Trying to close all opened forms in visual basic

Question

I want it so when my button is clicked, I exit my application. I tried a simple for loop:

Private Sub CloseAllToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles CloseAllToolStripMenuItem.Click
    For Each Form In My.Application.OpenForms
        Form.Close()
    Next
End Sub

But after closing all forms besides the form with this button on it, I get this error:

An unhandled exception of type 'System.InvalidOperationException' occurred in mscorlib.dll Additional information: Collection was modified; enumeration operation may not execute.

I believe this is because I close the form executing the code before the loop can go to the next form. If this is the case, how can I make it so my loop finishes once the last form is closed? Can I even do that?

Do you want to exit the application or you want close all forms except the current form? — Reza Aghaei, Jan 17 '16 at 23:47
If you close the main/statup form the app will likely end, is that what you want? — Ňɏssa Pøngjǣrdenlarp, Jan 17 '16 at 23:50
Is this what you need? `System.Windows.Forms.Application.Exit()` — Reza Aghaei, Jan 18 '16 at 00:01

Reza Aghaei · Accepted Answer · 2016-01-18T00:48:16.327

13

Close all but current form:

My.Application.OpenForms.Cast(Of Form)() _
              .Except({Me}) _
              .ToList() _
              .ForEach(Sub(form) form.Close())

Close application normally:

Application.Exit()

Force application to exit:

Environment.Exit(1)

edited Jan 18 '16 at 00:48

answered Jan 18 '16 at 00:13

Reza Aghaei

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Can you explain the reason behind `Environment.Exit(1)`? As my understanding that is used for console based applications... Also if you don't have the permission flag you will throw a security exception. – Trevor Jan 18 '16 at 00:26
@Codexer [`Environment.Exit`](https://msdn.microsoft.com/en-us/library/system.environment.exit(v=vs.110).aspx) Terminates this process and returns an exit code to the operating system. – Reza Aghaei Jan 18 '16 at 00:30
I know what it does but why doesn't Application.Exit suffice enough? – Trevor Jan 18 '16 at 00:31
2

@Codexer The difference is between close gently or force to exit (kill). For example, put a message box in closing event of some forms and ask about if you really want to close the form and set `e.Cancel=true` to see the difference. – Reza Aghaei Jan 18 '16 at 00:33
@Codexer You are welcome:) Hope you find the answer useful :) – Reza Aghaei Jan 18 '16 at 00:39

score 1 · Answer 2 · answered May 23 '17 at 22:20

1

This is simple, just add a validation:

        For Each Form In My.Application.OpenForms
            If Form.name <> Me.Name Then
                Form.Close()
            End If
        Next

answered May 23 '17 at 22:20

user8056176

19
1

Also make sure to set Shutdown Mode from :`When startup form closes` to `when last form closes` – Malcolm Salvador May 24 '17 at 00:38
In a foreach loop on a generic list you have modified the list (you have added or removed something). That can not be done. – Shadros Jul 22 '21 at 08:55

score 1 · Answer 3 · answered Nov 14 '20 at 17:37

what this does is close all form except "exceptthisform" or the mainform

     Dim formNames As New List(Of String)

        For Each currentForm As Form In Application.OpenForms

            If currentForm.Name <> "exceptthisform" Then

                formNames.Add(currentForm.Name)

            End If

        Next

        For Each currentFormName As String In formNames
            Application.OpenForms(currentFormName).Close()

        Next

Trying to close all opened forms in visual basic

3 Answers3

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