Class Interaction Lab

Lab Objectives

• Reinforce Creating Classes that have a collection of Objects
• Practice using object methods within other class methods.

Practice

To re-inforce the concept of object interaction, and classes including references to other classes, let’s build on the Library exercise from todays warmup.

In small groups, create a new Console app called DenverLibrary. In this project, create the following classes:

A Book should have two properties that are set on instantiation: string Title, and string Author. Other than a constructor, Book does not need any methods.

A Branch represents a location in the library system, like “Central Library”, or “John “Thunderbird Man” Emhoolah, Jr. Branch Library”. A branch should have one property that is set on instantiation: string Name. The branch constructor should also create an empty List<Book> assigned to the Property Books. In addition to these to properties, a Branch should be able to add a book to it’s Books, and provide a List<string> of all authors represented at that branch.

A Library represents a city-wide library, like “Denver Public Library”. A library should have one property that is set on instantiation: string Name. The library constructor should also create an empty List<Branch> assigned to the Property Branches. In addition to these to properties, a Library should be able to add a branch to it’s Branches. A Library should also be able to provide a List<string> of the names of all it’s branches, as well as a List<string> of the titles of all of the books contained within all of its branches.

When complete, the following code should be able to be run in Program.cs.

using DenverLibrary;

var hungerGames = new Book("The Hunger Games", "Suzanne Collins");
var catchingFire = new Book("Catching Fire", "Suzanne Collins");
var mockingjay = new Book("Mockingjay", "Suzanne Collins");
var faultyStars = new Book("The Fault In Our Stars", "John Green");
var mockingbird = new Book("To Kill a Mockingbird", "Harper Lee");

var centralLibrary = new Branch("Central Library");
centralLibrary.AddBook(mockingbird);
centralLibrary.AddBook(mockingjay);

var thunderbirdMan = new Branch("John \"Thunderbird Man\" Emhoolah, Jr. Branch Library");
thunderbirdMan.AddBook(faultyStars);
thunderbirdMan.AddBook(catchingFire);
thunderbirdMan.AddBook(hungerGames);

List<string> centralAuthors = centralLibrary.AllAuthors();
// { "Harper Lee", "Suzanne Collins" }

List<string> thunderbirdAuthors = thunderbirdMan.AllAuthors();
// { "John Green", "Suzanne Collins", "Suzanne Collins" }
// Note: it is possible to return a list of *unique* authors, but you do not have to focus on that particular problem now :) 

var denverPublicLibrary = new Library("Denver Public Library");
denverPublicLibrary.AddBranch(centralLibrary);
denverPublicLibrary.AddBranch(thunderbirdMan);

List<string> branchNames = denverPublicLibrary.BranchNames();
// { "Central Library", "John \"Thunderbird Man\" Emhoolah, Jr. Branch Library" }

List<string> allBooksTitles = denverPublicLibrary.AllBooks();
// { "To Kill a Mockingbird", "Mockingjay", "The Fault In Our Stars", "Catching Fire",  "The Hunger Games" }

Keep an Eye on Slack! We will be coming back together a few times to answer questions and any common issues that are coming up.