1 /*
2 * Copyright (c) 1994, 2018, 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 java.lang.invoke.MethodHandles;
29 import java.lang.constant.Constable;
30 import java.lang.constant.ConstantDesc;
31 import java.util.Optional;
32
33 import jdk.internal.math.FloatingDecimal;
34 import jdk.internal.math.DoubleConsts;
35 import jdk.internal.math.DoubleToDecimal;
36 import jdk.internal.HotSpotIntrinsicCandidate;
37
38 /**
39 * The {@code Double} class wraps a value of the primitive type
40 * {@code double} in an object. An object of type
41 * {@code Double} contains a single field whose type is
42 * {@code double}.
43 *
44 * <p>In addition, this class provides several methods for converting a
45 * {@code double} to a {@code String} and a
46 * {@code String} to a {@code double}, as well as other
47 * constants and methods useful when dealing with a
48 * {@code double}.
49 *
50 * @author Lee Boynton
51 * @author Arthur van Hoff
52 * @author Joseph D. Darcy
53 * @since 1.0
54 */
55 public final class Double extends Number
56 implements Comparable<Double>, Constable, ConstantDesc {
57 /**
58 * A constant holding the positive infinity of type
59 * {@code double}. It is equal to the value returned by
60 * {@code Double.longBitsToDouble(0x7ff0000000000000L)}.
61 */
62 public static final double POSITIVE_INFINITY = 1.0 / 0.0;
63
64 /**
65 * A constant holding the negative infinity of type
66 * {@code double}. It is equal to the value returned by
67 * {@code Double.longBitsToDouble(0xfff0000000000000L)}.
68 */
69 public static final double NEGATIVE_INFINITY = -1.0 / 0.0;
70
71 /**
72 * A constant holding a Not-a-Number (NaN) value of type
73 * {@code double}. It is equivalent to the value returned by
74 * {@code Double.longBitsToDouble(0x7ff8000000000000L)}.
75 */
76 public static final double NaN = 0.0d / 0.0;
77
78 /**
79 * A constant holding the largest positive finite value of type
80 * {@code double},
81 * (2-2<sup>-52</sup>)·2<sup>1023</sup>. It is equal to
82 * the hexadecimal floating-point literal
83 * {@code 0x1.fffffffffffffP+1023} and also equal to
84 * {@code Double.longBitsToDouble(0x7fefffffffffffffL)}.
85 */
86 public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308
87
88 /**
89 * A constant holding the smallest positive normal value of type
90 * {@code double}, 2<sup>-1022</sup>. It is equal to the
91 * hexadecimal floating-point literal {@code 0x1.0p-1022} and also
92 * equal to {@code Double.longBitsToDouble(0x0010000000000000L)}.
93 *
94 * @since 1.6
95 */
96 public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308
97
98 /**
99 * A constant holding the smallest positive nonzero value of type
100 * {@code double}, 2<sup>-1074</sup>. It is equal to the
101 * hexadecimal floating-point literal
102 * {@code 0x0.0000000000001P-1022} and also equal to
103 * {@code Double.longBitsToDouble(0x1L)}.
104 */
105 public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324
106
107 /**
108 * Maximum exponent a finite {@code double} variable may have.
109 * It is equal to the value returned by
110 * {@code Math.getExponent(Double.MAX_VALUE)}.
111 *
112 * @since 1.6
113 */
114 public static final int MAX_EXPONENT = 1023;
115
116 /**
117 * Minimum exponent a normalized {@code double} variable may
118 * have. It is equal to the value returned by
119 * {@code Math.getExponent(Double.MIN_NORMAL)}.
120 *
121 * @since 1.6
122 */
123 public static final int MIN_EXPONENT = -1022;
124
125 /**
126 * The number of bits used to represent a {@code double} value.
127 *
128 * @since 1.5
129 */
130 public static final int SIZE = 64;
131
132 /**
133 * The number of bytes used to represent a {@code double} value.
134 *
135 * @since 1.8
136 */
137 public static final int BYTES = SIZE / Byte.SIZE;
138
139 /**
140 * The {@code Class} instance representing the primitive type
141 * {@code double}.
142 *
143 * @since 1.1
144 */
145 @SuppressWarnings("unchecked")
146 public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double");
147
148 /**
149 * Returns a string rendering of the {@code double} argument.
150 *
151 * <p>The characters of the result are all drawn from the ASCII set.
152 * <ul>
153 * <li> Any NaN, whether quiet or signaling, is rendered as
154 * {@code "NaN"}, regardless of the sign bit.
155 * <li> The infinities +∞ and -∞ are rendered as
156 * {@code "Infinity"} and {@code "-Infinity"}, respectively.
157 * <li> The positive and negative zeroes are rendered as
158 * {@code "0.0"} and {@code "-0.0"}, respectively.
159 * <li> A finite negative {@code v} is rendered as the sign
160 * '{@code -}' followed by the rendering of the magnitude -{@code v}.
161 * <li> A finite positive {@code v} is rendered in two stages:
162 * <ul>
163 * <li> <em>Selection of a decimal</em>: A well-defined
164 * decimal <i>d</i><sub><code>v</code></sub> is selected
165 * to represent {@code v}.
166 * <li> <em>Formatting as a string</em>: The decimal
167 * <i>d</i><sub><code>v</code></sub> is formatted as a string,
168 * either in plain or in computerized scientific notation,
169 * depending on its value.
170 * </ul>
171 * </ul>
172 *
173 * <p>A <em>decimal</em> is a number of the form
174 * <i>d</i>×10<sup><i>i</i></sup>
175 * for some (unique) integers <i>d</i> > 0 and <i>i</i> such that
176 * <i>d</i> is not a multiple of 10.
177 * These integers are the <em>significand</em> and
178 * the <em>exponent</em>, respectively, of the decimal.
179 * The <em>length</em> of the decimal is the (unique)
180 * integer <i>n</i> meeting
181 * 10<sup><i>n</i>-1</sup> ≤ <i>d</i> < 10<sup><i>n</i></sup>.
182 *
183 * <p>The decimal <i>d</i><sub><code>v</code></sub>
184 * for a finite positive {@code v} is defined as follows:
185 * <ul>
186 * <li>Let <i>R</i> be the set of all decimals that round to {@code v}
187 * according to the usual round-to-closest rule of
188 * IEEE 754 floating-point arithmetic.
189 * <li>Let <i>m</i> be the minimal length over all decimals in <i>R</i>.
190 * <li>When <i>m</i> ≥ 2, let <i>T</i> be the set of all decimals
191 * in <i>R</i> with length <i>m</i>.
192 * Otherwise, let <i>T</i> be the set of all decimals
193 * in <i>R</i> with length 1 or 2.
194 * <li>Define <i>d</i><sub><code>v</code></sub> as
195 * the decimal in <i>T</i> that is closest to {@code v}.
196 * Or if there are two such decimals in <i>T</i>,
197 * select the one with the even significand (there is exactly one).
198 * </ul>
199 *
200 * <p>The (uniquely) selected decimal <i>d</i><sub><code>v</code></sub>
201 * is then formatted.
202 *
203 * <p>Let <i>d</i>, <i>i</i> and <i>n</i> be the significand, exponent and
204 * length of <i>d</i><sub><code>v</code></sub>, respectively.
205 * Further, let <i>e</i> = <i>n</i> + <i>i</i> - 1 and let
206 * <i>d</i><sub>1</sub>…<i>d</i><sub><i>n</i></sub>
207 * be the usual decimal expansion of the significand.
208 * Note that <i>d</i><sub>1</sub> ≠ 0 ≠ <i>d</i><sub><i>n</i></sub>.
209 * <ul>
210 * <li>Case -3 ≤ <i>e</i> < 0:
211 * <i>d</i><sub><code>v</code></sub> is formatted as
212 * <code>0.0</code>…<code>0</code><!--
213 * --><i>d</i><sub>1</sub>…<i>d</i><sub><i>n</i></sub>,
214 * where there are exactly -(<i>n</i> + <i>i</i>) zeroes between
215 * the decimal point and <i>d</i><sub>1</sub>.
216 * For example, 123 × 10<sup>-4</sup> is formatted as
217 * {@code 0.0123}.
218 * <li>Case 0 ≤ <i>e</i> < 7:
219 * <ul>
220 * <li>Subcase <i>i</i> ≥ 0:
221 * <i>d</i><sub><code>v</code></sub> is formatted as
222 * <i>d</i><sub>1</sub>…<i>d</i><sub><i>n</i></sub><!--
223 * --><code>0</code>…<code>0.0</code>,
224 * where there are exactly <i>i</i> zeroes
225 * between <i>d</i><sub><i>n</i></sub> and the decimal point.
226 * For example, 123 × 10<sup>2</sup> is formatted as
227 * {@code 12300.0}.
228 * <li>Subcase <i>i</i> < 0:
229 * <i>d</i><sub><code>v</code></sub> is formatted as
230 * <i>d</i><sub>1</sub>…<!--
231 * --><i>d</i><sub><i>n</i>+<i>i</i></sub>.<!--
232 * --><i>d</i><sub><i>n</i>+<i>i</i>+1</sub>…<!--
233 * --><i>d</i><sub><i>n</i></sub>.
234 * There are exactly -<i>i</i> digits to the right of
235 * the decimal point.
236 * For example, 123 × 10<sup>-1</sup> is formatted as
237 * {@code 12.3}.
238 * </ul>
239 * <li>Case <i>e</i> < -3 or <i>e</i> ≥ 7:
240 * computerized scientific notation is used to format
241 * <i>d</i><sub><code>v</code></sub>.
242 * Here <i>e</i> is formatted as by {@link Integer#toString(int)}.
243 * <ul>
244 * <li>Subcase <i>n</i> = 1:
245 * <i>d</i><sub><code>v</code></sub> is formatted as
246 * <i>d</i><sub>1</sub><code>.0E</code><i>e</i>.
247 * For example, 1 × 10<sup>23</sup> is formatted as
248 * {@code 1.0E23}.
249 * <li>Subcase <i>n</i> > 1:
250 * <i>d</i><sub><code>v</code></sub> is formatted as
251 * <i>d</i><sub>1</sub><code>.</code><i>d</i><sub>2</sub><!--
252 * -->…<i>d</i><sub><i>n</i></sub><code>E</code><i>e</i>.
253 * For example, 123 × 10<sup>-21</sup> is formatted as
254 * {@code 1.23E-19}.
255 * </ul>
256 * </ul>
257 *
258 * @param v the {@code double} to be rendered.
259 * @return a string rendering of the argument.
260 */
261 public static String toString(double v) {
262 return DoubleToDecimal.toString(v);
263 }
264
265 /**
266 * Returns a hexadecimal string representation of the
267 * {@code double} argument. All characters mentioned below
268 * are ASCII characters.
269 *
270 * <ul>
271 * <li>If the argument is NaN, the result is the string
272 * "{@code NaN}".
273 * <li>Otherwise, the result is a string that represents the sign
274 * and magnitude of the argument. If the sign is negative, the
275 * first character of the result is '{@code -}'
276 * ({@code '\u005Cu002D'}); if the sign is positive, no sign
277 * character appears in the result. As for the magnitude <i>m</i>:
278 *
279 * <ul>
280 * <li>If <i>m</i> is infinity, it is represented by the string
281 * {@code "Infinity"}; thus, positive infinity produces the
282 * result {@code "Infinity"} and negative infinity produces
283 * the result {@code "-Infinity"}.
284 *
285 * <li>If <i>m</i> is zero, it is represented by the string
286 * {@code "0x0.0p0"}; thus, negative zero produces the result
287 * {@code "-0x0.0p0"} and positive zero produces the result
288 * {@code "0x0.0p0"}.
289 *
290 * <li>If <i>m</i> is a {@code double} value with a
291 * normalized representation, substrings are used to represent the
292 * significand and exponent fields. The significand is
293 * represented by the characters {@code "0x1."}
294 * followed by a lowercase hexadecimal representation of the rest
295 * of the significand as a fraction. Trailing zeros in the
296 * hexadecimal representation are removed unless all the digits
297 * are zero, in which case a single zero is used. Next, the
298 * exponent is represented by {@code "p"} followed
299 * by a decimal string of the unbiased exponent as if produced by
300 * a call to {@link Integer#toString(int) Integer.toString} on the
301 * exponent value.
302 *
303 * <li>If <i>m</i> is a {@code double} value with a subnormal
304 * representation, the significand is represented by the
305 * characters {@code "0x0."} followed by a
306 * hexadecimal representation of the rest of the significand as a
307 * fraction. Trailing zeros in the hexadecimal representation are
308 * removed. Next, the exponent is represented by
309 * {@code "p-1022"}. Note that there must be at
310 * least one nonzero digit in a subnormal significand.
311 *
312 * </ul>
313 *
314 * </ul>
315 *
316 * <table class="striped">
317 * <caption>Examples</caption>
318 * <thead>
319 * <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th>
320 * </thead>
321 * <tbody style="text-align:right">
322 * <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td>
323 * <tr><th scope="row">{@code -1.0}</th> <td>{@code -0x1.0p0}</td>
324 * <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td>
325 * <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td>
326 * <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td>
327 * <tr><th scope="row">{@code 0.25}</th> <td>{@code 0x1.0p-2}</td>
328 * <tr><th scope="row">{@code Double.MAX_VALUE}</th>
329 * <td>{@code 0x1.fffffffffffffp1023}</td>
330 * <tr><th scope="row">{@code Minimum Normal Value}</th>
331 * <td>{@code 0x1.0p-1022}</td>
332 * <tr><th scope="row">{@code Maximum Subnormal Value}</th>
333 * <td>{@code 0x0.fffffffffffffp-1022}</td>
334 * <tr><th scope="row">{@code Double.MIN_VALUE}</th>
335 * <td>{@code 0x0.0000000000001p-1022}</td>
336 * </tbody>
337 * </table>
338 * @param d the {@code double} to be converted.
339 * @return a hex string representation of the argument.
340 * @since 1.5
341 * @author Joseph D. Darcy
342 */
343 public static String toHexString(double d) {
344 /*
345 * Modeled after the "a" conversion specifier in C99, section
346 * 7.19.6.1; however, the output of this method is more
347 * tightly specified.
348 */
349 if (!isFinite(d) )
350 // For infinity and NaN, use the decimal output.
351 return Double.toString(d);
352 else {
353 // Initialized to maximum size of output.
354 StringBuilder answer = new StringBuilder(24);
355
356 if (Math.copySign(1.0, d) == -1.0) // value is negative,
357 answer.append("-"); // so append sign info
358
359 answer.append("0x");
360
361 d = Math.abs(d);
362
363 if(d == 0.0) {
364 answer.append("0.0p0");
365 } else {
366 boolean subnormal = (d < Double.MIN_NORMAL);
367
368 // Isolate significand bits and OR in a high-order bit
369 // so that the string representation has a known
370 // length.
371 long signifBits = (Double.doubleToLongBits(d)
372 & DoubleConsts.SIGNIF_BIT_MASK) |
373 0x1000000000000000L;
374
375 // Subnormal values have a 0 implicit bit; normal
376 // values have a 1 implicit bit.
377 answer.append(subnormal ? "0." : "1.");
378
379 // Isolate the low-order 13 digits of the hex
380 // representation. If all the digits are zero,
381 // replace with a single 0; otherwise, remove all
382 // trailing zeros.
383 String signif = Long.toHexString(signifBits).substring(3,16);
384 answer.append(signif.equals("0000000000000") ? // 13 zeros
385 "0":
386 signif.replaceFirst("0{1,12}$", ""));
387
388 answer.append('p');
389 // If the value is subnormal, use the E_min exponent
390 // value for double; otherwise, extract and report d's
391 // exponent (the representation of a subnormal uses
392 // E_min -1).
393 answer.append(subnormal ?
394 Double.MIN_EXPONENT:
395 Math.getExponent(d));
396 }
397 return answer.toString();
398 }
399 }
400
401 /**
402 * Returns a {@code Double} object holding the
403 * {@code double} value represented by the argument string
404 * {@code s}.
405 *
406 * <p>If {@code s} is {@code null}, then a
407 * {@code NullPointerException} is thrown.
408 *
409 * <p>Leading and trailing whitespace characters in {@code s}
410 * are ignored. Whitespace is removed as if by the {@link
411 * String#trim} method; that is, both ASCII space and control
412 * characters are removed. The rest of {@code s} should
413 * constitute a <i>FloatValue</i> as described by the lexical
414 * syntax rules:
415 *
416 * <blockquote>
417 * <dl>
418 * <dt><i>FloatValue:</i>
419 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
420 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
421 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
422 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
423 * <dd><i>SignedInteger</i>
424 * </dl>
425 *
426 * <dl>
427 * <dt><i>HexFloatingPointLiteral</i>:
428 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
429 * </dl>
430 *
431 * <dl>
432 * <dt><i>HexSignificand:</i>
433 * <dd><i>HexNumeral</i>
434 * <dd><i>HexNumeral</i> {@code .}
435 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
436 * </i>{@code .}<i> HexDigits</i>
437 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
438 * </i>{@code .} <i>HexDigits</i>
439 * </dl>
440 *
441 * <dl>
442 * <dt><i>BinaryExponent:</i>
443 * <dd><i>BinaryExponentIndicator SignedInteger</i>
444 * </dl>
445 *
446 * <dl>
447 * <dt><i>BinaryExponentIndicator:</i>
448 * <dd>{@code p}
449 * <dd>{@code P}
450 * </dl>
451 *
452 * </blockquote>
453 *
454 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
455 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
456 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
457 * sections of
458 * <cite>The Java™ Language Specification</cite>,
459 * except that underscores are not accepted between digits.
460 * If {@code s} does not have the form of
461 * a <i>FloatValue</i>, then a {@code NumberFormatException}
462 * is thrown. Otherwise, {@code s} is regarded as
463 * representing an exact decimal value in the usual
464 * "computerized scientific notation" or as an exact
465 * hexadecimal value; this exact numerical value is then
466 * conceptually converted to an "infinitely precise"
467 * binary value that is then rounded to type {@code double}
468 * by the usual round-to-nearest rule of IEEE 754 floating-point
469 * arithmetic, which includes preserving the sign of a zero
470 * value.
471 *
472 * Note that the round-to-nearest rule also implies overflow and
473 * underflow behaviour; if the exact value of {@code s} is large
474 * enough in magnitude (greater than or equal to ({@link
475 * #MAX_VALUE} + {@link Math#ulp(double) ulp(MAX_VALUE)}/2),
476 * rounding to {@code double} will result in an infinity and if the
477 * exact value of {@code s} is small enough in magnitude (less
478 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
479 * result in a zero.
480 *
481 * Finally, after rounding a {@code Double} object representing
482 * this {@code double} value is returned.
483 *
484 * <p> To interpret localized string representations of a
485 * floating-point value, use subclasses of {@link
486 * java.text.NumberFormat}.
487 *
488 * <p>Note that trailing format specifiers, specifiers that
489 * determine the type of a floating-point literal
490 * ({@code 1.0f} is a {@code float} value;
491 * {@code 1.0d} is a {@code double} value), do
492 * <em>not</em> influence the results of this method. In other
493 * words, the numerical value of the input string is converted
494 * directly to the target floating-point type. The two-step
495 * sequence of conversions, string to {@code float} followed
496 * by {@code float} to {@code double}, is <em>not</em>
497 * equivalent to converting a string directly to
498 * {@code double}. For example, the {@code float}
499 * literal {@code 0.1f} is equal to the {@code double}
500 * value {@code 0.10000000149011612}; the {@code float}
501 * literal {@code 0.1f} represents a different numerical
502 * value than the {@code double} literal
503 * {@code 0.1}. (The numerical value 0.1 cannot be exactly
504 * represented in a binary floating-point number.)
505 *
506 * <p>To avoid calling this method on an invalid string and having
507 * a {@code NumberFormatException} be thrown, the regular
508 * expression below can be used to screen the input string:
509 *
510 * <pre>{@code
511 * final String Digits = "(\\p{Digit}+)";
512 * final String HexDigits = "(\\p{XDigit}+)";
513 * // an exponent is 'e' or 'E' followed by an optionally
514 * // signed decimal integer.
515 * final String Exp = "[eE][+-]?"+Digits;
516 * final String fpRegex =
517 * ("[\\x00-\\x20]*"+ // Optional leading "whitespace"
518 * "[+-]?(" + // Optional sign character
519 * "NaN|" + // "NaN" string
520 * "Infinity|" + // "Infinity" string
521 *
522 * // A decimal floating-point string representing a finite positive
523 * // number without a leading sign has at most five basic pieces:
524 * // Digits . Digits ExponentPart FloatTypeSuffix
525 * //
526 * // Since this method allows integer-only strings as input
527 * // in addition to strings of floating-point literals, the
528 * // two sub-patterns below are simplifications of the grammar
529 * // productions from section 3.10.2 of
530 * // The Java Language Specification.
531 *
532 * // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
533 * "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
534 *
535 * // . Digits ExponentPart_opt FloatTypeSuffix_opt
536 * "(\\.("+Digits+")("+Exp+")?)|"+
537 *
538 * // Hexadecimal strings
539 * "((" +
540 * // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
541 * "(0[xX]" + HexDigits + "(\\.)?)|" +
542 *
543 * // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
544 * "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
545 *
546 * ")[pP][+-]?" + Digits + "))" +
547 * "[fFdD]?))" +
548 * "[\\x00-\\x20]*");// Optional trailing "whitespace"
549 *
550 * if (Pattern.matches(fpRegex, myString))
551 * Double.valueOf(myString); // Will not throw NumberFormatException
552 * else {
553 * // Perform suitable alternative action
554 * }
555 * }</pre>
556 *
557 * @param s the string to be parsed.
558 * @return a {@code Double} object holding the value
559 * represented by the {@code String} argument.
560 * @throws NumberFormatException if the string does not contain a
561 * parsable number.
562 */
563 public static Double valueOf(String s) throws NumberFormatException {
564 return new Double(parseDouble(s));
565 }
566
567 /**
568 * Returns a {@code Double} instance representing the specified
569 * {@code double} value.
570 * If a new {@code Double} instance is not required, this method
571 * should generally be used in preference to the constructor
572 * {@link #Double(double)}, as this method is likely to yield
573 * significantly better space and time performance by caching
574 * frequently requested values.
575 *
576 * @param d a double value.
577 * @return a {@code Double} instance representing {@code d}.
578 * @since 1.5
579 */
580 @HotSpotIntrinsicCandidate
581 public static Double valueOf(double d) {
582 return new Double(d);
583 }
584
585 /**
586 * Returns a new {@code double} initialized to the value
587 * represented by the specified {@code String}, as performed
588 * by the {@code valueOf} method of class
589 * {@code Double}.
590 *
591 * @param s the string to be parsed.
592 * @return the {@code double} value represented by the string
593 * argument.
594 * @throws NullPointerException if the string is null
595 * @throws NumberFormatException if the string does not contain
596 * a parsable {@code double}.
597 * @see java.lang.Double#valueOf(String)
598 * @since 1.2
599 */
600 public static double parseDouble(String s) throws NumberFormatException {
601 return FloatingDecimal.parseDouble(s);
602 }
603
604 /**
605 * Returns {@code true} if the specified number is a
606 * Not-a-Number (NaN) value, {@code false} otherwise.
607 *
608 * @param v the value to be tested.
609 * @return {@code true} if the value of the argument is NaN;
610 * {@code false} otherwise.
611 */
612 public static boolean isNaN(double v) {
613 return (v != v);
614 }
615
616 /**
617 * Returns {@code true} if the specified number is infinitely
618 * large in magnitude, {@code false} otherwise.
619 *
620 * @param v the value to be tested.
621 * @return {@code true} if the value of the argument is positive
622 * infinity or negative infinity; {@code false} otherwise.
623 */
624 public static boolean isInfinite(double v) {
625 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
626 }
627
628 /**
629 * Returns {@code true} if the argument is a finite floating-point
630 * value; returns {@code false} otherwise (for NaN and infinity
631 * arguments).
632 *
633 * @param d the {@code double} value to be tested
634 * @return {@code true} if the argument is a finite
635 * floating-point value, {@code false} otherwise.
636 * @since 1.8
637 */
638 public static boolean isFinite(double d) {
639 return Math.abs(d) <= Double.MAX_VALUE;
640 }
641
642 /**
643 * The value of the Double.
644 *
645 * @serial
646 */
647 private final double value;
648
649 /**
650 * Constructs a newly allocated {@code Double} object that
651 * represents the primitive {@code double} argument.
652 *
653 * @param value the value to be represented by the {@code Double}.
654 *
655 * @deprecated
656 * It is rarely appropriate to use this constructor. The static factory
657 * {@link #valueOf(double)} is generally a better choice, as it is
658 * likely to yield significantly better space and time performance.
659 */
660 @Deprecated(since="9")
661 public Double(double value) {
662 this.value = value;
663 }
664
665 /**
666 * Constructs a newly allocated {@code Double} object that
667 * represents the floating-point value of type {@code double}
668 * represented by the string. The string is converted to a
669 * {@code double} value as if by the {@code valueOf} method.
670 *
671 * @param s a string to be converted to a {@code Double}.
672 * @throws NumberFormatException if the string does not contain a
673 * parsable number.
674 *
675 * @deprecated
676 * It is rarely appropriate to use this constructor.
677 * Use {@link #parseDouble(String)} to convert a string to a
678 * {@code double} primitive, or use {@link #valueOf(String)}
679 * to convert a string to a {@code Double} object.
680 */
681 @Deprecated(since="9")
682 public Double(String s) throws NumberFormatException {
683 value = parseDouble(s);
684 }
685
686 /**
687 * Returns {@code true} if this {@code Double} value is
688 * a Not-a-Number (NaN), {@code false} otherwise.
689 *
690 * @return {@code true} if the value represented by this object is
691 * NaN; {@code false} otherwise.
692 */
693 public boolean isNaN() {
694 return isNaN(value);
695 }
696
697 /**
698 * Returns {@code true} if this {@code Double} value is
699 * infinitely large in magnitude, {@code false} otherwise.
700 *
701 * @return {@code true} if the value represented by this object is
702 * positive infinity or negative infinity;
703 * {@code false} otherwise.
704 */
705 public boolean isInfinite() {
706 return isInfinite(value);
707 }
708
709 /**
710 * Returns a string representation of this {@code Double} object.
711 * The primitive {@code double} value represented by this
712 * object is converted to a string exactly as if by the method
713 * {@code toString} of one argument.
714 *
715 * @return a {@code String} representation of this object.
716 * @see java.lang.Double#toString(double)
717 */
718 public String toString() {
719 return toString(value);
720 }
721
722 /**
723 * Returns the value of this {@code Double} as a {@code byte}
724 * after a narrowing primitive conversion.
725 *
726 * @return the {@code double} value represented by this object
727 * converted to type {@code byte}
728 * @jls 5.1.3 Narrowing Primitive Conversions
729 * @since 1.1
730 */
731 public byte byteValue() {
732 return (byte)value;
733 }
734
735 /**
736 * Returns the value of this {@code Double} as a {@code short}
737 * after a narrowing primitive conversion.
738 *
739 * @return the {@code double} value represented by this object
740 * converted to type {@code short}
741 * @jls 5.1.3 Narrowing Primitive Conversions
742 * @since 1.1
743 */
744 public short shortValue() {
745 return (short)value;
746 }
747
748 /**
749 * Returns the value of this {@code Double} as an {@code int}
750 * after a narrowing primitive conversion.
751 * @jls 5.1.3 Narrowing Primitive Conversions
752 *
753 * @return the {@code double} value represented by this object
754 * converted to type {@code int}
755 */
756 public int intValue() {
757 return (int)value;
758 }
759
760 /**
761 * Returns the value of this {@code Double} as a {@code long}
762 * after a narrowing primitive conversion.
763 *
764 * @return the {@code double} value represented by this object
765 * converted to type {@code long}
766 * @jls 5.1.3 Narrowing Primitive Conversions
767 */
768 public long longValue() {
769 return (long)value;
770 }
771
772 /**
773 * Returns the value of this {@code Double} as a {@code float}
774 * after a narrowing primitive conversion.
775 *
776 * @return the {@code double} value represented by this object
777 * converted to type {@code float}
778 * @jls 5.1.3 Narrowing Primitive Conversions
779 * @since 1.0
780 */
781 public float floatValue() {
782 return (float)value;
783 }
784
785 /**
786 * Returns the {@code double} value of this {@code Double} object.
787 *
788 * @return the {@code double} value represented by this object
789 */
790 @HotSpotIntrinsicCandidate
791 public double doubleValue() {
792 return value;
793 }
794
795 /**
796 * Returns a hash code for this {@code Double} object. The
797 * result is the exclusive OR of the two halves of the
798 * {@code long} integer bit representation, exactly as
799 * produced by the method {@link #doubleToLongBits(double)}, of
800 * the primitive {@code double} value represented by this
801 * {@code Double} object. That is, the hash code is the value
802 * of the expression:
803 *
804 * <blockquote>
805 * {@code (int)(v^(v>>>32))}
806 * </blockquote>
807 *
808 * where {@code v} is defined by:
809 *
810 * <blockquote>
811 * {@code long v = Double.doubleToLongBits(this.doubleValue());}
812 * </blockquote>
813 *
814 * @return a {@code hash code} value for this object.
815 */
816 @Override
817 public int hashCode() {
818 return Double.hashCode(value);
819 }
820
821 /**
822 * Returns a hash code for a {@code double} value; compatible with
823 * {@code Double.hashCode()}.
824 *
825 * @param value the value to hash
826 * @return a hash code value for a {@code double} value.
827 * @since 1.8
828 */
829 public static int hashCode(double value) {
830 long bits = doubleToLongBits(value);
831 return (int)(bits ^ (bits >>> 32));
832 }
833
834 /**
835 * Compares this object against the specified object. The result
836 * is {@code true} if and only if the argument is not
837 * {@code null} and is a {@code Double} object that
838 * represents a {@code double} that has the same value as the
839 * {@code double} represented by this object. For this
840 * purpose, two {@code double} values are considered to be
841 * the same if and only if the method {@link
842 * #doubleToLongBits(double)} returns the identical
843 * {@code long} value when applied to each.
844 *
845 * <p>Note that in most cases, for two instances of class
846 * {@code Double}, {@code d1} and {@code d2}, the
847 * value of {@code d1.equals(d2)} is {@code true} if and
848 * only if
849 *
850 * <blockquote>
851 * {@code d1.doubleValue() == d2.doubleValue()}
852 * </blockquote>
853 *
854 * <p>also has the value {@code true}. However, there are two
855 * exceptions:
856 * <ul>
857 * <li>If {@code d1} and {@code d2} both represent
858 * {@code Double.NaN}, then the {@code equals} method
859 * returns {@code true}, even though
860 * {@code Double.NaN==Double.NaN} has the value
861 * {@code false}.
862 * <li>If {@code d1} represents {@code +0.0} while
863 * {@code d2} represents {@code -0.0}, or vice versa,
864 * the {@code equal} test has the value {@code false},
865 * even though {@code +0.0==-0.0} has the value {@code true}.
866 * </ul>
867 * This definition allows hash tables to operate properly.
868 * @param obj the object to compare with.
869 * @return {@code true} if the objects are the same;
870 * {@code false} otherwise.
871 * @see java.lang.Double#doubleToLongBits(double)
872 */
873 public boolean equals(Object obj) {
874 return (obj instanceof Double)
875 && (doubleToLongBits(((Double)obj).value) ==
876 doubleToLongBits(value));
877 }
878
879 /**
880 * Returns a representation of the specified floating-point value
881 * according to the IEEE 754 floating-point "double
882 * format" bit layout.
883 *
884 * <p>Bit 63 (the bit that is selected by the mask
885 * {@code 0x8000000000000000L}) represents the sign of the
886 * floating-point number. Bits
887 * 62-52 (the bits that are selected by the mask
888 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
889 * (the bits that are selected by the mask
890 * {@code 0x000fffffffffffffL}) represent the significand
891 * (sometimes called the mantissa) of the floating-point number.
892 *
893 * <p>If the argument is positive infinity, the result is
894 * {@code 0x7ff0000000000000L}.
895 *
896 * <p>If the argument is negative infinity, the result is
897 * {@code 0xfff0000000000000L}.
898 *
899 * <p>If the argument is NaN, the result is
900 * {@code 0x7ff8000000000000L}.
901 *
902 * <p>In all cases, the result is a {@code long} integer that, when
903 * given to the {@link #longBitsToDouble(long)} method, will produce a
904 * floating-point value the same as the argument to
905 * {@code doubleToLongBits} (except all NaN values are
906 * collapsed to a single "canonical" NaN value).
907 *
908 * @param value a {@code double} precision floating-point number.
909 * @return the bits that represent the floating-point number.
910 */
911 @HotSpotIntrinsicCandidate
912 public static long doubleToLongBits(double value) {
913 if (!isNaN(value)) {
914 return doubleToRawLongBits(value);
915 }
916 return 0x7ff8000000000000L;
917 }
918
919 /**
920 * Returns a representation of the specified floating-point value
921 * according to the IEEE 754 floating-point "double
922 * format" bit layout, preserving Not-a-Number (NaN) values.
923 *
924 * <p>Bit 63 (the bit that is selected by the mask
925 * {@code 0x8000000000000000L}) represents the sign of the
926 * floating-point number. Bits
927 * 62-52 (the bits that are selected by the mask
928 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
929 * (the bits that are selected by the mask
930 * {@code 0x000fffffffffffffL}) represent the significand
931 * (sometimes called the mantissa) of the floating-point number.
932 *
933 * <p>If the argument is positive infinity, the result is
934 * {@code 0x7ff0000000000000L}.
935 *
936 * <p>If the argument is negative infinity, the result is
937 * {@code 0xfff0000000000000L}.
938 *
939 * <p>If the argument is NaN, the result is the {@code long}
940 * integer representing the actual NaN value. Unlike the
941 * {@code doubleToLongBits} method,
942 * {@code doubleToRawLongBits} does not collapse all the bit
943 * patterns encoding a NaN to a single "canonical" NaN
944 * value.
945 *
946 * <p>In all cases, the result is a {@code long} integer that,
947 * when given to the {@link #longBitsToDouble(long)} method, will
948 * produce a floating-point value the same as the argument to
949 * {@code doubleToRawLongBits}.
950 *
951 * @param value a {@code double} precision floating-point number.
952 * @return the bits that represent the floating-point number.
953 * @since 1.3
954 */
955 @HotSpotIntrinsicCandidate
956 public static native long doubleToRawLongBits(double value);
957
958 /**
959 * Returns the {@code double} value corresponding to a given
960 * bit representation.
961 * The argument is considered to be a representation of a
962 * floating-point value according to the IEEE 754 floating-point
963 * "double format" bit layout.
964 *
965 * <p>If the argument is {@code 0x7ff0000000000000L}, the result
966 * is positive infinity.
967 *
968 * <p>If the argument is {@code 0xfff0000000000000L}, the result
969 * is negative infinity.
970 *
971 * <p>If the argument is any value in the range
972 * {@code 0x7ff0000000000001L} through
973 * {@code 0x7fffffffffffffffL} or in the range
974 * {@code 0xfff0000000000001L} through
975 * {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE
976 * 754 floating-point operation provided by Java can distinguish
977 * between two NaN values of the same type with different bit
978 * patterns. Distinct values of NaN are only distinguishable by
979 * use of the {@code Double.doubleToRawLongBits} method.
980 *
981 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
982 * values that can be computed from the argument:
983 *
984 * <blockquote><pre>{@code
985 * int s = ((bits >> 63) == 0) ? 1 : -1;
986 * int e = (int)((bits >> 52) & 0x7ffL);
987 * long m = (e == 0) ?
988 * (bits & 0xfffffffffffffL) << 1 :
989 * (bits & 0xfffffffffffffL) | 0x10000000000000L;
990 * }</pre></blockquote>
991 *
992 * Then the floating-point result equals the value of the mathematical
993 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>.
994 *
995 * <p>Note that this method may not be able to return a
996 * {@code double} NaN with exactly same bit pattern as the
997 * {@code long} argument. IEEE 754 distinguishes between two
998 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
999 * differences between the two kinds of NaN are generally not
1000 * visible in Java. Arithmetic operations on signaling NaNs turn
1001 * them into quiet NaNs with a different, but often similar, bit
1002 * pattern. However, on some processors merely copying a
1003 * signaling NaN also performs that conversion. In particular,
1004 * copying a signaling NaN to return it to the calling method
1005 * may perform this conversion. So {@code longBitsToDouble}
1006 * may not be able to return a {@code double} with a
1007 * signaling NaN bit pattern. Consequently, for some
1008 * {@code long} values,
1009 * {@code doubleToRawLongBits(longBitsToDouble(start))} may
1010 * <i>not</i> equal {@code start}. Moreover, which
1011 * particular bit patterns represent signaling NaNs is platform
1012 * dependent; although all NaN bit patterns, quiet or signaling,
1013 * must be in the NaN range identified above.
1014 *
1015 * @param bits any {@code long} integer.
1016 * @return the {@code double} floating-point value with the same
1017 * bit pattern.
1018 */
1019 @HotSpotIntrinsicCandidate
1020 public static native double longBitsToDouble(long bits);
1021
1022 /**
1023 * Compares two {@code Double} objects numerically. There
1024 * are two ways in which comparisons performed by this method
1025 * differ from those performed by the Java language numerical
1026 * comparison operators ({@code <, <=, ==, >=, >})
1027 * when applied to primitive {@code double} values:
1028 * <ul><li>
1029 * {@code Double.NaN} is considered by this method
1030 * to be equal to itself and greater than all other
1031 * {@code double} values (including
1032 * {@code Double.POSITIVE_INFINITY}).
1033 * <li>
1034 * {@code 0.0d} is considered by this method to be greater
1035 * than {@code -0.0d}.
1036 * </ul>
1037 * This ensures that the <i>natural ordering</i> of
1038 * {@code Double} objects imposed by this method is <i>consistent
1039 * with equals</i>.
1040 *
1041 * @param anotherDouble the {@code Double} to be compared.
1042 * @return the value {@code 0} if {@code anotherDouble} is
1043 * numerically equal to this {@code Double}; a value
1044 * less than {@code 0} if this {@code Double}
1045 * is numerically less than {@code anotherDouble};
1046 * and a value greater than {@code 0} if this
1047 * {@code Double} is numerically greater than
1048 * {@code anotherDouble}.
1049 *
1050 * @since 1.2
1051 */
1052 public int compareTo(Double anotherDouble) {
1053 return Double.compare(value, anotherDouble.value);
1054 }
1055
1056 /**
1057 * Compares the two specified {@code double} values. The sign
1058 * of the integer value returned is the same as that of the
1059 * integer that would be returned by the call:
1060 * <pre>
1061 * new Double(d1).compareTo(new Double(d2))
1062 * </pre>
1063 *
1064 * @param d1 the first {@code double} to compare
1065 * @param d2 the second {@code double} to compare
1066 * @return the value {@code 0} if {@code d1} is
1067 * numerically equal to {@code d2}; a value less than
1068 * {@code 0} if {@code d1} is numerically less than
1069 * {@code d2}; and a value greater than {@code 0}
1070 * if {@code d1} is numerically greater than
1071 * {@code d2}.
1072 * @since 1.4
1073 */
1074 public static int compare(double d1, double d2) {
1075 if (d1 < d2)
1076 return -1; // Neither val is NaN, thisVal is smaller
1077 if (d1 > d2)
1078 return 1; // Neither val is NaN, thisVal is larger
1079
1080 // Cannot use doubleToRawLongBits because of possibility of NaNs.
1081 long thisBits = Double.doubleToLongBits(d1);
1082 long anotherBits = Double.doubleToLongBits(d2);
1083
1084 return (thisBits == anotherBits ? 0 : // Values are equal
1085 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1086 1)); // (0.0, -0.0) or (NaN, !NaN)
1087 }
1088
1089 /**
1090 * Adds two {@code double} values together as per the + operator.
1091 *
1092 * @param a the first operand
1093 * @param b the second operand
1094 * @return the sum of {@code a} and {@code b}
1095 * @jls 4.2.4 Floating-Point Operations
1096 * @see java.util.function.BinaryOperator
1097 * @since 1.8
1098 */
1099 public static double sum(double a, double b) {
1100 return a + b;
1101 }
1102
1103 /**
1104 * Returns the greater of two {@code double} values
1105 * as if by calling {@link Math#max(double, double) Math.max}.
1106 *
1107 * @param a the first operand
1108 * @param b the second operand
1109 * @return the greater of {@code a} and {@code b}
1110 * @see java.util.function.BinaryOperator
1111 * @since 1.8
1112 */
1113 public static double max(double a, double b) {
1114 return Math.max(a, b);
1115 }
1116
1117 /**
1118 * Returns the smaller of two {@code double} values
1119 * as if by calling {@link Math#min(double, double) Math.min}.
1120 *
1121 * @param a the first operand
1122 * @param b the second operand
1123 * @return the smaller of {@code a} and {@code b}.
1124 * @see java.util.function.BinaryOperator
1125 * @since 1.8
1126 */
1127 public static double min(double a, double b) {
1128 return Math.min(a, b);
1129 }
1130
1131 /**
1132 * Returns an {@link Optional} containing the nominal descriptor for this
1133 * instance, which is the instance itself.
1134 *
1135 * @return an {@link Optional} describing the {@linkplain Double} instance
1136 * @since 12
1137 */
1138 @Override
1139 public Optional<Double> describeConstable() {
1140 return Optional.of(this);
1141 }
1142
1143 /**
1144 * Resolves this instance as a {@link ConstantDesc}, the result of which is
1145 * the instance itself.
1146 *
1147 * @param lookup ignored
1148 * @return the {@linkplain Double} instance
1149 * @since 12
1150 */
1151 @Override
1152 public Double resolveConstantDesc(MethodHandles.Lookup lookup) {
1153 return this;
1154 }
1155
1156 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1157 private static final long serialVersionUID = -9172774392245257468L;
1158 }