How to round any number to n decimal places in Java

Question

I am dealing with different numerical values. But, I want specific digit decimal values. What will be the solution for this?

Answer 1

You can use setRoundingMode() method to get n digit decimal values.

To write a solution for this question, you have to import 3 libraries.

import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.util.Arrays;

After importing these libraries, write the statements given below.

public static void main(String[] args) {

DecimalFormat df = new DecimalFormat("#.##");

df.setRoundingMode(RoundingMode.CEILING);

for (Number n : Arrays.asList(15.00000, 13.23456)) {

    Double d = n.doubleValue();

    System.out.println(df.format(d));

}
}

Output will be: 

15
13.24

Answer 2

new BigDecimal(String.valueOf(double)).setScale(yourScale, BigDecimal.ROUND_HALF_UP);

will get you a BigDecimal. To get the string out of it, just call that BigDecimal's toStringmethod, or the toPlainString method for Java 5+ for a plain format string.

Sample program:

package trials;
import java.math.BigDecimal;

public class Trials {

    public static void main(String[] args) {
        int yourScale = 10;
        System.out.println(BigDecimal.valueOf(0.42344534534553453453-0.42324534524553453453).setScale(yourScale, BigDecimal.ROUND_HALF_UP));
    }