I am in a VB programming class and I am having an issue with a program that I created. The focus of the program is creating a class to do calculations and sharing the data with a form.
The problem that I am having is with a certain piece of data that is shared between the class and form. To be more specific, it is two check boxes that each have their own variable as boolean, done as a true/false if checked/unchecked situation.
When I step through the program, somehow the values get changed entering the class for calculations. For example if it was true, false, it comes out as false, true when the class accesses the data. There are other variables and data types that get pulled but these are the only ones that are being altered.
I have an 8 bit digital output board used for device controlling. Each external device needs one bit and is controlled by a different application.I have written a class library and the class DigitalOutputPort (VB 2010) that envelopes the driver that manages the 8 bit port. Each device application uses this class, creating its own instance.
In order to set a bit of the digital output port, I have to write a byte to that port: this byte is the bit mask for all 8 bits together: to set HIGH the bit number 0 - 1 - 2, I have to write 7 on the port, to set HIGH all 8 bits, I have to write 256, and so on...
All works fine when only ONE application uses the class. But if two applications want to set its own bit on that port, I get problems because I do not know the current value of all bits set by other applications (the driver has not such function) and, of course, I cannot change one bit without changing all the other (if I do not know the current bit mask)
Normally this looks like a typical case of sharing data between two application and my first idea was to write the current value of the port in a file on the disc, where all application can access and read it. But it seems to be too much heavy for this simple problem. Moreover it could also creates performance ans reliability problem.
Then I though about using a shared field (property) in the class. A shared field preserves its value between all instances of a class: but is it also true between instances from different applications? I cannot find more info about this last point, I have to make same test.
A third way would be that I create just only ONE instance of the class DigitalOutputPort, one for all applications.The first application that needs it, create the object, all other applications will used the already created object.I like more than other this way, but I do not know if and how it can be done.
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.
I have done programs in the past with VB6 using the winsock control to receive data to be processed. I would like to do the same thing in vb.net but I am having problems. I have done numerous searches and consulted numerous books and articles, but haven't found the best approach for accomplishing the following.
I would like from 1 to 20 clients to be able to send a string to the server to be processed. It would be nice to if the clients could connect to same port and use async processes to open/accept more connections. One of the books (Visual Basic 2008 Recipes) has a recipe for creating "Multithreaded TCP Server that supports Asynchronous Communications".
I am trying to base my program off of that example and modify it for my application. The problem I am having is how to share data with the Main form and the classes that handle the communications. The TCP class has two classes contained in it. One class for listening for connection, beginning the accept client and the other class (clienthandler) for completing the connection and getting the data. I would to be able to get the data from the clienthandler class and post on the main form. I have trying to have a public property for the data but I think my confusion comes in because the clienthandler would be created new for every new client. The mainform would not know how many of the new clienthandlers were created etc.how get the data to the main form and clear the data when done. I have even considered putting data into MSMQ and having main form pull data out.
I know a little about threading and delegates, as well as socket programming. I'm working with a VB.NET-compatible SDK called TrueVision3D to create a small online game for me and my friends. The problem is that I cannot for the life of me figure out how to pass data from one thread to another. I've created 2 seperate threads on seperate forms.
The first thread is created on a form titled FrmLogin, and it contains all the socket code. I need to be able to update variables in the second thread, which mainly consists of a render loop. The second thread is created on a form titled FrmMain. I'm not quite sure if it matters what forms the threads are created on, I'm just trying to give as much information about the issue as I can. I've tried using delegates and events to pass information from the thread back to the form it was created on, which works fine, but how do I pass data to the second thread from the first?
I have developed it in one project, I now want to make it available to another project.
I have removed it from the project and moved the .vb & *.resx files to a directory for common modules.
I then go into my project select Add Existing item, select the .vb project and say Add as Link.
But now my form is missing - I just have the code.
I have two classes MyPanel & MyForm. MyForm was first, MyPanel second. It says they should be the other way round. When I swap them I get the message "to add componets to your class, drag them from the toolbox...."
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).
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]...
I have a PC with sql server 2005 express, my application works with it great, is it possible to install another copy of my application to a laptop that will move around and wont have access to the data all the time. trying to find something like SQLCE has(RDA)so it can see the data make changes and when it returns it submits all the changes. Is this possible and how can it be done.
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).
I am building a code library to be used by a 3rd party developer. Neither my code or the 3rd party have any UI controls involved. It's purpose is a combination of providing the ability to look up information from a database while at the same time polling it and throwing events when a set of conditions are met. Naturally the only way it's going to be responsive to the 3rd party library's commands is via multithreading since everything in a single thread stops once you start polling the database.
The sub I am using is part of an object that I create in the main thread and attempt to have it run via a thread, when a condition is met I have it update a property in that object, throw the event (or execute a callback in my latest attempt) and then attempt to have a simulator for the 3rd party control read the property.It's easy to setup the multithreading part, the hard part appears to be throwing the event so it is seen in the original thread and the data is available there. Any attempt to do this generates a cross thread error when the data is read.
I attempted to use delegates and calling methods asynchronously and using the callback function but still get cross threading errors.Is my only possiblity to use a background worker, using either the progress changed or runworker completed events? Even then am I going to be able to set the property in the function from one thread and read it in another?
I have a windows forms application with one exe and several dlls(Class libraries) in a single solution. The application uses common data that is used across all the dlls. I would like to load the data when the application is starting up and use the loaded data at various points in the dlls so that I do not have to load the common data again and again. How can I share the data loaded in main EXE across the DLLs?
I am in the main process using Activex EXE to create a sub-process, Activex EXE project inside a class module, class module which there are two instances of the event the equivalent of two threads, I defined the standard module module1.bas as public variable a, in two instances running at the same time, how the definition of public variables are not used, such as a private variable, each carrying out their respective variables of the same name! For example the implementation of a = a +1 statement, let the first instance of a run, a steady increase from 1; when executed when an instance of 2, a should be an instance of a value when the two began to increase, but also from two examples of 1,2 , ... began to increase.
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
I am converting some VB6 code which passed an unknown form object to a class, which then used the passed form object to reference the calling form and direct the data from the class as follows: The Called Class in the class clsGetRecord Public Function Execute(ByRef FRMForm as form) as booleanFRMForm.List1.Additem(SomeData)....Execute = SomeBool End Function The clsGetRecord is used by many different forms which receive data all have objects called List1 as: The Calling Form for the form frmThisFormPrivate function() as booleanDim objRecord as new clsGetRecordbRet = objRecord.Execute(frmThisForm) The passed form object which will receive dataEnd function. Is there any simple way to do this since the calling form object is unknown at design time?
I've been coding a Windows applicaton for the past seven months but there aren't a lot of "windows" in the application so I have a question on getting and returning data from forms. I display a form and the user makes a listbox selection then presses Ok. Normally I can proceed from there (in a class module) with values from the config file, but sometimes his selection will require me to ask for more information. So I want the class to display a form, pass control to it, then when the user hits OK on this form, return to the class. What is happening is the class continues with all its inline code and function calls and doesn't show the form until the end of its current function.
Dim flClientInputFile As New CFile Dim flPreparedOutputFile As New CFile Dim lRecordCount As Long Dim sProcessing As String Dim sTest As String Dim frmAbc As New frmAbc frmAbc.Show() frmAbc.Activate() x()
When I run and step through this code, I find I'm in x() before I even saw the form. x() needs the data the user has entered on frmAbc in order to continue.
I have written some functions that I have in a module. In one of the functions I would like to update a table that is in a dataset. I would like to do this with this function and not from a form class where the table could be bound. I need to call the function from various places in the application.
I have put this code in the global form Inherits System.Windows.Forms.Form. And then in the form that will inherit this from the global Inherits MenuStrip. "MenuStrip" is what the global form is called. But keep getting this error: Error1Base class 'MenuStrip' specified for class 'Lesson2' cannot be different from the base class 'System.Windows.Forms.Form' of one of its other partial types.
I've been creating short test apps repeatedly to try to understand some of the concepts in VB.NET.For the most part it has been illuminating.I read Bucky's .NET knowlegebase tutorial on passing objects as parameters to newly created forms. He shows how to create a new class that inherits from the base form class and define a New() method with parameters Extending the concept I thought about doing the same thing with a form that was created at design-time (In this case Form2).
I'm designing a small GUI Windows program that allow staff at a cinema to reserve seats for customers. There will be a total of 60 seats in the cinema. I have two classes in my program:-
1.) MainForm.vb - used for I/O actions and user interaction
2.) SeatManager.vb - used to hold and handle the background methods and functions that make the program work
Here is the code for my MainForm.vb class thusfar:-
Public Class MainForm Private Const m_totalNumberOfSeats As Integer = 60 Private m_seatManager As SeatManager
[Code]....
Basically, when the program opens, the lstReservations list in the MainForm class will be populated with a total of 60 (m_totalNumberOfSeats) entries to represent 60 seats. Each of these seats will contain the index number from the array m_nameList; this index number (+1) will represent the seat number and then in the lstReservations list, after the seat number, I'd like it to contain the respective entry from the m_nameList array. As all entries will be held in RAM, when the GUI is opened, all m_nameList array entries will be empty. As the user uses the program, they can highlight a row in the lstReservations list and then use the GUI textboxes to enter the customer's name which will then be populated into the respective array entry.
how to, when the GUI opens, ensure that the lstReservations list takes all of the blank entries from the m_nameList array and from there, I can highlight a row to carry out further methods on?
I'm trying to get the ATM Class to Instantiate on the Form class.
[code]...
ISSUE = " 'ThisATM' is used before it has been assigned a value. A Null reference exception could result at runtime"
The Other problem i am having is with a class in the program called CardReader. What am i supposed to type to let the code below be able to "read" the read function on the Form1?
I designed a class contains a form that have buttons. When i click any button this function runs
Public Sub BtnClick(ByVal sender As Object, ByVal e As EventArgs) result = CType(sender, Button).Text
[CODE]...
In another project I imported this class. I called the method that shows the form in my class. I need to store the 'result' variable in another variable in the new project. How can It be done.
I've got a pretty general question about the best practice in passing an object reference to a Form in VB.NET. My form is a dialog and I've created an overload ShowDialog method, where I pass an Object into it ByRef.
The trouble is, I want to be able to refer to that Object throughout my dialog Class and not just in the ShowDialog method. For instance, some of my Events for controls on the form, need to reference that object.
I know I could create a local Private variable in the Class and assign it to the passed value, and then use that value. However I'm thinking this isn't very efficient because it would (I believe) create a new copy of the Object (which is a complex, large class in itself).
What is the best way to access a value of a control within a form outside of the form class. I have a lot of functions defined in a module, one of these functions requires a series of values from controls in my main form such as the FolderBrowserDialog.SelectedPath element. I understand that these cannot be accessed in the format form.FolderBrowserDialog1.SelectedPath and that they need to be accessed using a delegate. This is the part I am stuck with.
How can I data scrub a collection of data? I am working with existing VB.NET code for a Windows Application that uses StreamWriter and Serializer to output an XML document of transaction data. Code below.
Private TransactionFile As ProjectSchema.TransactionFile Dim Serializer As New Xml.Serialization.XmlSerializer(GetType(ProjectSchema.TransactionFile)) Dim Writer As TextWriter Dim FilePath As String Writer = New StreamWriter(FilePath)
We are given a task to create a software that can share files between two computers without using lan (internet connection) but the presence of hardware devices can be used like cable, rs232, usb to usb or can be bluetooth to bluetooth file sharing. We searched about file sharing without using lan. The result was "socket programming". Is socket programming is applicable for vb.net? If yes, how is it program?
how to make projects which span multiple files and classes just fine. I've had big multi-file things working.I've been told explicity that my classes have to be private...yet at the same time I'm supposed to have a main method elsewhere and somehow call a menu in my main working file.I can get the program working perfectly when I do it in a logical manner but I just can't figure out how to call a private sub. I keep getting the error reference to a non-shared member requires an object reference.I've tried breaking the rules a bit and making one initial sub which is public, shared, etc... but all this does is delays the error until it tries to call its first private sub.
How can I have code-sharing between two projects without making a dll?
The issue is: I have a tool that syncs users & groups from LDAP to a database.
Now the tool is a windows service, but testing it as such is very difficult and time consuming.
Which is why I made a console application where I can test the LDAP syncing, and then just copy the respective sourcecode-files over to the service project.
But... keeping the common files in sync is a bit of a problem. I don't want to make a dll, because this probably creates me a problem with the 3rd project, a windows installer (for the service) where I have to use ExecutingAssembly path...
Is there a way to share the code without making a separate dll? Automagic statical linking, so to say ?
I'm doing my dev work on a Window 7 x64 machine, deploying to a Windows 2008 x32 server. At the moment I'm adding WCF services to some internal apps so that we can build smaller clients using net.tcp bindings that report to the user what the server is doing without running multiple instances of the server. To cut back on how much administration the apps will require, I tried enabling port sharing on my first server app. I'm using the app to self-host the WCF service so they can be easily moved from one server to another if necessary. Here's the code starting the server:
Dim _service_host As ServiceHost Dim active_server_address As Uri = New UriBuilder("net.tcp", "localhost", CInt(My.Settings.ServerPort)).Uri
[Code].....
I get the following error when I put a breakpoint at the last line: Unable to automatically step into the server. Connecting to the server machine 'nettcpportsharing' failed. The requested name is valid, but no data of the requested type was found. The Try...Catch block housing that code says the exception type is AddressAlreadyInUseException...but when I run netstat I don't see anything else listening on that address. There's no occurrence of 'nettcpportsharing' anywhere in my solution. I've checked to make sure that the Net.Tcp Port Sharing service is started.
