Class RoundingUtils


  • public class RoundingUtils
    extends java.lang.Object
    • Field Detail

      • DEFAULT_ROUNDING_MODE

        public static final java.math.RoundingMode DEFAULT_ROUNDING_MODE
        The default rounding mode.
      • MAX_INT_FRAC_SIG

        public static final int MAX_INT_FRAC_SIG
        The maximum number of fraction places, integer numerals, or significant digits. TODO: This does not feel like the best home for this value.
        See Also:
        Constant Field Values
      • MATH_CONTEXT_BY_ROUNDING_MODE_UNLIMITED

        private static final java.math.MathContext[] MATH_CONTEXT_BY_ROUNDING_MODE_UNLIMITED
      • MATH_CONTEXT_BY_ROUNDING_MODE_34_DIGITS

        private static final java.math.MathContext[] MATH_CONTEXT_BY_ROUNDING_MODE_34_DIGITS
      • DEFAULT_MATH_CONTEXT_UNLIMITED

        public static final java.math.MathContext DEFAULT_MATH_CONTEXT_UNLIMITED
        The default MathContext, unlimited-precision version.
      • DEFAULT_MATH_CONTEXT_34_DIGITS

        public static final java.math.MathContext DEFAULT_MATH_CONTEXT_34_DIGITS
        The default MathContext, 34-digit version.
    • Constructor Detail

      • RoundingUtils

        public RoundingUtils()
    • Method Detail

      • getRoundingDirection

        public static boolean getRoundingDirection​(boolean isEven,
                                                   boolean isNegative,
                                                   int section,
                                                   int roundingMode,
                                                   java.lang.Object reference)
        Converts a rounding mode and metadata about the quantity being rounded to a boolean determining whether the value should be rounded toward infinity or toward zero.

        The parameters are of type int because benchmarks on an x86-64 processor against OpenJDK showed that ints were demonstrably faster than enums in switch statements.

        Parameters:
        isEven - Whether the digit immediately before the rounding magnitude is even.
        isNegative - Whether the quantity is negative.
        section - Whether the part of the quantity to the right of the rounding magnitude is exactly halfway between two digits, whether it is in the lower part (closer to zero), or whether it is in the upper part (closer to infinity). See SECTION_LOWER, SECTION_MIDPOINT, and SECTION_UPPER.
        roundingMode - The integer version of the RoundingMode, which you can get via Enum.ordinal.
        reference - A reference object to be used when throwing an ArithmeticException.
        Returns:
        true if the number should be rounded toward zero; false if it should be rounded toward infinity.
      • roundsAtMidpoint

        public static boolean roundsAtMidpoint​(int roundingMode)
        Gets whether the given rounding mode's rounding boundary is at the midpoint. The rounding boundary is the point at which a number switches from being rounded down to being rounded up. For example, with rounding mode HALF_EVEN, HALF_UP, or HALF_DOWN, the rounding boundary is at the midpoint, and this function would return true. However, for UP, DOWN, CEILING, and FLOOR, the rounding boundary is at the "edge", and this function would return false.
        Parameters:
        roundingMode - The integer version of the RoundingMode.
        Returns:
        true if rounding mode is HALF_EVEN, HALF_UP, or HALF_DOWN; false otherwise.
      • getMathContextOrUnlimited

        public static java.math.MathContext getMathContextOrUnlimited​(DecimalFormatProperties properties)
        Gets the user-specified math context out of the property bag. If there is none, falls back to a math context with unlimited precision and the user-specified rounding mode, which defaults to HALF_EVEN (the IEEE 754R default).
        Parameters:
        properties - The property bag.
        Returns:
        A MathContext. Never null.
      • getMathContextOr34Digits

        public static java.math.MathContext getMathContextOr34Digits​(DecimalFormatProperties properties)
        Gets the user-specified math context out of the property bag. If there is none, falls back to a math context with 34 digits of precision (the 128-bit IEEE 754R default) and the user-specified rounding mode, which defaults to HALF_EVEN (the IEEE 754R default).
        Parameters:
        properties - The property bag.
        Returns:
        A MathContext. Never null.
      • mathContextUnlimited

        public static java.math.MathContext mathContextUnlimited​(java.math.RoundingMode roundingMode)
        Gets a MathContext with unlimited precision and the specified RoundingMode. Equivalent to "new MathContext(0, roundingMode)", but pulls from a singleton to prevent object thrashing.
        Parameters:
        roundingMode - The RoundingMode to use.
        Returns:
        The corresponding MathContext.