Declaring A Object - Instance Of An Object To Be Created When A Form Loads Or Another Class Is Created
Oct 5, 2009
If you want a instance of an object to be created when a form loads or another class is created, you have two options:
Public class example
private IAmAObject As IAmAObject
public sub new()
[CODE]...
Or like this:
public class example
private IAmAObject as new IAmAObject
public sub new()
[CODE]...
I always use the first one. It's more type work but I think it's neater. How about you people and is there any real difference between the two?
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Aug 9, 2009
Not sure exactly what I need to do to make this work, so my description may be lacking at first.Essentially I am writing a program launcher that recreates itself each time on load. It pulls the data regarding the tabs and buttons from an SQLite database and builds itself dynamically at run time. I get my problem when I pass the tab name through to the function that creates the buttons. I need the name to pull the right set of buttons from the database and I then tried to use the name to place the buttons on the right tab when I create them, but the debugger calls it a null reference because it doesn't point correctly to the tabpage that I'm trying to make it point to (at least that is what I'm guessing). Any ideas on how to make this work right?
[Code]...
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Nov 11, 2010
I hope the question makes sense, anyways. I'm looking to know if in VB.NET, when we call an object's constructor, is there some kind of a reference that points back to the caller? I'm interested because of a corner case where I want the object being created to first be able to validate the existence of some data in the caller before it allows itself to be created. If this validation fails, I plan on throwing an exception. This corner case will never happen at runtime unless the object being created is used improperly by a programmer. The object being created is not inheriting the object I want it to validate, so I can't do anything with the MyBase qualifier.
It's bit of a "future-proofing" issue that I have a (bad) habit of doing. Not critical -- I can always leave stern comments behind as a last resort. Wanted to know if this was possible.
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Jun 2, 2011
I'm declaring a line at the top of my code window. Dim sTemp as String = textbox1.text
I tried commenting a few things related to the code but none of it makes it work.
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Aug 6, 2010
Here is the structure that I have:
Friend Class StandardFormatFile
Friend fileType As String
Friend numberOfSeries As Integer
[code].....
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Feb 8, 2012
creating single instance form in MDI Application. How to check whether form's instance created or not?
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Mar 30, 2011
I'm trying to develop a class in VB .NET in order to manage a language globalization stored in a database and editable by the user.What I need is to know what kind of class I need to declare in order to use it without declaring a new object. For example, the way My.Settings is used.
One of the goals is that in some project the developer imports the reference and after that access directly to a property. For example: My.CustomLanguage.GetWord("Hello") without declaring objects.
Is this possible? And if it's what is the best way to aproach it?
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Apr 13, 2012
I'm having this problem with my code and cannot seem to get past it although it was working fine before. The error is "An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object." The code is:
CODE:
I am trying to get information to be pulled out of a database and show in text boxes on another form (frmviewsdets). The error occurs when it gets to the line frmviewsdets.txtsnumber.Text = rdr("StudentNumber") and even when a breakpoint is applied there it just moves on to the next and so on.
I have tried to show frmviewsdets before I pull the data out of the database beut I get the same message.
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Mar 12, 2011
Under Visual Basic 2010, I am trying to define a specific instance of a static method that was created as a Java class. I have a vendor supplied dll added in as a reference.[code]...
But, I can't seem to define a specific instance of this method. Using "IntegrationMethod.getIntegrationMode()"always returns a value of zero.
There doesn't appear to be any way to "setIntegrationMode" to a specific value.
The documentatoin for this Class as provided by the vendor are shown below.
When I asked the vendor for assistance, their response was: "
Our javadocs for the IntegrationMethod class show that we provide three predefined instances of the IntegrationMethod class[code]...
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Apr 27, 2010
I am getting this error "Object reference not set to an instance of an object" and I dont know where/how to fix it and it does not tell me where the error in the code occurs, just a pop-up windows saying the error. Here is the code on the "start up" Windows form..
[Code]...
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Oct 11, 2010
I created an Access Object in vb.net:Dim acApp As Object = CreateObject("Access.Application.11")en I open Access I need to pass a parameter to it though "/cmd".I read that the only way to accomplish this is through a shell - that it is not possible directly using an Access object.
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Aug 12, 2011
I need to call this function saveBase from more than one place so i decided to send a number in variable x to know of what type to create the object named Model. however when it's within the if statemet i keep getting the error that model is not declared ![code]...
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Apr 12, 2011
I have a dll that create container object. How can dll inform a form that the container (me) has been created. Is it possible in new sub of that class?
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Jul 29, 2010
I need my program to open just one instance of each form, and if the person clicks again on the button that opens a form that is already showing, the form should only be brought to front (probably with the "bringtofront" method). How do I do this?I tried checking if the form "is nothing" before showing it, but if I close it and then try to open it again it doesn't work.
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Feb 22, 2012
I'm adding some functionality to an app that was made a few years ago and I need to raise an event when the tabcontrol is clicked. However it would seem because the control was created publicy I can't add a handler to it? I never ran across this before. I stripped the code down to the bare essentials. As you can see in the image, if I Dim the control within the sub I can add the handler. But any handler created for the publicly created control fails.
Is there another way to create the hander in this case?
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Dec 10, 2010
My
Public Class Form1
Dim x As Integer = 0
[Code]....
As you can see, i can retrieve the tag of the button (which is created at runtime) without any problems, i've made a temporary msgbox to show me the value of the tag, just for testing purposes. What i do have a problem with, is retrieving the tag of the individual web browsers, how should i do this?
Next issue, how would i code for my buttons to show the web browser with the same tag as the button that's just been clicked?
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Apr 3, 2010
I need to save a object that i programing to be drawed onto apictureboxPictureBox1.CreateGraphics().FillEllipse(Brushes.Blue, ci)how do i save the object as a image or the picturebox? And then be able to open it again?
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Nov 1, 2010
I have written some code to generate 10*10 textboxes during run-time.the problem is; I don't know how to access / change them after they are created. after some googling, I found this code to show the text of ie box42;
MessageBox.Show(Me.Controls.Item("box42").Text)
but it gives an error (nullreference exception was unhandled) hereby the code;
For i = 1 To 10
For j = 1 To 10
Dim tb As New TextBox
tb.Name = String.Format("box{0}{0}", i.ToString, j.ToString)
[code]....
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Aug 11, 2011
I want to make a lotto bulletin and i created the buttons in the program. I have assigned a handler to it and that is working also but how can i change the background of this button later on in the program ?
'/ teken 10 groupboxen
For i = 0 To 1
For y = 0 To 5
[Code]....
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Jun 6, 2011
I have a scanned document in my system. It's a tiff file. You will see below the code i have written. The problem is that i get an error message. The message is like this "A Graphics object cannot be created from an image that has an indexed pixel format." [Code]
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Nov 3, 2009
how would I create an event procedure for something not yet on a form?
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Apr 24, 2009
how do i change the property of a created object in the timer event? In other words i have a button that creates a panel for me, in a time event i want to change the created panels to a different backcolor, how would i do this?
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Sep 3, 2011
Say I have an object that I dynamically create. For example, say I create a button called "MyButton":
[Code]...
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Feb 3, 2012
Below is some code that I'm using to create objects with Visual Basic:
For indexCounter As Integer = 1 To TotalParticipants Step 1
participantClock = New Label
participantClock.Size = New Size(100, 20)
participantClock.Name = "participantClock" & indexCounter
[code]....
I'm creating a label, a button, Timer, and Stopwatch. (Though I have sinking feeling I don't need BOTH a timer and stopwatch since I'm counting time.)What I would like to do, is create the label and set that label's text to be the value from the stopwatch. The button that will be created will stop THAT stopwatch.
The problem that I'm having is that I cannot call the stopwatch by name since it wasn't created yet and VB throws a hissy fit at me for it. (After all it wasn't really declared.)So the question becomes, how do you call the most recently dynamically created control and assign events using that control. If it's not possible to do, I do not mind dumping the form and starting over creating 30 stopwatches instead (but I'd like to avoid that, if possible).
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Feb 17, 2011
I'm creating a textbox at runtime, which works fine, but now I need it to have a selection_change. How do I do that?
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Jun 8, 2009
I am trying to create a function that will return a pen(System.Drawing.Pen to be exact) that will have a random color and width. I thought that something like this should do the trick:
Public Function random_pen() As Pen
Dim clr As Color = Color.FromArgb(255, random_rgb_color_gen, random_rgb_color_gen, random_rgb_color_gen)
Dim pn As Pen = Pens.PeachPuff 'just a random color else i get a null exception...
pn.Color = clr ' the error is here
[Code].....
However when the code is run i get an Argument Exception with the error message:"System.ArgumentException was unhandled Message="Changes cannot be made to Pen because permissions are not valid.""
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Apr 30, 2009
WTF, here's my code...
Public Class Form1
Dim BIT01 As Integer = BIT_01.Text
Dim Value As Integer = TB_OutPut.Text
[code].....
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Nov 12, 2009
My problem is when i try to call Application.Run() in a application without a form i get "Object reference not set to an instance of an object." when i run it outside VS. but if ran in debug or release mode it works just fine. i may just be forgetting to setup application right, but ive done it before in this same manor and it worked fine.
Sub main() 'this runs first.
AddHandler Application.ApplicationExit, AddressOf ExitEventHandler
dbg_f("handle added")
[CODE]...
Commented out init_timer and init_ready, and now it causes the same error for the myName line. there seems to be something wrong with class Application. btw theres seems to be something wrong with the forum code formatting.
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Jul 10, 2010
I am somewhat new to object oriented programming and am attempting to flatten a Linq object hierarchy by using a shim class.how to initalize a derived class with property values from a base class?I have two objects, a base object with about 100 properties, and a derived object which inherits from the base object and adds a few additional properties beyond those of the base object. My simple constructor creates the derived object, but I am looking for a way to initialize the derived object properties with values from the base object.Right now I am using reflection to iterate over the properties individually and I suspect there may be a better way. The following example shows my shim class constructor for the derived class, and two properties:
newProperty1 - a new string property of the derived class
flattenedProperty2 - a new string property of the derived class, copied from a 2nd-level object of the base class
Code example:
Public Class derivedObj
Inherits baseObj
Private _newProperty1 As String[code].......
Is this the correct constructor approach to flatten the object hierarchy using a shim class? My second question relates to initialization of properties in the derived class. The constructor above creates the derived object, but what is the best way to initialize the derived object properties with values from the base object? The following code uses reflection to iterate over the properties individually, but I suspect there may be a better way.
Code example:
' property names are in the string array fieldNames
'baseObjQuery is an ienumerable of baseObj
'derivedObjList is a list of derivedObj[code].....
Is there a simple way to initialize values for the properties in the derived object based upon the values of the common properties in the base object?
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Aug 19, 2009
I have a class in which some of the fields are also classes.
I can put values in the "normal" properties, but in the others when o try to assign values it gives the: "Object reference not set to an instance of an object"
But the code compiles fine.
dados_Defenicao = New ServiceReference1.draftClaimEntryDefinition
dados_Defenicao.arCode = "123"
dados_Defenicao.claimMarket.warrantyType = "w" - Here it gives the error
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