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).
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.
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]....
OK, I'd like to know the difference between the following two blocks of code:
Block A
Try
Something
[code].....
Sometimes I do this and I've seen others doing it too:
VB:
Try
DontWannaCatchIt()
[code].....
Is there some special way to catch exceptions in finally block ?
View 2 RepliesI 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]...
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].....
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'.
View 4 Repliesi 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]....
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]...
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.
View 2 RepliesI 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?
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]
View 3 RepliesI 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.
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]
View 8 Repliesi 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 RepliesI 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]....
i have a problem with my code: [code] At the bold part, when i goto debug my program i get the error "Conversion from string "TrueFalse" to type 'Boolean' is not valid."
View 3 Repliesi'm trying to make a program in Visual Basic 2008 Express Edition that Opens and closes a process/application with an Error Handler.
View 4 RepliesWith Try/Catch is there a way to catch a MSSQL error by Msg ID? I want to catch a 208 when a table is not found and then create it. I found mockup code in C# but nothing VB.NET wise as to how to grab the Error ID.
View 1 RepliesI have the code below which I now need to figure out how to not only display but also email it all to my email, this way should any user encounter a error we get to see exactly what is it.
[Code]...
So I want to now if that possible for .NET languages to ignore error without using try catch construction ?
I can ignore warring with #nowarring 40 for example, can I ignore error ?
simply wanted to call system pause with this way
open System.Runtime.InteropServices
[<DllImport(@"msvcrt.dll")>]
extern void system(string str)
system "pause"
but got Error message
unbalanced stack. This is probably because the managed PInvoke signature does not match the unmanaged target signature. Make sure that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.
So I don't care, it works. But can I just ignore this error ? without doing weird stuff like that :
try (system "pause") catch |_->()
Ok , I solved my problem by adding CallingConvention=CallingConvention.Cdecl, but what the question was about skipping exceptions, so and I still don't know if I can do it.
So maybe I need to tell some real reason to not be down-voted hard - sometimes it's matters for program to live even with hard errors occupations, but even sometimes you don't need to catch them. You need just ignore them...
Why would my try-catch block still be throwing an error when it's handled?[code].......
View 8 Repliesi must receive that block of an error message from lblfeedback when it happens so i can sort out the problem before the phone rings. i have this block of code
[Code]....
Is there a way to catch a database exception and then redirect to an error page? I have a data access class that I use to make a sql connection and then functions that call it to execute my SQL commands. My problem is that if my database is not available I cannot catch that error. Here is the code I am using in my class[code]...
View 3 RepliesFirst I found that you can catch it and log it inside a catch, but this doesn't send an email. Then I found out about using the Error Signal class. That worked, however what wasn't apparent from reading, is that it treats the error like normal, so when I signal the error it goes to the custom error page still, I don't want that to happen. What I want to do is catch that error, log it, send the email, but stay on the page the error happened so I can provide special feedback. I do not want it go to the custom error page.
This is what I have and it redirects me to the custom error page.
Try
smtpClient.Send(mailMessage)
Catch smtpEx As SmtpException
errorSignal.FromCurrentContext().Raise(smtpEx)
Catch ex As Exception
[Code] .....
I m selecting the folder & playing all the files in the media player, of that folder. As u know folder contains all types of files including text,zip,image & so on.So I want that when URL that is assigned to Media Player is .txt,then i assign any default image from resources.I do not want to check extensions-Currently I m checking the extension of each file before paying but i dont want dat.
Public Class Form1
Public Ext_bmp As String = ".bmp"
Public Ext_jpg As String = ".jpg"
[code]......
I have written another windows application A. I then use another application B using process to run the application A. My main problem is to catch the error generated by application A so that application B can then perform some actions.
View 7 Replieshere is the code, i want to clear just the box with the error in it. if possible and leave the other numbers in put as they where.
Private Sub btnCalc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalc.Click
' the following declare the values that will be used
[Code]....
