Java

# How to Use Pi in Java

Programmers use various mathematical formulas in order to address real-world challenges. Pi is one of the most essential and interesting integers in mathematics. It can calculate to an unlimited number of decimal places without falling into a repeating pattern because it is an irrational number.

## How to Use Pi in Java?

The general value of Pi is “3.14”. It is primarily utilized for calculating the Area and Circumference of a circle. It is also utilized in several mathematical formulas, functions, and constants.

In Java, Pi can be used as:

We will now check out both of the mentioned methods one by one.

## Method 1: Use Pi in Java as Pre-defined Constant

Java programmers can utilize the “Math.PI” constant of the “java.lang” package. It is a static double type constant that belongs to the Java Math class:

public static final double PI = 3.14159265358979323846;

Note: The “final” keyword is utilized for defining a constant that maintains its value and keeps it the same during the execution.

As the Pi (π) is the static variable, you can call its value by using the class name or by adding the Math library in the code and accessing the PI constant.

Syntax

The syntax for calling PI by using the Math class name is given as:

Math.PI

Or import Math class and call the PI constant where needed:

import static java.lang.Math.*;

Have a look at the given examples to learn about the usage of Pi as a Pre-defined constant.

### Example: Using Math.PI in Java

In this example, we will use Math.PI as a Pre-defined constant to find the area of a circle. The formula for the area of a circle is given as “πr^2”. We will specify the radius value as “11” and store it in an integer type variable named “rad”. The calculated area by using Math.PI will be stored in a double type “area” variable:

System.out.println("The area of circle is: "+ area); The given output indicates that we have successfully accessed the value of Math.PI and evaluated the area of the circle: Let’s check out the other method of using the Pi Constant.

## Method 2: Using Pi in Java as User-defined Constant

Pi can also be utilized in Java as a User-defined constant. In this method, you have to assign a value to the Pi variable by yourself and then use it where needed.

### Example

Here, we will find the circle’s circumference without calling the predefined “PI” constant. To do so, firstly, we will create two variables, “rad” of int type for storing radius and “pi” double type for the saving the value of pi as “3.14”:

double pi = 3.14;

Next, we will create another double type variable for storing results named “circumference”. The circle circumference’s formula is given as “2*(pi*r)” print it by using the “System.out.println()” method:

double circumference = 2*(pi*r);

System.out.println("The circumference of circle is: "+ circumference); As you can see, our Java program calculated the circle circumference based on the User-defined Pi value: We have provided all the essential instructions related to the usage of Pi in Java.

## Conclusion

In Java, Pi can be used as a Pre-defined constant “Math.PI” and a User-defined constant. For using Pre-defined constants, you can either call the Math.PI constant of the Math class or import the Math class in your projects. However, in the User-defined Pi constant, you can set the value of Pi to a variable and then utilize it. This blog illustrated the use of Pi in Java with detailed examples. 