Interfaces and Polymorphism - Java Concepts - page 552

23 System.out.println( "Expected:
java.awt.Rectangle[
24 x=10,y=20,width=30,height=40]" );
25 }
26 }

401
402

ch09/measure2/Measurer.java

1 /**
2 Describes any class whose objects can measure other objects.
3 */
4 public interface Measurer
5 {
6 /**
7 Computes the measure of an object.
8 @param anObject the object to be measured
9 @return the measure
10 */
11 double measure(Object anObject);
12 }

ch09/measure2/RectangleMeasurer.java

1 import java.awt.Rectangle;
2
3 /**
4 Objects of this class measure rectangles by area.
5 */
6 public class RectangleMeasurer implements
Measurer
7 {
8 public double measure(Object anObject)
9 {
10 Rectangle aRectangle = (Rectangle)
anObject;
11 double area = aRectangle.getWidth() *
aRectangle.getHeight();
12 return area;
13 }
14 }