Question

What does it mean when you have something as the following picture?
alt text http://img710.imageshack.us/img710/3876/3gmygrextht5dsd2c4svh1i.png

Each Customer has none, one or more Orders while each Order has only one Customer?

And in relationship to the following one:
alt text http://img28.imageshack.us/img28/4372/bod24yjzahqjlnrvjtfezax.png

What does the black diamond mean in this context? How is that black diamond called?

Thanks

Answer 1

In the first picture, an Order can only be associated to one Customer, while one Customer can have many Order‘s.

The black diamond in the second example is called a composition, or an associated relationship. Composition usually has a strong life cycle dependency between instances of the container class and instances of the contained class or classes. In your case Order is the container class and the Customer is its contained class.

Reference:

• Class diagram – Wikipedia