9.4.2

Overloading

INTERFACES

However, one of the inherited methods must be return-type-substitutable for every other inherited method; otherwise, a compile-time error occurs. (The throws clauses do not cause errors in this case.)

There might be several paths by which the same method declaration is inherited from an interface. This fact causes no difficulty and never, of itself, results in a compile-time error.

9.4.2 Overloading

If two methods of an interface (whether both declared in the same interface, or both inherited by an interface, or one declared and one inherited) have the same name but different signatures that are not override-equivalent (§8.4.2), then the 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.

Example 9.4.2-1. Overloading an abstract Method Declaration

interface PointInterface { void move(int dx, int dy);

}

interface RealPointInterface extends PointInterface { void move(float dx, float dy);

void move(double dx, double dy);

}

Here, the method named move is overloaded in interface RealPointInterface with three different signatures, two of them declared and one inherited. Any non-abstract class that implements interface RealPointInterface must provide implementations of all three method signatures.

9.5 Member Type Declarations

Interfaces may contain member type declarations (§8.5).

A member type declaration in an interface is implicitly static and public. It is permitted to redundantly specify either or both of these modifiers.

It is a compile-time error if the same modifier appears more than once in a member type declaration in an interface.

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