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Polymorphic method invocations apply only to overridden instance methods.

 
Greenhorn
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K & B say

"Polymorphic method invocations apply only to overridden instance methods." (last line P 153 in Ch. 2 Two Minute Drill).

My university notes say

"It is common for instances of unrelated classes to have the same message in their protocols, and instances of those classes may or may not respond differently to that message. Such messages are termed polymorphic messages"

Who is correct?

Thanks

W
 
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Originally posted by Wyn Riley:
..."It is common for instances of unrelated classes to have the same message in their protocols, and instances of those classes may or may not respond differently to that message. Such messages are termed polymorphic messages"...


I've never seen that definition before.
 
Greenhorn
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The notes seem a little confusing to me (I find the terminology a little strange), but the answer all kind of depends on your definition of polymorphism.

I did a search and this article had this to say:


Three distinct forms of polymorphism
From a practical programming viewpoint, polymorphism manifests itself in three distinct forms in Java:

* Method overloading
* Method overriding through inheritance
* Method overriding through the Java interface



The notes seem to be referring to polymorphism in the form of method overloading (sometimes called compile-time polymorphism), whereas K&B are talking about method overriding (sometimes called runtime polymorphism).

For your purposes, it's probably best to keep in mind K&B's usage.
 
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