CODEWITHSUNDEEP
.netwinforms
Slauma
Slauma

Reputation: 177163

How do I exit a Windows Forms application immediately after displaying a MessageBox when an error on startup occurs?

At startup of a Windows Forms application I read a XML file. If this file doesn't exist or doesn't have a certain setting I want to display a MessageBox to the user indicating the problem and then close the application.

I tried to do that in the Load event of the main form with Application.Exit() like so:

private void MainForm_Load(object sender, EventArgs e)
{
    if (!StartupSettingsCorrect())
    {
        MessageBox.Show("Blabla... Can't start application.");
        Application.Exit();
    }

    // Other stuff...
}

But this doesn't seem to be clean. (The application is running but "invisible" with no form on the screen.)

What is instead the best way and place for a clean shutdown in this situation?

Thank you for help in advance!

Upvotes: 5

Views: 7342

Answers (7)

Praveen Vinny
Praveen Vinny

Reputation: 2408

Form.Dispose() can be used to completely free up the resources held by that program.

private void MainForm_Load(object sender, EventArgs e)
{
    if (!StartupSettingsCorrect())
    {
        MessageBox.Show("Blabla... Can't start application.");
        Me.Dispose();
    }

    // Other stuff...
}

I think, this would be fine for clearing the resources and for exiting an application completely.

Upvotes: 0

Xavi
Xavi

Reputation: 11

Environment.Exit() is recommended only for Console Applications.

For Winforms, use Application.Exit()

If you want to exit program before loading the main form, the example provided by "colinsmith" is good!

Upvotes: 1

Evolved
Evolved

Reputation: 609

In Form_Load:

Me.Visible = False

if yourCheckNotOk then
  MessageBox("check failed..")
  Me.close()
else
  ...
  ...
  ...
  Me.Visible = True
end if

Tested with VS 2010. (Assuming Shutdown mode is set to "When startup form closes" in your project settings and Load event is the event of your startup form)

Upvotes: 0

HTTP 410
HTTP 410

Reputation: 17618

The Application.Exit method stops all running message loops on all threads and closes all application windows. But depending on when it's called, it doesn't necessarily force the process to end. If you call Application.Exit before loading your main form, that should work.

Another solution would be to close your main form - the rest will then be handled for you. This is the equivalent to using Application.Shutdown.

Otherwise you can use Environment.Exit. I believe this terminates the process without unwinding the stack and without executing finally blocks. So it's very rude, but this may not be an issue in your current context.

Upvotes: 1

Colin Smith
Colin Smith

Reputation: 12540

This technique avoids starting up the main form in the first place, if some pre-requisites haven't been met.

You're application won't be unloaded until you come out of the MessageBox though.

static class Program
{
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        if (!StartupSettingsCorrect())
        {
            MessageBox.Show("Blabla... Can't start application.");
        }
        else
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }
}

Upvotes: 2

TLiebe
TLiebe

Reputation: 7986

Read the XML file in the Main method of the Program.cs file (should be autogenerated for you). If you get an error then don't load the form.

    static void Main ()
    {
        if ( !StartupSettingsCorrect())
        {
            MessageBox.Show( "Blabla... Can't start application." );
        }
        else
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault( false );
            Application.Run( new MainForm() );
        }
    }

Upvotes: 3

dandan78
dandan78

Reputation: 13894

Environment.Exit() should do the trick. At least it worked for me in the situation you described.

According to MSDN, this method

Terminates this process and gives the underlying operating system the specified exit code.

Upvotes: 12

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