BigDecimal round() Method in Java

The java.math.BigDecimal.round(MathContext m) is an inbuilt method in Java that returns a BigDecimal value rounded according to the MathContext settings. If the precision setting is 0 then no rounding takes place.

Syntax:

public BigDecimal round(MathContext m)

Parameters: The method accepts a single parameter m which refers to the context to use that is the value up to which the BigDecimal value is to be rounded off.

Return value: This method returns a BigDecimal rounded according to the MathContext settings.

Below programs illustrate the working of java.math.BigDecimal.round(MathContext m) method:
Program 1:

// Java program to demonstrate the
// round() method
import java.math.*;

public class Gfg {

    public static void main(String[] args)
    {
        // Assign value to BigDecimal object b1
        BigDecimal b1 = new BigDecimal("4.2585");

        MathContext m = new MathContext(4); // 4 precision

        // b1 is rounded using m
        BigDecimal b2 = b1.round(m);

        // Print b2 value
        System.out.println("The value of " + b1 +
        " after rounding is " + b2);
    }
}

Output:

The value of 4.2585 after rounding is 4.259

Program 2:

// Java program to demonstrate the
// round() method
import java.math.*;

public class gfg {

    public static void main(String[] args)
    {
        // Assigning value to BigDecimal object b1
        BigDecimal b1 = new BigDecimal("-4.2585");

        MathContext m = new MathContext(4); // 4 precision

        // b1 is rounded using m
        BigDecimal b2 = b1.round(m);

        // Print b2 value
        System.out.println("The value of " + b1 +
        " after rounding is " + b2);
    }
}

Output:

The value of -4.2585 after rounding is -4.259

Reference: https://docs.oracle.com/javase/7/docs/api/java/math/BigDecimal.html#round(java.math.MathContext)