.rint()

The Math.rint() returns a double that is rounded to the closest whole integer.

Syntax

Math.rint(num)

The .rint() method takes a double num parameter and returns a double.

Some edge cases for the .rint() method include the following:

• If the value of num is passed an integer, then it is returned as a double.
• If the value of num is NaN or positive/negative infinity, then the value of num is returned.
• If the value of num is positive/negative zero, then 0.0 is returned.

Example

The following example demonstrates the .rint() method:

public class Test {
  public static void main(String[] args) {

    System.out.println(Math.rint(8.75));
    // When the whole number is odd and the fractional part is .5, round up.
    System.out.println(Math.rint(3.5));
    // When the whole number is even and the fractional part is .5, round down.
    System.out.println(Math.rint(6.5));

    // Edge cases
    System.out.println(Math.rint(-0));
    System.out.println(Math.rint(Double.NaN));
    System.out.println(Math.rint(Double.POSITIVE_INFINITY));
    System.out.println(Math.rint(Double.NEGATIVE_INFINITY));
  }
}

This will produce the following output:

9.0
4.0
6.0
0.0
NaN
Infinity
-Infinity