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new Circle()
SR5. Figure 3.5. contains a class Coordinates . Evaluate the expression shown
below. When executing the constructor call or evaluating the call to function
String , step over the calls, i.e. do the call as an indivisible action in terms of the
specification of the method.
( new Coordinates(5, 6)).toString()
Consider these three assignment statements:
Coordinates x= new Coordinates(5, 6);
Coordinates y= new Coordinates(5, 6);
Coordinates z= y;
What is the value of the expression x==y ? Of x==z ? Of y==z ? Of x==x ?
Answers to Self-review exercises
SR1. String s; Employee emp;
SR2. (1) create a folder of class C , (2) execute the constructor call C( args ); ,
and (3) yield the name of the new folder as the value.
/** An instance is a circle with a center and a radius */
public class Circle {
/** The circle has center cent and radius rad */
public Coordinates center;
public int radius;
/** Constructor: a circle with center (x, y) and radius r */
public Circle ( int x, int y, int r) {
center= new Coordinates(x, y);
radius= r;
/** = the center of the circle */
public Coordinates center() { return center; }
/** = the radius of the circle */
public int radius() { return radius; }
/** = the diameter of this circle */
public int diameter() { return 2*radius; }
/** = the area of this circle */
public double area() { return Math.PI * radius * radius; }
Figure 3.6:
Class Circle
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