Thread: 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) {
 
    }
}

i get errors

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