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From: markspace <markspace@nospam.nospam>
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Subject: Re: Usefulness of "final" (Was: Re: Inserting In a List)
Date: Sun, 07 Apr 2013 09:02:57 -0700
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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.

If you'd like to point out where you think JCIP or the JLS says that the 
above class is thread safe, I'll be happy to show what sections I think 
say differently.  At worst, one of us will learn something. ;-)