Class Diagram: Advanced Concepts

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Class Diagram Advanced Concepts

• Yin-Hsong Hsu

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Multiple Classification

• Single classification vs. multiple classification
• Multiple classification v.s multiple inheritance
• complete
• Useful for conceptual modeling

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Dynamic Classification

• Where an object may change its type?
• Examples
• a bank account
• a persons job
• Dynamic classification vs. static classification
• Useful in conceptual modeling

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Aggregation and Composition

• Aggregation part-of relationship ?
• Coad organization and clerk gt yes
• Rumbaugh company and employees gt no
• Composition in UML (stronger definition)
• the part object are usually expected to live and
  die with the whole

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Derivated Assocations and Attributes

• are those that can be calculated from other
  associations and attributes respectively on a
  class diagram
• Most critical on specification diagrams
• For reminding on conceptual diagrams
• For annotating fields that are used as caches on
  implementation diagrams

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Interface and Abstract Classes

• Interface vs. implementation
• Abstract methods and classes
• Generalization
• Dependence

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Windows Window
toFront( )
toBack( )
Window
X11 Window
abstract
Text Editor
toFront( )
toFront()
toBack( )
toBack()
Mac Window
myTextEditor
toFront( )
toBack( )
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Reference Objects and Value Objects

• Examples
• Value objects should be immutable
• association vs. attributes in UML
• Collections for multi-valued roles
• ordered, bag, ordered bag, hierarchy,
  dag
• Immutability
• immutable vs. read only ex. Age (birthday)
• bear in mind that people may make mistakes

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Classification and Generalization

• is a relationship ??
• Generation is transitive
• Classification is not transitive

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Qualified Associations

• An example
• In conceptual modeling
• In specification modeling
• For implementation

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Association Class

• An example

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Another form of previous diagram
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N-ary Association

• An n-ary association is an association among
  three or more classifiers

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Parameterized Class

• Parameterized class in C (template)
• a bound element, stereotype bind

Class Set ltTgt void insert (T
newElement) void remove(T newElement) ... S
et ltEmployeegt employeeSet
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Visibility

• C
• public, private, protected
• friend
• Java
• public, protected, package, private
• Smalltalk
• private (data), public (operations)
• When you are using visibility, use the rules of
  the language of which you are working