## How to find the perimeter of a circle in Java:

In this post, we will learn how to find the *perimeter* of a *circle* in *Java*. If you know the formula to find the *perimeter* of a circle, then you can do it easily by using a program.

Let’s take a look at the below circle image:

The white line is the *radius* of the circle. It is the distance starts from the center of a circle to its edge.

To find the *perimeter*, we can use the below formula:

`2 * π * radius`

Here, *π* is a mathematical constant. It is the ratio of *circumference* to the *diameter* of a circle. It is equal to *22/7*. We can use *22/7* or we can use it from a class where it is already defined.

So, if we get the *radius* as input from a user, we can calculate the *circumference*.

### Java program:

Below is the complete program:

```
import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
double radius, perimeter;
System.out.println("Enter the radius of the circle: ");
radius = scanner.nextDouble();
perimeter = 2 * Math.PI * radius;
System.out.printf("Perimeter: %.2f",perimeter);
}
}
```

Here,

*radius*and*perimeter*are two*double*values to hold the radius and perimeter of the circle.- It asks the user to enter the
*radius*and stores it in the*radius*variable. *perimeter*is calculated by using the above formula. For*π*, we are using*Math.PI*, which is the constant value defined in*Math*class.- The calculated
*perimeter*is printed in the last line.

If you run the above program, it will print output as like below:

```
Enter the radius of the circle:
10
Perimeter: 62.83
```

### Calculate the perimeter by using a different method:

We can also use a different method to calculate the *perimeter* of a circle. Below is the complete program:

```
import java.util.Scanner;
class Main {
public static double findPerimeter(double radius){
return 2 * Math.PI * radius;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
double radius, perimeter;
System.out.println("Enter the radius of the circle: ");
radius = scanner.nextDouble();
perimeter = findPerimeter(radius);
System.out.printf("Perimeter: %.2f",perimeter);
}
}
```

Here,

*findPerimeter*method is used to calculate the perimeter. It takes the*radius*value and returns the perimeter.

If we use a different method, we can call this method from any other place of other classes. If you run this program, it will print similar output.

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