Question

I was wondering something. If I have a class like this:

public class OrderItem {
    private Item item;
    private int quantity;
    private BigDecimal total;
}

And I have in the class Chart a List<OrderItem> orders. OrderItem is identified by its item so I was thinking if there is a method of orders I can ovveride (maybe indexOf) to check if an OrderItem exists and then retrieve it (or its index)

I’m talking about something different from using a for loop and check its item. Maybe an interface?

edit: I’m sorry I mislead the question, I forgot an important part. I need to retrieve the object.

Answer 1

Over-ride .equals() and .hashcode() in OrderItem so equality is determined by item.

You can then call indexOf(dummyOrderItem), where dummyOrderItem is a dummy object created with the correct item. You can then call get(index) to retrieve the true object.

If you use Eclipse, you can generate these methods automatically using source->generate hashCode() and equals():

@Override
public int hashCode()
{
    final int prime = 31;
    int result = 1;
    result = prime * result + ((item == null) ? 0 : item.hashCode());
    return result;
}
@Override
public boolean equals(Object obj)
{
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    OrderItem other = (OrderItem) obj;
    if (item == null)
    {
        if (other.item != null)
            return false;
    }
    else if (!item.equals(other.item))
        return false;
    return true;
}