Object-Oriented Techniques - Java - page 316

In Example 8-4 , MediaFancy shows how operations (methods) can be added to enumera-
tions; the toString() method is overridden for the “book” value of this enum.

Example 8-4. structure/MediaFancy.java
/** An example of an enum with method overriding */
public

public enum enum MediaFancy {

/** The enum constant for a book, with a method override */
BOOK {
public public String toString () { return return "Book" ; }

},
/** The enum constant for a Music CD */
MUSIC_CD ,
/** ... */
MUSIC_VINYL ,
MOVIE_VHS ,
MOVIE_DVD ;

/** It is generally disparaged to have a main() in an enum;
* please forgive this tiny demo class for doing so.
*/
public public static void main ( String [] args ) {

MediaFancy [] data = { BOOK , MOVIE_DVD , MUSIC_VINYL };
for

static void

for ( MediaFancy mf : data ) {
System . out . println ( mf );

}

}

}

Running the MediaFancy program produces this output:

Book
MOVIE_DVD
MUSIC_VINYL

That is, the Book values print in a “user-friendly” way compared to the default way the other
values print. In real life you'd want to extend this to all the values in the enum .

Finally, EnumList , in Example 8-5 , shows how to list all the possible values that a given
enum can take on; simply iterate over the array returned by the enum class's inherited val-
ues() method.

Example 8-5. structure/EnumList.java