Lab-ArrayQueue/ArrayQueue.java at master · taioyui/Lab-ArrayQueue · GitHub

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packageorg.cct;

importjava.util.NoSuchElementException;

/**
 * A Queue is a data structure that stores data (integers here) according to a set of rules.
 * Specifically each element added to the queue gets added to the end (tail) of the Queue, and every
 * element removed from the Queue is taken from the front of the queue (head).
 *
 * @author Jenny
 * @version 0.0.1
 */
publicclassArrayQueue {

intsize = 0; // current number of elements in the Queue
int[] arrayQueue; // data structure to hold the elements
intmaxCapacity; // maximum capacity of the queue
inthead; // pointer to the front of the Queue
inttail; // pointer to the end of the Queue

/**
 * Default constructor to set default capacity to 10
 */
publicArrayQueue() {
maxCapacity = 10;
arrayQueue = newint[maxCapacity];
//Fix 3: We are not moving head anymore so it`s always 0
head = 0;
tail = -1;
size = 0;
 }

/**
 * Bespoke constructor that allows the client to set the maximum capacity
 *
 * @param maxCapacity capacity of the array holding the data
 */
publicArrayQueue(intmaxCapacity) {
this.maxCapacity = maxCapacity;
arrayQueue = newint[maxCapacity];
//Fix 3: We are not moving head anymore so it`s always 0
head = 0;
tail = -1;
size = 0;
 }

/**
 * Is the Queue empty or not
 *
 * @return whether the Queue is empty or not
 */
publicbooleanisEmpty() {
returnsize == 0;
 }

/**
 * Add data to the end of the queue
 *
 * @param data Data to be added
 * @throws IndexOutOfBoundsException cannot add to a full queue (reached end of queue)
 */
publicvoidenqueue(intdata) throwsIndexOutOfBoundsException {
if (isFull()) {
thrownewIndexOutOfBoundsException("Out of bounds");
 }
arrayQueue[++tail] = data;
size++;
 }

/**
 * Remove data from the front of the queue
 *
 * @return the data from the front of the queue
 * @throws NoSuchElementException Cannot remove data from an empty queue
 */
publicintdequeue() throwsNoSuchElementException {
if (size == 0) {
thrownewNoSuchElementException();
 }
intresult = arrayQueue[head];
//Fix 2: Take head element from the queue and shift elements towards head
System.arraycopy(arrayQueue, 1, arrayQueue, 0, size);

size--;
returnresult;
 }

/**
 * Determine if the Queue is full or not
 *
 * @return whether the Queue is full or not
 */
publicbooleanisFull() {
//Fix 1: size should equals maxCapacity
returnsize == maxCapacity;
 }

/**
 * Look at the data at the front of the queue, do not remove it.
 *
 * @return the data at the front of the queue
 * @throws NoSuchElementException We cannot peek at elements in an empty queue
 */
publicintpeek() throwsNoSuchElementException {
if (size == 0) {
thrownewNoSuchElementException();
 }
//Fix 4: As head is always 0 we should not increment head
returnarrayQueue[head];
 }

publicintsize() {
returnsize;
 }


}