How To Keep Thread When Using A Try...catch Statement
May 28, 2012My.Computer.Network.DownloadFile(URL, Path, ... etc.)
Catch
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Button_click Event Will Not Stop Execute After Error Catch Using Try - Catch Statement
Apr 1, 2011i have problem when i click a ADD button, there is one null value in the textbox .. so the try catch statemnt is to catch that null value error but after that the catch is success but the button click never stop excute the statemnt till the end of the button event.
View 6 RepliesExceptions - Can The "Throw" Statement Exist In A Block With No Try/catch Statement
Oct 5, 2009how to use them then before, but am still a little confused with a few aspects. Here goes:
1.) Lets say you have a method that checks for a certain condition(s) and if it fails Throws an exception. Does it have to be in a try/catch block? Meaning can the "Throw" statement exist in a block with no try/catch statement?
2.) Now lets say we have a method that has a try catch block and in it there is a throw statement. When the throw statement is executed does it first try to find an appropriate catch block in the same method or does it immediately go back to the calling method without looking at the catch statements in the current method where the exception was thrown?
3.) I created a custom exception class that inherits from ApplicationException. Next I created a method which has a catch block that catches this type of exception and does some action. Is the System(i.e CLR) smart enough to throw an exception of this type, or does it only throw exceptions from SystemException?
4.) I know that some people are more liberal in their use of exceptions and others use it more sparingly when truly strange stuff happen like the DB going down. I am writing code where I am getting some info back from the database, converting it and then storing it. Sometimes there might be data that comes back from the database and other times the field is empty and the Null value comes back. Therefore in the instances where Null comes back from the database I should not convert the value to anything, since I will get an error. What should I do in this situation? Should I let the CLR throw the exception when it goes to convert the Null value or should I check for the Null value and if it exists not convert?
5.) In general when I throw exceptions, is it sensible to only throw exceptions of the type Application Exception or are there instances where the programmer throws exceptions of the type SystemException?
Catch An Exception Generated On Another Thread?
Jan 15, 2011How do you catch an exception generated on another thread
View 12 RepliesWhat Is The Point Of This Catch Statement
Sep 22, 2009I seen this in legacy code. What, if any, is the purpose of a single Throw within a Catch?
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Is the outcome the same as if the original error was not caught? Would you use a Throw statement w/o parameters to re-throw the original error, typically after performing some action first?
VS 2008 How To Use Try Catch Finally Statement
Jun 15, 2009i want to know how to use try catch finally statement.i want to catch this error Violation of PRIMARY KEY constraint 'XPKemployee'. Cannot insert duplicate key in object 'dbo.employee'.
View 4 RepliesVS 2008 How To Use Try..Catch...Finally Statement
Mar 4, 2011i have this problem about the try,catch,finally statement... i don't know how to use it..i have my converter program here and this should be type by a letter 'cause if you do it will go lag or hang...i try VERIFY button to make sure if it's a letter or number but my teacher said it's not counted...
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If ComboBox1.Text = "Pounds To Kilo" Then
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Thread Safe To Throw And Catch Shared Exceptions?
Jan 25, 2010so 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
Determine Error Type In Try Catch Statement
Sep 24, 2009I'm interested in having a generic 'Try Catch' clause, with some case statements or if/than statements within the Catch part so that I can handle different error types differently. some way to get ex.Errorcode or ex.ErrorType that differentiates the different errors to a unique value.
How can this be done?
Try
'some code taht will throw an error'
Catch ex AS Exception
If ex.ErrorCode = 20 then
' Do something'
[Code].....
Regression Testing - Try Catch In Assert Statement
Jan 20, 2009I am doing regression testing using NUnit, WatiN and VB.net. What I am doing is opening an IE page, selecting some data, making a registration and then on view registration page testing the registration by assertion. Any good way to use try and catch on every assert. i am using it because if some assert fails it will stop executing the rest of the statement and quits without running rest of the tests. Now I have put try and catch on every assert and writing the fail message in log file.
For instance If I am checking for some airline reservation booking. After creating a booking, On view Booking Summary Page I am testing weather it is displaying cancel booking button or not. For this I am using the following code:
Try Assert.IsTrue(_internetExplorer.Button(Find.ById(New Regex("CBooking"))).Exists)
Catch ex As Exception d_logger.LogResultTextFile("Cancel Button does not Exist", True, False) End Try
I am checking this by running this in a loop for no of bookings created. I want to keep running the test even if in one booking it wont finds the button but keep checking for other bookings.
Asp.net - .NET Button Control, OnClick Event: (Try, Catch Statement)?
Oct 31, 2011I have a button on a web page that I just need a little help with some extra code. I think I need a TRY, CATCH statement?, this is what I have so far: I have a simple web page that has a button which at the moment when pressed enables the user to add data to a DB table via a stored procedure.Once this button is pressed a pop up message box is displayed to let the user know the data has been passed. The user then needs to press the 'OK' button within this message box which then directs them to the home page of the site. This works fine.
The code for this is here:
Protected Sub btnAddRawData_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAddRawData.Click
'database conn, this is linked to the web config file .AppSettings
Using dbconnection As New SqlConnection(ConfigurationManager.AppSettings("dbconnection"))
[code]....
As I don't want the user to enter duplicate records in the database (This could be done by the user navigating back to the page where the btnAddRawData_Click is located and pressing it again.), I have created a UNIQUE INDEX named 'DupRecords' to stop the user from commiting this data more than once that day.When I run the web page now I get the following message in my browser:
Cannot insert duplicate key row in object 'dbo.GasRawData' with unique index 'DupRecords'.The statement has been terminated.The solution I think, is to add a TRY, CATCH statement into the btnAddRawData_Click code.
Set VS2008 To Break On An Error Inside A Try-catch Statement?
Feb 19, 2009One of the things I loved about VB6 is that you had the ability to tell the development environment to break on all errors regardless of what error handling you had set up. Is it possible to do the same thing in VS2008 so that the debugger will stop on any error even if it happens inside a try-catch statement?
View 4 RepliesTry / Catch Exception Handling Breaking INSERT Statement
Sep 12, 2010When trying to use Try/Catch in my code the INSERT statement does not work, but when I comment out the Try/Catch it works fine with no error. The section of my code is below:
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C# - Catch Events In Multi-threaded Application That Can Be Watched By Main Thread?
Dec 4, 2009I have a console application (VB.NET). When it is started, it spawns worker threads to find work in the database and do the task, then look for the next task (A workflow basically).
The problem that I have is that I have my Event Handler in the main thread that spawns the worker threads. Those workers, if they error, raise an event to a public delegate. However my main thread is not detecting these events, and I cannot figure out how to make it. My intention is to do all logging (text/database), email alerts, and restarting the worker to find another task that is not errored. (This will be expanded in the LogErrorMessage routine and such, for now I am just keeping it a simple Console.Writeline so that I can see if the method is being fired or not)
Here is the code around what I am trying to do:
Logger Class:
Public Delegate Sub LogDelegateError(ByVal Ex As Exception)
Public Class EventLogger
Public Event EventError As LogDelegateError
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Is Try / Catch / Finally Required With Using Statement In Order To Handle Exceptions
Jan 31, 2012I wonder how to use statement handles exceptions?Do I need to wrap the using statements with a Try/Cath/Finally clause in order to be sure that the SqlConnection object is closed and disposed even if the containing code throws an exception? [code]
View 3 RepliesStop All Threads Or Just The Thread That The Statement Is Executed In?
Dec 12, 2010I'm working with vb.net 3.5SP1 /VS2008. I'm familiar with windows threads from C++ but I didn't do it since the 90s.I have 5 threadpool calls (ThreadPool.QueueUserWorkItem) that do some complex work (they read info from different web pages, regular expressions, etc) and each updates different columns in a data-grid view. They pause for 1 second between each web read with thread.sleep (not to overload the server). My issue is that some of the threads do not complete. I get for example 3 results when I should have 8. Sometimes it works fine. This is an older 3.0Ghz HT machine, I want to test it on the lowest common denominator(and that is all I have ). I tried using Monitor.Enter(ListView1)it seems to help but it is hard to tell. I tried using the thread debug window but it is not really helpful, it seems do disappear during execution. If I remove the threads I always get my data. I'm wondering if something is being blocked? Is there a way to debug this?
Also, does thread.sleep(x) stop all threads or just the thread that the statement is executed in?
VS 2008 Try / Catch Statement - Error "Failure Sending Mail"
Feb 25, 2010I'm e-mailing a message from my application to myself, I don't quite understand how to do this, but I did think I had finally gotten it right -
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I've got that code in a try/catch statement and it shows me via a MsgBox the error "Failure sending mail".
DirectoryEntry Memory Leak - Gets A Out Of Memory Error In The Last Catch Statement?
Jan 11, 2012The follow code can be called about 6K times on the server it is run on then gets a out of memory error in the last catch statement. I don't see what is wrong with the code, it works well up until the out of memory..
Public Function AddUserToGroup(ByVal sSamAccountName As String, ByVal sGroupName As String) As Boolean
Try
Dim returnStatus As Boolean = True[code]......
Error - Catch Cannot Catch Type 'Microsoft.Office.Interop.Outlook.Exception'
Mar 25, 2011I have a program in VB.Net that receives mails from Outlook, extracts attachments and inserts the attachments into a table through a query. I would like to put the query/queries in a Try/Catch block, but cannot do so as Outlook exceptions cannot be caught, and it gives me an error, and unless I put a very specific exception, I cannot catch it. Is there a workaround?
Edit:
Try
Catch ex As Exception
End Try
Exception is underlined and when I hover on it, it says: "Catch cannot catch type 'Microsoft.Office.Interop.Outlook.Exception' because it is not in 'System.Exception' or a class that inherits from 'System.Exception'". This is affecting all my other code which I'd like to put into a Try/Catch block.
Restructure Try / Catch To Eliminate Error On Myreader.close Command In Catch Part?
Jun 19, 2012The following code causes a "Warning" that Variable is used before value assigned.How do I restructure this Try/catch to eliminate error on the myreader.close command in the Catch part? Code appears to work fine but I dont like Warnings. [code]
View 8 RepliesNested Try...Catches - If An Exception Occurs In The 2nd Sub's Try...Catch, Which Catch Gets Excecuted?
Mar 4, 2009I have this scenario: in a Sub I have a Try...Catch statement.Within that Try..Catch I call another sub.In that 2nd sub is also a Try...Catch.(see below for example).Now if an exception occurs in the 2nd sub's Try...Catch, which Catch gets excecuted? The 2nd one, the 1st one or both?
Private Sub sub1()
Try
..do stuff[code].....
If Throw An Exception From Within A Catch, Does The Finally (from The Catch) Still Execute
Jun 2, 2009If 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]....
VS 2010 Error - Cross-Thread Operation Not Valid: Control TbPlaca1 Accessed From A Thread Other Than The Thread It Was Created On
Aug 13, 2010In one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"
Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()
[code]....
The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".
Cross-thread Operation Not Valid: Control 'Panel1' Accessed From A Thread Other Than The Thread It Was Created On." ?
Nov 3, 2011This is the error message I am getting:
"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:
Panel1.Show()
Label1.Show()
Label2.Show()
why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.
Error - Cross-thread Operation Not Valid: Control 'txt1' Accessed From A Thread Other Than The Thread It Was Created On
Jul 21, 2009I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.
Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()
[code]....
I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)
Error : Cross-thread Operation Not Valid: Control 'l_users' Accessed From A Thread Other Than The Thread It Was Created On
Jun 21, 2012When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.
Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub
Threading Progress Bar In .net - Thread Operation Not Valid Control 'ProgressBar1' Accessed From A Thread Other Than The Thread It Was Created On
Feb 17, 2012Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.
I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes
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Waiting For Threads - Thread.join Suspend Execution Of Code On Calling Thread Until Spawned Thread Finishes Or Is Aborted
Sep 2, 2010My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...
With that in mind, I tried this:
For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)
[CODE]...
However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).
Cross-thread Operation Not Valid: Control 'Autocad' Accessed From A Thread Other Than The Thread It Was Created On
Jun 6, 2010I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.
Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class
My main class loads frmCad as well as CadApp.
Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub
When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.
Cross-thread Operation Not Valid: Control 'label2' Accessed From A Thread Other Than The Thread It Was Created On?
Feb 9, 2011My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.
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