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javabigdecimal

Rounding the scientific notation of BigDecimal

I would like to print a BigDecimal in scientific notation so that the there are, say, 5 digits after the decimal point. For example: -3.12345E-51, 9.12345E100

.setScale() does not work in this case, because I don't know in advance the exponent of number in scientific notation. Moreover, BigDecimal doesn't seem to have a getExponent() method.

What's the best way to achieve this? Thank you in advance.

Solution

  • You should use DecimalFormat to print numbers in specified format:

        BigDecimal bigDecimal = new BigDecimal(-3.12345E-51);
    DecimalFormat format = new DecimalFormat("0.#####E0");
    System.out.println(format.format(bigDecimal));

    Also you can configure count of fraction digits using method DecimalFormat#setMaximumFractionDigits(int):

        DecimalFormat format = new DecimalFormat("0E0");
    format.setMaximumFractionDigits(6);