8.1.4

Superinterfaces

CLASSES

In the example:

public interface Colorable {

void setColor(int color);

int getColor();

}

public interface Paintable extends Colorable {

int MATTE = 0, GLOSSY = 1;

void setFinish(int finish);

int getFinish();

}

class Point { int x, y; }

class ColoredPoint extends Point implements Colorable {

int color;

public void setColor(int color) { this.color = color; }

public int getColor() { return color; }

}

class PaintedPoint extends ColoredPoint implements Paintable

{

int finish;

public void setFinish(int finish) {

this.finish = finish;

}

public int getFinish() { return finish; }

}

the relationships are as follows:

The interface

Paintable

 is a superinterface of class

PaintedPoint

.

The interface

Colorable

 is a superinterface of class

ColoredPoint

 and of

class

PaintedPoint

.

The interface

Paintable

 is a subinterface of the interface

Colorable

, and

Colorable

 is a superinterface of

Paintable

,

a

s defined in  9.1.3.

A class can have a superinterface in more than one way. In this example, the class

PaintedPoint

 has

Colorable

 as a superinterface both because it is a superinter 

face of

ColoredPoint

 and because it is a superinterface of

Paintable

.

Unless the class being declared is

abstract

, the declarations of the methods

defined in each direct superinterface must be implemented either by a declaration

in this class or by an existing method declaration inherited from the direct super 

class, because a class that is not

abstract

 is not permitted to have

abstract

methods ( 8.1.2.1).

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