# How to Calculate the Area of a Circle in Java

Java is used extensively in mathematics because of how easy it is to perform calculations across different platforms.

One of the most common calculations is to calculate the area of a circle.

In this post, we'll learn how to calculate the area of a circle in Java.

## How to calculate the area of a circle

The formula to calculate the area of a circle is well-known, it is `πr²`

.

Meaning we just take the radius of the circle and multiply it by itself, and then multiply it by `pi`

.

Thankfully, we can use `pi`

in Java by using the `Math.PI`

constant.

Let's first start off with the example code:

` ````
double radius = 5;
double area = Math.PI * radius * radius;
System.out.println(area);
```

` ``78.53981633974483`

Now, we can turn this into a re-usable method that accepts a radius as the parameter:

` ````
public static double calculateArea(double radius) {
return Math.PI * radius * radius;
}
```

Now we can just call this method:

` ````
double area = calculateArea(5);
System.out.println(area);
```

` ``78.53981633974483`

Either way, it is very easy to calculate the area of a circle, and this reusable method can be used in any Java program.

## Conclusion

In this post, we learned how to calculate the area of a circle in Java.

Simply apply the formula `πr²`

with your desired radius and you'll get the area of the circle.

Thanks for reading and happy coding!

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