1 /*
2 * Copyright (c) 1994, 2011, Oracle and/or its affiliates. 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * 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 number of bytes used to represent a {@code double} value.
127 *
128 * @since 1.8
129 */
130 public static final int BYTES = SIZE / Byte.SIZE;
131
132 /**
133 * The {@code Class} instance representing the primitive type
134 * {@code double}.
135 *
136 * @since JDK1.1
137 */
138 public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double");
139
140 /**
141 * Returns a string representation of the {@code double}
142 * argument. All characters mentioned below are ASCII characters.
143 * <ul>
144 * <li>If the argument is NaN, the result is the string
145 * "{@code NaN}".
146 * <li>Otherwise, the result is a string that represents the sign and
147 * magnitude (absolute value) of the argument. If the sign is negative,
148 * the first character of the result is '{@code -}'
149 * (<code>'\u002D'</code>); if the sign is positive, no sign character
150 * appears in the result. As for the magnitude <i>m</i>:
151 * <ul>
152 * <li>If <i>m</i> is infinity, it is represented by the characters
153 * {@code "Infinity"}; thus, positive infinity produces the result
154 * {@code "Infinity"} and negative infinity produces the result
155 * {@code "-Infinity"}.
156 *
157 * <li>If <i>m</i> is zero, it is represented by the characters
158 * {@code "0.0"}; thus, negative zero produces the result
159 * {@code "-0.0"} and positive zero produces the result
160 * {@code "0.0"}.
161 *
162 * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less
163 * than 10<sup>7</sup>, then it is represented as the integer part of
164 * <i>m</i>, in decimal form with no leading zeroes, followed by
165 * '{@code .}' (<code>'\u002E'</code>), followed by one or
166 * more decimal digits representing the fractional part of <i>m</i>.
167 *
168 * <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or
169 * equal to 10<sup>7</sup>, then it is represented in so-called
170 * "computerized scientific notation." Let <i>n</i> be the unique
171 * integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <}
172 * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the
173 * mathematically exact quotient of <i>m</i> and
174 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The
175 * magnitude is then represented as the integer part of <i>a</i>,
176 * as a single decimal digit, followed by '{@code .}'
177 * (<code>'\u002E'</code>), followed by decimal digits
178 * representing the fractional part of <i>a</i>, followed by the
179 * letter '{@code E}' (<code>'\u0045'</code>), followed
180 * by a representation of <i>n</i> as a decimal integer, as
181 * produced by the method {@link Integer#toString(int)}.
182 * </ul>
183 * </ul>
184 * How many digits must be printed for the fractional part of
185 * <i>m</i> or <i>a</i>? There must be at least one digit to represent
186 * the fractional part, and beyond that as many, but only as many, more
187 * digits as are needed to uniquely distinguish the argument value from
188 * adjacent values of type {@code double}. That is, suppose that
189 * <i>x</i> is the exact mathematical value represented by the decimal
190 * representation produced by this method for a finite nonzero argument
191 * <i>d</i>. Then <i>d</i> must be the {@code double} value nearest
192 * to <i>x</i>; or if two {@code double} values are equally close
193 * to <i>x</i>, then <i>d</i> must be one of them and the least
194 * significant bit of the significand of <i>d</i> must be {@code 0}.
195 *
196 * <p>To create localized string representations of a floating-point
197 * value, use subclasses of {@link java.text.NumberFormat}.
198 *
199 * @param d the {@code double} to be converted.
200 * @return a string representation of the argument.
201 */
202 public static String toString(double d) {
203 return new FloatingDecimal(d).toJavaFormatString();
204 }
205
206 /**
207 * Returns a hexadecimal string representation of the
208 * {@code double} argument. All characters mentioned below
209 * are ASCII characters.
210 *
211 * <ul>
212 * <li>If the argument is NaN, the result is the string
213 * "{@code NaN}".
214 * <li>Otherwise, the result is a string that represents the sign
215 * and magnitude of the argument. If the sign is negative, the
216 * first character of the result is '{@code -}'
217 * (<code>'\u002D'</code>); if the sign is positive, no sign
218 * character appears in the result. As for the magnitude <i>m</i>:
219 *
220 * <ul>
221 * <li>If <i>m</i> is infinity, it is represented by the string
222 * {@code "Infinity"}; thus, positive infinity produces the
223 * result {@code "Infinity"} and negative infinity produces
224 * the result {@code "-Infinity"}.
225 *
226 * <li>If <i>m</i> is zero, it is represented by the string
227 * {@code "0x0.0p0"}; thus, negative zero produces the result
228 * {@code "-0x0.0p0"} and positive zero produces the result
229 * {@code "0x0.0p0"}.
230 *
231 * <li>If <i>m</i> is a {@code double} value with a
232 * normalized representation, substrings are used to represent the
233 * significand and exponent fields. The significand is
234 * represented by the characters {@code "0x1."}
235 * followed by a lowercase hexadecimal representation of the rest
236 * of the significand as a fraction. Trailing zeros in the
237 * hexadecimal representation are removed unless all the digits
238 * are zero, in which case a single zero is used. Next, the
239 * exponent is represented by {@code "p"} followed
240 * by a decimal string of the unbiased exponent as if produced by
241 * a call to {@link Integer#toString(int) Integer.toString} on the
242 * exponent value.
243 *
244 * <li>If <i>m</i> is a {@code double} value with a subnormal
245 * representation, the significand is represented by the
246 * characters {@code "0x0."} followed by a
247 * hexadecimal representation of the rest of the significand as a
248 * fraction. Trailing zeros in the hexadecimal representation are
249 * removed. Next, the exponent is represented by
250 * {@code "p-1022"}. Note that there must be at
251 * least one nonzero digit in a subnormal significand.
252 *
253 * </ul>
254 *
255 * </ul>
256 *
257 * <table border>
258 * <caption><h3>Examples</h3></caption>
259 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
260 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
261 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
262 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
263 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
264 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
265 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
266 * <tr><td>{@code Double.MAX_VALUE}</td>
267 * <td>{@code 0x1.fffffffffffffp1023}</td>
268 * <tr><td>{@code Minimum Normal Value}</td>
269 * <td>{@code 0x1.0p-1022}</td>
270 * <tr><td>{@code Maximum Subnormal Value}</td>
271 * <td>{@code 0x0.fffffffffffffp-1022}</td>
272 * <tr><td>{@code Double.MIN_VALUE}</td>
273 * <td>{@code 0x0.0000000000001p-1022}</td>
274 * </table>
275 * @param d the {@code double} to be converted.
276 * @return a hex string representation of the argument.
277 * @since 1.5
278 * @author Joseph D. Darcy
279 */
280 public static String toHexString(double d) {
281 /*
282 * Modeled after the "a" conversion specifier in C99, section
283 * 7.19.6.1; however, the output of this method is more
284 * tightly specified.
285 */
286 if (!FpUtils.isFinite(d) )
287 // For infinity and NaN, use the decimal output.
288 return Double.toString(d);
289 else {
290 // Initialized to maximum size of output.
291 StringBuffer answer = new StringBuffer(24);
292
293 if (Math.copySign(1.0, d) == -1.0) // value is negative,
294 answer.append("-"); // so append sign info
295
296 answer.append("0x");
297
298 d = Math.abs(d);
299
300 if(d == 0.0) {
301 answer.append("0.0p0");
302 }
303 else {
304 boolean subnormal = (d < DoubleConsts.MIN_NORMAL);
305
306 // Isolate significand bits and OR in a high-order bit
307 // so that the string representation has a known
308 // length.
309 long signifBits = (Double.doubleToLongBits(d)
310 & DoubleConsts.SIGNIF_BIT_MASK) |
311 0x1000000000000000L;
312
313 // Subnormal values have a 0 implicit bit; normal
314 // values have a 1 implicit bit.
315 answer.append(subnormal ? "0." : "1.");
316
317 // Isolate the low-order 13 digits of the hex
318 // representation. If all the digits are zero,
319 // replace with a single 0; otherwise, remove all
320 // trailing zeros.
321 String signif = Long.toHexString(signifBits).substring(3,16);
322 answer.append(signif.equals("0000000000000") ? // 13 zeros
323 "0":
324 signif.replaceFirst("0{1,12}$", ""));
325
326 // If the value is subnormal, use the E_min exponent
327 // value for double; otherwise, extract and report d's
328 // exponent (the representation of a subnormal uses
329 // E_min -1).
330 answer.append("p" + (subnormal ?
331 DoubleConsts.MIN_EXPONENT:
332 Math.getExponent(d) ));
333 }
334 return answer.toString();
335 }
336 }
337
338 /**
339 * Returns a {@code Double} object holding the
340 * {@code double} value represented by the argument string
341 * {@code s}.
342 *
343 * <p>If {@code s} is {@code null}, then a
344 * {@code NullPointerException} is thrown.
345 *
346 * <p>Leading and trailing whitespace characters in {@code s}
347 * are ignored. Whitespace is removed as if by the {@link
348 * String#trim} method; that is, both ASCII space and control
349 * characters are removed. The rest of {@code s} should
350 * constitute a <i>FloatValue</i> as described by the lexical
351 * syntax rules:
352 *
353 * <blockquote>
354 * <dl>
355 * <dt><i>FloatValue:</i>
356 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
357 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
358 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
359 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
360 * <dd><i>SignedInteger</i>
361 * </dl>
362 *
363 * <p>
364 *
365 * <dl>
366 * <dt><i>HexFloatingPointLiteral</i>:
367 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
368 * </dl>
369 *
370 * <p>
371 *
372 * <dl>
373 * <dt><i>HexSignificand:</i>
374 * <dd><i>HexNumeral</i>
375 * <dd><i>HexNumeral</i> {@code .}
376 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
377 * </i>{@code .}<i> HexDigits</i>
378 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
379 * </i>{@code .} <i>HexDigits</i>
380 * </dl>
381 *
382 * <p>
383 *
384 * <dl>
385 * <dt><i>BinaryExponent:</i>
386 * <dd><i>BinaryExponentIndicator SignedInteger</i>
387 * </dl>
388 *
389 * <p>
390 *
391 * <dl>
392 * <dt><i>BinaryExponentIndicator:</i>
393 * <dd>{@code p}
394 * <dd>{@code P}
395 * </dl>
396 *
397 * </blockquote>
398 *
399 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
400 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
401 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
402 * sections of
403 * <cite>The Java™ Language Specification</cite>,
404 * except that underscores are not accepted between digits.
405 * If {@code s} does not have the form of
406 * a <i>FloatValue</i>, then a {@code NumberFormatException}
407 * is thrown. Otherwise, {@code s} is regarded as
408 * representing an exact decimal value in the usual
409 * "computerized scientific notation" or as an exact
410 * hexadecimal value; this exact numerical value is then
411 * conceptually converted to an "infinitely precise"
412 * binary value that is then rounded to type {@code double}
413 * by the usual round-to-nearest rule of IEEE 754 floating-point
414 * arithmetic, which includes preserving the sign of a zero
415 * value.
416 *
417 * Note that the round-to-nearest rule also implies overflow and
418 * underflow behaviour; if the exact value of {@code s} is large
419 * enough in magnitude (greater than or equal to ({@link
420 * #MAX_VALUE} + {@link Math#ulp(double) ulp(MAX_VALUE)}/2),
421 * rounding to {@code double} will result in an infinity and if the
422 * exact value of {@code s} is small enough in magnitude (less
423 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
424 * result in a zero.
425 *
426 * Finally, after rounding a {@code Double} object representing
427 * this {@code double} value is returned.
428 *
429 * <p> To interpret localized string representations of a
430 * floating-point value, use subclasses of {@link
431 * java.text.NumberFormat}.
432 *
433 * <p>Note that trailing format specifiers, specifiers that
434 * determine the type of a floating-point literal
435 * ({@code 1.0f} is a {@code float} value;
436 * {@code 1.0d} is a {@code double} value), do
437 * <em>not</em> influence the results of this method. In other
438 * words, the numerical value of the input string is converted
439 * directly to the target floating-point type. The two-step
440 * sequence of conversions, string to {@code float} followed
441 * by {@code float} to {@code double}, is <em>not</em>
442 * equivalent to converting a string directly to
443 * {@code double}. For example, the {@code float}
444 * literal {@code 0.1f} is equal to the {@code double}
445 * value {@code 0.10000000149011612}; the {@code float}
446 * literal {@code 0.1f} represents a different numerical
447 * value than the {@code double} literal
448 * {@code 0.1}. (The numerical value 0.1 cannot be exactly
449 * represented in a binary floating-point number.)
450 *
451 * <p>To avoid calling this method on an invalid string and having
452 * a {@code NumberFormatException} be thrown, the regular
453 * expression below can be used to screen the input string:
454 *
455 * <code>
456 * <pre>
457 * final String Digits = "(\\p{Digit}+)";
458 * final String HexDigits = "(\\p{XDigit}+)";
459 * // an exponent is 'e' or 'E' followed by an optionally
460 * // signed decimal integer.
461 * final String Exp = "[eE][+-]?"+Digits;
462 * final String fpRegex =
463 * ("[\\x00-\\x20]*"+ // Optional leading "whitespace"
464 * "[+-]?(" + // Optional sign character
465 * "NaN|" + // "NaN" string
466 * "Infinity|" + // "Infinity" string
467 *
468 * // A decimal floating-point string representing a finite positive
469 * // number without a leading sign has at most five basic pieces:
470 * // Digits . Digits ExponentPart FloatTypeSuffix
471 * //
472 * // Since this method allows integer-only strings as input
473 * // in addition to strings of floating-point literals, the
474 * // two sub-patterns below are simplifications of the grammar
475 * // productions from section 3.10.2 of
476 * // <cite>The Java™ Language Specification</cite>.
477 *
478 * // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
479 * "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
480 *
481 * // . Digits ExponentPart_opt FloatTypeSuffix_opt
482 * "(\\.("+Digits+")("+Exp+")?)|"+
483 *
484 * // Hexadecimal strings
485 * "((" +
486 * // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
487 * "(0[xX]" + HexDigits + "(\\.)?)|" +
488 *
489 * // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
490 * "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
491 *
492 * ")[pP][+-]?" + Digits + "))" +
493 * "[fFdD]?))" +
494 * "[\\x00-\\x20]*");// Optional trailing "whitespace"
495 *
496 * if (Pattern.matches(fpRegex, myString))
497 * Double.valueOf(myString); // Will not throw NumberFormatException
498 * else {
499 * // Perform suitable alternative action
500 * }
501 * </pre>
502 * </code>
503 *
504 * @param s the string to be parsed.
505 * @return a {@code Double} object holding the value
506 * represented by the {@code String} argument.
507 * @throws NumberFormatException if the string does not contain a
508 * parsable number.
509 */
510 public static Double valueOf(String s) throws NumberFormatException {
511 return new Double(FloatingDecimal.readJavaFormatString(s).doubleValue());
512 }
513
514 /**
515 * Returns a {@code Double} instance representing the specified
516 * {@code double} value.
517 * If a new {@code Double} instance is not required, this method
518 * should generally be used in preference to the constructor
519 * {@link #Double(double)}, as this method is likely to yield
520 * significantly better space and time performance by caching
521 * frequently requested values.
522 *
523 * @param d a double value.
524 * @return a {@code Double} instance representing {@code d}.
525 * @since 1.5
526 */
527 public static Double valueOf(double d) {
528 return new Double(d);
529 }
530
531 /**
532 * Returns a new {@code double} initialized to the value
533 * represented by the specified {@code String}, as performed
534 * by the {@code valueOf} method of class
535 * {@code Double}.
536 *
537 * @param s the string to be parsed.
538 * @return the {@code double} value represented by the string
539 * argument.
540 * @throws NullPointerException if the string is null
541 * @throws NumberFormatException if the string does not contain
542 * a parsable {@code double}.
543 * @see java.lang.Double#valueOf(String)
544 * @since 1.2
545 */
546 public static double parseDouble(String s) throws NumberFormatException {
547 return FloatingDecimal.readJavaFormatString(s).doubleValue();
548 }
549
550 /**
551 * Returns {@code true} if the specified number is a
552 * Not-a-Number (NaN) value, {@code false} otherwise.
553 *
554 * @param v the value to be tested.
555 * @return {@code true} if the value of the argument is NaN;
556 * {@code false} otherwise.
557 */
558 static public boolean isNaN(double v) {
559 return (v != v);
560 }
561
562 /**
563 * Returns {@code true} if the specified number is infinitely
564 * large in magnitude, {@code false} otherwise.
565 *
566 * @param v the value to be tested.
567 * @return {@code true} if the value of the argument is positive
568 * infinity or negative infinity; {@code false} otherwise.
569 */
570 static public boolean isInfinite(double v) {
571 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
572 }
573
574 /**
575 * The value of the Double.
576 *
577 * @serial
578 */
579 private final double value;
580
581 /**
582 * Constructs a newly allocated {@code Double} object that
583 * represents the primitive {@code double} argument.
584 *
585 * @param value the value to be represented by the {@code Double}.
586 */
587 public Double(double value) {
588 this.value = value;
589 }
590
591 /**
592 * Constructs a newly allocated {@code Double} object that
593 * represents the floating-point value of type {@code double}
594 * represented by the string. The string is converted to a
595 * {@code double} value as if by the {@code valueOf} method.
596 *
597 * @param s a string to be converted to a {@code Double}.
598 * @throws NumberFormatException if the string does not contain a
599 * parsable number.
600 * @see java.lang.Double#valueOf(java.lang.String)
601 */
602 public Double(String s) throws NumberFormatException {
603 // REMIND: this is inefficient
604 this(valueOf(s).doubleValue());
605 }
606
607 /**
608 * Returns {@code true} if this {@code Double} value is
609 * a Not-a-Number (NaN), {@code false} otherwise.
610 *
611 * @return {@code true} if the value represented by this object is
612 * NaN; {@code false} otherwise.
613 */
614 public boolean isNaN() {
615 return isNaN(value);
616 }
617
618 /**
619 * Returns {@code true} if this {@code Double} value is
620 * infinitely large in magnitude, {@code false} otherwise.
621 *
622 * @return {@code true} if the value represented by this object is
623 * positive infinity or negative infinity;
624 * {@code false} otherwise.
625 */
626 public boolean isInfinite() {
627 return isInfinite(value);
628 }
629
630 /**
631 * Returns a string representation of this {@code Double} object.
632 * The primitive {@code double} value represented by this
633 * object is converted to a string exactly as if by the method
634 * {@code toString} of one argument.
635 *
636 * @return a {@code String} representation of this object.
637 * @see java.lang.Double#toString(double)
638 */
639 public String toString() {
640 return toString(value);
641 }
642
643 /**
644 * Returns the value of this {@code Double} as a {@code byte}
645 * after a narrowing primitive conversion.
646 *
647 * @return the {@code double} value represented by this object
648 * converted to type {@code byte}
649 * @jls 5.1.3 Narrowing Primitive Conversions
650 * @since JDK1.1
651 */
652 public byte byteValue() {
653 return (byte)value;
654 }
655
656 /**
657 * Returns the value of this {@code Double} as a {@code short}
658 * after a narrowing primitive conversion.
659 *
660 * @return the {@code double} value represented by this object
661 * converted to type {@code short}
662 * @jls 5.1.3 Narrowing Primitive Conversions
663 * @since JDK1.1
664 */
665 public short shortValue() {
666 return (short)value;
667 }
668
669 /**
670 * Returns the value of this {@code Double} as an {@code int}
671 * after a narrowing primitive conversion.
672 * @jls 5.1.3 Narrowing Primitive Conversions
673 *
674 * @return the {@code double} value represented by this object
675 * converted to type {@code int}
676 */
677 public int intValue() {
678 return (int)value;
679 }
680
681 /**
682 * Returns the value of this {@code Double} as a {@code long}
683 * after a narrowing primitive conversion.
684 *
685 * @return the {@code double} value represented by this object
686 * converted to type {@code long}
687 * @jls 5.1.3 Narrowing Primitive Conversions
688 */
689 public long longValue() {
690 return (long)value;
691 }
692
693 /**
694 * Returns the value of this {@code Double} as a {@code float}
695 * after a narrowing primitive conversion.
696 *
697 * @return the {@code double} value represented by this object
698 * converted to type {@code float}
699 * @jls 5.1.3 Narrowing Primitive Conversions
700 * @since JDK1.0
701 */
702 public float floatValue() {
703 return (float)value;
704 }
705
706 /**
707 * Returns the {@code double} value of this {@code Double} object.
708 *
709 * @return the {@code double} value represented by this object
710 */
711 public double doubleValue() {
712 return (double)value;
713 }
714
715 /**
716 * Returns a hash code for this {@code Double} object. The
717 * result is the exclusive OR of the two halves of the
718 * {@code long} integer bit representation, exactly as
719 * produced by the method {@link #doubleToLongBits(double)}, of
720 * the primitive {@code double} value represented by this
721 * {@code Double} object. That is, the hash code is the value
722 * of the expression:
723 *
724 * <blockquote>
725 * {@code (int)(v^(v>>>32))}
726 * </blockquote>
727 *
728 * where {@code v} is defined by:
729 *
730 * <blockquote>
731 * {@code long v = Double.doubleToLongBits(this.doubleValue());}
732 * </blockquote>
733 *
734 * @return a {@code hash code} value for this object.
735 */
736 public int hashCode() {
737 long bits = doubleToLongBits(value);
738 return (int)(bits ^ (bits >>> 32));
739 }
740
741 /**
742 * Returns a hash code for a {@code double} value; compatible with
743 * {@code Double.hashCode()}.
744 *
745 * @since 1.8
746 *
747 * @return a hash code value for a {@code double} value.
748 */
749 public static int hashCode(double value) {
750 long bits = doubleToLongBits(value);
751 return (int)(bits ^ (bits >>> 32));
752 }
753
754 /**
755 * Compares this object against the specified object. The result
756 * is {@code true} if and only if the argument is not
757 * {@code null} and is a {@code Double} object that
758 * represents a {@code double} that has the same value as the
759 * {@code double} represented by this object. For this
760 * purpose, two {@code double} values are considered to be
761 * the same if and only if the method {@link
762 * #doubleToLongBits(double)} returns the identical
763 * {@code long} value when applied to each.
764 *
765 * <p>Note that in most cases, for two instances of class
766 * {@code Double}, {@code d1} and {@code d2}, the
767 * value of {@code d1.equals(d2)} is {@code true} if and
768 * only if
769 *
770 * <blockquote>
771 * {@code d1.doubleValue() == d2.doubleValue()}
772 * </blockquote>
773 *
774 * <p>also has the value {@code true}. However, there are two
775 * exceptions:
776 * <ul>
777 * <li>If {@code d1} and {@code d2} both represent
778 * {@code Double.NaN}, then the {@code equals} method
779 * returns {@code true}, even though
780 * {@code Double.NaN==Double.NaN} has the value
781 * {@code false}.
782 * <li>If {@code d1} represents {@code +0.0} while
783 * {@code d2} represents {@code -0.0}, or vice versa,
784 * the {@code equal} test has the value {@code false},
785 * even though {@code +0.0==-0.0} has the value {@code true}.
786 * </ul>
787 * This definition allows hash tables to operate properly.
788 * @param obj the object to compare with.
789 * @return {@code true} if the objects are the same;
790 * {@code false} otherwise.
791 * @see java.lang.Double#doubleToLongBits(double)
792 */
793 public boolean equals(Object obj) {
794 return (obj instanceof Double)
795 && (doubleToLongBits(((Double)obj).value) ==
796 doubleToLongBits(value));
797 }
798
799 /**
800 * Returns a representation of the specified floating-point value
801 * according to the IEEE 754 floating-point "double
802 * format" bit layout.
803 *
804 * <p>Bit 63 (the bit that is selected by the mask
805 * {@code 0x8000000000000000L}) represents the sign of the
806 * floating-point number. Bits
807 * 62-52 (the bits that are selected by the mask
808 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
809 * (the bits that are selected by the mask
810 * {@code 0x000fffffffffffffL}) represent the significand
811 * (sometimes called the mantissa) of the floating-point number.
812 *
813 * <p>If the argument is positive infinity, the result is
814 * {@code 0x7ff0000000000000L}.
815 *
816 * <p>If the argument is negative infinity, the result is
817 * {@code 0xfff0000000000000L}.
818 *
819 * <p>If the argument is NaN, the result is
820 * {@code 0x7ff8000000000000L}.
821 *
822 * <p>In all cases, the result is a {@code long} integer that, when
823 * given to the {@link #longBitsToDouble(long)} method, will produce a
824 * floating-point value the same as the argument to
825 * {@code doubleToLongBits} (except all NaN values are
826 * collapsed to a single "canonical" NaN value).
827 *
828 * @param value a {@code double} precision floating-point number.
829 * @return the bits that represent the floating-point number.
830 */
831 public static long doubleToLongBits(double value) {
832 long result = doubleToRawLongBits(value);
833 // Check for NaN based on values of bit fields, maximum
834 // exponent and nonzero significand.
835 if ( ((result & DoubleConsts.EXP_BIT_MASK) ==
836 DoubleConsts.EXP_BIT_MASK) &&
837 (result & DoubleConsts.SIGNIF_BIT_MASK) != 0L)
838 result = 0x7ff8000000000000L;
839 return result;
840 }
841
842 /**
843 * Returns a representation of the specified floating-point value
844 * according to the IEEE 754 floating-point "double
845 * format" bit layout, preserving Not-a-Number (NaN) values.
846 *
847 * <p>Bit 63 (the bit that is selected by the mask
848 * {@code 0x8000000000000000L}) represents the sign of the
849 * floating-point number. Bits
850 * 62-52 (the bits that are selected by the mask
851 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
852 * (the bits that are selected by the mask
853 * {@code 0x000fffffffffffffL}) represent the significand
854 * (sometimes called the mantissa) of the floating-point number.
855 *
856 * <p>If the argument is positive infinity, the result is
857 * {@code 0x7ff0000000000000L}.
858 *
859 * <p>If the argument is negative infinity, the result is
860 * {@code 0xfff0000000000000L}.
861 *
862 * <p>If the argument is NaN, the result is the {@code long}
863 * integer representing the actual NaN value. Unlike the
864 * {@code doubleToLongBits} method,
865 * {@code doubleToRawLongBits} does not collapse all the bit
866 * patterns encoding a NaN to a single "canonical" NaN
867 * value.
868 *
869 * <p>In all cases, the result is a {@code long} integer that,
870 * when given to the {@link #longBitsToDouble(long)} method, will
871 * produce a floating-point value the same as the argument to
872 * {@code doubleToRawLongBits}.
873 *
874 * @param value a {@code double} precision floating-point number.
875 * @return the bits that represent the floating-point number.
876 * @since 1.3
877 */
878 public static native long doubleToRawLongBits(double value);
879
880 /**
881 * Returns the {@code double} value corresponding to a given
882 * bit representation.
883 * The argument is considered to be a representation of a
884 * floating-point value according to the IEEE 754 floating-point
885 * "double format" bit layout.
886 *
887 * <p>If the argument is {@code 0x7ff0000000000000L}, the result
888 * is positive infinity.
889 *
890 * <p>If the argument is {@code 0xfff0000000000000L}, the result
891 * is negative infinity.
892 *
893 * <p>If the argument is any value in the range
894 * {@code 0x7ff0000000000001L} through
895 * {@code 0x7fffffffffffffffL} or in the range
896 * {@code 0xfff0000000000001L} through
897 * {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE
898 * 754 floating-point operation provided by Java can distinguish
899 * between two NaN values of the same type with different bit
900 * patterns. Distinct values of NaN are only distinguishable by
901 * use of the {@code Double.doubleToRawLongBits} method.
902 *
903 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
904 * values that can be computed from the argument:
905 *
906 * <blockquote><pre>
907 * int s = ((bits >> 63) == 0) ? 1 : -1;
908 * int e = (int)((bits >> 52) & 0x7ffL);
909 * long m = (e == 0) ?
910 * (bits & 0xfffffffffffffL) << 1 :
911 * (bits & 0xfffffffffffffL) | 0x10000000000000L;
912 * </pre></blockquote>
913 *
914 * Then the floating-point result equals the value of the mathematical
915 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>.
916 *
917 * <p>Note that this method may not be able to return a
918 * {@code double} NaN with exactly same bit pattern as the
919 * {@code long} argument. IEEE 754 distinguishes between two
920 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
921 * differences between the two kinds of NaN are generally not
922 * visible in Java. Arithmetic operations on signaling NaNs turn
923 * them into quiet NaNs with a different, but often similar, bit
924 * pattern. However, on some processors merely copying a
925 * signaling NaN also performs that conversion. In particular,
926 * copying a signaling NaN to return it to the calling method
927 * may perform this conversion. So {@code longBitsToDouble}
928 * may not be able to return a {@code double} with a
929 * signaling NaN bit pattern. Consequently, for some
930 * {@code long} values,
931 * {@code doubleToRawLongBits(longBitsToDouble(start))} may
932 * <i>not</i> equal {@code start}. Moreover, which
933 * particular bit patterns represent signaling NaNs is platform
934 * dependent; although all NaN bit patterns, quiet or signaling,
935 * must be in the NaN range identified above.
936 *
937 * @param bits any {@code long} integer.
938 * @return the {@code double} floating-point value with the same
939 * bit pattern.
940 */
941 public static native double longBitsToDouble(long bits);
942
943 /**
944 * Compares two {@code Double} objects numerically. There
945 * are two ways in which comparisons performed by this method
946 * differ from those performed by the Java language numerical
947 * comparison operators ({@code <, <=, ==, >=, >})
948 * when applied to primitive {@code double} values:
949 * <ul><li>
950 * {@code Double.NaN} is considered by this method
951 * to be equal to itself and greater than all other
952 * {@code double} values (including
953 * {@code Double.POSITIVE_INFINITY}).
954 * <li>
955 * {@code 0.0d} is considered by this method to be greater
956 * than {@code -0.0d}.
957 * </ul>
958 * This ensures that the <i>natural ordering</i> of
959 * {@code Double} objects imposed by this method is <i>consistent
960 * with equals</i>.
961 *
962 * @param anotherDouble the {@code Double} to be compared.
963 * @return the value {@code 0} if {@code anotherDouble} is
964 * numerically equal to this {@code Double}; a value
965 * less than {@code 0} if this {@code Double}
966 * is numerically less than {@code anotherDouble};
967 * and a value greater than {@code 0} if this
968 * {@code Double} is numerically greater than
969 * {@code anotherDouble}.
970 *
971 * @since 1.2
972 */
973 public int compareTo(Double anotherDouble) {
974 return Double.compare(value, anotherDouble.value);
975 }
976
977 /**
978 * Compares the two specified {@code double} values. The sign
979 * of the integer value returned is the same as that of the
980 * integer that would be returned by the call:
981 * <pre>
982 * new Double(d1).compareTo(new Double(d2))
983 * </pre>
984 *
985 * @param d1 the first {@code double} to compare
986 * @param d2 the second {@code double} to compare
987 * @return the value {@code 0} if {@code d1} is
988 * numerically equal to {@code d2}; a value less than
989 * {@code 0} if {@code d1} is numerically less than
990 * {@code d2}; and a value greater than {@code 0}
991 * if {@code d1} is numerically greater than
992 * {@code d2}.
993 * @since 1.4
994 */
995 public static int compare(double d1, double d2) {
996 if (d1 < d2)
997 return -1; // Neither val is NaN, thisVal is smaller
998 if (d1 > d2)
999 return 1; // Neither val is NaN, thisVal is larger
1000
1001 // Cannot use doubleToRawLongBits because of possibility of NaNs.
1002 long thisBits = Double.doubleToLongBits(d1);
1003 long anotherBits = Double.doubleToLongBits(d2);
1004
1005 return (thisBits == anotherBits ? 0 : // Values are equal
1006 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1007 1)); // (0.0, -0.0) or (NaN, !NaN)
1008 }
1009
1010 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1011 private static final long serialVersionUID = -9172774392245257468L;
1012 }