`/*`

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

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

*

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

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

* published by the Free Software Foundation.

Oracle designates this

* particular file as subject to the "Classpath" exception as provided

* by Oracle in the LICENSE file that accompanied this code.

*

* This code is distributed in the hope that it will be useful, but WITHOUT

* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

* FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License

* version 2 for more details (a copy is included in the LICENSE file that

* accompanied this code).

*

* You should have received a copy of the GNU General Public License version

* 2 along with this work; if not, write to the Free Software Foundation,

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

*

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

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

* questions.

*/

package java.lang;

import sun.misc.FloatingDecimal;

import sun.misc.FpUtils;

import sun.misc.DoubleConsts;

/**

* 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}.

*

* @author

Lee Boynton

* @author

Arthur van Hoff

* @author

Joseph D. Darcy

* @since JDK1.0

*/

public final class Double extends Number implements Comparable<Double> {

/**

* 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

* {@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

* {@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

* {@code double},

* (2-2<sup>-52</sup>)·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

* {@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

* {@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 {@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 {@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 {@code double} value.

*

* @since 1.5

*/

public static final int SIZE = 64;

/**

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

*

* @since 1.8

*/

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

/**

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

* {@code double}.

*

* @since JDK1.1

*/

@SuppressWarnings("unchecked")

public static final Class<Double>

TYPE = (Class<Double>) Class.getPrimitiveClass("double");

/**

* 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> ≤ <i>m</i> {@literal <}

* 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the

* mathematically exact quotient of <i>m</i> and

* 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The

* magnitude is then represented as the integer part of <i>a</i>,

* as a single decimal digit, followed by '{@code .}'

* ({@code '\u005Cu002E'}), followed by decimal digits

* representing the fractional part of <i>a</i>, followed by the

* letter '{@code E}' ({@code '\u005Cu0045'}), followed

* by a representation of <i>n</i> as a decimal integer, as

* produced by the method {@link 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

.

*

* @param

dthe {@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

* {@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 border>

* <caption>Examples</caption>

* <tr><th>Floating-point Value</th><th>Hexadecimal String</th>

* <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>

* <tr><td>{@code -1.0}</td>

<td>{@code -0x1.0p0}</td>

* <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>

* <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>

* <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>

* <tr><td>{@code 0.25}</td>

<td>{@code 0x1.0p-2}</td>

* <tr><td>{@code Double.MAX_VALUE}</td>

*<td>{@code 0x1.fffffffffffffp1023}</td>

* <tr><td>{@code Minimum Normal Value}</td>

*<td>{@code 0x1.0p-1022}</td>

* <tr><td>{@code Maximum Subnormal Value}</td>

*<td>{@code 0x0.fffffffffffffp-1022}</td>

* <tr><td>{@code Double.MIN_VALUE}</td>

*<td>{@code 0x0.0000000000001p-1022}</td>

* </table>

* @param

dthe {@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 < DoubleConsts.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 ?

DoubleConsts.MIN_EXPONENT:

Math.getExponent(d));

}

return answer.toString();

}

}

/**

* 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

/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.

* @returna {@code Double} object holding the value

*

represented by the {@code String} argument.

* @throwsNumberFormatException

if the string does not contain a

*

parsable number.

*/

public static Double valueOf(String s) throws NumberFormatException {

return new Double(parseDouble(s));

}

/**

* 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

*/

public static Double valueOf(double d) {

return new Double(d);

}

/**

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

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

*

* @param

vthe value to be tested.

* @return

{@code true} if the value of the argument is NaN;

*

{@code false} otherwise.

*/

public static boolean isNaN(double v) {

return (v != v);

}

/**

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

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

*

* @param

vthe value to be tested.

* @return

{@code true} if the 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 {@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) <= DoubleConsts.MAX_VALUE;

}

/**

* The value of the Double.

*

* @serial

*/

private final double value;

/**

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

* represents the primitive {@code double} argument.

*

* @param

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

*/

public Double(double value) {

this.value = value;

}

/**

* 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

sa string to be converted to a {@code Double}.

* @throws

NumberFormatException

if the string does not contain a

*

parsable number.

* @see

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

*/

public Double(String s) throws NumberFormatException {

value = parseDouble(s);

}

/**

* 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 {@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 {@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 {@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 Conversions

* @since JDK1.1

*/

public byte byteValue() {

return (byte)value;

}

/**

* 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 Conversions

* @since JDK1.1

*/

public short shortValue() {

return (short)value;

}

/**

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

* after a narrowing primitive conversion.

* @jls 5.1.3 Narrowing Primitive Conversions

*

* @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 {@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 Conversions

*/

public long longValue() {

return (long)value;

}

/**

* 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 Conversions

* @since JDK1.0

*/

public float floatValue() {

return (float)value;

}

/**

* Returns the {@code double} value of this {@code Double} object.

*

* @return the {@code double} value represented by this object

*/

public double doubleValue() {

return value;

}

/**

* 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 {@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 {@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.

*

* <p>Note that in most cases, for two instances of class

* {@code Double}, {@code d1} and {@code d2}, the

* value of {@code d1.equals(d2)} is {@code true} if and

* only if

*

* <blockquote>

*

{@code d1.doubleValue() == d2.doubleValue()}

* </blockquote>

*

* <p>also has the value {@code true}. However, there are two

* exceptions:

* <ul>

* <li>If {@code d1} and {@code d2} both represent

*{@code Double.NaN}, then the {@code equals} method

*returns {@code true}, even though

*{@code Double.NaN==Double.NaN} has the value

*{@code false}.

* <li>If {@code d1} represents {@code +0.0} while

*{@code d2} represents {@code -0.0}, or vice versa,

*the {@code equal} test has the value {@code false},

*even though {@code +0.0==-0.0} has the value {@code true}.

* </ul>

* This definition allows hash tables to operate properly.

* @param

objthe object to compare with.

* @return

{@code true} if the objects are the same;

*

{@code false} otherwise.

* @see java.lang.Double#doubleToLongBits(double)

*/

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.

*

* <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

valuea {@code double} precision floating-point number.

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

*/

public static long doubleToLongBits(double value) {

long result = doubleToRawLongBits(value);

// Check for NaN based on values of bit fields, maximum

// exponent and nonzero significand.

if ( ((result & DoubleConsts.EXP_BIT_MASK) ==

DoubleConsts.EXP_BIT_MASK) &&

(result & DoubleConsts.SIGNIF_BIT_MASK) != 0L)

result = 0x7ff8000000000000L;

return result;

}

/**

* 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

valuea {@code double} precision floating-point number.

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

* @since 1.3

*/

public static native long doubleToRawLongBits(double value);

/**

* 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>·<i>m</i>·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

bitsany {@code long} integer.

* @return

the {@code double} floating-point value with the same

*

bit pattern.

*/

public static native double longBitsToDouble(long bits);

/**

* Compares two {@code Double} objects numerically.

There

* are two ways in which comparisons performed by this method

* differ from those performed by the Java language numerical

* comparison operators ({@code <, <=, ==, >=, >})

* when applied to primitive {@code double} values:

* <ul><li>

*

{@code Double.NaN} is considered by this method

*

to be equal to itself and greater than all other

*

{@code double} values (including

*

{@code Double.POSITIVE_INFINITY}).

* <li>

*

{@code 0.0d} is considered by this method to be greater

*

than {@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>.

*

* @param

anotherDoublethe {@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}.

*

* @since

1.2

*/

public int compareTo(Double anotherDouble) {

return Double.compare(value, anotherDouble.value);

}

/**

* 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 {@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

*

* @since 1.8

*/

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

return a + b;

}

/**

* 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}

*

* @since 1.8

*/

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

return Math.max(a, b);

}

/**

* 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}.

*

* @since 1.8

*/

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

return Math.min(a, b);

}

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

private static final long serialVersionUID = -9172774392245257468L;

}