public static void ChangeCustomer(String[] args)
    {
            String userID = args[3];                
            Customer existingCustomer = GetCustomer(userID);
            
            if(existingCustomer == null)
            {
            	System.out.println("No user has ID: " + args[3] + "! Please try again!");
            	return;
            }
            
            //sample command
            //$ h21 user change --user_id [ --first_name --last_name --email [ --cc_number --expiration_date --security_code --phone ]]
            //index should start at 4
            for(int i=4; i<args.length; i+=2){
                    if(args[i].equals("--first_name")){existingCustomer.setFirstName(args[i+1]);}
                    else if (args[i].equals("--last_name")) {existingCustomer.setLastName(args[i+1]);}
                    else if (args[i].equals("--email")) {existingCustomer.setEmail(args[i+1]);}
                    else if (args[i].equals("--cc_number")) {existingCustomer.setCcNumber(args[i+1]);}
                    else if (args[i].equals("--expiration_date")){existingCustomer.setExpirationDate(args[i+1]);}
                    else if (args[i].equals("--security_code")){existingCustomer.setSecurityCode(args[i+1]);}
                    else if (args[i].equals("--phone")){existingCustomer.setPhone(args[i+1]);}
            }                                                                                
    }