31269 Lecture Notes - Lecture 8: Class Diagram, Unified Modeling Language
Week 8 Lecture: Object Oriented Models – Class Modelling
Class Diagram
• A class diagram is a type of static structure diagram that describes the
struture of a syste, y shoig the systes lasses, their attriutes,
operations (or methods), as well as the relationships among classes/objects.
• It is the main building block of object oriented modelling.
• It is used for general conceptual modelling, as well as for detailed modelling
translating the models into programming code.
• A class is an abstract definition of an object, and is a plan or a blueprint from
which one or more objects can be created. However an object represents
real world things, both tangible and intangible.
• A class is a description of a set of objects that share the same attributes,
operations and relationships. It is graphically rendered as a rectangle which
usually includes its name, attributes, and operations in separate designated
compartments.
• A class stores its state in attributes, and the keyword to identify attributes
from a specifiatio is has idiatig hat a lass has.
• Operations describe the behaviour of a class and appear in the third
opartet. They are idiated through the a keyord.
Relationships
• There are four kinds of relationships that exist between classes:
o Associations
o Aggregation
o Composition
o Generalisations
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Week 8 lecture: object oriented models class modelling. Class diagram: a class diagram is a type of static structure diagram that describes the stru(cid:272)ture of a syste(cid:373), (cid:271)y sho(cid:449)i(cid:374)g the syste(cid:373)(cid:859)s (cid:272)lasses, their attri(cid:271)utes, operations (or methods), as well as the relationships among classes/objects. It is the main building block of object oriented modelling. However an object represents real world things, both tangible and intangible: a class is a description of a set of objects that share the same attributes, operations and relationships. Relationships: there are four kinds of relationships that exist between classes, associations, aggregation, composition, generalisations, an association is a relationship between classes that indicates a connection. It is represented as a bold unbroken line between two classes. If a library is closed, the books may still exist. 3,5,8: composition is a strong association, and is represented with a black diamond at the end of a line.
