WPF - Single Instance Application in WPF

In some scenarios launching multiple copies of the same WPF application is a problem, especially for document-based applications or server applications.

WPF does not provide a native solution for single instance applications.

Let See how to make a Single Instance Application in WPF.

Step 1

Create a WPF Application.

Step 2

Add a following code in app.xaml code behind,it is look like this

 #region Constructor

        public App()
        {
            try
            {
                if (MultipleInstance()) // Check first multiple instance of application
                {
                    MessageBox.Show("More than one instance is running");
                    System.Threading.Thread.Sleep(1000);
                    ProcessKiller(); // Kill the current process
                }
              
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);   
            }
        }

        #endregion

        #region Static Methods

        /// <summary>
        /// Check Multiple Instance
        /// </summary>
        /// <returns>Boolean</returns>
        private static Boolean MultipleInstance()
        {
            Boolean Flag = false;
            try
            {
                System.Diagnostics.Process[] ProcessObj = null; ;
                
                // Name of Process module
                String ModualName = System.Diagnostics.Process.GetCurrentProcess().MainModule.ModuleName.ToString();

                // Get a process name
                String ProcessName = System.IO.Path.GetFileNameWithoutExtension(ModualName);

                // Get all instances of Current application running on the local computer.

                ProcessObj = System.Diagnostics.Process.GetProcessesByName(ProcessName);

                if (ProcessObj.Length > 1) // if multipal application is running then it is true otherwise it is false
                {
                    Flag = true;
                }
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }

            return Flag;
        }

        /// <summary>
        /// kill the current Process
        /// </summary>
        private static void ProcessKiller()
        {
            
            try
            {
                System.Diagnostics.Process ProcessObj = System.Diagnostics.Process.GetCurrentProcess();
                ProcessObj.Kill(); // kill the current process
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
           
        }

        #endregion

Run the project

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