VS 2008 Casting An Object?
Sep 30, 2009
I've got a project called Service.Inside the project, i've got 2 windows classes.ClassA is the main windows class which opens up when I run the program.On ClassA, I've got a button which, when I click it, opens up ClassB which is the other windows class. Inside the button's eventhandler (click), I've got a string which contains the name of ClassB's class ie "ClassB". I will probably get this from a table. Is it possible to initiate the object ClassB without using if statments to check what the type of object is. In the code below, i've managed to create a o of type object, but i need to new it with the ClassB
vb.net Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
[Code]...
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Mar 23, 2011
I have two custom objects.On of them inherits the other one, appends few more properties and methods, ovverides some other.When I try to cast the Parnet Object to Child I receive an error that it could`nt be done.
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May 31, 2010
Unable to cast object of type 'System.Windows.Forms.ToolStripButton' to type 'System.Windows.Forms.ToolStripMenuItem'.This is the error, when I click on the bookmark(When I add the bookmark, It's a non-clickable menu item; the next time i debug it, it becomes a clickable url(button)
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
...
Call minginimi()
End Sub
[code]....
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May 14, 2010
I have an object that inherits from an interface. I can create and return the following:
Dim o As IRequest
o = New Request
Return o
This works fine. Now I want to return a List(Of Requests), so I try the following:
Dim o As List(Of IRequest)
o = New List(Of Request)
Return o
The error below is being given on o = New List(Of Request)
System.Collections.Generic.List(Of MyObjects.Request)' cannot be converted to System.Collections.Generic.List(Of MyInterfaces.IRequest)'.Consider using 'System.Collections.Generic.IEnumerable(Of MyInterfaces.IRequest)'
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Feb 28, 2012
i have the following code which walks through an Excel file and this works fine note that the following line does work well (folder is being set earlier in the code)
[Code]...
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Feb 18, 2010
Okay, so I have a Generic IList of custom objects that I want to use as a datasource for a repeater.
Dim productRows As IList(Of MyCustomObject)()
'fill list with data
rptResults.DataSource = productRows
[code]......
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Jun 17, 2009
Here is a test program I wrote to explore a facet of object casting ...
Module Module1
Sub Main()
Dim class1 As MyBaseClass = New MyBaseClass()
Dim class2 As MyInheritedClass = New MyInheritedClass()
Dim class3 As MyBaseClass = Nothing
[Code] .....
The problem comes with the TryCast statement on class3. My intention is that class3 remains as a baseclass, but when the TryCast is applied, class3 morphs itself into an Inherited class which is not what I wanted. So is there a gap in my OOP/VB.NET knowledge and this action is legitimate or should class3 still be regarded as a base class?
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Jul 5, 2010
I've got a piece of code in a project (MyProject) that contains early bound object from a referenced assembly (We'll call it CommonAssembly):
Dim myObject As CommonAssembly.MyEarlyBoundType
now I have another assembly that is dynamically loaded because it is not present in all projects:
Dim myLateBoundObject As Object = AppDomain.CurrentDomain.CreateInstanceAndUnwrap("Utils", "Utils.MyLateBoundType")
MyLateBoundType derives from CommonAssembly.MyEarlyBoundType, and I want to cast myObject to myLateBoundObject and then programmatically invoke the additional
[Code].....
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Feb 5, 2009
I'm trying to write a (WPF) program with Option Strict on, but I have a problem.
I have a Canvas with a background image, and I want to use the coordinates of where the canvas was clicked to determine what should happen next. (Something like this)
Dim p As Point = e.GetPosition(DirectCast(sender, Canvas))
Dim imgColorMap As System.Drawing.Bitmap = My.Resources.ColorMap
Dim c As System.Drawing.Color = imgColorMap.GetPixel(p.X, p.Y)
This gives me the error: "Option Strict disallows implicit conversion of 'Double' to 'Integer'" for p.X and p.Y I have tried several things, like Math.Round but strangely enough that also returns a double.
How do I cast/round these Double values to Integer, so I can use them in my GetPixel method?
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Jun 26, 2010
I am a VB6 programmer learning VB.Net and am having trouble with the following concept.
[Code]...
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Mar 14, 2010
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"?
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Oct 23, 2009
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).
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Sep 15, 2010
What is the problem in below code.
d Public Sub filltextbox(ByVal dlist As String) Dim tb As TextBox = CType(Page.FindControl(dlist), TextBox) tb.Text = "hello" End Sub
Error : Object reference not set to an instance of an object.
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Apr 26, 2011
look after the error i'm having.
module1.vb
Imports System.Data.SqlClient
Module dbconn
[code]....
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Dec 5, 2010
I create one function to run any select query. and return the OdbcDataReader type.But some time if there is no data it through error : Object reference not set to an instance of an object I need to know how i can control if there is no data.
Public Function Select_From_AnyTable(ByVal sqls As String, ByVal ConStr As String) Dim conn As OdbcConnection conn = New OdbcConnection(ConStr) Dim cmd As OdbcCommand = conn.CreateCommand() conn.Open() cmd.CommandText = sqls Dim reader As OdbcDataReader = cmd.ExecuteReader While reader.Read() Return reader End While conn.Close() End Function Dim ei As OdbcDataReader = Select_From_AnyTable("SELECT loginname from usertable limit 1", conStr) msgbox(ei.item("loginname "))
If there is data it work well but if no record found it through the error.
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Aug 31, 2009
Is there a way to convert a DataGridViewRow object to a DataRow object?
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Jun 3, 2009
i have drawn on a e.graphics object and now want to transfer the drawn stuff onto a bitmap object how can i do this?
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Mar 21, 2010
Like every other program that you make when you code a button to open the next form it should open right. Well not in my case. I don't understand the problem that Visual Basics is not seeing my next form that I'm trying to open. When its in the Solution Explorer plain as day. Error below.An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.show is not set to a object. All its doing is opening the next form. Ive use this code over an over. Now its giving me this C.O.S. error.
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Nov 16, 2010
Basically all I am trying to do is to insert data entered in a text box(description) on the application form into database(sql2008) in vb.net. The vb code I wrote is below:
vb.net
Protected Sub Save_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Save.Click
Dim note As String = Description.Text
[code]....
However when I click on save button, I get following message:
System.NullReferenceException: Object reference not set to an instance of an object.
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Nov 30, 2010
What in this code might be causing this??This part of the code is Hilighted as causing the error.
My.Settings.Item(Holiday_" & i) = DirectCast(Me.Controls("ComboBox" & i.ToString), ComboBox).SelectedItem
Public Sub btn_Update_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
[code].....
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Mar 29, 2012
I am trying to clear a dataset in case it has some data already in so that I can add data to it to search a database, but when I run the program and get to the point that it tries to clear the dataset I get this error message "Object reference not set to an instance of an object", here is my
dtasetUser.Tables("tblUsers").Clear()Also I get an error "The 'Microsoft.ACE.OleDB.12.0' provider is not registered on the local machine" when trying to fill the same dataset, on searching I have found it is because I am trying to open a 2010 Access document in VB08, but I have no idea how to remedy this and any instructions I have seen make no sense to me, so I would like help with that too please.
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Feb 11, 2011
I am able to populate an object and output everything. How do I remove say the name2 object?
la.Remove(Logins("name2")) doesn't seem to work.
Private Sub btnListArray_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnListArray.Click
[code]....
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Nov 21, 2010
I'm trying to make a search textbox bring up certain records in a DataGrid. This is my code for that function:
Public Function Find(ByVal StrSearchString As String) As Boolean
DataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect
Dim intcount As Integer = 0
For Each Row As DataGridViewRow In DataGridView1.Rows
[code]....
The problem comes on this line:
If DataGridView1.Rows(intcount).Cells(0).Value.ToString = StrSearchString Then
I can't figure out what the unhandled exception is. Any ideas? I'm sure it's something very simple I'm overlooking.
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Mar 13, 2009
I have the following problem with MEF: Interface definition to be used by host:
Public Interface IExecuteDoSomething
Inherits IAddinSettings
Event DataReceived As EventHandler(Of DataReceivedEventArgs)
Function DoSomething() As Boolean
End Interface
[Code]...
Everything seems to work fine until the Button2_Click routine is executed, then an InvalidCastException is thrown with the info:Unable to cast object of type 'System.Collections.Generic.List1[SharedLibrary.IExecuteDoSomething]' to type 'System.Collections.Generic.List1[SharedLibrary.IAddinSettings]'.
How can i solve this problem, because the imported object implements both of the interfaces?
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Dec 9, 2009
The next code works fine in C#:
[Code]...
But this code crash with a OverflowException in VB.Net.
[Code]...
Both codes seems the same to me. What is the difference and how can I get the C# code converted to VB.Net?
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Aug 19, 2011
I have a object type variable (control .Tag) that I need to cast to a structured type, and change a member in. This is a contrived but representative example
[code]...
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Oct 16, 2009
get around this. I have a data base field that is a decimal data type and I want to display it in a text box with the following txtWeekdayRate = CType(RoomsDataRow!WeekdayRate, TextBox)I get the following error when I run my program.Unable to cast object of type 'System.Decimal' to type 'System.Windows.Forms.TextBox'.
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Mar 1, 2009
I am getting the followin error from my code. System.InvalidCastException was unhandled Message="Unable to cast object of type 'QADBASE.DMRDataLists' to type 'QADBASE.DMRData'." Source="QADBASE" I am getting the error in the code below on the createDMRIssue
[code]...
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Apr 20, 2010
Public Function CastToT(Of T)(ByVal GenericType(Of Object) data) As GenericType(Of T)Return DirectCast(data, GenericType(Of T))End Function
The above clearly does not work. Is there any way to perform this cast if I know that all objects inside data are in fact of Type T?
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Jan 12, 2011
I have an Entity class which Implements IWeightable:
Public Interface IWeightable
Property WeightState As WeightState
End Interface
I have a WeightCalculator class:
Public Class WeightsCalculator
Public Sub New(...)
..
End Sub
Why can I not do wc.Calculate(entities)? I receive:
Unable to cast object of type
'System.Collections.Generic.List1[mynameSpace.Entity]'
to type
'System.Collections.Generic.IList1[myNamespace.IWeightable]'.
If Entity implements IWeightable why is this not possible?
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