RFR: String.join(), StringJoiner additions

[Jim Gish]

That was a nice idea, but you don't want to change the value when you do 
toString().  Otherwise, if you subsequently add a new element, you're 
hosed because you've already added on the suffix.

Jim

On 04/17/2013 09:20 PM, Roger Riggs wrote:
> Hi,
>
> Can I suggest that the StringJoiner.toString() method explicitly 
> append the suffix
> to the existing StringBuilder.
>
>  152         return (value != null ? value.toString() + suffix : 
> emptyValue);
>
> Currently it will go to the trouble of creating a String from the 
> builder and then
> transparently create another StringBuilder to do the concatenation.
>
>  152         return (value != null ? value.append(suffix).toString() : 
> emptyValue);
>
> or something similar.
>
> The overhead of StringJoiner supporting prefix and suffix is lower 
> than doing it separately
> in terms of object allocations and garbage and all places that would 
> need write their
> own code to do the concatenation.
>
> Roger
>
>
> On 4/17/13 5:49 PM, Jim Gish wrote:
>> Here's an update: 
>> http://cr.openjdk.java.net/~jgish/Bugs-5015163-7172553/ 
>> <http://cr.openjdk.java.net/%7Ejgish/Bugs-5015163-7172553/>
>>
>> Jim
>>
>> On 04/17/2013 03:15 PM, Mike Duigou wrote:
>>> String::
>>>
>>> line 1253: This should use {@code } rather than <code></code>. I 
>>> think regular spaces are OK as well.   seems inappropriate.
>>>
>>> lines 2425/2467: elements may not be null either.
>>>
>>> I can tell you (or maybe it's just me) are itching to change :
>>>
>>> for (CharSequence cs: elements) {
>>> 2477             joiner.add(cs);
>>> 2478         }
>>>
>>> to:
>>>
>>> elements.forEach(joiner::add);
>>>
>>> StringJoiner::
>>>
>>> - <blockquote> isn't needed around <pre> as it's already a <div> you 
>>> probably mean to do
>>>
>>> <pre> {@code
>>> ...
>>> }</pre>
>>>
>>> for code samples.
>>>
>>> - It would be nice if the empty output generation in three arg 
>>> constructor could be suppressed unless needed. Perhaps a special 
>>> (not null please!) sentinel value?
>>>
>>> - Four arg constructor doesn't include emptyOutput in @throws NPE
>>>
>>>
>>> On Apr 11 2013, at 15:33 , Jim Gish wrote:
>>>
>>>> Please review 
>>>> http://cr.openjdk.java.net/~jgish/Bugs-5015163-7175206-7172553/ 
>>>> <http://cr.openjdk.java.net/%7Ejgish/Bugs-5015163-7175206-7172553/>
>>>>
>>>> These are changes that we made in lambda that we're now bringing 
>>>> into JDK8.
>>>>
>>>> I've made a couple of additions - making StringJoiner final and 
>>>> adding a couple of constructors to set the emptyOutput chars.
>>>>
>>>> Thanks,
>>>>    Jim
>>>>
>>>> -- 
>>>> Jim Gish | Consulting Member of Technical Staff | +1.781.442.0304
>>>> Oracle Java Platform Group | Core Libraries Team
>>>> 35 Network Drive
>>>> Burlington, MA 01803
>>>> jim.gish at oracle.com
>>>>
>>
>

-- 
Jim Gish | Consulting Member of Technical Staff | +1.781.442.0304
Oracle Java Platform Group | Core Libraries Team
35 Network Drive
Burlington, MA 01803
jim.gish at oracle.com