Forms :: Throwing Exceptions From A DLL
Sep 13, 2011
I have a application in which dll of another project added,
In my dll's I have several exceptions defined, and when specific errors occur
I throw these exceptions with the assumption that the main application will catch and handle them if the DLL does not.
but when any specific error occurs in dll main application cant able to catch it and whole aplication get closed. i have added an snapshot which appears when any error appears in dll
how do i handle the exception raise in dll from main project
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Mar 5, 2010
Several of my overriden Equals methods have started throwing Invalid Cast Exceptions -
Unable to cast object of type 'System.DBNull' to type Common.ResolveUser'.
This occurs when binding List (of T) (where T is of type ResolveUser in this case) to a combo.
Equals Method:
Public Overrides Function Equals(ByVal obj As Object) As Boolean
Dim i As ResolveUser = CType(obj, ResolveUser)
If i.UniqueResolveID = UniqueResolveID Then Return True
[Code]......
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Nov 10, 2010
I never got into detailed error processing too much when I played in VBA/VB6 a lot. Mostly then, if you ran into a user error (such as some input of theirs failing a validation test of some kind), you popped a MsgBox() with some error information and the critical (or warning) icon, and safely aborted out of the code
In .NET, my reading basically points to exceptions as the end-all in error handling. It looks to me that if you know a spot of code where a user can screw up, you're supposed to catch it with either try...catch blocks (for things like data conversions), or standard if...the...else constructs for other things, and then throw a new exception if needed.
Isn't throwing an exception essentially a forced crash of a program in a sense (granted, you get the option of continuing)? Or are exceptions geared specifically for things like data conversion errors and other "things that shouldn't happen", and resume use of MsgBox() and friends for minor user screwups?
Consider the case of where you have a TextBox that is only supposed to accept numeric data (or heck, just a specific set of characters). Barring some other trick that lets you restrict that field (let's just assume it's freeform, programatically), it would seem a bit of a waste to throw new exceptions everytime they type in an invalid character, or even if the error checking doesn't happen until they press a submit button (like on a webpage). Popping a MsgBox() seems more sane in that case.
So what's the straight dope on exceptions and throwing new ones on user errors? How about if your program also exposes a programmatic framework? Bad usage of one of the programmatic functions definitely seems like new exception territory to me.
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Feb 22, 2011
The following code is throwing Exception. I don't get what mistake I am making in the code. i think it is of some security rights issue. If so, how can I give the security rights to any user or application to access this windows service programmatically?
Dim sc As New ServiceController
sc.ServiceName = "DataLoad"
If sc.Status = ServiceControllerStatus.Stopped Then
[code]....
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Sep 15, 2010
I'm running into some strange exceptions coming from a few workstations that are running one of our Windows Forms Applications. The application is written for .NET Framework 2.0 and coded in VB.NET. We've re-imaged the machines a couple of time but not matter what we do, the same problem occurs. We are not seeing this problem with any other machines besides these two. Below is the exception message and the Stack Trace. Can anyone provide any insight as to why this may be happening?
[Code]...
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Dec 26, 2009
I've just skipped around a few inbuilt VB classes' methods which throws exception. of all that i've came across, methods may throw multiple exceptions but ALL of them are exclusive, meaning there is no way 2 exceptions will ever occur simultaneously, yea and i was trying to make my class throw 2 exceptions simultaneously, hence this question, must all exceptions be exclusive?
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Mar 21, 2010
I have the following code:
[Code]...
I thought at first that because during testing GetFormsByStatus() returns 0 results maybe that was causing problems, but it doesn't make sense that Except() wouldn't work if the provided list had 0 items.
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Aug 23, 2009
I have the following code:
Public Shared Function GetAvailableManufacturers() As List(Of Manufacturer)
'first get all the live orders and extract their mfrs'
Dim sos As List(Of OrderForm) = GetFormsByStatus(StockStatus.Building)
Dim unavailableMfrs As New List(Of Manufacturer)
[code]....
My idea to get available manufacturers was to get a list of all the manufacturers in my open forms, then get a list of all manufacturers and exclude all the manufacturers in the first list, illustrated like so (pseudo):
List A: {1,2,3,4,5,6,7,8,9,10}
List B: {5,7,10}
Result: {1,2,3,4,6,8,9}
I have set up my Manufacturer class according to this article so that it can be compared, but I'm still getting this error:
Unable to cast object of type '<ExceptIterator>d__92'1[csCore.Manufacturer]' to type 'System.Collections.Generic.List'1[csCore.Manufacturer]'.
I thought at first that because during testing GetFormsByStatus() returns 0 results maybe that was causing problems, but it doesn't make sense that Except() wouldn't work if the provided list had 0 items.
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Feb 24, 2012
The following sub is throwing a"Object reference not set to an instance of an object."
exception.
For Each element As Song In modFiles.getSongs()
Dim col(2) As String
[code].....
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Feb 27, 2012
I have a question about how to properly deal with errors. I am working on a three tiered application. If an error is created on the data tier, I would like to pass the error to the business tier and process it there.What is the best method to accomplish this? I am using .net 2.0 and visual studio 2005.
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May 19, 2011
I'm throwing an exception that looks like this...
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Mar 5, 2010
I have an ASP.NET page with code-behind in VB.NET. On the ASPX page I have a Repeater with an asp:ImageButton inside the repeater and I want to catch the clicks on the button. As far as I read I have to use FindControl and then handle the copy of the original control:
[Code]...
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Apr 23, 2010
Why would my try-catch block still be throwing an error when it's handled?[code].......
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Dec 1, 2010
I am trying to use page methods to call a function and I am getting a "PageMethods is undefinded" error. I have used them before whilst using C# but not VB so I'm wondering if my syntax is wrong as all examples I can find are C#. I am also wondering if it's because my scriptmanager is on the master page?
I've read about this error everywhere but everything I have appears to be correct!
My code:
Part of Master Page
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true" EnablePageMethods="true" >
[Code]....
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Mar 4, 2012
Can someone please explain to me what this error means? I am new to VB programming and don't understand this. Error : Type 'var' is not defined
Here's my code
[Code]...
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Oct 25, 2011
I have the below bit of code that allows a user to see data in a DataGridView. They can click on a single row and open another form with the detail of the selected item. Once the user returns from that form I refresh the original screen with anything that might have been changed from the other screen (or by other users elsewhere in the network).
This works perfectly fine to select items, go look a the detail and change anything you like, then return and refresh the screen with the new updated information, with one notable exception. I get a NullExceptionError whenever the user has changed the default datagridview sort option on the first screens grid screen. Then selects and item and goes to the second screen and comes back to the first screen. And the really strange thing (to me) is that the first record on the return gets added fine, it is the second record it tries to add that is throwing the error.
Other notes: all variables have values (not nulls), the tableSelect is also valid and not equal to nothing.
If sqlConn.State = Data.ConnectionState.Closed Then sqlConn.Open()
Dim r As Data.SqlClient.SqlDataReader = sqlComm.ExecuteReader()
If r.HasRows = True Then
[Code]....
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Mar 22, 2011
My code block is below. As it turns out, rdrCurrentRate.GetString(12) is a null value, but the code block throws an error. "Data is Null. This method or property cannot be called on Null values."My intention is to write "if rdrCurrentRate.GetString(12) is NOT NULL, then sCurrentRateType = rdrCurrentRate.GetString(12)"
What am I missing here?
If Not String.IsNullOrEmpty(rdrCurrentRate.GetString(12)) Then
sCurrentRateType = rdrCurrentRate.GetString(12)
[code].....
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Feb 24, 2012
I am getting an exception when running the following code.
Public Function getSongs() As Song()
' Dim dir As New DirectoryInfo(Application.ExecutablePath)
Dim dir As New DirectoryInfo(directory)
[Code].....
I get an uncaught exception that says:
"Object reference not set to an instance of an object."
The song object has a:
Public Sub new(By Val filename as String)
... sub that sets a variable and retrieves file info (this code works)
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Sep 7, 2010
I cant see what is wrong with my SQL statement syntax [code]...
ERROR [42000] [MySQL][ODBC 5.1 Driver][mysqld-5.1.41]You have an error in your SQL syntax;check the manual that corresponds to your MySQL server version for the right syntax to use near 'Int,Agi,Money) VALUES('MyUsername','MyPassword',0,0,0,0)' at line 1
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Nov 23, 2009
I have a problem with running CLR profiler. It throws an exception: See the end of this message for details on invoking just-in-time (JIT) debugging instead of this dialog box.
[code]...
I started out with a console application but half way I switched to windows form in the application properties. Does that have something to do with it? I do this because I don't want to show the console. My application takes about 57 miliseconds to run. Maybe it's too fast for the clr profiler ?
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Jan 20, 2010
Imports Excel = Microsoft.Office.Interop.Excel
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
[code].....
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Nov 10, 2009
I am creating a simple mathematical game in VB.NET for kids!!the game checks for some simple calculations!!I am having the problem regarding the if else block in the codehere is my code
[code]...
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Oct 7, 2010
I'm passing in a sql command such as "EXEC StoredProc 0" into a a function called ExecMyCommand where StoredProc is a stored procedure taking a parameter of 1 or 0.It works fine with the following code.I had tried to judge success by looking at NumRowsAffected but soon realized that the -1 could represent a successful run even if -1 was the return value.So then I changed the code and return mLastRunOutcome = False if there is an error.So for testing I changed the name of the SP to like StoredProc2 in the database and ran the same command "EXEC StoredProc 0" and to my amazement, no errors were thrown in the code below..Of course ran the same command in Query Analyzer and it barked that there was no SP by that name.How do I know when a command ran successfully or not in code here? and Why didn't the ExecuteNonQuery throw an error when the command was not right??[code]
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Oct 7, 2011
I just noticed this, but I had a for loop where I incremented beyond the number of elements in an array. Normally this would thrown an exception.
This was in a form load event, and all that happened was the rest of the code in the event never executed. If I wasn't looking for what was supposed to happen next I never would have known there was a problem!
There was no try catch block there... but I would think it would still stop program execution with an error.
Can anyone explain this? Do I have some stupid skip error checked somewhere (if this exists, I'm going to be really annoyed)? In a button click event I put the exact same code and it threw the error... it seems to just be a problem with a form load event.
My IDE is VS2010 professional (vb)
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Aug 19, 2009
Is there a command that will stop the execution of my program?
I have a service that is processes an exchange account via telnet every 10 minutes. During one point of execution the application could possibly have a response from the telnet session when there are NO e-mails in the folder, which would look something like this[code]...
So is it possible for me to just stop my application at that point since there's no point in continuing if there are no e-mails in the account?
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Mar 30, 2011
I am having a weird problem. IIf is messing up when I am working with an array. Apparently it is checking my else statement even though it isn't activated. Here is some code that demonstrates the issue:[code]
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Jan 25, 2012
I am trying to get the type of a class by calling Type.GetType(), however it is throwing an null reference exception. I'm supplying the fully qualified name of the class as a string, I'm not sure what I am doing wrong. Here is what I am doing:Type.GetType("The.Name.Space.TheClassName")That is the fully qualified name of the class, it works fine for import statements.
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Apr 18, 2011
I am trying to read all selected items from a listbox in Visual Basic.
Dim x As Integer
Dim testValue As String
testValue = "20"
[code].....
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Jan 24, 2010
i did this Dim strUser As String = txtacno.Text cmd1 = New OleDbCommand("Select * from BookDetails Where AccountNo =@acno and MemberId=@memid", con)
[Code]...
the select query that i used in the above code,i have use and in it;so is this a valid sql statement?
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Aug 8, 2010
I'm familiar with Throw New Exception(), and how this causes an application to "break" with an error at the Throw line itself.But what I'm after is a way to throw the exception within a function, and for the application to break at the line which called the function - not at the Throw statement itself.Is there a way of doing this, but without having to wrap the function call within a Try-Catch?
For example:
1. Main code calls function "DoThis()"
2. DoThis() runs and throws an exception
3. Code breaks at "Call DoThis()"
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