Problem with Disposed objects [Resolved]

[Porsche944]

Hey everyone,
I created a program that searches Active Directory. I built the release version and it runs as it should. The problem comes up if I attempt to reopen the search form from the system tray again I get this error.

"Cannot access a disposed object named "Search"

I think the problem is coming up when the garbage collection runs it deletes the Search Form object out of memory. How can I prevent this from happening in my program?

"just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.ObjectDisposedException: Cannot access a disposed object named "Search".
Object name: "Search".
at System.Windows.Forms.Control.CreateHandle()
at System.Windows.Forms.Form.CreateHandle()
at System.Windows.Forms.Control.get_Handle()
at System.Windows.Forms.Control.SetVisibleCore(Boolean value)
at System.Windows.Forms.Form.SetVisibleCore(Boolean value)
at System.Windows.Forms.Control.set_Visible(Boolean value)
at Active_Directory_Advanced_Search.sysTray.ShowFormSelect(Object sender, EventArgs e)
at Active_Directory_Advanced_Search.sysTray.NotifyIcon_DoubleClick(Object sender, EventArgs e)
at System.Windows.Forms.NotifyIcon.OnDoubleClick(EventArgs e)
at System.Windows.Forms.NotifyIcon.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.NotifyIcon.WndProc(Message& msg)
at System.Windows.Forms.NotifyIconNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)"

[RobDog888]

Either create a new instance each time you want to show it (since you are disposing it upon close of that form, probably) or create
a public var set to the search form and create it on first use. Then just do a .Show/.Hide instead of disposing of it.

[Porsche944]

How should I change my code to just show and hide the form ?

Here is my code as it is now.

In System Tray Form

    Private Sub ShowFormSelect(ByVal sender As Object, ByVal e As System.EventArgs)
        'Display SettingsForm dialog if it is not already displayed.
        If mSettingsForm Is Nothing Then
            mSettingsForm = New Search
            mSettingsForm.ShowDialog()
        Else
            If mSettingsForm.Visible = False Then
                mSettingsForm.Visible = True
            End If
            mSettingsForm.Activate()
        End If
    End Sub

In system tray form Declarations

    Private mSettingsForm As Search

Under what event in the search form should I put
me.hide ?

[RobDog888]

In the close button's click event, but its being shown modally so that will hold up the process.
Will it messup any of your other code to just do a .Show instead of a .ShowDialog?

You could hide the calling form from the form that is calling the search and show it again upon the close buttons click
event in the search form.

[Porsche944]

No I went ahead and changed it from showdialog to show. I can't find the event for the on click close command. All I see in the event viewer is closed and closing i tried me.hide in each but i still get this error.

[RobDog888]

You should do something like...

'Behind search form
Private Sub frmSearch_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
    Me.Hide()
    otherform.Show
End Sub
 
'Behind main form
Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click
    ShowFormSelect(sender, e)
    Me.Hide
End Sub