Given the following UML is for a private member is for a p

Given the following UML (- is for a private member, + is for a public member, and underline is for a static member). The radius of this Circle object The number of Circle objects created Default Construct (initializes radius to 1 and update the numberOfObjects) Constructs a Circle object with radius (print error message if radius

Solution

public class Circle {

   private double radius;
   private static int numberOfObjects;

   public Circle() {
       // TODO Auto-generated constructor stub
       this.radius = 1;
       this.numberOfObjects++;
   }

   /**
   * @param radius
   * @param numberOfObjects
   */
   public Circle(double radius) {
       if (radius < 0) {
           System.out.println(\"Invalid radius\");
       } else {
           this.radius = radius;
           this.numberOfObjects++;
       }
   }

   /**
   * @return the radius
   */
   public double getRadius() {
       return radius;
   }

   /**
   * @param radius
   * the radius to set
   */
   public void setRadius(double radius) {
       if (radius < 0) {
           System.out.println(\"Invalid radius\");
       } else {
           this.radius = radius;
       }

   }

   /**
   * @return the numberOfObjects
   */
   public static int getNumberOfObjects() {
       return numberOfObjects;
   }

   /**
   * @return
   */
   public double getArea() {
       return Math.PI * this.radius * this.radius;
   }

   /*
   * (non-Javadoc)
   *
   * @see java.lang.Object#toString()
   */
   @Override
   public String toString() {
       return \"Circle [radius=\" + radius + \"]\";
   }

}

public class lastname_exam2 {

   public static void main(String[] args) {

       Circle circle1 = new Circle();
       System.out.println(\"Circle object with no argument constructor :\"
               + circle1.toString());
       System.out.println(\"Number of circle objects created : \"
               + Circle.getNumberOfObjects());

       Circle circle2 = new Circle(2);
       System.out.println(\"Circle object with argument constructor :\"
               + circle2.toString());
       System.out.println(\"Area :\" + circle2.getArea());
       System.out.println(\"Number of circle objects created : \"
               + Circle.getNumberOfObjects());

       circle1.setRadius(3);
       System.out.println(\"set Radius 3 for circle object:\"
               + circle1.toString());

   }
}

OUTPUT:

Circle object with no argument constructor :Circle [radius=1.0]
Number of circle objects created : 1
Circle object with argument constructor :Circle [radius=2.0]
Area :12.566370614359172
Number of circle objects created : 2
set Radius 3 for circle object:Circle [radius=3.0]