Class FloatToDecimal

java.lang.Object
tools.jackson.core.io.schubfach.FloatToDecimal
public final class FloatToDecimal extends Object
This class exposes a method to render a float as a string.

  • Field Details

  • Constructor Details

    • FloatToDecimal

      private FloatToDecimal()

  • Method Details

    • toString

      public static String toString(float v)
      Returns a string rendering of the float argument.

      The characters of the result are all drawn from the ASCII set.

      • Any NaN, whether quiet or signaling, is rendered as "NaN", regardless of the sign bit.
      • The infinities +∞ and -∞ are rendered as "Infinity" and "-Infinity", respectively.
      • The positive and negative zeroes are rendered as "0.0" and "-0.0", respectively.
      • A finite negative v is rendered as the sign '-' followed by the rendering of the magnitude -v.
      • A finite positive v is rendered in two stages:
        • Selection of a decimal: A well-defined decimal dv is selected to represent v.
        • Formatting as a string: The decimal dv is formatted as a string, either in plain or in computerized scientific notation, depending on its value.

      A decimal is a number of the form d×10i for some (unique) integers d > 0 and i such that d is not a multiple of 10. These integers are the significand and the exponent, respectively, of the decimal. The length of the decimal is the (unique) integer n meeting 10n-1 ≤ d < 10n.

      The decimal dv for a finite positive v is defined as follows:

      • Let R be the set of all decimals that round to v according to the usual round-to-closest rule of IEEE 754 floating-point arithmetic.
      • Let m be the minimal length over all decimals in R.
      • When m ≥ 2, let T be the set of all decimals in R with length m. Otherwise, let T be the set of all decimals in R with length 1 or 2.
      • Define dv as the decimal in T that is closest to v. Or if there are two such decimals in T, select the one with the even significand (there is exactly one).

      The (uniquely) selected decimal dv is then formatted.

      Let d, i and n be the significand, exponent and length of dv, respectively. Further, let e = n + i - 1 and let d1…dn be the usual decimal expansion of the significand. Note that d1 ≠ 0 ≠ dn.

      • Case -3 ≤ e < 0: dv is formatted as 0.0…0d1…dn, where there are exactly -(n + i) zeroes between the decimal point and d1. For example, 123 × 10-4 is formatted as 0.0123.
      • Case 0 ≤ e < 7:
        • Subcase i ≥ 0: dv is formatted as d1…dn0…0.0, where there are exactly i zeroes between dn and the decimal point. For example, 123 × 102 is formatted as 12300.0.
        • Subcase i < 0: dv is formatted as d1…dn+i.dn+i+1…dn. There are exactly -i digits to the right of the decimal point. For example, 123 × 10-1 is formatted as 12.3.
      • Case e < -3 or e ≥ 7: computerized scientific notation is used to format dv. Here e is formatted as by Integer.toString(int).
        • Subcase n = 1: dv is formatted as d1.0Ee. For example, 1 × 1023 is formatted as 1.0E23.
        • Subcase n > 1: dv is formatted as d1.d2…dnEe. For example, 123 × 10-21 is formatted as 1.23E-19.
      Parameters:
      v - the float to be rendered.
      Returns:
      a string rendering of the argument.

    • toDecimalString

      private String toDecimalString(float v)

    • toDecimal

      private int toDecimal(float v)

    • toDecimal

      private int toDecimal(int q, int c, int dk)

    • rop

      private static int rop(long g, long cp)

    • toChars

      private int toChars(int f, int e)

    • toChars1

      private int toChars1(int h, int l, int e)

    • toChars2

      private int toChars2(int h, int l, int e)

    • toChars3

      private int toChars3(int h, int l, int e)

    • append8Digits

      private void append8Digits(int m)

    • removeTrailingZeroes

      private void removeTrailingZeroes()

    • y

      private int y(int a)

    • exponent

      private void exponent(int e)

    • append

      private void append(int c)

    • appendDigit

      private void appendDigit(int d)

    • charsToString

      private String charsToString()