Question

I have given you a piece of code to test that your circle class works correctly. Add your circle class to the code.

public class Lab2Num1 {

public static class Circle
{ private double radius;
//your code goes here
  
//provide default constructor, constructor with one parameter, area, and circumference
  
}
public static void main(String[] args) {

Circle c = new Circle(1.5);


System.out.printf("The circumference of a circle of radius " + c.getRadius()+ " is %5.2f\n", c.circumference());
System.out.printf("The area of a circle of radius " +c.getRadius()+ " is %5.2f\n", c.area());
  
c.setRadius(5.0);
  
System.out.printf("The circumference of a circle of radius " + c.getRadius() + " is %5.2f\n", c.circumference());
System.out.printf("The area of a circle of radius " + c.getRadius() + " is %5.2f\n", c.area());
}//end main

}

Answer 1

Please find the code below:

Lab2Num1.java

package classes7;

public class Lab2Num1 {

   public static class Circle{

       private double radius;
       //your code goes here

       //provide default constructor, constructor with one parameter, area, and circumference
       public Circle() {
           radius = 0;
       }

       public Circle(double d) {
           radius = d;
       }

       public double getRadius() {
           return radius;
       }

       public void setRadius(double radius) {
           this.radius = radius;
       }

       public double circumference() {
           return 2*Math.PI*radius;
       }

       public double area() {
           return Math.PI*radius*radius;
       }

   }
   public static void main(String[] args) {

       Circle c = new Circle(1.5);

       System.out.printf("The circumference of a circle of radius " + c.getRadius()+ " is %5.2f\n", c.circumference());
       System.out.printf("The area of a circle of radius " +c.getRadius()+ " is %5.2f\n", c.area());

       c.setRadius(5.0);

       System.out.printf("The circumference of a circle of radius " + c.getRadius() + " is %5.2f\n", c.circumference());
       System.out.printf("The area of a circle of radius " + c.getRadius() + " is %5.2f\n", c.area());
   }//end main

}

output:

Quick Access 6 . Java EE 'Java * Debug 'Java Brows @ Console X * B 1 R 9 - D o <terminated > Lab2Num1 [Java Application) C:\Program FilesVava jdk1.8.0_121\jre\bin\javaw.exe (Mar 23, 2 The circumference of a circle of radius 1.5 is 9.42 The area of a circle of radius 1.5 is 7.07 The circumference of a circle of radius 5.0 is 31.42 The area of a circle of radius 5.0 is 78.54