CS 171: Introduction to Computer Science II
Assignment #1: OOP and Shape Representations
Due: Wed Feb 2nd at 11:59 PM EDT on Gradescope (Entry Code: 742YK6)
[Late Submission: See Syllabus for policy details.]
Submission Instructions: This programming assignment should be submitted electronically
on Gradescope. Make sure that all Java files you submit can be compiled and run against Java
Development Kit 11 (or higher). You can submit as many times as you want before the deadline.
Your assignment will be partially autograded on Gradescope once you submit so you will receive
the results as soon as the autograder finishes running.
Goals: This assignment is designed to familiarize you with Object-Oriented Programming (OOP)
concepts using the topic of shapes. You will become more familiar with writing Java classes and im-
plementing instance methods that update or access instance variables. You will also apply method
overloading, method overriding, and class inheritance. These OOP concepts are extremely impor-
tant, practical, and fun to play around with. Enjoy!
!! Important !! Your method headers (i.e., return type, method name, and parameter list) should
match the exact description in the handout and starter code, including the case sensitivity of
any method’s name; otherwise, our Gradescope testing scripts will fail and you risk getting 0 points.
Part 1: Complete these simple Java classes
Your first task is to complete the implementation of the following classes that represent different
shapes, by filling in the missing methods in each class. For some methods you will need to either
complete or define the signature of the method as well. Pay careful attention to the expected name
of the method, the order and type of parameters, and the method’s return type, since an incorrect
method signature will cause our testing code to fail when running against your submission.
Note that the missing methods in the code are marked by a TODO prefix. Make sure to remove
the TODO tags once you’re done coding and testing your implementation. This is common practice
when you are coding a problem in the real world. Complete all missing code in the following classes:
• Class Circle is defined inside Circle.java and is meant to represent a circle shape.
• Class Rectangle is defined inside Rectangle.java and is meant to represent a rectangle shape.
• Class ShapeTester is defined inside ShapeTester.java and is meant to compare different ob-
jects (i.e. instances) of shapes.
Part 2: Implement object inheritance in Java
It is often the case that the classes you write to represent real-world data types will inherit properties
(data and methods) from other classes. In this assignment, your second task is to write a new class
called Cylinder and save it in a file named Cylinder.java. Class Cylinder must extend the class
Circle and satisfy the following requirements:
• The center of the cylinder should have an x coordinate, a y coordinate, and the z coordinate
should be 0. It should also have a radius and a height, which is how tall the cylinder is in
the z direction. All coordinates and dimensions should be of type double. Think carefully
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about which variables you will inherit from class Circle and, therefore, which new ones will
you need to define in class Cylinder.
• There should be two constructors in class Cylinder. The first one takes no arguments and
sets the center of the base at (0.0,0.0,0.0), the radius of the base at 1, and the height at 1.
The second constructor takes as input in the exact following order: the x and y coordinates,
the radius of the cylinder, and the height of the cylinder. Note that z is automatically set to
zero in both constructors.
• Your class should define the methods getHeight (which returns the cylinder height), and
setHeight (which updates the cylinder height).
• Your class should override the getArea method from class Circle to make it return the area
of the Cylinder object instead. Your method implementation here must utilize the getArea
computation already defined in the super class Circle. (You may invoke other methods from
the super class Circle as well, if needed.)
• Your class should define the method getVolume which returns the volume of the Cylinder
object (as a double value). Your method implementation here must utilize the getArea
computation already defined in the super class Circle.
Testing and submitting your work
You can define a main method in each class you complete or write, in order to test the different
methods you have implemented in that class. You should try different test cases and troubleshoot
your code using inputs you know the answers to. Your code will be assessed by a main method that
you do not have access to – the Gradescope autograder only exposes a subset of the test cases that
we will try. Remember that your methods must have signatures (headers) thatmatch exactly the
provided descriptions, otherwise the autograder will not be able to call your methods correctly,
resulting in a zero grade.
The Circle class has the most information filled in, followed by the Rectangle class. The
ShapeTester class only has method descriptions, and it is up to you to write the Cylinder class.
To submit this assignment, you must upload four files on Canvas: Circle.java, Rectangle.java,
ShapeTester.java, and Cylinder.java. Make sure all files compile and run successfully before
you submit them.
Discussion and asking for clarifications: Use our course Piazza page to post questions about
the assignment if you need a clarification about any of the methods. Do not post solutions!
Grading: If a program does not compile, you will get 0 points for it. Programs that do compile
successfully will be executed with different test cases. The breakdown of marks is as follows (detailed
breakdown of the marks is available inside the starter code files):
• Class Circle correctness [20 points]
• Class Rectangle correctness [20 points]
• Class ShapeTester correctness [20 points]
• Class Cylinder correctness [35 points: 8 points for proper class and instance variables decla-
ration, 6 points for constructors, 12 points for getArea, 9 points for remaining methods]
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• Code clarity and style (add meaningful comments when appropriate!) [5 points]
Honor Code: Solve this assignment individually; do not collaborate with classmates or look for
online solutions. We check for code plagiarism. The assignment is governed by the College Honor
Code and Departmental Policy. Remember, any code you submit must be your own; otherwise you
risk being investigated by the Honor Council and facing the consequences of that. Finally, please
remember to have the following comment included at the top of every file:
/*
THIS CODE WAS MY OWN WORK, IT WAS WRITTEN WITHOUT CONSULTING
CODE WRITTEN BY OTHER STUDENTS OR COPIED FROM ONLINE RESOURCES. _Your_Name_Here_
*/
Submission Checklist: We’ve created this checklist to help you make sure you don’t miss
anything important. Note that completing all these items does not guarantee full points, but at
least assures you are unlikely to get a zero.
□ Did your four files (i.e., Circle.java, Rectangle.java, ShapeTester.java, Cylinder.java) compile
on the command line using JDK 11 or above (e.g. JDK 17)?
□ Did your submission on Gradescope successfully compile and pass at least one autograder
test case?
□ Have you included the honor code on top of every file?
□ Did you remove the TODO prefix from the methods you needed to implement?
□ Did you give your variables meaningful names (i.e., no foo or bar variables)?
□ Did you add meaningful comments to the code when appropriate?
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