Re: Random Enum

From:

markspace <nospam@nowhere.com>

Newsgroups:

comp.lang.java.help

Date:

Mon, 24 Aug 2009 16:32:09 -0700

Message-ID:

<h6v7ts$nbm$1@news.eternal-september.org>

Lew wrote:

public class RandomEnum // untested, not even compiled yet
{
  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 )];
  }
}

This is what I would have suggested. It's pretty simple really. You
could define a similar method that takes an enum rather than a class and
returns a random value, it's just as easy to call getDeclaringClass() on
an enum and use this one method.

package randomenum;

import java.lang.annotation.ElementType;
import java.util.Random;
import java.util.concurrent.TimeUnit;

public class RandomEnum
{

     public static void main( String[] args )
     {
         System.out.println( "Random TimeUnit: " +
                 randomEnum( TimeUnit.SECONDS ) );
         System.out.println( "Random ElementType: " +
                 randomEnum( ElementType.FIELD ) );
     }

     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 )];
     }

}

OUTPUT:
run:
Random TimeUnit: MICROSECONDS
Random ElementType: LOCAL_VARIABLE
BUILD SUCCESSFUL (total time: 2 seconds)