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1420 lines (1347 loc) · 55 KB
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/*
* Copyright (c) 1994, 2026, 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 java.lang.invoke.MethodHandles;
import java.lang.constant.Constable;
import java.lang.constant.ConstantDesc;
import java.util.Optional;
import jdk.internal.math.FloatConsts;
import jdk.internal.math.FloatingDecimal;
import jdk.internal.math.FloatToDecimal;
import jdk.internal.value.Deserializer;
import jdk.internal.vm.annotation.IntrinsicCandidate;
/**
* The {@code Float} class is the {@linkplain
* java.lang##wrapperClass wrapper class} for values of the primitive
* type {@code float}. 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}.
*
* <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
* class; programmers should treat instances that are {@linkplain #equals(Object) equal}
* as interchangeable and should not use instances for synchronization or
* with {@linkplain java.lang.ref.Reference object references}.
*
* <div class="preview-block">
* <div class="preview-comment">
* When preview features are enabled, {@code Float} is a {@linkplain Class#isValue value class}.
* Use of value class instances for synchronization or with
* {@linkplain java.lang.ref.Reference object references} result in
* {@link IdentityException}.
* </div>
* </div>
*
* <h2><a id=equivalenceRelation>Floating-point Equality, Equivalence,
* and Comparison</a></h2>
*
* The class {@code java.lang.Double} has a {@linkplain
* Double##equivalenceRelation discussion of equality,
* equivalence, and comparison of floating-point values} that is
* equally applicable to {@code float} values.
*
* <h2><a id=decimalToBinaryConversion>Decimal ↔ Binary Conversion Issues</a></h2>
*
* The {@linkplain Double##decimalToBinaryConversion discussion of binary to
* decimal conversion issues} in {@code java.lang.Double} is also
* applicable to {@code float} values.
*
* @spec https://standards.ieee.org/ieee/754/6210/
* IEEE Standard for Floating-Point Arithmetic
*
* @since 1.0
*/
@jdk.internal.ValueBased
// See doc/value-class-preview.md for an overview of value class generation
public final /*value*/ class Float extends Number
implements Comparable<Float>, Constable, ConstantDesc {
/**
* 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 {@linkplain Double##equivalenceRelation 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
/**
* The number of bits used to represent a {@code float} value,
* {@value}.
*
* @since 1.5
*/
public static final int SIZE = 32;
/**
* The number of bits in the significand of a {@code float} value,
* {@value}. This is the parameter N in section {@jls 4.2.3} of
* <cite>The Java Language Specification</cite>.
*
* @since 19
*/
public static final int PRECISION = 24;
/**
* Maximum exponent a finite {@code float} variable may have,
* {@value}. It is equal to the value returned by {@code
* Math.getExponent(Float.MAX_VALUE)}.
*
* @since 1.6
*/
public static final int MAX_EXPONENT = (1 << (SIZE - PRECISION - 1)) - 1; // 127
/**
* Minimum exponent a normalized {@code float} variable may have,
* {@value}. It is equal to the value returned by {@code
* Math.getExponent(Float.MIN_NORMAL)}.
*
* @since 1.6
*/
public static final int MIN_EXPONENT = 1 - MAX_EXPONENT; // -126
/**
* The number of bytes used to represent a {@code float} value,
* {@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
*/
public static final Class<Float> TYPE = 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> Otherwise <i>m</i> is positive and finite.
* It is converted to a string in two stages:
* <ul>
* <li> <em>Selection of a decimal</em>:
* A well-defined decimal <i>d</i><sub><i>m</i></sub>
* is selected to represent <i>m</i>.
* This decimal is (almost always) the <em>shortest</em> one that
* rounds to <i>m</i> according to the round to nearest
* rounding policy of IEEE 754 floating-point arithmetic.
* <li> <em>Formatting as a string</em>:
* The decimal <i>d</i><sub><i>m</i></sub> is formatted as a string,
* either in plain or in computerized scientific notation,
* depending on its value.
* </ul>
* </ul>
* </ul>
*
* <p>A <em>decimal</em> is a number of the form
* <i>s</i>×10<sup><i>i</i></sup>
* for some (unique) integers <i>s</i> > 0 and <i>i</i> such that
* <i>s</i> is not a multiple of 10.
* These integers are the <em>significand</em> and
* the <em>exponent</em>, respectively, of the decimal.
* The <em>length</em> of the decimal is the (unique)
* positive integer <i>n</i> meeting
* 10<sup><i>n</i>-1</sup> ≤ <i>s</i> < 10<sup><i>n</i></sup>.
*
* <p>The decimal <i>d</i><sub><i>m</i></sub> for a finite positive <i>m</i>
* is defined as follows:
* <ul>
* <li>Let <i>R</i> be the set of all decimals that round to <i>m</i>
* according to the usual <em>round to nearest</em> rounding policy of
* IEEE 754 floating-point arithmetic.
* <li>Let <i>p</i> be the minimal length over all decimals in <i>R</i>.
* <li>When <i>p</i> ≥ 2, let <i>T</i> be the set of all decimals
* in <i>R</i> with length <i>p</i>.
* Otherwise, let <i>T</i> be the set of all decimals
* in <i>R</i> with length 1 or 2.
* <li>Define <i>d</i><sub><i>m</i></sub> as the decimal in <i>T</i>
* that is closest to <i>m</i>.
* Or if there are two such decimals in <i>T</i>,
* select the one with the even significand.
* </ul>
*
* <p>The (uniquely) selected decimal <i>d</i><sub><i>m</i></sub>
* is then formatted.
* Let <i>s</i>, <i>i</i> and <i>n</i> be the significand, exponent and
* length of <i>d</i><sub><i>m</i></sub>, respectively.
* Further, let <i>e</i> = <i>n</i> + <i>i</i> - 1 and let
* <i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub>
* be the usual decimal expansion of <i>s</i>.
* Note that <i>s</i><sub>1</sub> ≠ 0
* and <i>s</i><sub><i>n</i></sub> ≠ 0.
* Below, the decimal point {@code '.'} is {@code '\u005Cu002E'}
* and the exponent indicator {@code 'E'} is {@code '\u005Cu0045'}.
* <ul>
* <li>Case -3 ≤ <i>e</i> < 0:
* <i>d</i><sub><i>m</i></sub> is formatted as
* <code>0.0</code>…<code>0</code><!--
* --><i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub>,
* where there are exactly -(<i>n</i> + <i>i</i>) zeroes between
* the decimal point and <i>s</i><sub>1</sub>.
* For example, 123 × 10<sup>-4</sup> is formatted as
* {@code 0.0123}.
* <li>Case 0 ≤ <i>e</i> < 7:
* <ul>
* <li>Subcase <i>i</i> ≥ 0:
* <i>d</i><sub><i>m</i></sub> is formatted as
* <i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub><!--
* --><code>0</code>…<code>0.0</code>,
* where there are exactly <i>i</i> zeroes
* between <i>s</i><sub><i>n</i></sub> and the decimal point.
* For example, 123 × 10<sup>2</sup> is formatted as
* {@code 12300.0}.
* <li>Subcase <i>i</i> < 0:
* <i>d</i><sub><i>m</i></sub> is formatted as
* <i>s</i><sub>1</sub>…<!--
* --><i>s</i><sub><i>n</i>+<i>i</i></sub><code>.</code><!--
* --><i>s</i><sub><i>n</i>+<i>i</i>+1</sub>…<!--
* --><i>s</i><sub><i>n</i></sub>,
* where there are exactly -<i>i</i> digits to the right of
* the decimal point.
* For example, 123 × 10<sup>-1</sup> is formatted as
* {@code 12.3}.
* </ul>
* <li>Case <i>e</i> < -3 or <i>e</i> ≥ 7:
* computerized scientific notation is used to format
* <i>d</i><sub><i>m</i></sub>.
* Here <i>e</i> is formatted as by {@link Integer#toString(int)}.
* <ul>
* <li>Subcase <i>n</i> = 1:
* <i>d</i><sub><i>m</i></sub> is formatted as
* <i>s</i><sub>1</sub><code>.0E</code><i>e</i>.
* For example, 1 × 10<sup>23</sup> is formatted as
* {@code 1.0E23}.
* <li>Subcase <i>n</i> > 1:
* <i>d</i><sub><i>m</i></sub> is formatted as
* <i>s</i><sub>1</sub><code>.</code><i>s</i><sub>2</sub><!--
* -->…<i>s</i><sub><i>n</i></sub><code>E</code><i>e</i>.
* For example, 123 × 10<sup>-21</sup> is formatted as
* {@code 1.23E-19}.
* </ul>
* </ul>
*
* <p>To create localized string representations of a floating-point
* value, use subclasses of {@link java.text.NumberFormat}.
*
* @apiNote
* This method corresponds to the general functionality of the
* convertToDecimalCharacter operation defined in IEEE 754;
* however, that operation is defined in terms of specifying the
* number of significand digits used in the conversion.
* Code to do such a conversion in the Java platform includes
* converting the {@code float} to a {@link java.math.BigDecimal
* BigDecimal} exactly and then rounding the {@code BigDecimal} to
* the desired number of digits; sample code:
* {@snippet lang=java :
* floatf = 0.1f;
* int digits = 15;
* BigDecimal bd = new BigDecimal(f);
* String result = bd.round(new MathContext(digits, RoundingMode.HALF_UP));
* // 0.100000001490116
* }
*
* @param f the {@code float} to be converted.
* @return a string representation of the argument.
*/
public static String toString(float f) {
return FloatToDecimal.toString(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>
*
* @apiNote
* This method corresponds to the convertToHexCharacter operation
* defined in IEEE 754.
*
* @param f the {@code float} to be converted.
* @return a hex string representation of the argument.
* @since 1.5
*/
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));
// The char sequence "-1022" can only appear in the
// representation of the exponent, not in the (hex) significand.
return s.replace("-1022", "-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>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.
*
* @apiNote To interpret localized string representations of a
* floating-point value, or string representations that have
* non-ASCII digits, use {@link java.text.NumberFormat}. For
* example,
* {@snippet lang="java" :
* NumberFormat.getInstance(l).parse(s).floatValue();
* }
* where {@code l} is the desired locale, or
* {@link java.util.Locale#ROOT} if locale insensitive.
*
* @apiNote
* This method corresponds to the convertFromDecimalCharacter and
* convertFromHexCharacter operations defined in IEEE 754.
*
* @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.
* @see Double##decimalToBinaryConversion Decimal ↔ Binary Conversion Issues
*/
public static Float valueOf(String s) throws NumberFormatException {
return new Float(parseFloat(s));
}
/**
* Returns a {@code Float} instance representing the specified
* {@code float} value.
* <div class="preview-block">
* <div class="preview-comment">
* <p>
* - When preview features are NOT enabled, {@code Float} is an identity class.
* 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.
* </p>
* <p>
* - When preview features are enabled, {@code Float} is a {@linkplain Class#isValue value class}.
* The {@code valueOf} behavior is the same as invoking the constructor.
* </p>
* </div>
* </div>
*
* @param f a float value.
* @return a {@code Float} instance representing {@code f}.
* @since 1.5
*/
@IntrinsicCandidate
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)
* @see Double##decimalToBinaryConversion Decimal ↔ Binary Conversion Issues
* @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.
*
* @apiNote
* This method corresponds to the isNaN operation defined in IEEE
* 754.
*
* @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.
*
* @apiNote
* This method corresponds to the isInfinite operation defined in
* IEEE 754.
*
* @param v the value to be tested.
* @return {@code true} if the argument is positive infinity or
* negative infinity; {@code false} otherwise.
*/
@IntrinsicCandidate
public static boolean isInfinite(float v) {
return Math.abs(v) > MAX_VALUE;
}
/**
* Returns {@code true} if the argument is a finite floating-point
* value; returns {@code false} otherwise (for NaN and infinity
* arguments).
*
* @apiNote
* This method corresponds to the isFinite operation defined in
* IEEE 754.
*
* @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
*/
@IntrinsicCandidate
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")
@Deserializer("value")
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 Conversion
*/
@Override
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 Conversion
* @since 1.1
*/
@Override
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this {@code Float} as an {@code int} after
* a narrowing primitive conversion.
*
* @apiNote
* This method corresponds to the convertToIntegerTowardZero
* operation defined in IEEE 754.
*
* @return the {@code float} value represented by this object
* converted to type {@code int}
* @jls 5.1.3 Narrowing Primitive Conversion
*/
@Override
public int intValue() {
return (int)value;
}
/**
* Returns value of this {@code Float} as a {@code long} after a
* narrowing primitive conversion.
*
* @apiNote
* This method corresponds to the convertToIntegerTowardZero
* operation defined in IEEE 754.
*
* @return the {@code float} value represented by this object
* converted to type {@code long}
* @jls 5.1.3 Narrowing Primitive Conversion
*/
@Override
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
*/
@Override
@IntrinsicCandidate
public float floatValue() {
return value;
}
/**
* Returns the value of this {@code Float} as a {@code double}
* after a widening primitive conversion.
*
* @apiNote
* This method corresponds to the convertFormat operation defined
* in IEEE 754.
*
* @return the {@code float} value represented by this
* object converted to type {@code double}
* @jls 5.1.2 Widening Primitive Conversion
*/
@Override
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.
* In other words, {@linkplain Double##repEquivalence
* representation equivalence} is used to compare the {@code
* float} values.
*
* @apiNote
* This method is defined in terms of {@link
* #floatToIntBits(float)} rather than the {@code ==} operator on
* {@code float} values since the {@code ==} operator does
* <em>not</em> define an equivalence relation and to satisfy the
* {@linkplain Object#equals equals contract} an equivalence
* relation must be implemented; see {@linkplain Double##equivalenceRelation
* this discussion for details of floating-point equality and equivalence}.
*
* @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)
* @jls 15.21.1 Numerical Equality Operators == and !=
*/
public boolean equals(Object obj) {
return (obj instanceof Float f) &&
(floatToIntBits(f.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.
*/
@IntrinsicCandidate
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
*/
@IntrinsicCandidate
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.