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Object Reference Conversion

 
Brian Nguyen
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Hello,
Could some one please explain to me the following rules of object reference conversion:
- If Old Type is an interface and New Type is a class, then the New Type must be Object.
- If Old Type is an array and New Type is a class, then New Type must be Object.
Thank you very much.
Brian
 
Corey McGlone
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Look at the JLS, §5.5 Casting Conversion. It outlines all of the details about casting conversions. If you have any more questions, just let me know.
Corey
 
Anthony Villanueva
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Yes on both counts.


The new object reference must be a supertype of the old object reference. No class can be considered a supertype of an interface except for Object.
(If we have interface/classes A and B, and B is a subclass or subinterface of A either directly or though some intervening "layers" of classes/interfaces, then A is a supertype of B.)
Object arrays, and arrays of primitives are considered of type Object.
[ June 27, 2002: Message edited by: Anthony Villanueva ]
 
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