I'd like to properly close some sockets, and be able to tell the server that we're closing, but if the application is closed then the sockets are all just closed and on occasion files are left locked. How can I run a method when my application is closed?
This is going to go into a library that will be used in a forms app.
If its a Windows Forms application you can give focus to the form, click the events lightning bolt in the properties window, and use the Form Closing event.
this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(OnFormClosing);
private void OnFormClosing(object sender, FormClosingEventArgs e)
{
// Your socket logic here
}
Also if you need to intercept the form being closed set the Cancel property to true:
e.Cancel = true;
I would implement IDisposable on the classes that use these resources. Dispose can then be called explicitly from whichever shutdown method the application type supports (OnFormClose, OnStop, Application_End, ...).
Are you talking about a WinForms app? If so, use the FormClosing event on your main form.
I'm not sure if it's the best place for it, but you can tell your process is closing by hooking AppDomain.ProcessExit. It's fine for cleanup, but I don't think it's a good time to be sending any messages out. :)
Related
I have a form app with two Forms. In the second form I have in the right corner the x button. How I can make when I make click on this button to close the app, not just hide the Form2 window?
First you need to catch the event. To do that, set an event handler on the child form's FormClosing event.
Then there are several options:
"Brute force" termination using Process.Kill().
This will terminate the process without letting any cleanup code to run. It has an effect like ending a process through the task manager. You can get the current process with Process.GetCurrentProcess. Use like this:
Process.GetCurrentProcess().Kill();
"Gentle" termination by way of closing all windows using Application.Exit().
This will close all message pumps and windows, but will do so while allowing normal cleanup code to run. It does not however guarantee the process will be terminated, for example if a forgound thread is still active after message loops are done. Use like this:
Application.Exit();
Communicate intentions to the main thread.
This is a design solution, not a "line of code" you put somewhere. The idea is that the 2 classes (of the 2 forms) have some communication mechanism (via message, events or whatever you see fit and probably already use), and the child form notifies the parent form the user wants the exit the application. Then it's up to the main form to cleanup everything, close all forms (itself and others), and exit the process normally. This is the cleanest and preferred method, but requires a proper design and more code.
If you are using form the simplest is using
this.Close(); or Application.Exit();
I have a simple WinForms application that runs in the system tray. Is it possible to password protect the program from closing if a user tries to close it from task manager?
Ideally I want to keep a user from closing the process but if windows is restarted, I want it to close without being prompted. Much like antivirus programs.
If a user has the correct permissions they will be able to kill your process from the Task Manager.
That said as #fujiFX mentions in his comment the FormClosing event is a good start and better than nothing.
The FormClosing event occurs as the form is being closed. When a form is closed, it is disposed, releasing all resources associated with the form. If you cancel this event, the form remains opened. To cancel the closure of a form, set the Cancel property of the FormClosingEventArgs passed to your event handler to true.
It's hard to do, but you can create two applications, one is main program and two is helper. If helper is killed, then main app restarts it. If main app is killed, then helper restarts main app.
You can make this verification on YourService.Stop method (assuming you're using a Windows Service thus inheriting from ServiceBase), but as far as I know you cannot prevent the user from killing the proccess, just to close the app (two different things in Windows).
I'm writing a multi form application, and I'd like to be able to close Form1 with out the application closing.
Right now i'm using this.Hide to hide the form. Is there a way to set it so i can close any form, or the application should only exist when all the forms are closed?
I think i remember seeing something like that at one point, but that might not have been visual studio and c#.
In your Program.cs file you have a line like Application.Run(new Form1()). Replace it with
var main_form = new Form1();
main_form.Show();
Application.Run();
Also you need to close application explicitly by call Application.Exit() where you want.
One strategy is to do something like the following:
private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
if (Application.OpenForms.Count == 0)
Application.Exit();
}
}
If you place this on all of your forms, when the last one closes, the application will exit.
A multiform aplication should have a clear EXIT option (either by menu, toolbar), since you can not know that the user wants to close the program when the last window is closed (i supose that the user could go to the File/Open and open new windows)
An aplication that does something automatically that the user did not asked for can used frustration/confusion and spend time reopening the aplication.
Even the user can think that the application somehow crashed since he did not close it.
Based on your coments it's a single flow kind of application
I suggest that you implement the typical wizard interface on a single form with the BACK, NEXT, CANCEL buttons.
When the desired state has been reached, for example enough information has been gathered , the NEXT button is changed to a FINISH button.
Any time the user presses the CANCEL/FINISH button the window will close
And if you still want multiform you could still have it, in this you could have multiple flows at the same time and just finish or cancel the one that you want.
I'm writting an WPF application using the mvvm toolkint.
In the main windows I have a command in a button that open another window using:
catView.ShowDialog();
Well, I close that window (using a close button or the X) and when I close the main window, the app is still running and I have to kill it.
If I don't open the second window, the app shutdown normally.
Why if I open another window I can't close the app normally?
I have this in the close button of the second window:
this.DialogResult = true;
this.Close();
On the other hand, I start the app in this way (mvvm toolkit way):
Views.MainView view = new Views.MainView();
view.DataContext = new ViewModels.MainViewModel();
view.Show();
Thank you very much.
The problem is probably unrelated to opening and closing the window but is somthing inside that window.
This usually happens when you have another thread still running when you close the application, check for anything that might be creating a new thread inside the window's code (including System.Threading.Thread, ThreadPool, BackgroundWorker and 3rd party components), make sure all background threads shut down before closing the application (or if you can't shut them down at least mark them as background threads).
Also look for anything that can open another (invisible) window, it's common to use window messages to an invisible window as an inter-process communication mechanism, again look for 3rd party code that might be doing that.
Nir is correct, a thread is probably still running in your other window.
You can fix this by terminating the application's thread dispatcher when the window closes.
public Window1()
{
InitializeComponent();
// This line should fix it:
this.Closed += (sender, e) => this.Dispatcher.InvokeShutdown();
}
I'm happy to be corrected if this is not the right way to do things. Worked well for me though.
PS.
If your other window is designed to run in a different thread, then read this by Eugene Prystupa:
running-wpf-application-with-multiple-ui-threads
I don't know if this is causing your issue or not, but you don't need the call to Close() in your second window. Setting the DialogResult automatically closes the window.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Why is Application.Restart() not reliable?
I pulled the code straight from MSDN. This updates my application, but Restart() does not work. The application shuts down, but it does not restart.
I added a MenuItem to my Form to validate that Restart() works at all:
private void restartToolStripMenuItem_Click(object sender, EventArgs e)
{
Application.Restart();
}
This will restart the application (of course, it performs no updates and is user initiated, so it is fairly useless).
I have nothing else going on with this application. No event handlers for the Form on shutdown, nothing. This is the most basic Windows Forms application I could build (it just displays a resource JPEG in an ImagePanel).
Why does Restart() not work here?
Is your application Windows Forms or WPF? Because Application.Restart only exists in the Windows Forms Application object (System.Windows.Forms.Application) and is not supported by applications running under the WPF Application (System.Windows.Applications). You can still call it, but as the application context is different, it doesn't work.
If you are using a Mutex, or something of the like to ensure only one instance of the application is running at a time, that be causing this issue.
Try wrapping it with a BeginInvoke just in case it's not on the main STA thread.
Are you sure that you're calling Application.Restart from the main form? If you call a form with .ShowDialog and then from that form call Application.Restart, it won't work because the .ShowDialog causes the dialog form to run on a separate thread.
Try to raise a new process, maybe that can workaround it:
Process.Start(Application.ExecutablePath);