How to run the mutex code in c#.net on button click event?

Question

This is my code which I had tried to run in my c# .net 3.5 program but I'm getting errors. What am I doing wrong?

error CS0115: 'Form1.Dispose(bool)': no suitable method found to override

This is the code where i got the error:

protected override void Dispose(bool disposing)
{
    if (disposing)
    {
        this._userConnectionOption = null;
        this._poolGroup = null;
        this.close();
    }
    this.DisposeMe(disposing);
    base.Dispose(disposing);
}

The actual coding starts from here:

Program.cs:

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using PU;

namespace WindowsApplication1
{
    static class Program
    {
        [STAThread]
        static void Main()
        {
            // If this program is already running, set focus
            // to that instance and quit.
            if (ProcessUtils.ThisProcessIsAlreadyRunning())
            {
                // "Form1" is the caption (Text property) of the main form.
                ProcessUtils.SetFocusToPreviousInstance("Form1");
            }
            else
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }
        }
    }
}

ProcessUtils.cs:

using System;
using System.Diagnostics;
using System.Threading;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace PU
{
    /// Summary description for ProcessUtils.
    public static class ProcessUtils
    {
        private static Mutex mutex = null;

        /// Determine if the current process is already running
        public static bool ThisProcessIsAlreadyRunning()
        {
            // Only want to call this method once, at startup.
            Debug.Assert(mutex == null);

            // createdNew needs to be false in .Net 2.0, otherwise, if another     instance of
            // this program is running, the Mutex constructor will block, and then throw 
            // an exception if the other instance is shut down.
            bool createdNew = false;

            mutex = new Mutex(false, Application.ProductName, out createdNew);

            Debug.Assert(mutex != null);

            return !createdNew;
        }

        [DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool SetForegroundWindow(IntPtr hWnd);

        [DllImport("user32.dll")]
        static extern bool IsIconic(IntPtr hWnd);

        [DllImport("user32.dll")]
        static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

        const int SW_RESTORE = 9;

        [DllImport("user32.dll")]
        static extern IntPtr GetLastActivePopup(IntPtr hWnd);

        [DllImport("user32.dll")]
        static extern bool IsWindowEnabled(IntPtr hWnd);

        /// Set focus to the previous instance of the specified program.
        public static void SetFocusToPreviousInstance(string windowCaption)
        {
            // Look for previous instance of this program.
            IntPtr hWnd = FindWindow(null, windowCaption);

            // If a previous instance of this program was found...
            if (hWnd != null)
            {
                // Is it displaying a popup window?
                IntPtr hPopupWnd = GetLastActivePopup(hWnd);

                // If so, set focus to the popup window. Otherwise set focus
                // to the program's main window.
                if (hPopupWnd != null && IsWindowEnabled(hPopupWnd))
                {
                    hWnd = hPopupWnd;
                }

                SetForegroundWindow(hWnd);

                // If program is minimized, restore it.
                if (IsIconic(hWnd))
                {
                    ShowWindow(hWnd, SW_RESTORE);
                }
            }
        }
    }

Answer 1

Create your mutex with trueas the first param.

And insert

if(!createdNew)
    mutex.Close();

before

return !createdNew;

Answer 2

By default, a windows 'Form' (in namespace System.Windows.Forms) implements IDisposable (in namespace System)

But from the error message it looks like your "Form1" does not extend the 'Form' class. Hence in your code the compiler is complaining about the absence of 'over-riddable' method.

Could you please also post your 'Form1' code ?