Converting different countrys currency to double using java

Question

I have once scenario where in i get the currencies as a String, for eg:

$199.00

R$ 399,00

£25.00

90,83 €

AED 449.00

How do i convert these currencies to double in java?

Answer 1

Never use double for representing exact amounts

Well, of course you can do, but you need to really understand floating point arithmetic

Use a NumberFormat. Whilst it does handle some currencies, it's usually easier just to strip all the currency symbols. The NumberFormat will use Locale to work out the delimiters to use:

public static BigDecimal parse(final String amount, final Locale locale) throws ParseException {
    final NumberFormat format = NumberFormat.getNumberInstance(locale);
    if (format instanceof DecimalFormat) {
        ((DecimalFormat) format).setParseBigDecimal(true);
    }
    return (BigDecimal) format.parse(amount.replaceAll("[^\\d.,]",""));
}

This takes a String of the amount and the Locale. It then creates a BigDecimal parsing NumberFormat instance. It uses replaceAll and regex to strip all but digits, . and , from the number then parses it.

A quick demo against your examples:

public static void main(String[] args) throws ParseException {
    final String dollarsA = "$199.00";
    final String real = "R$ 399,00";
    final String dollarsB = "£25.00";
    final String tailingEuro = "90,83 €";
    final String dollarsC = "$199.00";
    final String dirham = "AED 449.00";

    System.out.println(parse(dollarsA, Locale.US));
    System.out.println(parse(real, Locale.FRANCE));
    System.out.println(parse(dollarsB, Locale.US));
    System.out.println(parse(tailingEuro, Locale.FRANCE));
    System.out.println(parse(dollarsC, Locale.US));
    System.out.println(parse(dirham, Locale.US));
}

Output:

199.00
399.00
25.00
90.83
199.00
449.00

I have simply used US where the decimal is . and FRANCE where the decimal is , but you could use the correct Locale for the currency if you wish.