public class MyQueue<Item> implements Iterator<Item> {
private int N;
private Node first, last;
private class Node {
Item item;
Node next;
}
public boolean isEmpty() {return first == null;}
public int size() {return N;}
public Item poll() {
Item item = first.item;
first = first.next;
//what is missing here?
N--;
return item;
}
public void add(Item item) {
Node oldlast = last;
last = new Node();
last.item = item;
last.next = null;
if(isEmpty()) first = last;
else oldlast.next = last;
N++;
}
public Iterator<Item> iterator() {
return MyIterator();
}
private class MyIterator implements Iterator<Item> {
Node current = first;
public boolean hasNext() {return current != null;}
public Item next() {
Item item = current.item;
current = current.next;
return item;
}
}
}
