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Thread: Help with using pre-created objects and Vectors **First Post :)**

  1. #1
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    Default Help with using pre-created objects and Vectors **First Post :)**

    Hello, I am having difficulty with a question is an assinment. I have been fine with all the others but i'm having troble with a trivial issue. We need to build an order system based on the class diagram below.

    class.jpg

    As the multiplicity of Customer and Item is 0..* I am aware that we need to use a vector to store the customer and item objects. I already had a method of doing this which I thought would work but after reviewing the lecture notes and some sample code I became confused.

    This is the code provided by my tutor..

    CLASS OrderSystem
    public class OrderSystem {
        private Customer m_customer;
     
     
        public OrderSystem() {
            m_customer = new Customer(this);//create a customer and pass it a reference to this order system
            m_customer.SendOrderSystemAMessage();//send a message to the new customer
     
        }
     
        public void printMessage(String msg) {
    	System.out.println(msg);
        }
    }

    Class Customer
    public class Customer {
        private OrderSystem m_orderSystem;
     
          public Customer() {//default constructor
              // not much use as it would create a customer that has no link to the order system
        }
     
        public Customer(OrderSystem os) {//constructor with a reference to the calling object
            m_orderSystem = os;//this is now a link to the object that created this customer
        }
        public void SendOrderSystemAMessage()
     
    {
    	m_orderSystem.printMessage("message from your new customer");
    }
    }

    I believe this code is to show us how a customer object is linked to an OrderSystem object. However when i use similar code using a vector i get errors. Can anybody help me please, i've been looking at this for hours now and I seem to be getting more confused.

    Thanks a lot to everyone in advance.

    MY OrderClass

    public class OrderSystem {
     
        private Vector<Customer> m_customers;
     
     
     public OrderSystem() {
       m_customers = new Vector<Customer>();
       m_customers.SendOrderSystemAMessage();   
     
     
     }
     
      public void printMessage(String msg) {
      System.out.println(msg); //send a message to the new customer 
      }      
     
     
      public void addCustomer(String custID,String name,String address,int creditRating) {
     
        }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Help with using pre-created objects and Vectors **First Post :)**

    i get errors
    Please copy and paste here the full text of the error messages.

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