Description
Style and Formatting It is important that your code is not only functional, but written clearly and with good programming style. Your code will be checked against a style checker. The style checker is provided to you, and is 1 Homework 1: SinglyLinkedList Due: See Canvas located on Canvas. It can be found under Files, along with instructions on how to use it. A point is deducted for every style error that occurs. If there is a discrepancy between what you wrote in accordance with good style and the style checker, then address your concerns with the Head TA. Javadocs Javadoc any helper methods you create in a style similar to the existing 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. Vulgar/Obscene Language 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. Exceptions 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. For example: Bad: throw new IndexOutOfBoundsException(‘‘Index is out of bounds.’’); Good: throw new IllegalArgumentException(‘‘Cannot insert null data into data structure.’’); In addition, you may not use try catch blocks to catch an exception unless you catching an exception you have explicitly thrown yourself with the throw new ExceptionName(‘‘Exception Message’’); syntax (replacing ExceptionName and Exception Message with the actual exception name and message respectively). Generics If available, use the generic type of the class; do not use the raw type of the class. For example, use new LinkedList() 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. • package • System.arraycopy() • clone() • assert() • Arrays class • Array class • Thread class • Collections class • Collection.toArray() • Reflection APIs 2 Homework 1: SinglyLinkedList Due: See Canvas • Inner or nested classes • Lambda Expressions • Method References (using the :: operator to obtain a reference to a method) 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. JUnits We have provided a very basic set of tests for your code. These tests do not guarantee the correctness of your code (by any measure), nor do they 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. 3 Homework 1: SinglyLinkedList Due: See Canvas SinglyLinkedList You are to code a SinglyLinkedList with head and tail references. A linked list is a collection of nodes, each having a data item and references to other nodes. In a SinglyLinkedList, each node has a reference to the next node. Since it is non-circular, the next reference for the tail is 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. The SinglyLinkedList must follow the requirements stated in the javadocs of each method you must implement. Your linked list implementation will use the default constructor (the one with no parameters) which is automatically provided by Java. Do not write your own constructor. Nodes The linked list consists of nodes. A class SinglyLinkedListNode is provided to you. This class has getter and setter methods to access and mutate the structure of the nodes. Adding You will implement three add() methods. One will add to the front, one will add to the back, and one will add to anywhere in the list given a specific index. See the javadocs for more details. Removing You will also implement three remove() methods – from the front, the back, or anywhere in the list given a specific index. Make sure that there is no longer any way to access the removed node so that the node will be garbage collected. See the javadocs for more details. Garbage Collection Java will automatically mark objects for garbage collection based on whether there is any means of accessing the object. In other words, if we want to remove a node from the list, we must remove all references to that node. What the next reference of that node points to doesn’t particularly matter. As long as no references can reach the node, the node will be garbage collected eventually. Equality There are two ways of defining objects as equal: reference equality and value equality. Reference equality is used when using the == operator. If two objects are equal by reference equality, that means that they have the exact same memory locations. For example, say we have a Person object with a name and id field. If you’re using reference equality, two Person objects won’t be considered equal unless they have the exact same memory location (are the exact same object), even if they have the same name and id. Value equality is used when using the .equals() method. Here, the definition of equality is custom made for the object. For example, in that Person example above, we may want two objects to be considered equal if they have the same name and id. Keep in mind which makes more sense to use while you are coding. You will want to use value equality in most cases in this course when comparing objects. Notable cases where you’d use reference equality include checking for null or comparing primitives (in this case, it’s just the == operator being overloaded). 4 Homework 1: SinglyLinkedList Due: See Canvas Differences between Java API and This Assignment Some of the methods in this assignment are called different things or don’t exist in Java’s LinkedList class. Additionally, Java’s built in LinkedList is a Doubly-Linked List, so the efficiency of some operations will differ. 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 if it exists. 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) ⇒ add(T data) or addLast(T data) • removeAtIndex(int index) ⇒ remove(int index) • removeFromFront() ⇒ poll() or pollFirst() • removeFromBack() ⇒ pollLast() 5 Homework 1: SinglyLinkedList Due: See Canvas Grading 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. Methods: addAtIndex 10pts addToFront 5pts addToBack 5pts removeAtIndex 10pts removeFromFront 5pts removeFromBack 5pts get 10pts isEmpty 4pts clear 5pts removeLastOccurrence 10pts toArray 6pts Other: Checkstyle 10pts Efficiency 15pts Total: 100pts Provided The following file(s) have been provided to you. There are several, but we’ve noted the ones to edit. 1. SinglyLinkedList.java This is the class in which you will implement the SinglyLinkedList. Feel free to add private helper methods but do not add any new public methods, inner/nested classes, instance variables, or static variables. 2. SinglyLinkedListNode.java This class represents a single node in the linked list. It encapsulates the data and the next reference. Do not alter this file. 3. SinglyLinkedListStudentTest.java This is the test class that contains a set of tests covering the basic operations on the SinglyLinkedList 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 file(s). Make sure all file(s) listed below are in each submission, as only the last submission will be graded. Make sure the filename(s) matches the filename(s) below, and that only the following file(s) are present. Do NOT submit SinglyLinkedListNode.java for this homework; if you do, your homework will not compile on Gradescope. If you resubmit, be sure only one copy of each file is present in the submission. If there are multiple files, do not zip up the files before submitting; submit them all as separate files. Once submitted, double check that it has uploaded properly on Gradescope. To do this, download 6 Homework 1: SinglyLinkedList Due: See Canvas your uploaded file(s) to a new folder, copy over the support file(s), recompile, and run. It is your sole responsibility to re-test your submission and discover editing oddities, upload issues, etc. 1. SinglyLinkedList.java 7