/*
* @(#)Double.java 1.100 06/04/07
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.lang;
import sun.misc.FloatingDecimal;
import sun.misc.FpUtils;
import sun.misc.DoubleConsts;
/**
* The <code>Double</code> class wraps a value of the primitive type
* <code>double</code> in an object. An object of type
* <code>Double</code> contains a single field whose type is
* <code>double</code>.
* <p>
* In addition, this class provides several methods for converting a
* <code>double</code> to a <code>String</code> and a
* <code>String</code> to a <code>double</code>, as well as other
* constants and methods useful when dealing with a
* <code>double</code>.
*
* @author Lee Boynton
* @author Arthur van Hoff
* @author Joseph D. Darcy
* @version 1.100, 04/07/06
* @since JDK1.0
*/
public final class Double extends Number implements Comparable<Double> {
/**
* A constant holding the positive infinity of type
* <code>double</code>. It is equal to the value returned by
* <code>Double.longBitsToDouble(0x7ff0000000000000L)</code>.
*/
public static final double POSITIVE_INFINITY = 1.0 / 0.0;
/**
* A constant holding the negative infinity of type
* <code>double</code>. It is equal to the value returned by
* <code>Double.longBitsToDouble(0xfff0000000000000L)</code>.
*/
public static final double NEGATIVE_INFINITY = -1.0 / 0.0;
/**
* A constant holding a Not-a-Number (NaN) value of type
* <code>double</code>. It is equivalent to the value returned by
* <code>Double.longBitsToDouble(0x7ff8000000000000L)</code>.
*/
public static final double NaN = 0.0d / 0.0;
/**
* A constant holding the largest positive finite value of type
* <code>double</code>,
* (2-2<sup>-52</sup>)·2<sup>1023</sup>. It is equal to
* the hexadecimal floating-point literal
* <code>0x1.fffffffffffffP+1023</code> and also equal to
* <code>Double.longBitsToDouble(0x7fefffffffffffffL)</code>.
*/
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</code>, 2<sup>-1074</sup>. It is equal to the
* hexadecimal floating-point literal
* <code>0x0.0000000000001P-1022</code> and also equal to
* <code>Double.longBitsToDouble(0x1L)</code>.
*/
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 <tt>double</tt> value.
*
* @since 1.5
*/
public static final int SIZE = 64;
/**
* The <code>Class</code> instance representing the primitive type
* <code>double</code>.
*
* @since JDK1.1
*/
public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double");
/**
* Returns a string representation of the <code>double</code>
* argument. All characters mentioned below are ASCII characters.
* <ul>
* <li>If the argument is NaN, the result is the string
* "<code>NaN</code>".
* <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>'
* (<code>'\u002D'</code>); 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"</code>; thus, positive infinity produces the result
* <code>"Infinity"</code> and negative infinity produces the result
* <code>"-Infinity"</code>.
*
* <li>If <i>m</i> is zero, it is represented by the characters
* <code>"0.0"</code>; thus, negative zero produces the result
* <code>"-0.0"</code> and positive zero produces the result
* <code>"0.0"</code>.
*
* <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>' (<code>'\u002E'</code>), 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> <
* 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> < 10. The
* magnitude is then represented as the integer part of <i>a</i>,
* as a single decimal digit, followed by '<code>.</code>'
* (<code>'\u002E'</code>), followed by decimal digits
* representing the fractional part of <i>a</i>, followed by the
* letter '<code>E</code>' (<code>'\u0045'</code>), 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</code>. 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</code> value nearest
* to <i>x</i>; or if two <code>double</code> 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</code>.
* <p>
* To create localized string representations of a floating-point
* value, use subclasses of {@link java.text.NumberFormat}.
*
* @param d the <code>double</code> to be converted.
* @return a string representation of the argument.
*/
public static String toString(double d) {
return new FloatingDecimal(d).toJavaFormatString();
}
/**
* Returns a hexadecimal string representation of the
* <code>double</code> argument. All characters mentioned below
* are ASCII characters.
*
* <ul>
* <li>If the argument is NaN, the result is the string
* "<code>NaN</code>".
* <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>'
* (<code>'\u002D'</code>); 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"</code>; thus, positive infinity produces the
* result <code>"Infinity"</code> and negative infinity produces
* the result <code>"-Infinity"</code>.
*
* <li>If <i>m</i> is zero, it is represented by the string
* <code>"0x0.0p0"</code>; thus, negative zero produces the result
* <code>"-0x0.0p0"</code> and positive zero produces the result
* <code>"0x0.0p0"</code>.
*
* <li>If <i>m</i> is a <code>double</code> value with a
* normalized representation, substrings are used to represent the
* significand and exponent fields. The significand is
* represented by the characters <code>"0x1."</code>
* 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"</code> 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</code> value with a subnormal
* representation, the significand is represented by the
* characters <code>"0x0."</code> 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"</code>. Note that there must be at
* least one nonzero digit in a subnormal significand.
*
* </ul>
*
* </ul>
*
* <table border>
* <caption><h3>Examples</h3></caption>
* <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
* <tr><td><code>1.0</code></td> <td><code>0x1.0p0</code></td>
* <tr><td><code>-1.0</code></td> <td><code>-0x1.0p0</code></td>
* <tr><td><code>2.0</code></td> <td><code>0x1.0p1</code></td>
* <tr><td><code>3.0</code></td> <td><code>0x1.8p1</code></td>
* <tr><td><code>0.5</code></td> <td><code>0x1.0p-1</code></td>
* <tr><td><code>0.25</code></td> <td><code>0x1.0p-2</code></td>
* <tr><td><code>Double.MAX_VALUE</code></td>
* <td><code>0x1.fffffffffffffp1023</code></td>
* <tr><td><code>Minimum Normal Value</code></td>
* <td><code>0x1.0p-1022</code></td>
* <tr><td><code>Maximum Subnormal Value</code></td>
* <td><code>0x0.fffffffffffffp-1022</code></td>
* <tr><td><code>Double.MIN_VALUE</code></td>
* <td><code>0x0.0000000000001p-1022</code></td>
* </table>
* @param d the <code>double</code> 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 (!FpUtils.isFinite(d) )
// For infinity and NaN, use the decimal output.
return Double.toString(d);
else {
// Initialized to maximum size of output.
StringBuffer answer = new StringBuffer(24);
if (FpUtils.rawCopySign(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}$", ""));
// 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("p" + (subnormal ?
DoubleConsts.MIN_EXPONENT:
FpUtils.getExponent(d) ));
}
return answer.toString();
}
}
/**
* Returns a <code>Double</code> object holding the
* <code>double</code> value represented by the argument string
* <code>s</code>.
*
* <p>If <code>s</code> is <code>null</code>, then a
* <code>NullPointerException</code> is thrown.
*
* <p>Leading and trailing whitespace characters in <code>s</code>
* 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</code> 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</code>
* <dd><i>Sign<sub>opt</sub></i> <code>Infinity</code>
* <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
* <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
* <dd><i>SignedInteger</i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>HexFloatingPointLiteral</i>:
* <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>HexSignificand:</i>
* <dd><i>HexNumeral</i>
* <dd><i>HexNumeral</i> <code>.</code>
* <dd><code>0x</code> <i>HexDigits<sub>opt</sub>
* </i><code>.</code><i> HexDigits</i>
* <dd><code>0X</code><i> HexDigits<sub>opt</sub>
* </i><code>.</code> <i>HexDigits</i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>BinaryExponent:</i>
* <dd><i>BinaryExponentIndicator SignedInteger</i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>BinaryExponentIndicator:</i>
* <dd><code>p</code>
* <dd><code>P</code>
* </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 the of the <a
* href="http://java.sun.com/docs/books/jls/html/">Java Language
* Specification</a>. If <code>s</code> does not have the form of
* a <i>FloatValue</i>, then a <code>NumberFormatException</code>
* is thrown. Otherwise, <code>s</code> 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</code>
* by the usual round-to-nearest rule of IEEE 754 floating-point
* arithmetic, which includes preserving the sign of a zero
* value. Finally, a <code>Double</code> object representing this
* <code>double</code> 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</code> is a <code>float</code> value;
* <code>1.0d</code> is a <code>double</code> 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</code> followed
* by <code>float</code> to <code>double</code>, is <em>not</em>
* equivalent to converting a string directly to
* <code>double</code>. For example, the <code>float</code>
* literal <code>0.1f</code> is equal to the <code>double</code>
* value <code>0.10000000149011612</code>; the <code>float</code>
* literal <code>0.1f</code> represents a different numerical
* value than the <code>double</code> literal
* <code>0.1</code>. (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</code> be thrown, the regular
* expression below can be used to screen the input string:
*
* <code>
* <pre>
* 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 the Java Language Specification, 2nd
* // edition, section 3.10.2.
*
* // 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>
* </code>
*
* @param s the string to be parsed.
* @return a <code>Double</code> object holding the value
* represented by the <code>String</code> argument.
* @exception NumberFormatException if the string does not contain a
* parsable number.
*/
public static Double valueOf(String s) throws NumberFormatException {
return new Double(FloatingDecimal.readJavaFormatString(s).doubleValue());
}
/**
* Returns a <tt>Double</tt> instance representing the specified
* <tt>double</tt> value.
* If a new <tt>Double</tt> 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 <tt>Double</tt> instance representing <tt>d</tt>.
* @since 1.5
*/
public static Double valueOf(double d) {
return new Double(d);
}
/**
* Returns a new <code>double</code> initialized to the value
* represented by the specified <code>String</code>, as performed
* by the <code>valueOf</code> method of class
* <code>Double</code>.
*
* @param s the string to be parsed.
* @return the <code>double</code> value represented by the string
* argument.
* @exception NumberFormatException if the string does not contain
* a parsable <code>double</code>.
* @see java.lang.Double#valueOf(String)
* @since 1.2
*/
public static double parseDouble(String s) throws NumberFormatException {
return FloatingDecimal.readJavaFormatString(s).doubleValue();
}
/**
* Returns <code>true</code> if the specified number is a
* Not-a-Number (NaN) value, <code>false</code> otherwise.
*
* @param v the value to be tested.
* @return <code>true</code> if the value of the argument is NaN;
* <code>false</code> otherwise.
*/
static public boolean isNaN(double v) {
return (v != v);
}
/**
* Returns <code>true</code> if the specified number is infinitely
* large in magnitude, <code>false</code> otherwise.
*
* @param v the value to be tested.
* @return <code>true</code> if the value of the argument is positive
* infinity or negative infinity; <code>false</code> otherwise.
*/
static public boolean isInfinite(double v) {
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
}
/**
* The value of the Double.
*
* @serial
*/
private final double value;
/**
* Constructs a newly allocated <code>Double</code> object that
* represents the primitive <code>double</code> argument.
*
* @param value the value to be represented by the <code>Double</code>.
*/
public Double(double value) {
this.value = value;
}
/**
* Constructs a newly allocated <code>Double</code> object that
* represents the floating-point value of type <code>double</code>
* represented by the string. The string is converted to a
* <code>double</code> value as if by the <code>valueOf</code> method.
*
* @param s a string to be converted to a <code>Double</code>.
* @exception NumberFormatException if the string does not contain a
* parsable number.
* @see java.lang.Double#valueOf(java.lang.String)
*/
public Double(String s) throws NumberFormatException {
// REMIND: this is inefficient
this(valueOf(s).doubleValue());
}
/**
* Returns <code>true</code> if this <code>Double</code> value is
* a Not-a-Number (NaN), <code>false</code> otherwise.
*
* @return <code>true</code> if the value represented by this object is
* NaN; <code>false</code> otherwise.
*/
public boolean isNaN() {
return isNaN(value);
}
/**
* Returns <code>true</code> if this <code>Double</code> value is
* infinitely large in magnitude, <code>false</code> otherwise.
*
* @return <code>true</code> if the value represented by this object is
* positive infinity or negative infinity;
* <code>false</code> otherwise.
*/
public boolean isInfinite() {
return isInfinite(value);
}
/**
* Returns a string representation of this <code>Double</code> object.
* The primitive <code>double</code> value represented by this
* object is converted to a string exactly as if by the method
* <code>toString</code> of one argument.
*
* @return a <code>String</code> representation of this object.
* @see java.lang.Double#toString(double)
*/
public String toString() {
return String.valueOf(value);
}
/**
* Returns the value of this <code>Double</code> as a <code>byte</code> (by
* casting to a <code>byte</code>).
*
* @return the <code>double</code> value represented by this object
* converted to type <code>byte</code>
* @since JDK1.1
*/
public byte byteValue() {
return (byte)value;
}
/**
* Returns the value of this <code>Double</code> as a
* <code>short</code> (by casting to a <code>short</code>).
*
* @return the <code>double</code> value represented by this object
* converted to type <code>short</code>
* @since JDK1.1
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this <code>Double</code> as an
* <code>int</code> (by casting to type <code>int</code>).
*
* @return the <code>double</code> value represented by this object
* converted to type <code>int</code>
*/
public int intValue() {
return (int)value;
}
/**
* Returns the value of this <code>Double</code> as a
* <code>long</code> (by casting to type <code>long</code>).
*
* @return the <code>double</code> value represented by this object
* converted to type <code>long</code>
*/
public long longValue() {
return (long)value;
}
/**
* Returns the <code>float</code> value of this
* <code>Double</code> object.
*
* @return the <code>double</code> value represented by this object
* converted to type <code>float</code>
* @since JDK1.0
*/
public float floatValue() {
return (float)value;
}
/**
* Returns the <code>double</code> value of this
* <code>Double</code> object.
*
* @return the <code>double</code> value represented by this object
*/
public double doubleValue() {
return (double)value;
}
/**
* Returns a hash code for this <code>Double</code> object. The
* result is the exclusive OR of the two halves of the
* <code>long</code> integer bit representation, exactly as
* produced by the method {@link #doubleToLongBits(double)}, of
* the primitive <code>double</code> value represented by this
* <code>Double</code> object. That is, the hash code is the value
* of the expression:
* <blockquote><pre>
* (int)(v^(v>>>32))
* </pre></blockquote>
* where <code>v</code> is defined by:
* <blockquote><pre>
* long v = Double.doubleToLongBits(this.doubleValue());
* </pre></blockquote>
*
* @return a <code>hash code</code> value for this object.
*/
public int hashCode() {
long bits = doubleToLongBits(value);
return (int)(bits ^ (bits >>> 32));
}
/**
* Compares this object against the specified object. The result
* is <code>true</code> if and only if the argument is not
* <code>null</code> and is a <code>Double</code> object that
* represents a <code>double</code> that has the same value as the
* <code>double</code> represented by this object. For this
* purpose, two <code>double</code> values are considered to be
* the same if and only if the method {@link
* #doubleToLongBits(double)} returns the identical
* <code>long</code> value when applied to each.
* <p>
* Note that in most cases, for two instances of class
* <code>Double</code>, <code>d1</code> and <code>d2</code>, the
* value of <code>d1.equals(d2)</code> is <code>true</code> if and
* only if
* <blockquote><pre>
* d1.doubleValue() == d2.doubleValue()
* </pre></blockquote>
* <p>
* also has the value <code>true</code>. However, there are two
* exceptions:
* <ul>
* <li>If <code>d1</code> and <code>d2</code> both represent
* <code>Double.NaN</code>, then the <code>equals</code> method
* returns <code>true</code>, even though
* <code>Double.NaN==Double.NaN</code> has the value
* <code>false</code>.
* <li>If <code>d1</code> represents <code>+0.0</code> while
* <code>d2</code> represents <code>-0.0</code>, or vice versa,
* the <code>equal</code> test has the value <code>false</code>,
* even though <code>+0.0==-0.0</code> has the value <code>true</code>.
* </ul>
* This definition allows hash tables to operate properly.
* @param obj the object to compare with.
* @return <code>true</code> if the objects are the same;
* <code>false</code> 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</code>) represents the sign of the
* floating-point number. Bits
* 62-52 (the bits that are selected by the mask
* <code>0x7ff0000000000000L</code>) represent the exponent. Bits 51-0
* (the bits that are selected by the mask
* <code>0x000fffffffffffffL</code>) represent the significand
* (sometimes called the mantissa) of the floating-point number.
* <p>
* If the argument is positive infinity, the result is
* <code>0x7ff0000000000000L</code>.
* <p>
* If the argument is negative infinity, the result is
* <code>0xfff0000000000000L</code>.
* <p>
* If the argument is NaN, the result is
* <code>0x7ff8000000000000L</code>.
* <p>
* In all cases, the result is a <code>long</code> integer that, when
* given to the {@link #longBitsToDouble(long)} method, will produce a
* floating-point value the same as the argument to
* <code>doubleToLongBits</code> (except all NaN values are
* collapsed to a single "canonical" NaN value).
*
* @param value a <code>double</code> 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</code>) represents the sign of the
* floating-point number. Bits
* 62-52 (the bits that are selected by the mask
* <code>0x7ff0000000000000L</code>) represent the exponent. Bits 51-0
* (the bits that are selected by the mask
* <code>0x000fffffffffffffL</code>) represent the significand
* (sometimes called the mantissa) of the floating-point number.
* <p>
* If the argument is positive infinity, the result is
* <code>0x7ff0000000000000L</code>.
* <p>
* If the argument is negative infinity, the result is
* <code>0xfff0000000000000L</code>.
* <p>
* If the argument is NaN, the result is the <code>long</code>
* integer representing the actual NaN value. Unlike the
* <code>doubleToLongBits</code> method,
* <code>doubleToRawLongBits</code> 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</code> integer that,
* when given to the {@link #longBitsToDouble(long)} method, will
* produce a floating-point value the same as the argument to
* <code>doubleToRawLongBits</code>.
*
* @param value a <code>double</code> 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</code> 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</code>, the result
* is positive infinity.
* <p>
* If the argument is <code>0xfff0000000000000L</code>, the result
* is negative infinity.
* <p>
* If the argument is any value in the range
* <code>0x7ff0000000000001L</code> through
* <code>0x7fffffffffffffffL</code> or in the range
* <code>0xfff0000000000001L</code> through
* <code>0xffffffffffffffffL</code>, 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</code> 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>
* 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</code> NaN with exactly same bit pattern as the
* <code>long</code> 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</code>
* may not be able to return a <code>double</code> with a
* signaling NaN bit pattern. Consequently, for some
* <code>long</code> values,
* <code>doubleToRawLongBits(longBitsToDouble(start))</code> may
* <i>not</i> equal <code>start</code>. 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</code> integer.
* @return the <code>double</code> floating-point value with the same
* bit pattern.
*/
public static native double longBitsToDouble(long bits);
/**
* Compares two <code>Double</code> 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><, <=, ==, >= ></code>)
* when applied to primitive <code>double</code> values:
* <ul><li>
* <code>Double.NaN</code> is considered by this method
* to be equal to itself and greater than all other
* <code>double</code> values (including
* <code>Double.POSITIVE_INFINITY</code>).
* <li>
* <code>0.0d</code> is considered by this method to be greater
* than <code>-0.0d</code>.
* </ul>
* This ensures that the <i>natural ordering</i> of
* <tt>Double</tt> objects imposed by this method is <i>consistent
* with equals</i>.
*
* @param anotherDouble the <code>Double</code> to be compared.
* @return the value <code>0</code> if <code>anotherDouble</code> is
* numerically equal to this <code>Double</code>; a value
* less than <code>0</code> if this <code>Double</code>
* is numerically less than <code>anotherDouble</code>;
* and a value greater than <code>0</code> if this
* <code>Double</code> is numerically greater than
* <code>anotherDouble</code>.
*
* @since 1.2
*/
public int compareTo(Double anotherDouble) {
return Double.compare(value, anotherDouble.value);
}
/**
* Compares the two specified <code>double</code> 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</code> to compare
* @param d2 the second <code>double</code> to compare
* @return the value <code>0</code> if <code>d1</code> is
* numerically equal to <code>d2</code>; a value less than
* <code>0</code> if <code>d1</code> is numerically less than
* <code>d2</code>; and a value greater than <code>0</code>
* if <code>d1</code> is numerically greater than
* <code>d2</code>.
* @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
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)
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = -9172774392245257468L;
}
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