Homework #2: Doubly-Linked List Solution

Important




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 an 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.



Doubly-Linked List




You are to code a doubly-linked list with a head and tail reference. A linked list is a collection of nodes, each having a data item and a reference pointing to the next node (and, in the case of this assignment, a reference to the previous node). The next reference for the last node in this list and the previous reference for the rst node in this list would be null. Do not use a phantom node to represent the start or end of your list. A phantom or sentinel node is a node that does not store data held by the list and is used solely to indicate the start or end of a linked list. If your list contains n elements, then it should contain exactly n nodes.




Your linked list implementation will implement the LinkedListInterface provided. It will use the default constructor (the one with no parameter) which is automatically provided by Java. Do not write your own constructor.




Nodes




The linked list consists of nodes. A class LinkedListNode is provided to you. LinkedListNode has ve methods to access and set the next node, access and set the previous node, and to access the data in the node.




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 linked list. In addition, all instances of a speci c value from the list can be removed. When removing from the front, the rst node should be removed and the head reference should be updated. When removing from the







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Homework 2: Doubly-Linked List Due: See T-Square










back, the last node should be removed and the tail reference should be updated. When removing from the middle, the previous node of the removed node should point to the next node of the removed node, and the node following the removed node should point to the previous node of the removed node. Make sure that you set any pointers to the deleted nodes to null. See the interface for more details.




A note on JUnits




We have provided a very basic set of tests for your code, in LinkedListStudentTests.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 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 Carey MacDonald (careyjmac@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 LinkedList<Integer() instead of new LinkedList(). 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







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Homework 2: Doubly-Linked List Due: See T-Square










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.




LinkedListInterface.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.




DoublyLinkedList.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.




LinkedListNode.java



This class represents a single node in the linked list. It encapsulates data, the next reference, and the previous reference. Do not alter this le.




LinkedListStudentTests.java



This is the test class that contains a set of tests covering the basic operations on the DoublyLinkedList 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.




DoublyLinkedList.java






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