Class Relationships

Please read these two resources to have a better understanding of class relationships

• http://creately.com/blog/diagrams/class-diagram-relationships/ focus on association, composition/aggregation (depends on your IA), multiplicity and inheritance. http://www.infoworld.com/article/3029325/application-development/exploring-association-aggregation-and-composition-in-oop.html (link title explains itself)

For more resources on the principles of OOP and UML diagrams, click here.

OOP Principles and UML

These are my favourite explanations (so far) regarding the principles of OOP: Abstraction, Encapsulation, Inheritance and Polymorphism. They are most important to understand and remember, so study and practice them well. The links have page names (at the end of the link) that are self-explanatory.

• http://codebetter.com/raymondlewallen/2005/07/19/4-major-principles-of-object-oriented-programming
• http://beginnersbook.com/2013/03/oops-in-java-encapsulation-inheritance-polymorphism-abstraction/
• http://www.javaworld.com/article/2076204/core-java/understanding-constructors.html

UML provides so many tools, that it can be overwhelming. So it is always useful to narrow it down and focus on what is useful for a specific task. The following resources are on UML class diagrams. You are also recommended to look into use-case diagrams, which are great for conceptual designs.

• http://pages.cs.wisc.edu/~hasti/cs302/examples/UMLdiagram.html
• http://etutorials.org/Programming/UML/Chapter+4.+Class+Diagrams+The+Essentials/
• http://etutorials.org/Programming/UML/Chapter+6.+Class+Diagrams+Advanced+Concepts/Aggregation+and+Composition/
• http://www.uml-diagrams.org/class-diagrams-overview.html
• http://creately.com/blog/diagrams/class-diagram-relationships/
• http://www.infoworld.com/article/3029325/application-development/exploring-association-aggregation-and-composition-in-oop.html
• http://pages.cs.wisc.edu/~hasti/cs302/examples/UMLdiagram.html
• http://www.tutorialspoint.com/uml/uml_class_diagram.htm
• http://www.ibm.com/developerworks/rational/library/content/RationalEdge/sep04/bell/

In terms of class relationships, you should know (according to the IBO syllabus content)

• dependency (“uses”)
• aggregation (“has a”) and
• inheritance (“is a”).

You may find the following links useful to revise these concepts. Just focus on what IBO requires among all the detailed information provided.

• http://www.conceptdraw.com/How-To-Guide/uml-class-diagram-notation
• https://en.wikipedia.org/wiki/Class_diagram