Groups > comp.lang.java.programmer > #20869

Why is that in JDK8: value used in lambda expression shuld be effectively final?

X-Received	by 10.224.190.193 with SMTP id dj1mr25435623qab.6.1357131064639; Wed, 02 Jan 2013 04:51:04 -0800 (PST)
Received	by 10.49.34.135 with SMTP id z7mr6967068qei.1.1357131064577; Wed, 02 Jan 2013 04:51:04 -0800 (PST)
Path	csiph.com!aioe.org!news.glorb.com!ee4no11686830qab.0!news-out.google.com!k2ni3609qap.0!nntp.google.com!ee4no11571599qab.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups	comp.lang.java.programmer
Date	Wed, 2 Jan 2013 04:51:04 -0800 (PST)
Complaints-To	groups-abuse@google.com
Injection-Info	glegroupsg2000goo.googlegroups.com; posting-host=95.116.88.210; posting-account=QuOrbQoAAADk1Ytmd4kkfWK7_Nh1pnw_
NNTP-Posting-Host	95.116.88.210
User-Agent	G2/1.0
MIME-Version	1.0
Message-ID	<c885bedb-977c-49b4-a10a-b9cdd3df1dd9@googlegroups.com> (permalink)
Subject	Why is that in JDK8: value used in lambda expression shuld be effectively final?
From	jeti789@web.de
Injection-Date	Wed, 02 Jan 2013 12:51:04 +0000
Content-Type	text/plain; charset=ISO-8859-1
Xref	csiph.com comp.lang.java.programmer:20869

Show key headers only | View raw

I'm currently plaing with JDK8 and using lambda-8-b69-windows-i586-17_dec_2012. I wonder why this does not compile:

List<Integer> ints = new ArrayList<>();
ints.add(1);
ints.add(2);
ints.add(3);

int sum = 0;
ints.forEach(i -> {sum += i;});

The compiler error is "value used in lambda expression shuld be effectively final"

However, this here compiles:

int sumArray[] = new int[] { 0 };
ints.forEach(i -> {sumArray[0] += i;});

I'm a bit confused now. Does this mean that JDK8 closures are no true closures or is this a bug in my IDE (IDEA 12)?

Thanks, Oliver

Back to comp.lang.java.programmer | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Why is that in JDK8: value used in lambda expression shuld be effectively final? jeti789@web.de - 2013-01-02 04:51 -0800
  Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-02 14:15 +0000
    Re: Why is that in JDK8: value used in lambda expression shuld be   effectively final? Robert Klemme <shortcutter@googlemail.com> - 2013-01-07 23:08 +0100
  Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-02 09:46 -0800
  Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-05 07:01 -0800

csiph-web