Class DoubleFormatUtil


  • public final class DoubleFormatUtil
    extends java.lang.Object
    This class implements fast, thread-safe format of a double value with a given number of decimal digits.

    The contract for the format methods is this one: if the source is greater than or equal to 1 (in absolute value), use the decimals parameter to define the number of decimal digits; else, use the precision parameter to define the number of decimal digits.

    A few examples (consider decimals being 4 and precision being 8):

    • 0.0 should be rendered as "0"
    • 0.1 should be rendered as "0.1"
    • 1234.1 should be rendered as "1234.1"
    • 1234.1234567 should be rendered as "1234.1235" (note the trailing 5! Rounding!)
    • 1234.00001 should be rendered as "1234"
    • 0.00001 should be rendered as "0.00001" (here you see the effect of the "precision" parameter)
    • 0.00000001 should be rendered as "0.00000001"
    • 0.000000001 should be rendered as "0"
    Originally authored by Julien Aymé.
    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static void formatDouble​(double source, int decimals, int precision, java.lang.StringBuffer target)
      Rounds the given source value at the given precision and writes the rounded value into the given target
      static void formatDoubleFast​(double source, int decimals, int precision, java.lang.StringBuffer target)
      Rounds the given source value at the given precision and writes the rounded value into the given target
      static void formatDoublePrecise​(double source, int decimals, int precision, java.lang.StringBuffer target)
      Rounds the given source value at the given precision and writes the rounded value into the given target
      static int getExponant​(double value)
      Returns the exponent of the given value
      static long tenPow​(int n)
      Returns ten to the power of n
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Method Detail

      • formatDouble

        public static void formatDouble​(double source,
                                        int decimals,
                                        int precision,
                                        java.lang.StringBuffer target)
        Rounds the given source value at the given precision and writes the rounded value into the given target
        Parameters:
        source - the source value to round
        decimals - the decimals to round at (use if abs(source) ≥ 1.0)
        precision - the precision to round at (use if abs(source) < 1.0)
        target - the buffer to write to
      • formatDoublePrecise

        public static void formatDoublePrecise​(double source,
                                               int decimals,
                                               int precision,
                                               java.lang.StringBuffer target)
        Rounds the given source value at the given precision and writes the rounded value into the given target

        This method internally uses the String representation of the source value, in order to avoid any double precision computation error.

        Parameters:
        source - the source value to round
        decimals - the decimals to round at (use if abs(source) ≥ 1.0)
        precision - the precision to round at (use if abs(source) < 1.0)
        target - the buffer to write to
      • tenPow

        public static long tenPow​(int n)
        Returns ten to the power of n
        Parameters:
        n - the nth power of ten to get
        Returns:
        ten to the power of n
      • formatDoubleFast

        public static void formatDoubleFast​(double source,
                                            int decimals,
                                            int precision,
                                            java.lang.StringBuffer target)
        Rounds the given source value at the given precision and writes the rounded value into the given target

        This method internally uses double precision computation and rounding, so the result may not be accurate (see formatDouble method for conditions).

        Parameters:
        source - the source value to round
        decimals - the decimals to round at (use if abs(source) ≥ 1.0)
        precision - the precision to round at (use if abs(source) < 1.0)
        target - the buffer to write to
      • getExponant

        public static int getExponant​(double value)
        Returns the exponent of the given value
        Parameters:
        value - the value to get the exponent from
        Returns:
        the value's exponent