//Creation/deletion commands
else if (mainArg.equalsIgnoreCase("buy"))
this.cmd = new BuyCmd(sender, args);
else if (mainArg.equalsIgnoreCase("display"))
this.cmd = new DisplayCmd(sender, args);
else if (mainArg.equalsIgnoreCase("remove"))
this.cmd = new RemoveCmd(sender, args);
else if (mainArg.equalsIgnoreCase("sell"))
this.cmd = new SellCmd(sender, args);
else if (mainArg.equalsIgnoreCase("exchange"))