Question

Imagine that you have access to a class named MyCircle that has void setRadius(double r) and double getRadius() methods. Write a static method that accepts a MyCircle array. The method should accomplish two goals: it should return the average of the radius’s for all MyCircles that have a positive radius, and for any MyCircles that have a negative radius it should set the radius to 0.

Answer 1

Code for the method described in the question in java:

public static double averageRadius(MyCircle[] myCircles) {

       double sum = 0;

       for (MyCircle myCircle: myCircles) {

           if(myCircle.getRadius() < 0) myCircle.setRadius(0);

           sum += myCircle.getRadius();

       }

       return sum / myCircles.length;

   }

And the complete program:

import java.util.Random;

public class MyCircle {

   private double radius;

   public double getRadius() {

       return radius;

   }

   public void setRadius(double radius) {

       this.radius = radius;

   }

   public static double averageRadius(MyCircle[] myCircles) {

       double sum = 0;

       for (MyCircle myCircle: myCircles) {

           if(myCircle.getRadius() < 0) myCircle.setRadius(0);

           sum += myCircle.getRadius();

       }

       return sum / myCircles.length;

   }

   public static void main(String[] args) {

       Random random = new Random();

       int N = 10;

       MyCircle[] myCircles = new MyCircle[N];

       for (int i = 0; i < myCircles.length; i++) {

           myCircles[i] = new MyCircle();

           myCircles[i].setRadius(random.nextInt(100));

           System.out.printf("Created MyCircle %d with radius %.2f \n", i, myCircles[i].getRadius());

       }

       System.out.printf("\nAverage radius of %d circles is %.2f \n", N, MyCircle.averageRadius(myCircles));

   }

}

The output was:

Created MyCircle 0 with radius 76.00

Created MyCircle 1 with radius 86.00

Created MyCircle 2 with radius 38.00

Created MyCircle 3 with radius 4.00

Created MyCircle 4 with radius 8.00

Created MyCircle 5 with radius 39.00

Created MyCircle 6 with radius 77.00

Created MyCircle 7 with radius 78.00

Created MyCircle 8 with radius 39.00

Created MyCircle 9 with radius 46.00

Average radius of 10 circles is 49.10