Due:Fri 01/17 at 9:00pm; self-evaluation due Sat 01/18 at 10:00pm
Starter files: code.zip
The primary goal of this assignment is to get you writing Java (again or for the first time). As a secondary goal, completing this assignment will help you ensure that you have a properly configured and working Java development environment and IDE, and that you can use the submission system (to be described elsewhere).
Before you start this assignment, you should make sure that you’ve set up a proper CS 3500 environment. You can view the accompanying video tutorial for more help.
We are using the Java SE Development Kit 11 toolchain (JDK 11). You will need this version or later installed.
You need a good Java IDE. We recommend IntelliJ IDEA, but you may use whatever IDE you like.
We strongly recommend that you install Git if you don’t already have it.
Once you’ve installed JDK 11, Git, and an IDE, you probably need to tell the IDE where to find the JDK and Git. Additionally, you should configure your IDE to set your Java language level to 11—
this is a separate configuration step. We will be taking full advantage of Java 11 in this course. Finally, you also need to configure your IDE with the appropriate style settings: see The style guide below.
Get the code for this homework assignment using the “Starter files” link above.
Take a look at the provided code:
The code from The Essence of Objects appears in
src/cs3500/hw01/publication, with tests in
test/Hw01TypeChecks.javacontains a small class designed to help you detect when your code may not compile against the grading tests. In particular, if including
unmodified, in that directory!— in your project produces compilation errors, then it won’t compile for the course staff either.
This part of the assignment is a continuation of the code written in
The Essence of Objects. In particular, you will write a Java class
Webpage (in package
cs3500.hw01.publication) that implements
Publication interface from lecture, with the same
functionality as web page objects created by the ISL+λ function
new-webpage, as seen in the lecture notes.
Write a class
Webpagethat implements the
Publicationinterface. It must define a public constructor:
public Webpage(String title, String url, String retrieved)
The signature of the constructor, including the order of the arguments, is important to enable automated-test–based grading for functional correctness. Don’t forget to write a good Javadoc comment. See how to cite a webpage in MLA and APA style by looking at the Racket code in The Essence of Objects.
Write a JUnit 4 test class,
WebpageTest, that tests both public methods of
Compared to the version from class this week, there are two changes in the code for this homework:
Durationnow has an additional method,
format(String), along with a Javadoc comment detailing its specification.
AbstractDurationFormatTestcontains two simple test methods for
formatExample2. These serve as examples, and you will need to add several more to have good test coverage. Add tests for
formatonly to this class, or else the autograder will not work properly.
To complete this assignment:
You must write sufficient tests to be confident that your implementation of the
formatmethod is correct. Your tests should exercise every non-trivially distinct possibility.
It is recommended that you write these tests before attempting to implement the
formatmethod as specified below. Doing so will help you clarify how the method is supposed to work.
The autograder for this portion of the homework is slightly tricky, and requires your code to be designed in a particular way. First, your tests must be placed in the
AbstractDurationFormatTestclass, and you must leave unchanged the portion of the file marked "Leave this section alone". Second, do not explicitly use
newin your tests: as we did in class, use the
secmethods to construct examples of
The autograder will run your tests against several new
Durationclasses with deliberately-buggy
formatimplementations, and against one perfectly-correct implementation; to earn full credit on this autograder, you must have sufficient tests to catch all of these bugs. In other words, you will succeed on this homework if you write enough correct tests to comprehensively check the
formatmethod, such that at least one fails on any buggy implementation of it, but all tests pass on the correct implementation. Remember: test failures are good things!
You must implement the
Duration.format(String)method in the appropriate place(s). Your implementation must not use any of the string replacement methods such as
replaceAll. (We strongly suggest that you use iteration and not recursion to process a string.) The Javadoc description of this method is a sufficient specification for this method, but requires careful attention: an overly-hasty reading will probably miss some edge cases.
The autograder will also test your implementation for correctness, regardless of whether you wrote your own test cases.
For this assignment, you will be graded on
whether your code compiles,
whether your code implements the specification (functional correctness),
whether you thoroughly test every method that you write, and
how well you follow the style guide.
Coding style is important. For this class we follow Google’s Java style guide. It’s comprehesive but not very long, so I suggest reading the whole thing and then referring to it as needed.
While it can’t yet take on full responsibility for formatting code—
For Intellij IDEA, download
intellij-java-google-style.xmland save it in the
config/codestyles/subdirectory of your IntelliJ configuration folder. Then from within IntelliJ, go to File > Other Settings > Default Settings..., then in the dialog that pops up, go to Editor / Code Style, and select it in the Scheme dropdown, where it should have appeared as an option. If you’ve already created a project, then you’ll additionally need to set this as the project style, using File > Settings.
For Eclipse, download the
eclipse-java-google-style.xml. Under Window > Preferences, select Java / Code Style / Formatter and import the settings.
Check here for more info.
Your submission should include
any files you had to modify or create in order to implement and test your
Please ensure that your submission is a zip file. This zip file should
test/ folders from your project, and
only those folders. These folders should mimic the folder structure
required for your packages (e.g. for a class inside
src/ folder should contain a
cs3500/ folder, inside which is a
hw01/ inside which is a
duration/ folder). Please do not put
these folders within another folder before submitting, as the grader will not
find your files.
You will submit your homework at https://handins.ccs.neu.edu. We have written a
guide for using the handin server, if you are unfamiliar with it. (To log in
to the handin server, you will need an active CCS account. If you are a
CS major or have taken a CS class before, you should have one already. If you
have forgotten your account name or password, go to
click on the “Forgot Username” or “Forgot Password” links.
Once logged in, you will need to enter some simple profile
information (NUID, name and nickname, mostly), and upload a picture of yourself so we
recognize you. After completing that profile, you’ll be taken to a page like
In this screen:
The navigation bar at the top will take you to this homepage via the Bottlenose icon, to your profile via your nickname, and to a list of your currently enrolled courses. You can also log out.
Arranged by semester, you can see your current courses, and your homeworks and teams within them.
In the homework area, you have links to all currently available homeworks, along with basic information about them. The score bubbles to the right show each of your submissions for that assignment; the green one is the one being graded.
Clicking on a homework link will take you to a page where you can see all your submissions in more detail, as well as create a new submission. Note that for assignments with autograders, it may take a little while for the grade to appear; in the meantime it will appear as “Missing”. Do not panic!