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(643 Week 8/15 Outline: Class Diagrams) (by Liping Liu) Class Diagram: A graphical model representing conceptual objects and their relationships
Two Types of Relationships:
Inheritance:
Instance Level: Child objects are special kinds of a parent object (is-a relationship)
Class Level: Child classes are sub classes of a parent class
Wrong: A child object is contained in a parent object (why?)
Example 1:
Employee, FullTimer, and PartTimer
Account, Checking, and Savings
Encapsulation Principle Revisit:
private data for parent class must be changed into protected one
behavioral members must be changed into virtual if child class needs to change their implementation... more >>
(643 Week 9/15 Outline: Advanced Class Diagrams and Association Classes Implementation) (by Liping Liu) Review: Homework
Continue: code ApplyInterest() function
Lecture 1: Advanced Association: Composition and Aggregation:
A special kinds of association that model object containment relationship (not class containment, why?)
Composition is stronger than aggregation: composition means exclusive containment whereas aggregation means shared containment
Examples: Car - Engine - Cylinder, Building-Room-Wall, Course -Section - Student - Prerequisite, Directory - File
Implementation:
C++ uses pointers for aggregation so that when the host is destroyed, the contained objects do not have to be destroyed
C++ uses regular variables for composition so that, when the host is destroyed, the contained objects will be destroyed too
Java/C# does not have the concept of pointers and so there is no difference in implementation
Lecture 2: Association Objects and Classes
It is used for capturing data that describe associations... more >>
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