Homework 1: Array List Solution

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.







All submitted code must compile under JDK 8. This includes unused code, so don't submit extra les that don't compile. Any compile errors will result in a 0.



Do not include any package declarations in your classes.



Do not change any existing class headers, constructors, or method signatures.



Do not add additional public methods.



Do not use anything that would trivialize the assignment. (e.g. don't import/use java.util.ArrayList for a Array List assignment. Ask if you are unsure.)



Always be very conscious of e ciency. Even if your method is to be O(n), traversing the structure multiple times is considered ine cient unless that is absolutely required (and that case is extremely rare).



You must submit your source code, the .java les, not the compiled .class les.



After you submit your les, redownload them and run them to make sure they are what you intended to submit. You are responsible if you submit the wrong les.






Array List




You are to code an Array List. An Array List is a list data structure backed by an array.




Your array list implementation will implement the ArrayListInterface provided. A constructor stub is provided. You must add any necessary statements to this constructor. Do not change the constructor provided or implement a di erent one.




Adding




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. See the interface for more details.




Removing




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 interface for more details.




Capacity




The starting capacity of your ArrayList should be the constant INITIAL CAPACITY de ned in ArrayListInterface. 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.












Grading




Here is the grading breakdown for the assignment:




Methods:






addAtIndex
11pts




addToFront
7pts




addToBack
7pts




removeAtIndex
8pts




removeFromFront
6pts




removeFromBack
4pts




get
10pts




clear
5pts




isEmpty
5pts




Regrowing
12pts




Other:






Checkstyle
10pts




E ciency
15pts




Total:
100pts







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 (when it comes up).




If you need help on running JUnits, there is a guide, available on T-Square under Resources, to help you run JUnits on the command line or in IntelliJ.




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 in T-Square, under Resources, along with instructions on how to use it. We will take o a point for every style error that occurs. If you feel like what you wrote is in accordance with good style but still sets o the style checker please email Raymond Ortiz (rortiz9@gatech.edu) with the subject header of \CheckStyle XML".




Javadocs




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.





Exceptions




When throwing exceptions, you must include a message by passing in a String as a parameter. The mes-sage 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.




For example:




throw new PDFReadException("Did not read PDF, will lose points.");




throw new IllegalArgumentException("Cannot insert null data into data structure.");




Generics



If available, use the generic type of the class; do not use the raw type of the class. For example, use new ArrayList<Integer() instead of new ArrayList(). Using the raw type of the class will result in a penalty.




Forbidden Statements




You may not use these in your code at any time in CS 1332.




break may only be used in switch-case statements




continue package




System.arraycopy() clone()




assert()




Arrays class Array class




Collections class




Collection.toArray()




Re ection APIs




Inner or nested classes




Debug print statements are ne, 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 o points.




Provided




The following le(s) have been provided to you. There are several, but you will only edit one of them.




ArrayListInterface.java



This is the interface you will implement. All instructions for what the methods should do are in the javadocs. Do not alter this le.






ArrayList.java



This is the class in which you will implement the interface. Feel free to add private helper methods but do not add any new public methods, inner/nested classes, instance variables, or static variables.




ArrayListStudentTests.java



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.







Deliverables




You must submit all of the following le(s). Please make sure the lename matches the lename(s) below. Be sure you receive the con rmation email from T-Square, and then download your uploaded les to a new folder, copy over the interfaces, recompile, and run. It is your responsibility to re-test your submission and discover editing oddities, upload issues, etc.




ArrayList.java