Question

Write a Java program such that it consists of 2 classes:

1. a class that serves as the driver (contains main())

2. a class that contains multiple private methods that compute and display

a. area of a triangle (need base and height)

b area of a circle (use named constant for PI) (need radius)

c. area of rectangle (width and length)

d. area of a square (side)

e. surface area of a solid cylinder (height and radius of base)

N.B. You will also need an accessor public method (interface) that is called from the driver. This method should:

a. Display a menu of options to the user. (Suggest use switch statement)

b. Accept input from the user (keyboard) representing parameter values needed.

c. Invoke other [private] methods in the class to perform the necessary area computations

Add comments throughout your code as you deem appropriate.

Answer 1

shape.java :

//import package
import java.util.Scanner;

//Java class
public class shape {
   // Object of Scanner class
   Scanner sc = new Scanner(System.in);

//private methods that compute and display area of a triangle
   private void triangleArea(double base, double height) {
       // compute and print area of triangle
       System.out.println(
               "Area of triangle with base " + base + " and height " + height + " is : " + (base * height) / 2);
   }

   // private methods that compute and display area of a circle
   private void circleArea(double radius) {
       // compute and print area of circle
       System.out.println("Area of circle with radius " + radius + " is : " + (Math.PI * radius * radius));
   }

   // private methods that compute and display area of rectangle (width and length)
   private void rectangleArea(double width, double length) {
       // compute and print area of rectangle
       System.out.println(
               "Area of rectangle with width " + width + " and length " + length + " is : " + (width * length));
   }

   // private methods that compute and display area of a square (side)
   private void squareArea(double side) {
       // compute and print area of square
       System.out.println("Area of square with side " + side + " is : " + (side * side));
   }

   // private methods that compute and display surface area of a solid cylinder
   // (height and radius of base)
   private void cylinderSurafceArea(double height, double radius) {
       // compute and print surface area of a solid cylinder (height and radius of
       // base)
       System.out.println("Area of solid cylinder with height " + height + " and radius " + radius + " is : "
               + (2.0 * Math.PI * radius * height + 2.0 * Math.PI * radius * radius));
   }

   // This method will display menu to the user
   public void displayMenu() {
       System.out.println("Select Shape to calculate area : ");
       System.out.println("1.Area of a triangle");
       System.out.println("2.Area of a circle ");
       System.out.println("3.Area of a rectangle ");
       System.out.println("4.Area of a square ");
       System.out.println("5.Area of a solid cylinder ");
       // asking user choice
       System.out.print("Select choice : ");
       // reading choice
       int choice = sc.nextInt();
       // using switch statement
       switch (choice) {
       case 1:// when area of triangle is selected
               // asking user base
           System.out.print("Enter base : ");
           double base = sc.nextDouble();// reading base
           // asking user height
           System.out.print("Enter height : ");
           double height = sc.nextDouble();// reading height
           // call method and pass base and height
           triangleArea(base, height);
           break;
       case 2:// when area of circle is selected
               // asking user radius
           System.out.print("Enter radius : ");
           double radius = sc.nextDouble();// reading radius
           // call method and pass radius
           circleArea(radius);
           break;
       case 3:// when area of rectangle is selected
               // asking user width
           System.out.print("Enter width : ");
           double width = sc.nextDouble();// reading width
           // asking user length
           System.out.print("Enter length : ");
           double length = sc.nextDouble();// reading length
           // call method and pass width and length
           rectangleArea(width, length);
           break;
       case 4:// when area of square is selected
               // asking user side
           System.out.print("Enter side : ");
           double side = sc.nextDouble();// reading side
           // call method and pass side
           squareArea(side);
           break;
       case 5:// when area of solid cylinder is selected
               // asking user width
           System.out.print("Enter height : ");
           double height1 = sc.nextDouble();// reading height
           // asking user radius of base
           System.out.print("Enter radius of base : ");
           double radiusOfBase = sc.nextDouble();// reading radius of base
           // call method and pass height and radius
           cylinderSurafceArea(height1, radiusOfBase);
           break;
       default ://when invalid choice is entered
           System.out.println("Enter valid choice.");

       }
   }

}
***********************************

shapeTest.java :

//import package
import java.util.*;

//Java class
public class shapeTest {
   // main() method
   public static void main(String[] args) {
      
       // creating obejct of Shape class
       shape s = new shape();
       // calling method to display menu
       s.displayMenu();
      

   }

}
=========================================

Screen showing area of triangle :

Screen showing area of side :