Question

Design a Geometry class with the following methods: A static method that accepts the radius of a circle and returns the area of the circle. Use the following formula: A r e a = π r 2 Use Math.PI for π and the radius of the circle for r. A static method that accepts the length and width of a rectangle and returns the area of the rectangle. Use the following formula: A r e a = L e n g t h × W i d t h A static method that accepts the length of a triangle’s base and the triangle’s height. The method should return the area of the triangle. Use the following formula: A r e a = B a s e × H e i g h t × 0.5 The methods should display an error message if negative values are used for the circle’s radius, the rectangle’s length or width, or the triangle’s base or height. Next, write a program to test the class, which displays the following menu and responds to the user’s selection: Geometry Calculator 1. Calculate the Area of a Circle 2. Calculate the Area of a Rectangle 3. Calculate the Area of a Triangle 4. Quit Enter your choice (1-4): Display an error message if the user enters a number outside the range of 1 through 4 when selecting an item from the menu.

Answer 1

Answer:

Geometry class

public static class Geometry {

   public static double areaOfCircle(double radius) {

       return Math.PI * radius * radius;

   }

   public static double areaOfRectangle(double length, double width) {

       return length * width;

   }

   public static double areaOfTriangle(double base, double h) {

       return base * h * 0.5;

   }

}

Main and user menu choice method\

public static void main(String[] args) {

   int choice; // The user's menu choice

   do {

       // Get the user's menu choice.

       choice = getMenu();

       if (choice == 1) {

           calculateCircleArea();

       } else if (choice == 2) {

           calculateRectangleArea();

       } else if (choice == 3) {

           calculateTriangleArea();

       } else if (choice == 4) {

           System.out.println("Thanks for calculating!");

       }

   } while (choice != 4);

}

public static int getMenu() {

   int userChoice;

   // keyboard input

   Scanner keyboard = new Scanner(System.in);

   // Display the menu.

   System.out.println("Geometry Calculator\n");

   System.out.println("1. Calculate the Area of a Circle");

   System.out.println("2. Calculate the Area of a Rectangle");

   System.out.println("3. Calculate the Area of a Triangle");

   System.out.println("4. Quit\n");

   System.out.print("Enter your choice (1-4) : ");

   // get input from user

   userChoice = keyboard.nextInt();

   // validate input

   while (userChoice < 1 || userChoice > 4) {

       System.out.print("Please enter a valid range: 1, 2, 3, or 4: ");

       userChoice = keyboard.nextInt();

   }

   return userChoice;

}

Calculate Circle Area

public static void calculateCircleArea() {

   double radius;

   // Get input from user

   Scanner keyboard = new Scanner(System.in);

   System.out.print("What is the circle's radius? ");

   radius = keyboard.nextDouble();

   // Display output

   System.out.println("The circle's area is "

           + Geometry.areaOfCircle(radius));

}

Calculate Rectangle Area

public static void calculateRectangleArea() {

   double length;

   double width;

   // Get input from user

   Scanner keyboard = new Scanner(System.in);

   // Get length

   System.out.print("Enter length? ");

   length = keyboard.nextDouble();

   // Get width

   System.out.print("Enter width? ");

   width = keyboard.nextDouble();

   // Display output

   System.out.println("The rectangle's area is "

           + Geometry.areaOfRectangle(length, width));

}

Calculate Triangle Area

public static void calculateTriangleArea() {

   double base;

   double height;

   // Get input from user

   Scanner keyboard = new Scanner(System.in);

   // Get the base

   System.out.print("Enter length of the triangle's base? ");

   base = keyboard.nextDouble();

   // Get the height

   System.out.print("Enter triangle's height? ");

   height = keyboard.nextDouble();

   // Display the triangle's area.

   System.out.println("The triangle's area is "

           + Geometry.areaOfTriangle(base, height));

}

Output

Geometry Calculator

1. Calculate the Area of a Circle

2. Calculate the Area of a Rectangle

3. Calculate the Area of a Triangle

4. Quit

Enter your choice (1-4) : 1

What is the circle's radius? 10

The circle's area is 314.1592653589793

Geometry Calculator

1. Calculate the Area of a Circle

2. Calculate the Area of a Rectangle

3. Calculate the Area of a Triangle

4. Quit

Enter your choice (1-4) : 2

Enter length? 10

Enter width? 10

The rectangle's area is 100.0

Geometry Calculator

1. Calculate the Area of a Circle

2. Calculate the Area of a Rectangle

3. Calculate the Area of a Triangle

4. Quit

Enter your choice (1-4) : 3

Enter length of the triangle's base? 10

Enter triangle's height? 10

The triangle's area is 50.0

Geometry Calculator

1. Calculate the Area of a Circle

2. Calculate the Area of a Rectangle

3. Calculate the Area of a Triangle

4. Quit

Enter your choice (1-4) : 4

Thanks for calculating!