Java program to find diameter, circumference and area of circle













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Write a Java program to input radius of a circle from user and find diameter, circumference and area of the circle. How to calculate diameter, circumference and area of a circle whose radius is given by user in Java programming. Logic to find diameter, circumference and area of a circle in Java.








Required knowledge

Arithmetic operators, Data types, Defining constants, Basic input/output


Properties of circle

Diameter, circumference and area of a circle formula is given by -


Circle formulas

Where r is radius of the circle.


Logic to find diameter, circumference and area of circle

Below is the step by step descriptive logic to find diameter, circumference and area of a circle -

  1. Input radius of circle from user. Store it in a variable say radius.

  2. Apply the formulas to calculate diameter, circumference and area. Use diameter = 2 * radius, circumference = 2 * 3.14 * radius and area = 3.14 * radius * radius.

  3. Print all resultant value diameter, circumference and area.


Program to find diameter, circumference and area of circle

/**
 * Java program to calculate diameter, circumference and area of circle
 */

import java.util.Scanner;

class Test
{
public static void main(String args[])
{
    double radius, diameter, circumference, area;
    Scanner op=new Scanner(System.in);
    /*
     * Input radius of circle from user
     */
    System.out.print("Enter radius of circle: ");
    radius=op.nextDouble();

    /*
     * Calculate diameter, circumference and area
     */
    diameter = 2 * radius;
    circumference = 2 * 3.14 * radius;
    area = 3.14 * (radius * radius);

    /*
     * Print all results
     */
    System.out.println("Diameter of circle = "+diameter+" units ");
    System.out.println("Circumference of circle = "+circumference+" units ");
    System.out.println("Area of circle = "+area+" sq. units ");
    }
}




Output:

Enter radius of circle: 5
Diameter of circle = 10.0 units
Circumference of circle = 31.400000000000002 units
Area of circle = 78.5 sq. units

Program to find diameter, circumference and area of circle using PI constant
/**
 * Java program to calculate diameter, circumference and area of circle
 */
import java.util.Scanner;

class Test1
{
public static void main(String args[])
{
    double radius, diameter, circumference, area,M_PI;
    Scanner op=new Scanner(System.in);
    /*
     * Input radius of circle from user
     */
    System.out.print("Enter radius of circle: ");
    radius=op.nextDouble();
    M_PI=22/7;
    /*
     * Calculate diameter, circumference and area of circle
     */
    diameter = 2 * radius;
    circumference = 2 * M_PI * radius;
    area = M_PI * (radius * radius);

    /*
     * Print all results
     */
    System.out.println("Diameter of circle = "+diameter+" units");
    System.out.println("Circumference of circle = "+circumference+" units ");
    System.out.println("Area of circle = "+area+" sq. units ");
}
}



Output:

Enter radius of circle: 20
Diameter of circle = 40.0 units
Circumference of circle = 120.0 units
Area of circle = 1200.0 sq. units









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