001: /*
002: * Copyright 1994-2006 Sun Microsystems, Inc. All Rights Reserved.
003: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004: *
005: * This code is free software; you can redistribute it and/or modify it
006: * under the terms of the GNU General Public License version 2 only, as
007: * published by the Free Software Foundation. Sun designates this
008: * particular file as subject to the "Classpath" exception as provided
009: * by Sun in the LICENSE file that accompanied this code.
010: *
011: * This code is distributed in the hope that it will be useful, but WITHOUT
012: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014: * version 2 for more details (a copy is included in the LICENSE file that
015: * accompanied this code).
016: *
017: * You should have received a copy of the GNU General Public License version
018: * 2 along with this work; if not, write to the Free Software Foundation,
019: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020: *
021: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022: * CA 95054 USA or visit www.sun.com if you need additional information or
023: * have any questions.
024: */
025:
026: package java.lang;
027:
028: import sun.misc.FloatingDecimal;
029: import sun.misc.FpUtils;
030: import sun.misc.DoubleConsts;
031:
032: /**
033: * The {@code Double} class wraps a value of the primitive type
034: * {@code double} in an object. An object of type
035: * {@code Double} contains a single field whose type is
036: * {@code double}.
037: *
038: * <p>In addition, this class provides several methods for converting a
039: * {@code double} to a {@code String} and a
040: * {@code String} to a {@code double}, as well as other
041: * constants and methods useful when dealing with a
042: * {@code double}.
043: *
044: * @author Lee Boynton
045: * @author Arthur van Hoff
046: * @author Joseph D. Darcy
047: * @version 1.108, 06/12/07
048: * @since JDK1.0
049: */
050: public final class Double extends Number implements Comparable<Double> {
051: /**
052: * A constant holding the positive infinity of type
053: * {@code double}. It is equal to the value returned by
054: * {@code Double.longBitsToDouble(0x7ff0000000000000L)}.
055: */
056: public static final double POSITIVE_INFINITY = 1.0 / 0.0;
057:
058: /**
059: * A constant holding the negative infinity of type
060: * {@code double}. It is equal to the value returned by
061: * {@code Double.longBitsToDouble(0xfff0000000000000L)}.
062: */
063: public static final double NEGATIVE_INFINITY = -1.0 / 0.0;
064:
065: /**
066: * A constant holding a Not-a-Number (NaN) value of type
067: * {@code double}. It is equivalent to the value returned by
068: * {@code Double.longBitsToDouble(0x7ff8000000000000L)}.
069: */
070: public static final double NaN = 0.0d / 0.0;
071:
072: /**
073: * A constant holding the largest positive finite value of type
074: * {@code double},
075: * (2-2<sup>-52</sup>)·2<sup>1023</sup>. It is equal to
076: * the hexadecimal floating-point literal
077: * {@code 0x1.fffffffffffffP+1023} and also equal to
078: * {@code Double.longBitsToDouble(0x7fefffffffffffffL)}.
079: */
080: public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308
081:
082: /**
083: * A constant holding the smallest positive normal value of type
084: * {@code double}, 2<sup>-1022</sup>. It is equal to the
085: * hexadecimal floating-point literal {@code 0x1.0p-1022} and also
086: * equal to {@code Double.longBitsToDouble(0x0010000000000000L)}.
087: *
088: * @since 1.6
089: */
090: public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308
091:
092: /**
093: * A constant holding the smallest positive nonzero value of type
094: * {@code double}, 2<sup>-1074</sup>. It is equal to the
095: * hexadecimal floating-point literal
096: * {@code 0x0.0000000000001P-1022} and also equal to
097: * {@code Double.longBitsToDouble(0x1L)}.
098: */
099: public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324
100:
101: /**
102: * Maximum exponent a finite {@code double} variable may have.
103: * It is equal to the value returned by
104: * {@code Math.getExponent(Double.MAX_VALUE)}.
105: *
106: * @since 1.6
107: */
108: public static final int MAX_EXPONENT = 1023;
109:
110: /**
111: * Minimum exponent a normalized {@code double} variable may
112: * have. It is equal to the value returned by
113: * {@code Math.getExponent(Double.MIN_NORMAL)}.
114: *
115: * @since 1.6
116: */
117: public static final int MIN_EXPONENT = -1022;
118:
119: /**
120: * The number of bits used to represent a {@code double} value.
121: *
122: * @since 1.5
123: */
124: public static final int SIZE = 64;
125:
126: /**
127: * The {@code Class} instance representing the primitive type
128: * {@code double}.
129: *
130: * @since JDK1.1
131: */
132: public static final Class<Double> TYPE = (Class<Double>) Class
133: .getPrimitiveClass("double");
134:
135: /**
136: * Returns a string representation of the {@code double}
137: * argument. All characters mentioned below are ASCII characters.
138: * <ul>
139: * <li>If the argument is NaN, the result is the string
140: * "{@code NaN}".
141: * <li>Otherwise, the result is a string that represents the sign and
142: * magnitude (absolute value) of the argument. If the sign is negative,
143: * the first character of the result is '{@code -}'
144: * (<code>'\u002D'</code>); if the sign is positive, no sign character
145: * appears in the result. As for the magnitude <i>m</i>:
146: * <ul>
147: * <li>If <i>m</i> is infinity, it is represented by the characters
148: * {@code "Infinity"}; thus, positive infinity produces the result
149: * {@code "Infinity"} and negative infinity produces the result
150: * {@code "-Infinity"}.
151: *
152: * <li>If <i>m</i> is zero, it is represented by the characters
153: * {@code "0.0"}; thus, negative zero produces the result
154: * {@code "-0.0"} and positive zero produces the result
155: * {@code "0.0"}.
156: *
157: * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less
158: * than 10<sup>7</sup>, then it is represented as the integer part of
159: * <i>m</i>, in decimal form with no leading zeroes, followed by
160: * '{@code .}' (<code>'\u002E'</code>), followed by one or
161: * more decimal digits representing the fractional part of <i>m</i>.
162: *
163: * <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or
164: * equal to 10<sup>7</sup>, then it is represented in so-called
165: * "computerized scientific notation." Let <i>n</i> be the unique
166: * integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <}
167: * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the
168: * mathematically exact quotient of <i>m</i> and
169: * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The
170: * magnitude is then represented as the integer part of <i>a</i>,
171: * as a single decimal digit, followed by '{@code .}'
172: * (<code>'\u002E'</code>), followed by decimal digits
173: * representing the fractional part of <i>a</i>, followed by the
174: * letter '{@code E}' (<code>'\u0045'</code>), followed
175: * by a representation of <i>n</i> as a decimal integer, as
176: * produced by the method {@link Integer#toString(int)}.
177: * </ul>
178: * </ul>
179: * How many digits must be printed for the fractional part of
180: * <i>m</i> or <i>a</i>? There must be at least one digit to represent
181: * the fractional part, and beyond that as many, but only as many, more
182: * digits as are needed to uniquely distinguish the argument value from
183: * adjacent values of type {@code double}. That is, suppose that
184: * <i>x</i> is the exact mathematical value represented by the decimal
185: * representation produced by this method for a finite nonzero argument
186: * <i>d</i>. Then <i>d</i> must be the {@code double} value nearest
187: * to <i>x</i>; or if two {@code double} values are equally close
188: * to <i>x</i>, then <i>d</i> must be one of them and the least
189: * significant bit of the significand of <i>d</i> must be {@code 0}.
190: *
191: * <p>To create localized string representations of a floating-point
192: * value, use subclasses of {@link java.text.NumberFormat}.
193: *
194: * @param d the {@code double} to be converted.
195: * @return a string representation of the argument.
196: */
197: public static String toString(double d) {
198: return new FloatingDecimal(d).toJavaFormatString();
199: }
200:
201: /**
202: * Returns a hexadecimal string representation of the
203: * {@code double} argument. All characters mentioned below
204: * are ASCII characters.
205: *
206: * <ul>
207: * <li>If the argument is NaN, the result is the string
208: * "{@code NaN}".
209: * <li>Otherwise, the result is a string that represents the sign
210: * and magnitude of the argument. If the sign is negative, the
211: * first character of the result is '{@code -}'
212: * (<code>'\u002D'</code>); if the sign is positive, no sign
213: * character appears in the result. As for the magnitude <i>m</i>:
214: *
215: * <ul>
216: * <li>If <i>m</i> is infinity, it is represented by the string
217: * {@code "Infinity"}; thus, positive infinity produces the
218: * result {@code "Infinity"} and negative infinity produces
219: * the result {@code "-Infinity"}.
220: *
221: * <li>If <i>m</i> is zero, it is represented by the string
222: * {@code "0x0.0p0"}; thus, negative zero produces the result
223: * {@code "-0x0.0p0"} and positive zero produces the result
224: * {@code "0x0.0p0"}.
225: *
226: * <li>If <i>m</i> is a {@code double} value with a
227: * normalized representation, substrings are used to represent the
228: * significand and exponent fields. The significand is
229: * represented by the characters {@code "0x1."}
230: * followed by a lowercase hexadecimal representation of the rest
231: * of the significand as a fraction. Trailing zeros in the
232: * hexadecimal representation are removed unless all the digits
233: * are zero, in which case a single zero is used. Next, the
234: * exponent is represented by {@code "p"} followed
235: * by a decimal string of the unbiased exponent as if produced by
236: * a call to {@link Integer#toString(int) Integer.toString} on the
237: * exponent value.
238: *
239: * <li>If <i>m</i> is a {@code double} value with a subnormal
240: * representation, the significand is represented by the
241: * characters {@code "0x0."} followed by a
242: * hexadecimal representation of the rest of the significand as a
243: * fraction. Trailing zeros in the hexadecimal representation are
244: * removed. Next, the exponent is represented by
245: * {@code "p-1022"}. Note that there must be at
246: * least one nonzero digit in a subnormal significand.
247: *
248: * </ul>
249: *
250: * </ul>
251: *
252: * <table border>
253: * <caption><h3>Examples</h3></caption>
254: * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
255: * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
256: * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
257: * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
258: * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
259: * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
260: * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
261: * <tr><td>{@code Double.MAX_VALUE}</td>
262: * <td>{@code 0x1.fffffffffffffp1023}</td>
263: * <tr><td>{@code Minimum Normal Value}</td>
264: * <td>{@code 0x1.0p-1022}</td>
265: * <tr><td>{@code Maximum Subnormal Value}</td>
266: * <td>{@code 0x0.fffffffffffffp-1022}</td>
267: * <tr><td>{@code Double.MIN_VALUE}</td>
268: * <td>{@code 0x0.0000000000001p-1022}</td>
269: * </table>
270: * @param d the {@code double} to be converted.
271: * @return a hex string representation of the argument.
272: * @since 1.5
273: * @author Joseph D. Darcy
274: */
275: public static String toHexString(double d) {
276: /*
277: * Modeled after the "a" conversion specifier in C99, section
278: * 7.19.6.1; however, the output of this method is more
279: * tightly specified.
280: */
281: if (!FpUtils.isFinite(d))
282: // For infinity and NaN, use the decimal output.
283: return Double.toString(d);
284: else {
285: // Initialized to maximum size of output.
286: StringBuffer answer = new StringBuffer(24);
287:
288: if (FpUtils.rawCopySign(1.0, d) == -1.0) // value is negative,
289: answer.append("-"); // so append sign info
290:
291: answer.append("0x");
292:
293: d = Math.abs(d);
294:
295: if (d == 0.0) {
296: answer.append("0.0p0");
297: } else {
298: boolean subnormal = (d < DoubleConsts.MIN_NORMAL);
299:
300: // Isolate significand bits and OR in a high-order bit
301: // so that the string representation has a known
302: // length.
303: long signifBits = (Double.doubleToLongBits(d) & DoubleConsts.SIGNIF_BIT_MASK) | 0x1000000000000000L;
304:
305: // Subnormal values have a 0 implicit bit; normal
306: // values have a 1 implicit bit.
307: answer.append(subnormal ? "0." : "1.");
308:
309: // Isolate the low-order 13 digits of the hex
310: // representation. If all the digits are zero,
311: // replace with a single 0; otherwise, remove all
312: // trailing zeros.
313: String signif = Long.toHexString(signifBits).substring(
314: 3, 16);
315: answer.append(signif.equals("0000000000000") ? // 13 zeros
316: "0"
317: : signif.replaceFirst("0{1,12}$", ""));
318:
319: // If the value is subnormal, use the E_min exponent
320: // value for double; otherwise, extract and report d's
321: // exponent (the representation of a subnormal uses
322: // E_min -1).
323: answer.append("p"
324: + (subnormal ? DoubleConsts.MIN_EXPONENT
325: : FpUtils.getExponent(d)));
326: }
327: return answer.toString();
328: }
329: }
330:
331: /**
332: * Returns a {@code Double} object holding the
333: * {@code double} value represented by the argument string
334: * {@code s}.
335: *
336: * <p>If {@code s} is {@code null}, then a
337: * {@code NullPointerException} is thrown.
338: *
339: * <p>Leading and trailing whitespace characters in {@code s}
340: * are ignored. Whitespace is removed as if by the {@link
341: * String#trim} method; that is, both ASCII space and control
342: * characters are removed. The rest of {@code s} should
343: * constitute a <i>FloatValue</i> as described by the lexical
344: * syntax rules:
345: *
346: * <blockquote>
347: * <dl>
348: * <dt><i>FloatValue:</i>
349: * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
350: * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
351: * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
352: * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
353: * <dd><i>SignedInteger</i>
354: * </dl>
355: *
356: * <p>
357: *
358: * <dl>
359: * <dt><i>HexFloatingPointLiteral</i>:
360: * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
361: * </dl>
362: *
363: * <p>
364: *
365: * <dl>
366: * <dt><i>HexSignificand:</i>
367: * <dd><i>HexNumeral</i>
368: * <dd><i>HexNumeral</i> {@code .}
369: * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
370: * </i>{@code .}<i> HexDigits</i>
371: * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
372: * </i>{@code .} <i>HexDigits</i>
373: * </dl>
374: *
375: * <p>
376: *
377: * <dl>
378: * <dt><i>BinaryExponent:</i>
379: * <dd><i>BinaryExponentIndicator SignedInteger</i>
380: * </dl>
381: *
382: * <p>
383: *
384: * <dl>
385: * <dt><i>BinaryExponentIndicator:</i>
386: * <dd>{@code p}
387: * <dd>{@code P}
388: * </dl>
389: *
390: * </blockquote>
391: *
392: * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
393: * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
394: * <i>FloatTypeSuffix</i> are as defined in the lexical structure
395: * sections of the <a
396: * href="http://java.sun.com/docs/books/jls/html/">Java Language
397: * Specification</a>. If {@code s} does not have the form of
398: * a <i>FloatValue</i>, then a {@code NumberFormatException}
399: * is thrown. Otherwise, {@code s} is regarded as
400: * representing an exact decimal value in the usual
401: * "computerized scientific notation" or as an exact
402: * hexadecimal value; this exact numerical value is then
403: * conceptually converted to an "infinitely precise"
404: * binary value that is then rounded to type {@code double}
405: * by the usual round-to-nearest rule of IEEE 754 floating-point
406: * arithmetic, which includes preserving the sign of a zero
407: * value. Finally, a {@code Double} object representing this
408: * {@code double} value is returned.
409: *
410: * <p> To interpret localized string representations of a
411: * floating-point value, use subclasses of {@link
412: * java.text.NumberFormat}.
413: *
414: * <p>Note that trailing format specifiers, specifiers that
415: * determine the type of a floating-point literal
416: * ({@code 1.0f} is a {@code float} value;
417: * {@code 1.0d} is a {@code double} value), do
418: * <em>not</em> influence the results of this method. In other
419: * words, the numerical value of the input string is converted
420: * directly to the target floating-point type. The two-step
421: * sequence of conversions, string to {@code float} followed
422: * by {@code float} to {@code double}, is <em>not</em>
423: * equivalent to converting a string directly to
424: * {@code double}. For example, the {@code float}
425: * literal {@code 0.1f} is equal to the {@code double}
426: * value {@code 0.10000000149011612}; the {@code float}
427: * literal {@code 0.1f} represents a different numerical
428: * value than the {@code double} literal
429: * {@code 0.1}. (The numerical value 0.1 cannot be exactly
430: * represented in a binary floating-point number.)
431: *
432: * <p>To avoid calling this method on an invalid string and having
433: * a {@code NumberFormatException} be thrown, the regular
434: * expression below can be used to screen the input string:
435: *
436: * <code>
437: * <pre>
438: * final String Digits = "(\\p{Digit}+)";
439: * final String HexDigits = "(\\p{XDigit}+)";
440: * // an exponent is 'e' or 'E' followed by an optionally
441: * // signed decimal integer.
442: * final String Exp = "[eE][+-]?"+Digits;
443: * final String fpRegex =
444: * ("[\\x00-\\x20]*"+ // Optional leading "whitespace"
445: * "[+-]?(" + // Optional sign character
446: * "NaN|" + // "NaN" string
447: * "Infinity|" + // "Infinity" string
448: *
449: * // A decimal floating-point string representing a finite positive
450: * // number without a leading sign has at most five basic pieces:
451: * // Digits . Digits ExponentPart FloatTypeSuffix
452: * //
453: * // Since this method allows integer-only strings as input
454: * // in addition to strings of floating-point literals, the
455: * // two sub-patterns below are simplifications of the grammar
456: * // productions from the Java Language Specification, 2nd
457: * // edition, section 3.10.2.
458: *
459: * // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
460: * "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
461: *
462: * // . Digits ExponentPart_opt FloatTypeSuffix_opt
463: * "(\\.("+Digits+")("+Exp+")?)|"+
464: *
465: * // Hexadecimal strings
466: * "((" +
467: * // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
468: * "(0[xX]" + HexDigits + "(\\.)?)|" +
469: *
470: * // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
471: * "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
472: *
473: * ")[pP][+-]?" + Digits + "))" +
474: * "[fFdD]?))" +
475: * "[\\x00-\\x20]*");// Optional trailing "whitespace"
476: *
477: * if (Pattern.matches(fpRegex, myString))
478: * Double.valueOf(myString); // Will not throw NumberFormatException
479: * else {
480: * // Perform suitable alternative action
481: * }
482: * </pre>
483: * </code>
484: *
485: * @param s the string to be parsed.
486: * @return a {@code Double} object holding the value
487: * represented by the {@code String} argument.
488: * @throws NumberFormatException if the string does not contain a
489: * parsable number.
490: */
491: public static Double valueOf(String s) throws NumberFormatException {
492: return new Double(FloatingDecimal.readJavaFormatString(s)
493: .doubleValue());
494: }
495:
496: /**
497: * Returns a {@code Double} instance representing the specified
498: * {@code double} value.
499: * If a new {@code Double} instance is not required, this method
500: * should generally be used in preference to the constructor
501: * {@link #Double(double)}, as this method is likely to yield
502: * significantly better space and time performance by caching
503: * frequently requested values.
504: *
505: * @param d a double value.
506: * @return a {@code Double} instance representing {@code d}.
507: * @since 1.5
508: */
509: public static Double valueOf(double d) {
510: return new Double(d);
511: }
512:
513: /**
514: * Returns a new {@code double} initialized to the value
515: * represented by the specified {@code String}, as performed
516: * by the {@code valueOf} method of class
517: * {@code Double}.
518: *
519: * @param s the string to be parsed.
520: * @return the {@code double} value represented by the string
521: * argument.
522: * @throws NumberFormatException if the string does not contain
523: * a parsable {@code double}.
524: * @see java.lang.Double#valueOf(String)
525: * @since 1.2
526: */
527: public static double parseDouble(String s)
528: throws NumberFormatException {
529: return FloatingDecimal.readJavaFormatString(s).doubleValue();
530: }
531:
532: /**
533: * Returns {@code true} if the specified number is a
534: * Not-a-Number (NaN) value, {@code false} otherwise.
535: *
536: * @param v the value to be tested.
537: * @return {@code true} if the value of the argument is NaN;
538: * {@code false} otherwise.
539: */
540: static public boolean isNaN(double v) {
541: return (v != v);
542: }
543:
544: /**
545: * Returns {@code true} if the specified number is infinitely
546: * large in magnitude, {@code false} otherwise.
547: *
548: * @param v the value to be tested.
549: * @return {@code true} if the value of the argument is positive
550: * infinity or negative infinity; {@code false} otherwise.
551: */
552: static public boolean isInfinite(double v) {
553: return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
554: }
555:
556: /**
557: * The value of the Double.
558: *
559: * @serial
560: */
561: private final double value;
562:
563: /**
564: * Constructs a newly allocated {@code Double} object that
565: * represents the primitive {@code double} argument.
566: *
567: * @param value the value to be represented by the {@code Double}.
568: */
569: public Double(double value) {
570: this .value = value;
571: }
572:
573: /**
574: * Constructs a newly allocated {@code Double} object that
575: * represents the floating-point value of type {@code double}
576: * represented by the string. The string is converted to a
577: * {@code double} value as if by the {@code valueOf} method.
578: *
579: * @param s a string to be converted to a {@code Double}.
580: * @throws NumberFormatException if the string does not contain a
581: * parsable number.
582: * @see java.lang.Double#valueOf(java.lang.String)
583: */
584: public Double(String s) throws NumberFormatException {
585: // REMIND: this is inefficient
586: this (valueOf(s).doubleValue());
587: }
588:
589: /**
590: * Returns {@code true} if this {@code Double} value is
591: * a Not-a-Number (NaN), {@code false} otherwise.
592: *
593: * @return {@code true} if the value represented by this object is
594: * NaN; {@code false} otherwise.
595: */
596: public boolean isNaN() {
597: return isNaN(value);
598: }
599:
600: /**
601: * Returns {@code true} if this {@code Double} value is
602: * infinitely large in magnitude, {@code false} otherwise.
603: *
604: * @return {@code true} if the value represented by this object is
605: * positive infinity or negative infinity;
606: * {@code false} otherwise.
607: */
608: public boolean isInfinite() {
609: return isInfinite(value);
610: }
611:
612: /**
613: * Returns a string representation of this {@code Double} object.
614: * The primitive {@code double} value represented by this
615: * object is converted to a string exactly as if by the method
616: * {@code toString} of one argument.
617: *
618: * @return a {@code String} representation of this object.
619: * @see java.lang.Double#toString(double)
620: */
621: public String toString() {
622: return String.valueOf(value);
623: }
624:
625: /**
626: * Returns the value of this {@code Double} as a {@code byte} (by
627: * casting to a {@code byte}).
628: *
629: * @return the {@code double} value represented by this object
630: * converted to type {@code byte}
631: * @since JDK1.1
632: */
633: public byte byteValue() {
634: return (byte) value;
635: }
636:
637: /**
638: * Returns the value of this {@code Double} as a
639: * {@code short} (by casting to a {@code short}).
640: *
641: * @return the {@code double} value represented by this object
642: * converted to type {@code short}
643: * @since JDK1.1
644: */
645: public short shortValue() {
646: return (short) value;
647: }
648:
649: /**
650: * Returns the value of this {@code Double} as an
651: * {@code int} (by casting to type {@code int}).
652: *
653: * @return the {@code double} value represented by this object
654: * converted to type {@code int}
655: */
656: public int intValue() {
657: return (int) value;
658: }
659:
660: /**
661: * Returns the value of this {@code Double} as a
662: * {@code long} (by casting to type {@code long}).
663: *
664: * @return the {@code double} value represented by this object
665: * converted to type {@code long}
666: */
667: public long longValue() {
668: return (long) value;
669: }
670:
671: /**
672: * Returns the {@code float} value of this
673: * {@code Double} object.
674: *
675: * @return the {@code double} value represented by this object
676: * converted to type {@code float}
677: * @since JDK1.0
678: */
679: public float floatValue() {
680: return (float) value;
681: }
682:
683: /**
684: * Returns the {@code double} value of this
685: * {@code Double} object.
686: *
687: * @return the {@code double} value represented by this object
688: */
689: public double doubleValue() {
690: return (double) value;
691: }
692:
693: /**
694: * Returns a hash code for this {@code Double} object. The
695: * result is the exclusive OR of the two halves of the
696: * {@code long} integer bit representation, exactly as
697: * produced by the method {@link #doubleToLongBits(double)}, of
698: * the primitive {@code double} value represented by this
699: * {@code Double} object. That is, the hash code is the value
700: * of the expression:
701: *
702: * <blockquote>
703: * {@code (int)(v^(v>>>32))}
704: * </blockquote>
705: *
706: * where {@code v} is defined by:
707: *
708: * <blockquote>
709: * {@code long v = Double.doubleToLongBits(this.doubleValue());}
710: * </blockquote>
711: *
712: * @return a {@code hash code} value for this object.
713: */
714: public int hashCode() {
715: long bits = doubleToLongBits(value);
716: return (int) (bits ^ (bits >>> 32));
717: }
718:
719: /**
720: * Compares this object against the specified object. The result
721: * is {@code true} if and only if the argument is not
722: * {@code null} and is a {@code Double} object that
723: * represents a {@code double} that has the same value as the
724: * {@code double} represented by this object. For this
725: * purpose, two {@code double} values are considered to be
726: * the same if and only if the method {@link
727: * #doubleToLongBits(double)} returns the identical
728: * {@code long} value when applied to each.
729: *
730: * <p>Note that in most cases, for two instances of class
731: * {@code Double}, {@code d1} and {@code d2}, the
732: * value of {@code d1.equals(d2)} is {@code true} if and
733: * only if
734: *
735: * <blockquote>
736: * {@code d1.doubleValue() == d2.doubleValue()}
737: * </blockquote>
738: *
739: * <p>also has the value {@code true}. However, there are two
740: * exceptions:
741: * <ul>
742: * <li>If {@code d1} and {@code d2} both represent
743: * {@code Double.NaN}, then the {@code equals} method
744: * returns {@code true}, even though
745: * {@code Double.NaN==Double.NaN} has the value
746: * {@code false}.
747: * <li>If {@code d1} represents {@code +0.0} while
748: * {@code d2} represents {@code -0.0}, or vice versa,
749: * the {@code equal} test has the value {@code false},
750: * even though {@code +0.0==-0.0} has the value {@code true}.
751: * </ul>
752: * This definition allows hash tables to operate properly.
753: * @param obj the object to compare with.
754: * @return {@code true} if the objects are the same;
755: * {@code false} otherwise.
756: * @see java.lang.Double#doubleToLongBits(double)
757: */
758: public boolean equals(Object obj) {
759: return (obj instanceof Double)
760: && (doubleToLongBits(((Double) obj).value) == doubleToLongBits(value));
761: }
762:
763: /**
764: * Returns a representation of the specified floating-point value
765: * according to the IEEE 754 floating-point "double
766: * format" bit layout.
767: *
768: * <p>Bit 63 (the bit that is selected by the mask
769: * {@code 0x8000000000000000L}) represents the sign of the
770: * floating-point number. Bits
771: * 62-52 (the bits that are selected by the mask
772: * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
773: * (the bits that are selected by the mask
774: * {@code 0x000fffffffffffffL}) represent the significand
775: * (sometimes called the mantissa) of the floating-point number.
776: *
777: * <p>If the argument is positive infinity, the result is
778: * {@code 0x7ff0000000000000L}.
779: *
780: * <p>If the argument is negative infinity, the result is
781: * {@code 0xfff0000000000000L}.
782: *
783: * <p>If the argument is NaN, the result is
784: * {@code 0x7ff8000000000000L}.
785: *
786: * <p>In all cases, the result is a {@code long} integer that, when
787: * given to the {@link #longBitsToDouble(long)} method, will produce a
788: * floating-point value the same as the argument to
789: * {@code doubleToLongBits} (except all NaN values are
790: * collapsed to a single "canonical" NaN value).
791: *
792: * @param value a {@code double} precision floating-point number.
793: * @return the bits that represent the floating-point number.
794: */
795: public static long doubleToLongBits(double value) {
796: long result = doubleToRawLongBits(value);
797: // Check for NaN based on values of bit fields, maximum
798: // exponent and nonzero significand.
799: if (((result & DoubleConsts.EXP_BIT_MASK) == DoubleConsts.EXP_BIT_MASK)
800: && (result & DoubleConsts.SIGNIF_BIT_MASK) != 0L)
801: result = 0x7ff8000000000000L;
802: return result;
803: }
804:
805: /**
806: * Returns a representation of the specified floating-point value
807: * according to the IEEE 754 floating-point "double
808: * format" bit layout, preserving Not-a-Number (NaN) values.
809: *
810: * <p>Bit 63 (the bit that is selected by the mask
811: * {@code 0x8000000000000000L}) represents the sign of the
812: * floating-point number. Bits
813: * 62-52 (the bits that are selected by the mask
814: * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
815: * (the bits that are selected by the mask
816: * {@code 0x000fffffffffffffL}) represent the significand
817: * (sometimes called the mantissa) of the floating-point number.
818: *
819: * <p>If the argument is positive infinity, the result is
820: * {@code 0x7ff0000000000000L}.
821: *
822: * <p>If the argument is negative infinity, the result is
823: * {@code 0xfff0000000000000L}.
824: *
825: * <p>If the argument is NaN, the result is the {@code long}
826: * integer representing the actual NaN value. Unlike the
827: * {@code doubleToLongBits} method,
828: * {@code doubleToRawLongBits} does not collapse all the bit
829: * patterns encoding a NaN to a single "canonical" NaN
830: * value.
831: *
832: * <p>In all cases, the result is a {@code long} integer that,
833: * when given to the {@link #longBitsToDouble(long)} method, will
834: * produce a floating-point value the same as the argument to
835: * {@code doubleToRawLongBits}.
836: *
837: * @param value a {@code double} precision floating-point number.
838: * @return the bits that represent the floating-point number.
839: * @since 1.3
840: */
841: public static native long doubleToRawLongBits(double value);
842:
843: /**
844: * Returns the {@code double} value corresponding to a given
845: * bit representation.
846: * The argument is considered to be a representation of a
847: * floating-point value according to the IEEE 754 floating-point
848: * "double format" bit layout.
849: *
850: * <p>If the argument is {@code 0x7ff0000000000000L}, the result
851: * is positive infinity.
852: *
853: * <p>If the argument is {@code 0xfff0000000000000L}, the result
854: * is negative infinity.
855: *
856: * <p>If the argument is any value in the range
857: * {@code 0x7ff0000000000001L} through
858: * {@code 0x7fffffffffffffffL} or in the range
859: * {@code 0xfff0000000000001L} through
860: * {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE
861: * 754 floating-point operation provided by Java can distinguish
862: * between two NaN values of the same type with different bit
863: * patterns. Distinct values of NaN are only distinguishable by
864: * use of the {@code Double.doubleToRawLongBits} method.
865: *
866: * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
867: * values that can be computed from the argument:
868: *
869: * <blockquote><pre>
870: * int s = ((bits >> 63) == 0) ? 1 : -1;
871: * int e = (int)((bits >> 52) & 0x7ffL);
872: * long m = (e == 0) ?
873: * (bits & 0xfffffffffffffL) << 1 :
874: * (bits & 0xfffffffffffffL) | 0x10000000000000L;
875: * </pre></blockquote>
876: *
877: * Then the floating-point result equals the value of the mathematical
878: * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>.
879: *
880: * <p>Note that this method may not be able to return a
881: * {@code double} NaN with exactly same bit pattern as the
882: * {@code long} argument. IEEE 754 distinguishes between two
883: * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
884: * differences between the two kinds of NaN are generally not
885: * visible in Java. Arithmetic operations on signaling NaNs turn
886: * them into quiet NaNs with a different, but often similar, bit
887: * pattern. However, on some processors merely copying a
888: * signaling NaN also performs that conversion. In particular,
889: * copying a signaling NaN to return it to the calling method
890: * may perform this conversion. So {@code longBitsToDouble}
891: * may not be able to return a {@code double} with a
892: * signaling NaN bit pattern. Consequently, for some
893: * {@code long} values,
894: * {@code doubleToRawLongBits(longBitsToDouble(start))} may
895: * <i>not</i> equal {@code start}. Moreover, which
896: * particular bit patterns represent signaling NaNs is platform
897: * dependent; although all NaN bit patterns, quiet or signaling,
898: * must be in the NaN range identified above.
899: *
900: * @param bits any {@code long} integer.
901: * @return the {@code double} floating-point value with the same
902: * bit pattern.
903: */
904: public static native double longBitsToDouble(long bits);
905:
906: /**
907: * Compares two {@code Double} objects numerically. There
908: * are two ways in which comparisons performed by this method
909: * differ from those performed by the Java language numerical
910: * comparison operators ({@code <, <=, ==, >=, >})
911: * when applied to primitive {@code double} values:
912: * <ul><li>
913: * {@code Double.NaN} is considered by this method
914: * to be equal to itself and greater than all other
915: * {@code double} values (including
916: * {@code Double.POSITIVE_INFINITY}).
917: * <li>
918: * {@code 0.0d} is considered by this method to be greater
919: * than {@code -0.0d}.
920: * </ul>
921: * This ensures that the <i>natural ordering</i> of
922: * {@code Double} objects imposed by this method is <i>consistent
923: * with equals</i>.
924: *
925: * @param anotherDouble the {@code Double} to be compared.
926: * @return the value {@code 0} if {@code anotherDouble} is
927: * numerically equal to this {@code Double}; a value
928: * less than {@code 0} if this {@code Double}
929: * is numerically less than {@code anotherDouble};
930: * and a value greater than {@code 0} if this
931: * {@code Double} is numerically greater than
932: * {@code anotherDouble}.
933: *
934: * @since 1.2
935: */
936: public int compareTo(Double anotherDouble) {
937: return Double.compare(value, anotherDouble.value);
938: }
939:
940: /**
941: * Compares the two specified {@code double} values. The sign
942: * of the integer value returned is the same as that of the
943: * integer that would be returned by the call:
944: * <pre>
945: * new Double(d1).compareTo(new Double(d2))
946: * </pre>
947: *
948: * @param d1 the first {@code double} to compare
949: * @param d2 the second {@code double} to compare
950: * @return the value {@code 0} if {@code d1} is
951: * numerically equal to {@code d2}; a value less than
952: * {@code 0} if {@code d1} is numerically less than
953: * {@code d2}; and a value greater than {@code 0}
954: * if {@code d1} is numerically greater than
955: * {@code d2}.
956: * @since 1.4
957: */
958: public static int compare(double d1, double d2) {
959: if (d1 < d2)
960: return -1; // Neither val is NaN, thisVal is smaller
961: if (d1 > d2)
962: return 1; // Neither val is NaN, thisVal is larger
963:
964: long this Bits = Double.doubleToLongBits(d1);
965: long anotherBits = Double.doubleToLongBits(d2);
966:
967: return (this Bits == anotherBits ? 0 : // Values are equal
968: (this Bits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
969: 1)); // (0.0, -0.0) or (NaN, !NaN)
970: }
971:
972: /** use serialVersionUID from JDK 1.0.2 for interoperability */
973: private static final long serialVersionUID = -9172774392245257468L;
974: }
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