Groups > comp.lang.java.programmer > #22365

Re: abbreviated generic syntax

From	Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid>
Newsgroups	comp.lang.java.programmer
Subject	Re: abbreviated generic syntax
Date	2013-02-19 11:38 -0600
Organization	A noiseless patient Spider
Message-ID	<kg0d9s$q1i$1@dont-email.me> (permalink)
References	<0h93i8pcopf17145fus96g7vams86hocat@4ax.com> <c1f51ff4-5827-4171-a60d-410e0582d98f@googlegroups.com> <6le5i8d6o3hsod9n20q6d15g36nb2vllin@4ax.com>

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On 2/18/2013 5:35 PM, Roedy Green wrote:
> On Mon, 18 Feb 2013 12:29:53 -0800 (PST), Lew <lewbloch@gmail.com>
> wrote, quoted or indirectly quoted someone who said :
>
>> The diamond operator distinguishes the generics usage.
>
> OK, that is obvious, but would it break any code?

In the Java typing system, a generic type that is used without generics 
(aka a raw type) is a very distinct type. "List" is not "List<?>" nor is 
it "List<Object>" nor any other value that you stick in those brackets 
[1]. If you didn't have the diamond operator, it would be ambiguous as 
to whether inferred type arguments or the actual raw type was desired. 
Imagine scenarios like:

Collections.singletonList(new List());

[1] This is *really* annoying because the type of List.class is 
Class<List> (a rare type), not Class<List<?>>. If you thought raw types 
were hard to use, rare types pretty much require you to sprinkle your 
code with @SuppressWarnings.

-- 
Beware of bugs in the above code; I have only proved it correct, not 
tried it. -- Donald E. Knuth

Thread

abbreviated generic syntax Roedy Green <see_website@mindprod.com.invalid> - 2013-02-17 20:26 -0800
  Re: abbreviated generic syntax Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-02-18 01:02 -0800
  Re: abbreviated generic syntax Barb Knox <see@sig.below> - 2013-02-18 22:41 +1300
    Re: abbreviated generic syntax Donkey Hottie <donkey@fredriksson.dy.fi> - 2013-02-18 12:58 +0200
    Re: abbreviated generic syntax Arne Vajhoej <arne@vajhoej.dk> - 2013-02-18 07:20 -0500
      Re: abbreviated generic syntax Arne Vajhoej <arne@vajhoej.dk> - 2013-02-18 07:27 -0500
  Re: abbreviated generic syntax Arne Vajhoej <arne@vajhoej.dk> - 2013-02-18 07:23 -0500
  Re: abbreviated generic syntax "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2013-02-18 19:33 +0000
  Re: abbreviated generic syntax BGB <cr88192@hotmail.com> - 2013-02-18 13:46 -0600
  Re: abbreviated generic syntax Lew <lewbloch@gmail.com> - 2013-02-18 12:29 -0800
    Re: abbreviated generic syntax Robert Klemme <shortcutter@googlemail.com> - 2013-02-18 22:49 +0100
      Re: abbreviated generic syntax Lew <lewbloch@gmail.com> - 2013-02-18 13:51 -0800
    Re: abbreviated generic syntax Roedy Green <see_website@mindprod.com.invalid> - 2013-02-18 15:35 -0800
      Re: abbreviated generic syntax lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-19 08:56 +0000
        Re: abbreviated generic syntax lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-19 12:30 +0000
      Re: abbreviated generic syntax Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2013-02-19 16:21 +0000
      Re: abbreviated generic syntax Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2013-02-19 11:38 -0600
      Re: abbreviated generic syntax Arne Vajhoej <arne@vajhoej.dk> - 2013-02-19 12:45 -0500
        Re: abbreviated generic syntax BGB <cr88192@hotmail.com> - 2013-02-19 15:20 -0600

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