Re: EnumSet and varargs

From:
"John B. Matthews" <nospam@nospam.invalid>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 17 Sep 2008 07:48:45 -0400
Message-ID:
<nospam-307F36.07484517092008@news.motzarella.org>
In article <rlo0d41ho6nt85m5jfjibuske8f5stl7hq@4ax.com>,
 Roedy Green <see_website@mindprod.com.invalid> wrote:

On Tue, 16 Sep 2008 23:39:51 GMT, Wojtek <nowhere@a.com> wrote, quoted
or indirectly quoted someone who said :

closest is
http://java.sun.com/j2se/1.5.0/docs/api/java/util/EnumSet.html#of(E,%20E...)
, but it needs an initial single parameter. null is not an option.


All those variants are just ways of handling an EnumSet with a small
number of elements more efficiently.

[...]

Wojtek : In addition to the vararg constructor, consider offering an
EnumSet constructor. This would allow clients to use EnumSet's set
operations, e.g. union, intersection, complement, etc:

<code>
import java.util.*;

public class EnumTest {

    enum Bar { ONE, TWO, THREE, FOUR; }

    public EnumTest(EnumSet<Bar> bars) {
        showBars(bars);
    }

    public EnumTest(Bar... bars) {
        List<Bar> barList = Arrays.asList(bars);
        EnumSet<Bar> barSet = EnumSet.copyOf(barList);
        showBars(barSet);
    }
    
    private static void showBars(EnumSet<Bar> bars) {
        for (Bar b : bars) System.out.print(b.name() + " ");
        System.out.println();
    }

    public static void main(String[] args) {
        EnumTest test1 = new EnumTest(
            EnumSet.complementOf(EnumSet.of(Bar.THREE)));
        Bar[] bars = { Bar.ONE, Bar.TWO, Bar.FOUR };
        EnumTest test2 = new EnumTest(bars);
    }
}
</code>

--
John B. Matthews
trashgod at gmail dot com
home dot woh dot rr dot com slash jbmatthews

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