Java Sorting: Comparator vs Comparable Tutorial

http://lkamal.blogspot.com/2008/07/java-sorting-comparator-vs-comparable.html
So in effect, using the comparable interface gives you a default sort order of your own making, whereas the comparator is more flexible as it allows you define a whole series of different types of sorting that can be applied to a whole lot of different types of objects.
http://www.java-tips.org/blog/java-se/difference-between-comparable-and-comparator-interface.html