Argthtjtr

I have been looking for some time on ways to open a second form from another already shown form.

This is some piece of code that works:

frmSecond second = new frmSecond();

this.Hide();

second.ShowDialog();

this.Close();

What it does basically is to Hide() the currently opened form, then it opens another form (the ShowDialog() method). It will only Close() the currently hidden form when the form you have just created is closed.

The problem here is: this way of doing it creates an immense thread of forms. If I need to go from frmSecond to frmThird, it will maintain the first form and the frmSecond being executed in the background, while only showing the frmThird.

Then, as the frmThird is open, if I need to get back to the first form, I would use some code like:

frmFirst first = new frmFirst();

this.Hide();

first.ShowDialog();

this.Close();

And it would create another frmFirst! Then we would have three forms being executed in the background (the first frmFirst, frmSecond, and frmThird).

This method works, but uses an increasingly amount of processing memory, which may be prejudicial for any kind of project.

Is there any alternative or add up to correct this problem?

If anything is unclear, please don't bother in letting me know.
Thank you.

If you want to get access to already created forms try using the static Application.OpenForms property. It contains a list of all of the forms currently open in your application. Documentation is here.

As an example, if you always want to keep frmFirst open and then navigate back to it when you close one of your other forms you can do this:

frmFirst existing = Application.OpenForms.OfType<frmFirst>().FirstOrDefault();

if (existing != null)

    existing.Show();

You would need to remove your this.Close() calls for this to work.

To free the memory you need to dispose the form using the Dispose method when it is no longer needed.

Seems like you have a desing error here

Then, as the frmThird is open, if I need to get back to the first
form, I would use some code like:

frmFirst first = new frmFirst();

this.Hide();

first.ShowDialog();

this.Close();

This will leave the original created frmFirst in memory, not visible, doing nothing but eating memory.

If you know you want to get back to frmFirst that was created before, why not just do this :

frmFirst.Show();

and save you lots of memory.

You have 2 choices actually

1. Hide forms and reactivate them when needed


2. Close and dispose forms, and recreate them when needed

What you are doing is creating each form over and over again, without getting rid of the prior created forms. Hence you need lots of memory for hidden forms...