The Java Language Specification, Third Edition

INTERFACES Examples of Abstract Method Declarations 9.4.3
method name is said to be overloaded. This fact causes no difficulty and never of
itself results in a compile-time error. There is no required relationship between the
return types or between the throws clauses of two methods with the same name
but different signatures that are not override-equivalent.
9.4.3 Examples of Abstract Method Declarations
The following examples illustrate some (possibly subtle) points about abstract
method declarations.
9.4.3.1 Example: Overriding
Methods declared in interfaces are abstract and thus contain no implementation.
About all that can be accomplished by an overriding method declaration, other
than to affirm a method signature, is to refine the return type or to restrict the
exceptions that might be thrown by an implementation of the method. Here is a
variation of the example shown in (§8.4.3.1):
class BufferEmpty extends Exception {
BufferEmpty() { super(); }
BufferEmpty(String s) { super(s); }
}
class BufferException extends Exception {
BufferException() { super(); }
BufferException(String s) { super(s); }
}
public interface Buffer {
char get() throws BufferEmpty, BufferException;
}
public interface InfiniteBuffer extends Buffer {
char get() throws BufferException;// override
}
DRAFT
9.4.3.2 Example: Overloading
In the example code:
interface PointInterface {
void move(int dx, int dy);
}
interface RealPointInterface extends PointInterface {
void move(float dx, float dy);
void move(double dx, double dy);
}
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