Opgave 2 - QueueList

package queueopgaver;

import java.util.NoSuchElementException;

/**
 * An implementation of a queue as a list.
 */
public class QueueList implements QueueI {
    private Node head;
    private Node tail;

    /**
     * Constructs an empty queue.
     */
    public QueueList() {
        head = null;
    }

    /**
     * Checks whether this queue is empty.
     *
     * @return true if this queue is empty
     */
    @Override
    public boolean isEmpty() {
        return head == null;
    }

    /**
     * Adds an element to the tail of this queue.
     *
     * @param newElement the element to add
     */
    @Override
    public void enqueue(Object newElement) {
        Node newNode = new Node();
        newNode.data = newElement;
        if (head == null) {
            head = newNode;
            tail = newNode;
        } else {
            tail.next = newNode;
            tail = newNode;
        }
    }

    /**
     * Removes an element from the head of this queue.
     *
     * @return the removed element
     */
    @Override
    public Object dequeue() { // TODO: SOMETHING IS WRONG WITH THIS METHOD!!!
        if (head == null) {
            throw new NoSuchElementException();
        }
        Object NewElement = head.data;
        head = head.next;

        return NewElement;
    }

    /**
     * Returns the head of this queue. The queue is unchanged.
     *
     * @return the head element
     */
    @Override
    public Object getFront() {
        if (head == null) {
            throw new NoSuchElementException();
        }
        return head.data;
    }

    /**
     * The number of elements on the queue.
     *
     * @return the number of elements in the queue
     */
    @Override
    public int size() {
        int count = 0;
        Node temp = head;
        while (temp != null) {
            count++;
            temp = temp.next;
        }
        return count;
    }

    class Node {
        public Object data;
        public Node next;
    }
}