The Java Language Specification, Third Edition

CLASSES Inheritance, Overriding, and Hiding 8.4.8
A compile-time error occurs if an instance method overrides a static
method.
In this respect, overriding of methods differs from hiding of fields (§8.3), for
it is permissible for an instance variable to hide a static variable.
An overridden method can be accessed by using a method invocation expression
(§15.12) that contains the keyword super. Note that a qualified name or a
cast to a superclass type is not effective in attempting to access an overridden
method; in this respect, overriding of methods differs from hiding of fields. See
§15.12.4.9 for discussion and examples of this point.
The presence or absence of the strictfp modifier has absolutely no effect on
the rules for overriding methods and implementing abstract methods. For example,
it is permitted for a method that is not FP-strict to override an FP-strict
method and it is permitted for an FP-strict method to override a method that is not
FP-strict.
8.4.8.2 Hiding (by Class Methods)
If a class declares a static method m, then the declaration m is said to hide any
method m’, where the signature of m is a subsignature (§8.4.2) of the signature of
m’, in the superclasses and superinterfaces of the class that would otherwise be
accessible to code in the class. A compile-time error occurs if a static method
hides an instance method.
In this respect, hiding of methods differs from hiding of fields (§8.3), for it is
permissible for a static variable to hide an instance variable. Hiding is also distinct
from shadowing (§6.3.1) and obscuring (§6.3.2).
A hidden method can be accessed by using a qualified name or by using a
method invocation expression (§15.12) that contains the keyword super or a cast
to a superclass type. In this respect, hiding of methods is similar to hiding of
fields.
DRAFT
8.4.8.3 Requirements in Overriding and Hiding
If a method declaration d1 with return type R1 overrides or hides the declaration of
another method d2 with return type R2, then d1 must be return-type substitutable
for d2, or a compile-time error occurs. Furthermore, if R1 is not a subtype of R2,
an unchecked warning must be issued (unless suppressed (§9.6.1.5)).
A method declaration must not have a throws clause that conflicts (§8.4.6)
with that of any method that it overrides or hides; otherwise, a compile-time error
occurs.
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