java.io.Writer uses CharSequence.toString()

[Brent Christian]

Hi,

This idea has been brought up before [1].

I concur with Pavel's assessment.  I would add that now that latin-1 
Strings are stored in a more compact form in JDK 9 ("Compact Strings" 
[2]), the performance profile of string data is further complicated.

Thanks,
-Brent

1. https://bugs.openjdk.java.net/browse/JDK-6206838
2. https://bugs.openjdk.java.net/browse/JDK-8054307
On 07/29/2016 10:21 AM, Pavel Rappo wrote:
> Once again, while I agree in some places it could have been done a bit better
> probably, I would say it's good to a have a look at benchmarks first.
>
> If they show there's indeed a big difference between
>
>     char[] copy = new chars[charSequence.length()];
>     String s = charSequence.toString();
>     s.getChars(0, s.length, copy, 0);
>
> and
>
>     char[] copy = new chars[charSequence.length()];
>     charSequence.getChars(0, charSequence.length(), copy, 0);
>
> it could justify an increase in complexity of CharBuffer.append or introducing a
> new default method (getChars/fillInto) into CharSequence. Possibly. Or maybe
> not. Because there might be some nontrivial effects we are completely unaware of.
>
> Btw, what do you mean by "extract char[]" from StringBuilder? Do you want
> StringBuilder to give away a reference to its char[] outside? If not, than
> what's the difference between "extract char[]" from StringBuilder and "use
> String" in your algorithm?
>
> The bottom line is whatever you suggest would likely need a good justification.
> To me it's not immediately obvious that something like this
>
>      public CharBuffer append(CharSequence csq) {
>          if (csq == null) {
>              put("null");
>          } else if (csq instanceof StringBuilder) {
>              char[] chars = new char[csq.length()];
>              ((StringBuilder) csq).getChars(0, csq.length(), chars, 0);
>              put(chars);
>          } else if (csq instanceof StringBuffer) {
>              char[] chars = new char[csq.length()];
>              ((StringBuffer) csq).getChars(0, csq.length(), chars, 0);
>              put(chars);
>          } else if (csq instanceof CharBuffer) {
>              CharBuffer buffer = (CharBuffer) csq;
>              int p = buffer.position();
>              put(buffer);
>              buffer.position(p);
>          } else {
>              for (int i = 0; i < csq.length(); i++) {
>                  put(csq.charAt(i));
>              }
>          }
>          return this;
>      }
>
> is better than this (what's there today)
>
>      public CharBuffer append(CharSequence csq) {
>          if (csq == null)
>              return put("null");
>          else
>              return put(csq.toString());
>      }
>
>> On 29 Jul 2016, at 15:12, ecki at zusammenkunft.net wrote:
>>
>> Hello,
>>
>> Have to agree with Fabian handling CharSequences (and special case StringBuilder) is pretty weak, in CharBuffer.append(CharSequence) you see the same toString. I would expect it to do:
>> - Instamceof String -> use it
>> - Instance of StringBuilder -> extract char[] and iterate
>> - Instance of CharBuffer -> handle
>> - Otherwise: Loop over charAt
>>
>> (the otherwise might be a tradeof between allocation and (not)inlined bounds checks)
>>
>> Alternative would be a CharSequence.fillInto(char[])
>>
>> BTW wouldn't it be create if char[] implements CharSequence?
>>
>> Gruss
>> Bernd
>> --
>> http://bernd.eckenfels.net
>>  From Win 10 Mobile
>>
>> Von: Fabian Lange
>