private int GetID()
{
var id = txtClient.Text;
if (string.IsNullOrEmpty(id))
{
throw new Exception("Please enter the id of a client.");
}
var isInt = int.TryParse(id, out var result);
if (!isInt)
{
throw new Exception("Please enter a valid value.");
}
var clients = _listener.GetConnectedClients();
if (!clients.Keys.Contains(result))
{
throw new Exception("The client with the ID " + result + " is not connected.");
}
return(result);
}