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/* * @(#)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; }
