I have written a VB.NET 2.0 code and in my code i am calling class.Showdialog and for that i am getting thread exception. I have mentioned the call stack of the exception. Can any one help me out to resolve this issue. [code]
View 5 RepliesIt is possible to catch an exception and throw a new exception which wraps the first exception as an inner exception: [URL] Also, if I call a function and it throws a certain error, but I catch it, will the calling code's catch handler execute? If so, and it is of a higher exception type, is this not wrapping the exception? eg I can throw exception ex of type IndexOutOfRange, log it but rethrow, catch a higher up exception and do something, or I can throw a new exception and wrap an inner exception like:
View 1 Replieswhere I am starting another thread which opens a form. Succinctly, it is an animated "Please wait.. processing" type of form. The issue is that I want to make this form a child form of the parent (main thread or main GUI) when I open it.The issue is that I prefer to use frmProcessing.ShowDialog(frmMain) instead of just frmProcessing.Show, because of form disappearing issues. It, of course, gives me an error of illegal cross thread operation. My question is, how do I perform frmProcessing.ShowDialog(frmMain) to show from within another thread, that the newly opened form is actually a child of the main thread. Is there a better way for me to make a small processing form telling the user to be patient while background processes are working? [code]
View 2 Replies[code] For some reason, and I don't know why. The same CustomSplashScreen that had a handle for UpdateText shows to not have a handle when I call .Close().So basically it would show the splashscreen and update the text, but the form would be left opened and not closed like it is supposed to be.
View 2 RepliesI ran into an interesting dilemna today. I have a function that handles information and checks for duplicate values, then returns the next number that is not a duplicate. So, I have something like this:
Public Function GetNextNonDuplicateNumber(NumberToCheck as Long) as Long
//the non-duplicate the function will return
Dim NonDuplicate as Long
'duplicate
If CheckForDuplicate(NumberToCheck) = True Then
Throw New DuplicateException()
[Code] .....
As you can see, I want to handle the exception specifically, but I also want to throw it when I'm done because I want to alert other code outside the function. The problem is that simply throwing it exits out of the function with a null value.
1) How is ON ERROR GOTO -1 used? I don't understand the help text.
2) ON ERROR seems to be deprecated. What is the recommended Try...Catch replacement for ON ERROR RESUME NEXT. ie. where I have a series of commands, any of which may throw an exception, and I want to ignore all exceptions yet attempt every command?
so i have a Method that is going to made Thread Safe. can i have something like this in the Method:
Public Class Q Private Shared ASD As New MyException("") Public Sub W Throw ASD if multiple threads attempt to throw the Shared exception ASD, will there be an error in the catching part? The alternative of course is to: Throw New ASD but i'm just checking to see if the first way is thread safe
Assume you have the following code:
Instead of doing:
Try
'
[code].....
while my first .net steps I want to understand and test the Method
Private Sub MyApplication_UnhandeledException in ApplicationEvents.vb.
But if I throw an exception the IDE stops and says "unhandled exception" and gives solution tips.
Is it possible to switch off those exception warnings and run through the unhandeled exception handling in ApplicationEvents.vb ?
I'm not getting any errors, or anything I just forgot how to do error checking in the "set" portion of properties
I have 3 Classes, my frmMain,Sales and a Validator Class
Code for the Validator Class:
CODE:
Code for my Sales Class:
CODE:
I need to Throw an Excepton when the Sales price is Zero or negitive and when the trade in allowance is negtive I'm not quite sure how to do that in the Object Oriented Manner.
I am trying to show a dialog from one of my WPF view model commands however when i call ShowDialog() it throws a System.ArgumentException?
Here is my code:
Public ReadOnly Property OpenParser As ICommand
Get
Return New RelayCommand(Sub(param As Object) OpenParserExecute(DirectCast(param, Frame)))
End Get
[code]....
If I have an existing exception object (I'm not in a catch block, I just happen to have been given an exception object), is there any way (re)throw it while preserving it's stack trace?
The context for asking is that I'm writing a RunWorkerCompleted handler. If an error happened while running the background task, then this will have shown up in the Error property of the RunWorkerCompletedEventArgs. To keep the code simple I want to use the same error handling code to trap this, or any error that happens later during the handler. That means I need code like this:
Private Sub OnDone(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)
[Code]...
I don't think that using an InnerException here (ie. saying something like Throw new Exception(ex)) will work because then I have the problem that my Catch block has no way of knowing whether the exception it's supposed to be handling is the outer one or an inner one. StackOverflow seems to have various similar questions, but I've not found anything that describes this particular situation.
When I print to the printer, using the PrintDocument, I want it to be able to throw an exception if there is a problem. Currently, if I print to a printer that has a jam, is offline, or doesn't even exist, VB still thinks it printed fine. I never get an error. How can I have the printer report back to my program so that if I print to a printer that doesn't even exist, it wont let me do it? I just tried adding a LPT1 printer to my computer (and there is no local printer). I called it some random printer and installed some random driver. Then used my program to print to that printer and never got an error.
View 1 RepliesI want to throw error, if i used methods from this namespace System.IO
For example,
If i write File.Delete("TempPath") , i have to throw undefined Method..
Having problems with null dates in a mysql table. Have eventually found out that I can store a 'null' date in mysql as "0000-00-00" and I can run the 'insert' command to add a record to the mysql table. When I check on mysql workbench I can see the row has been inserted correctly and the date shows as "0000-00-00".However...When I try to load the table into a datagridview, I get an error = mysql Conversion Exception was unhandled = "Unable to convert MySQL date/time value to System.DateTime".
View 4 RepliesI am getting this exception: Cross-thread operation not valid: Control 'TextBoxOutput' accessed from a thread other than the thread it was created on. in a VB 2008 Windows Forms application that I havent specifically made multi-threaded. I have create a sub called Out() like this:
Private Sub Out(ByVal inString As String)
Me.TextBoxOutput.Text += (Me.TextBoxOutput.Text & inString & vbNewLine)
Me.TextBoxOutput.SelectionStart = Me.TextBoxOutput.Text.Length
Me.TextBoxOutput.ScrollToCaret()
End Sub
and I call it from various events to log messages I am getting from my pbx, which I use a third party open source dll to access. The interesting thing to me is that if I run the deployed application (ie, not in the VS IDE) I do not get any exceptions, it's only from within the IDE.if I add the line: Control.CheckForIllegalCrossThreadCalls = False to the form's constructor, the exceptions stop, but a) this seems like a hacky way to get around the issue and b) the application seems to hang sometimes when I have it set this way.
As we know, one STA UI thread creats the controls only canbe accessed in the UI thread in Winform application. And we need to call control.invoke or begininvoke to run the code in the background thread.
Yes, below code in VB.Net , VS 2010 Winform project can throw the exception "Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on."
[Code]...
I have below program that throw exception. Do you know how to fix??
Dim conn As New SqlCeConnection
conn.ConnectionString = "Data Source=" & Dir & StockTakeFile & ";Persist Security Info=False"
conn.Open()
Dim cmd As New SqlCeCommand("select * from TableStockTake", conn)
Dim reader As SqlCeDataReader
reader = cmd.ExecuteReader()
[Code]...
If I throw an exception from within a catch, does the finally (from the catch) still execute? i.e.
Try
..some code with an exception in it...
catch ex as Exception
throw new SpecialException("blah blah" & ex.Message, ex)
[code]....
I'm writing some code in which I need to use my own HttpResponse object to capture the output from a method on another object that takes an HttpResponse as a parameter. The problem is, this other object (which I cannot modify) calls HttpResponse.End(), which causes an "Object reference not set to an instance of an object" exception to be thrown. What can I do about this?
Dim myStringbuilder As New StringBuilder
Dim myStringWriter As New IO.StringWriter(myStringbuilder)
Dim myResponse As New Web.HttpResponse(myStringWriter)
[code].....
I have a lot of shortlived threads that updates my program, by events fired from a socket connection. My problem is I don't know how to debug this, like how to get the proper information on where in the code the exceptions occur. Because I get for example an exception like below, and this will just be the print in the Immidiate Window. There is no pop-up window, and it does not highlight any line in the code or show even what method it was in.
A first chance exception of type 'System.InvalidOperationException' occurred in System.Core.dll
A first chance exception of type 'System.Threading.ThreadAbortException' occurred in mscorlib.dll
A first chance exception of type 'System.Threading.ThreadAbortException' occurred in Krs.Ats.IBNet.dll
How do you catch an exception generated on another thread
View 12 RepliesI am using VB.net and I am getting this error only in debugging mode.Current thread must be set to single thread apartment (STA) mode before OLE calls can be made. Ensure that your Main function has STAThreadAttribute marked on it. This exception is only raised if a debugger is attached to the process.
View 1 RepliesI'm having a small issue; I start a process and when that process exits, I raise an event which removes a control from my form.It all works perfectly until the part where I want to remove a control from my form. Visual Studio gives me a cross-thread exception even though I'm programming single threaded.
View 6 RepliesI'm working on a web application that uses the web browser control to get and set info from my website. The content on the site is pulled from different pages and the data the application stores becomes really huge so i used a background worker to do the work and keep the form responsive. On each loop i call to get the webbrowser's inner html so i can sort through it and grab what i need and it works; but only the first time!? After i call it the first time and try to call it again to update the variables the function hangs and then the console shows me a Thread Abort Exception, The try statement i used to contain it doesn't fire off an exception. When i debug the program and i get to that function, it hangs and then just stops working.
The function that loops:
vb.net
Dim ids As String = GrabIDs()
Dim IDCount As Long = ids.Split(CChar(",")).Length - 1
Do Until IDCount = 0
[Code]....
I am using VS 2008 Pro and my ? is, I am trying to add lines to a listbox and keep getting Cross-Thread Operation not Valid exception. The code I am using was downloaded from codeproject. When I run this app, it works fine. I added it to my app and this is where the cross-threading problem occurs.[code]I am trying to convert mp3 files to .wav files. With the line above it works. With it out, the exception is thrown.
View 5 RepliesI have a windows form that gets data from a scale via the serial port. Since I need the operator to be able to cancel the process I do the get data process on a second thread. The data collection process gets multiple readings from the scale one at a time. The form has a label that needs to be updated with information specific to each reading.
I call the method to get the data from the scale with this code.
Dim ad As New readALine(AddressOf thisScale.readALine)
Dim ac As New AsyncCallback(AddressOf Me.GetDataCallback)
Dim iar As IAsyncResult = ad.BeginInvoke("", ac, ad)
The delegate for the readALine method is defined in the UI code.
Delegate Function readALine(ByVal toSend As String) As String
The GetDataCallback method:
Private Sub GetDataCallback(ByVal ia As IAsyncResult)
.
.
.
lblInstructions.Text = _thisMeasure.dt.Rows(_currRow - 1).Item("cnt") & ":"
lblInstructions.Refresh()
.
.
.
End Sub
I get the exception on the "lblInstructions.Text =" statement. I thought the GetDataCallback method was part of the UI thread so don't understand why I'm getting the exception. I know this could probably be rewritten using a BackgroundWorker and it's appropriate events but for now would like to understand why this isn't working as expected. The application was written originally in VS2003 and just recently upgraded to VS2008.
I am trying to implement a solution for updating form controls without using a delegate.
Imports System.ComponentModel
Imports System.Runtime.CompilerServices
Public Module MyInvoke
[code]....
I get a cross threading error as though i didnt even use this method:Cross-thread operation not valid: Control 'ComboBox1' accessed from a thread other than the thread it was created on.
I have created a class for Socket reads so I can create sockets on command. Due to performing a socket read, the program will freeze waiting for incoming data due to being on a single thread. So I created a separate thread for the reading of the sock and attempt to invoke an event to prevent multi-threading errors.
But I am getting an error when trying to Invoke: "Invoke or BeginInvoke cannot be called on a control until the window handle has been created."
How can I fix this or is there a better way to read a sock without freezing the thread?
Class for Sockets:
Option Explicit On
Option Strict On
Imports System.Text
[CODE]...
Calling form code example:
Private WithEvents Socks As clsSock
Private Sub Sock_Connected(ByVal state As String) Handles Socks.Connected
MsgBox("Connected - " & state)
[CODE]...
I tried to update the button text on a form from a backgroundworker.do_work event, and it failed, with the usual cross-thread exception message.However, by pure chance, I also tried to update text in a system.windows.form.toolstripstatuslabel also from this backgroundworker.do_work event, and it DOES work. Question: why is this? Is it perhaps because theres some kind of implicit shared behaviour with system.windows.form.toolstripstatuslabel?
View 4 Replies