Name: gb36485 Date: 04/16/99


This thows an error

C:\WINDOWS\DESKTOP\Projects\b>type xx.java
class A {A check() { return null; }}
class B extends A { B check() { return null; }}
C:\WINDOWS\DESKTOP\Projects\b>javac xx.java
xx.java:6: The method B check() declared in class B
cannot override the method of the same signature
declared in class A. They must have the same
return type.

  B check() { return null; }
    ^

This is correct according to the jls 8.4.6.3. However,
I think that when overriding a method, it ought to be
permissable to narrow the type of the return value.
In the fragment above, an object of class B is always
going also to be of type A, as A is a subclass of A.
This is in the same spirit as an overriding method
being able to specify that it does not throw errors
that a the superclass may. Restricting a subclass
is always ok.
(Review ID: 52365)
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