Re: a question about alias of reference

From:
"Mike Schilling" <mscottschilling@hotmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 18 Jul 2010 23:07:35 -0700
Message-ID:
<i20q3c$tgf$1@news.eternal-september.org>
"ClassCastException" <zjkg3d9gj56@gmail.invalid> wrote in message
news:i20me2$hm5$1@news.eternal-september.org...

On Sat, 17 Jul 2010 23:35:39 -0700, Mike Schilling wrote:

"ClassCastException" <zjkg3d9gj56@gmail.invalid> wrote in message
news:i1tto7$f8o$2@news.eternal-september.org...

On Sat, 17 Jul 2010 11:21:26 -0700, Mike Schilling wrote:

Or, to paraphrase everyone else who's answered this question, Java
does not have aliasing of references.


Not quite. It comes close, though, with the right constructs: reference
a points to object 0, which has an instance field b that points to
object 1. a.b = null changes the latter. In a sense, reference b is
aliased if we have a reference c that also points to object 0 so c.b ==
null now as well.


My point was that there's no Java construct that's a reference to a
reference [1], but you're quite right that there are references to
objects that contain references.

1. That is, nothing like the C++

    char *p;
    char * &q = p;


That is to say, a reference in and of itself can't be treated as a first-
class object. You can explicitly encapsulate it in one (and the
java.lang.reference classes do so, with almost-immutable ones that the GC
can set to null).

Similarly to how Java lacks first-class functions but allows a one-method
interface like Comparator or ActionListener whose implementations'
instances can be passed around for similar purposes.


Yup. Java has one hammer and thus everything is a nail.

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