Groups > comp.lang.java.programmer > #29406

Re: Java blunders

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From	Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups	comp.lang.java.programmer
Subject	Re: Java blunders
Date	Mon, 28 Jul 2014 16:39:27 -0400
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On 7/28/2014 4:23 PM, Josip Almasi wrote:
> On 07/24/2014 03:53 AM, Roedy Green wrote:
>> On Wed, 23 Jul 2014 19:55:09 -0400, Arne Vajhøj <arne@vajhoej.dk>
>> wrote, quoted or indirectly quoted someone who said :
>>
>>> But is it a problem in real world programming?
>>>
>>> I have never seen a problem due to this.
>>
>>
>> The most common error is like this:
>>
>> out.println ( "the answer is " +
>> a + b
>> + ".");
>>
>> you must write that as:
>>
>> out.println ( "the answer is " + (a + b) + ".");
>
> I think you guys missed worst thing with java concatenation, and it's
> got nothing to do with operator.
> It's about how operator gets interpreted:
>
> out.println ( new StringBuffer("the answer is ").append(new
> StringBuffer(a + b)).append(new StringBuffer("."));

     Why do you think this is so?  javac 1.8.0_11 compiles it to
the equivalent of

	out.println(new StringBuilder()
	    .append("the answer is ")
	    .append(a + b)
	    .append(".")
	    .toString());

... and I think all javac's have done so for a long time (but I
don't have them available for checking).

> It's three new objects, all synchronized.

     ... for suitable values of "three" (i.e., 2) and "all" (0).

> OK I haven't read the spec for a while but that's it IIRC, spec requires
> it that way.

     StringBuilder replaced StringBuffer for this purpose in Java 1.5,
just under ten years ago.  I guess that counts as "a while."  ;-)

> And if you want to avoid the garbage, you need to
>
> StringBuilder shit = new StringBuilder();
> shit.append("the answer is ");
> shit.append(a + b);
> shit.append(".");
> and another line to get the string.

     Um, er, no.

-- 
esosman@comcast-dot-net.invalid

Thread

Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-22 11:41 -0700
  Re: Java blunders Daniele Futtorovic <da.futt.news@laposte.net> - 2014-07-22 21:12 +0200
    Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-22 19:46 -0400
      Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 04:14 -0700
  Re: Java blunders Joerg Meier <joergmmeier@arcor.de> - 2014-07-22 23:47 +0200
    Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 04:23 -0700
      Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-23 12:32 +0000
        Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-23 08:55 -0400
          Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 06:21 -0700
        Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-23 19:53 -0400
          Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 18:49 -0700
      Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-23 19:52 -0400
  Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-22 19:44 -0400
    Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 04:27 -0700
      Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-23 19:55 -0400
        Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 18:53 -0700
          Re: Java blunders Joerg Meier <joergmmeier@arcor.de> - 2014-07-24 11:24 +0200
            Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-25 06:34 -0700
          Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-24 19:31 -0400
            Re: Java blunders Gene Wirchenko <genew@telus.net> - 2014-07-25 13:22 -0700
              Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-25 17:17 -0400
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-25 23:12 +0000
                Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 09:06 -0700
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-26 20:11 +0000
                Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-26 17:27 -0400
                Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-27 10:49 -0700
                Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-27 10:10 -0700
                Re: Java blunders Gene Wirchenko <genew@telus.net> - 2014-07-28 13:53 -0700
                Re: Java blunders Stuart <DerTopper@web.de> - 2014-07-30 08:05 +0200
                Re: Java blunders Sebastian <news@seyweiler.dyndns.org> - 2014-07-30 11:12 +0200
                Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-27 10:13 -0700
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-27 18:28 +0000
                Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-27 14:46 -0400
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-27 21:18 +0000
                Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-27 18:10 -0400
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-28 01:25 +0000
                Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-28 08:02 -0400
                Re: Java blunders Mike Amling <mamling@chaff.us> - 2014-07-31 13:26 -0500
                Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-31 14:48 -0400
                Re: Java blunders "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-07-28 13:22 +0100
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-28 12:52 +0000
                Re: Java blunders Joerg Meier <joergmmeier@arcor.de> - 2014-07-28 23:38 +0200
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-28 23:17 +0000
                Re: Java blunders Silvio <silvio@internet.com> - 2014-07-29 13:34 +0200
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-29 12:45 +0000
                Re: Java blunders Silvio <silvio@internet.com> - 2014-07-29 17:10 +0200
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-29 16:29 +0000
                Re: Java blunders lipska the kat <lipskathekat@example.com> - 2014-07-29 20:15 +0100
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-29 22:02 +0000
                Re: Java blunders Silvio <silvio@internet.com> - 2014-07-29 22:43 +0200
                Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-29 22:10 +0000
                Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-27 19:18 -0500
                Re: Java blunders Gene Wirchenko <genew@telus.net> - 2014-07-28 13:54 -0700
                Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-31 23:07 -0400
                Re: Java blunders James Hostick <james.hostick@gmail.com> - 2014-08-01 22:10 -0700
            Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 08:31 -0700
              Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-26 21:04 +0000
                Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-27 10:51 -0700
                Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-28 08:50 -0700
                Re: Java blunders Joerg Meier <joergmmeier@arcor.de> - 2014-07-28 23:42 +0200
              Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-31 23:04 -0400
          Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-28 22:23 +0200
            Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-28 16:39 -0400
              Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-29 00:11 +0200
              Re: Java blunders Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2014-07-30 12:07 +0300
                Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-30 08:05 -0400
    Re: Java blunders Wanja Gayk <brixomatic@yahoo.com> - 2014-07-25 01:34 +0200
      Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-24 19:43 -0400
  Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-22 21:02 -0500
    Re: Java blunders Leif Roar Moldskred <leifm@huldreskog.lan> - 2014-07-23 02:01 -0500
      Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 18:58 -0700
      Re: Java blunders thinbluernime <thinbluernime3@gmail.com> - 2014-07-25 03:55 +0000
        Re: Java blunders Leif Roar Moldskred <leifm@huldreskog.lan> - 2014-07-25 00:32 -0500
          Re: Java blunders thinbluernime <thinbluernime3@gmail.com> - 2014-07-26 07:28 +0000
            Re: Java blunders "Gavino" <invalid@invalid.invalid> - 2014-07-26 19:43 +0200
        Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-25 06:36 -0700
          Re: Java blunders "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-07-25 15:47 +0100
            Re: Java blunders David Postill <david.postill@gmail.com> - 2014-07-25 18:29 +0200
            Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 09:27 -0700
        Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-25 06:37 -0700
    Re: Java blunders Joerg Meier <joergmmeier@arcor.de> - 2014-07-23 13:17 +0200
      Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 06:27 -0700
    Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 04:44 -0700
      Re: Java blunders Silvio <silvio@internet.com> - 2014-07-23 16:23 +0200
        Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-23 12:02 -0400
          Re: Java blunders Silvio <silvio@internet.com> - 2014-07-24 11:37 +0200
            Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-28 22:37 +0200
        Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 09:33 -0700
          Re: Java blunders thinbluernime <thinbluernime3@gmail.com> - 2014-07-25 03:57 +0000
        Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-23 21:38 -0400
          Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 18:59 -0700
            Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-24 07:33 +0000
          Re: Java blunders Silvio <silvio@internet.com> - 2014-07-24 11:47 +0200
            Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-24 19:34 -0400
              Re: Java blunders Silvio <silvio@internet.com> - 2014-07-25 08:48 +0200
                Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-25 08:07 -0400
                Re: Java blunders "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-07-25 13:54 +0100
                Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-31 22:53 -0400
            Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-25 07:04 -0700
        Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-28 22:01 +0200
      Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-28 21:56 +0200
    Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 06:28 -0700
      Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-23 08:33 -0500
    Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-23 21:34 -0400
      Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-23 19:06 -0700
      Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-23 22:11 -0500
        Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-24 07:36 +0000
          Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-24 19:39 -0400
            Re: Java blunders "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-07-25 13:40 +0100
        Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-24 19:38 -0400
          Re: Java blunders Gene Wirchenko <genew@telus.net> - 2014-07-25 13:30 -0700
  Re: Java blunders taqmcg@gmail.com - 2014-07-23 11:26 -0700
    Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-23 15:14 -0400
      Re: Java blunders thinbluernime <thinbluernime3@gmail.com> - 2014-07-25 04:07 +0000
        Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-07-25 08:35 -0400
          Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 09:41 -0700
        Re: Java blunders Wanja Gayk <brixomatic@yahoo.com> - 2014-08-03 16:41 +0200
          Re: Java blunders Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-03 11:31 -0400
    Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-23 22:41 -0500
      Re: Java blunders taqmcg@gmail.com - 2014-07-24 10:09 -0700
        Re: Java blunders "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-07-25 13:22 +0100
        Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-25 20:34 -0500
          Re: Java blunders "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-07-28 13:33 +0100
            Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-28 08:35 -0500
        Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 09:44 -0700
          Re: Java blunders Martin Gregorie <martin@address-in-sig.invalid> - 2014-07-26 23:36 +0000
  Re: Java blunders Gene Wirchenko <genew@telus.net> - 2014-07-23 20:48 -0700
    Re: Java blunders Silvio <silvio@internet.com> - 2014-07-24 11:56 +0200
      Re: Java blunders Silvio <silvio@internet.com> - 2014-07-24 16:07 +0200
        Re: Java blunders Gene Wirchenko <genew@telus.net> - 2014-07-25 13:38 -0700
          Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 10:02 -0700
    Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-24 19:29 -0400
      Re: Java blunders Gene Wirchenko <genew@telus.net> - 2014-07-25 13:45 -0700
    Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 10:53 -0700
  Re: Java blunders Wanja Gayk <brixomatic@yahoo.com> - 2014-07-25 01:28 +0200
  Re: Java blunders "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-07-25 14:16 +0100
  Re: Java blunders Joerg Meier <joergmmeier@arcor.de> - 2014-07-25 17:39 +0200
  Re: Java blunders Roedy Green <see_website@mindprod.com.invalid> - 2014-07-26 16:21 -0700
  Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-28 23:59 +0200
    Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-29 00:41 +0200
      Re: Java blunders Josip Almasi <joe@vrspace.org> - 2014-07-29 01:54 +0200
    Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-31 22:38 -0400
    Re: Java blunders Arne Vajhøj <arne@vajhoej.dk> - 2014-07-31 22:39 -0400
  Re: Java blunders w.tom.adams@gmail.com - 2014-07-30 07:57 -0700
    Re: Java blunders Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2014-07-30 10:22 -0500

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