Question

My entity contains the following private ForeignCollection attribute:

@ForeignCollectionField
private ForeignCollection<Order> orderCollection;

private List<Order> orderList;

What is the best way or usual way to avoid a having a caller use a ForeignCollection? Is there any neat way to return the Collections data to a caller?

How does the following method look? It allows a caller to access the data via a List. Would you recommend doing it this way?

public List<Order> getOrders() {
    if (orderList == null) {
        orderList = new ArrayList<Order>();
        for (Order order : orderCollection) {
            orderList.add(order);
        }
    }
    return orderList;
}

Answer 1

If it’s ok to change the signature to Collection rather than List, you could try using Collections.unmodifiableCollection().

public Collection<Order> getOrders()
{
    return Collections.unmodifiableCollection(orderCollection);
}

Otherwise, your approach of using a lazy member variable is fine (provided you don’t need synchronization). Also, note that you can just use the constructor of ArrayList to copy the values from the source collection:

orderList = new ArrayList<Order>(orderCollection);