5-Oject Design & Mapping on Code__ .pptx
- 1. Object Design & Mapping onto Code By Dr. Maryam Kausar
- 2. Object Design • Purpose of object design: • Prepare for the implementation of the analysis model based on system design decisions • Transform analysis and system design models • Investigate alternative ways to implement the analysis model • Use design goals: minimize execution time, memory and other measures of cost. • Object Design serves as the basis of implementation 1-2
- 3. Terminology: Naming of Design Activities 1-3
- 4. System Development as a Set of Activities 1-4
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- 7. Object Design consists of 4 Activities 1. Reuse: Identification of existing solutions • Use of inheritance • Off-the-shelf components and additional solution objects • Design patterns 2. Interface specification • Describes precisely each class interface 3. Object model restructuring • Transforms the object design model to improve its understandability and extensibility 4. Object model optimization • Transforms the object design model to address performance criteria such as response time or memory utilization. 1-7
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- 10. One Way to do Object Design • Identify the missing components in the design gap • Make a build or buy decision to obtain the missing component • => Component-Based Software Engineering: • The design gap is filled with available components (“0 % coding”). 1-10
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- 14. Creating Methods from Interaction Diagrams 1-14
- 15. Collections • One-to-many relationships are common. • For example, a Sale must maintain visibility to a group of many SalesLineItem instances. • In OO programming languages, these relationships are usually implemented with the introduction of a collection object, such as a List or Map, or even a simple array. • Java libraries contain collection classes such as ArrayList and HashMap, which implement the List and Map interfaces, respectively. 1-15
- 16. Collections 1-16
- 17. Order of Implementation • Classes need to be implemented from least-coupled to most- coupled. • E.g., • possible first classes to implement are either Payment or ProductDescription; • next are classes only dependent on the prior implementations— ProductCatalog or SalesLineItem 1-17
- 18. 1-18 SalesLineItem quantity : Integer getSubtotal() ProductCatalog ... getProductDesc(...) ProductDescription description : Text price : Money itemID : ItemID ... Store address : Address name : Text addSale(...) Payment amount : Money ... 1..* 1..* Register ... endSale() enterItem(...) makeNewSale() makePayment(...) Sale isComplete : Boolean time : DateTime becomeComplete() makeLineItem(...) makePayment(...) getTotal() ... 1 1 1 1 1 1 * 1 2 3 4 5 6 7
- 19. Activity 1-19
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