Implementing an LinkedQueue class in java

Problem:

Write a program that implements an LinkedQueue in java.

Output:

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Solution:

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01	public class LinkedQueue<E> implements Queue<E> {

02	private Node<E> head = new Node<E>(); // dummy node

03	private int size;

04

05	public void add(E element) {

06	head.prev = head.prev.next = new Node<E>(element, head.prev, head);

07

++size;

08

}

09

10	public E element() {

11	if (size == 0) {

12	throw new java.util.EmptyStackException();

13

}

14	return head.next.element; // front of queue // next <--> prev

15

}

16	public boolean isEmpty() {

17	return (size == 0);

18

}

19

20	public E remove() {

21	if (size == 0) {

22	throw new java.util.EmptyStackException();

23

}

24	E element = head.next.element; // next <--> prev

25	head.next = head.next.next; // next <--> prev

26	head.next.prev = head; // next <--> prev

27

--size;

28	return element;

29

}

30	public int size() {

31	return size;

32

}

33	private static class Node<E> {

34	E element;

35	Node<E> prev;

36	Node<E> next;

37

Node() {

38	this.prev = this.next = this;

39

}

40	Node(E element, Node<E> prev, Node<E> next) {

41	this.element = element;

42	this.prev = prev;

43	this.next = next;

44

}

45

}

46

}