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⏎ java/lang/Float.java
/*
* Copyright (c) 1994, 2017, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.lang;
import jdk.internal.math.FloatingDecimal;
import jdk.internal.HotSpotIntrinsicCandidate;
/**
* 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 1.0
*/
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 1.1
*/
@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 {@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 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 class="striped">
* <caption>Examples</caption>
* <thead>
* <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th>
* </thead>
* <tbody>
* <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td>
* <tr><th scope="row">{@code -1.0}</th> <td>{@code -0x1.0p0}</td>
* <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td>
* <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td>
* <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td>
* <tr><th scope="row">{@code 0.25}</th> <td>{@code 0x1.0p-2}</td>
* <tr><th scope="row">{@code Float.MAX_VALUE}</th>
* <td>{@code 0x1.fffffep127}</td>
* <tr><th scope="row">{@code Minimum Normal Value}</th>
* <td>{@code 0x1.0p-126}</td>
* <tr><th scope="row">{@code Maximum Subnormal Value}</th>
* <td>{@code 0x0.fffffep-126}</td>
* <tr><th scope="row">{@code Float.MIN_VALUE}</th>
* <td>{@code 0x0.000002p-126}</td>
* </tbody>
* </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) < Float.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 */
Double.MIN_EXPONENT-
Float.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 {@link #MIN_VALUE}/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 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(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
*/
@HotSpotIntrinsicCandidate
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 v the 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 v the 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) <= Float.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 value the value to be represented by the {@code Float}.
*
* @deprecated
* It is rarely appropriate to use this constructor. The static factory
* {@link #valueOf(float)} is generally a better choice, as it is
* likely to yield significantly better space and time performance.
*/
@Deprecated(since="9")
public Float(float value) {
this.value = value;
}
/**
* 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}.
*
* @deprecated
* It is rarely appropriate to use this constructor. Instead, use the
* static factory method {@link #valueOf(float)} method as follows:
* {@code Float.valueOf((float)value)}.
*/
@Deprecated(since="9")
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 NumberFormatException if the string does not contain a
* parsable number.
*
* @deprecated
* It is rarely appropriate to use this constructor.
* Use {@link #parseFloat(String)} to convert a string to a
* {@code float} primitive, or use {@link #valueOf(String)}
* to convert a string to a {@code Float} object.
*/
@Deprecated(since="9")
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 1.1
*/
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
*/
@HotSpotIntrinsicCandidate
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 value a floating-point number.
* @return the bits that represent the floating-point number.
*/
@HotSpotIntrinsicCandidate
public static int floatToIntBits(float value) {
if (!isNaN(value)) {
return floatToRawIntBits(value);
}
return 0x7fc00000;
}
/**
* 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
*/
@HotSpotIntrinsicCandidate
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 bits an integer.
* @return the {@code float} floating-point value with the same bit
* pattern.
*/
@HotSpotIntrinsicCandidate
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 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 {@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
* @see java.util.function.BinaryOperator
* @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}
* @see java.util.function.BinaryOperator
* @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}
* @see java.util.function.BinaryOperator
* @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;
}
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