I created 3 Windows Form in visual studio 2015.
I cant understand where to inster the timer and the peek and contain method
CashierClass - classclass CashierClass { private int x; public static string getNumberInQueue = " "; public static Queue CashierQueue; public CashierClass() { x = 10000; CashierQueue = new Queue(); } public string CashierGeneratedNumber(string CashierNumber) { x++; CashierNumber = CashierNumber + x.ToString(); return CashierNumber; } } QueuingForm - windowsformpublic partial class QueuingForm: Form { private CashierClass cashier; private int openForms; public QueuingForm(params Form[] forms) { InitializeComponent(); openForms = forms.Length; foreach(var form in forms) { form.FormClosed += (s, args) => { //When we have closed the last of the "starting" forms, //end the program. if (Interlocked.Decrement(ref openForms) == 0) ExitThread(); }; form.Show(); } cashier = new CashierClass(); } private void ExitThread() { throw new NotImplementedException(); } private void btnCashier_Click(object sender, EventArgs e) { lblQueue.Text = cashier.CashierGeneratedNumber("P - "); CashierClass.getNumberInQueue = lblQueue.Text; CashierClass.CashierQueue.Enqueue(CashierClass.getNumberInQueue); } CashierWindowsQueueProgramForm - windows formpublic partial class CashierWindowsQueuingForm: Form { Stack sn = new Stack(); public CashierWindowsQueuingForm() { InitializeComponent(); Timer refresh = new Timer(); refresh.Interval = (1 * 1000); refresh.Tick += new EventHandler(refresh_Tick); refresh.Start(); } public void DisplayCashierQueue(IEnumerable CashierList) { listCashierQueue.Items.Clear(); foreach(Object obj in CashierList) { listCashierQueue.Items.Add(obj.ToString()); } } private void btnRefresh_Click(object sender, EventArgs e) { DisplayCashierQueue(CashierClass.CashierQueue); CashierClass.CashierQueue.Dequeue(); } private void btnNext_Click(object sender, EventArgs e) { sn.Push(CashierClass.getNumberInQueue); } private void CashierWindowsQueuingForm_Load(object sender, EventArgs e) { this.Update(); } ServingForm - windows formpublic partial class ServingForm: Form { CashierClass num = new CashierClass(); public string h; public ServingForm() { InitializeComponent(); } public void DisplayCashierQueue(IEnumerable CashierList) {} private void lblServingNum_Click(object sender, EventArgs e) {} }