// CSE 143, Winter 2009, Marty Stepp
// This class captures common code shared by both the ArrayAnythingList
// and LinkedAnythingList.
// An abstract class is a good way to provide a partially implemented class, or
// a partial implementation of an interface.  Notice that the header of this
// class claims to implement the AnythingList interface, but the file doesn't
// write all of the methods.  Java allows this file to compile because it knows
// the abstract class must be extended to complete it.  If a subclass of
// AbstractAnythingList doesn't implement all the rest of the AnythingList
// interface's methods, that subclass will not compile.  

public abstract class AbstractAnythingList<E> implements AnythingList<E> {
    // Adds the given value to the end of the list.
    public void add(E value) {
        add(size(), value);
    }
    
    // Returns true if this list contains the given value as an element.
    public boolean contains(E value) {
        return indexOf(value) >= 0;
    }
    
    // Returns true if there are no elements in this list.
    public boolean isEmpty() {
        return size() == 0;
    }
}