Collections - The Java Programming Language - page 882

public static <E extends Enum<E>> EnumSet<E> of(E first, E... rest)
Creates an EnumSet containing all the specified enum values.
Finally, the range method takes two enum constants that define the first
and last elements that the enum set will contain. If first and last are in
the wrong order then IllegalArgumentException is thrown.
Once you have obtained an enum set you can freely modify it in
whatever way you need.
EnumSet uses a bit-vector internally so it is both compact and efficient.
The iterator returned by iterator is not the usual fail-fast iterator of oth-
er collections. It is a weakly consistent iterator that returns the enum
values in their natural orderthe order in which the enum constants were
declared. A weakly consistent iterator never throws ConcurrentModifica-
tionException , but it also may not reflect any changes that occur while
the iteration is in progress.
21.9.2. EnumMap
The EnumMap<Kextends Enum<K>,V> is a special map that uses enum values
as keys. All values in the map must come from the same enum type.
Just like EnumSet the enum values are ordered by their natural order, and
the iterator is weakly consistent.
Suppose you were writing an application that dynamically builds and
displays an on-line form, based on a description written in a structured
format such as XML . Given the set of expected form elements as an enum
enum FormElements { NAME, STREET, CITY, ZIP }
you could create an enum map to represent a filled in form, where
the keys are the form elements and the values are whatever the user
entered.