检查表单是否已打开 [英] Check if form is Opened

问题描述

我提出这个问题是为了获得更多知识.我怎么知道表单是否在我的应用程序中打开，为了不再打开它，我的意思是不要在运行时创建相同表单的实例

I give this question for more knowledge. How can I know if the form is Opened in my application or not, in order not to open it again I mean not to create an instance of the same form while it's running

   Dim frmCollection As New FormCollection()
    frmCollection = Application.OpenForms()
    If frmCollection.Item("Form2").IsHandleCreated Then
        MsgBox("Yes Opened")
    Else
        Dim f As New Form2()
        With f
            .Text = "form2"
            .Show()
        End With
    End If

如果我多次执行此代码，它将创建更多 Form2 形式的实例如何检查此表单是否尚未打开

if I executes this code many times it will create more instances of the form Form2 How can I check if this form is not already opened

推荐答案

你可以这样试试:

 Imports System.Linq ' need to add 


If Application.OpenForms().OfType(Of Form2).Any Then
  MessageBox.Show("Opened")
Else
  Dim f2 As New Form2
  f2.Text = "form2"
  f2.Show()
End If

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