12.10. Image Icons

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Chapter Summary

• Developing a project involves requirements specification, system analysis, system design, implementation, testing, deployment, and maintenance. The process of designing classes calls for identifying the classes and discovering the relationships among them.

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• The common relationships among classes are association , aggregation , composition , dependency , and inheritance .

• Some guidelines for class design are cohesion , consistency , encapsulation , clarity , and completeness .

• A property shared by all the instances of a class should be declared as a static property.

• Don't mistakenly overlook static data fields or methods . A method not tied to a specific instance should be declared static.

• The difference between inheritance and aggregation is the difference between an is-a relationship and a has-a relationship.

• Both interfaces and abstract classes can be used to generalize common features. How do you decide whether to use an interface or a class? In general, a strong is-a relationship that clearly describes a parent “child relationship should be modeled using classes.

• Interfaces are more flexible than abstract classes, because a subclass can extend only one superclass but can implement any number of interfaces. However, interfaces cannot contain concrete methods.

• Sequence diagrams describe interactions among objects by depicting the time-ordering of method invocations. Statechart diagrams describe the flow of control of an object.