How do I unload all open forms in VB.NET?

Question

In the middle of converting VB6 code to VB.NET, I need to replace the following code that intends to close all open forms remaining in the application.

'close all sub forms
For i = My.Application.OpenForms.Count - 1 To 1 Step -1
    'UPGRADE_ISSUE: Unload Forms() was not upgraded. Click for more: 'ms-help://MS.VSCC.v90/dv_commoner/local/redirect.htm?keyword="875EBAD7-D704-4539-9969-BC7DBDAA62A2"'
    Unload(My.Application.OpenForms(i))
Next i

I've replaced the Unload function with Close (as indicated by TFM), but the compiler complains that OpenForms is not a member of My.Application.

Where can I access the open forms?

Solution 1

The OpenForms property returns a FormCollection. You can iterate through the collection to process all forms.

For each f as Form in My.Application.OpenForms
 f.Close()
Next

Solution 2

I uncovered this solution,

'close all sub forms
For i = System.Windows.Forms.Application.OpenForms.Count - 1 To 1 Step -1
    Dim form As Form = System.Windows.Forms.Application.OpenForms(i)
    form.Close()
Next i

...which looks alright (if not verbose), and I'll be able to test it just as soon as I can compile everything else..

Solution 3

Application.Exit will pretty much do the same.

AS I suppose you want to close the application anyway if all forms are closed.

Solution 4

The My.Application.OpenForms requires the VB.Net application to use the Application Framework (see Project Properties, Application, Enable Application Framework).

If you don't user the Application Framework, you can instead use the Application.OpenForms (from System.Windows.Forms namespace).

View more solutions

Comments

[Franci Penov]

pulling out the power plug will achieve the desired result as well. nevermind the few side effects... :-)))

[brasskazoo]

Its strange, I saw many people saying that this worked for them in VS 2005. My compiler refuses to acknowledge OpenForms (VS 2008)... Could it have been changed between the two versions??

[MarkJ]

The Form.Closed and Form.Closing events are not raised when the Application.Exit method is called to exit your application. If you have validation code in either of these events that must be executed, you should call the Form.Close method for each open form individually before calling Exit method.

[MarkJ]

It's in the VS 2008 documentation. msdn.microsoft.com/en-us/library/eh13dca9.aspx

[MarkJ]

Just tried it in VB2008 EXpress Edition. It works for me - does exactly what it says on the tin

[Cerebrus]

This is another way of applying for-each (with a slight performance difference for large number of iterations).

[brasskazoo]

The error is: 'OpenForms' is not a member of 'i_hi002.My.MyApplication'.

[Lucas Jones]

You can just use Application.OpenForms, as usually you have 'Imports System.Windows.Forms' anyway.

[brasskazoo]

Ahh... Thats what I was missing, the import!

[brasskazoo]

So All I was missing (thanks to person-b's comment) was the import - 'Imports System.Windows.Forms'!

[Cody C]

Also, if you want to throw the user back to a login screen if they might do something like hit logout you might want to unload all of the forms but not exit the application.

[Cody C]

I get a collection modified exception sometimes when doing this.

[Carl Onager]

This worked for me in VS2010 when Imports System.Windows.Forms didn't

[yu_ominae]

I converted the same code as the OP today and got a collection modified exception. In that case the old iterating through the collection backwards method works fine.

[AjV Jsy]

Thanks, that works better for me than the For each approach which gave me an error as the .close modified the collection it was iterating over.

[Guru Josh]

Ditto the comment of @AjV Jsy for me. I am using Visual Studio 2013.