在java中强制点（“.”）作为小数点分隔符

Question

I currently use the following code to print a double:

return String.format("%.2f", someDouble);

This works well, except that Java uses my Locale's decimal separator (a comma) while I would like to use a point. Is there an easy way to do this?

Answer 1

Use the overload of String.format which lets you specify the locale:

return String.format(Locale.ROOT, "%.2f", someDouble);

If you're only formatting a number - as you are here - then using NumberFormat would probably be more appropriate. But if you need the rest of the formatting capabilities of String.format , this should work fine.

Answer 2

A more drastic solution is to set your Locale early in the main().

Like:

Locale.setDefault(new Locale("en", "US"));

Answer 3

Way too late but as other mentioned here is sample usage of NumberFormat (and its subclass DecimalFormat )

public static String format(double num) {
    DecimalFormatSymbols decimalSymbols = DecimalFormatSymbols.getInstance();
    decimalSymbols.setDecimalSeparator('.');
    return new DecimalFormat("0.00", decimalSymbols).format(num);
 }

Answer 4

You can pass an additional Locale to java.lang.String.format as well as to java.io.PrintStream.printf (eg System.out.printf()):

import java.util.Locale;

public class PrintfLocales {

    public static void main(String args[]) {
        System.out.printf("%.2f: Default locale\n", 3.1415926535);
        System.out.printf(Locale.GERMANY, "%.2f: Germany locale\n", 3.1415926535);
        System.out.printf(Locale.US, "%.2f: US locale\n", 3.1415926535);
    }

}

This results in the following (on my PC):

$ java PrintfLocales
3.14: Default locale
3,14: Germany locale
3.14: US locale

See String.format in the Java API.

Answer 5

You can use NumberFormat and DecimalFormat.

Take a look at this link from Java Tutorials LocaleSpecific Formatting

The section titled Locale-Sensitive Formatting is what you need.

Answer 6

Change the language, it worked for me.

How to set eclipse console locale/language How to set eclipse console locale/language

Answer 7

I had the same issue.. 55.1 transformed to 55,10 . My quick (dirty?) fix is :

String.format("%.2f", value).replaceAll(",",".");