Java - Math round(double x) method

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Description

The Java Math round(double a) returns the closest long to the argument. The result is rounded to an integer by adding 1/2, taking the floor of the result, and casting the result to type long. Special cases −

• If the argument is NaN, the result is 0.

• If the argument is negative infinity or any value less than or equal to the value of Long.MIN_VALUE, the result is equal to the value of Long.MIN_VALUE.

• If the argument is positive infinity or any value greater than or equal to the value of Long.MAX_VALUE, the result is equal to the value of Long.MAX_VALUE.

Declaration

Following is the declaration for java.lang.Math.round() method

public static long round(double a)

Parameters

a − a floating-point value to be rounded to a long.

Return Value

This method returns the value of the argument rounded to the nearest long value.

Exception

NA

Example: Getting a Rounded long for a Positive double Value

The following example shows the usage of Math round() method to get a long value for a positive double value.

package com.tutorialspoint;
public class MathDemo {
   public static void main(String[] args) {

      // get a double number
      double x = 1654.9874;

      // find the closest long for this double number
      System.out.println("Math.round(" + x + ")=" + Math.round(x));
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Math.round(1654.9874)=1655

Example: Getting a Rounded long for a Negative double Value

The following example shows the usage of Math round() method to get a long value for a negative double value.

package com.tutorialspoint;
public class MathDemo {
   public static void main(String[] args) {

      // get a double number
      double x = -9765.134;

      // find the closest long for this double number
      System.out.println("Math.round(" + x + ")=" + Math.round(x));
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Math.round(-9765.134)=-9765

Example: Getting a Rounded long for a Zero double Value

The following example shows the usage of Math round() method to get a long value for a zero double values.

package com.tutorialspoint;
public class MathDemo {
   public static void main(String[] args) {

      // get double numbers
      double x = -0.0;
      double y = 0.0;	  

      // find the long for these double number
      System.out.println("Math.round(" + x + ")=" + Math.round(x));
	  System.out.println("Math.round(" + y + ")=" + Math.round(y));
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Math.round(-0.0)=0
Math.round(0.0)=0