Homework 1: ArrayList
There are general homework guidelines you must always follow. If you fail to follow any of the following
guidelines you risk receiving a 0 for the entire assignment.
1. All submitted code must compile under JDK 8. This includes unused code, so don’t submit extra
files that don’t compile. Any compile errors will result in a 0.
2. Do not include any package declarations in your classes.
3. Do not change any existing class headers, constructors, instance/global variables, or method signatures.
4. Do not add additional public methods.
5. Do not use anything that would trivialize the assignment. (e.g. don’t import/use java.util.ArrayList
for an Array List assignment. Ask if you are unsure.)
6. Always be very conscious of efficiency. Even if your method is to be O(n), traversing the structure
multiple times is considered inefficient unless that is absolutely required (and that case is extremely
7. You must submit your source code, the .java files, not the compiled .class files.
8. After you submit your files, redownload them and run them to make sure they are what you
intended to submit. You are responsible if you submit the wrong files.
You are to code an Array List. An Array List is a list data structure backed by an array where all of
the data is contiguous and aligned with index 0 of the array.
Your array list must follow the requirements stated in the javadocs of each method you must implement.
A constructor stub is provided for you to fill out. Do not change the constructor provided or implement
a different one.
You will implement three add() methods. One will add to the front, one will add to the back, and one
will add anywhere in the list. When adding to the front or the middle of the list, subsequent elements
must be shifted back one position to make room for the new data. See the javadocs for more details.
Removing, just like adding, can be done from the front, the back, or anywhere in your ArrayList. When
removing from the front or from the middle of the list, the element should be removed and all subsequent
elements should be shifted forward by one position. When removing from the back, the last element
should be set to null in the array. All unused positions in the backing array must be set to
null. See the javadocs for more details.
The starting capacity of your ArrayList should be the constant INITIAL CAPACITY defined in ArrayList.java.
Reference the constant as-is. Do not simply copy the value of the constant. If, while adding an element,
the ArrayList does not have enough space, you should regrow the backing array to twice its old capacity.
Do not regrow the backing array when removing elements.
Homework 1: ArrayList Due: See Canvas
Differences between Java API and This Assignment
Some of the methods in this assignment are called different things in Java’s List class. This won’t matter
until you tackle coding questions on the first exam, but it’s something to be aware of. The list below
shows all methods with a different name and their Java API equivalent. The format is assignment method
name ⇒ Java API name.
• addAtIndex(int index, T data) ⇒ add(int index, T data)
• addToFront(T data) ⇒ addFirst(T data)
• addToBack(T data) ⇒ addLast(T data)
• removeAtIndex(int index) ⇒ remove(int index)
• removeFromFront() ⇒ removeFirst()
• removeFromBack() ⇒ removeLast()
Here is the grading breakdown for the assignment. There are various deductions not listed that are
incurred when breaking the rules listed in this PDF, and in other various circumstances.
Keep in mind that add functions are necessary to test other functions, so if an add doesn’t work, remove
tests might fail as the items to be removed were not added correctly. Additionally, the size function is
used many times throughout the tests, so if the size isn’t updated correctly or the method itself doesn’t
work, many tests can fail.
A note on JUnits
We have provided a very basic set of tests for your code, in ArrayListStudentTests.java. These
tests do not guarantee the correctness of your code (by any measure), nor does it guarantee you any
grade. You may additionally post your own set of tests for others to use on the Georgia Tech GitHub as
a gist. Do NOT post your tests on the public GitHub. There will be a link to the Georgia Tech GitHub
as well as a list of JUnits other students have posted on the class Piazza.
If you need help on running JUnits, there is a guide, available on Canvas under Files, to help you
run JUnits on the command line or in IntelliJ.
Homework 1: ArrayList Due: See Canvas
Style and Formatting
It is important that your code is not only functional but is also written clearly and with good style. We
will be checking your code against a style checker that we are providing. It is located on Canvas, under
Files, along with instructions on how to use it. We will take off a point for every style error that occurs.
If you feel like what you wrote is in accordance with good style but still sets off the style checker please
email Tim Aveni ([email protected]) with the subject header of “[CS 1332] CheckStyle XML”.
Javadoc any helper methods you create in a style similar to the existing Javadocs. If a method is
overridden or implemented from a superclass or an interface, you may use @Override instead of writing
Javadocs. Any Javadocs you write must be useful and describe the contract, parameters, and return
value of the method; random or useless javadocs added only to appease Checkstyle will lose points.
Any submission that contains profanity, vulgar, or obscene language will receive an automatic zero on
the assignment. This policy applies not only to comments/javadocs but also things like variable names.
When throwing exceptions, you must include a message by passing in a String as a parameter. The message must be useful and tell the user what went wrong. “Error”, “BAD THING HAPPENED”,
and “fail” are not good messages. The name of the exception itself is not a good message.
Bad: throw new IndexOutOfBoundsException(“Index is out of bounds.”);
Good: throw new IllegalArgumentException(“Cannot insert null data into data structure.”);
If available, use the generic type of the class; do not use the raw type of the class. For example, use new
LinkedList<Integer() instead of new LinkedList(). Using the raw type of the class will result in a
You may not use these in your code at any time in CS 1332.
• Arrays class
• Array class
• Thread class
Homework 1: ArrayList Due: See Canvas
• Collections class
• Reflection APIs
• Inner or nested classes
• Lambda Expressions
• Method References
If you’re not sure on whether you can use something, and it’s not mentioned here or anywhere else in
the homework files, just ask.
Debug print statements are fine, but nothing should be printed when we run your code. We expect
clean runs – printing to the console when we’re grading will result in a penalty. If you submit these, we
will take off points.
The following file(s) have been provided to you. There are several, but you will only edit one of them.
This is the class in which you will implement the ArrayList. Feel free to add private helper methods
but do not add any new public methods, inner/nested classes, instance variables, or
This is the test class that contains a set of tests covering the basic operations on the ArrayList
class. It is not intended to be exhaustive and does not guarantee any type of grade. Write your
own tests to ensure you cover all edge cases.
You must submit all of the following file(s). Please make sure the filename matches the filename(s)
below, and that only the following file(s) are present. If you make resubmit, make sure only one copy of
the file is present in the submission.
After submitting, double check to make sure it has been submitted on Canvas and then download your
uploaded files to a new folder, copy over the support files, recompile, and run. It is your responsibility
to re-test your submission and discover editing oddities, upload issues, etc.