Form1 Error

Hi Guys,

I am getting an error when i start debugging my program for a school assignment. When it starts to debug i get an error on the line 'Public Class Form1'. The following error message is:

Quote:

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InvalidOperationExeption was unhandled.
An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.

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I have spent a lot of time on this assignment and I can't believe this error has stopped me in my tracks because of something never touched!

PLEASE HELP!!!

Use the debugger and see what object has the value "nothing".

Sorry, I'm a real nube at this... please explain.

Thanks

Tim

Quote:

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Originally Posted by PCgeek

Sorry, I'm a real nube at this... please explain.

Thanks

Tim

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Can you show us the code that you have written? Does it compile properly or do you get any warning messages?

And yes debugging means you step through each line of code at runtime.

I have compiled and debugged this code before. It may be difficult to post all the code because it is spread over 5 forms and each has at least 3 pages. The only warnings i get are related to a streamreader object. When I debug after removing the stream reader object I still get the same error.

This is the beginning of form1

Code:

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Public Class Form1
    Inherits System.Windows.Forms.Form
    Public Shared f2 As New Form2
    Public Shared pin As Integer
    Public Shared username As String
    Friend WithEvents Depositbut As System.Windows.Forms.Button
    Friend WithEvents transferbut As System.Windows.Forms.Button
    Friend WithEvents Statebut As System.Windows.Forms.Button
    Friend WithEvents amountbox As System.Windows.Forms.TextBox
    Friend WithEvents Label5 As System.Windows.Forms.Label
    Friend WithEvents GroupBox1 As System.Windows.Forms.GroupBox
    Friend WithEvents okbut As System.Windows.Forms.Button
    Friend WithEvents Button6 As System.Windows.Forms.Button
    Public Shared loggedinuser As String
    Dim useraccount As String
...
...

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Did you touch any of the Designer Generated code? Also what about when you step through the code?

When does this error come up? Also put a break point on the line of code that is erroring out and then run the application.

I didn't touch the designer code. I made the UI all in the visual mode.

How do you step through the code?

This error comes up before the UI loads.

Putting in the break point didn't help, same result.

Tim

Oh so the UI doesn't load at all. Can you create a new project and add the existing Files in the new project and then run it. Probably that will help.

I coppied the entire code (class headings and all) into a new form and still got the same result.

Do i just copy the content that i wrote?

Thanks,

Tim

Don't copy anything. Create a new Project in VS and add each item that is present in the original project to this new project by using Add Existing Item from Project Menu. Then try again. Or if you can attach a zip file containing your project to this thread, we can also take a look at what is happening.

Here is a zip file of my assignment.

I really appreciate you help Shuja,

Thanks

Tim

Your code seems to be misplaced somewhere.. You are using .NET 2.0, right?

yes... That is the entire folder that i work out of... what is missing?

Change this line in your declarations at top of form

Code:

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    Dim changeamount As Integer = amountbox.Text

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to

Code:

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    Dim changeamount As Integer = 0

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Thanks Mate,

Will that be causing the

Code:

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public class form1

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line to be spitting out a error?

Tim

That didn't help I'm afraid... Thanks Any way.

Any more suggestions?

Thanks in Advance,

Tim

Looking at the code carefully, I have seen that you are assigning values to the variables outside of any code block. Which is not a good practice and is not supported by VB.

Do not assign anything to any variables in the declaration part of your code. Change the following two lines

Code:

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Dim changeamount As Integer = amountbox.Text

Dim keypad As Boolean = True

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To

Code:

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Dim changeamount As Integer

Dim keypad As Boolean

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This code is in Form1.

Make sure that you don't assign anything to the variables that are created outside of the functions/subs/properties.

I'm only in year 10 learning this. This assignment is due VERY Soon, i need help with the form1 error.

The previous suggestion didn't help

Thanks,

Tim

Quote:

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Originally Posted by PCgeek

I'm only in year 10 learning this. This assignment is due VERY Soon, i need help with the form1 error.

The previous suggestion didn't help

Thanks,

Tim

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Did you try the suggestions mentioned in my previous post?

aniskhan's and Shuja Ali's comments highlight and solve your problem.

When the program creates Form1, it goes into the Sub New, which is defined as:

Code:

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    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call
    End Sub

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Calling MyBase.New() makes it go through any variables that are declared with values.
Calling InitializeComponent() creates all the controls for the form.

The fact that they are called in that order means that MyBase.New() executes the line:

Code:

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Dim changeamount As Integer = amountbox.Text

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But amountbox is not yet created. InitializeComponent() is what creates it.

That's why you're getting the error.

So, if you wanted changeamount to start with the value in that textbox, you'd have to change:

Code:

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    Dim changeamount As Integer = amountbox.Text

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To:

Code:

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    Dim changeamount As Integer

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Then put "changeamount = amountbox.Text" in Sub New, after the InitializeComponent() call. But since that textbox's text property is defaulted to a blank string, that would still give you an error, so just don't set changeamount.

Only changing that one line of code allowed it to run for me.