How To Have All Instances Of A Visible Concurrently
Jan 6, 2010
On a Form, I have button which, when clicked, creates an instance then Shows another Form. If this button is clicked a second time, a second instance of the other Form is created and displayed.However, the first instance then becomes invisble - it still has an occurence in the Task Bar, but is not visible on the display.
Using the Taskbar, one can select either instance of the Form and that instance displays correctly, but, only one instance is visible at any given time (the windows are at different locations on the display and are not hidden behind other windows). What needs to be done to have both instances visible at the same time?
The computer is running Windows 7 64 bit - I don't know if this problem is present in with other Windows versions or not). Here's the code that responds to button click:
Private Sub btnPermissions_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnPermissions.Click
Dim PermissionsObject As New Permissions
PermissionsObject.Show()
"Permissions" is the Name of the Form, which is in the same Visual Studio 2008 Project as the Form with the btnPermissions button.
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Jan 28, 2011
I can only run "so many" threads concurretnly, a notion which I have seen elsewhere.As a threading novoice, how can I determine the maximum number of threads to use? Or is this a "how long is a piece of string" question? What does it depends on? Hardware config or what?
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Oct 26, 2009
I'm writing something to download about 200 small (Around 200kb) files at a time. I pass the file urls off to a class which starts the downloads. The problem is that it'll start the download (Just creates a 0kb file) and then slowly downloads each file one by one, waiting for the next to complete despite this being a threaded class. This would be fine but after about a minute, windows removes all of the 0kb files and I'm stuck with only a few of the files being downloaded. How to get multiple files to be downloaded concurrently?
Imports System.Net
Imports System.IO
Public Class DownloadClass
Public downloadUrl As String
Public folderURL As String
[Code] .....
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Jan 28, 2009
I've got a panel - that's in a group box. All of this - with lots of other textboxes on labels - is in another panel (the big panel).I make the big panel visible and not visible based on selections made by the user.This small panel - that's in the group box. I cannot seem to make it appear.Even if I leave it VISIBLE at design time - the objects in it will not appear.Is there some kind of nesting problem that I'm not aware of!
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Jan 25, 2011
I have five menu items that i have created as a user control and placed on the master page. Now i want one of the menu items to be visible only for particular user role and not visible for others. Here is what I did. Its not working though.
[Code]...
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Jul 17, 2009
I'm having an odd problem when making a form visible and not visible and it not continuing to function. Here is what I have happening. I have a main form (frmMain) that is an MDIParent. On this form I have a menu to open a second form (frmCalculate) and populate a listview from Items in the database.
As I click or select items in the listview on frmCalculate the tag is read and data is pulled based on the id stored in that tag and fills in various fields on the form. This works great. However, I also have a context menu attached to the listview that allows me to perform a "what if" scenerio on the items I am calculating. When I select this menu, I hide the frmCalculate and open the frmWhatIf form where I can mess around with values on the item I had hilighted in the listview on frmCalculate. Nothing is pulled from or written back to the database here, all the information is filled in from fields on frmCalculate. It just allows me to look at rising costs and how they will affect my margins.... anyway.
If I then close frmWhatIf, it brings my frmCalculate back by setting its visible propery to true (never closed frmCalculate, just hid it). At this point if I click an item in the listview I get an exception for a null reference. IF however I never hide frmCalculate, I can open and close frmWhatIF without ever having an issue. Why do I lose the functionality to select items just by hiding and unhiding the form? As a test I added two menus to the toolbar on frmMain one called hide and one called show. I then opened frmCalculate with original menu item to populate the listview and selected a few items to test that it was working and then using the hide menu I made the form invisible and the show button to bring it back. This yielded the same exception so without even opening frmWhatIf the problem still occurs.
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May 18, 2011
I want to perform two hashing operations concurrently on a single file, without reading the file twice. Is there some way to share the FileStream between two synchronized hashing threads? For example:
Dim Stream As New IO.FileStream("...", IO.FileMode.Open)
Dim HashA, HashB As Byte()
Dim A = New System.Threading.Thread(Sub()
[code]....
Maybe some way of caching a stream? Trouble is, I don't want the entire file in memory at once (it could be many gigabytes in size) and I don't want the file read more than once, due to speed issues. I want the file cached only sufficiently to ensure that both threads can work.For example, suppose at some point in time, thread A had read 100k of the file, but thread B had only read 20k of the file. The portion of the file between 20k and 100k should be cached; but then progressively forgotten as thread B catches up. Then again, if thread B is too slow, we might still end up with hundreds of megabytes being cached.Maybe thread A should be made to wait while thread B catches up. Maybe the ReadByte() function of the stream should block for a while if one of the threads is too far behind?
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Dec 14, 2009
in my button click event i ececure
If BackgroundWorker4.IsBusy Then
BackgroundWorker1.CancelAsync()
End If[code]....
after proceess completed if press the button again.i got the following error msg
This BackgroundWorker is currently busy and cannot run multiple tasks concurrently.
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Jun 28, 2010
I have placed several PictureBox Images of different colored dots(which represent lights) on an image of a Christmas Tree. I can make the lights randomly flash using a randomGenerator and a Select case statement. However, the code is very long. There are 67 lights on this tree and the code is 71 pages long. There has to be an easier way to do this. So far I have tried the following with two images of lights just to see if it would work and it does not work:
Dim picLight(2) As
Boolean
For intX
[code]....
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Aug 18, 2009
Below is the exception code info. when I try to make form visible for the first time from another form then I get an exception code. something like 'a required variable not set'
Quote:
CODE:
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Oct 4, 2009
I wish to develop a program using DAO to access an .mdb database in a data navigational way and avoiding SQL. I have defined workspace, database and recordsets with a "DAO." prefix and referenced the Microsoft DAO Compatibility Library. When debugging, my statement setting the reference for the defined database name to the physical database, causes the following error - "Object reference not set to an instance of an object." It seems that the "New" keyword should be used to create an object instance but a statement such as "Public Db as New DAO.Database" is not allowed because DAO.Database is an interface not a class.
How do I create an instance of the object in this situation?
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Jul 25, 2011
I am trying to make a pretty complicated, layered program.I have my main form which creates an instance of another form (addValue and myAddValue). From myAddValue I then want to access a few other classes to do various verification and other bits of code.Here though I have a problem.With the form ContactDetails, it just can't seem to read myAddValue.txtName or the others.If I try and read AddValue normally it says about it not being able to access a non-shared member (Expected that this doesn't work, it was just an attempt at something different)How do I read myAddValue from a class which isn't the one that created and isn't the one that it is an instance of?
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Jan 3, 2011
Any best method of managing multiple SQL connections .net (VB). My application connects to four instances of SQL Server (2000, 2005, 2008, 2008R2) restoring databases, modifying data and taking backups. In addition to managing databases the app also has its own DB (on the 2008 instance) for storing various data. I'm using two methods to connect to the instances, SMO (For backups, restoring and retrieving information about the databases, size etc) and SqlClient for querying each database for many tasks such as updating fields and executing sql scripts.I have multiple forms for performing various tasks so there are many places I'm opening / closing connections.
Would it be best to maintain a persistent global connection to each instance from the application? (Two in total, one for SMO and the other for SqlClient) or open close a connection for each task I'm performing?) I'm not using LINK as I need the tasks to be as fast as possible. The connection string will differ on each connection (Based on Instance and Database being connected to) how would I manage this? A string in the config file for the applications database would make sense, as that would be static but the databases being worked on will vary with each connection. Currently I'm creating a connection for each instance within the main form:
Dim 2000Connection = New SqlConnection("Data Source=" & SQLServerName & _
"SQL2000;Initial Catalog=Master;User ID=sa;Password=P@ssw0rd;Pooling=True;")
Dim 2005Connection = New SqlConnection("Data Source=" & SQLServerName & _
"SQL2005;Initial Catalog=Master;User ID=sa;Password=P@ssw0rd;Pooling=True;")
Dim 2008Connection = New SqlConnection("Data Source=" & SQLServerName & _
"SQL2008;Initial Catalog=Master;User ID=sa;Password=P@ssw0rd;Pooling=True;")
[Code] .....
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Mar 7, 2012
Is bindingsource.count only used to give the total items in a list? I'm trying to prepare data for a pie chart, and need to count the instances of different items in a column (If there's a way that the Chart will do this itself, I've not been able to find it, it seems to need linked items and values). The bindingsource is already filtered and would prefer not to combine filters.Would it be best to loop through the rows of the column and count them 'manually' or is there a quicker way of doing this?Put it in a datagridview? Is it possible to use Aggregate Count on a bindingsource?
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Jun 5, 2011
i need to count the no of instances of a word in a string using vb.net i can do the usual way as my problem is a little different for eg i need to count the no of occurrences of -> in tree_ptr->sub.another->valu=3;
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May 1, 2011
The below Code is written inside the Timer Tick event. It works fine as long as the Time and Date are not same. When the Time and Date are same it only displays 1 message. How can I show multiple message for the same date and Time ? I think this can be done If I create different instances for a form. But I don't know how many same time and Date will be there in the database. So I can't do that.
Dim frm As New frmMessage
Dim nowDate As String = String.Format("{0:M/d/yyyy}", DateTime.Now)
Dim nowTime As String = String.Format("{0:h:mm tt}", DateTime.Now)
[Code]....
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Nov 21, 2006
I'm trying to create 3 instances of the the Workshop selector form for the 3 individuals that I have inthe listbox to appear when I first run the program.
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Jul 26, 2011
when i create a class ( ie ahuman ), i declare a object (ahuman) , i give it properties and with the properties i also can set the property ahuman , by creating the property ahuman (new) and set its variables, and declare its variables by declaring properties like weight, lenght, female or not.the problem for me is that i have multiple forms multiple class files , i cant oversee how to get track of all the new instances of classes.it is much easier to use pulbic shared properties to use a method in another class.
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Aug 5, 2010
(simplified) I have a button in form1 that creates an instance of a form2, fills some data unique to that instance, and shows it. This data should be unique. Any attempt to create an identical form2 should fail, and instead bring to front the matching form 2, but if the form 2 is filled with different data (representing a different person) than it should be created.
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Oct 15, 2009
I have an exe that runs from the server. The instances are shown on the server. So the questionis how can I get the following code to count the instances on the server.
HTML
Dim oProcess As Process
Dim nCount As Integer = 0
For Each oProcess In System.Diagnostics.Process.GetProcessesByName("MSTP")
nCount = nCount + 1
Next
(MSTP is the name of the application's exe.)
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Feb 6, 2011
I am able to create internet explorer instance by using SHDocVw.InternetExplorer, how to create instances for google chrome / mozilla fire fox / opera browsers.
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Jun 14, 2010
I am using the following code to create new instances of a form
Dim nfMainForm as New frmMainForm
nfMainForm .Show()
And when I open multiple instances of the form then I need to reference controls on specific instanced of the Form then I dont know how. i.e. I need something like
nfMainForm(0).lblFullName.Text
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Sep 13, 2010
If I create a console application for example with a class named "Person" I can create an object variable with a ceratin name only once. For example:
Module
Module1
Sub
[Code]....
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Mar 29, 2010
I have the following problem. (VB.Net 2008)I have created a class (myFirstClass). In this class there are a lot of calculations being made wich gets fired by events in that same class.Now i want that same class to be able to fire more instances of itself. However i noticed that each time i fire an event from a Sub the program waits till the event is finished before going to the next line of code. This is a problem since i want the event wich fires a new instance of the class to fire it and forget about it.
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Mar 3, 2010
I have two forms in my application. Form 1 is a listview that is populated with unique Customer IDs. When the user double click the listview on the particular Customer ID then it loads Form2. Form2 has many listviews within it such as a listview for the Customer telephone, another listview for their addresses etc and all the data presented in Form2 listviews are based on the Customer ID that the user clicked in Form1.
So here is my question...I want the user to be able to open Form2 with that particular details of the customer but also to go back to Form1 and double click another Customer ID and opens Form2 again (such as replicating Form2) with the other Customer details.So the moral of the story is i want the user to be able to have many instances of Form2 open each time they wish to view a different Customer ID without having to close Form2 down every time.
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Nov 6, 2009
Is it possible to look for all current instances of a specified object without specifically IDing each instance as it's created?
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May 12, 2009
can i do some thing like this in .net? and how?
Code:
dim object1 as new clsDatadim object2 as object
object2 = getobject("object1")
"getobject" function is my "needed function"
the purpose is to set object2 to have same memory address with object1 so if i change the properties of object2 then the properties of object1 also changes..
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Sep 13, 2010
I have a small "Clinic Application" that runs on two machines. (Receptionists & Doctors)
Same application is installed at both the computers, and they access the same SQL Server 2008 Data at a 3rd macine.
When the application is started, the local datasets are filled with the data from the 3rd machine (using tableadapter.fill).
Whenever the Receptionist adds a Patient in DataGrid,and saved it, it should show in Doctors DataGrid. and whenever Doctor adds something, the receptionists dataGrid should show it.
to accomplish this I have set a timer that keeps Filling datasets.
the task is successfully accomplished, but....
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Jan 16, 2011
I have a ComboBox that i am wanting to add all the SQL Server 2005 instance names to. The instances are located in the registry under:
HKEY_LOCAL_MACHINESOFTWAREMicrosoftMicrosoft SQL ServerInstance Names
I have tried to do this and I am not able to get it working. I haven't worked with the registry in a very long time.
This is what I currently have:
vb
'Enumerate the registry and add all SQL Server instances to cboServerName.
'HKEY_LOCAL_MACHINESOFTWAREMicrosoftMicrosoft SQL ServerInstance NamesSQL
Dim SQLInstanceRootKey As RegistryKey = _
[Code].....
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Oct 4, 2009
I am programming a chat like application using Tcp. Now I have a probem. I am going to have loads and loads of data being transferred so I will have to use 4 seperate ports.[code...]
My problem is for me to use a maximum of 4 ports all together transferring data from the client(s) to the server(s) I will need 4 clients and 4 servers. I need to open 4 instances of 4 clients. I was going to put a client in a form and then when the client is running it creates 4 instances of that form but than there would be too much confusion going on. I think there my be a way to use Classes instead of forms.
[code...]
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