Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.help > #2063 > unrolled thread

Re: newbie interface question

Back to article view | Back to comp.lang.java.help

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: newbie interface question Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-27 20:43 -0400
    Re: newbie interface question Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-28 08:42 -0400
      Re: newbie interface question Lew <lewbloch@gmail.com> - 2012-08-28 14:08 -0700
      Re: newbie interface question Gene Wirchenko <genew@ocis.net> - 2012-08-28 17:21 -0700
    Re: newbie interface question Roedy Green <see_website@mindprod.com.invalid> - 2012-08-29 08:26 -0700

#2063 — Re: newbie interface question

On 8/27/2012 7:17 PM, happytoday wrote:
> Dear All,
> I am testing interface but really I can not apply what is explained in
> oracle tutorials . Could you please explain why I have errors with
> this code :
> [...]

     What "errors" do you have?  For me, the code compiles just
fine, and runs producing the output

	Cadence : 1 Gear : 1Speed:1
	Cadence : 1 Gear : 1Speed:1
	Cadence : 1 Gear : 1Speed:1
	Cadence : 1 Gear : 1Speed:1
	MB_Cadence : 1 MB_Gear : 1 MB_Speed  :1

(Follow-ups set to c.l.j.help only, dropping c.l.j.programmer.)

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

[toc] | [next] | [standalone]

#2064

On 8/28/2012 6:32 AM, happytoday wrote:
> On Aug 28, 2:43 am, Eric Sosman <esos...@ieee-dot-org.invalid> wrote:
>> On 8/27/2012 7:17 PM, happytoday wrote:
>>
>>> Dear All,
>>> I am testing interface but really I can not apply what is explained in
>>> oracle tutorials . Could you please explain why I have errors with
>>> this code :
>>> [...]
>>
>>       What "errors" do you have?  For me, the code compiles just
>> fine, and runs [...]
>>
>
> prog01_BicycleDemo_interface_trial01.java:62: printresults() in
> ACMEBicycle cannot implement printresults() in Bicycle; attempting to
> assign weaker access privileges; was public
> void printresults()
>       ^

     Aha!  So by "this code" you meant "some other piece of code
altogether," right?  Do you know how many times "ACME" appears
in the code sample you posted?  Z E R O times, that's how many.

     Unfortunately, I am not sufficiently skilled to debug code
that I cannot see.  My guess (but I'm only guessing) is that
you've converted Bicycle from a class to an interface, thus
making its methods public automatically even if you don't use
the `public' keyword.  Then (still guessing) you've written an
ACMEBicycle class that implements Bicycle, and you've tried to
give it an implementation of the printresults() method specified
by the Bicycle interface.  But the interface says printresults()
must be a `public' method, while ACMEBicycle's printresults()
isn't marked `public'.

     There are other possible explanations, but I'm tired of
guessing about unseen code and my Magic 8 Ball has a virus.

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

[toc] | [prev] | [next] | [standalone]

#2066

Eric Sosman wrote:
>happytoday wrote:
>> Eric Sosman wrote:
>>>  happytoday wrote:
>>>> I am testing interface but really I can not apply what is explained in
>>>> oracle [sic] tutorials . Could you please explain why I have errors with
>>>> this code :
>>>> [...]
>>>       What "errors" do you have?  For me, the code compiles just
>>> fine, and runs [...]
> 
>> prog01_BicycleDemo_interface_trial01.java:62: printresults() in
>> ACMEBicycle cannot implement printresults() in Bicycle; attempting to
>> assign weaker access privileges; was public
>> void printresults()
>>       ^
> 
>     Aha!  So by "this code" you meant "some other piece of code
> altogether," right?  Do you know how many times "ACME" appears
> in the code sample you posted?  Z E R O times, that's how many.
> 
>      Unfortunately, I am not sufficiently skilled to debug code
> that I cannot see.  My guess (but I'm only guessing) is that
> you've converted Bicycle from a class to an interface, thus
> making its methods public automatically even if you don't use
> the `public' keyword.  Then (still guessing) you've written an
> ACMEBicycle class that implements Bicycle, and you've tried to
> give it an implementation of the printresults() method specified
> by the Bicycle interface.  But the interface says printresults()
> must be a `public' method, while ACMEBicycle's printresults()
> isn't marked `public'.
> 
>      There are other possible explanations, but I'm tired of
> guessing about unseen code and my Magic 8 Ball has a virus.

"All indications point to No!"

The Magic Infinity Ball (you were looking at yours sideways) only 
answers "Yes" or "No" questions.

Fortunately the OP asked a "Yes" or "No" question.

-- 
Lew

[toc] | [prev] | [next] | [standalone]

#2067

On Tue, 28 Aug 2012 08:42:06 -0400, Eric Sosman
<esosman@ieee-dot-org.invalid> wrote:

[snip]

>     There are other possible explanations, but I'm tired of
>guessing about unseen code and my Magic 8 Ball has a virus.

     GIYF.  There are many Web simulations of the Magic 8-Ball.

     OP, GIYF, too.  I suggest reading the following for how to ask
technical questions:
          http://www.catb.org/~esr/faqs/smart-questions.html
          How To Ask Questions The Smart Way
          Eric Steven Raymond
and
          http://sscce.org/
          The SSCCE
          Short, Self Contained, Correct (Compilable), Example

Sincerely,

Gene Wirchenko

[toc] | [prev] | [next] | [standalone]

#2069

I think your problem is you don't know that all methods in interfaces
are implicitly public, therefore when you implement them, they must
remain public.
-- 
Roedy Green Canadian Mind Products http://mindprod.com
A new scientific truth does not triumph by convincing its opponents and making them see the light,
but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
~ Max Planck 1858-04-23 1947-10-04 

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.java.help

csiph-web