VS 2008 How To Use Try..Catch...Finally Statement
Mar 4, 2011
i 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
[code]....
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Jun 15, 2009
i 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'.
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Jan 31, 2012
I 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]
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Feb 17, 2010
I understand how try-catch works and how try-finally works, but I find myself using those (usually) in two completely different scenarios:
try-finally (or using in C# and VB) is mostly used around some medium-sized code block that uses some resource that needs to be disposed properly.
try-catch is mostly used either
around a single statement that can fail in a very specific way or (as a catch-all) at a very high level of the application, usually directly below some user interface action.
In my experience, cases where a try-catch-finally would be appropriate, i.e., where the block in which I want to catch some particular exception is exactly the same block in which I use some disposable resource, are extremely rare. Yet, the language designers of C#, VB and Java seem to consider this to be a highly common scenario; the VB designers even think about adding catch to using.
Or am I just overly pedantic with my restrictive use of try-catch?
EDIT: To clarify: My code usually looks like this (functions unrolled for clarity):
Try
do something
Aquire Resource (e.g. get DB connection)
Try
[Code]....
which just seems to make much more sense than putting any of the two catches on the same level as finally just to avoid indentation.
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Jun 2, 2009
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]....
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Nov 25, 2009
OK, I'd like to know the difference between the following two blocks of code:
Block A
Try
Something
[code].....
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Dec 27, 2010
Sometimes I do this and I've seen others doing it too:
VB:
Try
DontWannaCatchIt()
[code].....
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Oct 13, 2010
Is there some special way to catch exceptions in finally block ?
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Sep 15, 2009
I have a (begginner) question on VB.NET. Is this good code (I mean, is it "bullet proof")?. It seems to work, but I understand the Return is executed AFTER the Finally. So how does it call a method on an allready disposed of object?
[Code]...
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Mar 23, 2010
I've a class with a timer inside
Private tt As New System.Timers.Timer()
This timer is enabled in the New() of the class
Try
[code].....
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Sep 2, 2010
This is a followup question to this Should I stick with the Try/Catch/Finally construct, or go with the Using construct? Sample Code for Try/Catch/Finally:
[Code]...
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Jun 14, 2012
Suppose in VB.NET you have:
Try
Debug.Print("Trying...")
Catch ex as Exception
throw new Exception("Exception", ex)
Finally
Debug.Print("Finally...")
End Try
How would you write this using the "On Error Goto" construct? (please no questions asking why I would want to do this, just curious if it can be done).
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Apr 8, 2011
I have a SqlDataReader and I want to trap any exceptions with Try Catch Finally if the reader =cmd.ExecuteReader() statement fails. If this statement throws an exception do I need to close the reader? If so, where. Wherever I place the reader.close() statement I get an error that the reader has not been assigned a value yet.
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Jun 2, 2010
I am handling errors via my global.asax in this method:
Dim CurrentException As Exception
CurrentException = Server.GetLastError()
Dim LogFilePath As String = Server.MapPath("~/Error/" & DateTime.Now.ToString("dd-MM-yy.HH.mm") & ".txt")
Dim sw As System.IO.StreamWriter = New System.IO.StreamWriter(LogFilePath)
[code]....
In my code I currently have no other error handling. Should I still insert try, catch, finally blocks?
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Apr 1, 2011
i 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.
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Oct 5, 2009
how 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?
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Feb 25, 2010
I'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 -
[Code]...
I've got that code in a try/catch statement and it shows me via a MsgBox the error "Failure sending mail".
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May 28, 2012
My.Computer.Network.DownloadFile(URL, Path, ... etc.)
Catch
[code].....
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Sep 22, 2009
I seen this in legacy code. What, if any, is the purpose of a single Throw within a Catch?
[Code]...
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?
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Sep 24, 2009
I'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].....
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Jan 20, 2009
I 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.
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Oct 31, 2011
I 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.
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Feb 19, 2009
One 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?
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Sep 12, 2010
When 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:
[Code]...
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Jan 11, 2012
The 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]......
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Mar 25, 2011
I 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.
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Jun 19, 2012
The 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]
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Mar 4, 2009
I 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].....
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Jan 23, 2012
I need to catch log4net exceptions (its own exceptions not app exceptions logged by it). I wish there's a way of doing it this way: [code] I have this code implemented and there's no errors in compilation but i force log4net to have an error (pointing to a non existing database in the config file) and nothing is threw.I've tried the listener aproach: [code] and it's writing the errors to log4net.txt, the forced ones i mean.This last aproach has a couple of drawbacks: it won't append every error to the file, if the error is the same it doesn't write it, i can't get the listener to write every error to that file, only one (I don't know how to fully configure the trace listener, it might be that). Thus it won't append the date and hour to every line wich is a necesity for me. Finally i can't give structure to it (xml). Even if the listener work i need to use the try/catch aproach, since i'm using ExceptionHandling from Enterprise library to log the errors in my app.
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Feb 12, 2010
I am using VB.NET 2005 to create a Windows forms application. I have a procedure named SendMail that creates an instance of Outlook.Application, to send an email from my application. I found the code on this forum, I think.The procedure works fine, but I can't use error handling with it.I call the procedure from a button click event. I put the procedure call in a try/catch block, and the application won't build, with the following error.
Error 68 'Catch' cannot catch type 'Microsoft.Office.Interop.Outlook.Exception' because it is not 'System.Exception' or a class that inherits from 'System.Exception'. C:datadevdmtiQTSQTSv7_1_20100212wQTSQTSReportsCriteria
pt_frmReportViewer.vb 43 21 QTS
Here is the code:
Sub SendMail(ByVal sFile As String)
' Create an Outlook application.
Dim oApp As Outlook._Application
[code]....
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