ARCHITECTURE.md

Architecture

Nine classes in one package, in three layers: entities that model the university, support classes for input and storage, and a main class that runs the loop.

Layers#

EntitiesModel the people, courses and grades.

User Student Instructor Administrator Course Assessment

SupportInput, validation, menus and file storage.

Helpers dataManager

ApplicationThe loop that ties it together.

SchoolCourseEnrolmentSystem

Class map#

Class index#

Class Kind Responsibility Lines

User abstract class Abstract generic base for every account type. 91 source

Student class Enrols, drops, checks credit hours and views grades. 209 source

Instructor class Views rosters, grades students and edits course details. 210 source

Administrator class Manages accounts, courses and instructor assignments. 192 source

Course class A course: capacity, credit hours, status and roster. 183 source

Assessment class One grade: student × course × exam type → score. 190 source

Helpers utility class Shared input, validation, login, menus and multi-step flows. 806 source

dataManager singleton class Singleton storage layer: five lists, five text files. 696 source

SchoolCourseEnrolmentSystem main class Entry point: load, register the default admin, loop, save. 195 source

Class	Kind	Responsibility	Lines
`User`	abstract class	Abstract generic base for every account type.	91	source
`Student`	class	Enrols, drops, checks credit hours and views grades.	209	source
`Instructor`	class	Views rosters, grades students and edits course details.	210	source
`Administrator`	class	Manages accounts, courses and instructor assignments.	192	source
`Course`	class	A course: capacity, credit hours, status and roster.	183	source
`Assessment`	class	One grade: student × course × exam type → score.	190	source
`Helpers`	utility class	Shared input, validation, login, menus and multi-step flows.	806	source
`dataManager`	singleton class	Singleton storage layer: five lists, five text files.	696	source
`SchoolCourseEnrolmentSystem`	main class	Entry point: load, register the default admin, loop, save.	195	source

Listings come from the project report and were re-indented when extracted from the PDF, so wrapping may differ slightly from the original files.

Design decisions#

Singleton storage

dataManager.getInstance()

One synchronized factory method means every part of the program shares the same five lists.

Self-typed generics

User<T> / <T extends User<T>> T login(...)

Each subclass passes itself as T, so one login flow in Helpers returns a Student, Instructor or Administrator with no casts.

Predicate validators

updateFieldWithPrompt("email", value, Helpers::ValidateEmail)

Validators are passed as method references, so one prompt method handles every field.

Enums for fixed choices

Role · EnrollmentStatusEnum · ExamType

Roles, Open/Closed and exam types can only take valid values, and valueOf() parses them from the files.

Safe removal

Iterator<Student> it = list.iterator(); it.remove();

Removing through an Iterator avoids a ConcurrentModificationException while looping.

Plain-text persistence

String.join("|", ...) / line.split("\\|")

Human-readable files with no database dependency, at the cost of indexing, concurrency and integrity checks.

When data is saved#

Only a few actions write to disk immediately. Everything else waits for saveAllData() at exit, which is why closing the window loses work (see Known issues).

Who Action File Written

Start-up Register the default admin administrators.txt immediately

Student 7 · Update personal information students.txt immediately

Instructor 3 · Update course information courses.txt immediately

Instructor 4 · Update personal information instructors.txt immediately

Admin 9 · Update Student Info students.txt immediately

Admin 10 · Update Instructor Info instructors.txt immediately

Student 2 · Enroll / 5 · Drop students.txt on exit only

Instructor 2 · Grade assignments assessments.txt on exit only

Admin 1, 2 · Add / remove students students.txt on exit only

Admin 4, 5 · Add / remove instructors instructors.txt on exit only

Admin 7, 8, 11 · Add / close course, assign instructor courses.txt on exit only

Exit Type exit at the role prompt all five files immediately

Who	Action	File	Written
Start-up	Register the default admin	`administrators.txt`	immediately
Student	7 · Update personal information	`students.txt`	immediately
Instructor	3 · Update course information	`courses.txt`	immediately
Instructor	4 · Update personal information	`instructors.txt`	immediately
Admin	9 · Update Student Info	`students.txt`	immediately
Admin	10 · Update Instructor Info	`instructors.txt`	immediately
Student	2 · Enroll / 5 · Drop	`students.txt`	on exit only
Instructor	2 · Grade assignments	`assessments.txt`	on exit only
Admin	1, 2 · Add / remove students	`students.txt`	on exit only
Admin	4, 5 · Add / remove instructors	`instructors.txt`	on exit only
Admin	7, 8, 11 · Add / close course, assign instructor	`courses.txt`	on exit only
Exit	Type exit at the role prompt	`all five files`	immediately

Project layout#

treeSchoolCourseEnrolmentSystem/
├─ src/schoolcourseenrolmentsystem/
│  ├─ User.java  Student.java  Instructor.java  Administrator.java
│  ├─ Course.java  Assessment.java
│  ├─ Helpers.java  dataManager.java
│  └─ SchoolCourseEnrolmentSystem.java   ← main()
├─ students.txt  instructors.txt  administrators.txt
├─ courses.txt  assessments.txt         ← written next to the program
└─ web/                                 ← this website