backwarditerator.java

《Java与模式》一书的源代码

package com.javapatterns.iterator.copsandsales;

public class BackwardIterator implements Iterator
{
    public BackwardIterator(ShoppingCart aCart)
    {
        cart = aCart;
    }

    public void first()
    {
        state = cart.count() - 1;
    }

    public void next()
    {
        if (!isDone())
        {
            state--;
        }
    }

    public boolean isDone()
    {
        if (state < 0)
        {
            return true;
        }
        return false;
    }

    public Object currentItem()
    {
        return cart.currentItem(state);
    }

    private int state;
    private ShoppingCart cart;
}