/**
 * An enumerative type that defines legal moves on a two-dimensional grid.
 * 
 * One could use integers or characters to represent moves. For example, 1,
 * 2, 3, 4 could designate up, down, left and right. However, the compiler would
 * not be able to detect errors such as <tt>move = 5</tt>, because 5 is a
 * valid value for an integer. By using an enumerative type, that kind of
 * errors can be detected at compile-time.
 */

public enum Move {

    Up, Down, Left, Right;

    /**
     * Caching the array to avoid regenerating it several times
     */

    public static final Move[] moves = Move.values();
}