## Java program to find the volume of a cylinder:

In this post, we will learn how to find the *volume* of a *cylinder* in Java. We will learn different ways to do the calculation. We need the *height* and *radius* of a cylinder to calculate its volume. The program will take these values as inputs from the user, calculate the volume of that cylinder and print the value.

### How to find the volume of a cylinder:

To find the volume of a cylinder, we need its *height* and *radius*. Once we get these values, we can find the *volume* of that cylinder with the below formula:

`π * r * r * h`

Where π is the mathematical constant PI, *r* is the radius of the cylinder and *h* is the height of the cylinder.

The program will take the *radius* and *height* of the cylinder as inputs from the user and calculate the volume of the cylinder with the above formula.

### Method 1: Basic program to find the volume of a cylinder:

Let’s take a look at the below program:

```
class Main {
public static void main(String[] args) {
double radius = 40, height = 28;
double PI = 3.1415926;
double volume = PI * radius * radius * height;
System.out.println("Volume of the cylinder is: " + volume);
}
}
```

Here, the value of the *radius, height*, **and *PI* are predefined. All of these are predefined values and the volume is calculated by using the above formula.

It will print the below output:

`Volume of the cylinder is: 140743.34848000002`

### Method 2: Example to find the volume of a cylinder by taking the values as inputs from the user:

The above program uses predefined values. We can also take these values as inputs from the user. The value of *PI* is already defined in the *Math* class. We can use it instead of creating another double value. Let’s write down the program:

```
import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
double radius, height;
double PI = Math.PI;
System.out.println("Enter the radius of the cylinder: ");
radius = sc.nextDouble();
System.out.println("Enter the height of the cylinder: ");
height = sc.nextDouble();
double volume = PI * radius * radius * height;
System.out.println("Volume of the cylinder is: " + volume);
}
}
```

In the above program, we are reading the *radius* and *height* values as inputs from the user. A *scanner* object is used to read the user-input values. The *PI* value is used from *Math.PI*. The volume is calculated as per the above formula.

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

```
Enter the radius of the cylinder:
30
Enter the height of the cylinder:
40
Volume of the cylinder is: 113097.33552923254
```

### Method 3: Example to find the volume of a cylinder by using a separate method:

We can use a separate method to calculate the *volume of the cylinder*. The advantage of using a separate method is that we can call this method from different classes. It will take the *radius* and *height* as parameters and return the volume of the cylinder.

Below is the program:

```
import java.util.Scanner;
import static java.lang.Math.PI;
class Main {
public static double getCylinderVolume(double radius, double height) {
return PI * radius * radius * height;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
double radius, height;
System.out.println("Enter the radius of the cylinder: ");
radius = sc.nextDouble();
System.out.println("Enter the height of the cylinder: ");
height = sc.nextDouble();
double volume = getCylinderVolume(radius, height);
System.out.println("Volume of the cylinder is: " + volume);
}
}
```

Here,

*getCylinderVolume*method is used to get the volume of the cylinder. It takes the*radius*and*height*as the parameters and returns the volume. The returned value is stored in the variable*volume*. The last line is printing the volume value.

It will give similar results:

```
Enter the radius of the cylinder:
30
Enter the height of the cylinder:
40
Volume of the cylinder is: 113097.33552923254
```

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