Implement a class Balloon that models a spherical balloon that is being filled with air. The constructor constructs an empty balloon. Supply these methods: void addAir(double amount) adds the given amount of air.
double getVolume() gets the current volume.
double getSurfaceArea() gets the current surface area.
double getRadius() gets the current radius.

Supply a BalloonTester class that constructs a balloon, adds 100cm^3 of air, tests the three accessor methods, adds another 100cm3 of air, and tests the accessor methods again.

Here is the Balloon class:

public class Balloon {  //class name

private double volume;  //private member variable of type double of class Balloon to store the volume

public Balloon()  {  //constructor of Balloon

 volume = 0;  }  //constructs an empty balloon by setting value of volume to 0 initially

void addAir(double amount)  {  //method addAir that takes double type variable amount as parameter and adds given amount of air

 volume = volume + amount;  }  //adds amount to volume

double getVolume()  {  //accessor method to get volume

 return volume;  }  //returns the current volume

double getSurfaceArea()  {  //accessor method to get current surface area

 return volume * 3 / this.getRadius();  }  //computes and returns the surface area

double getRadius()  {  //accessor method to get the current radius

 return Math.pow(volume / ((4 * Math.PI) / 3), 1.0/3);  }  } //formula to compute the radius

Explanation:

Here is the BalloonTester class

public class BalloonTester {  //class name

  public static void main(String[] args)    { //start of main method

      Balloon balloon = new Balloon();  //creates an object of Balloon class

      balloon.addAir(100);  //calls addAir method using object balloon and passes value of 100 to it

      System.out.println("Volume "+balloon.getVolume());  //displays the value of volume by getting value of volume by calling getVolume method using the balloon object

      System.out.println("Surface area "+balloon.getSurfaceArea());  //displays the surface area by calling getSurfaceArea method using the balloon object

             System.out.println("Radius "+balloon.getRadius());   //displays the value of radius by calling getRadius method using the balloon object

     balloon.addAir(100);  //adds another 100 cm3 of air using addAir method

       System.out.println("Volume "+balloon.getVolume());  //displays the value of volume by getting value of volume by calling getVolume method using the balloon object

      System.out.println("Surface area "+balloon.getSurfaceArea());  //displays the surface area by calling getSurfaceArea method using the balloon object

             System.out.println("Radius "+balloon.getRadius());    }  }  //displays the value of radius by calling getRadius method using the balloon object

//The screenshot of the output is attached.