class ArrayList<T> implements Iterable<T> {
	private T[] _underlyingStorage = (T[]) Object[128];
	private int _numElements = 0;

	public Iterator<T> iterator () {
		return new ArrayListIterator<T>();
	}

	public void add (T o) {
		if (_numElements == _underlyingStorage.length) {
			// Grow array if necessary ...
		}
		_underlyingStorage[_numElements++] = o;
	}

	private class ArrayListIterator<T> implements Iterator<T> {
		// Write your code here...	


	}
}

Complete the implementation of the ArrayListIterator inner-class shown above.
It should behave in the following ways: hasNext() should return true if the
list is non-empty; otherwise, it should return false.
remove() should just throw an UnsupportedOperationExecption().
next() should function like the Iterator in the circular linked-list described
during lecture -- once it gets to the end of the list, it should "loop back"
to the beginning. For example, if the following code were executed:

	final ArrayList<Integer> al = new ArrayList<Integer>();
	al.add(new Integer(1));
	al.add(new Integer(2));
	al.add(new Integer(4));
	final Iterator<Integer> iterator = al.iterator();
	System.out.println(iterator.next());
	System.out.println(iterator.next());
	System.out.println(iterator.next());
	System.out.println(iterator.next());
	System.out.println(iterator.next());

then the program should output the numbers 1, 2, 4, 1, 2.