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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.FloatingDecimal;
import jdk.internal.math.DoubleConsts;
import jdk.internal.vm.annotation.IntrinsicCandidate;


The Double class wraps a value of the primitive type double in an object. An object of type Double contains a single field whose type is double. 
In addition, this class provides several methods for converting a double to a String and a String to a double, as well as other constants and methods useful when dealing with a double. 
This is a value-based class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail. 
Floating-point Equality, Equivalence,
and Comparison
 IEEE 754 floating-point values include finite nonzero values, signed zeros (+0.0 and -0.0), signed infinities positive infinity and negative infinity), and NaN (not-a-number). 
An equivalence relation on a set of values is a boolean relation on pairs of values that is reflexive, symmetric, and transitive. For more discussion of equivalence relations and object equality, see the Object.equals specification. An equivalence relation partitions the values it operates over into sets called equivalence classes.  All the
members of the equivalence class are equal to each other under the
relation. An equivalence class may contain only a single member. At
least for some purposes, all the members of an equivalence class
are substitutable for each other.  In particular, in a numeric
expression equivalent values can be substituted for one
another without changing the result of the expression, meaning
changing the equivalence class of the result of the expression.

Notably, the built-in == operation on floating-point values is not an equivalence relation. Despite not defining an equivalence relation, the semantics of the IEEE 754 == operator were deliberately designed to meet other needs of numerical computation. There are two exceptions where the properties of an equivalence relation are not satisfied by 
== on floating-point values: 
    

  • If v1 and v2 are both NaN, then v1
== v2 has the value false. Therefore, for two NaN arguments the reflexive property of an equivalence
relation is not satisfied by the == operator. 
  • If v1 represents +0.0 while v2 represents -0.0, or vice versa, then v1 == v2 has the value true even though +0.0 and -0.0 are distinguishable under various floating-point operations. For example, 1.0/+0.0 evaluates to positive infinity while 1.0/-0.0 evaluates to negative infinity and positive infinity and negative infinity are neither equal to each other nor equivalent to each other. Thus, while a signed zero input most commonly determines the sign of a zero result, because of dividing by zero, +0.0 and -0.0 may not be substituted for each other in general. The sign of a zero input also has a non-substitutable effect on the result of some math library methods. 


For ordered comparisons using the built-in comparison operators (<, <=, etc.), NaN values have another anomalous situation: a NaN is neither less than, nor greater than, nor equal to any value, including itself. This means the trichotomy of
comparison does not hold.

To provide the appropriate semantics for equals and compareTo methods, those methods cannot simply be wrappers around == or ordered comparison operations. Instead, equals defines NaN arguments to be equal to each other and defines +0.0 to not be equal to 
-0.0, restoring reflexivity. For comparisons, compareTo defines a total order where 
-0.0 is less than +0.0 and where a NaN is equal to itself and considered greater than positive infinity. 
The operational semantics of equals and 
compareTo are expressed in terms of 
bit-wise converting the floating-point values to integral values. 
The natural ordering implemented by 
compareTo is consistent with equals. That is, two objects are reported as equal by equals if and only if compareTo on those objects returns zero. 
The adjusted behaviors defined for equals and 
compareTo allow instances of wrapper classes to work properly with conventional data structures. For example, defining NaN values to be equals to one another allows NaN to be used as an element of a HashSet or as the key of a HashMap. Similarly, defining 
compareTo as a total ordering, including +0.0, 
-0.0, and NaN, allows instances of wrapper classes to be used as elements of a SortedSet or as keys of a SortedMap. 
Author: Lee Boynton,  Arthur van Hoff,  Joseph D. Darcy
@jls4.2.3 Floating-Point Types, Formats, and Values
@jls4.2.4. Floating-Point Operations
@jls15.21.1 Numerical Equality Operators == and !=
@jls15.20.1 Numerical Comparison Operators <, <=, >, and >=
Since:1.0
/**
 * The {@code Double} class wraps a value of the primitive type
 * {@code double} in an object. An object of type
 * {@code Double} contains a single field whose type is
 * {@code double}.
 *
 * <p>In addition, this class provides several methods for converting a
 * {@code double} to a {@code String} and a
 * {@code String} to a {@code double}, as well as other
 * constants and methods useful when dealing with a
 * {@code double}.
 *
 * <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 unpredictable behavior may
 * occur. For example, in a future release, synchronization may fail.
 *
 * <h2><a id=equivalenceRelation>Floating-point Equality, Equivalence,
 * and Comparison</a></h2>
 *
 * IEEE 754 floating-point values include finite nonzero values,
 * signed zeros ({@code +0.0} and {@code -0.0}), signed infinities
 * {@linkplain Double#POSITIVE_INFINITY positive infinity} and
 * {@linkplain Double#NEGATIVE_INFINITY negative infinity}), and
 * {@linkplain Double#NaN NaN} (not-a-number).
 *
 * <p>An <em>equivalence relation</em> on a set of values is a boolean
 * relation on pairs of values that is reflexive, symmetric, and
 * transitive. For more discussion of equivalence relations and object
 * equality, see the {@link Object#equals Object.equals}
 * specification. An equivalence relation partitions the values it
 * operates over into sets called <i>equivalence classes</i>.  All the
 * members of the equivalence class are equal to each other under the
 * relation. An equivalence class may contain only a single member. At
 * least for some purposes, all the members of an equivalence class
 * are substitutable for each other.  In particular, in a numeric
 * expression equivalent values can be <em>substituted</em> for one
 * another without changing the result of the expression, meaning
 * changing the equivalence class of the result of the expression.
 *
 * <p>Notably, the built-in {@code ==} operation on floating-point
 * values is <em>not</em> an equivalence relation. Despite not
 * defining an equivalence relation, the semantics of the IEEE 754
 * {@code ==} operator were deliberately designed to meet other needs
 * of numerical computation. There are two exceptions where the
 * properties of an equivalence relation are not satisfied by {@code
 * ==} on floating-point values:
 *
 * <ul>
 *
 * <li>If {@code v1} and {@code v2} are both NaN, then {@code v1
 * == v2} has the value {@code false}. Therefore, for two NaN
 * arguments the <em>reflexive</em> property of an equivalence
 * relation is <em>not</em> satisfied by the {@code ==} operator.
 *
 * <li>If {@code v1} represents {@code +0.0} while {@code v2}
 * represents {@code -0.0}, or vice versa, then {@code v1 == v2} has
 * the value {@code true} even though {@code +0.0} and {@code -0.0}
 * are distinguishable under various floating-point operations. For
 * example, {@code 1.0/+0.0} evaluates to positive infinity while
 * {@code 1.0/-0.0} evaluates to <em>negative</em> infinity and
 * positive infinity and negative infinity are neither equal to each
 * other nor equivalent to each other. Thus, while a signed zero input
 * most commonly determines the sign of a zero result, because of
 * dividing by zero, {@code +0.0} and {@code -0.0} may not be
 * substituted for each other in general. The sign of a zero input
 * also has a non-substitutable effect on the result of some math
 * library methods.
 *
 * </ul>
 *
 * <p>For ordered comparisons using the built-in comparison operators
 * ({@code <}, {@code <=}, etc.), NaN values have another anomalous
 * situation: a NaN is neither less than, nor greater than, nor equal
 * to any value, including itself. This means the <i>trichotomy of
 * comparison</i> does <em>not</em> hold.
 *
 * <p>To provide the appropriate semantics for {@code equals} and
 * {@code compareTo} methods, those methods cannot simply be wrappers
 * around {@code ==} or ordered comparison operations. Instead, {@link
 * Double#equals equals} defines NaN arguments to be equal to each
 * other and defines {@code +0.0} to <em>not</em> be equal to {@code
 * -0.0}, restoring reflexivity. For comparisons, {@link
 * Double#compareTo compareTo} defines a total order where {@code
 * -0.0} is less than {@code +0.0} and where a NaN is equal to itself
 * and considered greater than positive infinity.
 *
 * <p>The operational semantics of {@code equals} and {@code
 * compareTo} are expressed in terms of {@linkplain #doubleToLongBits
 * bit-wise converting} the floating-point values to integral values.
 *
 * <p>The <em>natural ordering</em> implemented by {@link #compareTo
 * compareTo} is {@linkplain Comparable consistent with equals}. That
 * is, two objects are reported as equal by {@code equals} if and only
 * if {@code compareTo} on those objects returns zero.
 *
 * <p>The adjusted behaviors defined for {@code equals} and {@code
 * compareTo} allow instances of wrapper classes to work properly with
 * conventional data structures. For example, defining NaN
 * values to be {@code equals} to one another allows NaN to be used as
 * an element of a {@link java.util.HashSet HashSet} or as the key of
 * a {@link java.util.HashMap HashMap}. Similarly, defining {@code
 * compareTo} as a total ordering, including {@code +0.0}, {@code
 * -0.0}, and NaN, allows instances of wrapper classes to be used as
 * elements of a {@link java.util.SortedSet SortedSet} or as keys of a
 * {@link java.util.SortedMap SortedMap}.
 *
 * @jls 4.2.3 Floating-Point Types, Formats, and Values
 * @jls 4.2.4. Floating-Point Operations
 * @jls 15.21.1 Numerical Equality Operators == and !=
 * @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
 *
 * @author  Lee Boynton
 * @author  Arthur van Hoff
 * @author  Joseph D. Darcy
 * @since 1.0
 */
@jdk.internal.ValueBased
public final class Double extends Number
        implements Comparable<Double>, Constable, ConstantDesc {
    
A constant holding the positive infinity of type double. It is equal to the value returned by Double.longBitsToDouble(0x7ff0000000000000L). 
/**
     * A constant holding the positive infinity of type
     * {@code double}. It is equal to the value returned by
     * {@code Double.longBitsToDouble(0x7ff0000000000000L)}.
     */
    public static final double POSITIVE_INFINITY = 1.0 / 0.0;

    
A constant holding the negative infinity of type double. It is equal to the value returned by Double.longBitsToDouble(0xfff0000000000000L). 
/**
     * A constant holding the negative infinity of type
     * {@code double}. It is equal to the value returned by
     * {@code Double.longBitsToDouble(0xfff0000000000000L)}.
     */
    public static final double NEGATIVE_INFINITY = -1.0 / 0.0;

    
A constant holding a Not-a-Number (NaN) value of type double. It is equivalent to the value returned by Double.longBitsToDouble(0x7ff8000000000000L). 
/**
     * A constant holding a Not-a-Number (NaN) value of type
     * {@code double}. It is equivalent to the value returned by
     * {@code Double.longBitsToDouble(0x7ff8000000000000L)}.
     */
    public static final double NaN = 0.0d / 0.0;

    
A constant holding the largest positive finite value of type double, (2-2-52)·21023. It is equal to the hexadecimal floating-point literal 0x1.fffffffffffffP+1023 and also equal to Double.longBitsToDouble(0x7fefffffffffffffL). 
/**
     * A constant holding the largest positive finite value of type
     * {@code double},
     * (2-2<sup>-52</sup>)&middot;2<sup>1023</sup>.  It is equal to
     * the hexadecimal floating-point literal
     * {@code 0x1.fffffffffffffP+1023} and also equal to
     * {@code Double.longBitsToDouble(0x7fefffffffffffffL)}.
     */
    public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308

    
A constant holding the smallest positive normal value of type double, 2-1022. It is equal to the hexadecimal floating-point literal 0x1.0p-1022 and also equal to Double.longBitsToDouble(0x0010000000000000L). 
Since:1.6
/**
     * A constant holding the smallest positive normal value of type
     * {@code double}, 2<sup>-1022</sup>.  It is equal to the
     * hexadecimal floating-point literal {@code 0x1.0p-1022} and also
     * equal to {@code Double.longBitsToDouble(0x0010000000000000L)}.
     *
     * @since 1.6
     */
    public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308

    
A constant holding the smallest positive nonzero value of type double, 2-1074. It is equal to the hexadecimal floating-point literal 0x0.0000000000001P-1022 and also equal to Double.longBitsToDouble(0x1L). 
/**
     * A constant holding the smallest positive nonzero value of type
     * {@code double}, 2<sup>-1074</sup>. It is equal to the
     * hexadecimal floating-point literal
     * {@code 0x0.0000000000001P-1022} and also equal to
     * {@code Double.longBitsToDouble(0x1L)}.
     */
    public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324

    
Maximum exponent a finite double variable may have. It is equal to the value returned by Math.getExponent(Double.MAX_VALUE). 
Since:1.6
/**
     * Maximum exponent a finite {@code double} variable may have.
     * It is equal to the value returned by
     * {@code Math.getExponent(Double.MAX_VALUE)}.
     *
     * @since 1.6
     */
    public static final int MAX_EXPONENT = 1023;

    
Minimum exponent a normalized double variable may have. It is equal to the value returned by Math.getExponent(Double.MIN_NORMAL). 
Since:1.6
/**
     * Minimum exponent a normalized {@code double} variable may
     * have.  It is equal to the value returned by
     * {@code Math.getExponent(Double.MIN_NORMAL)}.
     *
     * @since 1.6
     */
    public static final int MIN_EXPONENT = -1022;

    
The number of bits used to represent a double value. 
Since:1.5
/**
     * The number of bits used to represent a {@code double} value.
     *
     * @since 1.5
     */
    public static final int SIZE = 64;

    
The number of bytes used to represent a double value. 
Since:1.8
/**
     * The number of bytes used to represent a {@code double} value.
     *
     * @since 1.8
     */
    public static final int BYTES = SIZE / Byte.SIZE;

    
The Class instance representing the primitive type double. 
Since:1.1
/**
     * The {@code Class} instance representing the primitive type
     * {@code double}.
     *
     * @since 1.1
     */
    @SuppressWarnings("unchecked")
    public static final Class<Double>   TYPE = (Class<Double>) Class.getPrimitiveClass("double");

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

  • If the argument is NaN, the result is the string "NaN". 
  • Otherwise, the result is a string that represents the sign and magnitude (absolute value) of the argument. If the sign is negative, the first character of the result is '-' ('\u005Cu002D'); if the sign is positive, no sign character appears in the result. As for the magnitude m:

      

    • If m is infinity, it is represented by the characters "Infinity"; thus, positive infinity produces the result "Infinity" and negative infinity produces the result "-Infinity". 
    • If m is zero, it is represented by the characters "0.0"; thus, negative zero produces the result "-0.0" and positive zero produces the result "0.0". 
    • If m is greater than or equal to 10-3 but less
than 107, then it is represented as the integer part of
m, in decimal form with no leading zeroes, followed by '.' ('\u005Cu002E'), followed by one or more decimal digits representing the fractional part of m.

    • If m is less than 10-3 or greater than or
equal to 107, then it is represented in so-called
"computerized scientific notation." Let n be the unique
integer such that 10n ≤ m < 10n+1; then let a be the
mathematically exact quotient of m and
10n so that 1 ≤ a < 10. The magnitude is then represented as the integer part of a, as a single decimal digit, followed by '.' ('\u005Cu002E'), followed by decimal digits representing the fractional part of a, followed by the letter 'E' ('\u005Cu0045'), followed by a representation of n as a decimal integer, as produced by the method Integer.toString(int). 
    


How many digits must be printed for the fractional part of
m or a? There must be at least one digit to represent the fractional part, and beyond that as many, but only as many, more digits as are needed to uniquely distinguish the argument value from adjacent values of type double. That is, suppose that x is the exact mathematical value represented by the decimal
representation produced by this method for a finite nonzero argument
d. Then d must be the double value nearest to x; or if two double values are equally close to x, then d must be one of them and the least
significant bit of the significand of d must be 0. 
To create localized string representations of a floating-point value, use subclasses of NumberFormat. 
Params:
  • d –  the double to be converted.
Returns:a string representation of the argument.
/**
     * Returns a string representation of the {@code double}
     * 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> &le; <i>m</i> {@literal <}
     * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the
     * mathematically exact quotient of <i>m</i> and
     * 10<sup><i>n</i></sup> so that 1 &le; <i>a</i> {@literal <} 10. The
     * magnitude is then represented as the integer part of <i>a</i>,
     * as a single decimal digit, followed by '{@code .}'
     * ({@code '\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 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 double}. 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>d</i>. Then <i>d</i> must be the {@code double} value nearest
     * to <i>x</i>; or if two {@code double} values are equally close
     * to <i>x</i>, then <i>d</i> must be one of them and the least
     * significant bit of the significand of <i>d</i> must be {@code 0}.
     *
     * <p>To create localized string representations of a floating-point
     * value, use subclasses of {@link java.text.NumberFormat}.
     *
     * @param   d   the {@code double} to be converted.
     * @return a string representation of the argument.
     */
    public static String toString(double d) {
        return FloatingDecimal.toJavaFormatString(d);
    }

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

  • If the argument is NaN, the result is the string "NaN". 
  • Otherwise, the result is a string that represents the sign and magnitude of the argument. If the sign is negative, the first character of the result is '-' ('\u005Cu002D'); if the sign is positive, no sign character appears in the result. As for the magnitude m:

      

    • If m is infinity, it is represented by the string "Infinity"; thus, positive infinity produces the result "Infinity" and negative infinity produces the result "-Infinity". 
    • If m is zero, it is represented by the string "0x0.0p0"; thus, negative zero produces the result "-0x0.0p0" and positive zero produces the result "0x0.0p0". 
    • If m is a double value with a normalized representation, substrings are used to represent the significand and exponent fields. The significand is represented by the characters "0x1." followed by a lowercase hexadecimal representation of the rest of the significand as a fraction. Trailing zeros in the hexadecimal representation are removed unless all the digits are zero, in which case a single zero is used. Next, the exponent is represented by "p" followed by a decimal string of the unbiased exponent as if produced by a call to Integer.toString on the exponent value. 
    • If m is a double value with a subnormal representation, the significand is represented by the characters "0x0." followed by a hexadecimal representation of the rest of the significand as a fraction. Trailing zeros in the hexadecimal representation are removed. Next, the exponent is represented by "p-1022". Note that there must be at least one nonzero digit in a subnormal significand. 
    




Examples


Floating-point ValueHexadecimal String




1.0 0x1.0p0

-1.0        -0x1.0p0

2.0 0x1.0p1

3.0 0x1.8p1

0.5 0x1.0p-1

0.25        0x1.0p-2

Double.MAX_VALUE
    0x1.fffffffffffffp1023

Minimum Normal Value
    0x1.0p-1022

Maximum Subnormal Value
    0x0.fffffffffffffp-1022

Double.MIN_VALUE
    0x0.0000000000001p-1022





Author:Joseph D. Darcy
Params:
  • d –  the double to be converted.
Returns:a hex string representation of the argument.
Since:1.5
/**
     * Returns a hexadecimal string representation of the
     * {@code double} 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 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 double} 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 double} 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-1022"}.  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 style="text-align:right">
     * <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 Double.MAX_VALUE}</th>
     *     <td>{@code 0x1.fffffffffffffp1023}</td>
     * <tr><th scope="row">{@code Minimum Normal Value}</th>
     *     <td>{@code 0x1.0p-1022}</td>
     * <tr><th scope="row">{@code Maximum Subnormal Value}</th>
     *     <td>{@code 0x0.fffffffffffffp-1022}</td>
     * <tr><th scope="row">{@code Double.MIN_VALUE}</th>
     *     <td>{@code 0x0.0000000000001p-1022}</td>
     * </tbody>
     * </table>
     * @param   d   the {@code double} to be converted.
     * @return a hex string representation of the argument.
     * @since 1.5
     * @author Joseph D. Darcy
     */
    public static String toHexString(double d) {
        /*
         * Modeled after the "a" conversion specifier in C99, section
         * 7.19.6.1; however, the output of this method is more
         * tightly specified.
         */
        if (!isFinite(d) )
            // For infinity and NaN, use the decimal output.
            return Double.toString(d);
        else {
            // Initialized to maximum size of output.
            StringBuilder answer = new StringBuilder(24);

            if (Math.copySign(1.0, d) == -1.0)    // value is negative,
                answer.append("-");                  // so append sign info

            answer.append("0x");

            d = Math.abs(d);

            if(d == 0.0) {
                answer.append("0.0p0");
            } else {
                boolean subnormal = (d < Double.MIN_NORMAL);

                // Isolate significand bits and OR in a high-order bit
                // so that the string representation has a known
                // length.
                long signifBits = (Double.doubleToLongBits(d)
                                   & DoubleConsts.SIGNIF_BIT_MASK) |
                    0x1000000000000000L;

                // Subnormal values have a 0 implicit bit; normal
                // values have a 1 implicit bit.
                answer.append(subnormal ? "0." : "1.");

                // Isolate the low-order 13 digits of the hex
                // representation.  If all the digits are zero,
                // replace with a single 0; otherwise, remove all
                // trailing zeros.
                String signif = Long.toHexString(signifBits).substring(3,16);
                answer.append(signif.equals("0000000000000") ? // 13 zeros
                              "0":
                              signif.replaceFirst("0{1,12}$", ""));

                answer.append('p');
                // If the value is subnormal, use the E_min exponent
                // value for double; otherwise, extract and report d's
                // exponent (the representation of a subnormal uses
                // E_min -1).
                answer.append(subnormal ?
                              Double.MIN_EXPONENT:
                              Math.getExponent(d));
            }
            return answer.toString();
        }
    }

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





FloatValue:

Signopt NaN 
Signopt Infinity 
Signopt FloatingPointLiteral

Signopt HexFloatingPointLiteral

SignedInteger





HexFloatingPointLiteral:

 HexSignificand BinaryExponent FloatTypeSuffixopt





HexSignificand:

HexNumeral

HexNumeral . 
0x HexDigitsopt
    . HexDigits

0X HexDigitsopt
    . HexDigits





BinaryExponent:

BinaryExponentIndicator SignedInteger





BinaryExponentIndicator:

p 
P 



where Sign, FloatingPointLiteral,
HexNumeral, HexDigits, SignedInteger and
FloatTypeSuffix are as defined in the lexical structure
sections of
The Java Language Specification, except that underscores are not accepted between digits. If s does not have the form of a FloatValue, then a NumberFormatException is thrown. Otherwise, s is regarded as representing an exact decimal value in the usual "computerized scientific notation" or as an exact hexadecimal value; this exact numerical value is then conceptually converted to an "infinitely precise" binary value that is then rounded to type double 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 s is large enough in magnitude (greater than or equal to (MAX_VALUE + ulp(MAX_VALUE)/2), rounding to double will result in an infinity and if the exact value of s is small enough in magnitude (less than or equal to MIN_VALUE/2), rounding to float will result in a zero. Finally, after rounding a Double object representing this double value is returned. 
 To interpret localized string representations of a floating-point value, use subclasses of NumberFormat. 
Note that trailing format specifiers, specifiers that determine the type of a floating-point literal (1.0f is a float value; 1.0d is a double value), do not influence the results of this method. In other words, the numerical value of the input string is converted directly to the target floating-point type. The two-step sequence of conversions, string to float followed by float to double, is not equivalent to converting a string directly to double. For example, the float literal 0.1f is equal to the double value 0.10000000149011612; the float literal 0.1f represents a different numerical value than the double literal 0.1. (The numerical value 0.1 cannot be exactly represented in a binary floating-point number.) 
To avoid calling this method on an invalid string and having a NumberFormatException be thrown, the regular expression below can be used to screen the input string: 

 final String Digits     = "(\\p{Digit}+)";
 final String HexDigits  = "(\\p{XDigit}+)";
 // an exponent is 'e' or 'E' followed by an optionally
 // signed decimal integer.
 final String Exp        = "[eE][+-]?"+Digits;
 final String fpRegex    =
     ("[\\x00-\\x20]*"+  // Optional leading "whitespace"
      "[+-]?(" + // Optional sign character
      "NaN|" +           // "NaN" string
      "Infinity|" +      // "Infinity" string
      // A decimal floating-point string representing a finite positive
      // number without a leading sign has at most five basic pieces:
      // Digits . Digits ExponentPart FloatTypeSuffix
      //
      // Since this method allows integer-only strings as input
      // in addition to strings of floating-point literals, the
      // two sub-patterns below are simplifications of the grammar
      // productions from section 3.10.2 of
      // The Java Language Specification.
      // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
      "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
      // . Digits ExponentPart_opt FloatTypeSuffix_opt
      "(\\.("+Digits+")("+Exp+")?)|"+
      // Hexadecimal strings
      "((" +
       // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
       "(0[xX]" + HexDigits + "(\\.)?)|" +
       // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
       "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
       ")[pP][+-]?" + Digits + "))" +
      "[fFdD]?))" +
      "[\\x00-\\x20]*");// Optional trailing "whitespace"
 if (Pattern.matches(fpRegex, myString))
     Double.valueOf(myString); // Will not throw NumberFormatException
 else {
     // Perform suitable alternative action
 }



Params:
  • s –   the string to be parsed.
Throws:
Returns: a Double object holding the value represented by the String argument.
/**
     * Returns a {@code Double} object holding the
     * {@code double} 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 double}
     * 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(double) ulp(MAX_VALUE)}/2),
     * rounding to {@code double} 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 Double} object representing
     * this {@code double} 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.  The two-step
     * sequence of conversions, string to {@code float} followed
     * by {@code float} to {@code double}, is <em>not</em>
     * equivalent to converting a string directly to
     * {@code double}. For example, the {@code float}
     * literal {@code 0.1f} is equal to the {@code double}
     * value {@code 0.10000000149011612}; the {@code float}
     * literal {@code 0.1f} represents a different numerical
     * value than the {@code double} literal
     * {@code 0.1}. (The numerical value 0.1 cannot be exactly
     * represented in a binary floating-point number.)
     *
     * <p>To avoid calling this method on an invalid string and having
     * a {@code NumberFormatException} be thrown, the regular
     * expression below can be used to screen the input string:
     *
     * <pre>{@code
     *  final String Digits     = "(\\p{Digit}+)";
     *  final String HexDigits  = "(\\p{XDigit}+)";
     *  // an exponent is 'e' or 'E' followed by an optionally
     *  // signed decimal integer.
     *  final String Exp        = "[eE][+-]?"+Digits;
     *  final String fpRegex    =
     *      ("[\\x00-\\x20]*"+  // Optional leading "whitespace"
     *       "[+-]?(" + // Optional sign character
     *       "NaN|" +           // "NaN" string
     *       "Infinity|" +      // "Infinity" string
     *
     *       // A decimal floating-point string representing a finite positive
     *       // number without a leading sign has at most five basic pieces:
     *       // Digits . Digits ExponentPart FloatTypeSuffix
     *       //
     *       // Since this method allows integer-only strings as input
     *       // in addition to strings of floating-point literals, the
     *       // two sub-patterns below are simplifications of the grammar
     *       // productions from section 3.10.2 of
     *       // The Java Language Specification.
     *
     *       // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
     *       "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
     *
     *       // . Digits ExponentPart_opt FloatTypeSuffix_opt
     *       "(\\.("+Digits+")("+Exp+")?)|"+
     *
     *       // Hexadecimal strings
     *       "((" +
     *        // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
     *        "(0[xX]" + HexDigits + "(\\.)?)|" +
     *
     *        // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
     *        "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
     *
     *        ")[pP][+-]?" + Digits + "))" +
     *       "[fFdD]?))" +
     *       "[\\x00-\\x20]*");// Optional trailing "whitespace"
     *
     *  if (Pattern.matches(fpRegex, myString))
     *      Double.valueOf(myString); // Will not throw NumberFormatException
     *  else {
     *      // Perform suitable alternative action
     *  }
     * }</pre>
     *
     * @param      s   the string to be parsed.
     * @return     a {@code Double} object holding the value
     *             represented by the {@code String} argument.
     * @throws     NumberFormatException  if the string does not contain a
     *             parsable number.
     */
    public static Double valueOf(String s) throws NumberFormatException {
        return new Double(parseDouble(s));
    }

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

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

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

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

    
Returns true if the argument is a finite floating-point value; returns false otherwise (for NaN and infinity arguments). 
Params:
  • d – the double value to be tested
Returns:true if the argument is a finite floating-point value, false otherwise.
Since:1.8
/**
     * Returns {@code true} if the argument is a finite floating-point
     * value; returns {@code false} otherwise (for NaN and infinity
     * arguments).
     *
     * @param d the {@code double} 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(double d) {
        return Math.abs(d) <= Double.MAX_VALUE;
    }

    
The value of the Double.

@serial
/**
     * The value of the Double.
     *
     * @serial
     */
    private final double value;

    
Constructs a newly allocated Double object that represents the primitive double argument. 
Params:
  • value –  the value to be represented by the Double.
Deprecated: It is rarely appropriate to use this constructor. The static factory valueOf(double) is generally a better choice, as it is likely to yield significantly better space and time performance.
/**
     * Constructs a newly allocated {@code Double} object that
     * represents the primitive {@code double} argument.
     *
     * @param   value   the value to be represented by the {@code Double}.
     *
     * @deprecated
     * It is rarely appropriate to use this constructor. The static factory
     * {@link #valueOf(double)} is generally a better choice, as it is
     * likely to yield significantly better space and time performance.
     */
    @Deprecated(since="9", forRemoval = true)
    public Double(double value) {
        this.value = value;
    }

    
Constructs a newly allocated Double object that represents the floating-point value of type double represented by the string. The string is converted to a double value as if by the valueOf method. 
Params:
  • s –  a string to be converted to a Double.
Throws:
Deprecated: It is rarely appropriate to use this constructor. Use parseDouble(String) to convert a string to a double primitive, or use valueOf(String) to convert a string to a Double object.
/**
     * Constructs a newly allocated {@code Double} object that
     * represents the floating-point value of type {@code double}
     * represented by the string. The string is converted to a
     * {@code double} value as if by the {@code valueOf} method.
     *
     * @param  s  a string to be converted to a {@code Double}.
     * @throws    NumberFormatException if the string does not contain a
     *            parsable number.
     *
     * @deprecated
     * It is rarely appropriate to use this constructor.
     * Use {@link #parseDouble(String)} to convert a string to a
     * {@code double} primitive, or use {@link #valueOf(String)}
     * to convert a string to a {@code Double} object.
     */
    @Deprecated(since="9", forRemoval = true)
    public Double(String s) throws NumberFormatException {
        value = parseDouble(s);
    }

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

    
Returns true if this Double value is infinitely large in magnitude, false otherwise. 
Returns: true if the value represented by this object is positive infinity or negative infinity; false otherwise.
/**
     * Returns {@code true} if this {@code Double} 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 Double object. The primitive double value represented by this object is converted to a string exactly as if by the method toString of one argument. 
See Also:
Returns: a String representation of this object.
/**
     * Returns a string representation of this {@code Double} object.
     * The primitive {@code double} value represented by this
     * object is converted to a string exactly as if by the method
     * {@code toString} of one argument.
     *
     * @return  a {@code String} representation of this object.
     * @see java.lang.Double#toString(double)
     */
    public String toString() {
        return toString(value);
    }

    
Returns the value of this Double as a byte after a narrowing primitive conversion. 
Returns: the double value represented by this object converted to type byte
@jls5.1.3 Narrowing Primitive Conversion
Since:1.1
/**
     * Returns the value of this {@code Double} as a {@code byte}
     * after a narrowing primitive conversion.
     *
     * @return  the {@code double} value represented by this object
     *          converted to type {@code byte}
     * @jls 5.1.3 Narrowing Primitive Conversion
     * @since 1.1
     */
    public byte byteValue() {
        return (byte)value;
    }

    
Returns the value of this Double as a short after a narrowing primitive conversion. 
Returns: the double value represented by this object converted to type short
@jls5.1.3 Narrowing Primitive Conversion
Since:1.1
/**
     * Returns the value of this {@code Double} as a {@code short}
     * after a narrowing primitive conversion.
     *
     * @return  the {@code double} value represented by this object
     *          converted to type {@code short}
     * @jls 5.1.3 Narrowing Primitive Conversion
     * @since 1.1
     */
    public short shortValue() {
        return (short)value;
    }

    
Returns the value of this Double as an int after a narrowing primitive conversion. 
@jls5.1.3 Narrowing Primitive Conversion
Returns: the double value represented by this object converted to type int
/**
     * Returns the value of this {@code Double} as an {@code int}
     * after a narrowing primitive conversion.
     * @jls 5.1.3 Narrowing Primitive Conversion
     *
     * @return  the {@code double} value represented by this object
     *          converted to type {@code int}
     */
    public int intValue() {
        return (int)value;
    }

    
Returns the value of this Double as a long after a narrowing primitive conversion. 
Returns: the double value represented by this object converted to type long
@jls5.1.3 Narrowing Primitive Conversion
/**
     * Returns the value of this {@code Double} as a {@code long}
     * after a narrowing primitive conversion.
     *
     * @return  the {@code double} value represented by this object
     *          converted to type {@code long}
     * @jls 5.1.3 Narrowing Primitive Conversion
     */
    public long longValue() {
        return (long)value;
    }

    
Returns the value of this Double as a float after a narrowing primitive conversion. 
Returns: the double value represented by this object converted to type float
@jls5.1.3 Narrowing Primitive Conversion
Since:1.0
/**
     * Returns the value of this {@code Double} as a {@code float}
     * after a narrowing primitive conversion.
     *
     * @return  the {@code double} value represented by this object
     *          converted to type {@code float}
     * @jls 5.1.3 Narrowing Primitive Conversion
     * @since 1.0
     */
    public float floatValue() {
        return (float)value;
    }

    
Returns the double value of this Double object. 
Returns:the double value represented by this object
/**
     * Returns the {@code double} value of this {@code Double} object.
     *
     * @return the {@code double} value represented by this object
     */
    @IntrinsicCandidate
    public double doubleValue() {
        return value;
    }

    
Returns a hash code for this Double object. The result is the exclusive OR of the two halves of the long integer bit representation, exactly as produced by the method doubleToLongBits(double), of the primitive double value represented by this Double object. That is, the hash code is the value of the expression: 
 (int)(v^(v>>>32)) 
 where v is defined by: 
 long v = Double.doubleToLongBits(this.doubleValue()); 


Returns: a hash code value for this object.
/**
     * Returns a hash code for this {@code Double} object. The
     * result is the exclusive OR of the two halves of the
     * {@code long} integer bit representation, exactly as
     * produced by the method {@link #doubleToLongBits(double)}, of
     * the primitive {@code double} value represented by this
     * {@code Double} object. That is, the hash code is the value
     * of the expression:
     *
     * <blockquote>
     *  {@code (int)(v^(v>>>32))}
     * </blockquote>
     *
     * where {@code v} is defined by:
     *
     * <blockquote>
     *  {@code long v = Double.doubleToLongBits(this.doubleValue());}
     * </blockquote>
     *
     * @return  a {@code hash code} value for this object.
     */
    @Override
    public int hashCode() {
        return Double.hashCode(value);
    }

    
Returns a hash code for a double value; compatible with Double.hashCode(). 
Params:
  • value – the value to hash
Returns:a hash code value for a double value.
Since:1.8
/**
     * Returns a hash code for a {@code double} value; compatible with
     * {@code Double.hashCode()}.
     *
     * @param value the value to hash
     * @return a hash code value for a {@code double} value.
     * @since 1.8
     */
    public static int hashCode(double value) {
        long bits = doubleToLongBits(value);
        return (int)(bits ^ (bits >>> 32));
    }

    
Compares this object against the specified object. The result is true if and only if the argument is not null and is a Double object that represents a double that has the same value as the double represented by this object. For this purpose, two double values are considered to be the same if and only if the method doubleToLongBits(double) returns the identical long value when applied to each. 
See Also:
API Note: This method is defined in terms of doubleToLongBits(double) rather than the == operator on double values since the == operator does not define an equivalence relation and to satisfy the equals contract an equivalence relation must be implemented; see this discussion for details of
floating-point equality and equivalence.
@jls15.21.1 Numerical Equality Operators == and !=
/**
     * 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 Double} object that
     * represents a {@code double} that has the same value as the
     * {@code double} represented by this object. For this
     * purpose, two {@code double} values are considered to be
     * the same if and only if the method {@link
     * #doubleToLongBits(double)} returns the identical
     * {@code long} value when applied to each.
     *
     * @apiNote
     * This method is defined in terms of {@link
     * #doubleToLongBits(double)} rather than the {@code ==} operator
     * on {@code double} 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 <a
     * href="#equivalenceRelation">this discussion</a> for details of
     * floating-point equality and equivalence.
     *
     * @see java.lang.Double#doubleToLongBits(double)
     * @jls 15.21.1 Numerical Equality Operators == and !=
     */
    public boolean equals(Object obj) {
        return (obj instanceof Double)
               && (doubleToLongBits(((Double)obj).value) ==
                      doubleToLongBits(value));
    }

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

Bit 63 (the bit that is selected by the mask 0x8000000000000000L) represents the sign of the floating-point number. Bits 62-52 (the bits that are selected by the mask 0x7ff0000000000000L) represent the exponent. Bits 51-0 (the bits that are selected by the mask 0x000fffffffffffffL) represent the significand (sometimes called the mantissa) of the floating-point number. 
If the argument is positive infinity, the result is 0x7ff0000000000000L. 
If the argument is negative infinity, the result is 0xfff0000000000000L. 
If the argument is NaN, the result is 0x7ff8000000000000L. 
In all cases, the result is a long integer that, when given to the longBitsToDouble(long) method, will produce a floating-point value the same as the argument to doubleToLongBits (except all NaN values are collapsed to a single "canonical" NaN value). 
Params:
  • value –  a double precision floating-point number.
Returns:the bits that represent the floating-point number.
/**
     * Returns a representation of the specified floating-point value
     * according to the IEEE 754 floating-point "double
     * format" bit layout.
     *
     * <p>Bit 63 (the bit that is selected by the mask
     * {@code 0x8000000000000000L}) represents the sign of the
     * floating-point number. Bits
     * 62-52 (the bits that are selected by the mask
     * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
     * (the bits that are selected by the mask
     * {@code 0x000fffffffffffffL}) represent the significand
     * (sometimes called the mantissa) of the floating-point number.
     *
     * <p>If the argument is positive infinity, the result is
     * {@code 0x7ff0000000000000L}.
     *
     * <p>If the argument is negative infinity, the result is
     * {@code 0xfff0000000000000L}.
     *
     * <p>If the argument is NaN, the result is
     * {@code 0x7ff8000000000000L}.
     *
     * <p>In all cases, the result is a {@code long} integer that, when
     * given to the {@link #longBitsToDouble(long)} method, will produce a
     * floating-point value the same as the argument to
     * {@code doubleToLongBits} (except all NaN values are
     * collapsed to a single "canonical" NaN value).
     *
     * @param   value   a {@code double} precision floating-point number.
     * @return the bits that represent the floating-point number.
     */
    @IntrinsicCandidate
    public static long doubleToLongBits(double value) {
        if (!isNaN(value)) {
            return doubleToRawLongBits(value);
        }
        return 0x7ff8000000000000L;
    }

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

Bit 63 (the bit that is selected by the mask 0x8000000000000000L) represents the sign of the floating-point number. Bits 62-52 (the bits that are selected by the mask 0x7ff0000000000000L) represent the exponent. Bits 51-0 (the bits that are selected by the mask 0x000fffffffffffffL) represent the significand (sometimes called the mantissa) of the floating-point number. 
If the argument is positive infinity, the result is 0x7ff0000000000000L. 
If the argument is negative infinity, the result is 0xfff0000000000000L. 
If the argument is NaN, the result is the long integer representing the actual NaN value. Unlike the doubleToLongBits method, doubleToRawLongBits does not collapse all the bit patterns encoding a NaN to a single "canonical" NaN value. 
In all cases, the result is a long integer that, when given to the longBitsToDouble(long) method, will produce a floating-point value the same as the argument to doubleToRawLongBits. 
Params:
  • value –  a double precision floating-point number.
Returns:the bits that represent the floating-point number.
Since:1.3
/**
     * Returns a representation of the specified floating-point value
     * according to the IEEE 754 floating-point "double
     * format" bit layout, preserving Not-a-Number (NaN) values.
     *
     * <p>Bit 63 (the bit that is selected by the mask
     * {@code 0x8000000000000000L}) represents the sign of the
     * floating-point number. Bits
     * 62-52 (the bits that are selected by the mask
     * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
     * (the bits that are selected by the mask
     * {@code 0x000fffffffffffffL}) represent the significand
     * (sometimes called the mantissa) of the floating-point number.
     *
     * <p>If the argument is positive infinity, the result is
     * {@code 0x7ff0000000000000L}.
     *
     * <p>If the argument is negative infinity, the result is
     * {@code 0xfff0000000000000L}.
     *
     * <p>If the argument is NaN, the result is the {@code long}
     * integer representing the actual NaN value.  Unlike the
     * {@code doubleToLongBits} method,
     * {@code doubleToRawLongBits} does not collapse all the bit
     * patterns encoding a NaN to a single "canonical" NaN
     * value.
     *
     * <p>In all cases, the result is a {@code long} integer that,
     * when given to the {@link #longBitsToDouble(long)} method, will
     * produce a floating-point value the same as the argument to
     * {@code doubleToRawLongBits}.
     *
     * @param   value   a {@code double} precision floating-point number.
     * @return the bits that represent the floating-point number.
     * @since 1.3
     */
    @IntrinsicCandidate
    public static native long doubleToRawLongBits(double value);

    
Returns the double 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 "double format" bit layout. 
If the argument is 0x7ff0000000000000L, the result is positive infinity. 
If the argument is 0xfff0000000000000L, the result is negative infinity. 
If the argument is any value in the range 0x7ff0000000000001L through 0x7fffffffffffffffL or in the range 0xfff0000000000001L through 0xffffffffffffffffL, 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 Double.doubleToRawLongBits method. 
In all other cases, let s, e, and m be three
values that can be computed from the argument:


int s = ((bits >> 63) == 0) ? 1 : -1;
int e = (int)((bits >> 52) & 0x7ffL);
long m = (e == 0) ?
                (bits & 0xfffffffffffffL) << 1 :
                (bits & 0xfffffffffffffL) | 0x10000000000000L;


Then the floating-point result equals the value of the mathematical
expression s·m·2e-1075.

Note that this method may not be able to return a double NaN with exactly same bit pattern as the long argument. IEEE 754 distinguishes between two kinds of NaNs, quiet NaNs and signaling NaNs. The differences between the two kinds of NaN are generally not visible in Java. Arithmetic operations on signaling NaNs turn them into quiet NaNs with a different, but often similar, bit pattern. However, on some processors merely copying a signaling NaN also performs that conversion. In particular, copying a signaling NaN to return it to the calling method may perform this conversion. So longBitsToDouble may not be able to return a double with a signaling NaN bit pattern. Consequently, for some long values, doubleToRawLongBits(longBitsToDouble(start)) may not equal start. Moreover, which particular bit patterns represent signaling NaNs is platform dependent; although all NaN bit patterns, quiet or signaling, must be in the NaN range identified above. 
Params:
  • bits –  any long integer.
Returns: the double floating-point value with the same bit pattern.
/**
     * Returns the {@code double} 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
     * "double format" bit layout.
     *
     * <p>If the argument is {@code 0x7ff0000000000000L}, the result
     * is positive infinity.
     *
     * <p>If the argument is {@code 0xfff0000000000000L}, the result
     * is negative infinity.
     *
     * <p>If the argument is any value in the range
     * {@code 0x7ff0000000000001L} through
     * {@code 0x7fffffffffffffffL} or in the range
     * {@code 0xfff0000000000001L} through
     * {@code 0xffffffffffffffffL}, 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 Double.doubleToRawLongBits} 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 >> 63) == 0) ? 1 : -1;
     * int e = (int)((bits >> 52) & 0x7ffL);
     * long m = (e == 0) ?
     *                 (bits & 0xfffffffffffffL) << 1 :
     *                 (bits & 0xfffffffffffffL) | 0x10000000000000L;
     * }</pre></blockquote>
     *
     * Then the floating-point result equals the value of the mathematical
     * expression <i>s</i>&middot;<i>m</i>&middot;2<sup><i>e</i>-1075</sup>.
     *
     * <p>Note that this method may not be able to return a
     * {@code double} NaN with exactly same bit pattern as the
     * {@code long} 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 longBitsToDouble}
     * may not be able to return a {@code double} with a
     * signaling NaN bit pattern.  Consequently, for some
     * {@code long} values,
     * {@code doubleToRawLongBits(longBitsToDouble(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   any {@code long} integer.
     * @return  the {@code double} floating-point value with the same
     *          bit pattern.
     */
    @IntrinsicCandidate
    public static native double longBitsToDouble(long bits);

    
Compares two Double objects numerically. This method imposes a total order on Double objects with two differences compared to the incomplete order defined by the Java language numerical comparison operators (<, <=,
==, >=, >) on double values. 
  •  A NaN is unordered with respect to other values and unequal to itself under the comparison operators. This method chooses to define 
         Double.NaN to be equal to itself and greater than all other double values (including 
         Double.POSITIVE_INFINITY). 
  •  Positive zero and negative zero compare equal numerically, but are distinct and distinguishable values. This method chooses to define positive zero (+0.0d), to be greater than negative zero (-0.0d). 

This ensures that the natural ordering of Double objects imposed by this method is consistent with
equals; see this
discussion for details of floating-point comparison and
ordering.

Params:
  • anotherDouble –  the Double to be compared.
Returns: the value 0 if anotherDouble is numerically equal to this Double; a value less than 0 if this Double is numerically less than anotherDouble; and a value greater than 0 if this Double is numerically greater than anotherDouble.
@jls15.20.1 Numerical Comparison Operators <, <=, >, and >=
Since:  1.2
/**
     * Compares two {@code Double} objects numerically.
     *
     * This method imposes a total order on {@code Double} objects
     * with two differences compared to the incomplete order defined by
     * the Java language numerical comparison operators ({@code <, <=,
     * ==, >=, >}) on {@code double} values.
     *
     * <ul><li> A NaN is <em>unordered</em> with respect to other
     *          values and unequal to itself under the comparison
     *          operators.  This method chooses to define {@code
     *          Double.NaN} to be equal to itself and greater than all
     *          other {@code double} values (including {@code
     *          Double.POSITIVE_INFINITY}).
     *
     *      <li> Positive zero and negative zero compare equal
     *      numerically, but are distinct and distinguishable values.
     *      This method chooses to define positive zero ({@code +0.0d}),
     *      to be greater than negative zero ({@code -0.0d}).
     * </ul>

     * This ensures that the <i>natural ordering</i> of {@code Double}
     * objects imposed by this method is <i>consistent with
     * equals</i>; see <a href="#equivalenceRelation">this
     * discussion</a> for details of floating-point comparison and
     * ordering.
     *
     * @param   anotherDouble   the {@code Double} to be compared.
     * @return  the value {@code 0} if {@code anotherDouble} is
     *          numerically equal to this {@code Double}; a value
     *          less than {@code 0} if this {@code Double}
     *          is numerically less than {@code anotherDouble};
     *          and a value greater than {@code 0} if this
     *          {@code Double} is numerically greater than
     *          {@code anotherDouble}.
     *
     * @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
     * @since   1.2
     */
    public int compareTo(Double anotherDouble) {
        return Double.compare(value, anotherDouble.value);
    }

    
Compares the two specified double values. The sign of the integer value returned is the same as that of the integer that would be returned by the call: 
   new Double(d1).compareTo(new Double(d2))



Params:
  • d1 –  the first double to compare
  • d2 –  the second double to compare
Returns: the value 0 if d1 is numerically equal to d2; a value less than 0 if d1 is numerically less than d2; and a value greater than 0 if d1 is numerically greater than d2.
Since:1.4
/**
     * Compares the two specified {@code double} 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 Double(d1).compareTo(new Double(d2))
     * </pre>
     *
     * @param   d1        the first {@code double} to compare
     * @param   d2        the second {@code double} to compare
     * @return  the value {@code 0} if {@code d1} is
     *          numerically equal to {@code d2}; a value less than
     *          {@code 0} if {@code d1} is numerically less than
     *          {@code d2}; and a value greater than {@code 0}
     *          if {@code d1} is numerically greater than
     *          {@code d2}.
     * @since 1.4
     */
    public static int compare(double d1, double d2) {
        if (d1 < d2)
            return -1;           // Neither val is NaN, thisVal is smaller
        if (d1 > d2)
            return 1;            // Neither val is NaN, thisVal is larger

        // Cannot use doubleToRawLongBits because of possibility of NaNs.
        long thisBits    = Double.doubleToLongBits(d1);
        long anotherBits = Double.doubleToLongBits(d2);

        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 double values together as per the + operator. 
Params:
  • a – the first operand
  • b – the second operand
See Also:
Returns:the sum of a and b
@jls4.2.4 Floating-Point Operations
Since:1.8
/**
     * Adds two {@code double} 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 double sum(double a, double b) {
        return a + b;
    }

    
Returns the greater of two double values as if by calling Math.max. 
Params:
  • a – the first operand
  • b – the second operand
See Also:
Returns:the greater of a and b
Since:1.8
/**
     * Returns the greater of two {@code double} values
     * as if by calling {@link Math#max(double, double) 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 double max(double a, double b) {
        return Math.max(a, b);
    }

    
Returns the smaller of two double values as if by calling Math.min. 
Params:
  • a – the first operand
  • b – the second operand
See Also:
Returns:the smaller of a and b.
Since:1.8
/**
     * Returns the smaller of two {@code double} values
     * as if by calling {@link Math#min(double, double) 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 double min(double a, double b) {
        return Math.min(a, b);
    }

    
Returns an Optional containing the nominal descriptor for this instance, which is the instance itself. 
Returns:an Optional describing the Double instance
Since:12
/**
     * Returns an {@link Optional} containing the nominal descriptor for this
     * instance, which is the instance itself.
     *
     * @return an {@link Optional} describing the {@linkplain Double} instance
     * @since 12
     */
    @Override
    public Optional<Double> describeConstable() {
        return Optional.of(this);
    }

    
Resolves this instance as a ConstantDesc, the result of which is the instance itself. 
Params:
  • lookup – ignored
Returns:the Double instance
Since:12
/**
     * Resolves this instance as a {@link ConstantDesc}, the result of which is
     * the instance itself.
     *
     * @param lookup ignored
     * @return the {@linkplain Double} instance
     * @since 12
     */
    @Override
    public Double resolveConstantDesc(MethodHandles.Lookup lookup) {
        return this;
    }

    
use serialVersionUID from JDK 1.0.2 for interoperability 
/** use serialVersionUID from JDK 1.0.2 for interoperability */
    @java.io.Serial
    private static final long serialVersionUID = -9172774392245257468L;
}