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The Double.java Java example source code
/*
* 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)·21023. 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. 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. 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) 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:
* <ul>
* <li>If m 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 m 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 m is greater than or equal to 10-3 but less
* than 10<sup>7, then it is represented as the integer part of
* <i>m, 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.
*
* <li>If m is less than 10-3 or greater than or
* equal to 10<sup>7, then it is represented in so-called
* "computerized scientific notation." Let <i>n be the unique
* integer such that 10<sup>n ≤ m {@literal <}
* 10<sup>n+1; then let a be the
* mathematically exact quotient of <i>m and
* 10<sup>n so that 1 ≤ a {@literal <} 10. The
* magnitude is then represented as the integer part of <i>a,
* as a single decimal digit, followed by '{@code .}'
* ({@code '\u005Cu002E'}), followed by decimal digits
* representing the fractional part of <i>a, followed by the
* letter '{@code E}' ({@code '\u005Cu0045'}), followed
* by a representation of <i>n 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 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 {@code double}. That is, suppose that
* <i>x is the exact mathematical value represented by the decimal
* representation produced by this method for a finite nonzero argument
* <i>d. Then d must be the {@code double} value nearest
* to <i>x; or if two {@code double} values are equally close
* to <i>x, then d must be one of them and the least
* significant bit of the significand of <i>d 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
* {@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:
*
* <ul>
* <li>If m 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 m 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 m 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 m 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
* <tr>| Floating-point Value | Hexadecimal String |
* <tr>{@code 1.0} | {@code 0x1.0p0} |
* <tr>{@code -1.0} | {@code -0x1.0p0} |
* <tr>{@code 2.0} | {@code 0x1.0p1} |
* <tr>{@code 3.0} | {@code 0x1.8p1} |
* <tr>{@code 0.5} | {@code 0x1.0p-1} |
* <tr>{@code 0.25} | {@code 0x1.0p-2} |
* <tr>{@code Double.MAX_VALUE} |
* <td>{@code 0x1.fffffffffffffp1023} |
* <tr>{@code Minimum Normal Value} |
* <td>{@code 0x1.0p-1022}
* <tr>{@code Maximum Subnormal Value} |
* <td>{@code 0x0.fffffffffffffp-1022}
* <tr>{@code Double.MIN_VALUE} |
* <td>{@code 0x0.0000000000001p-1022}
* </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 < 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 as described by the lexical
* syntax rules:
*
* <blockquote>
* <dl>
* <dt>FloatValue:
* <dd>Signopt {@code NaN}
* <dd>Signopt {@code Infinity}
* <dd>Signopt FloatingPointLiteral
* <dd>Signopt HexFloatingPointLiteral
* <dd>SignedInteger
* </dl>
*
* <dl>
* <dt>HexFloatingPointLiteral:
* <dd> HexSignificand BinaryExponent FloatTypeSuffixopt
* </dl>
*
* <dl>
* <dt>HexSignificand:
* <dd>HexNumeral
* <dd>HexNumeral {@code .}
* <dd>{@code 0x} HexDigitsopt
* </i>{@code .} HexDigits
* <dd>{@code 0X} HexDigitsopt
* </i>{@code .} HexDigits
* </dl>
*
* <dl>
* <dt>BinaryExponent:
* <dd>BinaryExponentIndicator SignedInteger
* </dl>
*
* <dl>
* <dt>BinaryExponentIndicator:
* <dd>{@code p}
* <dd>{@code P}
* </dl>
*
* </blockquote>
*
* where <i>Sign, FloatingPointLiteral,
* <i>HexNumeral, HexDigits, SignedInteger and
* <i>FloatTypeSuffix are as defined in the lexical structure
* sections of
* <cite>The Java™ Language Specification,
* except that underscores are not accepted between digits.
* If {@code s} does not have the form of
* a <i>FloatValue, 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 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
* 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 {@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 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 {@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 {@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 value the 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 s a 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 obj the 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 value a {@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 value a {@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 s, e, and m be three
* values that can be computed from the argument:
*
* <blockquote>{@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>
*
* Then the floating-point result equals the value of the mathematical
* expression <i>s·m·2e-1075.
*
* <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. 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 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.
*/
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>
* {@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 of
* {@code Double} objects imposed by this method is <i>consistent
* with equals</i>.
*
* @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}.
*
* @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
* @see java.util.function.BinaryOperator
* @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}
* @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 {@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);
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = -9172774392245257468L;
}
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