Groups > comp.lang.java.programmer > #21962

String.substring in JDK 1.7.0_6+

Date	2013-02-01 19:33 +0100
From	jlp <jlp@jlp.com>
Newsgroups	comp.lang.java.programmer
Subject	String.substring in JDK 1.7.0_6+
Message-ID	<510c0a6a$0$8985$ba4acef3@reader.news.orange.fr> (permalink)
Organization	les newsgroups par Orange

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The String class was modified in JDK 1.7.0_6.
String.substring that was 0(1)  before JDK 1.7.0_6, now becomes O(n)

All is well explained at :
http://java-performance.info/changes-to-string-java-1-7-0_06/

I wrote a small test:
https://gist.github.com/4692960

java -Xms128M -Xmx128M teststring.Main 100000 1000000

On my desktop:
jdk 1.7.0_11 => 33 seconds / 252 KBytes Memory
jdk 1.6.0_38 => 25 milliseconds / 782 KBytes Memory
more than 1000 times faster ! ( Ok! for this stupid test ;-) )

I don't think it is a good improvement ! Uses less memory, but you 
retrieve it, when the object is garbaged
What do you think about this ?

-- 
Cordialement
Jean-Louis Pasturel

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String.substring in JDK 1.7.0_6+ jlp <jlp@jlp.com> - 2013-02-01 19:33 +0100
  Re: String.substring in JDK 1.7.0_6+ markspace <markspace@nospam.nospam> - 2013-02-01 10:38 -0800
    Re: String.substring in JDK 1.7.0_6+ jlp <jlp@jlp.com> - 2013-02-01 19:42 +0100
      Re: String.substring in JDK 1.7.0_6+ markspace <markspace@nospam.nospam> - 2013-02-01 10:45 -0800
        Re: String.substring in JDK 1.7.0_6+ jlp <jlp@jlp.com> - 2013-02-01 19:57 +0100
          Re: String.substring in JDK 1.7.0_6+ markspace <markspace@nospam.nospam> - 2013-02-01 11:20 -0800
  Re: String.substring in JDK 1.7.0_6+ Jan Burse <janburse@fastmail.fm> - 2013-02-01 20:34 +0100
  Re: String.substring in JDK 1.7.0_6+ Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-02-01 20:58 -0800
    Re: String.substring in JDK 1.7.0_6+ markspace <markspace@nospam.nospam> - 2013-02-01 22:55 -0800
      Re: String.substring in JDK 1.7.0_6+ Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-02-02 08:43 -0800
        Re: String.substring in JDK 1.7.0_6+ markspace <markspace@nospam.nospam> - 2013-02-02 10:56 -0800
          Re: String.substring in JDK 1.7.0_6+ Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-02-02 14:46 -0800
            Re: String.substring in JDK 1.7.0_6+ markspace <markspace@nospam.nospam> - 2013-02-02 15:31 -0800
            Re: String.substring in JDK 1.7.0_6+ Robert Klemme <shortcutter@googlemail.com> - 2013-02-03 15:09 +0100

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