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Groups > comp.lang.java.programmer > #39959
| From | Arne Vajhøj <arne@vajhoej.dk> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: switch is shared declaration |
| Date | 2023-05-28 13:42 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <u503q0$va0v$1@dont-email.me> (permalink) |
| References | <af8aa265-141f-4887-8bae-83a9b2a0f9c1n@googlegroups.com> <u4ve27$3t8pn$1@gwaiyur.mb-net.net> <u4vhsg$sea0$1@dont-email.me> <u4vk7b$3t8pn$8@gwaiyur.mb-net.net> |
On 5/28/2023 9:16 AM, Marcel Mueller wrote: > Am 28.05.23 um 14:36 schrieb Eric Sosman: >> On 5/28/2023 7:31 AM, Marcel Mueller wrote: >>> Shouldn't this be a problem too because the 2nd switch label bypasses >>> the initialization of s? >> >> The `case 1:' part *is* the initialization of `s'. There is a >> *declaration* of `s' in the `case -1:' part, but the declaration >> does nothing (here) to initialize the `s' reference. >> >> If we added another case to the switch, say >> >> default: >> System.out.println(s); >> break; >> >> ... the compiler would complain that `s' might be used without >> being initialized, true. But the code as shown does not try >> to retrieve any value from `s', so the compiler holds its peace. > > So ist is only valid because of the optimization? Not a traditional optimization. The check if things used are guaranteed to be initialized just do not apply. > String s; > is a default constructor call. No. s is just a reference not pointing to any object. > s = "1"; > is an assignment operator call. An assignment. > I expected the latter to be invalid without the first (unless String is > a trivial type). You can not assign to a variable not declared no matter whether it is simple or not. But I suspect that was not what you meant. String s; s = "1"; is sort of equivalent to C: char *s; s = "1"; Arne
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switch is shared declaration "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-05-24 05:15 -0700
Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-24 12:57 -0400
Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-24 13:16 -0400
Re: switch is shared declaration "e.d.pro...@gmail.com" <e.d.programmer@gmail.com> - 2023-05-24 11:05 -0700
Re: switch is shared declaration Michael Jung <miju@golem.phantasia.org> - 2023-05-28 12:57 +0200
Re: switch is shared declaration Marcel Mueller <news.5.maazl@spamgourmet.org> - 2023-05-28 13:31 +0200
Re: switch is shared declaration Eric Sosman <esosman@comcast-dot-net.invalid> - 2023-05-28 08:36 -0400
Re: switch is shared declaration Marcel Mueller <news.5.maazl@spamgourmet.org> - 2023-05-28 15:16 +0200
Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-28 13:42 -0400
Re: switch is shared declaration Arne Vajhøj <arne@vajhoej.dk> - 2023-05-28 13:43 -0400
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