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Groups > comp.lang.java.programmer > #23603

Re: <? extends String>

From Steven Simpson <ss@domain.invalid>
Newsgroups comp.lang.java.programmer
Subject Re: <? extends String>
Date 2013-04-23 23:22 +0100
Organization A noiseless patient Spider
Message-ID <e5ej4a-o77.ln1@s.simpson148.btinternet.com> (permalink)
References (6 earlier) <atggb3Fsg5U1@mid.dfncis.de> <e02i4a-8m3.ln1@s.simpson148.btinternet.com> <9h4i4a-kvp.ln1@tempest.fredriksson.dy.fi> <dfgi4a-1n7.ln1@s.simpson148.btinternet.com> <7a008cc4-c436-41b0-a0d3-af24852fb708@googlegroups.com>

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On 23/04/13 22:12, Lew wrote:
> Steven Simpson wrote:
>> Also, just because a class is final now, it might not be in the future.
> Not applicable to 'java.lang.String'.
>
> It will never be non-final.

[...]

> You're solving a non-existent problem.

I concede that my arguments given so far are not compelling.

> The finality and immutability of 'String'
> are wired into the promises of the Java language and the type's special treatment by
> the compiler and runtime.

A particularly good point that I hadn't considered.


> But defensive programming against scenarios that
> won't occur is not really a best practice.

Perhaps I now have a more compelling argument.  Consider:

import java.util.List;

class ExtendsTest {
     // Two methods with identical functionality
     static void foo1(List<? extends String> list) { }
     static void foo2(List<String> list) { }

     interface Bar<T> {
         void bar(List<? extends T> list);
     }

     static class Adapter implements Bar<String> {
         public void bar(List<? extends String> list) {
             foo1(list);
             foo2(list); // error
         }
     }
}

Suppose foo1 and foo2 may have been written with no generic interface in 
mind, perhaps even before Bar was conceived.  Bar comes along, and the 
functionalities of foo1/foo2 are deemed suitable in meeting Bar.bar's 
contract.  How does one now adapt foo2 to Bar?

-- 
ss at comp dot lancs dot ac dot uk

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Thread

exec problem is JDK 1.7.0_21 Roedy Green <see_website@mindprod.com.invalid> - 2013-04-16 15:48 -0700
  Re: exec problem is JDK 1.7.0_21 Lew <lewbloch@gmail.com> - 2013-04-16 16:48 -0700
  Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-20 13:00 +0300
  Re: exec problem is JDK 1.7.0_21 Joerg Meier <joergmmeier@arcor.de> - 2013-04-20 15:13 +0200
    Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-20 19:07 +0300
      Re: exec problem is JDK 1.7.0_21 markspace <markspace@nospam.nospam> - 2013-04-20 09:24 -0700
        Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-20 19:34 +0300
          Re: exec problem is JDK 1.7.0_21 markspace <markspace@nospam.nospam> - 2013-04-20 11:01 -0700
            Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 00:25 +0300
          Re: exec problem is JDK 1.7.0_21 Joerg Meier <joergmmeier@arcor.de> - 2013-04-20 22:03 +0200
            Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 00:29 +0300
              Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-20 21:56 +0000
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 08:31 +0300
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-21 11:08 +0000
                Re: exec problem is JDK 1.7.0_21 Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-04-21 13:43 -0300
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 23:12 +0300
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-21 21:17 +0000
                Re: exec problem is JDK 1.7.0_21 Arne Vajhøj <arne@vajhoej.dk> - 2013-04-27 22:49 -0400
              Re: exec problem is JDK 1.7.0_21 Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-04-20 15:03 -0700
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 08:26 +0300
                Re: exec problem is JDK 1.7.0_21 "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-04-21 14:30 +0100
                Re: exec problem is JDK 1.7.0_21 Knute Johnson <nospam@knutejohnson.com> - 2013-04-21 09:20 -0700
                Re: exec problem is JDK 1.7.0_21 markspace <markspace@nospam.nospam> - 2013-04-21 11:31 -0700
                Re: exec problem is JDK 1.7.0_21 Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-04-21 16:06 -0300
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-21 19:47 +0000
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-21 23:01 +0000
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 23:29 +0300
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 23:45 +0300
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-21 21:38 +0000
                Re: exec problem is JDK 1.7.0_21 Knute Johnson <nospam@knutejohnson.com> - 2013-04-21 18:49 -0700
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-22 09:36 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-22 10:39 +0100
                Re: exec problem is JDK 1.7.0_21 Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-04-22 07:43 -0700
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-22 19:33 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-23 07:30 +0100
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-22 21:07 +0000
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-23 23:28 +0300
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-23 21:05 +0000
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-24 11:22 +0300
                Re: exec problem is JDK 1.7.0_21 Martin Gregorie <martin@address-in-sig.invalid> - 2013-04-24 20:22 +0000
                Re: exec problem is JDK 1.7.0_21 Nigel Wade <nmw@ion.le.ac.uk> - 2013-04-24 11:24 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 23:23 +0300
            Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-21 00:40 +0300
              Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-23 10:48 +0100
                Re: exec problem is JDK 1.7.0_21 Donkey Hottie <donkey@fredriksson.dy.fi> - 2013-04-23 13:31 +0300
                <? extends String> (was: exec problem is JDK 1.7.0_21) Steven Simpson <ss@domain.invalid> - 2013-04-23 14:55 +0100
                Re: <? extends String> lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-04-23 16:37 +0100
                Re: <? extends String> Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-04-23 08:50 -0700
                Re: <? extends String> lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-04-23 17:30 +0100
                Re: <? extends String> Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-04-23 09:58 -0700
                Re: <? extends String> Donkey Hottie <donkey@fredriksson.dy.fi> - 2013-04-23 21:06 +0300
                Re: <? extends String> lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-04-23 19:33 +0100
                Re: <? extends String> Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-04-23 12:26 -0700
                Re: <? extends String> lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-04-24 09:08 +0100
                Re: <? extends String> Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-04-23 16:28 -0300
                Re: <? extends String> (was: exec problem is JDK 1.7.0_21) Lew <lewbloch@gmail.com> - 2013-04-23 14:12 -0700
                Re: <? extends String> Steven Simpson <ss@domain.invalid> - 2013-04-23 23:22 +0100
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-23 19:56 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-23 23:31 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-23 23:39 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-24 09:29 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-24 10:26 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-24 13:11 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-24 22:24 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-25 11:49 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-25 10:19 +0100
                Re: exec problem is JDK 1.7.0_21 "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-04-25 09:02 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-25 11:47 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-25 09:50 +0100
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-25 10:07 +0100
                Re: exec problem is JDK 1.7.0_21 "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-04-27 08:44 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-26 20:17 +0300
                Re: exec problem is JDK 1.7.0_21 Steven Simpson <ss@domain.invalid> - 2013-04-27 09:22 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-27 12:39 +0300
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-23 23:17 +0300
                Re: exec problem is JDK 1.7.0_21 Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-04-23 17:32 -0300
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-24 10:39 +0300
                Re: exec problem is JDK 1.7.0_21 "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-04-25 09:02 +0100
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-25 11:59 +0300
                Re: exec problem is JDK 1.7.0_21 Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-04-25 18:38 -0300
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-28 10:57 +0300
                Re: exec problem is JDK 1.7.0_21 Arne Vajhøj <arne@vajhoej.dk> - 2013-04-27 22:35 -0400
                Re: exec problem is JDK 1.7.0_21 Sven Köhler <remove-sven.koehler@gmail.com> - 2013-04-28 09:23 +0300
                Re: exec problem is JDK 1.7.0_21 Arne Vajhøj <arne@vajhoej.dk> - 2013-04-28 09:52 -0400
  Re: exec problem is JDK 1.7.0_21 Stanimir Stamenkov <s7an10@netscape.net> - 2013-04-20 17:52 +0300
    Re: exec problem is JDK 1.7.0_21 Arne Vajhøj <arne@vajhoej.dk> - 2013-04-27 22:31 -0400

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