The Java Language Specification, Third Edition

8.4.3 Method Modifiers CLASSES
214
Two method signatures m1 and m2 are override-equivalent iff either m1 is a subsignature
of m2 or m2 is a subsignature of m1.
The example:
class Point implements Move {
int x, y;
abstract void move(int dx, int dy);
void move(int dx, int dy) { x += dx; y += dy; }
}
causes a compile-time error because it declares two move methods with the same
(and hence, override-equivalent) signature. This is an error even though one of the
declarations is abstract.
8.4.3 Method Modifiers
MethodModifiers:
MethodModifier
MethodModifiers MethodModifier
MethodModifier: one of
Annotation public protected private abstract static
final synchronized native strictfp
The access modifiers public, protected, and private are discussed in
§6.6. A compile-time error occurs if the same modifier appears more than once in
a method declaration, or if a method declaration has more than one of the access
modifiers public, protected, and private. A compile-time error occurs if a
method declaration that contains the keyword abstract also contains any one of
the keywords private, static, final, native, strictfp,orsynchronized.A
compile-time error occurs if a method declaration that contains the keyword
native also contains strictfp.
If an annotation a on a method declaration corresponds to an annotation type
T, and T has a (meta-)annotation m that corresponds to annotation.Target, then
m must have an element whose value is annotation.ElementType.METHOD, ora
compile-time error occurs. Annotations are discussed further in §9.7.
If two or more method modifiers appear in a method declaration, it is customary,
though not required, that they appear in the order consistent with that shown
above in the production for MethodModifier.
8.4.3.1 abstract Methods
DRAFT
An abstract method declaration introduces the method as a member, providing
its signature (§8.4.2), return type, and throws clause (if any), but does not provide