VALIDATION.md

Validation & errors

Input is checked in three places: the Helpers validators before any setter runs, guards inside a few setters and loops, and try/catch blocks that keep the program alive.

Helpers.Validate*

Validators#

Each returns true or false, so prompts loop until the input passes. They are passed around as Predicate<String> method references, e.g. Helpers::ValidateEmail.

Method Passes when Passes Fails Used by

ValidateName length() > 3 Lina Haddad Bo Adding students and instructors, admin profile updates

ValidatePassword length() > 8 Student1234 secret12 Creating accounts and every profile update

ValidateEmail contains("@") && contains(".") sara.k@uni.example sara-at-uni Creating accounts and every profile update

ValidatePhoneNumber length() == 10 0500000101 05000001 Creating accounts and every profile update

ValidateAddress length() > 3 East Gate N/A Creating accounts and every profile update

Method	Passes when	Passes	Fails	Used by
`ValidateName`	`length() > 3`	Lina Haddad	Bo	Adding students and instructors, admin profile updates
`ValidatePassword`	`length() > 8`	Student1234	secret12	Creating accounts and every profile update
`ValidateEmail`	`contains("@") && contains(".")`	sara.k@uni.example	sara-at-uni	Creating accounts and every profile update
`ValidatePhoneNumber`	`length() == 10`	0500000101	05000001	Creating accounts and every profile update
`ValidateAddress`	`length() > 3`	East Gate	N/A	Creating accounts and every profile update

Phone numbers are checked for length only, so any ten characters pass. The report suggests a regular expression instead.

Guards & messages#

Where Rule Prints

Course.setCourseName Not null or empty Course name cannot be null or empty.

Course.setCourseCode Not null or empty Course code cannot be null or empty.

Course.setCapacity Greater than 0 Error: Capacity must be > 0.

Course.setCreditHours Greater than 0 Credit hours can not be <= 0

Student.setCreditLimit Not negative Must be greater than 0

Helpers.getSafeIntInput An integer was typed Invalid input. Please enter a number.

Helpers.checkValidityOfRole 1, 2 or 3 Invalid selection. Please enter 1, 2, or 3.

Instructor.gradeStudent Score 0–100 Score must be between 0 and 100.

Helpers.validatePasswordWithRetries At most 3 attempts Too many failed attempts. Returning to main menu.

main() menu switches A listed option Invalid option.

main() role prompt student, instructor, admin or exit Invalid role. Try again.

Where	Rule	Prints
`Course.setCourseName`	Not null or empty	`Course name cannot be null or empty.`
`Course.setCourseCode`	Not null or empty	`Course code cannot be null or empty.`
`Course.setCapacity`	Greater than 0	`Error: Capacity must be > 0.`
`Course.setCreditHours`	Greater than 0	`Credit hours can not be <= 0`
`Student.setCreditLimit`	Not negative	`Must be greater than 0`
`Helpers.getSafeIntInput`	An integer was typed	`Invalid input. Please enter a number.`
`Helpers.checkValidityOfRole`	1, 2 or 3	`Invalid selection. Please enter 1, 2, or 3.`
`Instructor.gradeStudent`	Score 0–100	`Score must be between 0 and 100.`
`Helpers.validatePasswordWithRetries`	At most 3 attempts	`Too many failed attempts. Returning to main menu.`
`main() menu switches`	A listed option	`Invalid option.`
`main() role prompt`	student, instructor, admin or exit	`Invalid role. Try again.`

Exception handling#

Where Catches What happens

main() Exception, around the whole loop Prints “Error: <message>” and the program ends without saving.

load* methods FileNotFoundException “<Type> file not found. Starting with empty <type> list.”

load* methods IOException “Error reading <type> file: <message>”

loadStudents NumberFormatException “Error parsing student data: <message>”

loadCourses, loadAssessments IllegalArgumentException (bad enum or number) “Error parsing course/assessment data: <message>”

save* methods IOException “Error writing <type> file: <message>”

Helpers.getSafeIntInput Any exception from nextInt() Clears the line and asks again.

Helpers flows (enrol, drop, add, update…) Exception Prints the exception's message and returns to the menu.

Instructor.gradeStudent InputMismatchException for the score “Invalid input. Please enter a number.” and asks again.

Where	Catches	What happens
`main()`	Exception, around the whole loop	Prints “Error: <message>” and the program ends without saving.
`load* methods`	FileNotFoundException	“<Type> file not found. Starting with empty <type> list.”
`load* methods`	IOException	“Error reading <type> file: <message>”
`loadStudents`	NumberFormatException	“Error parsing student data: <message>”
`loadCourses, loadAssessments`	IllegalArgumentException (bad enum or number)	“Error parsing course/assessment data: <message>”
`save* methods`	IOException	“Error writing <type> file: <message>”
`Helpers.getSafeIntInput`	Any exception from nextInt()	Clears the line and asks again.
`Helpers flows (enrol, drop, add, update…)`	Exception	Prints the exception's message and returns to the menu.
`Instructor.gradeStudent`	InputMismatchException for the score	“Invalid input. Please enter a number.” and asks again.