Lecture 4
Important Diagrams
1 Associations
2 Breaking down many-to-many relationships
3 Inheritance Structures
4 Inheritance for classification
5 Inheritance used properly
6 Composition
7 Further aggregation and composition examples
8 Dependencies
Associations 1
1 Bi-directional reuse can violate encapsulation and compromise reuse so that they are usually used in the preliminary stages of analysis.
2 Many-to-many associations need to be broken down usually.
Inheritance
1 Is a special kind of association
2 Can be single or multiple
3 It is possible to distinguish type inheritance from class inheritance. Type inheritance uses a dotted line like those used for “realization”
Composition 1
1 Special type of aggregation with a restriction
2 Strong ownership of parts: If the whole object is copied or deleted E.g. each square of a chessboard is exactly part of that board. If the board is copied, each square is copied.
Aggregation
A university degree has an aggregation of 60 or more units. Note also that the same unit can be offered in more than one degree simultaneously. E.g. basic programming can be offered in the IT and IS department
Aggregation 1
1 Aggregation is a conceptual notion that explains the relationship between classes at an informal level.
2 It does not explain how to implement the classes!!!
3 Aggregation explains a “loose” relationship between classes.
4 The diamond box is left empty or not filled.
Welcome to Kaizenlog.com If you're new here, you may want to subscribe to my RSS feed , Twitter You can contact us by using the contact form or submitting a comment. You can also share this post with your friends by clicking on the 'ShareThis' button above. Thanks for visiting!
Print This Post
Entries (RSS)