Re: EnumSet and varargs

Zig <>
Wed, 17 Sep 2008 15:52:51 -0400
On Wed, 17 Sep 2008 09:39:09 -0400, Wojtek <> wrote:

The method add() in the EnumSet implementation ALWAYS throws an
UnsupportedOperationException, so it cannot be used.

This sounds inconsistent with my knowledge, have you tried this?

Yes. At first glance it seemed the way to go. I had a loop which added
the "bars" one by one. When I ran it, it threw that exception.

Interesting. This is my test:

import java.util.*;
import java.util.concurrent.TimeUnit;

public class EnumFiddling {
  public static void main(String[] args) {
     //empty collection
     EnumSet<TimeUnit> units=EnumSet.noneOf(TimeUnit.class);

     //add one element

     //add a sequence of elements

For me, this yields the output:


I use Eclipse, and hovering over "add" showed a Javadoc which stated
that the exception was always thrown.

I see that. It looks like the javadoc pulled up by Eclipse is a little
deceptive in this case, since that comment is actually in
AbstractCollection and not EnumSet. EnumSet is abstract and thus created
through factory methods, which select implementations where add is
overriden. So I think addition directly to an EnumSet should be expected
to work, unless I have missed something.



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