business logic from my forms. This is my first attempt at doing this, but I would like to figure out how to handle events from multiple forms within a class. I have found myself routinely writing the same logic over and over in each form class and its time I figure out how to completly seperate out that logic in winforms so I can reuse the methods across all of my forms.
So basically I have this click event in form1:
Private Sub btnSubmit_Click(sender As System.Object, e As System.EventArgs) Handles btnSubmit.Click
[code].....
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Jul 31, 2009
When I declare a variable as public, shouldn't it be available in another form? I am trying to write a windows mobile prg with 12 static mileage points, form1 has the 12 buttons for start point, but when I call form2 with the destination points, my start variable value is not carried over. I intend to then assign a mileage based on the two points and write to file on mobile device. We support 12 schools, and I want my employees to track mileage easily.
Public Class main
Public start As String = "start"
Public dest As String = "dest"
Public miles As Decimal = 0
[Code] .....
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Sep 21, 2008
What I mean is that when I make queries on a Parent Form. Child forms can also retrieves the datatable /datarows from its parent form.
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Jul 23, 2010
if for example i have two private sub I declared a local variable on private sub a... is there a way that private sub b could use the variable created on private sub a? Im asking because im in a problem in my app were using global variable is not an option to make the long story short
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Sep 7, 2010
I'm starting to put in a database into my application, however I'm drawing a blank on how to share a database connection among the dozen or so different forms in my MDI application. I'm assuming this has to do with interfaces or something but I can't find any relevant examples anywhere. Can someone help me out? Ideally what I'd like is when the app is loaded up there is a call to a function in the forms loading area which establishes a single connection to the mdb, that I can then call via any form so I don't always have to open/close connections everytime I need to update the db?
Here's a basic example of the mdb database access code I've got working:
Dim dt As DataTable = New DataTable()
Dim OleDbTran As OleDbTransaction = Nothing
Using connJET As OleDbConnection = New OleDbConnection("connection string here...")
[code]....
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Feb 7, 2012
I have a form that can spawn a child form, something like:[code]I want to be able to launch multiple children. Unfortunately, I seem to be getting conflicts within the controls of the children. One button will run the other child's control, etc. They also seem to think that their class-level variables are accessible to each other. Private Shared variables like the following are conflicting (one form thinks it's seeing the other form's "mp3file" variable as their own):[code]How do I spawn children forms that keep their controls and data separate?
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Mar 31, 2010
I have two forms A and B. B is a child of A - i.e. I have a button on A that pops up form B. I want B to be able to access and change data (e.g. an instance of an object etc.) in A and also to call some function in A. At the same time I'd like to preserve the right to alter the data in A without opening B. I've achieved this using the following (i.e. by declaring the object and method as Friend):
Public Class frmA
Friend _data as Hashtable
Friend Sub GetData()
If _data IsNot Nothing Then
_data As New Hashtable
Is there anything inherently wrong with the what I've done and if so how can I achieve a similar result? (It seems to work - I can read, add to and change the values in the _data Hashtable from within form B and when B is closed the values persist i.e. I can access the changed values from within form A. I just dont know if its a horrible fudge).
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Sep 24, 2010
I am sharing databinding when opening a detail form a summary form. The data is shared fine. What I don't know is how to save any data that may have changed, or to create a new record.[code]...
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Jul 9, 2011
I have a very simple 2D array, it holds a list of song titles, their genre, and their runtime. frmMain loads the array from a text file and allows me to manipulate it and boil it down to a desired (implicitly sized) playlist. i want to THEN pass that playlist array to a second form, frmPlaylist The problem i'm running into....When frmPLaylist calls the Property from frmMain I receive an error that VB cannot convert the string value to a two dimensional array. Simplified...frmPlaylist is all locked and ready to receive a 2D array, but frmMain seems to only be sending a single string variable. on frmMain
Public ReadOnly Property PlaylistOut() As String
Get
Return mstrTimedPlaylist(,)
[code].....
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Sep 13, 2011
My question is in two parts:
1) I am writing an application for a touchscreen which will have several different Forms - each of which will be full-screen. What is the best way to achieve this? Hide/show each Form as the user navigates between screens? MDI Parent with multiple Child Forms becoming visible 'on top'? Or is there a more elegant solution?
2) I would also like a 'banner' on the top of each Form (or always visible on the top of the MDI Parent, etc) similar to a 'navigation frame' on a website. This banner will display a clock with the current time, and the current GPS location (meaning that a Timer will be used to get/set these values every 1000 milliseconds). I thought of using a UserControl for the banner - but if this is used on multiple Forms then I will end-up with multiple Timers all waiting 1000 milliseconds to update essentially the same information.
Is there a best practice for this type of scenario? - my thoughts so far are using the "Main" Form for Global Timers, etc - but then how do I update all Form clocks each second? (without iterating through all visible Forms... which seems messy).
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Dec 9, 2009
Am new to VB, can anyone tell me very simple how to share the MAIN Bindingsource with an detail form where i want to edit 1 record from the main datasource?
andreg
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Nov 19, 2007
I want to add a close button to a custom navigator. That's fine.
Now what if I want to use it on every form that I would create ? What is the best way (Is subclassing possible for this control in that case, ...) ? Any inspiring code somewhere even for another type of control ?
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Sep 11, 2009
I want 2 forms the main form which is form1.vb and the second form which is form2.vb to share the same value:
Dim Name As String="App1" so i can use it by simple doing that:
[Form1.vb]
Public Class Form1
[Code].....
Or it could be better if i didnt have to add a reference to the main form the string Name should be already declared in the second form so i could use just:
Textbox1.Text = Name
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Nov 27, 2009
I seem to be running into an issue. This may seem like a noob question (which it really is, I only have experience in vb6 from years ago) but what Im trying to do is pass a variable from one form to another. Ive tried telling the first form to set the value of the variable on the second form like so frmsecond.variable = "value" but that does not work. Ive tried placing a public variable in a module to do it, but again, no luck. The only way seem to be able to get it to work is the second form setting the variable by reading the value from the first form like so [code]The problem I have with that code is what if for some reason the selected line gets changed as the form is loading or something to that nature. It doesnt seem very secure.
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Aug 29, 2009
i am writing an application that will require users to provide login details. After the user has logd in a second form will be shown. Allowing the user to change his/her own details. What i have a problem is, im not able to pass the variables, containing username and password in the login form to the second form. Ive tried declaring the variables as Public but when the login form closes the variable are reset to zero.
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Sep 29, 2010
I'm sure this gets asked a lot, but I can't seem to find an answer for it. I want to have my Form2 change a variable in Form1.
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Jan 22, 2012
i need to call upon variables from different forms, in my first form i make a variable called "temp" i then use [code]to open the new form and hide the first, is there a way to access temp ( the variable declared in the first form) in the second form?
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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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Sep 6, 2009
I am having trouble passing variables between forms. Ive tried many methods but none seem to work. The first method I tried was to dim a public variable on the first form and call it on the second....no success
Form 1:
Public cliCode as string
cliCode = me.tbClientcCode.text
Form 2:
dim clientCode as string = form1.clicode
or
Form 2:
dim clientCode as string
On the Form2 load event....
clientCode = form1.clicode
With method 2 I created some classes on which form 1 loads and form2 access........
Public
Class frmClient
Private db As New ClientDataContext
Public clientInstance As New BusinessLogic.classClient
Public cliCode As String
[Code] .....
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