Decorating your Class Diagram
 

• You can also assign visibility to the methods and attributes.
• + public
• - private
• # protected
• You can also assign associations between classes.
• A line without an arrowhead represents a role.  Put the role description above the line.
• Use a darkened arrow to represent the direction of association.  Put the association above the line.
• You normally have either an association or a role, but not both.
• Multiplicity or cardinality notes the number of instances of one class that are linked with one instance of another class.
• Place the cardinality number towards the end of the association line of the class to which you are describing.
• Common cardinality includes: 1 (exactly one) 0..1 (0 or 1) 0..* (0 to many), etc.
• Composition and aggregation describes a strong relationship between two classes.  For the moment, let's ignore the differences between the two.
• For example, a car is composed of an engine.  We can say that class Car requires class Engine, the two cannot be separated to be functional.
• To denote composition, use a diamond.  Colored diamonds represent composition, while hollow diamonds represent aggregation.  But again, for our purposes, this is not very significant.
• Generalization represents inheritance.  To denote generalization, use an upward-pointing empty triangle on the superclass side of the association/role line.
• For example, Traditional and Pan extend Crust.  On class Crust, you would have an open triangle.  This would be connected with a line to classes Traditional and Pan.

Created by:  Brandan Jones December 17, 2001