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Object Oriented Analysis and Design

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The very fundamentals of object oriented development. Understanding real world cases and representing them as objects having state and behaviour.

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Object Oriented Analysis and Design

  1. 1. Object Oriented Programming Concepts Analysis + Design
  2. 2. What’s in store… <ul><li>Real world problems  software solution </li></ul><ul><li>Functionality – Requirements/Use-cases </li></ul><ul><li>Object Oriented [OO] Concepts </li></ul><ul><li>Unified Modeling Language [UML] </li></ul><ul><li>Simple Design Pattern </li></ul>
  3. 3. Real World Problems  Software Solutions <ul><li>1. Functionality - The code should do what it’s supposed to do </li></ul><ul><li>2. Analysis and Design - Application of basic OO concepts </li></ul><ul><li>3 . Frameworks & Design Patterns – Strive for a maintainable and scalable solution </li></ul>
  4. 4. Functionality – Requirements & Use-cases <ul><li>Requirements set out the final expectations from the system </li></ul><ul><li>Use-case enumerates in detail the steps the system should take </li></ul><ul><li>Use-case has a single goal </li></ul><ul><li>Every use-case has a start and stop condition, an external initiator and clear value </li></ul>
  5. 5. Functionality – Requirements & Use-cases <ul><li>A </li></ul><ul><li>B </li></ul><ul><li>C </li></ul><ul><li>… </li></ul><ul><li>UC 1 </li></ul><ul><li>UC 2 </li></ul><ul><li>UC 4 </li></ul><ul><li>UC2 </li></ul><ul><li>UC3 </li></ul><ul><li>UC4 </li></ul><ul><li>UC1 </li></ul><ul><li>UC4 </li></ul><ul><li>UC5 </li></ul><ul><li>UC6 </li></ul>Requirements
  6. 6. OO Concepts <ul><li>Everything is an Object </li></ul><ul><li>Everything consists of objects </li></ul>
  7. 7. OO Concepts – I N H E R I T A N C E <ul><li>Build classes based on other classes </li></ul><ul><li>Avoid duplicating and repeating </li></ul><ul><li>Inherit behaviour and change [ override ] if required </li></ul><ul><li>Sub-class should be substitutable for parent class </li></ul>
  8. 8. OO Concepts – P O L Y M O R P H I S M <ul><li>Change behaviour without changing code </li></ul><ul><li>Allows a sub-class to stand-in for another class </li></ul>
  9. 9. OO Concepts – E N C A P S U L A T I O N <ul><li>Protect information in your code from being used incorrectly </li></ul><ul><li>Object = state + behaviour </li></ul><ul><li>Also known as Information Hiding or Separation of Concerns </li></ul><ul><li>Duplicate code is an indicator </li></ul>
  10. 10. OO Concepts – C O M P O S I T I O N <ul><li>Loose coupling between objects </li></ul><ul><li>Greater flexibility </li></ul><ul><li>Code changes don’t lead to cascading code breakage </li></ul><ul><li>Better encapsulation </li></ul>
  11. 11. Unified Modeling Language – U M L <ul><li>Purely representational </li></ul><ul><li>Programming language independent </li></ul><ul><li>A notational set based language and NOT a methodology </li></ul><ul><li>Fits easily into any company’s way of functioning </li></ul><ul><li>Conveys information through a wide set of diagrams </li></ul><ul><ul><li>Use-case diagram </li></ul></ul><ul><ul><li>Class diagram </li></ul></ul><ul><ul><li>Sequence diagram </li></ul></ul><ul><ul><li>State-chart diagram </li></ul></ul><ul><ul><li>Activity diagram </li></ul></ul><ul><ul><li>Component diagram </li></ul></ul>
  12. 12. U M L – Use-Case Diagram <ul><li>Illustrates a unit of functionality </li></ul><ul><li>Helps visualize functional requirements of a system </li></ul><ul><li>Include relationships of actors [users] to processes </li></ul>
  13. 13. U M L – Class Diagram <ul><li>Shows the static structures and relationships of a system </li></ul><ul><li>Can be used to display logical groupings/classifications </li></ul><ul><li>Also used to depict implementation classes </li></ul><ul><li>Both the state and behaviour of classes captured </li></ul><ul><li>Relationships between classes also important </li></ul>
  14. 14. U M L – Sequence Diagram <ul><li>Depicts in detail the flow of control through a use-case </li></ul><ul><li>Consists of 2 dimensions – </li></ul><ul><ul><li>Horizontal – shows sequence of calls/messages in time order of occurrence </li></ul></ul><ul><ul><li>Vertical – the object instances to which messages are sent </li></ul></ul><ul><li>Sequence of flow starts at the top left corner </li></ul>
  15. 15. A Design Pattern – D E L E G A T I O N <ul><li>An object outwardly exhibits a behaviour – which is performed by another object </li></ul><ul><li>Better encapsulation </li></ul><ul><li>Impact of code changes minimised </li></ul><ul><li>Sometimes referred to as aggregation </li></ul><ul><li>Example – A stack built on top of a list </li></ul>
  16. 16. So, WHAT MAKES GOOD CODE?
  17. 17. References <ul><li>UML Basic: An Introduction [IBM] </li></ul><ul><li>Head First - Object Oriented Analysis and Design </li></ul><ul><li>Wikipedia </li></ul>

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