Java大十进制数格式异常

Question

为什么下面的代码抛出了java数字格式异常？

BigDecimal d = new BigDecimal("10934,375");

Answer 1

Yes, the BigDecimal class does not take any Locale into account in its constructor that takes a String , as can be read in the Javadoc of this constructor:

the fraction consists of a decimal point followed by zero or more decimal digits.

If you want to parse according to a different Locale , one that uses the comma as decimals separator, you need to use java.text.DecimalFormat with a specific Locale .

Example:

DecimalFormat fmt = new DecimalFormat("0.0", new DecimalFormatSymbols(Locale.GERMAN));
fmt.setParseBigDecimal(true);
BigDecimal n = (BigDecimal) fmt.parse("10934,375");

Note : you need to get an instance of DecimalFormat (a subclass of NumberFormat ) to be able to call the method setParseBigDecimal . Otherwise it returns a Double instead, which is a binary floating point number, and binary floating point numbers cannot accurately represent many decimal fractions . So that would cause a loss of accuracy in many cases.

Answer 2

The problem is that constructor of BigDecimal requires decimal number format where decimals come right after decimal dot . instead of decimal comma , so the right format for this specific case would be:

BigDecimal d = new BigDecimal("10934.375");

Answer 3

You can use NumberFormat to choose the Locale, see the example:

        String numberToFormat = "1.900,35";
        NumberFormat formatter = NumberFormat.getNumberInstance(Locale.GERMAN);
        Number number = formatter.parse(numberToFormat);
        BigDecimal decimal = BigDecimal.valueOf(number.doubleValue());