## How to use pi value in Java:

Mathematical constant *PI* or *π* is already defined in the *Math* class or *java.lang.Math* class in Java. *π* is the ratio of the *circumference* of a circle to its diameter and it is a constant value.

It is a *public static final* double value and it is defined as like below:

`public static final double PI = 3.14159265358979323846;`

In this post, we will learn how to use this value in different ways.

### Use PI without importing Math module:

Since *Math* class is defined in the *java.lang* package, we can use its methods and other constants without importing this class. Also, since *PI* is a

The below program is printing the value of *PI* without using any imports:

```
public class Main{
public static void main(String[] args){
System.out.println(Math.PI);
}
}
```

If you run this program, it will print the value of *PI*.

### Use PI with static import:

Another way is to use *static import*. We can use *static import* to import the *Math* module and its constant can be accessed with using *Math*. For example:

```
import static java.lang.Math.*;
public class Main{
public static void main(String[] args){
System.out.println(PI);
}
}
```

Here,

- We are using static import,
*import static java.lang.Math.**and it imports all methods and constants defined in the*Math*class. - We are accessing the value of
*PI*without using*Math*.

### Use static import to import only PI:

The above example imports all methods and constants defined in the *Math* class. But, we can also import *PI*. We are not using any other methods or constants from the *Math* class. So, insted we can import only *PI* as like below:

```
import static java.lang.Math.PI;
public class Main{
public static void main(String[] args){
System.out.println(PI);
}
}
```

Instead of ***, we are using *PI* to import it directly from the *Math* class. It also uses static import.

### Example of PI:

Let’s take an example of *PI*. *PI* is used to find the area of a circle. So, if we are writing a program in *Java* to calculate the area of a circle, we can use the *Math* module to read the *PI* value.

The formula to calculate the area of a circle is:

`Pi * R * R`

Where *R* is the radius.

Let’s write a program that take the radius as input and prints the *area*.

```
import java.util.Scanner;
import static java.lang.Math.PI;
public class Main {
public static void main(String[] args) {
double r, area;
Scanner sc = new Scanner(System.in);
System.out.println("Enter the radius of the circle: ");
r = sc.nextFloat();
area = PI * r * r;
System.out.println("Area of the circle is: " + area);
}
}
```

It will give output as like below:

```
Enter the radius of the circle:
12
Area of the circle is: 452.3893421169302
Enter the radius of the circle:
10
Area of the circle is: 314.1592653589793
```

It is taking the *radius* as input from the user and printing the *area*. We are using static import to import *PI* and using its value, we are calculating the value of *area*.

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