Class RoundingUtils

java.lang.Object
com.ibm.icu.impl.number.RoundingUtils

public class RoundingUtils extends Object
  • Field Details

    • SECTION_LOWER

      public static final int SECTION_LOWER
      See Also:
    • SECTION_MIDPOINT

      public static final int SECTION_MIDPOINT
      See Also:
    • SECTION_UPPER

      public static final int SECTION_UPPER
      See Also:
    • DEFAULT_ROUNDING_MODE

      public static final 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:
    • MATH_CONTEXT_BY_ROUNDING_MODE_UNLIMITED

      private static final MathContext[] MATH_CONTEXT_BY_ROUNDING_MODE_UNLIMITED
    • MATH_CONTEXT_BY_ROUNDING_MODE_34_DIGITS

      private static final MathContext[] MATH_CONTEXT_BY_ROUNDING_MODE_34_DIGITS
    • DEFAULT_MATH_CONTEXT_UNLIMITED

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

      public static final MathContext DEFAULT_MATH_CONTEXT_34_DIGITS
      The default MathContext, 34-digit version.
  • Constructor Details

    • RoundingUtils

      public RoundingUtils()
  • Method Details

    • getRoundingDirection

      public static boolean getRoundingDirection(boolean isEven, boolean isNegative, int section, int roundingMode, 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 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 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 MathContext mathContextUnlimited(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.
    • scaleFromProperties

      public static Scale scaleFromProperties(DecimalFormatProperties properties)
    • getPluralSafe

      public static StandardPlural getPluralSafe(Precision rounder, PluralRules rules, DecimalQuantity dq)
      Computes the plural form after copying the number and applying rounding rules.