• Overview
• Build and Output
  • Output
  • Sample Output
• Class Diagram
• Creational Design Patterns
  • Singleton
  • Builder
• Structural Design Patterns
  • Bridge
  • Composite
• Behavioral Design Patterns
  • Observer
  • Strategy
• Implementation Notes
  • Assumptions
  • Notes

This is an application that simulates a department (swith focus on the Computer Science Department) of a university. There is a class hierarchy for the students and employees along with their responsibilities as well as the artifacts that each person interacts with.

The purpose of the project is to demonstrate the software design patterns in the class.

Outside of using JUnit to show output and Spotless for automatic formatting of code, the application was deliberately implemented to be self-contained and not to use any other third-party library dependencies to highlight that every design pattern is implemented from the ground up.

The application uses Gradle, to build it:

$ gradle build 

The output of the application runs under a JUnit test, so you can simply run using Gradle:

$ gradle test 

This is the sample output that simulates enrolling and dropping classes as well as the waitlist use case:

INFO: 0 containers and 3 tests were Method or class mismatch
INFO: Adding program Certificate Program Web Application Development
INFO: Adding program Undergraduate Program Computer Science
INFO: Adding program Graduate Program Software Development
INFO: Setting Tony Stark as Chairperson
INFO: Setting Peter Parker as Graduate advisor for 2022
INFO: Setting Steve Rogers as Undergraduate advisor for 2022
INFO: Adding Thor Odinson as full-time faculty
INFO: Adding Suresh Kalathur as full-time faculty
INFO: Adding Wanda Maximoff as full-time faculty
INFO: Adding Pietro Maximoff as part-time faculty
INFO: Adding Simon Williams as part-time faculty
INFO: Adding Henry Pym as part-time faculty
INFO: Added course offering: Class offering for [Data Structures and Algorithms] Semester [1] Professor [Thor Odinson] Limit [2]
INFO: Added course offering: Class offering for [Software Design and Patterns] Semester [1] Professor [Suresh Kalathur] Limit [2]
INFO: Added course offering: Class offering for [Mobile Application Development with Android] Semester [2] Professor [Thor Odinson] Limit [2]
INFO: Added course offering: Class offering for [Database Design] Semester [2] Professor [Suresh Kalathur] Limit [2]
INFO: Mailbox [Tony Stark] receives message: Message from [Mailroom] Subject [Course Offering Full] Message [Course offering Class offering for [Software Design and Patterns] Semester [1] Professor [Suresh Kalathur] Limit [2] is full]
INFO: Mailbox [Will Turner] receives message: Message from [Mailroom] Subject [Waitlist notification] Message [You are waitlisted for Class Class offering for [Software Design and Patterns] Semester [1] Professor [Suresh Kalathur] Limit [2]]
INFO: Mailbox [Tony Stark] receives message: Message from [Mailroom] Subject [Course Offering Full] Message [Course offering Class offering for [Software Design and Patterns] Semester [1] Professor [Suresh Kalathur] Limit [2] is full]
INFO: Auto-enroll Will Turner to Class offering for [Software Design and Patterns] Semester [1] Professor [Suresh Kalathur] Limit [2] successful

PlantUML

The pattern is used in various sections of the code but here is an example that creates the ComputerScienceDepartment instance which is the subclass of the Department abstract class.

PlantUML

The pattern is utilized to create instance of the resulting Department instance(s). The main idea is that BostonUniversity is the class that generates the department using their corresponding builders. So in essensce, the BostonUniversity class also acts as the build director.

PlantUML

A variation of this pattern abstracts how the students and observers sends notification. In this particular implementation, the Department act as a bridge so the FacultyMessenger implementation is abstracted from the rest of the application and can be swapped out with a different implementation without disturbing the rest of the code.

PlantUML

This is utilized on the way concentrations/subconcentrations/course are managed to implement the format() method to generate an HTML that lists all concentrations, sub-concentrations, course and the corresponding syllabus. This leveraging the use of Java generics.

PlantUML

The observer is used here in a way that instead of having the class as the Subject, we instead have the entire Registrar as the Subject. We also don't have the individual students and faculty as observers; instead we have the DepartmentMailRoom as the observer. With this approach we have message query and notification use the same classes. This is also more efficient as there is only one subject/observer.

PlantUML

The pattern is used for computing GPA, allowing more than one approach for computing GPA whether curved or not, although only one strategy is implemented here (non-curved).

PlantUML

• A member of the faculty cannot be a student. In other words, a student named "John Doe" is treated as separate entity as faculty member "John Doe" even though realistically they can be referring to the same person.
• A student takes courses in consecutive school years (no gap).

• Objects/classes are subclassed from AbstractEntity or AbstractEntityRelationship which implements a getId() method. Since there is a lot of lookup in collections, this basic abstract classes overrides Object::equals to ensure value equality through their getId().
• Application relies on java.util.logging package to emit messages on the console.