Single instance windows forms application and how to get reference on it?

Question

I have a Windows Forms application that allows only one instance to be running at the time. I have implemented Singleton by using Mutex. The Application must be startable fr

Answer 1

I think the easiest way is the following

see the link

http://codenicely.blogspot.com/2010/04/creating-forms-object.html

Answer 2

The .NET framework offers a very good generic solution for this. Check the bottom of this MSDN magazine article. Use the StartupNextInstanceHandler() event handler to pass arbitrary commands to the running instance, like "quit".

Answer 3

This is a somewhat quick-and-dirty solution which you would probably want to refine:

[STAThread]
static void Main()
{
    var me = Process.GetCurrentProcess();
    var otherMe = Process.GetProcessesByName(me.ProcessName).Where(p => p.Id != me.Id).FirstOrDefault();

    if (otherMe != null)
    {
        otherMe.Kill();
    }
    else
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
    }
}

If an instance of the app is already started, that process is killed; otherwise the app starts normally.

Answer 4

Is this not over complicating things ? Rather than closing the existing instance and starting a new one, can you not just re-activate the existing instance? Either way round the code below should give you some ideas on how to go about it...?

Process thisProcess = Process.GetCurrentProcess();
        Process[] allProcesses = Process.GetProcessesByName(thisProcess.ProcessName);
        Process otherProcess = null;
        foreach (Process p in allProcesses )
        {
            if ((p.Id != thisProcess.Id) && (p.MainModule.FileName == thisProcess.MainModule.FileName))
            {
                otherProcess = p;
                break;
            }
        }

       if (otherProcess != null)
       {
           //note IntPtr expected by API calls.
           IntPtr hWnd = otherProcess.MainWindowHandle;
           //restore if minimized
           ShowWindow(hWnd ,1);
           //bring to the front
           SetForegroundWindow (hWnd);
       }
        else
        {
            //run your app here
        }

There is another question about this here