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Question, reference, package

Chandra Bhatt
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Joined: Feb 28, 2007
Posts: 1707


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 ]

cmbhatt
swarna dasa
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Joined: Mar 15, 2007
Posts: 108
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.
Keith Lynn
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Joined: Feb 07, 2005
Posts: 2367
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
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Joined: Mar 15, 2007
Posts: 108
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

Joined: Feb 28, 2007
Posts: 1707
Thanks Swarna and Keith for your prompt reply.
It helped me to get the question correctly.



Thanks,
 
It is sorta covered in the JavaRanch Style Guide.
 
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