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Re: BitSet.[x]or does (not) grow BitSet
Mark Wielaard wrote:
>
> I don't mind changing one or the other as long as they agree on the
> result.
>
> The problem with my original statement was that it talked about growing
> the BitSet which is not actually what these tests check. What they check
> is the following:
>
> - Given
> BitSet a = {1,2,3}
> BitSet b = {3,4,5}
> BitSet c = a.xor(b);
> - Is the result
> - c = {1,2}
> since bits 4 and 5 were not explicitly set or cleared in a.
> or
> - c = {1,2,4,5}
> since bits 3 and 5 are set in b.
>
> The language of BitSet.or() and BitSet.xor() is not clear to me about
> this issue. I arbitrarily took the interpretation of the first test. But
> since you recently rewrote the BitSet implementation for Classpath I am
> easily convinced that it should be the other way around :)
Well, a quick test on JDK 1.4 shows that Sun grows their BitSets (I
purposefully spaced the bits to be beyond the 64-bit boundaries of long,
to prove that growth is occuring):
$ cat Blah.java
class Blah
{
public static void main(String[] args)
{
BitSet a = new BitSet();
a.set(1);
a.set(65);
BitSet b = new BitSet();
b.set(1);
b.set(129);
System.out.println(a + " " + b);
a.xor(b);
System.out.println(a);
}
}
$ java Blah
{1, 65} {1, 129}
{65, 129}
--
This signature intentionally left boring.
Eric Blake ebb9@email.byu.edu
BYU student, free software programmer