DEV475 Mastering Object-Oriented Analysis and Design with UML ...
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DEV475 Mastering Object-Oriented Analysis and Design with UML ...

DEV475 Mastering Object-Oriented Analysis and Design with UML ... DEV475 Mastering Object-Oriented Analysis and Design with UML ...

crnarupa.singidunum.ac.rs
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12.07.2015 Views

DEV475 Mastering Object-Oriented Analysis and Design with UMLWhat Is Hierarchy?What Is Hierarchy?IncreasingabstractionAssetBankAccountSecurityRealEstateSavingsCheckingStockBondDecreasingabstractionElements at the same level of the hierarchyshould be at the same level of abstraction.Mastering Object Oriented Analysis and Design with UMLCopyright © 2003 Rational Software, all rights reserved 22Hierarchy can be defined as:Any ranking or ordering of abstractions into a tree-like structure. Kinds: Aggregationhierarchy, class hierarchy, containment hierarchy, inheritance hierarchy, partitionhierarchy, specialization hierarchy, type hierarchy. (Dictionary of Object Technology,Firesmith, Eykholt, 1995)• Hierarchy organizes items in a particular order or rank (for example, complexityand responsibility). This organization is dependent on perspective. Using ahierarchy to describe differences or variations of a particular concept provides formore descriptive and cohesive abstractions and a better allocation ofresponsibility.• In any one system, there may be multiple abstraction hierarchies (for example, afinancial application may have different types of customers and accounts).• Hierarchy is not an organizational chart or a functional decomposition.• Hierarchy is a taxonomic organization. The use of hierarchy makes it easy torecognize similarities and differences. For example, botany organizes plants intofamilies. Chemistry organizes elements in a periodic table.2 - 22

Module 2 - Concepts of Object OrientationWhat Is a Class?What Is a Class?• A class is a description of a set of objects thatshare the same attributes, operations,relationships, and semantics.• An object is an instance of a class.• A class is an abstraction in that it• Emphasizes relevant characteristics.• Suppresses other characteristics.Class+ attribute+ operation()Mastering Object Oriented Analysis and Design with UMLCopyright © 2003 Rational Software, all rights reserved 23A class can be defined as:A description of a set of objects that share the same attributes, operations,relationships, and semantics. (The Unified Modeling Language User Guide, Booch,1999)• There are many objects identified for any domain.• Recognizing the commonalties among the objects and defining classes helps usdeal with the potential complexity.• The OO principle of abstraction helps us deal with complexity.2 - 23

Module 2 - Concepts of <strong>Object</strong> OrientationWhat Is a Class?What Is a Class?• A class is a description of a set of objects thatshare the same attributes, operations,relationships, <strong>and</strong> semantics.• An object is an instance of a class.• A class is an abstraction in that it• Emphasizes relevant characteristics.• Suppresses other characteristics.Class+ attribute+ operation()<strong>Mastering</strong> <strong>Object</strong> <strong>Oriented</strong> <strong>Analysis</strong> <strong>and</strong> <strong>Design</strong> <strong>with</strong> <strong>UML</strong>Copyright © 2003 Rational Software, all rights reserved 23A class can be defined as:A description of a set of objects that share the same attributes, operations,relationships, <strong>and</strong> semantics. (The Unified Modeling Language User Guide, Booch,1999)• There are many objects identified for any domain.• Recognizing the commonalties among the objects <strong>and</strong> defining classes helps usdeal <strong>with</strong> the potential complexity.• The OO principle of abstraction helps us deal <strong>with</strong> complexity.2 - 23

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