<p> This class implements the <code>Comparator</code> interface. You
should consider whether or not it should also implement the <code>Serializable</code>
interface. If a comparator is used to construct an ordered collection
such as a <code>TreeMap</code>, then the <code>TreeMap</code>
will be serializable only if the comparator is also serializable.
As most comparators have little or no state, making them serializable
is generally easy and good defensive programming.
</p>