`/*`

* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.

* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

*

* This code is free software; you can redistribute it and/or modify it

* under the terms of the GNU General Public License version 2 only, as

* 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,

* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

*

* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

* or visit www.oracle.com if you need additional information or have any

* questions.

*/

package java.lang;

import sun.misc.FloatingDecimal;

import sun.misc.FloatConsts;

import sun.misc.DoubleConsts;

/**

* 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

* {@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

* {@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

* {@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

* {@code float}, (2-2<sup>-23</sup>)·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

* {@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

* {@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 {@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 {@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 {@code float} value.

*

* @since 1.5

*/

public static final int SIZE = 32;

/**

* The number of bytes used to represent a {@code float} value.

*

* @since 1.8

*/

public static final int BYTES = SIZE / Byte.SIZE;

/**

* The {@code Class} instance representing the primitive type

* {@code float}.

*

* @since JDK1.1

*/

@SuppressWarnings("unchecked")

public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");

/**

* 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 '\u005Cu002D'}); 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 '\u005Cu002E'}), 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>≤

*

<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 ≤ <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 '\u005Cu002E'}), followed by

*

decimal digits representing the fractional part of

*

<i>a</i>, followed by the letter '{@code E}'

*

({@code '\u005Cu0045'}), 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

.

*

* @param

fthe float to be converted.

* @return a string representation of the argument.

*/

public static String toString(float f) {

return FloatingDecimal.toJavaFormatString(f);

}

/**

* 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 '\u005Cu002D'}); 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>Examples</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

fthe {@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(Math.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 {@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>

*

* <dl>

* <dt><i>HexFloatingPointLiteral</i>:

* <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>

* </dl>

*

* <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>

*

* <dl>

* <dt><i>BinaryExponent:</i>

* <dd><i>BinaryExponentIndicator SignedInteger</i>

* </dl>

*

* <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

* <cite>The Java™ Language Specification</cite>,

* except that underscores are not accepted between digits.

* 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.

*

* Note that the round-to-nearest rule also implies overflow and

* underflow behaviour; if the exact value of {@code s} is large

* enough in magnitude (greater than or equal to ({@link

* #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),

* rounding to {@code float} will result in an infinity and if the

* exact value of {@code s} is small enough in magnitude (less

* than or equal to

/2), rounding to float will

* result in a zero.

*

* Finally, after rounding 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

sthe string to be parsed.

* @return

a {@code Float} object holding the value

*

represented by the {@code String} argument.

* @throws

NumberFormatExceptionif the string does not contain a

*

parsable number.

*/

public static Float valueOf(String s) throws NumberFormatException {

return new Float(parseFloat(s));

}

/**

* 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 {@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 NullPointerException

if the string is null

* @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.parseFloat(s);

}

/**

* Returns {@code true} if the specified number is a

* Not-a-Number (NaN) value, {@code false} otherwise.

*

* @param

vthe value to be tested.

* @return

{@code true} if the argument is NaN;

*

{@code false} otherwise.

*/

public static boolean isNaN(float v) {

return (v != v);

}

/**

* Returns {@code true} if the specified number is infinitely

* large in magnitude, {@code false} otherwise.

*

* @param

vthe value to be tested.

* @return

{@code true} if the argument is positive infinity or

*

negative infinity; {@code false} otherwise.

*/

public static boolean isInfinite(float v) {

return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);

}

/**

* Returns {@code true} if the argument is a finite floating-point

* value; returns {@code false} otherwise (for NaN and infinity

* arguments).

*

* @param f the {@code float} value to be tested

* @return {@code true} if the argument is a finite

* floating-point value, {@code false} otherwise.

* @since 1.8

*/

public static boolean isFinite(float f) {

return Math.abs(f) <= FloatConsts.MAX_VALUE;

}

/**

* The value of the Float.

*

* @serial

*/

private final float value;

/**

* Constructs a newly allocated {@code Float} object that

* represents the primitive {@code float} argument.

*

* @param

valuethe value to be represented by the {@code Float}.

*/

public Float(float value) {

this.value = value;

}

/**

* Constructs a newly allocated {@code Float} object that

* represents the argument converted to type {@code float}.

*

* @param

valuethe value to be represented by the {@code Float}.

*/

public Float(double value) {

this.value = (float)value;

}

/**

* 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

NumberFormatExceptionif the string does not contain a

*

parsable number.

* @see

java.lang.Float#valueOf(java.lang.String)

*/

public Float(String s) throws NumberFormatException {

value = parseFloat(s);

}

/**

* 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 {@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 {@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 Float.toString(value);

}

/**

* Returns the value of this {@code Float} as a {@code byte} after

* a narrowing primitive conversion.

*

* @return

the {@code float} value represented by this object

*

converted to type {@code byte}

* @jls 5.1.3 Narrowing Primitive Conversions

*/

public byte byteValue() {

return (byte)value;

}

/**

* Returns the value of this {@code Float} as a {@code short}

* after a narrowing primitive conversion.

*

* @return

the {@code float} value represented by this object

*

converted to type {@code short}

* @jls 5.1.3 Narrowing Primitive Conversions

* @since JDK1.1

*/

public short shortValue() {

return (short)value;

}

/**

* Returns the value of this {@code Float} as an {@code int} after

* a narrowing primitive conversion.

*

* @return

the {@code float} value represented by this object

*

converted to type {@code int}

* @jls 5.1.3 Narrowing Primitive Conversions

*/

public int intValue() {

return (int)value;

}

/**

* Returns value of this {@code Float} as a {@code long} after a

* narrowing primitive conversion.

*

* @return

the {@code float} value represented by this object

*

converted to type {@code long}

* @jls 5.1.3 Narrowing Primitive Conversions

*/

public long longValue() {

return (long)value;

}

/**

* 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 value of this {@code Float} as a {@code double}

* after a widening primitive conversion.

*

* @return the {@code float} value represented by this

*

object converted to type {@code double}

* @jls 5.1.2 Widening Primitive Conversions

*/

public double doubleValue() {

return (double)value;

}

/**

* 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.

*/

@Override

public int hashCode() {

return Float.hashCode(value);

}

/**

* Returns a hash code for a {@code float} value; compatible with

* {@code Float.hashCode()}.

*

* @param value the value to hash

* @return a hash code value for a {@code float} value.

* @since 1.8

*/

public static int hashCode(float value) {

return floatToIntBits(value);

}

/**

* 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.

*

* <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

valuea 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.

*

* <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

valuea floating-point number.

* @return the bits that represent the floating-point number.

* @since 1.3

*/

public static native int floatToRawIntBits(float value);

/**

* 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>{@code

* int s = ((bits >> 31) == 0) ? 1 : -1;

* int e = ((bits >> 23) & 0xff);

* int m = (e == 0) ?

*

(bits & 0x7fffff) << 1 :

*

(bits & 0x7fffff) | 0x800000;

* }</pre></blockquote>

*

* Then the floating-point result equals the value of the mathematical

* expression <i>s</i>·<i>m</i>·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

bitsan integer.

* @return

the {@code float} floating-point value with the same bit

*

pattern.

*/

public static native float intBitsToFloat(int bits);

/**

* 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

anotherFloatthe {@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 {@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

// Cannot use floatToRawIntBits because of possibility of NaNs.

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)

}

/**

* Adds two {@code float} values together as per the + operator.

*

* @param a the first operand

* @param b the second operand

* @return the sum of {@code a} and {@code b}

* @jls 4.2.4 Floating-Point Operations

*

* @since 1.8

*/

public static float sum(float a, float b) {

return a + b;

}

/**

* Returns the greater of two {@code float} values

* as if by calling {@link Math#max(float, float) Math.max}.

*

* @param a the first operand

* @param b the second operand

* @return the greater of {@code a} and {@code b}

*

* @since 1.8

*/

public static float max(float a, float b) {

return Math.max(a, b);

}

/**

* Returns the smaller of two {@code float} values

* as if by calling {@link Math#min(float, float) Math.min}.

*

* @param a the first operand

* @param b the second operand

* @return the smaller of {@code a} and {@code b}

*

* @since 1.8

*/

public static float min(float a, float b) {

return Math.min(a, b);

}

/** use serialVersionUID from JDK 1.0.2 for interoperability */

private static final long serialVersionUID = -2671257302660747028L;

}