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How to use the Java Math.round() method
The Math.round() method in Java is used to round a number to its​ closest integer. This is done by adding to the number, taking the floor of the result, and casting the result to an integer data type.
Some of the edge cases of the Math.round() method are:
- If the argument is NaN (not a number), then the function will return .
- If the argument is negative infinity or any value less than or equal to the value of
Integer.MIN_VALUE, then the function returnsInteger.MIN_VALUE. - If the argument is positive infinity or any value greater than or equal to the value of
Integer.MAX_VALUE, then the function returnsInteger.MAX_VALUE.
Let’s see the implementation of the Math.round( ) method:
Basic use
We take a number 74.67 and pass it to the round() function. The output will be a nearest integer 75.
import java.lang.Math; // Needed to use Math.round()class Program {public static void main( String args[] ) {double num1 = 74.65;System.out.println(Math.round(num1));}}
Negative numbers
We pass a negative number -4.3 to the method and it returns -4.
import java.lang.Math; // Needed to use Math.round()class Program {public static void main( String args[] ) {double num1 = -4.3;System.out.println(Math.round(num1));}}
Specific decimal places
If we want to round a decimal number upto specific decimal places, in this case 2 decimal places we multiply it by 100.0 , pass it to the Math.round() method and then multiply it by 100.0 again.
import java.lang.Math; // Needed to use Math.round()class Program {public static void main( String args[] ) {double num1 = -13.56934;System.out.println(Math.round(num1 * 100.0) / 100.0); // Round to two decimal places}}
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