How to check if a windows form is already open and close it if it is

Question

I have a form  fm  that is a simple info window that opens every 10 mins  fm Show       How I can make that every 10 mins it will check if the form  fm  is open and if it is open it closes it and open it again   Now the form fm is always created with form fm   new form    so when I try to check if the form is open it will always be false and open a new window even if there is one form before   I need to have a tool to give it a unique identity and then check if this form with unique identity is opened or not   I do not want to just update the data on the form  fm   because I have a complicated info with buttons   The form name is  UpdateWindow   Thanks

User · Answer

if    Form1 Application OpenForms  Form1    Visible    true        form is visible else       form is invisible   where Form1 is the name of your form

User · Answer

Form fc   Application OpenForms  UpdateWindow      if  fc    null      fc Close      fc Show

User · Answer

if  Application OpenForms  Form NAME      null       new Form NAME   Show        If the form instance is not open it will enter the IF loop

User · Answer

The below actually works very well   private void networkInformationToolStripMenuItem Click object sender  EventArgs e        var  open   false      FormCollection fc   Application OpenForms      foreach  Form frm in fc                if  frm Name     FormBrowseNetworkInformation                          open   true              frm Select                break                      if   open    false                var formBrowseNetworkInformation   new FormBrowseNetworkInformation            formBrowseNetworkInformation Show

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Form user rpt   Application OpenForms  frmUesr reports            if  user rpt    null                            Do Something here             Try This This is the short idea to check Form open or not open

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Suppose if we are calling a form from a menu click on MDI form  then we need to create the instance declaration of that form at top level like this   Form1 fm   null    Then we need to define the menu click event to call the Form1 as follows   private void form1ToolStripMenuItem Click object sender  EventArgs e        if  fm    null   fm Text                    fm   new Form1                          fm MdiParent   this          fm Dock   DockStyle Fill          fm Show              else if  CheckOpened fm Text                 fm WindowState   FormWindowState Normal          fm Dock   DockStyle Fill          fm Show            fm Focus                                                The CheckOpened defined to check the Form1 is already opened or not   private bool CheckOpened string name        FormCollection fc   Application OpenForms       foreach  Form frm in fc                if  frm Text    name                        return true                       return false      Hope this will solve the issues on creating multiple instance of a form also getting focus to the Form1 on menu click if it is already opened or minimized

User · Answer

this will word definitely  i use this function for myself as well     public static bool isFormOpen Form formm                 foreach  Form OpenForm in Application OpenForms                        if  OpenForm Name    formm Name                                return true                                   return false

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Hope This will work for u  System Windows Forms Form f1   System Windows Forms Application OpenForms  Order    if   Order f1   null      open Form   else     not open

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Try to wire below   private void frmMyForm Deactivate object sender  EventArgs e                   Raise your flag here          By wiring above event  it will tell you whenever the form is minimized  partially totally hided by another form

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private static Form IsFormAlreadyOpen Type formType          return Application OpenForms Cast lt Form gt    FirstOrDefault openForm   gt  openForm GetType      formType

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In addition  may be this will help    class Helper               public void disableMultiWindow Form MdiParent  string formName                        FormCollection fc   Application OpenForms              try                               foreach  Form form in Application OpenForms                                        if  form Name    formName                                                form BringToFront                            return                                                           Assembly thisAssembly   Assembly GetExecutingAssembly                    Type typeToCreate   thisAssembly GetTypes   Where t    t Name    formName  First                    Form myProgram    Form Activator CreateInstance typeToCreate                   myProgram MdiParent   MdiParent                  myProgram Show                              catch  Exception ex    MessageBox Show ex Message

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Form only once If your goal is to diallow multiple instaces of a form  consider following     public class MyForm   Form       private static MyForm alreadyOpened   null       public MyForm                    If the form already exists  and has not been closed         if  alreadyOpened    null  amp  amp   alreadyOpened IsDisposed                        alreadyOpened Focus                  Bring the old one to top             Shown     s  e    gt  this Close        and destroy the new one              return                                   Otherwise store this one as reference         alreadyOpened   this                Initialization         InitializeComponent

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Form1 fc   Application OpenForms  Form1       null    Form1   Application OpenForms  Form1      null  if  fc    null        fc Close        It will close the form1 you can open that form again if you want it using    Form1 frm   New Form1    frm show

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try this MDICHILD function   public void mdiChild Form mdiParent  Form mdiChild        foreach  Form frm in mdiParent MdiChildren                   check if name equals         if  frm Name    mdiChild Name                          close if found              frm Close                 return                       mdiChild MdiParent   mdiParent       mdiChild Show         mdiChild BringToFront

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maybe this helps   FormCollection fc   Application OpenForms   foreach  Form frm in fc      iterate through      if  frm Name     YourFormName                   bFormNameOpen   true             Some code in the foreach to detect the specific form and it could be done  Untested though   Found on http   bytes com topic c-sharp answers 591308-iterating-all-open-forms

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I ve tweaked an earlier post I made  This work flawlessly without having to iterate though all open forms           Form fc   Application OpenForms  FormBrowse            if  fc    null                        fc Select                      else                       var formBrowse   new FormBrowse                formBrowse Show

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This is what I used to close all open forms  except for the main form       private void CloseOpenForms                        Close all open forms - except for the main form    This is usually OpenForms 0                 Closing a form decrmements the OpenForms count            while  Application OpenForms Count  gt  1                              Application OpenForms Application OpenForms Count-1  Close

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I m not sure that I understand the statement  Hope this helps  If you want to operate with only one instance of this form you should prevent Form Dispose call on user close  In order to do this  you can handle child form s Closing event   private void ChildForm FormClosing object sender  FormClosingEventArgs e        this Hide        e Cancel   true      And then you don t need to create new instances of frm  Just call Show method on the instance   You can check Form Visible property to check if the form open at the moment   private ChildForm form   new ChildForm     private void ReopenChildForm         if form Visible                form Hide                Update form information     form Show        Actually  I still don t understand why don t you just update the data on the form

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try this   no need to iterate through the forms    if Application OpenForms   lt your form name gt       null         Your form is already open    else        Your form isn t open

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This worked form me   public void DetectOpenedForm         FormCollection AllForms   Application OpenForms      Boolean FormOpen   false      Form OpenedForm   new Form        foreach  Form form in AllForms                if  form Name     YourFormName                         OpenedForm   form              FormOpen   true                      if  FormOpen    true                OpenedForm Close

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I think my method is the simplest        Form2 form2   null      private void SwitchFormShowClose Click object sender  EventArgs e                  if form2    null               form2   new Form2                form2 Show                      else              form2 Close                form2   null

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In my app I had a mainmenu form that had buttons to navigate to an assortment of other forms  aka sub-forms    I wanted only one instance of each sub-form to be running at a time  Plus I wanted to ensure if a user attempted to launch a sub-form already in existence  that the sub-form would be forced to show  front amp center  if minimized or behind other app windows  Using the currently most upvoted answers  I refactored their answers into this   private void btnOpenSubForm Click object sender  EventArgs e                 Form fsf   Application OpenForms  formSubForm             if  fsf    null                        fsf WindowState   FormWindowState Normal              fsf Show                fsf TopMost   true                    else                       Form formSubForm   new FormSubForm                formSubForm Show                formSubForm TopMost   true

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This works if you want to Check if the Second Form is already Open and avoidt opening it again on buttong Click    int formcheck   0      private void button click                Form2Name myForm2   new Form2Name           if formcheck    0                     myForm2 Show      Open Form2 only if its not active and formcheck    0              Do Somethin            formcheck   1    Set it to 1 indicating that Form2 have been opened

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Try this  it will work      inside main class Form1 Fm1   new Form1    lt br gt     in button click if  Fm1 IsDisposed        Fm1   new Form      Fm1 Show    Fm1 BringToFront    Fm1 Activate

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Funny  I had to add to this thread   1  Add a global var on form show   and clear out the var on form close    2  On the parent form add a timer   Keep the child form open and update your data every 10 min   3  put timer on the child form to go update data on itself

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try this   bool IsOpen   false      foreach  Form f in Application OpenForms                if  f Text     Form2                         IsOpen   true              f Focus                break                       if  IsOpen    false                Form2 f2   new Form2            f2 MdiParent   this          f2 Show

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I know I am late    But for those who are curious    This is another way  if  Application OpenForms OfType lt UpdateWindow gt    Count      1      Application OpenForms OfType lt UpdateWindow gt    First   Close     UpdateWindow frm   new UpdateWindow   frm Show

[c#] How to check if a windows form is already open, and close it if it is?

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