@version 14.4.2 in the interface javadoc.In this assignment, you’ll practice
The 2018 Winter Olympics have come and gone! Unsatisfied with their 4th place finish, Team USA has hired you, a young, ambitious Georgia Tech CS grad, to revamp their system for managing their athletes! You’ve decided to utilize your vast knowledge of Java collections and use a custom ArrayList implementation.
Up to this point in the course, we’ve used arrays as our primary data structure. It’s time to learn about another one, ArrayLists!
Our main gripe with arrays is that they are fixed size. ArrayLists solve that problem – they resize as elements are added to them. Behind the scenes, an ArrayList stores the elements added to it in a backing array. You’ll similarly use an array in your implementation of AthleteList as your backing data structure. If the array is at capacity and an element needs to be added, then the contents of the backing array are copied into a new, larger array. This new array becomes the backing array.
Something else to be noted in our discussion of ArrayLists is the distinction we make between capacity and size. Capacity is the maximum number of elements the backing array can hold. This is an implementation detail that’s hidden from the user. Size is the number of elements that have been added to an ArrayList, and is known to the user through a size() method. Size is typically tracked by the ArrayList. You’ll encounter both of these terms in your implementation.
You will be provided the following files. You may only modify train() in Athlete!
The file names are clickable, and take you to the Java files.
AthleteListInterface (download) – your AthleteList class will need to implement this interface. All details regarding the abstract methods you will override has been provided in the Javadocs, and have been repeated below for convenience. AthleteListInterface contains the following abstract methods:
void add(T t) – This method adds a <T extends Athlete> object to the AthleteList . If the AthleteList is full, you’ll need to resize it to twice the current capacity prior to adding the element. If the element passed in is null, throw an IllegalArgumentException .
T remove(int index) – Removes the Athlete at the passed-in index and returns it. You should shift every element to the right of the removed element one spot to the left, so that there are no gaps in the middle of the AthleteList . See the interface for an example. If index is less than zero or greater than or equal to the number of elements remaining in the AthleteList , you should throw an IndexOutOfBoundsException .
T get(int index) – Returns the element at the specified index. If index is less than zero or greater than or equal to the number of elements remaining in the AthleteList , you should throw an IndexOutOfBoundsException .
void clear() – Empties the AthleteList of all elements and resets the backing array back to its original capacity.
int size() – Returns the number of elements currently in the AthleteList.
boolean isEmpty() – Returns whether the AthleteList is empty or not.
void train(int index) – Calls the train() method of the Athlete at the passed-in index. More details on that below. As with get and remove, if index is out of bounds, throw an IndexOutOfBoundsException .
void rest(int index) – Calls the rest() method of the Athlete at the passed-in index. If
index is out of bounds, throw an IndexOutOfBoundsException .
T[] asArray() – This method is for our grading (and your testing!) purposes. Return an array with the same elements as the backing array, but with size() elements, that is, no null elements from right-padding a backing array that is bigger than the number of elements currently stored in the AthleteList.
Athlete (download) – A class used to model an athlete. An Athlete has the following instance variables and instance methods:
name – A String representing the name of the Athlete.
energy – An int representing the amount of energy the Athlete has left. This depletes as the Athlete trains.
strength – An int representing the strength of the Athlete. This increases as the Athlete trains.
public Athlete(String name, int energy, int strength) – Public constructor with parameters for each of the instance variables.
public Athlete(String name) – Public constructor that only takes a String for the name and sets energy to 15 and strength to 5.
Getters for each of the instance variables.
public void train() – Decreases energy by the current value of strength, and then increases strength by one. You will modify this method as such: If energy is less than strength, throw an OvertrainedAthleteException, which you will write.
public void rest() – Increases energy by 5.
You will need to write the following classes:
AthleteList – your Athlete management solution. This class will implement AthleteListInterface, and should be of any generic type which is an Athlete or a subclass of Athlete. Use an array as your backing data structure. Write one no-arg constructor, which initializes the backing array. When you initialize an AthleteList , use the INITIAL_CAPACITY constant defined in AthleteListInterface . I recommend you keep track of the number of elements currently in the AthleteList.
OvertrainedAthleteException – A custom unchecked exception which will be thrown when a tired Athlete’s train() is called. The constructor for OvertrainedAthleteException should
accept a String as a parameter and invoke the constructor in the super class that also accepts a String as a parameter. This parameter is the message that will be displayed when an OvertrainedAthleteException is thrown. You will also need to modify the train() method in Athlete as described above.
ArrayList).java.util.Arrays class nor System.arrayCopy for this homework! Doing so
will be considered oversimplifying the assignment and you will lose most, if not all, points.AthleteListInterface carefully! There’s a lot to digest in this homework, make you understand what’s expected of each method.asArray() will be very useful in debugging!AthleteList constructoradd() correctly adds an element to AthleteListadd() correctly resizes the backing array when necessaryremove() correctly removes an element from AthleteListremove() correctly shifts elements after removalget()clear()size()isEmpty()AthleteList’s train()AthleteList’s rest()asArray()OvertrainedAthleteExceptionAthlete’s train() correctly throws OvertrainedAthleteExceptionFor each of your homwork assignments we will run checkstyle and deduct one point for every checkstyle error.
For this homework there is no checkstyle cap, meaning you can lose all points on this assignment due to style errors.
java -jar checkstyle-6.2.2.jar *.java.java -jar checkstyle-6.2.2.jar -j *.java.When completing homeworks for CS1331 you may talk with other students about:
OKAY: “Hey, I’m really confused on how we are supposed to implement this part of the homework. What strategies/resources did you use to solve it?”
BY NO MEANS OKAY: “Hey… the homework is due in like 20 minutes… Can I see your code? I promise won’t copy it directly!”
In addition to the above rules, note that it is not allowed to upload your code to any sort of public repository. This could be considered an Honor Code violation, even if it is after the homework is due.
Athlete.java and your AthleteList.java and OvertrainedAthleteException.java files to Canvas.Practice safe submission! Verify that your HW files were truly submitted correctly, the upload was successful, and that your program runs with no syntax or runtime errors. It is solely your responsibility to turn in your homework and practice this safe submission safeguard.
This procedure helps guard against a few things: