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Re: Generics ?

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Subject Re: Generics ?
Date Sat, 17 Dec 2011 10:54:24 -0800
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On 12/17/2011 10:20 AM, Knute Johnson wrote:
> Which brings me back to my real question, can you
> extend a generic class and still be generic?


Yes of course.


 > model.addElement("test");
 > ^
 > required: E#1
 > found: String
 > reason: actual argument String cannot be converted to E#1 by method
 > invocation conversion


The problem is that you don't *have* a generic type.  You have a 
parametrized type of String.  Otherwise, you can't stick a String in 
that thing.  Which is why the compiler is complaining.

Roedy's example compiles because it matches what you did.  It 
parametrizes the type to String because that's what you have.

No, you cannot have a "generic" class, then assume that you can also use 
"string" as a type.  Generics specifically prevent that.

You could put a bound on the type of E, like <E super String> and I 
think that would work (I didn't test it).  But since that is basically 
String, CharSequence, or Object, it's really kinda limiting while being 
baroque at the same time.  I'd just use "String" or "CharSequence" or 
"Object" unless you're really sure that the ability to parametrize that 
type is really important.

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Thread

Generics ? Knute Johnson <nospam@knutejohnson.com> - 2011-12-15 21:48 -0800
  Re: Generics ? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-12-15 22:03 -0800
    Re: Generics ? Tassilo Horn <tassilo@member.fsf.org> - 2011-12-16 08:30 +0100
      Re: Generics ? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-12-16 00:08 -0800
  Re: Generics ? Roedy Green <see_website@mindprod.com.invalid> - 2011-12-16 02:10 -0800
    Re: Generics ? Knute Johnson <nospam@knutejohnson.com> - 2011-12-16 22:01 -0800
      Re: Generics ? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-12-16 23:30 -0800
        Re: Generics ? Knute Johnson <nospam@knutejohnson.com> - 2011-12-17 10:20 -0800
          Re: Generics ? markspace <-@.> - 2011-12-17 10:54 -0800
            Re: Generics ? Knute Johnson <nospam@knutejohnson.com> - 2011-12-17 11:25 -0800
              Re: Generics ? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-12-17 21:20 -0800
                Re: Generics ? "Qu0ll" <Qu0llSixFour@gmail.com> - 2011-12-18 21:08 +1100
                Re: Generics ? Lew <lewbloch@gmail.com> - 2011-12-18 08:17 -0800
                Re: Generics ? markspace <-@.> - 2011-12-18 08:43 -0800
          Re: Generics ? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-12-17 11:33 -0800
            Re: Generics ? Knute Johnson <nospam@knutejohnson.com> - 2011-12-17 11:40 -0800
              Re: Generics ? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-12-17 11:47 -0800
              Re: Generics ? Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-12-17 15:13 -0500
      Re: Generics ? Roedy Green <see_website@mindprod.com.invalid> - 2011-12-17 02:46 -0800
  Re: Generics ? "John B. Matthews" <nospam@nospam.invalid> - 2011-12-17 11:18 -0500
    Re: Generics ? Knute Johnson <nospam@knutejohnson.com> - 2011-12-17 11:16 -0800

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