VB.NET how to check if a form with a specific text is opened

Question

I have a form called Chatbox that i use for each contact that is clicked.

I do this with following code:

    Dim ChatBoxWindow As New Chatbox
    labelhandlename = DirectCast(sender, Label).Name
    ChatBoxWindow.Name = labelhandlename
    Chat_WindowList.Add(ChatBoxWindow)
    ChatBoxWindow.Show()

What i want to do is check ---

    Sub Chatbox(sender As System.Object, e As System.EventArgs)

    labelhandlename = DirectCast(sender, Label).Name
    Dim thisOne = Chat_WindowList.FirstOrDefault(Function(x) x.Name = labelhandlename)

    If Chatbox.name = labelhandlename Then

        thisOne.Focus()

    Else

        Dim ChatBoxWindow As New Chatbox
        ChatBoxWindow.Name = labelhandlename
        Chat_WindowList.Add(ChatBoxWindow)
        ChatBoxWindow.Show()

    End If

End Sub

Whats the best way to do this? (note: chatbox.name doesn't work)

Just don't lose your reference to the instance. Add it to, say, a List(Of ChatBoxWindow) so you can find it back later. Remove it from the list with an event handler for its FormClosed event. — Hans Passant, Mar 08 '16 at 14:42
It looks like you already have a list of them, so to find one should be simple: `Dim thisOne = Chat_WindowList.FirstOrDefault( function (x) x.Name="something")` or thereabouts — Ňɏssa Pøngjǣrdenlarp, Mar 08 '16 at 14:51
@visualvincent edited the code above but my sub gives me an error on chatbox.name — Thomas Dutoit, Mar 08 '16 at 15:53
What's the error??? EDIT: Aren't you supposed to get rid of the `If`-statement? The `thisOne` variable already holds the ChatBoxWindow you're looking for. — Visual Vincent, Mar 08 '16 at 15:55
perfect ;) thank you very much. maybe you can help me with another issue http://stackoverflow.com/q/35841444/5601492 — Thomas Dutoit, Mar 08 '16 at 16:09
@Visualvincent Maybe a little question. when i close a chat window, how can i delete that one from that list? — Thomas Dutoit, Mar 08 '16 at 16:15
What list?? I don't see any list in your code. **EDIT:** Oh wait... — Visual Vincent, Mar 08 '16 at 16:25

score 1 · Answer 1 · edited May 23 '17 at 12:31

1

You can try:

For Each myForm As Form In Application.OpenForms
    If myForm.Name = "something" Then
        ' Do something.
    Else
        ' Do something else.
    End If
Next

Application.OpenForms gets a collection of open forms owned by the application.

But make sure to take a look at this question and answer, as Plutonix suggests.

edited May 23 '17 at 12:31

Community

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1

answered Mar 08 '16 at 14:42

Stijn

1,970
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When i do this i get the following error: Collection was modified; enumeration operation may not execute. – Thomas Dutoit Mar 08 '16 at 16:01

score 0 · Answer 2 · answered Mar 08 '16 at 16:10

0

Sub Chatbox(sender As System.Object, e As System.EventArgs)

    labelhandlename = DirectCast(sender, Label).Name
    Dim thisOne = Chat_WindowList.FirstOrDefault(Function(x) x.Name = labelhandlename)

    If thisOne IsNot Nothing Then

        thisOne.Focus()

    Else

        Dim ChatBoxWindow As New Chatbox
        ChatBoxWindow.Name = labelhandlename
        Chat_WindowList.Add(ChatBoxWindow)
        ChatBoxWindow.Show()

    End If

End Sub

thanks to @VisualVincent AND @Plutonix

answered Mar 08 '16 at 16:10

Thomas Dutoit

129
1
12

Okay, removing the form when closing. Do you target .NET 4.0 or higher? If so you could do like this: `AddHandler ChatBoxWindow.FormClosed, Sub() Chat_WindowList.Remove(ChatBoxWindow)`. – Visual Vincent Mar 08 '16 at 16:29
I did this @visualvincent and does the same :): `Sub Chatbox_Closing(sender As Object, e As CancelEventArgs) Handles Me.Closing Dim thisOne = Chatsys.Chat_WindowList.FirstOrDefault(Function(x) x.Name = ChatRxUsername) Chatsys.Chat_WindowList.Remove(thisOne) End Sub` – Thomas Dutoit Mar 08 '16 at 16:41
Skip the variables and stuff in the `Closing` sub. Do it in one line: `Chatsys.Chat_WindowList.Remove(DirectCast(sender, ChatBox))` – Visual Vincent Mar 08 '16 at 16:56

VB.NET how to check if a form with a specific text is opened

2 Answers2