https://openjdk.java.net/ 
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package java.lang;

import sun.misc.FloatingDecimal;
import sun.misc.FpUtils;
import sun.misc.FloatConsts;
import sun.misc.DoubleConsts;


The Float class wraps a value of primitive type float in an object. An object of type Float contains a single field whose type is float. 
In addition, this class provides several methods for converting a float to a String and a String to a float, as well as other constants and methods useful when dealing with a float. 
Author: Lee Boynton,  Arthur van Hoff,  Joseph D. Darcy
Since:JDK1.0
/**
 * The {@code Float} class wraps a value of primitive type
 * {@code float} in an object. An object of type
 * {@code Float} contains a single field whose type is
 * {@code float}.
 *
 * <p>In addition, this class provides several methods for converting a
 * {@code float} to a {@code String} and a
 * {@code String} to a {@code float}, as well as other
 * constants and methods useful when dealing with a
 * {@code float}.
 *
 * @author  Lee Boynton
 * @author  Arthur van Hoff
 * @author  Joseph D. Darcy
 * @since JDK1.0
 */
public final class Float extends Number implements Comparable<Float> {
    
A constant holding the positive infinity of type float. It is equal to the value returned by Float.intBitsToFloat(0x7f800000). 
/**
     * A constant holding the positive infinity of type
     * {@code float}. It is equal to the value returned by
     * {@code Float.intBitsToFloat(0x7f800000)}.
     */
    public static final float POSITIVE_INFINITY = 1.0f / 0.0f;

    
A constant holding the negative infinity of type float. It is equal to the value returned by Float.intBitsToFloat(0xff800000). 
/**
     * A constant holding the negative infinity of type
     * {@code float}. It is equal to the value returned by
     * {@code Float.intBitsToFloat(0xff800000)}.
     */
    public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;

    
A constant holding a Not-a-Number (NaN) value of type float. It is equivalent to the value returned by Float.intBitsToFloat(0x7fc00000). 
/**
     * A constant holding a Not-a-Number (NaN) value of type
     * {@code float}.  It is equivalent to the value returned by
     * {@code Float.intBitsToFloat(0x7fc00000)}.
     */
    public static final float NaN = 0.0f / 0.0f;

    
A constant holding the largest positive finite value of type float, (2-2-23)·2127. It is equal to the hexadecimal floating-point literal 0x1.fffffeP+127f and also equal to Float.intBitsToFloat(0x7f7fffff). 
/**
     * A constant holding the largest positive finite value of type
     * {@code float}, (2-2<sup>-23</sup>)&middot;2<sup>127</sup>.
     * It is equal to the hexadecimal floating-point literal
     * {@code 0x1.fffffeP+127f} and also equal to
     * {@code Float.intBitsToFloat(0x7f7fffff)}.
     */
    public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f

    
A constant holding the smallest positive normal value of type float, 2-126. It is equal to the hexadecimal floating-point literal 0x1.0p-126f and also equal to Float.intBitsToFloat(0x00800000). 
Since:1.6
/**
     * A constant holding the smallest positive normal value of type
     * {@code float}, 2<sup>-126</sup>.  It is equal to the
     * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
     * equal to {@code Float.intBitsToFloat(0x00800000)}.
     *
     * @since 1.6
     */
    public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f

    
A constant holding the smallest positive nonzero value of type float, 2-149. It is equal to the hexadecimal floating-point literal 0x0.000002P-126f and also equal to Float.intBitsToFloat(0x1). 
/**
     * A constant holding the smallest positive nonzero value of type
     * {@code float}, 2<sup>-149</sup>. It is equal to the
     * hexadecimal floating-point literal {@code 0x0.000002P-126f}
     * and also equal to {@code Float.intBitsToFloat(0x1)}.
     */
    public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f

    
Maximum exponent a finite float variable may have. It is equal to the value returned by 
Math.getExponent(Float.MAX_VALUE). 
Since:1.6
/**
     * Maximum exponent a finite {@code float} variable may have.  It
     * is equal to the value returned by {@code
     * Math.getExponent(Float.MAX_VALUE)}.
     *
     * @since 1.6
     */
    public static final int MAX_EXPONENT = 127;

    
Minimum exponent a normalized float variable may have. It is equal to the value returned by 
Math.getExponent(Float.MIN_NORMAL). 
Since:1.6
/**
     * Minimum exponent a normalized {@code float} variable may have.
     * It is equal to the value returned by {@code
     * Math.getExponent(Float.MIN_NORMAL)}.
     *
     * @since 1.6
     */
    public static final int MIN_EXPONENT = -126;

    
The number of bits used to represent a float value. 
Since:1.5
/**
     * The number of bits used to represent a {@code float} value.
     *
     * @since 1.5
     */
    public static final int SIZE = 32;

    
The Class instance representing the primitive type float. 
Since:JDK1.1
/**
     * The {@code Class} instance representing the primitive type
     * {@code float}.
     *
     * @since JDK1.1
     */
    public static final Class<Float> TYPE = Class.getPrimitiveClass("float");

    
Returns a string representation of the float argument. All characters mentioned below are ASCII characters. 
    

  • If the argument is NaN, the result is the string "NaN". 
  • Otherwise, the result is a string that represents the sign and magnitude (absolute value) of the argument. If the sign is negative, the first character of the result is '-' ('\u002D'); if the sign is
    positive, no sign character appears in the result. As for
    the magnitude m:

      

    • If m is infinity, it is represented by the characters "Infinity"; thus, positive infinity produces the result "Infinity" and negative infinity produces the result "-Infinity". 
    • If m is zero, it is represented by the characters "0.0"; thus, negative zero produces the result "-0.0" and positive zero produces the result "0.0". 
    •  If m is greater than or equal to 10-3 but
     less than 107, then it is represented as the
     integer part of m, in decimal form with no leading zeroes, followed by '.' ('\u002E'), followed by one or more
     decimal digits representing the fractional part of
     m.

    •  If m is less than 10-3 or greater than or
     equal to 107, then it is represented in
     so-called "computerized scientific notation." Let n
     be the unique integer such that 10n ≤
     m < 10n+1; then let a
     be the mathematically exact quotient of m and
     10n so that 1 ≤ a < 10. The magnitude is then represented as the integer part of a, as a single decimal digit, followed by '.' ('\u002E'), followed by
     decimal digits representing the fractional part of
     a, followed by the letter 'E' ('\u0045'), followed by a representation
     of n as a decimal integer, as produced by the method Integer.toString(int). 
    


How many digits must be printed for the fractional part of
m or a? There must be at least one digit to represent the fractional part, and beyond that as many, but only as many, more digits as are needed to uniquely distinguish the argument value from adjacent values of type float. That is, suppose that x is the
exact mathematical value represented by the decimal
representation produced by this method for a finite nonzero
argument f. Then f must be the float value nearest to x; or, if two float values are equally close to x, then f must be one of
them and the least significant bit of the significand of
f must be 0. 
To create localized string representations of a floating-point value, use subclasses of NumberFormat. 
Params:
  • f –   the float to be converted.
Returns:a string representation of the argument.
/**
     * Returns a string representation of the {@code float}
     * argument. All characters mentioned below are ASCII characters.
     * <ul>
     * <li>If the argument is NaN, the result is the string
     * "{@code NaN}".
     * <li>Otherwise, the result is a string that represents the sign and
     *     magnitude (absolute value) of the argument. If the sign is
     *     negative, the first character of the result is
     *     '{@code -}' (<code>'&#92;u002D'</code>); if the sign is
     *     positive, no sign character appears in the result. As for
     *     the magnitude <i>m</i>:
     * <ul>
     * <li>If <i>m</i> is infinity, it is represented by the characters
     *     {@code "Infinity"}; thus, positive infinity produces
     *     the result {@code "Infinity"} and negative infinity
     *     produces the result {@code "-Infinity"}.
     * <li>If <i>m</i> is zero, it is represented by the characters
     *     {@code "0.0"}; thus, negative zero produces the result
     *     {@code "-0.0"} and positive zero produces the result
     *     {@code "0.0"}.
     * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
     *      less than 10<sup>7</sup>, then it is represented as the
     *      integer part of <i>m</i>, in decimal form with no leading
     *      zeroes, followed by '{@code .}'
     *      (<code>'&#92;u002E'</code>), followed by one or more
     *      decimal digits representing the fractional part of
     *      <i>m</i>.
     * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
     *      equal to 10<sup>7</sup>, then it is represented in
     *      so-called "computerized scientific notation." Let <i>n</i>
     *      be the unique integer such that 10<sup><i>n</i> </sup>&le;
     *      <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
     *      be the mathematically exact quotient of <i>m</i> and
     *      10<sup><i>n</i></sup> so that 1 &le; <i>a</i> {@literal <} 10.
     *      The magnitude is then represented as the integer part of
     *      <i>a</i>, as a single decimal digit, followed by
     *      '{@code .}' (<code>'&#92;u002E'</code>), followed by
     *      decimal digits representing the fractional part of
     *      <i>a</i>, followed by the letter '{@code E}'
     *      (<code>'&#92;u0045'</code>), followed by a representation
     *      of <i>n</i> as a decimal integer, as produced by the
     *      method {@link java.lang.Integer#toString(int)}.
     *
     * </ul>
     * </ul>
     * How many digits must be printed for the fractional part of
     * <i>m</i> or <i>a</i>? There must be at least one digit
     * to represent the fractional part, and beyond that as many, but
     * only as many, more digits as are needed to uniquely distinguish
     * the argument value from adjacent values of type
     * {@code float}. That is, suppose that <i>x</i> is the
     * exact mathematical value represented by the decimal
     * representation produced by this method for a finite nonzero
     * argument <i>f</i>. Then <i>f</i> must be the {@code float}
     * value nearest to <i>x</i>; or, if two {@code float} values are
     * equally close to <i>x</i>, then <i>f</i> must be one of
     * them and the least significant bit of the significand of
     * <i>f</i> must be {@code 0}.
     *
     * <p>To create localized string representations of a floating-point
     * value, use subclasses of {@link java.text.NumberFormat}.
     *
     * @param   f   the float to be converted.
     * @return a string representation of the argument.
     */
    public static String toString(float f) {
        return new FloatingDecimal(f).toJavaFormatString();
    }

    
Returns a hexadecimal string representation of the float argument. All characters mentioned below are ASCII characters. 
    

  • If the argument is NaN, the result is the string "NaN". 
  • Otherwise, the result is a string that represents the sign and magnitude (absolute value) of the argument. If the sign is negative, the first character of the result is '-' ('\u002D'); if the sign is positive, no sign character
appears in the result. As for the magnitude m:

      

    • If m is infinity, it is represented by the string "Infinity"; thus, positive infinity produces the result "Infinity" and negative infinity produces the result "-Infinity". 
    • If m is zero, it is represented by the string "0x0.0p0"; thus, negative zero produces the result "-0x0.0p0" and positive zero produces the result "0x0.0p0". 
    • If m is a float value with a normalized representation, substrings are used to represent the significand and exponent fields. The significand is represented by the characters "0x1." followed by a lowercase hexadecimal representation of the rest of the significand as a fraction. Trailing zeros in the hexadecimal representation are removed unless all the digits are zero, in which case a single zero is used. Next, the exponent is represented by "p" followed by a decimal string of the unbiased exponent as if produced by a call to Integer.toString on the exponent value. 
    • If m is a float value with a subnormal representation, the significand is represented by the characters "0x0." followed by a hexadecimal representation of the rest of the significand as a fraction. Trailing zeros in the hexadecimal representation are removed. Next, the exponent is represented by "p-126". Note that there must be at least one nonzero digit in a subnormal significand. 
    





Examples


Floating-point ValueHexadecimal String

1.0 0x1.0p0

-1.0        -0x1.0p0

2.0 0x1.0p1

3.0 0x1.8p1

0.5 0x1.0p-1

0.25        0x1.0p-2

Float.MAX_VALUE
    0x1.fffffep127

Minimum Normal Value
    0x1.0p-126

Maximum Subnormal Value
    0x0.fffffep-126

Float.MIN_VALUE
    0x0.000002p-126



Author:Joseph D. Darcy
Params:
  • f –  the float to be converted.
Returns:a hex string representation of the argument.
Since:1.5
/**
     * Returns a hexadecimal string representation of the
     * {@code float} argument. All characters mentioned below are
     * ASCII characters.
     *
     * <ul>
     * <li>If the argument is NaN, the result is the string
     *     "{@code NaN}".
     * <li>Otherwise, the result is a string that represents the sign and
     * magnitude (absolute value) of the argument. If the sign is negative,
     * the first character of the result is '{@code -}'
     * (<code>'&#92;u002D'</code>); if the sign is positive, no sign character
     * appears in the result. As for the magnitude <i>m</i>:
     *
     * <ul>
     * <li>If <i>m</i> is infinity, it is represented by the string
     * {@code "Infinity"}; thus, positive infinity produces the
     * result {@code "Infinity"} and negative infinity produces
     * the result {@code "-Infinity"}.
     *
     * <li>If <i>m</i> is zero, it is represented by the string
     * {@code "0x0.0p0"}; thus, negative zero produces the result
     * {@code "-0x0.0p0"} and positive zero produces the result
     * {@code "0x0.0p0"}.
     *
     * <li>If <i>m</i> is a {@code float} value with a
     * normalized representation, substrings are used to represent the
     * significand and exponent fields.  The significand is
     * represented by the characters {@code "0x1."}
     * followed by a lowercase hexadecimal representation of the rest
     * of the significand as a fraction.  Trailing zeros in the
     * hexadecimal representation are removed unless all the digits
     * are zero, in which case a single zero is used. Next, the
     * exponent is represented by {@code "p"} followed
     * by a decimal string of the unbiased exponent as if produced by
     * a call to {@link Integer#toString(int) Integer.toString} on the
     * exponent value.
     *
     * <li>If <i>m</i> is a {@code float} value with a subnormal
     * representation, the significand is represented by the
     * characters {@code "0x0."} followed by a
     * hexadecimal representation of the rest of the significand as a
     * fraction.  Trailing zeros in the hexadecimal representation are
     * removed. Next, the exponent is represented by
     * {@code "p-126"}.  Note that there must be at
     * least one nonzero digit in a subnormal significand.
     *
     * </ul>
     *
     * </ul>
     *
     * <table border>
     * <caption><h3>Examples</h3></caption>
     * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
     * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
     * <tr><td>{@code -1.0}</td>        <td>{@code -0x1.0p0}</td>
     * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
     * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
     * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
     * <tr><td>{@code 0.25}</td>        <td>{@code 0x1.0p-2}</td>
     * <tr><td>{@code Float.MAX_VALUE}</td>
     *     <td>{@code 0x1.fffffep127}</td>
     * <tr><td>{@code Minimum Normal Value}</td>
     *     <td>{@code 0x1.0p-126}</td>
     * <tr><td>{@code Maximum Subnormal Value}</td>
     *     <td>{@code 0x0.fffffep-126}</td>
     * <tr><td>{@code Float.MIN_VALUE}</td>
     *     <td>{@code 0x0.000002p-126}</td>
     * </table>
     * @param   f   the {@code float} to be converted.
     * @return a hex string representation of the argument.
     * @since 1.5
     * @author Joseph D. Darcy
     */
    public static String toHexString(float f) {
        if (Math.abs(f) < FloatConsts.MIN_NORMAL
            &&  f != 0.0f ) {// float subnormal
            // Adjust exponent to create subnormal double, then
            // replace subnormal double exponent with subnormal float
            // exponent
            String s = Double.toHexString(FpUtils.scalb((double)f,
                                                        /* -1022+126 */
                                                        DoubleConsts.MIN_EXPONENT-
                                                        FloatConsts.MIN_EXPONENT));
            return s.replaceFirst("p-1022$", "p-126");
        }
        else // double string will be the same as float string
            return Double.toHexString(f);
    }

    
Returns a Float object holding the float value represented by the argument string s. 
If s is null, then a NullPointerException is thrown. 
Leading and trailing whitespace characters in s are ignored. Whitespace is removed as if by the String.trim method; that is, both ASCII space and control characters are removed. The rest of s should constitute a FloatValue as described by the lexical
syntax rules:





FloatValue:

Signopt NaN 
Signopt Infinity 
Signopt FloatingPointLiteral

Signopt HexFloatingPointLiteral

SignedInteger







HexFloatingPointLiteral:

 HexSignificand BinaryExponent FloatTypeSuffixopt







HexSignificand:

HexNumeral

HexNumeral . 
0x HexDigitsopt
    . HexDigits

0X HexDigitsopt
    . HexDigits







BinaryExponent:

BinaryExponentIndicator SignedInteger







BinaryExponentIndicator:

p 
P 



where Sign, FloatingPointLiteral,
HexNumeral, HexDigits, SignedInteger and
FloatTypeSuffix are as defined in the lexical structure
sections of the Java Language
Specification. If s does not have the form of a FloatValue, then a NumberFormatException is thrown. Otherwise, s is regarded as representing an exact decimal value in the usual "computerized scientific notation" or as an exact hexadecimal value; this exact numerical value is then conceptually converted to an "infinitely precise" binary value that is then rounded to type float by the usual round-to-nearest rule of IEEE 754 floating-point arithmetic, which includes preserving the sign of a zero value. Finally, a Float object representing this float value is returned. 
To interpret localized string representations of a floating-point value, use subclasses of NumberFormat. 
Note that trailing format specifiers, specifiers that determine the type of a floating-point literal (1.0f is a float value; 1.0d is a double value), do not influence the results of this method. In other words, the numerical value of the input string is converted directly to the target floating-point type. In general, the two-step sequence of conversions, string to double followed by double to float, is not equivalent to converting a string directly to float. For example, if first converted to an intermediate double and then to float, the string
 "1.00000017881393421514957253748434595763683319091796875001d"
 results in the float value 1.0000002f; if the string is converted directly to float, 1.0000001f results.

To avoid calling this method on an invalid string and having a NumberFormatException be thrown, the documentation for Double.valueOf lists a regular expression which can be used to screen the input. 
Params:
  • s –   the string to be parsed.
Throws:
Returns: a Float object holding the value represented by the String argument.
/**
     * Returns a {@code Float} object holding the
     * {@code float} value represented by the argument string
     * {@code s}.
     *
     * <p>If {@code s} is {@code null}, then a
     * {@code NullPointerException} is thrown.
     *
     * <p>Leading and trailing whitespace characters in {@code s}
     * are ignored.  Whitespace is removed as if by the {@link
     * String#trim} method; that is, both ASCII space and control
     * characters are removed. The rest of {@code s} should
     * constitute a <i>FloatValue</i> as described by the lexical
     * syntax rules:
     *
     * <blockquote>
     * <dl>
     * <dt><i>FloatValue:</i>
     * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
     * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
     * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
     * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
     * <dd><i>SignedInteger</i>
     * </dl>
     *
     * <p>
     *
     * <dl>
     * <dt><i>HexFloatingPointLiteral</i>:
     * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
     * </dl>
     *
     * <p>
     *
     * <dl>
     * <dt><i>HexSignificand:</i>
     * <dd><i>HexNumeral</i>
     * <dd><i>HexNumeral</i> {@code .}
     * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
     *     </i>{@code .}<i> HexDigits</i>
     * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
     *     </i>{@code .} <i>HexDigits</i>
     * </dl>
     *
     * <p>
     *
     * <dl>
     * <dt><i>BinaryExponent:</i>
     * <dd><i>BinaryExponentIndicator SignedInteger</i>
     * </dl>
     *
     * <p>
     *
     * <dl>
     * <dt><i>BinaryExponentIndicator:</i>
     * <dd>{@code p}
     * <dd>{@code P}
     * </dl>
     *
     * </blockquote>
     *
     * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
     * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
     * <i>FloatTypeSuffix</i> are as defined in the lexical structure
     * sections of the <a
     * href="http://java.sun.com/docs/books/jls/html/">Java Language
     * Specification</a>. If {@code s} does not have the form of
     * a <i>FloatValue</i>, then a {@code NumberFormatException}
     * is thrown. Otherwise, {@code s} is regarded as
     * representing an exact decimal value in the usual
     * "computerized scientific notation" or as an exact
     * hexadecimal value; this exact numerical value is then
     * conceptually converted to an "infinitely precise"
     * binary value that is then rounded to type {@code float}
     * by the usual round-to-nearest rule of IEEE 754 floating-point
     * arithmetic, which includes preserving the sign of a zero
     * value. Finally, a {@code Float} object representing this
     * {@code float} value is returned.
     *
     * <p>To interpret localized string representations of a
     * floating-point value, use subclasses of {@link
     * java.text.NumberFormat}.
     *
     * <p>Note that trailing format specifiers, specifiers that
     * determine the type of a floating-point literal
     * ({@code 1.0f} is a {@code float} value;
     * {@code 1.0d} is a {@code double} value), do
     * <em>not</em> influence the results of this method.  In other
     * words, the numerical value of the input string is converted
     * directly to the target floating-point type.  In general, the
     * two-step sequence of conversions, string to {@code double}
     * followed by {@code double} to {@code float}, is
     * <em>not</em> equivalent to converting a string directly to
     * {@code float}.  For example, if first converted to an
     * intermediate {@code double} and then to
     * {@code float}, the string<br>
     * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
     * results in the {@code float} value
     * {@code 1.0000002f}; if the string is converted directly to
     * {@code float}, <code>1.000000<b>1</b>f</code> results.
     *
     * <p>To avoid calling this method on an invalid string and having
     * a {@code NumberFormatException} be thrown, the documentation
     * for {@link Double#valueOf Double.valueOf} lists a regular
     * expression which can be used to screen the input.
     *
     * @param   s   the string to be parsed.
     * @return  a {@code Float} object holding the value
     *          represented by the {@code String} argument.
     * @throws  NumberFormatException  if the string does not contain a
     *          parsable number.
     */
    public static Float valueOf(String s) throws NumberFormatException {
        return new Float(FloatingDecimal.readJavaFormatString(s).floatValue());
    }

    
Returns a Float instance representing the specified float value. If a new Float instance is not required, this method should generally be used in preference to the constructor Float(float), as this method is likely to yield significantly better space and time performance by caching frequently requested values. 
Params:
  • f – a float value.
Returns:a Float instance representing f.
Since: 1.5
/**
     * Returns a {@code Float} instance representing the specified
     * {@code float} value.
     * If a new {@code Float} instance is not required, this method
     * should generally be used in preference to the constructor
     * {@link #Float(float)}, as this method is likely to yield
     * significantly better space and time performance by caching
     * frequently requested values.
     *
     * @param  f a float value.
     * @return a {@code Float} instance representing {@code f}.
     * @since  1.5
     */
    public static Float valueOf(float f) {
        return new Float(f);
    }

    
Returns a new float initialized to the value represented by the specified String, as performed by the valueOf method of class Float. 
Params:
  • s –   the string to be parsed.
Throws:
See Also:
Returns:the float value represented by the string argument.
Since:1.2
/**
     * Returns a new {@code float} initialized to the value
     * represented by the specified {@code String}, as performed
     * by the {@code valueOf} method of class {@code Float}.
     *
     * @param      s   the string to be parsed.
     * @return the {@code float} value represented by the string
     *         argument.
     * @throws  NumberFormatException  if the string does not contain a
     *               parsable {@code float}.
     * @see        java.lang.Float#valueOf(String)
     * @since 1.2
     */
    public static float parseFloat(String s) throws NumberFormatException {
        return FloatingDecimal.readJavaFormatString(s).floatValue();
    }

    
Returns true if the specified number is a Not-a-Number (NaN) value, false otherwise. 
Params:
  • v –   the value to be tested.
Returns: true if the argument is NaN; false otherwise.
/**
     * Returns {@code true} if the specified number is a
     * Not-a-Number (NaN) value, {@code false} otherwise.
     *
     * @param   v   the value to be tested.
     * @return  {@code true} if the argument is NaN;
     *          {@code false} otherwise.
     */
    static public boolean isNaN(float v) {
        return (v != v);
    }

    
Returns true if the specified number is infinitely large in magnitude, false otherwise. 
Params:
  • v –   the value to be tested.
Returns: true if the argument is positive infinity or negative infinity; false otherwise.
/**
     * Returns {@code true} if the specified number is infinitely
     * large in magnitude, {@code false} otherwise.
     *
     * @param   v   the value to be tested.
     * @return  {@code true} if the argument is positive infinity or
     *          negative infinity; {@code false} otherwise.
     */
    static public boolean isInfinite(float v) {
        return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
    }

    
The value of the Float.

@serial
/**
     * The value of the Float.
     *
     * @serial
     */
    private final float value;

    
Constructs a newly allocated Float object that represents the primitive float argument. 
Params:
  • value –  the value to be represented by the Float.
/**
     * Constructs a newly allocated {@code Float} object that
     * represents the primitive {@code float} argument.
     *
     * @param   value   the value to be represented by the {@code Float}.
     */
    public Float(float value) {
        this.value = value;
    }

    
Constructs a newly allocated Float object that represents the argument converted to type float. 
Params:
  • value –  the value to be represented by the Float.
/**
     * Constructs a newly allocated {@code Float} object that
     * represents the argument converted to type {@code float}.
     *
     * @param   value   the value to be represented by the {@code Float}.
     */
    public Float(double value) {
        this.value = (float)value;
    }

    
Constructs a newly allocated Float object that represents the floating-point value of type float represented by the string. The string is converted to a float value as if by the valueOf method. 
Params:
  • s –  a string to be converted to a Float.
Throws:
See Also:
/**
     * Constructs a newly allocated {@code Float} object that
     * represents the floating-point value of type {@code float}
     * represented by the string. The string is converted to a
     * {@code float} value as if by the {@code valueOf} method.
     *
     * @param      s   a string to be converted to a {@code Float}.
     * @throws  NumberFormatException  if the string does not contain a
     *               parsable number.
     * @see        java.lang.Float#valueOf(java.lang.String)
     */
    public Float(String s) throws NumberFormatException {
        // REMIND: this is inefficient
        this(valueOf(s).floatValue());
    }

    
Returns true if this Float value is a Not-a-Number (NaN), false otherwise. 
Returns: true if the value represented by this object is NaN; false otherwise.
/**
     * Returns {@code true} if this {@code Float} value is a
     * Not-a-Number (NaN), {@code false} otherwise.
     *
     * @return  {@code true} if the value represented by this object is
     *          NaN; {@code false} otherwise.
     */
    public boolean isNaN() {
        return isNaN(value);
    }

    
Returns true if this Float value is infinitely large in magnitude, false otherwise. 
Returns: true if the value represented by this object is positive infinity or negative infinity; false otherwise.
/**
     * Returns {@code true} if this {@code Float} value is
     * infinitely large in magnitude, {@code false} otherwise.
     *
     * @return  {@code true} if the value represented by this object is
     *          positive infinity or negative infinity;
     *          {@code false} otherwise.
     */
    public boolean isInfinite() {
        return isInfinite(value);
    }

    
Returns a string representation of this Float object. The primitive float value represented by this object is converted to a String exactly as if by the method toString of one argument. 
See Also:
Returns: a String representation of this object.
/**
     * Returns a string representation of this {@code Float} object.
     * The primitive {@code float} value represented by this object
     * is converted to a {@code String} exactly as if by the method
     * {@code toString} of one argument.
     *
     * @return  a {@code String} representation of this object.
     * @see java.lang.Float#toString(float)
     */
    public String toString() {
        return String.valueOf(value);
    }

    
Returns the value of this Float as a byte (by casting to a byte). 
Returns: the float value represented by this object converted to type byte
/**
     * Returns the value of this {@code Float} as a {@code byte} (by
     * casting to a {@code byte}).
     *
     * @return  the {@code float} value represented by this object
     *          converted to type {@code byte}
     */
    public byte byteValue() {
        return (byte)value;
    }

    
Returns the value of this Float as a short (by casting to a short). 
Returns: the float value represented by this object converted to type short
Since:JDK1.1
/**
     * Returns the value of this {@code Float} as a {@code short} (by
     * casting to a {@code short}).
     *
     * @return  the {@code float} value represented by this object
     *          converted to type {@code short}
     * @since JDK1.1
     */
    public short shortValue() {
        return (short)value;
    }

    
Returns the value of this Float as an int (by casting to type int). 
Returns: the float value represented by this object converted to type int
/**
     * Returns the value of this {@code Float} as an {@code int} (by
     * casting to type {@code int}).
     *
     * @return  the {@code float} value represented by this object
     *          converted to type {@code int}
     */
    public int intValue() {
        return (int)value;
    }

    
Returns value of this Float as a long (by casting to type long). 
Returns: the float value represented by this object converted to type long
/**
     * Returns value of this {@code Float} as a {@code long} (by
     * casting to type {@code long}).
     *
     * @return  the {@code float} value represented by this object
     *          converted to type {@code long}
     */
    public long longValue() {
        return (long)value;
    }

    
Returns the float value of this Float object. 
Returns:the float value represented by this object
/**
     * Returns the {@code float} value of this {@code Float} object.
     *
     * @return the {@code float} value represented by this object
     */
    public float floatValue() {
        return value;
    }

    
Returns the double value of this Float object. 
Returns:the float value represented by this object is converted to type double and the result of the conversion is returned.
/**
     * Returns the {@code double} value of this {@code Float} object.
     *
     * @return the {@code float} value represented by this
     *         object is converted to type {@code double} and the
     *         result of the conversion is returned.
     */
    public double doubleValue() {
        return (double)value;
    }

    
Returns a hash code for this Float object. The result is the integer bit representation, exactly as produced by the method floatToIntBits(float), of the primitive float value represented by this Float object. 
Returns:a hash code value for this object.
/**
     * Returns a hash code for this {@code Float} object. The
     * result is the integer bit representation, exactly as produced
     * by the method {@link #floatToIntBits(float)}, of the primitive
     * {@code float} value represented by this {@code Float}
     * object.
     *
     * @return a hash code value for this object.
     */
    public int hashCode() {
        return floatToIntBits(value);
    }

    
Compares this object against the specified object. The result is true if and only if the argument is not null and is a Float object that represents a float with the same value as the float represented by this object. For this purpose, two float values are considered to be the same if and only if the method floatToIntBits(float) returns the identical int value when applied to each. 
Note that in most cases, for two instances of class Float, f1 and f2, the value of f1.equals(f2) is true if and only if 
  f1.floatValue() == f2.floatValue()



also has the value true. However, there are two exceptions: 
    

  • If f1 and f2 both represent Float.NaN, then the equals method returns true, even though Float.NaN==Float.NaN has the value false. 
  • If f1 represents +0.0f while f2 represents -0.0f, or vice versa, the equal test has the value false, even though 0.0f==-0.0f has the value true. 

This definition allows hash tables to operate properly.

Params:
  • obj – the object to be compared
See Also:
Returns: true if the objects are the same; false otherwise.
/**

     * Compares this object against the specified object.  The result
     * is {@code true} if and only if the argument is not
     * {@code null} and is a {@code Float} object that
     * represents a {@code float} with the same value as the
     * {@code float} represented by this object. For this
     * purpose, two {@code float} values are considered to be the
     * same if and only if the method {@link #floatToIntBits(float)}
     * returns the identical {@code int} value when applied to
     * each.
     *
     * <p>Note that in most cases, for two instances of class
     * {@code Float}, {@code f1} and {@code f2}, the value
     * of {@code f1.equals(f2)} is {@code true} if and only if
     *
     * <blockquote><pre>
     *   f1.floatValue() == f2.floatValue()
     * </pre></blockquote>
     *
     * <p>also has the value {@code true}. However, there are two exceptions:
     * <ul>
     * <li>If {@code f1} and {@code f2} both represent
     *     {@code Float.NaN}, then the {@code equals} method returns
     *     {@code true}, even though {@code Float.NaN==Float.NaN}
     *     has the value {@code false}.
     * <li>If {@code f1} represents {@code +0.0f} while
     *     {@code f2} represents {@code -0.0f}, or vice
     *     versa, the {@code equal} test has the value
     *     {@code false}, even though {@code 0.0f==-0.0f}
     *     has the value {@code true}.
     * </ul>
     *
     * This definition allows hash tables to operate properly.
     *
     * @param obj the object to be compared
     * @return  {@code true} if the objects are the same;
     *          {@code false} otherwise.
     * @see java.lang.Float#floatToIntBits(float)
     */
    public boolean equals(Object obj) {
        return (obj instanceof Float)
               && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
    }

    
Returns a representation of the specified floating-point value
according to the IEEE 754 floating-point "single format" bit
layout.

Bit 31 (the bit that is selected by the mask 0x80000000) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask 0x7f800000) represent the exponent. Bits 22-0 (the bits that are selected by the mask 0x007fffff) represent the significand (sometimes called the mantissa) of the floating-point number. 
If the argument is positive infinity, the result is 0x7f800000. 
If the argument is negative infinity, the result is 0xff800000. 
If the argument is NaN, the result is 0x7fc00000. 
In all cases, the result is an integer that, when given to the intBitsToFloat(int) method, will produce a floating-point value the same as the argument to floatToIntBits (except all NaN values are collapsed to a single "canonical" NaN value). 
Params:
  • value –   a floating-point number.
Returns:the bits that represent the floating-point number.
/**
     * Returns a representation of the specified floating-point value
     * according to the IEEE 754 floating-point "single format" bit
     * layout.
     *
     * <p>Bit 31 (the bit that is selected by the mask
     * {@code 0x80000000}) represents the sign of the floating-point
     * number.
     * Bits 30-23 (the bits that are selected by the mask
     * {@code 0x7f800000}) represent the exponent.
     * Bits 22-0 (the bits that are selected by the mask
     * {@code 0x007fffff}) represent the significand (sometimes called
     * the mantissa) of the floating-point number.
     *
     * <p>If the argument is positive infinity, the result is
     * {@code 0x7f800000}.
     *
     * <p>If the argument is negative infinity, the result is
     * {@code 0xff800000}.
     *
     * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
     *
     * <p>In all cases, the result is an integer that, when given to the
     * {@link #intBitsToFloat(int)} method, will produce a floating-point
     * value the same as the argument to {@code floatToIntBits}
     * (except all NaN values are collapsed to a single
     * "canonical" NaN value).
     *
     * @param   value   a floating-point number.
     * @return the bits that represent the floating-point number.
     */
    public static int floatToIntBits(float value) {
        int result = floatToRawIntBits(value);
        // Check for NaN based on values of bit fields, maximum
        // exponent and nonzero significand.
        if ( ((result & FloatConsts.EXP_BIT_MASK) ==
              FloatConsts.EXP_BIT_MASK) &&
             (result & FloatConsts.SIGNIF_BIT_MASK) != 0)
            result = 0x7fc00000;
        return result;
    }

    
Returns a representation of the specified floating-point value
according to the IEEE 754 floating-point "single format" bit
layout, preserving Not-a-Number (NaN) values.

Bit 31 (the bit that is selected by the mask 0x80000000) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask 0x7f800000) represent the exponent. Bits 22-0 (the bits that are selected by the mask 0x007fffff) represent the significand (sometimes called the mantissa) of the floating-point number. 
If the argument is positive infinity, the result is 0x7f800000. 
If the argument is negative infinity, the result is 0xff800000. 
If the argument is NaN, the result is the integer representing the actual NaN value. Unlike the floatToIntBits method, floatToRawIntBits does not collapse all the bit patterns encoding a NaN to a single "canonical" NaN value. 
In all cases, the result is an integer that, when given to the intBitsToFloat(int) method, will produce a floating-point value the same as the argument to floatToRawIntBits. 
Params:
  • value –   a floating-point number.
Returns:the bits that represent the floating-point number.
Since:1.3
/**
     * Returns a representation of the specified floating-point value
     * according to the IEEE 754 floating-point "single format" bit
     * layout, preserving Not-a-Number (NaN) values.
     *
     * <p>Bit 31 (the bit that is selected by the mask
     * {@code 0x80000000}) represents the sign of the floating-point
     * number.
     * Bits 30-23 (the bits that are selected by the mask
     * {@code 0x7f800000}) represent the exponent.
     * Bits 22-0 (the bits that are selected by the mask
     * {@code 0x007fffff}) represent the significand (sometimes called
     * the mantissa) of the floating-point number.
     *
     * <p>If the argument is positive infinity, the result is
     * {@code 0x7f800000}.
     *
     * <p>If the argument is negative infinity, the result is
     * {@code 0xff800000}.
     *
     * <p>If the argument is NaN, the result is the integer representing
     * the actual NaN value.  Unlike the {@code floatToIntBits}
     * method, {@code floatToRawIntBits} does not collapse all the
     * bit patterns encoding a NaN to a single "canonical"
     * NaN value.
     *
     * <p>In all cases, the result is an integer that, when given to the
     * {@link #intBitsToFloat(int)} method, will produce a
     * floating-point value the same as the argument to
     * {@code floatToRawIntBits}.
     *
     * @param   value   a floating-point number.
     * @return the bits that represent the floating-point number.
     * @since 1.3
     */
    public static native int floatToRawIntBits(float value);

    
Returns the float value corresponding to a given bit representation. The argument is considered to be a representation of a floating-point value according to the IEEE 754 floating-point "single format" bit layout. 
If the argument is 0x7f800000, the result is positive infinity. 
If the argument is 0xff800000, the result is negative infinity. 
If the argument is any value in the range 0x7f800001 through 0x7fffffff or in the range 0xff800001 through 0xffffffff, the result is a NaN. No IEEE 754 floating-point operation provided by Java can distinguish between two NaN values of the same type with different bit patterns. Distinct values of NaN are only distinguishable by use of the Float.floatToRawIntBits method. 
In all other cases, let s, e, and m be three
values that can be computed from the argument:

int s = ((bits >> 31) == 0) ? 1 : -1;
int e = ((bits >> 23) & 0xff);
int m = (e == 0) ?
                (bits & 0x7fffff) << 1 :
                (bits & 0x7fffff) | 0x800000;


Then the floating-point result equals the value of the mathematical
expression s·m·2e-150.

Note that this method may not be able to return a float NaN with exactly same bit pattern as the int argument. IEEE 754 distinguishes between two kinds of NaNs, quiet NaNs and signaling NaNs. The differences between the two kinds of NaN are generally not visible in Java. Arithmetic operations on signaling NaNs turn them into quiet NaNs with a different, but often similar, bit pattern. However, on some processors merely copying a signaling NaN also performs that conversion. In particular, copying a signaling NaN to return it to the calling method may perform this conversion. So intBitsToFloat may not be able to return a float with a signaling NaN bit pattern. Consequently, for some int values, floatToRawIntBits(intBitsToFloat(start)) may not equal start. Moreover, which particular bit patterns represent signaling NaNs is platform dependent; although all NaN bit patterns, quiet or signaling, must be in the NaN range identified above. 
Params:
  • bits –   an integer.
Returns: the float floating-point value with the same bit pattern.
/**
     * Returns the {@code float} value corresponding to a given
     * bit representation.
     * The argument is considered to be a representation of a
     * floating-point value according to the IEEE 754 floating-point
     * "single format" bit layout.
     *
     * <p>If the argument is {@code 0x7f800000}, the result is positive
     * infinity.
     *
     * <p>If the argument is {@code 0xff800000}, the result is negative
     * infinity.
     *
     * <p>If the argument is any value in the range
     * {@code 0x7f800001} through {@code 0x7fffffff} or in
     * the range {@code 0xff800001} through
     * {@code 0xffffffff}, the result is a NaN.  No IEEE 754
     * floating-point operation provided by Java can distinguish
     * between two NaN values of the same type with different bit
     * patterns.  Distinct values of NaN are only distinguishable by
     * use of the {@code Float.floatToRawIntBits} method.
     *
     * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
     * values that can be computed from the argument:
     *
     * <blockquote><pre>
     * int s = ((bits &gt;&gt; 31) == 0) ? 1 : -1;
     * int e = ((bits &gt;&gt; 23) & 0xff);
     * int m = (e == 0) ?
     *                 (bits & 0x7fffff) &lt;&lt; 1 :
     *                 (bits & 0x7fffff) | 0x800000;
     * </pre></blockquote>
     *
     * Then the floating-point result equals the value of the mathematical
     * expression <i>s</i>&middot;<i>m</i>&middot;2<sup><i>e</i>-150</sup>.
     *
     * <p>Note that this method may not be able to return a
     * {@code float} NaN with exactly same bit pattern as the
     * {@code int} argument.  IEEE 754 distinguishes between two
     * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>.  The
     * differences between the two kinds of NaN are generally not
     * visible in Java.  Arithmetic operations on signaling NaNs turn
     * them into quiet NaNs with a different, but often similar, bit
     * pattern.  However, on some processors merely copying a
     * signaling NaN also performs that conversion.  In particular,
     * copying a signaling NaN to return it to the calling method may
     * perform this conversion.  So {@code intBitsToFloat} may
     * not be able to return a {@code float} with a signaling NaN
     * bit pattern.  Consequently, for some {@code int} values,
     * {@code floatToRawIntBits(intBitsToFloat(start))} may
     * <i>not</i> equal {@code start}.  Moreover, which
     * particular bit patterns represent signaling NaNs is platform
     * dependent; although all NaN bit patterns, quiet or signaling,
     * must be in the NaN range identified above.
     *
     * @param   bits   an integer.
     * @return  the {@code float} floating-point value with the same bit
     *          pattern.
     */
    public static native float intBitsToFloat(int bits);

    
Compares two Float objects numerically. There are two ways in which comparisons performed by this method differ from those performed by the Java language numerical comparison operators (<, <=, ==, >=, >) when applied to primitive float values: 
  •  Float.NaN is considered by this method to be equal to itself and greater than all other float values (including Float.POSITIVE_INFINITY). 
  •  0.0f is considered by this method to be greater than -0.0f. 

This ensures that the natural ordering of Float objects imposed by this method is consistent with equals.

Params:
  • anotherFloat –  the Float to be compared.
See Also:
Returns: the value 0 if anotherFloat is numerically equal to this Float; a value less than 0 if this Float is numerically less than anotherFloat; and a value greater than 0 if this Float is numerically greater than anotherFloat.
Since:  1.2
/**
     * Compares two {@code Float} objects numerically.  There are
     * two ways in which comparisons performed by this method differ
     * from those performed by the Java language numerical comparison
     * operators ({@code <, <=, ==, >=, >}) when
     * applied to primitive {@code float} values:
     *
     * <ul><li>
     *          {@code Float.NaN} is considered by this method to
     *          be equal to itself and greater than all other
     *          {@code float} values
     *          (including {@code Float.POSITIVE_INFINITY}).
     * <li>
     *          {@code 0.0f} is considered by this method to be greater
     *          than {@code -0.0f}.
     * </ul>
     *
     * This ensures that the <i>natural ordering</i> of {@code Float}
     * objects imposed by this method is <i>consistent with equals</i>.
     *
     * @param   anotherFloat   the {@code Float} to be compared.
     * @return  the value {@code 0} if {@code anotherFloat} is
     *          numerically equal to this {@code Float}; a value
     *          less than {@code 0} if this {@code Float}
     *          is numerically less than {@code anotherFloat};
     *          and a value greater than {@code 0} if this
     *          {@code Float} is numerically greater than
     *          {@code anotherFloat}.
     *
     * @since   1.2
     * @see Comparable#compareTo(Object)
     */
    public int compareTo(Float anotherFloat) {
        return Float.compare(value, anotherFloat.value);
    }

    
Compares the two specified float values. The sign of the integer value returned is the same as that of the integer that would be returned by the call: 
   new Float(f1).compareTo(new Float(f2))



Params:
  • f1 –  the first float to compare.
  • f2 –  the second float to compare.
Returns: the value 0 if f1 is numerically equal to f2; a value less than 0 if f1 is numerically less than f2; and a value greater than 0 if f1 is numerically greater than f2.
Since:1.4
/**
     * Compares the two specified {@code float} values. The sign
     * of the integer value returned is the same as that of the
     * integer that would be returned by the call:
     * <pre>
     *    new Float(f1).compareTo(new Float(f2))
     * </pre>
     *
     * @param   f1        the first {@code float} to compare.
     * @param   f2        the second {@code float} to compare.
     * @return  the value {@code 0} if {@code f1} is
     *          numerically equal to {@code f2}; a value less than
     *          {@code 0} if {@code f1} is numerically less than
     *          {@code f2}; and a value greater than {@code 0}
     *          if {@code f1} is numerically greater than
     *          {@code f2}.
     * @since 1.4
     */
    public static int compare(float f1, float f2) {
       if (f1 < f2)
            return -1;           // Neither val is NaN, thisVal is smaller
        if (f1 > f2)
            return 1;            // Neither val is NaN, thisVal is larger

        int thisBits = Float.floatToIntBits(f1);
        int anotherBits = Float.floatToIntBits(f2);

        return (thisBits == anotherBits ?  0 : // Values are equal
                (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
                 1));                          // (0.0, -0.0) or (NaN, !NaN)
    }

    
use serialVersionUID from JDK 1.0.2 for interoperability 
/** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = -2671257302660747028L;
}