Java

# How to round of Numbers in Java

Java provides a built-in class known as Math class which belongs to the java.lang package. The java.lang.Math class provides numerous methods that are used to perform different numeric operations such as rounding of a number, finding square root, and so on. The Math class offers multiple methods to round off a number such as round(), ceil(), floor().

This article will provide a profound knowledge about how to round of numbers in java. In this write-up we will cover the below listed method to round of a number in java:

• What is Math.round() and how to use it in Java
• What is Math.ceil() and how to use it in Java
• What is Math.floor() and how to use it in Java

So, let’s get started!

## What is Math.round() and how to use it in Java

It is a predefined method of Java’s Math class that cuts off the floating value and returns the closest integer-type number.

Example
This example will assist you to understand how to use the Math.round() method in java:

public class RoundingOfNumber {
public static void main(String[] args) {
float number1 = 172.52f;
double number2 = 172.12;
float number3 = 10.12f;
float number4 = 10.72f;
double number5 = -570.82;

System.out.println("Rounding of 172.52: " + Math.round(number1));
System.out.println("Rounding of 172.12: " + Math.round(number2));
System.out.println("Rounding of 10.12: " + Math.round(number3));
System.out.println("Rounding of 10.72: " + Math.round(number4));
System.out.println("Rounding of -570.82: " + Math.round(number5));
}
}

Above program will produce the following output:

The output shows that the Math.round() method returned the closest integer number.

## What is Math.ceil() and how to use it in Java

It is a predefined method of Java’s Math class that rounds the given number upward and returns the double-type value; the below-given example will provide you more clarity on this concept.

Example
We will modify the previous example and instead of Math.round() method we will utilize the Math.ceil() method:

public class RoundingOfNumber {
public static void main(String[] args) {
float number1 = 172.52f;
double number2 = 172.12;
float number3 = 10.12f;
float number4 = 10.72f;
double number5 = -570.82;

System.out.println("Rounding of 172.52: " + Math.ceil(number1));
System.out.println("Rounding of 172.12: " + Math.ceil(number2));
System.out.println("Rounding of 10.12: " + Math.ceil(number3));
System.out.println("Rounding of 10.72: " + Math.ceil(number4));
System.out.println("Rounding of -570.82: " + Math.ceil(number5));
}
}

On successful execution of the program, we will get the following output:

The output shows that the Math.ceil() method returned upward nearest double-type values.

## What is Math.floor() and how to use it in Java

This method opposes the concept of Math.ceil() method i.e. it rounds the given number downward and returns the double-type value.

Example
Let’s consider the below-given program to understand the working of the Math.floor() method.

public class RoundingOfNumber {
public static void main(String[] args) {
float number1 = 172.52f;
double number2 = 172.12;
float number3 = 10.12f;
float number4 = 10.72f;
double number5 = -570.82;

System.out.println("Rounding of 172.52: " + Math.floor(number1));
System.out.println("Rounding of 172.12: " + Math.floor(number2));
System.out.println("Rounding of 10.12: " + Math.floor(number3));
System.out.println("Rounding of 10.72: " + Math.floor(number4));
System.out.println("Rounding of -570.82: " + Math.floor(number5));
}
}

On successful execution of the above given code, we will get the following output:

The output shows that the Math.floor() method returned the downward nearest double-type values.

## Conclusion

The Math class provides three methods to round off a number i.e. round(), ceil(), floor(). The math.round() method cuts off the floating value and returns the closest integer-type number. The ceil() method rounds the given number upward and returns the double-type value while the floor() method rounds the given number downward and returns the double-type value. This write-up explained the working of three built-in methods to round off a number in java i.e. round(), ceil(), and floor().