1 /*
2 * Copyright (c) 1994, 2012, 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 @SuppressWarnings("unchecked")
139 public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double");
140
141 /**
142 * Returns a string representation of the {@code double}
143 * argument. All characters mentioned below are ASCII characters.
144 * <ul>
145 * <li>If the argument is NaN, the result is the string
146 * "{@code NaN}".
147 * <li>Otherwise, the result is a string that represents the sign and
148 * magnitude (absolute value) of the argument. If the sign is negative,
149 * the first character of the result is '{@code -}'
150 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
151 * appears in the result. As for the magnitude <i>m</i>:
152 * <ul>
153 * <li>If <i>m</i> is infinity, it is represented by the characters
154 * {@code "Infinity"}; thus, positive infinity produces the result
155 * {@code "Infinity"} and negative infinity produces the result
156 * {@code "-Infinity"}.
157 *
158 * <li>If <i>m</i> is zero, it is represented by the characters
159 * {@code "0.0"}; thus, negative zero produces the result
160 * {@code "-0.0"} and positive zero produces the result
161 * {@code "0.0"}.
162 *
163 * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less
164 * than 10<sup>7</sup>, then it is represented as the integer part of
165 * <i>m</i>, in decimal form with no leading zeroes, followed by
166 * '{@code .}' ({@code '\u005Cu002E'}), followed by one or
167 * more decimal digits representing the fractional part of <i>m</i>.
168 *
169 * <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or
170 * equal to 10<sup>7</sup>, then it is represented in so-called
171 * "computerized scientific notation." Let <i>n</i> be the unique
172 * integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <}
173 * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the
174 * mathematically exact quotient of <i>m</i> and
175 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The
176 * magnitude is then represented as the integer part of <i>a</i>,
177 * as a single decimal digit, followed by '{@code .}'
178 * ({@code '\u005Cu002E'}), followed by decimal digits
179 * representing the fractional part of <i>a</i>, followed by the
180 * letter '{@code E}' ({@code '\u005Cu0045'}), followed
181 * by a representation of <i>n</i> as a decimal integer, as
182 * produced by the method {@link Integer#toString(int)}.
183 * </ul>
184 * </ul>
185 * How many digits must be printed for the fractional part of
186 * <i>m</i> or <i>a</i>? There must be at least one digit to represent
187 * the fractional part, and beyond that as many, but only as many, more
188 * digits as are needed to uniquely distinguish the argument value from
189 * adjacent values of type {@code double}. That is, suppose that
190 * <i>x</i> is the exact mathematical value represented by the decimal
191 * representation produced by this method for a finite nonzero argument
192 * <i>d</i>. Then <i>d</i> must be the {@code double} value nearest
193 * to <i>x</i>; or if two {@code double} values are equally close
194 * to <i>x</i>, then <i>d</i> must be one of them and the least
195 * significant bit of the significand of <i>d</i> must be {@code 0}.
196 *
197 * <p>To create localized string representations of a floating-point
198 * value, use subclasses of {@link java.text.NumberFormat}.
199 *
200 * @param d the {@code double} to be converted.
201 * @return a string representation of the argument.
202 */
203 public static String toString(double d) {
204 return new FloatingDecimal(d).toJavaFormatString();
205 }
206
207 /**
208 * Returns a hexadecimal string representation of the
209 * {@code double} argument. All characters mentioned below
210 * are ASCII characters.
211 *
212 * <ul>
213 * <li>If the argument is NaN, the result is the string
214 * "{@code NaN}".
215 * <li>Otherwise, the result is a string that represents the sign
216 * and magnitude of the argument. If the sign is negative, the
217 * first character of the result is '{@code -}'
218 * ({@code '\u005Cu002D'}); if the sign is positive, no sign
219 * character appears in the result. As for the magnitude <i>m</i>:
220 *
221 * <ul>
222 * <li>If <i>m</i> is infinity, it is represented by the string
223 * {@code "Infinity"}; thus, positive infinity produces the
224 * result {@code "Infinity"} and negative infinity produces
225 * the result {@code "-Infinity"}.
226 *
227 * <li>If <i>m</i> is zero, it is represented by the string
228 * {@code "0x0.0p0"}; thus, negative zero produces the result
229 * {@code "-0x0.0p0"} and positive zero produces the result
230 * {@code "0x0.0p0"}.
231 *
232 * <li>If <i>m</i> is a {@code double} value with a
233 * normalized representation, substrings are used to represent the
234 * significand and exponent fields. The significand is
235 * represented by the characters {@code "0x1."}
236 * followed by a lowercase hexadecimal representation of the rest
237 * of the significand as a fraction. Trailing zeros in the
238 * hexadecimal representation are removed unless all the digits
239 * are zero, in which case a single zero is used. Next, the
240 * exponent is represented by {@code "p"} followed
241 * by a decimal string of the unbiased exponent as if produced by
242 * a call to {@link Integer#toString(int) Integer.toString} on the
243 * exponent value.
244 *
245 * <li>If <i>m</i> is a {@code double} value with a subnormal
246 * representation, the significand is represented by the
247 * characters {@code "0x0."} followed by a
248 * hexadecimal representation of the rest of the significand as a
249 * fraction. Trailing zeros in the hexadecimal representation are
250 * removed. Next, the exponent is represented by
251 * {@code "p-1022"}. Note that there must be at
252 * least one nonzero digit in a subnormal significand.
253 *
254 * </ul>
255 *
256 * </ul>
257 *
258 * <table border>
259 * <caption><h3>Examples</h3></caption>
260 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
261 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
262 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
263 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
264 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
265 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
266 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
267 * <tr><td>{@code Double.MAX_VALUE}</td>
268 * <td>{@code 0x1.fffffffffffffp1023}</td>
269 * <tr><td>{@code Minimum Normal Value}</td>
270 * <td>{@code 0x1.0p-1022}</td>
271 * <tr><td>{@code Maximum Subnormal Value}</td>
272 * <td>{@code 0x0.fffffffffffffp-1022}</td>
273 * <tr><td>{@code Double.MIN_VALUE}</td>
274 * <td>{@code 0x0.0000000000001p-1022}</td>
275 * </table>
276 * @param d the {@code double} to be converted.
277 * @return a hex string representation of the argument.
278 * @since 1.5
279 * @author Joseph D. Darcy
280 */
281 public static String toHexString(double d) {
282 /*
283 * Modeled after the "a" conversion specifier in C99, section
284 * 7.19.6.1; however, the output of this method is more
285 * tightly specified.
286 */
287 if (!isFinite(d) )
288 // For infinity and NaN, use the decimal output.
289 return Double.toString(d);
290 else {
291 // Initialized to maximum size of output.
292 StringBuffer answer = new StringBuffer(24);
293
294 if (Math.copySign(1.0, d) == -1.0) // value is negative,
295 answer.append("-"); // so append sign info
296
297 answer.append("0x");
298
299 d = Math.abs(d);
300
301 if(d == 0.0) {
302 answer.append("0.0p0");
303 }
304 else {
305 boolean subnormal = (d < DoubleConsts.MIN_NORMAL);
306
307 // Isolate significand bits and OR in a high-order bit
308 // so that the string representation has a known
309 // length.
310 long signifBits = (Double.doubleToLongBits(d)
311 & DoubleConsts.SIGNIF_BIT_MASK) |
312 0x1000000000000000L;
313
314 // Subnormal values have a 0 implicit bit; normal
315 // values have a 1 implicit bit.
316 answer.append(subnormal ? "0." : "1.");
317
318 // Isolate the low-order 13 digits of the hex
319 // representation. If all the digits are zero,
320 // replace with a single 0; otherwise, remove all
321 // trailing zeros.
322 String signif = Long.toHexString(signifBits).substring(3,16);
323 answer.append(signif.equals("0000000000000") ? // 13 zeros
324 "0":
325 signif.replaceFirst("0{1,12}$", ""));
326
327 // If the value is subnormal, use the E_min exponent
328 // value for double; otherwise, extract and report d's
329 // exponent (the representation of a subnormal uses
330 // E_min -1).
331 answer.append("p" + (subnormal ?
332 DoubleConsts.MIN_EXPONENT:
333 Math.getExponent(d) ));
334 }
335 return answer.toString();
336 }
337 }
338
339 /**
340 * Returns a {@code Double} object holding the
341 * {@code double} value represented by the argument string
342 * {@code s}.
343 *
344 * <p>If {@code s} is {@code null}, then a
345 * {@code NullPointerException} is thrown.
346 *
347 * <p>Leading and trailing whitespace characters in {@code s}
348 * are ignored. Whitespace is removed as if by the {@link
349 * String#trim} method; that is, both ASCII space and control
350 * characters are removed. The rest of {@code s} should
351 * constitute a <i>FloatValue</i> as described by the lexical
352 * syntax rules:
353 *
354 * <blockquote>
355 * <dl>
356 * <dt><i>FloatValue:</i>
357 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
358 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
359 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
360 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
361 * <dd><i>SignedInteger</i>
362 * </dl>
363 *
364 * <p>
365 *
366 * <dl>
367 * <dt><i>HexFloatingPointLiteral</i>:
368 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
369 * </dl>
370 *
371 * <p>
372 *
373 * <dl>
374 * <dt><i>HexSignificand:</i>
375 * <dd><i>HexNumeral</i>
376 * <dd><i>HexNumeral</i> {@code .}
377 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
378 * </i>{@code .}<i> HexDigits</i>
379 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
380 * </i>{@code .} <i>HexDigits</i>
381 * </dl>
382 *
383 * <p>
384 *
385 * <dl>
386 * <dt><i>BinaryExponent:</i>
387 * <dd><i>BinaryExponentIndicator SignedInteger</i>
388 * </dl>
389 *
390 * <p>
391 *
392 * <dl>
393 * <dt><i>BinaryExponentIndicator:</i>
394 * <dd>{@code p}
395 * <dd>{@code P}
396 * </dl>
397 *
398 * </blockquote>
399 *
400 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
401 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
402 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
403 * sections of
404 * <cite>The Java™ Language Specification</cite>,
405 * except that underscores are not accepted between digits.
406 * If {@code s} does not have the form of
407 * a <i>FloatValue</i>, then a {@code NumberFormatException}
408 * is thrown. Otherwise, {@code s} is regarded as
409 * representing an exact decimal value in the usual
410 * "computerized scientific notation" or as an exact
411 * hexadecimal value; this exact numerical value is then
412 * conceptually converted to an "infinitely precise"
413 * binary value that is then rounded to type {@code double}
414 * by the usual round-to-nearest rule of IEEE 754 floating-point
415 * arithmetic, which includes preserving the sign of a zero
416 * value.
417 *
418 * Note that the round-to-nearest rule also implies overflow and
419 * underflow behaviour; if the exact value of {@code s} is large
420 * enough in magnitude (greater than or equal to ({@link
421 * #MAX_VALUE} + {@link Math#ulp(double) ulp(MAX_VALUE)}/2),
422 * rounding to {@code double} will result in an infinity and if the
423 * exact value of {@code s} is small enough in magnitude (less
424 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
425 * result in a zero.
426 *
427 * Finally, after rounding a {@code Double} object representing
428 * this {@code double} value is returned.
429 *
430 * <p> To interpret localized string representations of a
431 * floating-point value, use subclasses of {@link
432 * java.text.NumberFormat}.
433 *
434 * <p>Note that trailing format specifiers, specifiers that
435 * determine the type of a floating-point literal
436 * ({@code 1.0f} is a {@code float} value;
437 * {@code 1.0d} is a {@code double} value), do
438 * <em>not</em> influence the results of this method. In other
439 * words, the numerical value of the input string is converted
440 * directly to the target floating-point type. The two-step
441 * sequence of conversions, string to {@code float} followed
442 * by {@code float} to {@code double}, is <em>not</em>
443 * equivalent to converting a string directly to
444 * {@code double}. For example, the {@code float}
445 * literal {@code 0.1f} is equal to the {@code double}
446 * value {@code 0.10000000149011612}; the {@code float}
447 * literal {@code 0.1f} represents a different numerical
448 * value than the {@code double} literal
449 * {@code 0.1}. (The numerical value 0.1 cannot be exactly
450 * represented in a binary floating-point number.)
451 *
452 * <p>To avoid calling this method on an invalid string and having
453 * a {@code NumberFormatException} be thrown, the regular
454 * expression below can be used to screen the input string:
455 *
456 * <code>
457 * <pre>
458 * final String Digits = "(\\p{Digit}+)";
459 * final String HexDigits = "(\\p{XDigit}+)";
460 * // an exponent is 'e' or 'E' followed by an optionally
461 * // signed decimal integer.
462 * final String Exp = "[eE][+-]?"+Digits;
463 * final String fpRegex =
464 * ("[\\x00-\\x20]*"+ // Optional leading "whitespace"
465 * "[+-]?(" + // Optional sign character
466 * "NaN|" + // "NaN" string
467 * "Infinity|" + // "Infinity" string
468 *
469 * // A decimal floating-point string representing a finite positive
470 * // number without a leading sign has at most five basic pieces:
471 * // Digits . Digits ExponentPart FloatTypeSuffix
472 * //
473 * // Since this method allows integer-only strings as input
474 * // in addition to strings of floating-point literals, the
475 * // two sub-patterns below are simplifications of the grammar
476 * // productions from section 3.10.2 of
477 * // <cite>The Java™ Language Specification</cite>.
478 *
479 * // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
480 * "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
481 *
482 * // . Digits ExponentPart_opt FloatTypeSuffix_opt
483 * "(\\.("+Digits+")("+Exp+")?)|"+
484 *
485 * // Hexadecimal strings
486 * "((" +
487 * // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
488 * "(0[xX]" + HexDigits + "(\\.)?)|" +
489 *
490 * // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
491 * "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
492 *
493 * ")[pP][+-]?" + Digits + "))" +
494 * "[fFdD]?))" +
495 * "[\\x00-\\x20]*");// Optional trailing "whitespace"
496 *
497 * if (Pattern.matches(fpRegex, myString))
498 * Double.valueOf(myString); // Will not throw NumberFormatException
499 * else {
500 * // Perform suitable alternative action
501 * }
502 * </pre>
503 * </code>
504 *
505 * @param s the string to be parsed.
506 * @return a {@code Double} object holding the value
507 * represented by the {@code String} argument.
508 * @throws NumberFormatException if the string does not contain a
509 * parsable number.
510 */
511 public static Double valueOf(String s) throws NumberFormatException {
512 return new Double(FloatingDecimal.readJavaFormatString(s).doubleValue());
513 }
514
515 /**
516 * Returns a {@code Double} instance representing the specified
517 * {@code double} value.
518 * If a new {@code Double} instance is not required, this method
519 * should generally be used in preference to the constructor
520 * {@link #Double(double)}, as this method is likely to yield
521 * significantly better space and time performance by caching
522 * frequently requested values.
523 *
524 * @param d a double value.
525 * @return a {@code Double} instance representing {@code d}.
526 * @since 1.5
527 */
528 public static Double valueOf(double d) {
529 return new Double(d);
530 }
531
532 /**
533 * Returns a new {@code double} initialized to the value
534 * represented by the specified {@code String}, as performed
535 * by the {@code valueOf} method of class
536 * {@code Double}.
537 *
538 * @param s the string to be parsed.
539 * @return the {@code double} value represented by the string
540 * argument.
541 * @throws NullPointerException if the string is null
542 * @throws NumberFormatException if the string does not contain
543 * a parsable {@code double}.
544 * @see java.lang.Double#valueOf(String)
545 * @since 1.2
546 */
547 public static double parseDouble(String s) throws NumberFormatException {
548 return FloatingDecimal.readJavaFormatString(s).doubleValue();
549 }
550
551 /**
552 * Returns {@code true} if the specified number is a
553 * Not-a-Number (NaN) value, {@code false} otherwise.
554 *
555 * @param v the value to be tested.
556 * @return {@code true} if the value of the argument is NaN;
557 * {@code false} otherwise.
558 */
559 public static boolean isNaN(double v) {
560 return (v != v);
561 }
562
563 /**
564 * Returns {@code true} if the specified number is infinitely
565 * large in magnitude, {@code false} otherwise.
566 *
567 * @param v the value to be tested.
568 * @return {@code true} if the value of the argument is positive
569 * infinity or negative infinity; {@code false} otherwise.
570 */
571 public static boolean isInfinite(double v) {
572 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
573 }
574
575 /**
576 * Returns {@code true} if the argument is a finite floating-point
577 * value; returns {@code false} otherwise (for NaN and infinity
578 * arguments).
579 *
580 * @param d the {@code double} value to be tested
581 * @return {@code true} if the argument is a finite
582 * floating-point value, {@code false} otherwise.
583 * @since 1.8
584 */
585 public static boolean isFinite(double d) {
586 return Math.abs(d) <= DoubleConsts.MAX_VALUE;
587 }
588
589 /**
590 * The value of the Double.
591 *
592 * @serial
593 */
594 private final double value;
595
596 /**
597 * Constructs a newly allocated {@code Double} object that
598 * represents the primitive {@code double} argument.
599 *
600 * @param value the value to be represented by the {@code Double}.
601 */
602 public Double(double value) {
603 this.value = value;
604 }
605
606 /**
607 * Constructs a newly allocated {@code Double} object that
608 * represents the floating-point value of type {@code double}
609 * represented by the string. The string is converted to a
610 * {@code double} value as if by the {@code valueOf} method.
611 *
612 * @param s a string to be converted to a {@code Double}.
613 * @throws NumberFormatException if the string does not contain a
614 * parsable number.
615 * @see java.lang.Double#valueOf(java.lang.String)
616 */
617 public Double(String s) throws NumberFormatException {
618 value = parseDouble(s);
619 }
620
621 /**
622 * Returns {@code true} if this {@code Double} value is
623 * a Not-a-Number (NaN), {@code false} otherwise.
624 *
625 * @return {@code true} if the value represented by this object is
626 * NaN; {@code false} otherwise.
627 */
628 public boolean isNaN() {
629 return isNaN(value);
630 }
631
632 /**
633 * Returns {@code true} if this {@code Double} value is
634 * infinitely large in magnitude, {@code false} otherwise.
635 *
636 * @return {@code true} if the value represented by this object is
637 * positive infinity or negative infinity;
638 * {@code false} otherwise.
639 */
640 public boolean isInfinite() {
641 return isInfinite(value);
642 }
643
644 /**
645 * Returns a string representation of this {@code Double} object.
646 * The primitive {@code double} value represented by this
647 * object is converted to a string exactly as if by the method
648 * {@code toString} of one argument.
649 *
650 * @return a {@code String} representation of this object.
651 * @see java.lang.Double#toString(double)
652 */
653 public String toString() {
654 return toString(value);
655 }
656
657 /**
658 * Returns the value of this {@code Double} as a {@code byte}
659 * after a narrowing primitive conversion.
660 *
661 * @return the {@code double} value represented by this object
662 * converted to type {@code byte}
663 * @jls 5.1.3 Narrowing Primitive Conversions
664 * @since JDK1.1
665 */
666 public byte byteValue() {
667 return (byte)value;
668 }
669
670 /**
671 * Returns the value of this {@code Double} as a {@code short}
672 * after a narrowing primitive conversion.
673 *
674 * @return the {@code double} value represented by this object
675 * converted to type {@code short}
676 * @jls 5.1.3 Narrowing Primitive Conversions
677 * @since JDK1.1
678 */
679 public short shortValue() {
680 return (short)value;
681 }
682
683 /**
684 * Returns the value of this {@code Double} as an {@code int}
685 * after a narrowing primitive conversion.
686 * @jls 5.1.3 Narrowing Primitive Conversions
687 *
688 * @return the {@code double} value represented by this object
689 * converted to type {@code int}
690 */
691 public int intValue() {
692 return (int)value;
693 }
694
695 /**
696 * Returns the value of this {@code Double} as a {@code long}
697 * after a narrowing primitive conversion.
698 *
699 * @return the {@code double} value represented by this object
700 * converted to type {@code long}
701 * @jls 5.1.3 Narrowing Primitive Conversions
702 */
703 public long longValue() {
704 return (long)value;
705 }
706
707 /**
708 * Returns the value of this {@code Double} as a {@code float}
709 * after a narrowing primitive conversion.
710 *
711 * @return the {@code double} value represented by this object
712 * converted to type {@code float}
713 * @jls 5.1.3 Narrowing Primitive Conversions
714 * @since JDK1.0
715 */
716 public float floatValue() {
717 return (float)value;
718 }
719
720 /**
721 * Returns the {@code double} value of this {@code Double} object.
722 *
723 * @return the {@code double} value represented by this object
724 */
725 public double doubleValue() {
726 return value;
727 }
728
729 /**
730 * Returns a hash code for this {@code Double} object. The
731 * result is the exclusive OR of the two halves of the
732 * {@code long} integer bit representation, exactly as
733 * produced by the method {@link #doubleToLongBits(double)}, of
734 * the primitive {@code double} value represented by this
735 * {@code Double} object. That is, the hash code is the value
736 * of the expression:
737 *
738 * <blockquote>
739 * {@code (int)(v^(v>>>32))}
740 * </blockquote>
741 *
742 * where {@code v} is defined by:
743 *
744 * <blockquote>
745 * {@code long v = Double.doubleToLongBits(this.doubleValue());}
746 * </blockquote>
747 *
748 * @return a {@code hash code} value for this object.
749 */
750 public int hashCode() {
751 long bits = doubleToLongBits(value);
752 return (int)(bits ^ (bits >>> 32));
753 }
754
755 /**
756 * Compares this object against the specified object. The result
757 * is {@code true} if and only if the argument is not
758 * {@code null} and is a {@code Double} object that
759 * represents a {@code double} that has the same value as the
760 * {@code double} represented by this object. For this
761 * purpose, two {@code double} values are considered to be
762 * the same if and only if the method {@link
763 * #doubleToLongBits(double)} returns the identical
764 * {@code long} value when applied to each.
765 *
766 * <p>Note that in most cases, for two instances of class
767 * {@code Double}, {@code d1} and {@code d2}, the
768 * value of {@code d1.equals(d2)} is {@code true} if and
769 * only if
770 *
771 * <blockquote>
772 * {@code d1.doubleValue() == d2.doubleValue()}
773 * </blockquote>
774 *
775 * <p>also has the value {@code true}. However, there are two
776 * exceptions:
777 * <ul>
778 * <li>If {@code d1} and {@code d2} both represent
779 * {@code Double.NaN}, then the {@code equals} method
780 * returns {@code true}, even though
781 * {@code Double.NaN==Double.NaN} has the value
782 * {@code false}.
783 * <li>If {@code d1} represents {@code +0.0} while
784 * {@code d2} represents {@code -0.0}, or vice versa,
785 * the {@code equal} test has the value {@code false},
786 * even though {@code +0.0==-0.0} has the value {@code true}.
787 * </ul>
788 * This definition allows hash tables to operate properly.
789 * @param obj the object to compare with.
790 * @return {@code true} if the objects are the same;
791 * {@code false} otherwise.
792 * @see java.lang.Double#doubleToLongBits(double)
793 */
794 public boolean equals(Object obj) {
795 return (obj instanceof Double)
796 && (doubleToLongBits(((Double)obj).value) ==
797 doubleToLongBits(value));
798 }
799
800 /**
801 * Returns a representation of the specified floating-point value
802 * according to the IEEE 754 floating-point "double
803 * format" bit layout.
804 *
805 * <p>Bit 63 (the bit that is selected by the mask
806 * {@code 0x8000000000000000L}) represents the sign of the
807 * floating-point number. Bits
808 * 62-52 (the bits that are selected by the mask
809 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
810 * (the bits that are selected by the mask
811 * {@code 0x000fffffffffffffL}) represent the significand
812 * (sometimes called the mantissa) of the floating-point number.
813 *
814 * <p>If the argument is positive infinity, the result is
815 * {@code 0x7ff0000000000000L}.
816 *
817 * <p>If the argument is negative infinity, the result is
818 * {@code 0xfff0000000000000L}.
819 *
820 * <p>If the argument is NaN, the result is
821 * {@code 0x7ff8000000000000L}.
822 *
823 * <p>In all cases, the result is a {@code long} integer that, when
824 * given to the {@link #longBitsToDouble(long)} method, will produce a
825 * floating-point value the same as the argument to
826 * {@code doubleToLongBits} (except all NaN values are
827 * collapsed to a single "canonical" NaN value).
828 *
829 * @param value a {@code double} precision floating-point number.
830 * @return the bits that represent the floating-point number.
831 */
832 public static long doubleToLongBits(double value) {
833 long result = doubleToRawLongBits(value);
834 // Check for NaN based on values of bit fields, maximum
835 // exponent and nonzero significand.
836 if ( ((result & DoubleConsts.EXP_BIT_MASK) ==
837 DoubleConsts.EXP_BIT_MASK) &&
838 (result & DoubleConsts.SIGNIF_BIT_MASK) != 0L)
839 result = 0x7ff8000000000000L;
840 return result;
841 }
842
843 /**
844 * Returns a representation of the specified floating-point value
845 * according to the IEEE 754 floating-point "double
846 * format" bit layout, preserving Not-a-Number (NaN) values.
847 *
848 * <p>Bit 63 (the bit that is selected by the mask
849 * {@code 0x8000000000000000L}) represents the sign of the
850 * floating-point number. Bits
851 * 62-52 (the bits that are selected by the mask
852 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
853 * (the bits that are selected by the mask
854 * {@code 0x000fffffffffffffL}) represent the significand
855 * (sometimes called the mantissa) of the floating-point number.
856 *
857 * <p>If the argument is positive infinity, the result is
858 * {@code 0x7ff0000000000000L}.
859 *
860 * <p>If the argument is negative infinity, the result is
861 * {@code 0xfff0000000000000L}.
862 *
863 * <p>If the argument is NaN, the result is the {@code long}
864 * integer representing the actual NaN value. Unlike the
865 * {@code doubleToLongBits} method,
866 * {@code doubleToRawLongBits} does not collapse all the bit
867 * patterns encoding a NaN to a single "canonical" NaN
868 * value.
869 *
870 * <p>In all cases, the result is a {@code long} integer that,
871 * when given to the {@link #longBitsToDouble(long)} method, will
872 * produce a floating-point value the same as the argument to
873 * {@code doubleToRawLongBits}.
874 *
875 * @param value a {@code double} precision floating-point number.
876 * @return the bits that represent the floating-point number.
877 * @since 1.3
878 */
879 public static native long doubleToRawLongBits(double value);
880
881 /**
882 * Returns the {@code double} value corresponding to a given
883 * bit representation.
884 * The argument is considered to be a representation of a
885 * floating-point value according to the IEEE 754 floating-point
886 * "double format" bit layout.
887 *
888 * <p>If the argument is {@code 0x7ff0000000000000L}, the result
889 * is positive infinity.
890 *
891 * <p>If the argument is {@code 0xfff0000000000000L}, the result
892 * is negative infinity.
893 *
894 * <p>If the argument is any value in the range
895 * {@code 0x7ff0000000000001L} through
896 * {@code 0x7fffffffffffffffL} or in the range
897 * {@code 0xfff0000000000001L} through
898 * {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE
899 * 754 floating-point operation provided by Java can distinguish
900 * between two NaN values of the same type with different bit
901 * patterns. Distinct values of NaN are only distinguishable by
902 * use of the {@code Double.doubleToRawLongBits} method.
903 *
904 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
905 * values that can be computed from the argument:
906 *
907 * <blockquote><pre>
908 * int s = ((bits >> 63) == 0) ? 1 : -1;
909 * int e = (int)((bits >> 52) & 0x7ffL);
910 * long m = (e == 0) ?
911 * (bits & 0xfffffffffffffL) << 1 :
912 * (bits & 0xfffffffffffffL) | 0x10000000000000L;
913 * </pre></blockquote>
914 *
915 * Then the floating-point result equals the value of the mathematical
916 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>.
917 *
918 * <p>Note that this method may not be able to return a
919 * {@code double} NaN with exactly same bit pattern as the
920 * {@code long} argument. IEEE 754 distinguishes between two
921 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
922 * differences between the two kinds of NaN are generally not
923 * visible in Java. Arithmetic operations on signaling NaNs turn
924 * them into quiet NaNs with a different, but often similar, bit
925 * pattern. However, on some processors merely copying a
926 * signaling NaN also performs that conversion. In particular,
927 * copying a signaling NaN to return it to the calling method
928 * may perform this conversion. So {@code longBitsToDouble}
929 * may not be able to return a {@code double} with a
930 * signaling NaN bit pattern. Consequently, for some
931 * {@code long} values,
932 * {@code doubleToRawLongBits(longBitsToDouble(start))} may
933 * <i>not</i> equal {@code start}. Moreover, which
934 * particular bit patterns represent signaling NaNs is platform
935 * dependent; although all NaN bit patterns, quiet or signaling,
936 * must be in the NaN range identified above.
937 *
938 * @param bits any {@code long} integer.
939 * @return the {@code double} floating-point value with the same
940 * bit pattern.
941 */
942 public static native double longBitsToDouble(long bits);
943
944 /**
945 * Compares two {@code Double} objects numerically. There
946 * are two ways in which comparisons performed by this method
947 * differ from those performed by the Java language numerical
948 * comparison operators ({@code <, <=, ==, >=, >})
949 * when applied to primitive {@code double} values:
950 * <ul><li>
951 * {@code Double.NaN} is considered by this method
952 * to be equal to itself and greater than all other
953 * {@code double} values (including
954 * {@code Double.POSITIVE_INFINITY}).
955 * <li>
956 * {@code 0.0d} is considered by this method to be greater
957 * than {@code -0.0d}.
958 * </ul>
959 * This ensures that the <i>natural ordering</i> of
960 * {@code Double} objects imposed by this method is <i>consistent
961 * with equals</i>.
962 *
963 * @param anotherDouble the {@code Double} to be compared.
964 * @return the value {@code 0} if {@code anotherDouble} is
965 * numerically equal to this {@code Double}; a value
966 * less than {@code 0} if this {@code Double}
967 * is numerically less than {@code anotherDouble};
968 * and a value greater than {@code 0} if this
969 * {@code Double} is numerically greater than
970 * {@code anotherDouble}.
971 *
972 * @since 1.2
973 */
974 public int compareTo(Double anotherDouble) {
975 return Double.compare(value, anotherDouble.value);
976 }
977
978 /**
979 * Compares the two specified {@code double} values. The sign
980 * of the integer value returned is the same as that of the
981 * integer that would be returned by the call:
982 * <pre>
983 * new Double(d1).compareTo(new Double(d2))
984 * </pre>
985 *
986 * @param d1 the first {@code double} to compare
987 * @param d2 the second {@code double} to compare
988 * @return the value {@code 0} if {@code d1} is
989 * numerically equal to {@code d2}; a value less than
990 * {@code 0} if {@code d1} is numerically less than
991 * {@code d2}; and a value greater than {@code 0}
992 * if {@code d1} is numerically greater than
993 * {@code d2}.
994 * @since 1.4
995 */
996 public static int compare(double d1, double d2) {
997 if (d1 < d2)
998 return -1; // Neither val is NaN, thisVal is smaller
999 if (d1 > d2)
1000 return 1; // Neither val is NaN, thisVal is larger
1001
1002 // Cannot use doubleToRawLongBits because of possibility of NaNs.
1003 long thisBits = Double.doubleToLongBits(d1);
1004 long anotherBits = Double.doubleToLongBits(d2);
1005
1006 return (thisBits == anotherBits ? 0 : // Values are equal
1007 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1008 1)); // (0.0, -0.0) or (NaN, !NaN)
1009 }
1010
1011 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1012 private static final long serialVersionUID = -9172774392245257468L;
1013 }