# Area of Circle And Calculate Circumference

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You are here to learn area of circle and calculate circumference.

Decades ago we have seen and learnt area of circle in our school in geometry class.

I still remember the way how our geometry teacher explained the concept of area of circle using compass and measuring the radius using ruler.

Good’ol days… Now we will see area of a circle in java program.

#### example: Area of Circle And Calculate Circumference

// Area of circle is, area = pi * r * r where r is the radius of a circle

Also Read – Area of Rectangle Program in Java

```import java.io.BufferedReader;
import java.io.IOException;

public class AreaOfCircle
{
public static void main(String[] args)
{
System.out.println("Enter the radius of a Circle: ");
try
{
}
// To check whether invalid value was entered
catch(NumberFormatException nfe)
{
System.exit(0);
}
catch(IOException ioe)
{
System.out.println("IO Error: " + ioe);
System.exit(0);
}
System.out.println("Area of a circle is " + circleArea);
}
}```

Output:
Enter the radius of a Circle: 10
Area of a circle is 314.1592653589793

#### to calculate circumference: Area of Circle And Calculate Circumference

```import java.util.Scanner;

public class CircleCircumference
{
public static void main(String[] args)
{
// Here we are declaring Scanner class which could read from         console
Scanner sc = new Scanner(System.in);
double circumference = 0.0;
// Formula for calculating circumference of circle
// circumference = 2 * 22 / 7 * radius
circumference = 2 * Math.PI * radius; System.out.println("Circumference of circle is : " + circumference);
}
}```

Output:

Circumference of circle is : 31.41592653589793

#### to calculate area of circle using method

```import java.util.Scanner;

public class AreaOfCircleDemo
{
public static void main(String[] args)
{
double  area = calculateArea(radius);     System.out.println("The area of circle is : " + area);     sc.close();
}

static double calculateArea(double r)
{
return (22 * r * r) / 7;
}
}```

Output: