Java: How to round a float or double to an integer

Java math FAQ: How do I round a float or double number to an integer in Java?

Solution: Use Math.round() to round a float (or double) to the nearest integer (int) in Java.

You can see how this works in the examples that follow, where the result is shown in the comment after each line:

package float2int;

public class TestClass {

public static void main(String[] args) {

System.out.println(Math.round(1.9)); // 2
System.out.println(Math.round(2.0)); // 2
System.out.println(Math.round(2.1)); // 2

System.out.println(Math.round(2.4)); // 2
System.out.println(Math.round(2.5)); // 3
System.out.println(Math.round(2.6)); // 3

}

}

Cast to an int

Note that as a practical matter you may need to cast the Math.round result to an int, like this:

int x = (int) Math.round(2.6);

This is because Math.round is overloaded, and one version of the method returns an int, and the other version returns a long. If the round method thinks it is receiving a float, it will return an int, so this works:

int x = Math.round(2.6f);

But if round thinks it’s receiving a double it will return a long, so casting it to an int like this is necessary:

int y = (int) Math.round(2.6);

The first of these two examples works because I have explicitly given round a float when I wrote 2.6f.

In summary, if you want to round a float or double to an int in Java, I hope this is helpful.