相关疑难解决方法(0)

有人可以向我解释为什么以下代码:

public class Test {
    public static void main(String... args) {
        round(6.2088, 3);
        round(6.2089, 3);
    }

    private static void round(Double num, int numDecimal) {
        System.out.println("BigDecimal: " + new BigDecimal(num).toString());

        // Use Locale.ENGLISH for '.' as decimal separator
        NumberFormat nf = NumberFormat.getInstance(Locale.ENGLISH);
        nf.setGroupingUsed(false);
        nf.setMaximumFractionDigits(numDecimal);
        nf.setRoundingMode(RoundingMode.HALF_UP);

        if(Math.abs(num) - Math.abs(num.intValue()) != 0){
            nf.setMinimumFractionDigits(numDecimal);
        }

        System.out.println("Formatted: " + nf.format(num));
    }
}

给出以下输出？

[me@localhost trunk]$ java Test
BigDecimal: 6.208800000000000096633812063373625278472900390625
Formatted: 6.209
BigDecimal: 6.208899999999999863575794734060764312744140625
Formatted: 6.208

如果你没有看到它:"6.2089"四舍五入到3位给出输出"6.208"而"6.2088"给出"6.209"作为输出.少即是多？

使用Java 5,6或7时结果很好但是这个Java 8给了我这个奇怪的输出.Java版本:

[me@localhost trunk]$ java -version
java version …