Ch 11 Software Development

Transcription

1 COSC 1P03 Ch 11 Software Development Introduction to Data Structures

2 COSC 1P03 Software Development Phases Analysis problem statement requirements specification system analysts inputs and outputs system model Design class specifications architectural plan system designers Coding coding according to specifications programmers Introduction to Data Structures

3 Phases of Software Development 1. analysis 2. design 3. coding 4. testing 5. debugging 6. production 7. maintenance

4 COSC 1P03 Testing unit level testing integration testing system testing testers Debugging based on test results Production trainers technical support Maintenance releases versions Documentation user documentation technical documentation technical writers Introduction to Data Structures

5 COSC 1P03 Case Study: Grade Reporting System Problem statement Analysis develop requirements specification refine statement determine inputs and outputs data required where (and when) available reports develop model select object/classes determine relationships Introduction to Data Structures

6 Problem Statement

7 COSC 1P03 Analysis Refinement marking scheme? Inputs course name bases and weights for each piece of work number of students for each student: student #, name and mark for each piece of work class list text file with class (student) information marking scheme determined by instructor at beginning of course mark data arrives over time entered by markers requires persistence binary file Introduction to Data Structures

8 Refined Problem Statement

9 COSC 1P03 Outputs final mark report to Registrar s Office for each student student number and final grade summary statistics course average other reports may be desired Introduction to Data Structures

10 Grade Report Format

11 COSC 1P03 Object/Classes nouns in problem specification candidate objects eliminate values, duplicates and irrelevant entities Model relationships between classes multiplicity Introduction to Data Structures

12 Selecting Candidate Objects

13 Candidate Objects

14 Analysis Model

15 COSC 1P03 Design Classes identified in analysis Goal: detailed class descriptions CRC card class responsibilities collaborators four cards, one per class do responsibilities for knowing first then responsibilities for doing fill in collaborators Introduction to Data Structures

16 CRC card

17 COSC 1P03 Responsibilities for Knowing Nouns in problem statement keep values others may be discovered later Assign each to a class consider real-world don t duplicate in another class Example: student number and marks in Student bases and weights in MarkingScheme average final mark in Course Introduction to Data Structures

18 Identified Fields (Values)

19 Course

20 MarkingScheme

21 Student

22 Work

23 COSC 1P03 Responsibilities for Doing Verbs phrases (actions) in problem statement remove duplicates keep relevant Is that it? Other uses of the system use cases Introduction to Data Structures

24 CandidateTasks

25 COSC 1P03 Use Cases Description of one way the system would be used E.g. computing final grades Actor individual(s) that interacts with the system Goal brief statement of the activity (reason for interaction) Steps normal (usual) sequence of steps by which the goal is achieved Extensions alternate sequence of steps for special cases Use cases Introduction to Data Structures

26 Final Grades Use Case

27 Initiate Course Use Case

28 Mark Entry Use Case

29 Update Marks Use Case

30 Mark Report Use Case

31 COSC 1P03 Doing (cont.) Add tasks identified in use cases to list of identified tasks Assign each to a class who knows data? collaboration to access data Example computing final grade Student and MarkingScheme average Course and Student Collaborators list collaborators on initiator s card Final CRC cards Introduction to Data Structures

32 Identified Tasks

33 Course

34 MarkingScheme

35 Student

36 Work

37 COSC 1P03 Detailed Design Class design responsibility for knowing instance variables responsibility for doing methods Interfaces class specifications including method declarations methods identified as doing in CRCs accessor and updater methods fill in parameter types Generalization design for future use Forms and Reports classes? Introduction to Data Structures

38 COSC 1P03 Class Design Interface Student accessor methods pieces of work by number (position in marking scheme) zero vs missing mark other methods updating marks (form) Interface MarkingScheme accessor methods pieces of work by position in marking scheme other methods applying scheme to a student s marks Introduction to Data Structures

39 COSC 1P03 Interface Work accessor methods updater methods Interface Course accessor methods class average not yet computed? other methods get student by id get next student Iterable interface & for-each Introduction to Data Structures

40 COSC 1P03 Coding Coding by programmers responsible for a specific class implementation can be done in any order may discover new classes support classes GUIs and reports Contract interface provides specification interfaces for other classes collaborators what can be used Introduction to Data Structures

41 COSC 1P03 Implementation Classes implements clause requirements Instance variables from knowing in CRCs others as needed for implementation Methods as required by interface additional support (local) methods Introduction to Data Structures

42 COSC 1P03 Main Class(es) Identified class or new maybe Course support all use cases Course could be part of something larger could have many applications involving a course new class load up, use resources from identified classes and shut down one or many e.g. for each use case Introduction to Data Structures

43 COSC 1P03 Testing Class stubs collaborator classes? class stub implements same interface so is pluggable method stubs Test harness replaces main class for testing perform desired tests test all methods and constructors repeatable Integration testing & system test Test sets sets of test data to test all possibilities test ends of ranges 0, 1 and other number of students 0, full and other marks predicted output prepare ahead of time and keep on file Introduction to Data Structures

44 COSC 1P03 Debugging, Production & Maintenance Debugging apply program to test data when unexpected output, re-code, re-design and/or reanalyze Production when satisfies all tests, release to users Maintenance correction of errors found in field (hopefully few) addition of new features re-analyze etc. change of specification re-analyze etc. Introduction to Data Structures

45 COSC 1P03 Iterators A device that allows traversal through a collection Collection interface extends Iterable<T> Collection class implements Iterable<T> Interface Iterable<T> from java.lang method iterator returns an Iterator over the ADT Interface Iterator<E> from java.util methods UnsupportedOperationException for-each Implemented in terms of an Iterator Introduction to Data Structures

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49 COSC 1P03 CourseIterator CourseImpl implements Iterable<Student> defines iterator CourseIterator implements Iterator<Student> has class package visibility (only classes in package can create a CourseIterator. Iterator references Student array in CourseImpl (theclass) passed to constructor tight coupling Iterator has its own index into theclass must keep track of current position doesn t change state of CourseImpl instance variables list it is iterating methods Introduction to Data Structures

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