Sub To Handle Multiple KeyPressEventArgs (null Reference)?
Apr 22, 2011
I am using KeyPressEventArgs to restrict several text boxes to numeric entries only. Rather than repeat the code, I thought I would make a "RestrictToNumeric" subroutine and call it from each "KeyPress" event. Like So:
Private Sub txt1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txt1.KeyPress
RestrictToNumeric()
End Sub
[code].....
The problem I am encountering is that the variable 'e' is used before it has been assigned a value, causing a null reference at runtime.
So I tried to add Dim e As System.Windows.Forms.KeyPressEventArgs As?to the RestrictToNumeric sub.I cannot figure out what I need to "Dim" it as...
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Jul 16, 2009
I have a button 'start quiz' which uses the dataset to fill the quiz form - ready for the user to start answering the questions.However, I am getting a 'null reference' at the point where the 'navigate records' on the quiz form is called. Have looked up that it means I have a variable that is null. But I have declared all the variables etc. Not sure what I'm doing wrong. I am very new to programming and I have spent quite a bit of time on this already.This is the code for the student user login:
Private Sub btnLoginStudent_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoginStudent.Click
FrmQuiz.Show()
[code].....
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Dec 15, 2011
I have a fairly simple piece of code:
Private _PurchaseDelivery as PurchaseDelivery
Protected Overrides Sub InsertItem(ByVal index As Integer, ByVal item As PurchaseDeliveryItem)
[Code]....
Which is inside a class which overrides a custom list base. The code is occassionaly throwing an unhandled exception, System.NullReferenceException, on this line when used in production:
If _PurchaseDelivery IsNot Nothing AndAlso _PurchaseDelivery.DefaultSKUBinID.HasValue Then
DeafultSKUBinID is declared as an Integer? (Nullable Int) in the PurchaseDelivery class. I cannot see what might be causing this error, why would this be returning an error?
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Jan 19, 2009
I read stuff from a SQL DB (database) using a data set. Some of the columns in the DB may contain NULL. I want to go through the table in the dataset and print, or use in some other way, the data. But when I try to use a certain data that corresponds to a NULL in the DB my program crashes.How can I detect - in the dataset - that it has no value and that I shouldn't try to use it?
Private Sub Get�rendenLista(ByVal e As System.EventArgs)
'----------------------------------------------------------------------
' This function fetches a list of �rende from the table �rende
'----------------------------------------------------------------------
Dim cno As New SqlConnection
[code]....
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May 24, 2011
I have some MS SQL field with NULL value. when i am trying to use below in VB.NET code no result comming...
1- dim sqlq as string = "Select * from table where name3 = null and address3 = null"
2- dim sqlq as string = "Select * from table where name3 = '' and address3 = '' "
But if same query # 1 i run direct SQL Query browser it works well.
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May 24, 2009
I've got a subquery that returns the most recent value from a child table. In some cases the subquery returns nothing. The query below fails at runtime because the inferred type of MemberPrice is decimal and is not nullable. [code]...
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Apr 26, 2011
What are NULL values? Sometimes when I try to assign a query to variable, I get error saying:
Type-Cast-Error. txtMiddleName.Text = Reader.GetString(2)
How can I put it that if the value of the Middle is nothing then txtMiddleName.Text = "". Working on VS 2010 (VB.net) EDIT 1: This is the error Message I get (Line 364 is the above mentioned code)
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Jul 17, 2011
On a ASP.net form, I need to add a textbox to update a date field in MS SQL server via stored procedure. I want to verify user input cant figure out the correct syntax to do so (please see below)
If d.Text <> "" Then
cmd.Parameters.Add("@date", SqlDbType.DateTime)
cmd.Parameters("@date").Value = Date.Parse(d.Text)
[Code].....
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Mar 30, 2011
I need to round and print a price like below, but this does not handle null values.How can I handle null values on one line of code? DBRSet is an SQLDataReader and the price is money
<%= Math.Round(DBRSet("price"))%>
I have about 200 .aspx pages of this so I could also use some tips on how to change these in an easy way? Can I do a search and replace with a reg-exp or something like that?
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Jun 11, 2009
In a WinForms app (VS2008 / .Net Framework 3.5) I bind data from SQL Server to controls. If there's a null value e.g. an employee has no middle name (allowed by business rules), when I browse that record at runtime an exception is thrown. So I code: If Not (row("middle_name") Is DbNull.Value then txtMiddleName.DataBindings.Add(New Binding("Text", row, "middle_name)). Say someone adds a middle name to this record, because the control had no databindings the dataset.HasChanges property is false and update stored proc doesn't run. I guess I could handle this like this: If txtMiddleName.Databindings.Count = 0 AndAlso txtMiddleName.Text <> "" Then row("middle_name") = txtMiddleName.Text. I guess I would have to do something similar to handle a value changing from not null to null.
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Feb 16, 2011
I have run into this problem a few times and have never come up with a good answer. I figure others must have dealt with this already.I have a datareader returned from the database and I want to use the values therein however values may or may not contain NULL. I would like to have a unction that takes in the value from the datareader and returns the value if it is not NULL and blank space if it is NULL.The problem I have is that the data-type of the variable I am testing is variable. It can be a String, and Integer or a DateTime. Can anyone suggest a simple way to test the value and then return the original value (as same data-type if possible) or something else if it is NULL
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Apr 18, 2011
I am reading dates from a table in a database to display in a DataGridView column that is formatted as a date. The problem is that when the value is null in the database my program errors out because it cant convert the value to a date. How do you guys handle this? *Edit: If I set the value of my date variable to "Nothing" it displays as "1/1/0001" in my DataGridView, and I would like the cell to be empty for the null dates.
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Aug 21, 2011
I'm converting a pretty large chunk of code into a Class so that it can be re-used more easily, but am having a problem with one of the Methods. I have a method that uses the following line:'GET HANDLE OF ANY POPUP WINDOW ASSOCIATED WITH MAIN FORM [code]The "Me.Handle" part won't work, but I don't know what to replace it with so that it knows to use the handle of the main application's form that is using the Class.Do I need to get all Process that match my application's and store the Process' handle?
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Jun 2, 2010
This is related to my previous question but it is a different problem.I have two classes: Server and Database.
[Code]...
The problem is in the LoadTables in the Server class. When it hits Databases.Add(db) it gives me a NullReference error (Object reference not set). I don't understand how it is getting that, all the objects are set.
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Jun 24, 2010
I have some code which gets child items for a menu via the GetChildren function which takes a list of menuData: Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
If menuData.Children IsNot Nothing Then
menuData.Children.AddRange(GetChildren(menuData))
End If
Next
If I check if menudata.children isnot nothing, it always is nothing because the GetChildren function is yet to run (providing the child items, which do exist). If I remove this check and just have this code:
Dim builtMenu As New List(Of MenuData)(_rawData.FindAll(Function(item) item.GroupingID = 0))
For Each menuData As MenuData In builtMenu
menuData.Children.AddRange(GetChildren(menuData))
Next
Then I am presented with a Object reference not set to an instance of an object error on menuData.Children.AddRange(GetChildren(menuData))
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Jan 8, 2011
I have been trying to use sockets in VB.NET and once I cannot understand how to avoid a null reference. [code] I have tried introducing sock as 'New Socket', but this gives me 'Overload resolution failed because no accessible New can accept this number of arguments'.I also cannot simply add '= Nothing' onto the end of my declaration since this still gives a null reference.
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Jan 29, 2011
I'm practicing on this one, and I know it would be better to just use a string variable instead of a class. I have another working program using a string variable, but on this one I wanted to make it use an array of class objects.
I keep getting null reference exceptions at the line where the object is assigned the textbox text.[code...]
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Dec 16, 2010
How do I check for a null object in a subroutine handle?
Private Sub Form1_KeyDown( _
ByVal sender As Object, _
ByVal e As System.Windows.Forms.KeyEventArgs) _
[code]......
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Mar 21, 2011
I have a null reference warning. Dummy code as follows:
Dim poo As IEnumPooTypes
Toilet.GetPooInBowl(poo)
The variable 'Poo' says it may result in an object reference not set error but I cannot use the 'New' keyword with an instance. How do I make the warning go away?
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Jun 27, 2012
visual basic application prompting me a message "Object reference not set to an instance of an object". i have 2 project in one solution. One is developed in c# and other is in vb. i am calling a method of c# project in vb project. the vb code is:[code]when i debug vb project individually it works properly and when i call vb application from c# application, it prompting error. is i missed out any .net framework reference? [code]
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Jan 4, 2010
Im trying to write code that will insert 'records' into an xml file, but everytime i click the button to make the changes to the XML file, it throws a null reference exception, ive gone through this code must be 100 times and cannot find what needs to be declared as 'new' as i know nodes can't be 'new' and the doc is 'new'
Imports System.Xml
Public Class frmuseradmin
[code]......
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Mar 1, 2011
im using try catch to handle this error uponm deletion of record that is foreign key to other table but it seems that my try catch is not working. im using asp.net (VB). can anyone help me???' i want to display an error message in my page.
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Jul 26, 2011
My site has been running fine for sometime now until recently I see in the event viewer a null reference exception in the DNN core:
DotNetNuke.Common.Globals.GetStatus() in
F:BuildsMaintenanceWorkingDirectoryLibraryCommonGlobals.vb:line
1125 at DotNetNuke.Common.Initialize.InitializeApp(HttpApplication
app) in
[code]....
the line 1125 is:
_Status = UpgradeStatus.None
Which is a property of the Globals class and an Enum Also when this happens it doesnt just do it once then sort its self it does it roughly every minute for an hour or so.I made sure all dataprovider.instances are either in a using or a try catch finally or self closing(if the reader is not used)?
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Mar 7, 2011
I have the following code, which is meant to loop through a list of CheckBoxes and if checked if gets the text contained in the linked textbox through the tag of the Checkbox, i have used it before and it worked fine but this time i am getting the following error:
Null Reference Exception was unhandled
Dim DisCheckBox As CheckBox() = {chk0_6, chk6_12, chk12_18, chk18_24, chk2_3, chk3_4, chk4_5, chkXSB, chkSB, chkMB, chkLB, chkXLB, chkS, chkM, chkL, chkXL, chkXXL, chkXXXL, chkXXXXL, chkW8, chkW10, chkW12, chkW14, chkW16, chkW18, chkW20}
For Each Chk In DisCheckBox
[code]....
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Jun 13, 2012
I know I'm being an idiot here and I just can't work it out. But i'm trying to take some data back from a vb.net database. It's falling over with a Object reference not set to an instance of an object error. And before the code runs it's saying the variable is being used before it's set, but I can't see how. Code:
Private taNotifications As dsDataTableAdapters.NotificationsTableAdapter = New dsDataTableAdapters.NotificationsTableAdapter
Dim notification As dsData.NotificationsDataTable = taNotifications.GetDataByClientID(userrow.UserID)
If notification.Rows.Count > 0 Then
Dim notificationrow As dsData.NotificationsRow
Dim forwardURL As String = notificationrow.ForwardLocation
End If
It falls over on the Dim forwardURL As String = notificationrow.ForwardLocation
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Feb 24, 2010
P/Invoke on x64 null reference exceptions, I get null reference exceptions when I try to compile for x64 in .NET code that makes use of platform invocation services to call unmanaged code in dlls. Am I missing something obvious here?
[Code]
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Jul 19, 2009
I keep getting a null reference exception w/this program, and its on the line that declares the array. I've looked it over and over and I just don't see why... Can you let me know if you see anything obvious? I'm also getting an "index out of range" exception, but it looks right to me...I declared everything with an 11 for 12 months, 0 to 11 for the intcount.
[Code]...
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Nov 21, 2011
I'm having this exception while trying to get the value of a cell from a table.[code]...
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Oct 23, 2009
If Not obj is Nothing and obj.IsActive Then ' null reference exception??constructions like this in C# works, because obj.IsActive is not checked if the first condition is false...
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Apr 4, 2011
i have this sql transaction i am using to make sales.But when ever i run the code it give me this null reference exception.I do not really know what is wrong.
[Code]...
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