Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.java.programmer > #32977
| From | Eric Sosman <esosman@comcast-dot-net.invalid> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: Java primitive variable objects |
| Date | 2015-11-02 17:47 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <n18p21$7eu$1@dont-email.me> (permalink) |
| References | <33c95894-2638-4484-af5d-545701d34372@googlegroups.com> <n18lj7$1it$1@news.albasani.net> |
On 11/2/2015 4:46 PM, Jan Burse wrote:
> Hi,
>
> Switch off autoboxing and unboxing, and you can't
> compile most of your stuff below. Which explains
> the behaviour.
>
> Bye
>
> P.S.: BTW autoboxing has improved so that
> you can even compile and execute the
> following code:
>
> public static void p(Number n) {
> System.out.println("n.getClass()="+n.getClass());
> }
>
> public static void main(String[] args) {
> p((byte)1);
> p((short)1);
> p(1);
> p(1L);
> p(0.1);
> p(0.1f);
> }
>
> The result will be:
>
> n.getClass()=class java.lang.Byte
> n.getClass()=class java.lang.Short
> n.getClass()=class java.lang.Integer
> n.getClass()=class java.lang.Long
> n.getClass()=class java.lang.Double
> n.getClass()=class java.lang.Float
>
> But you wont be able to compile:
>
> p('A');
... because Character is not a subclass of Number. Change
the parameter of p() from Number to Object, though, and it will
compile and run fine, and will also work with
p(true);
... illustrating the boxing conversions of non-numbers.
> P.P.S.: It is recommended to call Integer.valueOf()
> and Long.valueOf() instead of new Integer() or new Long(),
> since both will give cached value objects for small ranges.
Nitpick: JLS promises this for Integers (-128 through 127), for
Characters ('\u0000' through '\u007f'), and for Boolean (true and
false), but does not promise that any Bytes, Shorts, Longs, Floats,
or Doubles are cached. A given Java implementation *may* cache other
values and types, but is not required to do so. (IMHO the promises
are rather silly, but that's just MHO.)
--
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM
Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-02 10:11 -0800
Re: Java primitive variable objects Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-02 14:15 -0500
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-02 13:03 -0800
Re: Java primitive variable objects Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-02 16:29 -0500
Re: Java primitive variable objects Jan Burse <janburse@fastmail.fm> - 2015-11-02 22:46 +0100
Re: Java primitive variable objects Jan Burse <janburse@fastmail.fm> - 2015-11-02 22:52 +0100
Re: Java primitive variable objects Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-02 17:47 -0500
Re: Java primitive variable objects Joerg Meier <joergmmeier@arcor.de> - 2015-11-05 22:19 +0100
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-05 13:31 -0800
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-07 22:21 -0500
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-09 04:52 -0800
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 08:54 -0500
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-09 07:27 -0800
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 10:51 -0500
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-09 08:28 -0800
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 11:57 -0500
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-09 10:13 -0800
Re: Java primitive variable objects Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-09 13:28 -0500
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 14:53 -0500
Re: Java primitive variable objects Nigel Wade <nmw@ion.le.ac.uk> - 2015-11-10 09:27 +0000
Re: Java primitive variable objects "Jeffrey H. Coffield" <jeffrey@digitalsynergyinc.com> - 2015-11-09 10:44 -0800
Re: Java primitive variable objects Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-09 18:59 +0000
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 15:02 -0500
Re: Java primitive variable objects Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-09 22:57 +0000
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 19:16 -0500
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-09 20:55 -0500
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 22:13 -0500
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-09 20:40 -0500
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 22:23 -0500
Re: Java primitive variable objects Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-09 14:00 +0000
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-09 07:18 -0800
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-09 20:43 -0500
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-09 19:38 -0500
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 20:26 -0500
Re: Java primitive variable objects Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-10 02:10 +0000
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-09 22:12 -0500
Re: Java primitive variable objects Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-10 13:01 +0000
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-10 12:23 -0500
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-10 10:10 -0800
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-10 22:08 -0500
Re: Java primitive variable objects Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-10 20:05 +0000
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-10 13:21 -0800
Re: Java primitive variable objects Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-10 23:30 +0000
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-10 20:58 -0500
Re: Java primitive variable objects Gene Wirchenko <genew@telus.net> - 2015-11-10 22:30 -0800
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-10 21:58 -0500
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-10 21:56 -0500
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-10 22:19 -0500
Re: Java primitive variable objects Arne Vajhøj <arne@vajhoej.dk> - 2015-11-10 22:42 -0500
Re: Java primitive variable objects Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-10 23:07 -0500
Re: Java primitive variable objects Eric Douglas <e.d.programmer@gmail.com> - 2015-11-10 06:06 -0800
Re: Java primitive variable objects Lew <lewbloch@gmail.com> - 2015-11-16 14:47 -0800
csiph-web