Aggregation, static variables, Model/View
Aggregation means that one class has one or more objects of another class. This
is called a "has-a" relationship between classes.
We can represent this relationship with a UML diagram. UML stands for Unified
We use a rectangle for each class. We use a line with an open diamond to designate the
In the Bakery example, the BakeryGUI has a Bakery and the Bakery has a Cake:
What is a static variable?
Model / View
What are some ways a real bakery could sell cakes to its customers?
The Bakery Program
The Bakery class provides a "model" of a bakery. The BakeryGUI class provides a "view" of (or interface to) the
Bakery. The BakeryGUI sends "messages" to the Bakery object and the Bakery sends "messages" to the Cake
objects. The Cake objects send "messages" back to the Bakery and the Bakery sends "messages" back to the
The School Supply Store Program
The SupplyStore class provides a "model" of a school supply store. The SupplyStoreGUI class provides a "view" of (or interface to the
SupplyStore). Messages are also sent between the SupplyStore object and the SupplyStoreGUI and between the SupplyStore and