Application crashing when I close - Xtreme Visual Basic Talk

05-18-2006, 05:04 PM

Moohasha

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Location: Texas

Posts: 165

Application crashing when I close

I have a really annoying problem that the application SOMETIMES (not always) crashes when I close it. Here is my New() Sub for my main form:

Code:

Public Sub New()
    MyBase.New()
    MyBase.Size = New Size(600, 600)
    Me.Show()

    bRunning = InitD3D()

    Do While bRunning
        Render()
        Application.DoEvents()
    Loop

    CleanUp()
    End

End Sub

' Cleanup active DirectX objects
Public Sub CleanUp()
    If Not Nothing Is Sphere Then Sphere = Nothing
    If Not Nothing Is graphicsFont Then graphicsFont = Nothing
    If Not Nothing Is Camera Then Camera = Nothing
    If Not Nothing Is device Then device = Nothing
End Sub

bRunning is set to False if the Esc key is pressed. I'll step through it in the Debuger and it will exit the game loop, go through CleanUp(), get to End, and crash. I've tried different things, such as commenting out the call to CleanUp() which made it only crash sometimes, and commenting out the End so that it would just finish the Sub. When I did the latter, I added a MyBase.Close call whenever Esc was hit so that it would close. That caused it to crash when the Sub ended. The error messages are as follows:
If I try to end it with the End command, I get:

Code:

An unhandled exception of type 'System.NullReferenceException' occurred in microsoft.directx.direct3dx.dll

Additional information: Object reference not set to an instance of an object.

If I remove the End and let it kill itself, I get:

Code:

An unhandled exception of type 'System.ObjectDisposedException' occurred in system.windows.forms.dll

Additional information: Cannot access a disposed object named "Form1".

Any ideas what the problem is?

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05-21-2006, 06:12 AM

Iceplug

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Ending the program when you create an object is not very wise. You should have a subroutine (Main) create the object and then run some initialization routine. When your routine is finished running, the routine should end and the Sub Main should close your class.

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05-21-2006, 09:12 PM

Moohasha

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Isn't that what's happening when I comment out the End command? The New() sub is pretty much like Main() for a form, only it doesn't close after New() finishes (which is why I threw the End in there)

05-21-2006, 09:20 PM

Rockoon

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Does .NET really support this sort of stuff inside a constructor?

While I am not an OO expert, it seems to me that heavy work inside a constructor used to be frowned upon in a major way.

05-22-2006, 04:03 PM

Moohasha

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Location: Texas

Posts: 165

You may be right. I must have modified something in my original copy of the tutorials and ended up using my constructor as my Main().

I'll try fixing that. Thanx.

05-22-2006, 04:08 PM

Iceplug

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Definitely. I have not seen any good reason to be destroying any objects inside of a constructor. Especially if it is the constructor to your startup form...

If you startup with a startup form, you have an invisible set of calls that occur after the form is constructed... most notably, the form is shown (making a form appear is more than setting it to a new form). If you close it after it is constructed, the next call to show the form (that you won't see) will fail.