General way to convert String into Big Decimal

Question

In my Java code I have four number in text format (String): Es.

String s1 = "1234.56";
String s2 = "1235,56";
String s3 = "1,234.56";
String s4 = "1.234,56";

I want to convert these Strings into BigDecimal:

BigDecimal b1 = new BigDecimal(s1);
...
...

Obviously it does not work, because BigDecimal does not accept all formats (strings with commas). There is a general way that allows me to convert all strings in BigDecimal?

score 1 · Answer 1 · edited Jun 20 '20 at 09:12

1

Decimal part is allways locale dependent, so you can use the NumberFormat class and use the parsed result as string to get a BigDecimal from it

Example:

final NumberFormat format = NumberFormat.getInstance(Locale.FRANCE);
final Number number = format.parse("3,1415");
final BigDecimal bd = new BigDecimal(number.toString());
System.out.println(bd);

edited Jun 20 '20 at 09:12

Community

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1

answered Oct 04 '16 at 14:37

ΦXocę 웃 Пepeúpa ツ

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Since `format.parse` [will return a Double](http://docs.oracle.com/javase/8/docs/api/java/text/NumberFormat.html#parse-java.lang.String-java.text.ParsePosition-), this will suffer from the same problem as the [BigDecimal(double) constructor](http://docs.oracle.com/javase/8/docs/api/java/math/BigDecimal.html#BigDecimal-double-): Inexact values that do not match the input string. – VGR Oct 04 '16 at 14:41
for string "s3" print 1.234 – fuerteVentura22 Oct 04 '16 at 15:01
yes, and 1.234 is a valid input to Bigdecimal – ΦXocę 웃 Пepeúpa ツ Oct 04 '16 at 15:02
1

But I want 1234.56 ! – fuerteVentura22 Oct 04 '16 at 15:38

BenB · Answer 2 · 2016-10-04T14:43:08.583

0

What about DecimalFormat ? Doc here

You just have to define a pattern for decimal separator before parsing the string...

 DecimalFormat decimalFormat = new DecimalFormat("#,###.##");
 decimalFormat.setParseBigDecimal(true);
 BigDecimal bigDecimal = (BigDecimal) decimalFormat.parse("1,234.56");
 System.out.println(bigDecimal);

Should do the trick

edited Oct 04 '16 at 14:43

answered Oct 04 '16 at 14:33

BenB

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Ok, but really I do not know the format of the "n" strings. use case is: I have an array of strings and I have to convert . – fuerteVentura22 Oct 04 '16 at 14:40
If you don't have pattern you can't parse anything. How to make difference between "1,234.56" and "1.234,56" without pattern ? – BenB Oct 04 '16 at 14:45
If you know that there is always 2 decimals you can pick the decimal separator to build the pattern I think.... – BenB Oct 04 '16 at 14:47
your code print 1.234 – fuerteVentura22 Oct 04 '16 at 15:05

Mike Shauneu · Answer 3 · 2016-10-04T15:19:29.400

To cover all cases I would suggest following impl:

private static BigDecimal convertToBigDecimal(String s) {
    StringBuilder sb = new StringBuilder();

    if (s.indexOf('.') != -1 && s.indexOf(',') != -1) {
        s = s.replace(',', '.');
        String[] ss = s.split("\\.");
        for (int i = 0; i < ss.length; i++) {
            if (i > 0 && i == ss.length - 1) {
                sb.append('.');
            }
            sb.append(ss[i]);
        }
    } else if (s.indexOf('.') != -1) {
        String[] ss = s.split("\\.");
        if (ss.length > 2) {
            sb.append(s.replace(".", ""));
        } else {
            // assume it is decimal delimiter
            sb.append(ss[0]).append('.').append(ss[1]);
        }
    } else if (s.indexOf(',') != -1) {
        String[] ss = s.split(",");
        if (ss.length > 2) {
            sb.append(s.replace(",", ""));
        } else {
            // assume it is decimal delimiter
            sb.append(ss[0]).append('.').append(ss[1]);
        }
    }

    BigDecimal bd = new BigDecimal(sb.toString());
    return bd;
}

The ideas is first check if we have both than we definitely have decimal part and we replace all , to . and then skip all . except last one. Otherwise if we have several same delimiters it is number without decimal part. In other case we need to know pattern to distinguish with decimal or not. For sample numbers we assume it is with decimal.

For "1,234,567" (no decimal part) the result will be wrong... (1234.567) But that's the best shot so far... — BenB, Oct 04 '16 at 14:53
You are right @BenB. It is unreal to distinguish without know a pattern for case 111,222 whether it is 1112222 or 111.222. — Mike Shauneu, Oct 04 '16 at 15:21

General way to convert String into Big Decimal

3 Answers3

Example: