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From: Wanja Gayk <brixomatic@yahoo.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Usefulness of "final" (Was: Re: Inserting In a List)
Date: Sun, 7 Apr 2013 19:20:22 +0200
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In article <kjs56q$hib$1@dont-email.me>, markspace 
(markspace@nospam.nospam) says...
> 
> On 4/7/2013 8:28 AM, Wanja Gayk wrote:
> 
> > public class Foo{
> >   private int value;
> >   private Foo(int value){this.value=value;}
> >   public static Foo createFoo(int value){return new Foo(value);}
> >   public int getValue(){return value;}
> > }
> >
> > ..is both immutable, thread safe and can't be overridden either, without
> 
> No, he doesn't say that, and no, this class isn't thread safe.  Normal 
> POJO classes aren't thread safe.  Adding a factory method doesn't help.
> 
> In order for this class to be thread safe 'value' would have to be made 
> visible somehow.  You need volatile, a synchronized block, or something 
> similar.  Please read the JLS (and JCIP, again) and note section 17 
> Threads and Locks.  The whole point of that section is that regular 
> writes aren't thread safe.

You're right in that regard, in rare cases a second thread could see the 
"0" default. But you know it's check mate in 1 draw, my friend. 
Just watch this:

public class Foo{
 private volatile int value;
 private Foo(int value){this.value=value;}
 public static Foo createFoo(int value){return new Foo(value);}
 public int getValue(){return value;}
}

Now that's immutable and thread safe and still there is no "final" used.
Check mate!

Kind regards,
-Wanja-

-- 
..Alesi's problem was that the back of the car was jumping up and down 
dangerously - and I can assure you from having been teammate to 
Jean Alesi and knowing what kind of cars that he can pull up with, 
when Jean Alesi says that a car is dangerous - it is. [Jonathan Palmer]

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