Can someone help me with this question?

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package dsassignment3;

import DataStructures.EmptyCollectionException;

import DataStructures.InvalidArgumentException;

import DataStructures.LinearNode;

import java.util.ArrayList;

/**

*

* @author author

* @version Fall 2019

* @param

*/

public class WorkAheadQueue implements WorkAheadQueueADT

{

protected LinearNode front;

protected LinearNode back;

protected ArrayList> frontThreeNodes;

protected ArrayList frontThreeElements;

protected int numNodes = 0;

/**

* Default Constructor

*/

public WorkAheadQueue() {

numNodes = 0;

front = null;

back = null;

}

/**

* Removes and returns the element that is at place x in the queue.

* Precondition: x must be less than 5, x must be less than size

* Note: indexing from 0: 0 == front element, 1 == second element, etc.

*

* @param x the passed in index of the element to be removed

* @return the element removed from the queue

* @throws EmptyCollectionException if the queue is empty

* @throws InvalidArgumentException if x > 4, or x > size of collection

*

*/

@Override

public T dequeue(int x) throws EmptyCollectionException,

InvalidArgumentException {

}

/**

* Returns (without removing) the element that is at place x in the queue.

* Precondition: x must be less than 5, x must be less than size

* Note: indexing from 0: 0 == front element, 1 == second element, etc.

*

* @return the element at the front of the queue

* @throws EmptyCollectionException if the queue is empty

* @throws InvalidArgumentException if x > 4, or x > size of collection

* @param x the specified index of the element to return

*/

@Override

public T first(int x) throws EmptyCollectionException,

InvalidArgumentException {

}

/**

* Returns an ArrayList of the first three nodes in the queue

*

* @return ArrayList> array list of nodes

* @throws EmptyCollectionException if the queue is empty

*/

@Override

public ArrayList> firstThreeNodes() throws

EmptyCollectionException {

}

/**

* Returns an ArrayList of the first three elements in the queue

*

* @return ArrayList array list of elements

* @throws DataStructures.EmptyCollectionException

*/

@Override

public ArrayList firstThreeElements() throws EmptyCollectionException {

if (isEmpty()) {

throw new EmptyCollectionException ("firstThreeElements(): empty "

+ "queue");

}

frontThreeElements.clear();

LinearNode curr = front;

for (int i = 0; i < 3 && i < size(); i++) {

frontThreeElements.add(i, curr.getElement());

curr = curr.getNext();

}

return frontThreeElements;

}

/**

* Adding a specific element to the end of the queue

*

* @param element

*/

@Override

public void enqueue(T element) {

}

/**

* Removes the element at the front of queue and returns a reference to it

*

* @return

* @throws EmptyCollectionException

*/

@Override

public T dequeue() throws EmptyCollectionException {

}

/**

* Returns a reference to the element at the front of the queue

*

* @return

* @throws EmptyCollectionException

*/

@Override

public T first() throws EmptyCollectionException {

}

/**

* Returns true if the collection contains no elements

*

* @return true if the collection is empty

*/

@Override

public boolean isEmpty() {

return numNodes == 0;

}

/**

* Returns the number of elements in the collection

*

* @return the number of elements as an int

*/

@Override

public int size() {

return numNodes;

}

/**

* Returns a string representation of the collection

*

* @return a string representation of the collection

*/

@Override

public String toString() {

StringBuilder sb = new StringBuilder("");

LinearNode curr = front;

for (int i = 0; i < size(); i++) {

sb.append(curr.getElement().toString());

if (i < size() - 1) {

sb.append (", ");

}

curr = curr.getNext();

}

return sb.toString();

}

}