Function - Pass Object Versus Reference Object In Parent?
Dec 1, 2011
I am working on a application that has quite a few functions involved and have been thinking of the following: If I have a function that has a few paramaters, is it more efficient to pass the objects to the function(Example 1) or reference the objects in the parent(Example 2)? Does it matter if the objects are large or not?
Example:
Class mainform
Public myGenericList As New List(Of String)
Public myDatarowArray() As DataRow
I call the function GetDataTable and when it gets to the return line, I get the error message: Object reference not set to an instance of an object.
Dim DB As New DBConn Dim gd As New DataAccess.GetData Dim DT As New DataTable
[Code].....
Updated. I'll see if I can update with the DataAccess.GetData code. I didn't originally put it in there because our shop use it all the time and have no issues with it.
I pass this class i created a variable by reference and i want that reference to be assigned to m_Text so that when i change m_Text it changes the TextValue variable i passed. Example:
Dim test2 as String = "ok" Dim test as New GeneTextBox(test2)
'then some one changes the text in the GeneTextBox and i want it to change the test2 string...
Public Class GeneTextBox Inherits Windows.Forms.TextBox Private m_Text As String Public Sub New(ByRef TextValue As String)
I'm trying to give a default value to the register property method. This required a function, but passed as an object(delegate?).[code]....
I want to call that registerproperty method, but I don't know how I can do that in VB.net. I just need to pass along a new Person object and I thought this was the way to go[code]....
How do you pass a control (say a textbox) to a function as a parameter in compiled assembly using CodeDom? I've tried passing through the args in the Invoke method but it doesn't work.[code]...
This should be a fairly common question, but I haven't found a straightforward answer anywhere.
If I instantiate an object within a function in VB.NET and return it, does it return it be reference or by value. IE - should I be worried about performance if I write something like this:
Public Function ret_obj_func() As big_object Dim ret_obj As New big_obj(<lots of stuff>) Return ret_obj End Function
If I call this function from somewhere else, will it instantiate the object in the ret_obj and then create a deep copy to pass back a copy to the caller, Or will it just pass back a reference?
when I was a comparitive novice to the novice I am right now, I used to think that these two things were syntactic sugar for each other, ie. that using one over the other was simply a personal preference. Over time, I'm come to find that these two are not the same thing, even in a default implementation (see this and this). To further confuse the matter, each can be overriden/overloaded seperately to have completely different meanings.
If I instantiate an object within a function in VB.NET and return it, does it return it be reference or by value. IE - should I be worried about performance if I write something like this:
Public Function ret_obj_func() As big_object Dim ret_obj As New big_obj(<lots of stuff>) Return ret_obj End Function
If I call this function from somewhere else, will it instantiate the object in the ret_obj and then create a deep copy to pass back a copy to the caller, Or will it just pass back a reference?
Private Sub SpellChkMenuItem_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles SpellChkMenuItem.Click Dim activeRichTextBox = TryCast(Me.ActiveControl, RichTextBox) 'clsFS.CheckSpelling(activeRichTextBox)[code]....
When I am in the rtb and click on spell check button it tells me the error "Object reference not set to an instance of an object." On this line
SpellChecker.Text = activeRichTextBox.Text
But it is suppose to be getting the focused rtb correct? So why is it not referenced
VB 2008 .NET 3.5 Suppose we have two classes, Order and OrderItem, that represent some type of online ordering system. OrderItem represents a single line item in an Order. One Order can contain multiple OrderItems, in the form of a List(of OrderItem).
Public Class Order Public Property MyOrderItems() as List(of OrderItem) End Property End Class
It makes sense that an OrderItem should not exist without an Order. In other words, an OrderItem class should not be able to be instantiated on its own, it should be dependent on an Order class to contain it and instantiate it. However, the OrderItem should be public in scope so that it's properties are accessible to other objects. So, the requirements for OrderItem are:
I have an ssis package that takes a flat file and dumps it to SQL. During that process, 150 columns need to have '-' and '.' removed from them. I have done this using a Script Transformation.
Public Overrides Sub Input0_ProcessInputRow(ByVal Row As Input0Buffer) Dim column As IDTSInputColumn90 Dim rowType As Type = Row.GetType()
[code]....
Edit I've discovered that this line is the problem
Dim strCol As String = columnValue.GetValue(Row, Nothing).ToString()
I am trying to start the process with the following parameters When I try to start it though I get an System.nullreferenceexception: Object reference not set to an instance of an object
Dim exepath As String = Application.StartupPath + "inffmpeg.exe" Dim sr As StreamReader Dim cmd As String = " -i """ + input + """ -ar 22050 -y """ + output + """" Dim ffmpegOutput As String
i am using VB.net 2003 and i am trying to get the number of rows of a dataset from form1 into form2 in order to use it for something else and i am getting the error"System.NullReferenceException occured...Additional information: object reference not set to an instance of an object"...my code is like this:in form1:Public x as integer= me.dataset.table.rows.count here it gives me the error
I am getting this error when I try to print my report. Here is my print code.
Private Sub PrintToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PrintToolStripMenuItem.Click Dim Print_Dialog As New PrintDialog
[code].....
Here is my error: System.NullReference Exception: Object reference not set to an instance of an object.
i am trying to allot a cell value to another cell value basing on some conditions & finally delete one column.my code is as fallows
Dim i, x As Integer i = 0 x = Me.DataGridView1.Rows.Count[code]....
error i am getting is : Object reference not set to an instance of an object.it is extremely surprising for me the same code has worked nice for me but why & how the same line of code is generating this error.
I tryed searching for an user in active directory using the code below but it gives me the error in the title of this post above:
AD = New DirectoryEntry("LDAP://OU=SchoolOUhere,OU=Staff,DC=garrard,DC=ketsds,DC=net", "", "", AuthenticationTypes.Secure) AD2 = New DirectoryEntry("LDAP://OU=_Groups,OU=Staff,DC=garrard,DC=ketsds,DC=net", "", "", AuthenticationTypes.Secure)
[Code]...
Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth. - "Sherlock holmes" "speak softly and carry a big stick" - theodore roosevelt. Fear leads to anger, anger leads to hate, hate leads to[URL]...
The issue is when I try to add a new item to the ArrayList with the following code, it gives me an error:
vb Private Sub btnLabelAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLabelAdd.Click Dim result As String = InputBox("New Filter Label:", "Label List")
[CODE]................
Object reference not set to an instance of an object.
I'm not really sure what I'm supposed to be doing with this. It's a new setting I just added and it's empty, so I'm not sure if that has anything to do with it or not. Anyone know what's going on and what needs to be done to get it to accept a value and not want to be "initialized"?
I have recently gotten my hands on a free, open-source IMAP connection API.So far, I have been successful in creating a connection to one of my accounts.Where I'm getting stuck is retrieving folders and/or emails from those folders.Does there happen to be anyone here that is familiar with this API, or even Gmail (particularly the folder structure for IMAP)?
If not, here is a link to the DLL that is listed on sourceforge and the company's website that created it (if you feel like testing):
Koolwired Sourceforge - Koolwired API
I have created a test account so feel free to use the code below without worrying about username/password issues; I'll just delete it when I'm done with it.Here is the code I have made so far for making a connection:
Dim gSession As New Koolwired.Imap.ImapConnect("imap.gmail.com", 993, True) Dim gAuthenticate As New Koolwired.Imap.ImapAuthenticate(gSession, "imap_test@serysoft.com", "imap_test") Try
[code]....
When I run that code, I get an error that states:System.NullReferenceException: Object reference not sent to an instance of an object. (The bold line in the above code).
Now, I'm not sure exactly what that means. Does that mean it tried to access the server and "INBOX" doesn't exist so it gets returned a NULL value? Or is it possibly the coding itself?Maybe the Gmail folder system is weird due to the fact they use labels (even though from what I have read online, the labels act as the folders in the IMAP system).
I was create Access database with Access 2003. I create VB project with Visual Studio 2005 Standard With connection wizzard I create coonect with this Access database, select all tablesI see this database inside Data sources and inside Server explorer Test connection is OK When I drag and drop table from Data sources, Wizzard don't create DataGridView, DataSourceBinding etc .. and I see popup window with mesage: Object reference not set to an instance of an object and then "game over"
The book "Beginning ASP .NET 4 in VB 2010" contains the following:NOTE: TaxableProduct inherits from Product.You can also cast in the reverse directionfor example, cast a Productreference to a TaxableProduct reference. The trick here is that this
Protected Sub CompetenciesButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CompetenciesButton.Click Dim con As String = WebConfigurationManager.ConnectionStrings("foo").ToString()
I'm trying to create a pivot table by opening an Excel file from my drive.But I'm receiving the error saying "Object reference not set to an instance of an object".[code]
I am completely new to ASP.NET and VB as well as C#. I am trying to add customers to a contact list out of a DB. Then the list can be referenced to call them up. But when I try to run it I get System.NullReferenceException: Object reference not set to an instance of an object. In line 19.
Here is my code:Page 1 is default page...it connects to the database and grabs the contact information and allows me to select the current contact and add them to a listbox on a separate page:
Imports System.Data Partial Class _Default Inherits System.Web.UI.Page
[code]....
The error occurs on line 19 (For Each customerEntry As DictionaryEntry In Customer) in the second set of code from the default2 class.
