Re: Why must and must not be "final" ?

From:
"NeoGeoSNK" <ny1022@gmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
22 Nov 2006 20:57:08 -0800
Message-ID:
<1164257828.129155.323920@e3g2000cwe.googlegroups.com>
"Thomas Hawtin =D0=B4=B5=C0=A3=BA
"

Andreas Leitgeb wrote:

An extra note:
This doesn't mean that you couldn't share non-final
references between the outer and inner class! Just
wrap it up into some container-class.

Simple example:

class Outer {
   final TextField[] tf = new TextField[1];
   class Inner
   {
       // use and modify tf[0] at will.
   }
   void init()
   {
       // use and modify tf[0] at will.
   }
}


I'm not sure how useful an example that is. IIRC, it does mean (from
1.5) that you can guarantee that tf[0] is non-null, even with unsafe
publishing. For local classes you can do much the same (but use
AtomicReference):

String foo(String arg) {
     final AtomicReference<String> argRef =
         new AtomicReference<String>(arg);

     new Object() {
         void bar() {
             argRef.set('<'+argRef.get()+'>');
         }
     }.bar();

     return argRef.get();
}

But please don't. :)

Tom Hawtin


Thanks Tom Hawtin
And I think AtomicReference is more complex than Inner class:)

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