How to identify if a TForm is created yet and open?

Posted on 1997-11-17
Last Modified: 2010-04-04
I need a way for Form1 to know if Form2 is created and open.  Form1 is my Main (auto-created) form.  Form2 is created "on-the-fly" with a .Create method, and is then displayed with a .Show method.  Form2 does NOT have a caption, BTW.  How can I detect whether Form2 is created and open?
Question by:Kapusta
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions

Accepted Solution

Waldek earned 50 total points
ID: 1350787
if assigned(TForm2) then (Form2 is created)
Check ComponentState property for testing open and destroy state

Expert Comment

ID: 1350788
 It's improtant to realise that this will only check whether Form2 <> Nil. If you ever destroy Form2 then it will still return  True to the above call, unless you explicitly set Form2 := Nil, after the Free method.


Author Comment

ID: 1350789
Here is what I am trying to do...  do I need to add "Form2 := nil" as SteveB suggests?

procedure TForm1.Button1Click(Senter: TObject);
      Timer1.Enabled := True;
      Form2:= TForm2.Create(Application);

procedure TForm1.Timer1Timer(Sender: TObject);
      Timer1.Enabled := False;
      if Assigned(Form2) then begin
      MessageDlg('Time is up!',mtInformation, [mbOk], 0);

I want to force the Form2 to close SHOULD it be open when the timer on Form1 triggers.


Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
Monitoring a network: why having a policy is the best policy? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the enormous benefits of having a policy-based approach when monitoring medium and large networks. Software utilized in this v…

691 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question