Use Case and Class Diagrams for a Personal Address Book Application: 25-Comp-B11 Advanced Software Design, Undated paper, Q4

Question 4 of 28: Use Case and Class Diagrams for a Personal Address Book Application

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

17-Comp-B11 Advanced Software Design — National Exams, May 2019. 3 hours, closed book exam with two aid sheets allowed (written on both sides), no calculator permitted. The paper is organized into five parts, and candidates were instructed to answer any five (5) questions in Part I, any three (3) in Part II, any four (4) in Part III, any two (2) in Part IV, and any five (5) in Part V — only the first questions answered, in each part, as they appear in the answer book are marked. All questions carry equal weight, so the 19 questions actually marked (5+3+4+2+5 of 28) each count for 100/19 ≈ 5.26% of the paper. All 28 questions are answered below for completeness.

Reference texts: Sommerville, Software Engineering (10th ed., Pearson) — software processes, requirements engineering, design principles, testing, dependability, reuse; Pressman, Software Engineering: A Practitioner's Approach (9th ed.) — supplementary process/metrics/quality coverage; Gamma, Helm, Johnson & Vlissides (GoF), Design Patterns: Elements of Reusable Object-Oriented Software — pattern-language structure, the GoF pattern catalogue, and the "favor object composition over class inheritance" / "program to an interface, not an implementation" principles; Sebesta, Concepts of Programming Languages (12th ed.) — polymorphism, dynamic binding, visibility, encapsulation, interfaces; Bertrand Meyer, Object-Oriented Software Construction — design by contract, preconditions/postconditions/class invariants; Barbara Liskov's 1987 substitutability paper for Question 12; Stroustrup, The C++ Programming Language, for friend/access-control semantics (Question 25).

Question 12 prints “Liskpv substitution principle”, a typo in the paper; it is answered as the Liskov substitution principle.

PART I — General Principles (answer any 5 of 7)

Question 4: Use Case and Class Diagrams for a Personal Address Book Application (Part I)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Given. A single actor (the User) must be able to add, delete, edit, save, and load personal contact records.

Use case diagram: one actor, five use cases derived directly from the stated capability list.

Class diagram: AddressBookManager coordinates a collection of Contact objects and delegates persistence to FileStorage.

From use cases to classes. Each use-case bubble maps directly onto a method of AddressBookManager, the controller class owning the in-memory list of contacts: Add/Delete/Edit Contact → add()/delete()/edit(), Save/Load Address Book → save()/load(), the latter two delegated to a separate FileStorage class so persistence logic is not entangled with in-memory business logic. Each individual contact is its own Contact object (name, phone, email) rather than a raw row of fields scattered across the manager, so a contact can be validated, displayed, or serialized as a single unit — the 1..* association between AddressBookManager and Contact is exactly the "supports a user to add/delete/edit" requirement expressed structurally.