The use of C# timer

Namespace: using System.Timers;

Create a timer in the class: private Timer timer = new Timer(3000);

Use the timer in the program:

//start the timer
            timer.Elapsed += new ElapsedEventHandler(timer_Elapsed);
            timer.Start ();

void timer_Elapsed(object sender, ElapsedEventArgs e)
        {
            timer.Stop();
            Dispatcher.Invoke(DispatcherPriority.Normal, (Action)delegate ()
            {
                this.Close();
            });
        }

It is hereby recorded for beginners to use.