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Re: unchecked conversion warning.

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On Tuesday, June 19, 2012 2:14:06 PM UTC-7, Robert Klemme wrote:
> On 18.06.2012 21:28, Lew wrote:
> > Robert Klemme wrote:
> >> I totally agree.  Btw, there is one interesting detail: JavaDoc of
> >> Collections.synchronizedList() and the other synchronized*() methods
> >> explicitly state that the mutex used for synchronizing is that of the
> >> returned object:
> >>
> >> http://docs.oracle.com/javase/7/docs/api/java/util/Collections.html#synchronizedList%28java.util.List%29
> >
> > I see no such promise there.
> 
> <quote>
> It is imperative that the user manually synchronize on the returned list 
> when iterating over it:
> 
>    List list = Collections.synchronizedList(new ArrayList());
>        ...
>    synchronized (list) {
>        Iterator i = list.iterator(); // Must be in synchronized block
>        while (i.hasNext())
>            foo(i.next());
>    }
> 
> 
> Failure to follow this advice may result in non-deterministic behavior.
> </quote>
> 
> Pardon, my wording was wrong: it's not explicitly stated but it follows 
> immediately from the quote.  For me that was "explicit" enough. ;-)

Okay, I see what you're saying, but it doesn't follow immediately. 
You have to go through at least two logical steps.

> No, it also matters in cases like the example quoted above, i.e. when 
> you need to perform multiple operations on the Vector instance: when the 
> monitor which the Vector instance uses internally is different from the 
> one used for the external synchronization then you do not have thread 
>safety.  Depending on the logic anything from inconsistent contents to 
> CME can happen. 

Nope.

The successive operations can synchronize on a second monitor without 
harm even though the individual methods synchronize on the first one.
Provided all your code uses that monitor, of course, in addition to the 
default one.

But then the Javadoc's advice wouldn't be right, so therefore you are.

Thanks for the eye-opener.

-- 
Lew

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unchecked conversion warning. Jens - 2012-05-30 15:32 +0200
  Re: unchecked conversion warning. Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2012-05-30 13:48 +0000
    Re: unchecked conversion warning. Jens - 2012-05-30 15:52 +0200
  Re: unchecked conversion warning. Robert Klemme <shortcutter@googlemail.com> - 2012-05-30 07:54 -0700
    Re: unchecked conversion warning. Jens - 2012-05-31 22:23 +0200
      Re: unchecked conversion warning. Lew <lewbloch@gmail.com> - 2012-05-31 13:40 -0700
      Re: unchecked conversion warning. Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-05-31 16:50 -0400
        Re: unchecked conversion warning. Lew <lewbloch@gmail.com> - 2012-05-31 17:18 -0700
        Re: unchecked conversion warning. Robert Klemme <shortcutter@googlemail.com> - 2012-06-01 08:14 +0200
          Re: unchecked conversion warning. Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-01 08:48 -0400
            Re: unchecked conversion warning. Robert Klemme <shortcutter@googlemail.com> - 2012-06-01 07:32 -0700
            Re: unchecked conversion warning. Roedy Green <see_website@mindprod.com.invalid> - 2012-06-10 12:16 -0700
              Re: unchecked conversion warning. Martin Gregorie <martin@address-in-sig.invalid> - 2012-06-10 22:08 +0000
                Re: unchecked conversion warning. Lew <noone@lewscanon.com> - 2012-06-10 17:09 -0700
                Re: unchecked conversion warning. Martin Gregorie <martin@address-in-sig.invalid> - 2012-06-11 01:31 +0000
        Re: unchecked conversion warning. Jim Janney <jjanney@shell.xmission.com> - 2012-06-01 08:41 -0600
          Re: unchecked conversion warning. Patricia Shanahan <pats@acm.org> - 2012-06-01 08:44 -0700
            Re: unchecked conversion warning. markspace <-@.> - 2012-06-01 09:08 -0700
            Re: unchecked conversion warning. Gene Wirchenko <genew@ocis.net> - 2012-06-01 09:31 -0700
            Re: unchecked conversion warning. Jim Janney <jjanney@shell.xmission.com> - 2012-06-01 11:02 -0600
            Re: unchecked conversion warning. Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-01 13:54 -0400
              Re: unchecked conversion warning. Patricia Shanahan <pats@acm.org> - 2012-06-01 16:44 -0700
                Re: unchecked conversion warning. Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-01 20:24 -0400
                Re: unchecked conversion warning. Patricia Shanahan <pats@acm.org> - 2012-06-01 19:36 -0700
          Re: natural/native language capabilities (was: unchecked conversion warning.) Jim Janney <jjanney@shell.xmission.com> - 2012-06-01 11:01 -0600
        Re: unchecked conversion warning. Roedy Green <see_website@mindprod.com.invalid> - 2012-06-10 12:13 -0700
        Re: unchecked conversion warning. Arne Vajhøj <arne@vajhoej.dk> - 2012-06-20 19:28 -0400
  Re: unchecked conversion warning. Broad Liyn <broadliyn@gmail.com> - 2012-06-10 21:52 -0700
    Re: unchecked conversion warning. Lew <noone@lewscanon.com> - 2012-06-10 23:50 -0700
    Re: unchecked conversion warning. Patricia Shanahan <pats@acm.org> - 2012-06-11 00:06 -0700
      Re: unchecked conversion warning. Robert Klemme <shortcutter@googlemail.com> - 2012-06-16 15:17 +0200
        Re: unchecked conversion warning. Lew <lewbloch@gmail.com> - 2012-06-18 12:28 -0700
          Re: unchecked conversion warning. Robert Klemme <shortcutter@googlemail.com> - 2012-06-19 23:14 +0200
            Re: unchecked conversion warning. Lew <lewbloch@gmail.com> - 2012-06-19 17:15 -0700
      Re: unchecked conversion warning. Arne Vajhøj <arne@vajhoej.dk> - 2012-06-20 19:22 -0400
    Re: unchecked conversion warning. Arne Vajhøj <arne@vajhoej.dk> - 2012-06-20 19:20 -0400

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