Homework 2

Overview

This assignment aims to give you a little more practice taxonomizing types, and implementing those taxonomies using Java’s class system.

You have two tasks in this assignment.

First, you’ll need to create a class hierarchy in Java that depicts a logical categorization of the following types.

• Animal
• Beluga
• Chameleon
• Dog
• GermanShepard
• Mammal
• Orca
• Reptile
• ShibaInu
• Snake
• Whale

Each of these types is represented as a class, each with its own file in the hw2/src/cs342/animals directory. These files and classes currently represent a type hierarchy with Animal at the top, and every other class being a child class of Animal.

Animal
    |- Beluga
    |- Chameleon
    |- Dog
    |- GermanShepard
    |- Mammal
    |- Orca
    |- Reptile
    |- ShibaInu
    |- Snake
    |- Whale

You should first decide what a better organization for these types, and then implement that organization by updating the .java files in hw2/src/cs342/animals. You should have the classes inherit / extend each other so that they implement your class hierarchy.

Second, once you’ve taxonomized these types, you’ll need to describe them, by overriding the methods in the Animal class. You will need to override the following methods in your hierarchy:

• public boolean isWarmBlooded()
• public boolean isLivingUnderWater()
• public boolean isNamedAfterEuropeanCountry()
• public boolean canChangeColor()
• public boolean isBlackAndWhite()

The catch is that you can only implement / override each method once in your solution. In other words, can add a maximum of five new method definitions total to the code in hw2/src/cs342/animals. The goal is to have the class system express the correct answers (for the questions represented by these methods) for each type in the system.

The part that will take some thinking through is “which level of the hierarchy to do the overriding at”. Keep in mind that if you override a method on a parent class, you’re also overriding it for all the children of that class (unless you re-override it on a child class, which is not possible in this assignment).

If you’ve done this correctly, then each of these sets of answers should give you back exactly one type, describing a logical animal.

A testing program is included in your repo. See the below “Resources and Suggestions” section for more information.

Requirements

You are only allowed to edit code in hw2/src/cs342/animals, with the exception of the hw2/src/cs342/animals/Animal.java file, which you cannot change. You also may not make any changes to the hw2/src/Main.java file, the included jar file, or any other file in the repo.

You can only override / implement a maximum of five methods in your code. In other words, if you’ve written public boolean more than five times, your solution is incorrect :)

Resources and Suggestions

There is a test script in your repo, called run. It takes five arguments, each corresponding to one of the five methods you’re allowed to override. You run it as follows:

./run --warmblood {true,false} --underwater {true,false} --euroname {true,false} --changecolor {true,false} --blackandwhite {true,false}

proving the values for each flag (warmblood, underwater, etc.) as desired. The program will then check your type hierarchy and return a list of all the types that match the parameters you provided. A correct solution will return exactly one type for each of the combination of values described in the table in the “Overview” section.

For example, to replicate the first row of the table, you’d use ./run --warmblood true --underwater false --euroname true --changecolor false --blackandwhite false, and your program should output “german shepard”.

You might also find the following links useful, especially if you’re not much into animals:

• Orca
• Beluga
• Shiba Inu
• Alaskan Husky

Grading

This assignment will be worth 10 points. Four points for implementing getting the taxonomy / class hierarchy correct, and one point each for your program generating the correct results for each of the six sets of terms described in the table above.

No late or partial credit will be given. Working with other students, or using resources other than the text book or the above Wikipedia links is forbidden and will be considered academic dishonesty.

Due Date

This assignment is due by 11:59AM on Wednesday, June 21, 2017.