I'd like to create a subclass of EnumSet to implement the Comparable
interface (using my own arbitrary ordering, so that I can use the
subclass as a key in a dictionary), but I can't seem to figure
out how to do it.

I tried:

 import java.util.EnumSet;

 public abstract class Foo<E extends Enum<E>> extends EnumSet<E>
                                              implements Comparable<Foo>
 {
   public int compareTo (Foo o)
   {
     return 1;  // dummy value for now
   }
 }

The compiler says:

 Foo.java:3: cannot find symbol
 symbol  : constructor EnumSet()
 location: class java.util.EnumSet<E>
 public abstract class Foo<E extends Enum<E>> extends EnumSet<E>
                 ^
 1 error

I don't understand why it thinks there should be an EnumSet()
constructor, since I'm subclassing it as an abstract class.
Any hints or suggestions?

Thanks!
Eric