W1D4 Readings & Questions

gistfile1.txt

Q1: What is an instance variable?
- instance variable is a variable that is owned by an instantiated object.

Q2: The 4 Pillars of Object Oriented Programming are Abstraction, Encapsulation, Inheritance and Polymorphism. Describe each one.
Abstraction - to "hide" the logic and control what can be accessed or called by other objects
Encapsulation - to combine related objects, data and operations into a single unit
Inheritance - enable objects to receive/inherit the properties/attributes and methods without requiring it to re-declare or re-implement it
Polymorphism - allows the properties and methods of subclasses to have a different behavoir.

Q3:

a) As my next business venture, I want to open a bicycle rental shop, and I want an app to help me organize it. The app will need to keep a list of all bicycles in inventory. At any given time, a bicycle may be in one of 3 states: waiting for maintenance, ready to rent, or rented.

I have a few mechanics, each of whom can only fix 1 bike at a time. Each time the mechanic finishes with one bike, it becomes ready to rent, and each time a customer returns a bike, it needs to be checked for maintenance. When a mechanic is done fixing a bike, he must be assigned another one waiting for maintenance.

If you were to write an app for my shop, how would you design your object model?
Clas Shop
- properties: bikeBeingFixed (Bike class), bikesForRent(Array of Bike), bikesToBeChecked(Array of Bike), mechanics(Array of Mechanic)
- methods: getNextBikeForRent, getNextBikeToBeCheck, addBikeForRent, addBikeToBeCheck
Class Bike
- properties: states
Class Mechanic
- properties: bikeCurrentlyFixing
- method: startFixingBike, justFinishedFixingBike

b) Now, assume my mechanics take 1 hour to fix each bike. But to keep business moving, I also want to hire junior mechanics, each of whom can fix a bike every two hours. How does this change your object model?
Class Mechanic
- properties: bikeCurrentlyFixing **ADD seniority and timeToFinishFixing
- method: startFixingBike, justFinishedFixingBike