Area and perimeter of a circle

The problem

Write program that displays the area (size of the surface) and perimeter (the distance around) of a circle that has a radius of 5.5:

perimeter = 2 * radius * p area = radius * radius * p

Breaking it down

To make the program more reusable and modular we will define two methods named calculateArea and calculatePerimeter. If the program was capturing user input we could pass a parameter to the method to calculate the values. Next from the main method we will call the method and set it to a local variable. Finally we will print the calculations to the console.

private static final double radius = 5.5;

public static void main(String[] args) {

    double perimeter = calculatePerimeter();
    double area = calculateArea();

    System.out.println("Perimeter = " + perimeter);
    System.out.println("Area = " + area);
}

private static double calculateArea() {
    double area = radius * radius * Math.PI;
    return area;
}

private static double calculatePerimeter() {
    double perimeter = 2 * radius * Math.PI;
    return perimeter;
}

Output

Perimeter = 34.55751918948772
Area = 95.03317777109125