Re: Random Enum

From:

Roedy Green <see_website@mindprod.com.invalid>

Newsgroups:

comp.lang.java.help

Date:

Tue, 25 Aug 2009 01:30:10 -0700

Message-ID:

<mr7795ta7b6ud8ikbqnp34lsj06kr6rha2@4ax.com>

On Mon, 24 Aug 2009 16:32:09 -0700, markspace <nospam@nowhere.com>
wrote, quoted or indirectly quoted someone who said :

static Enum<?> randomEnum( Enum<?> e )
    {
        return random( e.getDeclaringClass() );
    }

    private static final Random rand = new Random();

    public static <E extends Enum<E>> E random( Class<E> clazz )
    {
        E[] values = clazz.getEnumConstants();
        return values[rand.nextInt( values.length )];
    }

Two questions that may be of interest to the general audience.

1. What happens if you do simply "e.values()", rather than the
roundabout "getDeclaringClass" and "getEnumConstants"?

2. how do you get away with "E[] values"? Seems to me arrays and
generics are like trying to get oil and water to mix.
What type is getEnumConstants actually returning at run time?

--
Roedy Green Canadian Mind Products
http://mindprod.com

http://thecovemovie.com : The Cove: a documentary about Japan's secret atrocities against dolphins.