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!
