package chap1;

import java.util.Iterator;

public class LinkedQueue<Item> implements Iterable<Item>

{

private Node<Item> tail;

private Node<Item> head;

private int N;

public boolean isEmpty()

{

return (0 == N);

}

public int size()

{

return N;

}

public void enqueue(Item item)

{

Node<Item> oldLast = tail;

tail = new Node<Item>();

tail.item = item;

tail.next = null;

if(0 == N)

{

head = tail;

}

else

{

oldLast.next = tail;

}

N++;

}

public Item dequeue()

{

if(this.isEmpty())

{

return null;

}

Item item = head.item;

head = head.next;

if(this.isEmpty())

{

tail = null;

}

N--;

return item;

}

@Override

public Iterator<Item> iterator()

{

return new LinkedListIterator<Item>(head);

}

}