Win a copy of Escape Velocity: Better Metrics for Agile Teams this week in the Agile and Other Processes forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Liutauras Vilda
  • Tim Cooke
  • Paul Clapham
  • Jeanne Boyarsky
Sheriffs:
  • Ron McLeod
  • Frank Carver
  • Junilu Lacar
Saloon Keepers:
  • Stephan van Hulst
  • Tim Moores
  • Tim Holloway
  • Al Hobbs
  • Carey Brown
Bartenders:
  • Piet Souris
  • Frits Walraven
  • fred rosenberger

Question, reference, package

 
Ranch Hand
Posts: 1710
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator


I feel it difficult to understand the things;
Is this something talking about what reference variable can be passed to the method?

Please help.


Source
Thanks,
[ May 01, 2007: Message edited by: Chandra Bhatt ]
 
Ranch Hand
Posts: 108
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
A and B are fine for obvious reasons
C causes compiler error
D is fine given that all we do is assign it to the lastEvent.
However if one would try to use it, you would get a NullPointerException.

Given the code:- D should be fine as lastEvent is not used.
 
Ranch Hand
Posts: 2412
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
The point of this question is that if a method expects a reference parameter of type A, then you can send any reference parameter which has the "is a" relationship with A.

One thing this means is that you cannot send a superclass of type A to the method.
 
swarna dasa
Ranch Hand
Posts: 108
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Man!!! you edit your posts in fraction of a second... thats fast..

Yup it deals with inheritance, the kind of reference variables used.

So Reference of the Base class or subclasses would be fine.
 
Chandra Bhatt
Ranch Hand
Posts: 1710
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Thanks Swarna and Keith for your prompt reply.
It helped me to get the question correctly.



Thanks,
 
So it takes a day for light to pass through this glass? So this was yesterday's tiny ad?
Garden Master Course kickstarter
https://coderanch.com/t/754577/Garden-Master-kickstarter
reply
    Bookmark Topic Watch Topic
  • New Topic