Page 33 - DCAP308_OBJECT_ORIENTED_ANALYSIS_AND_DESIGN

Unit 3: Class Modelling

You can, also show a class without its attributes or its operations, or the name of the class can Notes
appear by itself as shown in Figure 3.2.

Figure 3.2: Alternate Class Notations

Class Class
Class
Operations attributes

The naming conventions for classes are as follow:
Class names are simple nouns or noun phrases.

Attribute names in a class are simple nouns or noun phrases. The first word is not capitalized,
but subsequent words may be capital.
Operation names are simple verbs. As with attributes, the first word is not capitalized and
subsequent words may be capital.

3.1.2 Objects

The notation for an object is the same in basic form as that for a class. There are three differences
between the notations, which are:

Within the top section of the class box, the name of the class to which the object belongs
appears after a colon. The object may have a name, which appears before the colon, or it
may be anonymous, in which case nothing appears before the colon.

The contents of the top compartment are underlined for an object.
Each attribute defined for the given class has a specific value for each object that belongs
to that class.

You can see the notion of an object you can see in Figure 3.3.
Figure 3.3: Notation of Object

Object: Class :Class

Attribute 1 = value 1 Attribute 1 = value 1
Attribute 2 = value 2

Example: If you look around you will find many examples of real world objects such as
your books, your desk, your television, etc.

Notes Everything that the software object knows (state) and can do (behaviour) is expressed
by the variables and the methods within that object. In other words, all the objects share
states and behaviour. Let us say that a software object that models your real world bicycle
would have variables that indicated the bicycle’s current state: its speed is 20 mph, and its
current gear is the 3rd gear, etc.

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