com.fasterxml.jackson.core.io.schubfach

## Class FloatToDecimal

• public final class FloatToDecimal
extends Object
This class exposes a method to render a float as a string.
Author:
Raffaello Giulietti

• ### Method Detail

• #### 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-1d < 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 d1dn be the usual decimal expansion of the significand. Note that d1 ≠ 0 ≠ dn.

• Case -3 ≤ e < 0: dv is formatted as 0.00d1dn, 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 d1dn00.0, 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 d1dn+i.dn+i+1dn. 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.d2dnEe. 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.
• #### appendTo

public static Appendable appendTo(float v,
Appendable app)
throws IOException
Appends the rendering of the v to app.

The outcome is the same as if v were first rendered and the resulting string were then appended to app.

Parameters:
v - the float whose rendering is appended.
app - the Appendable to append to.
Throws:
IOException - If an I/O error occurs