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Week 05: Introduction to OOP

Thinking in objects, derived getters, cohesion & coupling, JUnit testing, static members, and has-a relationships in a card game

Module 1 - Introduction to Objects

Thinking in Objects

Find the nouns — turn real-world domains into class candidates

KNOW vs DO Responsibilities

Every object is brain (data it knows) or muscle (actions it performs) — or both

Module 2 - Classes (New Pieces)

Derived Getters

A getter doesn't have to read a field — it can calculate the value

Boolean Getters: is… / has…

Why isAdult() reads better than getAdult() — the Java convention

Default Access Modifier

No keyword = package-private — what that actually means and when you'd hit it

How related are the parts inside a class — aim for high cohesion (coupling comes later in Module 5)

Module 3 - Unit Testing

The Testing Pyramid

Unit, integration, end-to-end — how many of each, and what each one tests

JUnit Setup in IntelliJ

Generate → Test → Fix dependency → run — mock IntelliJ walkthrough

Arrange / Act / Assert Anatomy

The three sections of a clean unit test — using the Roy Osherove naming pattern

JUnit Assertions Picker

assertEquals, assertTrue, assertFalse, assertArrayEquals — pick the right one

Module 4 - Static Methods & Variables

Instance vs Static Members

Per-object vs shared — one interestRate for all BankAccounts

Static Classes (the Math pattern)

Private constructor, only static methods — a library you don't instantiate

Module 5 - Class Interactions

Has-A Relationship & Coupling

Hand has-a Card, Deck has-a Card — plus loose vs tight coupling between classes

Class Communication Walkthrough

How main orchestrates the game without doing the work itself

Quick Reference Guides

Week 5 Cheat Sheet

Quick reference for OOP concepts, derived getters, JUnit, static, and has-a relationships

Glossary / Key Terms

All Week 5 vocabulary — cohesion, coupling, derived getter, has-a, @Test, AAA, static and more

Common Errors Guide

JUnit gotchas, static misuse, wrong assertion choice, has-a confusion

JUnit Reference

Assertions table, AAA template, naming conventions — copy-ready snippets

Exercise companions help you understand each exercise — what to build, what a successful run looks like, and which concepts you need. No solutions, no spoilers.

Workbook 4a - Module 1: Thinking in Objects (paper)

Brainstorm the objects a hotel app would need — find the nouns in the scenarios

Hotel Responsibilities

Assign each KNOW and DO responsibility to exactly one object — refine your list

Workbook 4a - Module 2: hotel-operations

hotel-operations: Create Classes

Build Room, Reservation, and Employee classes with backing variables, constructors, and getters

hotel-operations 2: Add Methods

checkIn / checkout / cleanRoom on Room; punchIn / punchOut on Employee

hotel-operations 3: Overload Methods

No-arg punchIn / punchOut using LocalDateTime, plus a Hotel class with bookRoom and overloaded constructors

Workbook 4a - Module 3: Unit Tests

hotel-operations Unit Tests

Write RoomTest and EmployeeTest — pick scenarios, name tests by the 3-part pattern

Workbook 4a - Module 4: Static

NameFormatter (Static Class)

Build a static utility class — private constructor, three overloaded format methods

Workbook 4a - Module 5: Class Interactions

Use Card, Hand, and Deck to deal a real game — declare a winner closest to 21

Workshop 4w

Week 5 workshop — multi-class architecture: Vehicle, Dealership, FileManager, UserInterface, Program

Practice what you learned with interactive games — test your knowledge, race the clock, and have fun.

Thinking in Objects

Know-vs-Do Sorter

Drag each responsibility into KNOW (data) or DO (action)

Classes & Getters

Derived or Stored?

Given a getter, decide whether it should read a field or calculate the answer

Unit Testing

Pyramid Climber

Match each test scenario to its layer — unit, integration, or end-to-end

Drag the lines of a unit test into Arrange, Act, and Assert

Pick the Assertion

Read the scenario, choose the right JUnit assertion method

Static

Static or Instance?

Given a member, decide whether it should be static or per-instance — and why

Class Interactions

Read a description, identify which classes have-a relationship with which

Mixed Review

Find the bug and pick the fix — Week 5 edition covering OOP, JUnit, static, has-a

Flashcard Quiz 4

Test your Week 5 vocabulary — OOP, testing, static, class relationships

Capstone

A multi-round game-night challenge using everything you learned about OOP, has-a relationships, and testing