Question

1. Complete the implementation of the Sphere class based on the Diagram below. Use the DecimalFormat class in Sphere.java to format your output in the toString method.

2. Then download the tester application SphereTester.java to test your Sphere class. Do not change SphereTester.java.

Sphere

private double radius      //radius of the sphere object private static int numSpheres   //static or class variable. All Sphere objects share it

public Sphere()    //constructor . Initialize Sphere objects’ instance variable radius to 0.0. It also increments numSpheres by 1.                                                                           public Sphere(double radiusInit) // overloaded constructor. Initialize Sphere objects’ instance variable radius. It also increments numSpheres by 1. public void setRadius(double aRadius) //sets Sphere objects’ instance variable radius public double getRadius()    // returns the value of the Sphere objects’ instance variable radius public double calculateVolume()    //computes and returns the volume of the Sphere object public double calculateArea()           //computes and returns the area of the Sphere object public double calculateDiameter()      //computes and returns the diameter of the Sphere object public static int getNumSpheres() //returns the number of sphere objects public String toString()     // returns a String representation of the Sphere object along with the                                                                                                                         // the volume and area with formatting.

Your output must look exactly as follow.

Basketball

----------

radius: 4.75   volume: 448.921    area: 283.529

numSpheres: 1

Eyeball

----------

radius: 0.5   volume: 0.524   area: 3.142

numSpheres: 2

Softball's radius: 0.0

Softball after setting radius to 18.4

------------------------------------

radius: 18.4   volume: 26094.085    area: 4254.47

numSpheres: 3

/**
 * 
 * 
 * Do not change the tester. 
 *
 */
public class SphereTester
{ 
//-----------------------------------------------------------------
//  Creates and exercises some Sphere objects.
//-----------------------------------------------------------------
   public static void main(String[] args)
   {
    
        
        Sphere basketBall = new Sphere(4.75);  //in inches
        System.out.println("Basketball\n----------\n" + basketBall);
        //println will implicitly/automaticlly call toString method of the Sphere object.
        
        Sphere eyeBall    = new Sphere(0.5);
        System.out.println("Eyeball\n----------\n"+eyeBall.toString()); //explicitly calling toString()
        
        Sphere softBall;          // 1. Declare a reference "softBall" to the Sphere object
        softBall = new Sphere(); //2. Create the object using new operation
   
        System.out.println("Softball's radius: " + softBall.getRadius() );
        
        softBall.setRadius(18.4);

        System.out.println("Softball after setting radius to " +softBall.getRadius()+"\n------------------------------------" );

        System.out.println(softBall);
        
        
    }
}

/*Basketball
----------
radius: 4.75   volume: 448.921    area: 283.529
numSpheres: 1

Eyeball
----------
radius: 0.5   volume: 0.524    area: 3.142
numSpheres: 2

Softball's radius: 0.0
Softball after setting radius to 18.4
------------------------------------
radius: 18.4   volume: 26094.085    area: 4254.47
numSpheres: 3

*/

Answer 1

JAVA PROGRAM :-

class Sphere {

private double radius; //radius of the sphere object
private static int numSpheres = 0; //static or class variable. All Sphere objects share it

//constructor . Initialize Sphere objects’ instance variable radius to 0.0. It also increments numSpheres by 1.
public Sphere(){
this.radius = 0.0;
numSpheres = numSpheres + 1;
}

// overloaded constructor. Initialize Sphere objects’ instance variable radius. It also increments numSpheres by 1.
public Sphere(double radiusInit){
this.radius = radiusInit;
numSpheres = numSpheres + 1;
}

//sets Sphere objects’ instance variable radius
public void setRadius(double aRadius){
this.radius = aRadius;
}

// returns the value of the Sphere objects’ instance variable radius
public double getRadius(){
return this.radius;
}

//computes and returns the volume of the Sphere object
public double calculateVolume(){
double temp;
temp = (double)4.0/3.0;
temp = temp * (22.0/7.0);
temp = temp * this.radius * this.radius * this.radius;
return temp;
}

//computes and returns the area of the Sphere object
public double calculateArea(){
double temp;
temp = (double)4.0;
temp = temp * (22.0/7.0);
temp = temp * this.radius * this.radius;
return temp;
}

//computes and returns the diameter of the Sphere object
public double calculateDiameter(){
return (2.0*this.radius);
}

//returns the number of sphere objects
public static int getNumSpheres(){
return numSpheres;
}

// returns a String representation of the Sphere object along with the
// the volume and area with formatting.
public String toString(){
String str1 = "The sphere with radius "+Double.toString(this.radius)+" with volume "+Double.toString(calculateVolume())+" and area "+Double.toString(calculateArea());
return str1;
}
}

public class SphereTester
{
//-----------------------------------------------------------------
// Creates and exercises some Sphere objects.
//-----------------------------------------------------------------
public static void main(String[] args)
{
  
  
Sphere basketBall = new Sphere(4.75); //in inches
System.out.println("Basketball\n----------\n" + basketBall);
//println will implicitly/automaticlly call toString method of the Sphere object.
  
Sphere eyeBall = new Sphere(0.5);
System.out.println("Eyeball\n----------\n"+eyeBall.toString()); //explicitly calling toString()
  
Sphere softBall; // 1. Declare a reference "softBall" to the Sphere object
softBall = new Sphere(); //2. Create the object using new operation

System.out.println("Softball's radius: " + softBall.getRadius() );
  
softBall.setRadius(18.4);

System.out.println("Softball after setting radius to " +softBall.getRadius()+"\n------------------------------------" );

System.out.println(softBall);
  
  
}
}

Output :-