RFR [8054221] StringJoiner imlementation optimization

Ivan Gerasimov ivan.gerasimov at oracle.com
Tue Aug 5 11:55:39 UTC 2014

Thanks you Martin!

On 05.08.2014 9:52, Martin Buchholz wrote:
> I'm truly unsure whether it's worth optimizing for size < 2.

With saving results of compaction in merge, this case will become a 
little more common.
This way X.merge(Y); Y.toString(); can work a bit faster.

> But if we do that, I think we should optimize size == 0 as well, thus:
> if (addLen == 0 && size <= 1)
>  return (size == 0) ? "" : elts[0];
Yes, done.

> ---
>   240         if (other == this) {
> I doubt that optimizing specially for a self-merge is worthwhile.

You're probably correct, it's not worth coding that.
I just was upset that combining with itself doesn't work as well as in 
other cases, that's why I implemented it.
I'll remove it.

Here's the updated webrev:

> When you're thinking of doing that, you probably really want
> Strings.repeat(String, int copies)
> https://code.google.com/p/guava-libraries/source/browse/guava/src/com/google/common/base/Strings.java?r=5cc3b0b33392b02ff95a4ce5f291c439b5b1406e#154
> I suggest adding repeat to String!

Yes, it would be a useful addition.
In addition, there might be overloads with a delimiter, prefix and 
suffix :-)

Sincerely yours,

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