Safe String to BigDecimal conversion

Question

I'm trying to read some BigDecimal values from the string. Let's say I have this String: "1,000,000,000.999999999999999" and I want to get a BigDecimal out of it. What is the way to do it?

First of all, I don't like the solutions using string replaces (replacing commas etc.). I think there should be some neat formatter to do that job for me.

I've found a DecimalFormatter class, however as it operates through double - huge amounts of precision are lost.

So, how can I do it?

Thanks in advance.

Answer 1

Check out this method in DecimalFormat. With this setter, the parse method will return a BigDecimal for you.

Answer 2

Here is how I would do it:

public String cleanDecimalString(String input, boolean americanFormat) {
    if (americanFormat)
        return input.replaceAll(",", "");
    else
        return input.replaceAll(".", "");
}

Obviously, if this were going in production code, it wouldn't be that simple.

I see no issue with simply removing the commas from the String.

Answer 3

String value = "1,000,000,000.999999999999999";
BigDecimal money = new BigDecimal(value.replaceAll(",", ""));
System.out.println(money);

---

Full code to prove that no NumberFormatException is thrown:

/**
 * 
 */

import java.math.BigDecimal;

/**
 * @author The Elite Gentleman
 *
 */
public class Tester {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String value = "1,000,000,000.999999999999999";
        BigDecimal money = new BigDecimal(value.replaceAll(",", ""));
        System.out.println(money);
    }

}

Output

1000000000.999999999999999

Answer 4

resultString = subjectString.replaceAll("[^.\\d]", "");

will remove all characters except digits and the dot from your string.

To make it locale-aware, you might want to use getDecimalSeparator() from java.text.DecimalFormatSymbols. I don't know Java, but it might look like this:

sep = getDecimalSeparator()
resultString = subjectString.replaceAll("[^"+sep+"\\d]", "");

Answer 5

The code could be cleaner, but this seems to do the trick for different locales.

import java.math.BigDecimal;
import java.text.DecimalFormatSymbols;
import java.util.Locale;


public class Main
{
    public static void main(String[] args)
    {
        final BigDecimal numberA;
        final BigDecimal numberB;

        numberA = stringToBigDecimal("1,000,000,000.999999999999999", Locale.CANADA);
        numberB = stringToBigDecimal("1.000.000.000,999999999999999", Locale.GERMANY);
        System.out.println(numberA);
        System.out.println(numberB);
    }

    private static BigDecimal stringToBigDecimal(final String formattedString,
                                                 final Locale locale)
    {
        final DecimalFormatSymbols symbols;
        final char                 groupSeparatorChar;
        final String               groupSeparator;
        final char                 decimalSeparatorChar;
        final String               decimalSeparator;
        String                     fixedString;
        final BigDecimal           number;

        symbols              = new DecimalFormatSymbols(locale);
        groupSeparatorChar   = symbols.getGroupingSeparator();
        decimalSeparatorChar = symbols.getDecimalSeparator();

        if(groupSeparatorChar == '.')
        {
            groupSeparator = "\\" + groupSeparatorChar;
        }
        else
        {
            groupSeparator = Character.toString(groupSeparatorChar);
        }

        if(decimalSeparatorChar == '.')
        {
            decimalSeparator = "\\" + decimalSeparatorChar;
        }
        else
        {
            decimalSeparator = Character.toString(decimalSeparatorChar);
        }

        fixedString = formattedString.replaceAll(groupSeparator , "");
        fixedString = fixedString.replaceAll(decimalSeparator , ".");
        number      = new BigDecimal(fixedString);

        return (number);
    }
}