RFR 8170348: Appendable.appendN(char, int) method to append multiple copies of char

Ivan Gerasimov ivan.gerasimov at oracle.com
Sun Dec 11 20:35:26 UTC 2016

Thank you Roger for the comments!

On 08.12.2016 1:28, Roger Riggs wrote:
> Hi Ivan,
> A few comments...
> Appendable.appendN default method:
>    I'd expect many time n is small so allocating a new StringBuilder 
> every time seems
>    not optimal.  A simple loop with append(c) would have fewer 
> (memory) side effects.
>    And in particular for n=0, it could avoid doing anything.
The rationale here was to implement `all or nothing` approach.
If we add chars one by one in a loop and hit OOM, then the Appendable 
would be partially modified, which is not good.
A special case for the size of zero can be added, of course.

> AbstractStringBuilder:
>    I agree with Claes' comment suggesting that IAE for negative 
> lengths is a pain
>    and defining it to append 0 would be natural in many use cases.
I see that most votes are for throwing the exception if n is negative.
Let's leave it this way!

> MethodHandleImpl.toString():
>    You could beneficially replace StringBuffer with StringBuilder 
> while you are there.
>    (and maybe pre-size the builder).
Sure, let's use StringBuilder.
I wasn't sure how to easily calculate the required capacity of the 
builder here though.

Please find the updated webrev here:

With kind regards,

More information about the core-libs-dev mailing list