Hi Sang,can u give me the link for downloading the workin example. Where is
the link of working codes
On Jan 7, 2013 1:30 AM, "Sang Shin" <[email protected]> wrote:
> On 1/6/2013 2:19 PM, Deepak A L wrote:
>
> Hi Joel/Sang,
> Can u plz provide the complete working example for the
> below
> Example 3--polymorphic behaviour.
>
>
> OK. The new hands-on lab has been uploaded. I ended up modifying
> interface code from
>
> public interface BookInterface extends ProductInterface{
> public String getPublisher();
> public void setPublisher(String publisher);
> public int getYearPublished();
> public void setYearPublished(int yearPublished);
> }
>
> to
>
> public interface BookInterface {
> public String getPublisher();
> public void setPublisher(String publisher);
> public int getYearPublished();
> public void setYearPublished(int yearPublished);
> }
>
> while the Book.java as it is as shown below
>
> public class Book extends Product implements BookInterface{
>
> private String publisher;
> private int yearPublished;
>
> /** Creates a new instance of Book */
> public Book(double regularPrice,
> String publisher,
> int yearPublished) {
> super(regularPrice);
> this.publisher = publisher;
> this.yearPublished = yearPublished;
> }
> ...
>
> This way, we are still showing Interrface-based (ProductInterface.java)
> polymorphism while removing the redundancy Joel has pointed out
> in his original question.
>
> -Sang
>
> -----
> Deepak
> On Jan 6, 2013 9:23 PM, "Sang Shin" <[email protected]> wrote:
>
>> On 1/5/2013 5:53 PM, Joel wrote:
>>
>> Hi Sang,
>>
>> In studying the Example 3 (Polymorphic behavior via Java Interface) in
>> the Polymorphism lab of Javase, there is an interface class defined as
>> follows:
>>
>> public interface BookInterface extends ProductInterface {
>> public String getPublisher();
>> public void setPublisher(String publisher);
>> public int getYearPublished();
>> public void setYearPublished(int yearPublished);
>> }
>>
>> Why does this class need to extend ProductInterface? I ask because
>> Product class already implements ProductInterface. So when you define the
>> Book class as:
>>
>> public class Book extends Product* implements BookInterface*{ ...}
>>
>> ...it seems as though the Book class inherits ProductInterface twice:
>> once from extending Product and again in the BookInterface implementation.
>>
>>
>> Your observation indeed is correct.
>>
>>
>> *I modified the BookInterface definition by removing extends
>> ProductInterface and the code runs fine without error.
>>
>> *So my questions are:
>> Is there a reason you extend BookInterface with ProductInterface? Or is
>> this simply superfluous coding?
>>
>>
>> The latter. :-) Apparently the only reason it also extends Product class
>> is
>> to use a constructor method of the Product class but it does not have
>> to as you pointed out. (The sample code actually uses this
>>
>> I also found there is some discrenpancy between the document and
>> the code sample, which I am in the process of cleaning up.
>>
>>
>> And why does the compiler not complain in Book class that it inherits
>> ProductInterface interface twice: once from Product and again from
>> BookInterface? Is it Ok to inherit the same abstract methods twice like
>> this?
>>
>>
>> Correct. This is a not compiler error.
>>
>> -Sang
>>
>>
>> Joel
>> --
>> You received this message because you are subscribed to the Google Groups
>> "JPassion.com: Java Programming" group.
>> To unsubscribe from this group, send email to
>> [email protected].
>> Visit this group at http://groups.google.com/group/jpassion_java?hl=en-US
>> .
>>
>>
>>
>>
>>
>> --
>> -------------------------------------------------------------------
>> Sang Shin, [email protected]
>> http://www.linkedin.com/in/javapassion (Linkedin)
>> http://twitter.com/javapassion (Tweeter)
>> Life is worth living... with Passion!
>>
>> Free Webinars: "Ruby on Rails", "MySQL", "Java EE 6", "Java Performance"
>> http://javapassion.com/webinars
>> ----------------------------------------------------------------------
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "JPassion.com: Java Programming" group.
>> To unsubscribe from this group, send email to
>> [email protected].
>> Visit this group at http://groups.google.com/group/jpassion_java?hl=en-US
>> .
>>
>>
>>
>
>
> --
> -------------------------------------------------------------------
> Sang Shin, [email protected]
> http://www.linkedin.com/in/javapassion (Linkedin)
> http://twitter.com/javapassion (Tweeter)
> Life is worth living... with Passion!
>
> Free Webinars: "Ruby on Rails", "MySQL", "Java EE 6", "Java Performance"
> http://javapassion.com/webinars
> ----------------------------------------------------------------------
>
>
--
You received this message because you are subscribed to the Google Groups
"JPassion.com: Java Programming" group.
To unsubscribe from this group, send email to
[email protected].
Visit this group at http://groups.google.com/group/jpassion_java?hl=en-US.
