Effectively final

[Serge Boulay]

not even through a reference such as an atomic boolean ? (yes, I know Brian
frowns on this stuff)

void foo(final Socket socket) {
     AtomicBoolean timedOut = new AtomicBoolean(false);
     system.setTimeout(100, ->{ timedOut.set(true); });
     socket.onData(->{ if (!timedOut.get()) System.out.println("Got data");
});
}

On Wed, Sep 14, 2011 at 2:57 PM, Neal Gafter <neal at gafter.com> wrote:

> A lambda can't modify a local variable from the enclosing scope.
>
> On Wed, Sep 14, 2011 at 11:46 AM, blackbelt1999 <
> blackbelt1999 at sbcglobal.net
> > wrote:
>
> > Is there not a fundamental difference between the original code and the
> new
> > code, namely the original code creates a new thread of execution while
> the
> > new
> > code does not? If so, can't the new code be simplified to:
> >
> >   void foo(final Socket socket) {
> >        boolean timedOut = false;
> >       system.setTimeout(100, () =>  { timedOut = true; });
> >      socket.onData(() =>  { if (!timedOut) System.out.println("Got
> data");
> > });
> >   }
> >
> > The above version .does not go through the expense of creating a new
> object
> > while providing the same behavior?
> >
> > --Alan
> >
> >
> >
> >
> > ________________________________
> > From: Steven Simpson <ss at comp.lancs.ac.uk>
> > To: lambda-dev at openjdk.java.net
> > Sent: Wed, September 14, 2011 4:10:42 AM
> > Subject: Re: Effectively final
> >
> > Just a loose end...
> >
> > On 15/08/11 15:41, Tim Fox wrote:
> > > On 15/08/2011 15:22, Steven Simpson wrote:
> > >>       void foo(final Socket socket) {
> > >>         new Runnable() {
> > >>           boolean timedOut;
> > >>           public void run() {
> > >>             system.setTimeout(100, #{ timedOut = true; });
> > >>             socket.onData(#{ if (!timedOut) System.out.println("Got
> > data");
> > >});
> > >>           }
> > >>         }.run();
> > >>       }
> > > Steven, firstly thanks for putting in the effort to look at this. And
> > > kudos for your ingenuity :)
> >
> > And yet I missed this trick!:
> >
> >   void foo(final Socket socket) {
> >     new Object() {
> >       boolean timedOut;
> >       void run() {
> >         system.setTimeout(100, () ->  { timedOut = true; });
> >         socket.onData(() ->  { if (!timedOut) System.out.println("Got
> > data");
> > });
> >       }
> >     }.run();
> >   }
> >
> > So the object doesn't have to be Runnable, and run() doesn't have to be
> > public, return void, or be called run!  That's more convenient if you
> > want to return a value, rather than doing tricks with Callable:
> >
> >   return new Object() {
> >     int run() { return 0; }
> >   }.run();
> >
> > Cheers,
> >
> > Steven
> >
> >
>
>