show a form after been closed

[csvax]

Hi All,

This may be a simple question but it surely borthered me a lot. Ok, i have a form A as

public frmA as new frmTypeA()


In the program, the form A is opened by
....
frmA.show
...

The problem is: after the frmA is closed, i.e., user clicks the X on the right-top of the form, the frmA gets disposed. Then, when it comes to frmA.show again, a error as " can not access a disposed object frmA" is thrown out . I tried to use the following code to solve the problem but doesn't work at all

if frmA is nothing then
frmA = new frmTypeA()
endif
frmA.show()

Any idea how to solve the problem ? I like .Net a lot , specially the OOP, shared class members, ...., etc. But under some circumstances, i miss the old VB6, the debug capability for an example.

[csvax]

I think i found the answer. Instead of using

if frmA is nothing then

should use

if frmA.isdisposed() then

[hellswraith]

Try puting this in the FormA's closing event:

e.Cancel = True
        Me.Visible = False

This will cancel the unload of the form, and just hide it. This means that the variable you have that points to a FormA object is still valid, and you can just set the visible property to true to show it again.

Since FormA will stay in memory, when you are done with it for good, make sure you call it's close event.

[csvax]

Thanks hellswraith. I should have thought using that closing event.

[Frans C]

Why would you keep every form in memory when the user closes it?
I don't consider that a good design.
Just check if it has been disposed.

I answered a similar question in this thread

[csvax]

Frans C, you are right in general. But in my case, it is kind of "background" form, i.e., i don't want it to be actually closed because i want to record all the values on the form's controls and don't want to define a group of variiables to record them.