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changing reference types

Neha Mittal

Joined: Dec 05, 2008
Posts: 10
What does this mean -> "Although a reference variable's type can't be changed, it can be used to refer to an object whose type is a subtype of its own" ?

Dreams are not which you see when you are asleep. Dreams are that that do not let you sleep..
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 42020
You can have a reference to a Vehicle. You can use that reference to point to a Car object or a Bus object.
Aum Tao
Ranch Hand

Joined: Feb 14, 2006
Posts: 210
This is referring to inheritance. Consider the following example:

Taking your case, the Animal reference can be assigned to the Dog object, since it satisfies the IS A relationship. However, this fails for the second assignment since Shape doesn't extend Animal. Moreover, it shouldn't since they are not logically related.

SCJP 1.4 85%
I agree. Here's the link:
subject: changing reference types