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Groups > comp.lang.java.programmer > #25397

Re: StringBuilder.append and CharSequence

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Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> wrote:
> On 2013-09-28 01:16, Andreas Leitgeb allegedly wrote:
>> markspace <markspace@nospam.nospam> wrote:
>>> On 9/27/2013 10:31 AM, Daniele Futtorovic wrote:
>>>> On 2013-09-27 15:30, Andreas Leitgeb allegedly wrote:
>>>>> Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> wrote:
>>>>>> I'd make the toString() as follows to be on the safe side:
>>>>>>    char[] cs = new char[ m_len ];
>>>>>>    Arrays.fill( cs, m_ch );
>>>>>>    return new String(cs);
>>>>> If this is the ONLY safe side, then there wouldn't be a point
>>>>> in implementing a CharSequence in the first place for my task.
>>>> Why not? The Standard API's StringBuilder#append(CharSequence), AFAICS,
>>>> does not call toString() -- granted, the JavaDoc stipulates nothing to
>>>> that effect.
>>> I read Andreas's comment as "there's not point introducing a new type if 
>>> a repeated string is just always turned into a regular String anyway."
>> Yes, that's about it.
>> The "new type" is the ChSeq from a few posts upthread.
>> The "repeated string" is a possibly long repetition of
>> just a single char, compactly represented by ChSeq...
>
> Yes, but using the ChSeq (as it was introduced) to append it to a
> StringBuilder WILL NOT, as the JSE currently stands, result in the
> invocation of toString(). So you are safe to go.

As much as I'd like this answer... "safe" is a strong word, and
seeing a particular Java implementation *not* call toString() is
sufficient for my task for now, but not not sufficient for "safe".

> Then, as far as the implementation of toString() is concerned (which
> only matters if other API use your ChSeq's)

My application definitely doesn't call toString() on the ChSeq-instances,
but a debugger might do it.
I thought of implementing toString() to create a String like
  "42000000 times '*'"
making it even more suitable for debugger inspection than the canonical
expansion, but unfortunately that would definitely break the specified
contract of CharSequence.toString().

I think, this topic has been thoroughly discussed now.
Thanks to all who participated.

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Thread

StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-25 14:19 +0000
  Re: StringBuilder.append and CharSequence markspace <markspace@nospam.nospam> - 2013-09-25 13:02 -0700
    Re: StringBuilder.append and CharSequence markspace <markspace@nospam.nospam> - 2013-09-25 18:34 -0700
      Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-26 17:37 +0000
        Re: StringBuilder.append and CharSequence Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-09-26 23:11 +0200
          Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-27 13:30 +0000
            Re: StringBuilder.append and CharSequence Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-09-27 19:31 +0200
              Re: StringBuilder.append and CharSequence markspace <markspace@nospam.nospam> - 2013-09-27 13:45 -0700
                Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-27 23:16 +0000
                Re: StringBuilder.append and CharSequence Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-09-29 04:58 +0200
                Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-30 20:02 +0000
  Re: StringBuilder.append and CharSequence Arne Vajhøj <arne@vajhoej.dk> - 2013-09-25 20:57 -0400
    Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-26 18:01 +0000
      Re: StringBuilder.append and CharSequence Arne Vajhøj <arne@vajhoej.dk> - 2013-09-26 15:47 -0400
        Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-26 20:48 +0000
          Re: StringBuilder.append and CharSequence Arne Vajhøj <arne@vajhoej.dk> - 2013-09-26 16:58 -0400
            Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-09-27 12:52 +0000
              Re: StringBuilder.append and CharSequence Arne Vajhøj <arne@vajhoej.dk> - 2013-10-04 20:59 -0400
                Re: StringBuilder.append and CharSequence Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-10-05 12:51 +0000
  Re: StringBuilder.append and CharSequence Sven Köhler <remove-sven.koehler@gmail.com> - 2013-09-27 15:41 +0300

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