The Java Language Specification, Third Edition

8.4.10 Examples of Method Declarations CLASSES
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time error. There is no required relationship between the return types or between
the throws clauses of two methods with the same name, unless their signatures
are override-equivalent.
Methods are overridden on a signature-by-signature basis.
If, for example, a class declares two public methods with the same name,
and a subclass overrides one of them, the subclass still inherits the other method.
When a method is invoked (§15.12), the number of actual arguments (and any
explicit type arguments) and the compile-time types of the arguments are used, at
compile time, to determine the signature of the method that will be invoked
(§15.12.2). If the method that is to be invoked is an instance method, the actual
method to be invoked will be determined at run time, using dynamic method
lookup (§15.12.4).
8.4.10 Examples of Method Declarations
The following examples illustrate some (possibly subtle) points about method
declarations.
8.4.10.1 Example: Overriding
In the example:
class Point {
int x = 0, y = 0;
void move(int dx, int dy) { x += dx; y += dy; }
}
class SlowPoint extends Point {
int xLimit, yLimit;
void move(int dx, int dy) {
super.move(limit(dx, xLimit), limit(dy, yLimit));
}
static int limit(int d, int limit) {
return d > limit ? limit : d < -limit ? -limit : d;
}
}
the class SlowPoint overrides the declarations of method move of class Point
with its own move method, which limits the distance that the point can move on
each invocation of the method. When the move method is invoked for an instance
of class SlowPoint, the overriding definition in class SlowPoint will always be
DRAFT