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Generic ? extends

 
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at line #2:
Why is it incompatible type? Integer extends Number is correct, isn't it?
and
Why compiler is checking LHS type, not RHS type (the actual object)?

thanks all

 
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From K & B, p. 596 & 583:


You cannot use wildcard notation in the object creation ... the type of the variable declaration must match the type you pass to the actual object type.

 
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? extends Number can store not only Integer, but also Long, Double etc.

So if the compiler is allowing
for(Integer n: type)

then it will fail at run time if the object reference variable points to Long or Double.
So inorder to avoid this situation , compiler is showing the error as incompatible types.
 
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