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

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

Newsgroups	comp.lang.java.programmer
Date	2013-01-02 04:51 -0800
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

Show all headers | 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