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