采纳您所说的内容，我对代码进行了一些修改，以涵盖不同的语言环境。关键是将本地化格式的值字符串转换为Double，然后根据格式字符串将其四舍五入。
格式字符串始终是基于英国的格式，十进制分隔符指定为“。” 和千位分隔符指定为“，”。
我正在使用DecimalFormat最初基于指定的语言环境解析本地化格式。这样可以正确给出字符串的Double等效值。然后，我使用BigDecimal处理舍入。我可以从DecimalFormat实例中获取小数位数，然后在BigDecimal上调用setScale进行舍入。
初始代码结构已被修改，以允许您查看在不同的语言环境下发生的情况，这感谢@ RD01注意其他语言环境的重要性。
我现在有如下代码：
private void runTests3() { // output current locale we are running under System.out.println( "Current Locale is " + Locale.getDefault().toString() ); // number in Central European Format with a format string specified in UK format String numbersInEuropeanFormatString[] = new String[] { "1.000,234567", "1,2345678", "1.222.333,234567" }; String formatUK = "###,##0.0000"; // output numbers using the german locale System.out.println("Output numbers using the German localen"); for(String num : numbersInEuropeanFormatString ) { formatNumberAsDouble(num, formatUK, Locale.GERMAN); } // output numbers using the UK locale. // this should return unexpected results as the number is in European format System.out.println("Output numbers using the UK localen"); for(String num : numbersInEuropeanFormatString ) { formatNumberAsDouble(num, formatUK, Locale.UK); } // output numbers using new DecimalFormat( formatUK ) - no locale specified System.out.println("nnOutput numbers using new DecimalFormat( " + formatUK + " )n"); for(String num : numbersInEuropeanFormatString ) { formatNumberAsDouble( num, formatUK, null); }}private void formatNumberAsDouble(String value, String format, Locale locale) { NumberFormat formatter; int decimalPlaces; // create the formatter based on the specified locale if( locale != null ) { formatter = NumberFormat.getNumberInstance(locale); // creating the above number format does not take in the format string // so create a new one that we won't use at all just to get the // decimal places in it decimalPlaces = (new DecimalFormat(format)).getMaximumFractionDigits(); } else { formatter = new DecimalFormat( format ); decimalPlaces = formatter.getMaximumFractionDigits(); } // get the result as number Double result = null; try { result = formatter.parse( value ).doublevalue(); } catch( ParseException ex ) { // not bothered at minute } // round the Double to the precision specified in the format string BigDecimal bd = new BigDecimal(result ); Double roundedValue = bd.setScale( decimalPlaces, RoundingMode.HALF_UP ).doublevalue(); // output summary System.out.println("tValue = " + value); System.out.println( locale == null ? "tLocale not specified" : "tLocale = " + locale.toString()); System.out.println( format == null || format.length() == 0 ? "tFormat = Not specified" : "tFormat = " + format); System.out.println("tResult (Double) = " + result); System.out.println("tRounded Result (Double) (" + decimalPlaces + "dp) = " + roundedValue); System.out.println("");}这将产生以下输出：
Current Locale is nl_BEOutput numbers using the German locale Value = 1.000,234567 Locale = de Format = ###,##0.0000 Result (Double) = 1000.234567 Rounded Result (Double) (4dp) = 1000.2346 Value = 1,2345678 Locale = de Format = ###,##0.0000 Result (Double) = 1.2345678 Rounded Result (Double) (4dp) = 1.2346 Value = 1.222.333,234567 Locale = de Format = ###,##0.0000 Result (Double) = 1222333.234567 Rounded Result (Double) (4dp) = 1222333.2346Output numbers using the UK locale Value = 1.000,234567 Locale = en_GB Format = ###,##0.0000 Result (Double) = 1.0 Rounded Result (Double) (4dp) = 1.0 Value = 1,2345678 Locale = en_GB Format = ###,##0.0000 Result (Double) = 1.2345678E7 Rounded Result (Double) (4dp) = 1.2345678E7 Value = 1.222.333,234567 Locale = en_GB Format = ###,##0.0000 Result (Double) = 1.222 Rounded Result (Double) (4dp) = 1.222Output numbers using new DecimalFormat( ###,##0.0000 ) Value = 1.000,234567 Locale not specified Format = ###,##0.0000 Result (Double) = 1000.234567 Rounded Result (Double) (4dp) = 1000.2346 Value = 1,2345678 Locale not specified Format = ###,##0.0000 Result (Double) = 1.2345678 Rounded Result (Double) (4dp) = 1.2346 Value = 1.222.333,234567 Locale not specified Format = ###,##0.0000 Result (Double) = 1222333.234567 Rounded Result (Double) (4dp) = 1222333.2346
