Rounded up value is received when using setMaximumFractionDigits

Question

I'm new to Java and stuck at an issue. below is the sample program i made for the same.

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.Currency;
import java.util.Locale;
import java.math.RoundingMode;
import java.math.BigDecimal;

public class Main {
    public static void main(String[] args)
    {
        Object fieldVal = null;
        // Create the DecimalFormat Instance
        DecimalFormat deciFormat = new DecimalFormat();
        String valStr = "31363.214722222422";

        deciFormat.setMaximumFractionDigits(15);
        
        try {
            fieldVal = new BigDecimal(deciFormat.parse(valStr).toString());
        }
        catch (java.text.ParseException e){
            
        }
        System.out.println(fieldVal);
    }
}

Here I'm expecting the output as 31363.214722222422 but instead I'm getting 31363.214722222423. I observed that this rounding up happens for 12th decimal place. If I use till 11 decimal place, it works absolutely fine. I even tried to avoid rounding up with deciFormat.setRoundingMode(RoundingMode.DOWN);, but it didn't work.

Need some guidance to solve this issue.

Answer 1

Don't use DecimalFormat because it will use double internally. Instead parse it directly using new BigDecimal(String)