I have such a simple example:

public class Order 
{

 private ArrayList<Product> orders = new ArrayList<Product>();

 public void add(Product p)
 {
  orders.add(p);
 }

}

Is it aggregation or composition? I guess it's composition, because orders will be delated after delete of Order, right? Unfortunately it was a task and answer was different;/ Do you know why?

second problem:

public class Client extends Person 
{
    String adress = "";

    Orders orders = new Orders();

    public Client(String n, String sn)
    {
     name = n;
     surName = sn;
    }

    public String getAddress()
    {
     return adress;
    }
    public Orders getOrders()
    {
     return this.orders; 
    }


}

Is it Association between Client and Orders? My teacher told me that this is association, but I was wondering why it's not a aggregation/composition - he told me that aggregation or composition occur only when one class contains few instances of different class - is that right? I guess not, because e.g. car contains ONE wheel and it's aggregation I guess? What type of relation is that and why?

Greetings