1 /*
2 * Copyright 1994-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.lang;
27
28 import sun.misc.FloatingDecimal;
29 import sun.misc.FpUtils;
30 import sun.misc.DoubleConsts;
31
32 /**
33 * The {@code Double} class wraps a value of the primitive type
34 * {@code double} in an object. An object of type
35 * {@code Double} contains a single field whose type is
36 * {@code double}.
37 *
38 * <p>In addition, this class provides several methods for converting a
39 * {@code double} to a {@code String} and a
40 * {@code String} to a {@code double}, as well as other
41 * constants and methods useful when dealing with a
42 * {@code double}.
43 *
44 * @author Lee Boynton
45 * @author Arthur van Hoff
46 * @author Joseph D. Darcy
47 * @since JDK1.0
48 */
49 public final class Double extends Number implements Comparable<Double> {
50 /**
51 * A constant holding the positive infinity of type
52 * {@code double}. It is equal to the value returned by
53 * {@code Double.longBitsToDouble(0x7ff0000000000000L)}.
54 */
55 public static final double POSITIVE_INFINITY = 1.0 / 0.0;
56
57 /**
58 * A constant holding the negative infinity of type
59 * {@code double}. It is equal to the value returned by
60 * {@code Double.longBitsToDouble(0xfff0000000000000L)}.
61 */
62 public static final double NEGATIVE_INFINITY = -1.0 / 0.0;
63
64 /**
65 * A constant holding a Not-a-Number (NaN) value of type
66 * {@code double}. It is equivalent to the value returned by
67 * {@code Double.longBitsToDouble(0x7ff8000000000000L)}.
68 */
69 public static final double NaN = 0.0d / 0.0;
70
71 /**
72 * A constant holding the largest positive finite value of type
73 * {@code double},
74 * (2-2<sup>-52</sup>)·2<sup>1023</sup>. It is equal to
75 * the hexadecimal floating-point literal
76 * {@code 0x1.fffffffffffffP+1023} and also equal to
77 * {@code Double.longBitsToDouble(0x7fefffffffffffffL)}.
78 */
79 public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308
80
81 /**
82 * A constant holding the smallest positive normal value of type
83 * {@code double}, 2<sup>-1022</sup>. It is equal to the
84 * hexadecimal floating-point literal {@code 0x1.0p-1022} and also
85 * equal to {@code Double.longBitsToDouble(0x0010000000000000L)}.
86 *
87 * @since 1.6
88 */
89 public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308
90
91 /**
92 * A constant holding the smallest positive nonzero value of type
93 * {@code double}, 2<sup>-1074</sup>. It is equal to the
94 * hexadecimal floating-point literal
95 * {@code 0x0.0000000000001P-1022} and also equal to
96 * {@code Double.longBitsToDouble(0x1L)}.
97 */
98 public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324
99
100 /**
101 * Maximum exponent a finite {@code double} variable may have.
102 * It is equal to the value returned by
103 * {@code Math.getExponent(Double.MAX_VALUE)}.
104 *
105 * @since 1.6
106 */
107 public static final int MAX_EXPONENT = 1023;
108
109 /**
110 * Minimum exponent a normalized {@code double} variable may
111 * have. It is equal to the value returned by
112 * {@code Math.getExponent(Double.MIN_NORMAL)}.
113 *
114 * @since 1.6
115 */
116 public static final int MIN_EXPONENT = -1022;
117
118 /**
119 * The number of bits used to represent a {@code double} value.
120 *
121 * @since 1.5
122 */
123 public static final int SIZE = 64;
124
125 /**
126 * The {@code Class} instance representing the primitive type
127 * {@code double}.
128 *
129 * @since JDK1.1
130 */
131 public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double");
132
133 /**
134 * Returns a string representation of the {@code double}
135 * argument. All characters mentioned below are ASCII characters.
136 * <ul>
137 * <li>If the argument is NaN, the result is the string
138 * "{@code NaN}".
139 * <li>Otherwise, the result is a string that represents the sign and
140 * magnitude (absolute value) of the argument. If the sign is negative,
141 * the first character of the result is '{@code -}'
142 * (<code>'\u002D'</code>); if the sign is positive, no sign character
143 * appears in the result. As for the magnitude <i>m</i>:
144 * <ul>
145 * <li>If <i>m</i> is infinity, it is represented by the characters
146 * {@code "Infinity"}; thus, positive infinity produces the result
147 * {@code "Infinity"} and negative infinity produces the result
148 * {@code "-Infinity"}.
149 *
150 * <li>If <i>m</i> is zero, it is represented by the characters
151 * {@code "0.0"}; thus, negative zero produces the result
152 * {@code "-0.0"} and positive zero produces the result
153 * {@code "0.0"}.
154 *
155 * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less
156 * than 10<sup>7</sup>, then it is represented as the integer part of
157 * <i>m</i>, in decimal form with no leading zeroes, followed by
158 * '{@code .}' (<code>'\u002E'</code>), followed by one or
159 * more decimal digits representing the fractional part of <i>m</i>.
160 *
161 * <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or
162 * equal to 10<sup>7</sup>, then it is represented in so-called
163 * "computerized scientific notation." Let <i>n</i> be the unique
164 * integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <}
165 * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the
166 * mathematically exact quotient of <i>m</i> and
167 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The
168 * magnitude is then represented as the integer part of <i>a</i>,
169 * as a single decimal digit, followed by '{@code .}'
170 * (<code>'\u002E'</code>), followed by decimal digits
171 * representing the fractional part of <i>a</i>, followed by the
172 * letter '{@code E}' (<code>'\u0045'</code>), followed
173 * by a representation of <i>n</i> as a decimal integer, as
174 * produced by the method {@link Integer#toString(int)}.
175 * </ul>
176 * </ul>
177 * How many digits must be printed for the fractional part of
178 * <i>m</i> or <i>a</i>? There must be at least one digit to represent
179 * the fractional part, and beyond that as many, but only as many, more
180 * digits as are needed to uniquely distinguish the argument value from
181 * adjacent values of type {@code double}. That is, suppose that
182 * <i>x</i> is the exact mathematical value represented by the decimal
183 * representation produced by this method for a finite nonzero argument
184 * <i>d</i>. Then <i>d</i> must be the {@code double} value nearest
185 * to <i>x</i>; or if two {@code double} values are equally close
186 * to <i>x</i>, then <i>d</i> must be one of them and the least
187 * significant bit of the significand of <i>d</i> must be {@code 0}.
188 *
189 * <p>To create localized string representations of a floating-point
190 * value, use subclasses of {@link java.text.NumberFormat}.
191 *
192 * @param d the {@code double} to be converted.
193 * @return a string representation of the argument.
194 */
195 public static String toString(double d) {
196 return new FloatingDecimal(d).toJavaFormatString();
197 }
198
199 /**
200 * Returns a hexadecimal string representation of the
201 * {@code double} argument. All characters mentioned below
202 * are ASCII characters.
203 *
204 * <ul>
205 * <li>If the argument is NaN, the result is the string
206 * "{@code NaN}".
207 * <li>Otherwise, the result is a string that represents the sign
208 * and magnitude of the argument. If the sign is negative, the
209 * first character of the result is '{@code -}'
210 * (<code>'\u002D'</code>); if the sign is positive, no sign
211 * character appears in the result. As for the magnitude <i>m</i>:
212 *
213 * <ul>
214 * <li>If <i>m</i> is infinity, it is represented by the string
215 * {@code "Infinity"}; thus, positive infinity produces the
216 * result {@code "Infinity"} and negative infinity produces
217 * the result {@code "-Infinity"}.
218 *
219 * <li>If <i>m</i> is zero, it is represented by the string
220 * {@code "0x0.0p0"}; thus, negative zero produces the result
221 * {@code "-0x0.0p0"} and positive zero produces the result
222 * {@code "0x0.0p0"}.
223 *
224 * <li>If <i>m</i> is a {@code double} value with a
225 * normalized representation, substrings are used to represent the
226 * significand and exponent fields. The significand is
227 * represented by the characters {@code "0x1."}
228 * followed by a lowercase hexadecimal representation of the rest
229 * of the significand as a fraction. Trailing zeros in the
230 * hexadecimal representation are removed unless all the digits
231 * are zero, in which case a single zero is used. Next, the
232 * exponent is represented by {@code "p"} followed
233 * by a decimal string of the unbiased exponent as if produced by
234 * a call to {@link Integer#toString(int) Integer.toString} on the
235 * exponent value.
236 *
237 * <li>If <i>m</i> is a {@code double} value with a subnormal
238 * representation, the significand is represented by the
239 * characters {@code "0x0."} followed by a
240 * hexadecimal representation of the rest of the significand as a
241 * fraction. Trailing zeros in the hexadecimal representation are
242 * removed. Next, the exponent is represented by
243 * {@code "p-1022"}. Note that there must be at
244 * least one nonzero digit in a subnormal significand.
245 *
246 * </ul>
247 *
248 * </ul>
249 *
250 * <table border>
251 * <caption><h3>Examples</h3></caption>
252 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
253 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
254 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
255 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
256 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
257 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
258 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
259 * <tr><td>{@code Double.MAX_VALUE}</td>
260 * <td>{@code 0x1.fffffffffffffp1023}</td>
261 * <tr><td>{@code Minimum Normal Value}</td>
262 * <td>{@code 0x1.0p-1022}</td>
263 * <tr><td>{@code Maximum Subnormal Value}</td>
264 * <td>{@code 0x0.fffffffffffffp-1022}</td>
265 * <tr><td>{@code Double.MIN_VALUE}</td>
266 * <td>{@code 0x0.0000000000001p-1022}</td>
267 * </table>
268 * @param d the {@code double} to be converted.
269 * @return a hex string representation of the argument.
270 * @since 1.5
271 * @author Joseph D. Darcy
272 */
273 public static String toHexString(double d) {
274 /*
275 * Modeled after the "a" conversion specifier in C99, section
276 * 7.19.6.1; however, the output of this method is more
277 * tightly specified.
278 */
279 if (!FpUtils.isFinite(d) )
280 // For infinity and NaN, use the decimal output.
281 return Double.toString(d);
282 else {
283 // Initialized to maximum size of output.
284 StringBuffer answer = new StringBuffer(24);
285
286 if (FpUtils.rawCopySign(1.0, d) == -1.0) // value is negative,
287 answer.append("-"); // so append sign info
288
289 answer.append("0x");
290
291 d = Math.abs(d);
292
293 if(d == 0.0) {
294 answer.append("0.0p0");
295 }
296 else {
297 boolean subnormal = (d < DoubleConsts.MIN_NORMAL);
298
299 // Isolate significand bits and OR in a high-order bit
300 // so that the string representation has a known
301 // length.
302 long signifBits = (Double.doubleToLongBits(d)
303 & DoubleConsts.SIGNIF_BIT_MASK) |
304 0x1000000000000000L;
305
306 // Subnormal values have a 0 implicit bit; normal
307 // values have a 1 implicit bit.
308 answer.append(subnormal ? "0." : "1.");
309
310 // Isolate the low-order 13 digits of the hex
311 // representation. If all the digits are zero,
312 // replace with a single 0; otherwise, remove all
313 // trailing zeros.
314 String signif = Long.toHexString(signifBits).substring(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" + (subnormal ?
324 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).doubleValue());
493 }
494
495 /**
496 * Returns a {@code Double} instance representing the specified
497 * {@code double} value.
498 * If a new {@code Double} instance is not required, this method
499 * should generally be used in preference to the constructor
500 * {@link #Double(double)}, as this method is likely to yield
501 * significantly better space and time performance by caching
502 * frequently requested values.
503 *
504 * @param d a double value.
505 * @return a {@code Double} instance representing {@code d}.
506 * @since 1.5
507 */
508 public static Double valueOf(double d) {
509 return new Double(d);
510 }
511
512 /**
513 * Returns a new {@code double} initialized to the value
514 * represented by the specified {@code String}, as performed
515 * by the {@code valueOf} method of class
516 * {@code Double}.
517 *
518 * @param s the string to be parsed.
519 * @return the {@code double} value represented by the string
520 * argument.
521 * @throws NumberFormatException if the string does not contain
522 * a parsable {@code double}.
523 * @see java.lang.Double#valueOf(String)
524 * @since 1.2
525 */
526 public static double parseDouble(String s) throws NumberFormatException {
527 return FloatingDecimal.readJavaFormatString(s).doubleValue();
528 }
529
530 /**
531 * Returns {@code true} if the specified number is a
532 * Not-a-Number (NaN) value, {@code false} otherwise.
533 *
534 * @param v the value to be tested.
535 * @return {@code true} if the value of the argument is NaN;
536 * {@code false} otherwise.
537 */
538 static public boolean isNaN(double v) {
539 return (v != v);
540 }
541
542 /**
543 * Returns {@code true} if the specified number is infinitely
544 * large in magnitude, {@code false} otherwise.
545 *
546 * @param v the value to be tested.
547 * @return {@code true} if the value of the argument is positive
548 * infinity or negative infinity; {@code false} otherwise.
549 */
550 static public boolean isInfinite(double v) {
551 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
552 }
553
554 /**
555 * The value of the Double.
556 *
557 * @serial
558 */
559 private final double value;
560
561 /**
562 * Constructs a newly allocated {@code Double} object that
563 * represents the primitive {@code double} argument.
564 *
565 * @param value the value to be represented by the {@code Double}.
566 */
567 public Double(double value) {
568 this.value = value;
569 }
570
571 /**
572 * Constructs a newly allocated {@code Double} object that
573 * represents the floating-point value of type {@code double}
574 * represented by the string. The string is converted to a
575 * {@code double} value as if by the {@code valueOf} method.
576 *
577 * @param s a string to be converted to a {@code Double}.
578 * @throws NumberFormatException if the string does not contain a
579 * parsable number.
580 * @see java.lang.Double#valueOf(java.lang.String)
581 */
582 public Double(String s) throws NumberFormatException {
583 // REMIND: this is inefficient
584 this(valueOf(s).doubleValue());
585 }
586
587 /**
588 * Returns {@code true} if this {@code Double} value is
589 * a Not-a-Number (NaN), {@code false} otherwise.
590 *
591 * @return {@code true} if the value represented by this object is
592 * NaN; {@code false} otherwise.
593 */
594 public boolean isNaN() {
595 return isNaN(value);
596 }
597
598 /**
599 * Returns {@code true} if this {@code Double} value is
600 * infinitely large in magnitude, {@code false} otherwise.
601 *
602 * @return {@code true} if the value represented by this object is
603 * positive infinity or negative infinity;
604 * {@code false} otherwise.
605 */
606 public boolean isInfinite() {
607 return isInfinite(value);
608 }
609
610 /**
611 * Returns a string representation of this {@code Double} object.
612 * The primitive {@code double} value represented by this
613 * object is converted to a string exactly as if by the method
614 * {@code toString} of one argument.
615 *
616 * @return a {@code String} representation of this object.
617 * @see java.lang.Double#toString(double)
618 */
619 public String toString() {
620 return String.valueOf(value);
621 }
622
623 /**
624 * Returns the value of this {@code Double} as a {@code byte} (by
625 * casting to a {@code byte}).
626 *
627 * @return the {@code double} value represented by this object
628 * converted to type {@code byte}
629 * @since JDK1.1
630 */
631 public byte byteValue() {
632 return (byte)value;
633 }
634
635 /**
636 * Returns the value of this {@code Double} as a
637 * {@code short} (by casting to a {@code short}).
638 *
639 * @return the {@code double} value represented by this object
640 * converted to type {@code short}
641 * @since JDK1.1
642 */
643 public short shortValue() {
644 return (short)value;
645 }
646
647 /**
648 * Returns the value of this {@code Double} as an
649 * {@code int} (by casting to type {@code int}).
650 *
651 * @return the {@code double} value represented by this object
652 * converted to type {@code int}
653 */
654 public int intValue() {
655 return (int)value;
656 }
657
658 /**
659 * Returns the value of this {@code Double} as a
660 * {@code long} (by casting to type {@code long}).
661 *
662 * @return the {@code double} value represented by this object
663 * converted to type {@code long}
664 */
665 public long longValue() {
666 return (long)value;
667 }
668
669 /**
670 * Returns the {@code float} value of this
671 * {@code Double} object.
672 *
673 * @return the {@code double} value represented by this object
674 * converted to type {@code float}
675 * @since JDK1.0
676 */
677 public float floatValue() {
678 return (float)value;
679 }
680
681 /**
682 * Returns the {@code double} value of this
683 * {@code Double} object.
684 *
685 * @return the {@code double} value represented by this object
686 */
687 public double doubleValue() {
688 return (double)value;
689 }
690
691 /**
692 * Returns a hash code for this {@code Double} object. The
693 * result is the exclusive OR of the two halves of the
694 * {@code long} integer bit representation, exactly as
695 * produced by the method {@link #doubleToLongBits(double)}, of
696 * the primitive {@code double} value represented by this
697 * {@code Double} object. That is, the hash code is the value
698 * of the expression:
699 *
700 * <blockquote>
701 * {@code (int)(v^(v>>>32))}
702 * </blockquote>
703 *
704 * where {@code v} is defined by:
705 *
706 * <blockquote>
707 * {@code long v = Double.doubleToLongBits(this.doubleValue());}
708 * </blockquote>
709 *
710 * @return a {@code hash code} value for this object.
711 */
712 public int hashCode() {
713 long bits = doubleToLongBits(value);
714 return (int)(bits ^ (bits >>> 32));
715 }
716
717 /**
718 * Compares this object against the specified object. The result
719 * is {@code true} if and only if the argument is not
720 * {@code null} and is a {@code Double} object that
721 * represents a {@code double} that has the same value as the
722 * {@code double} represented by this object. For this
723 * purpose, two {@code double} values are considered to be
724 * the same if and only if the method {@link
725 * #doubleToLongBits(double)} returns the identical
726 * {@code long} value when applied to each.
727 *
728 * <p>Note that in most cases, for two instances of class
729 * {@code Double}, {@code d1} and {@code d2}, the
730 * value of {@code d1.equals(d2)} is {@code true} if and
731 * only if
732 *
733 * <blockquote>
734 * {@code d1.doubleValue() == d2.doubleValue()}
735 * </blockquote>
736 *
737 * <p>also has the value {@code true}. However, there are two
738 * exceptions:
739 * <ul>
740 * <li>If {@code d1} and {@code d2} both represent
741 * {@code Double.NaN}, then the {@code equals} method
742 * returns {@code true}, even though
743 * {@code Double.NaN==Double.NaN} has the value
744 * {@code false}.
745 * <li>If {@code d1} represents {@code +0.0} while
746 * {@code d2} represents {@code -0.0}, or vice versa,
747 * the {@code equal} test has the value {@code false},
748 * even though {@code +0.0==-0.0} has the value {@code true}.
749 * </ul>
750 * This definition allows hash tables to operate properly.
751 * @param obj the object to compare with.
752 * @return {@code true} if the objects are the same;
753 * {@code false} otherwise.
754 * @see java.lang.Double#doubleToLongBits(double)
755 */
756 public boolean equals(Object obj) {
757 return (obj instanceof Double)
758 && (doubleToLongBits(((Double)obj).value) ==
759 doubleToLongBits(value));
760 }
761
762 /**
763 * Returns a representation of the specified floating-point value
764 * according to the IEEE 754 floating-point "double
765 * format" bit layout.
766 *
767 * <p>Bit 63 (the bit that is selected by the mask
768 * {@code 0x8000000000000000L}) represents the sign of the
769 * floating-point number. Bits
770 * 62-52 (the bits that are selected by the mask
771 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
772 * (the bits that are selected by the mask
773 * {@code 0x000fffffffffffffL}) represent the significand
774 * (sometimes called the mantissa) of the floating-point number.
775 *
776 * <p>If the argument is positive infinity, the result is
777 * {@code 0x7ff0000000000000L}.
778 *
779 * <p>If the argument is negative infinity, the result is
780 * {@code 0xfff0000000000000L}.
781 *
782 * <p>If the argument is NaN, the result is
783 * {@code 0x7ff8000000000000L}.
784 *
785 * <p>In all cases, the result is a {@code long} integer that, when
786 * given to the {@link #longBitsToDouble(long)} method, will produce a
787 * floating-point value the same as the argument to
788 * {@code doubleToLongBits} (except all NaN values are
789 * collapsed to a single "canonical" NaN value).
790 *
791 * @param value a {@code double} precision floating-point number.
792 * @return the bits that represent the floating-point number.
793 */
794 public static long doubleToLongBits(double value) {
795 long result = doubleToRawLongBits(value);
796 // Check for NaN based on values of bit fields, maximum
797 // exponent and nonzero significand.
798 if ( ((result & DoubleConsts.EXP_BIT_MASK) ==
799 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 thisBits = Double.doubleToLongBits(d1);
965 long anotherBits = Double.doubleToLongBits(d2);
966
967 return (thisBits == anotherBits ? 0 : // Values are equal
968 (thisBits < 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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