public abstract class Cs132AbstractList implements Cs132List
{
    // text thinks it is important that this be here...
    public Cs132AbstractList()
    {
        // does nothing...?
    }

    // Purpose: returns true iff list has no elements
    public boolean isEmpty()
    {
        return (this.size() == 0);
    }

    // NOTE that any concrete class of this must implement size() ---
    // how to do THAT *is* implementation-dependent;

    // Purpose: add given data newElement to beginning of list.
    public void addFirst(Object newElement)
    {
        this.add(0, newElement);
    }

    // Purpose: add given data newElement to end of list.
    public void addLast(Object newElement)
    {
        this.add( this.size(), newElement );
    }

    // NOTE that our add() is implementation-dependent, however;

    // Purpose: IF list is not empty, return FIRST element in list.
    //          (we're deferring, for NOW, what to do if list IS empty.)
    public Object getFirst()
    {
        return this.get(0);
    }

    // Purpose: IF the list is not empty, return the LAST element in list.
    //          (we're deferring, for NOW, what to do if the list IS empty.)
    public Object getLast()
    {
        return this.get( this.size()-1 );
    }

    // NOTE that our get() is implementation-dependent, too

    // NOTE that our remove() is implementation-dependent, too

    // Purpose: empties the list 
    public void clear()
    {
        while (this.size() > 0)
        {
            Object ignoreMe = this.remove(0);
        }
    }
}