Best practice for adding a bidirectional relation in OO model

Question

I\'m struggling to come up with a good way of adding a bidirectional relation in OO model. Let\'s say there is a Customer who can place many Orders, that is to say there is a on

Answer 1

I think the best way in this case is to delegate the responsibility for wiring to another class:

class OrderManager {
    void placeOrder(Customer c, Order o){
        c.addOrder(o);
        o.setCustomer(c);
    }
}

class Customer {
    private Set orders = new LinkedHashSet();
    void addOrder(Order o){ orders.add(o); }
}

class Order {
    private Customer customer;
    void setCustomer(Customer c){ this.customer=c; }
}