1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. Oracle designates this 9 * particular file as subject to the "Classpath" exception as provided 10 * by Oracle in the LICENSE file that accompanied this code. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 23 * or visit www.oracle.com if you need additional information or have any 24 * questions. 25 */ 26 27 package java.lang; 28 29 import sun.misc.FloatingDecimal; 30 import sun.misc.FpUtils; 31 import sun.misc.DoubleConsts; 32 33 /** 34 * The {@code Double} class wraps a value of the primitive type 35 * {@code double} in an object. An object of type 36 * {@code Double} contains a single field whose type is 37 * {@code double}. 38 * 39 * <p>In addition, this class provides several methods for converting a 40 * {@code double} to a {@code String} and a 41 * {@code String} to a {@code double}, as well as other 42 * constants and methods useful when dealing with a 43 * {@code double}. 44 * 45 * @author Lee Boynton 46 * @author Arthur van Hoff 47 * @author Joseph D. Darcy 48 * @since JDK1.0 49 */ 50 public final class Double extends Number implements Comparable<Double> { 51 /** 52 * A constant holding the positive infinity of type 53 * {@code double}. It is equal to the value returned by 54 * {@code Double.longBitsToDouble(0x7ff0000000000000L)}. 55 */ 56 public static final double POSITIVE_INFINITY = 1.0 / 0.0; 57 58 /** 59 * A constant holding the negative infinity of type 60 * {@code double}. It is equal to the value returned by 61 * {@code Double.longBitsToDouble(0xfff0000000000000L)}. 62 */ 63 public static final double NEGATIVE_INFINITY = -1.0 / 0.0; 64 65 /** 66 * A constant holding a Not-a-Number (NaN) value of type 67 * {@code double}. It is equivalent to the value returned by 68 * {@code Double.longBitsToDouble(0x7ff8000000000000L)}. 69 */ 70 public static final double NaN = 0.0d / 0.0; 71 72 /** 73 * A constant holding the largest positive finite value of type 74 * {@code double}, 75 * (2-2<sup>-52</sup>)·2<sup>1023</sup>. It is equal to 76 * the hexadecimal floating-point literal 77 * {@code 0x1.fffffffffffffP+1023} and also equal to 78 * {@code Double.longBitsToDouble(0x7fefffffffffffffL)}. 79 */ 80 public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308 81 82 /** 83 * A constant holding the smallest positive normal value of type 84 * {@code double}, 2<sup>-1022</sup>. It is equal to the 85 * hexadecimal floating-point literal {@code 0x1.0p-1022} and also 86 * equal to {@code Double.longBitsToDouble(0x0010000000000000L)}. 87 * 88 * @since 1.6 89 */ 90 public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308 91 92 /** 93 * A constant holding the smallest positive nonzero value of type 94 * {@code double}, 2<sup>-1074</sup>. It is equal to the 95 * hexadecimal floating-point literal 96 * {@code 0x0.0000000000001P-1022} and also equal to 97 * {@code Double.longBitsToDouble(0x1L)}. 98 */ 99 public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324 100 101 /** 102 * Maximum exponent a finite {@code double} variable may have. 103 * It is equal to the value returned by 104 * {@code Math.getExponent(Double.MAX_VALUE)}. 105 * 106 * @since 1.6 107 */ 108 public static final int MAX_EXPONENT = 1023; 109 110 /** 111 * Minimum exponent a normalized {@code double} variable may 112 * have. It is equal to the value returned by 113 * {@code Math.getExponent(Double.MIN_NORMAL)}. 114 * 115 * @since 1.6 116 */ 117 public static final int MIN_EXPONENT = -1022; 118 119 /** 120 * The number of bits used to represent a {@code double} value. 121 * 122 * @since 1.5 123 */ 124 public static final int SIZE = 64; 125 126 /** 127 * The number of bytes used to represent a {@code double} value. 128 * 129 * @since 1.8 130 */ 131 public static final int BYTES = SIZE / Byte.SIZE; 132 133 /** 134 * The {@code Class} instance representing the primitive type 135 * {@code double}. 136 * 137 * @since JDK1.1 138 */ 139 @SuppressWarnings("unchecked") 140 public static final Class<Double> TYPE = (Class<Double>) double[].class.getComponentType(); 141 142 /** 143 * Returns a string representation of the {@code double} 144 * argument. All characters mentioned below are ASCII characters. 145 * <ul> 146 * <li>If the argument is NaN, the result is the string 147 * "{@code NaN}". 148 * <li>Otherwise, the result is a string that represents the sign and 149 * magnitude (absolute value) of the argument. If the sign is negative, 150 * the first character of the result is '{@code -}' 151 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character 152 * appears in the result. As for the magnitude <i>m</i>: 153 * <ul> 154 * <li>If <i>m</i> is infinity, it is represented by the characters 155 * {@code "Infinity"}; thus, positive infinity produces the result 156 * {@code "Infinity"} and negative infinity produces the result 157 * {@code "-Infinity"}. 158 * 159 * <li>If <i>m</i> is zero, it is represented by the characters 160 * {@code "0.0"}; thus, negative zero produces the result 161 * {@code "-0.0"} and positive zero produces the result 162 * {@code "0.0"}. 163 * 164 * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less 165 * than 10<sup>7</sup>, then it is represented as the integer part of 166 * <i>m</i>, in decimal form with no leading zeroes, followed by 167 * '{@code .}' ({@code '\u005Cu002E'}), followed by one or 168 * more decimal digits representing the fractional part of <i>m</i>. 169 * 170 * <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or 171 * equal to 10<sup>7</sup>, then it is represented in so-called 172 * "computerized scientific notation." Let <i>n</i> be the unique 173 * integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <} 174 * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the 175 * mathematically exact quotient of <i>m</i> and 176 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The 177 * magnitude is then represented as the integer part of <i>a</i>, 178 * as a single decimal digit, followed by '{@code .}' 179 * ({@code '\u005Cu002E'}), followed by decimal digits 180 * representing the fractional part of <i>a</i>, followed by the 181 * letter '{@code E}' ({@code '\u005Cu0045'}), followed 182 * by a representation of <i>n</i> as a decimal integer, as 183 * produced by the method {@link Integer#toString(int)}. 184 * </ul> 185 * </ul> 186 * How many digits must be printed for the fractional part of 187 * <i>m</i> or <i>a</i>? There must be at least one digit to represent 188 * the fractional part, and beyond that as many, but only as many, more 189 * digits as are needed to uniquely distinguish the argument value from 190 * adjacent values of type {@code double}. That is, suppose that 191 * <i>x</i> is the exact mathematical value represented by the decimal 192 * representation produced by this method for a finite nonzero argument 193 * <i>d</i>. Then <i>d</i> must be the {@code double} value nearest 194 * to <i>x</i>; or if two {@code double} values are equally close 195 * to <i>x</i>, then <i>d</i> must be one of them and the least 196 * significant bit of the significand of <i>d</i> must be {@code 0}. 197 * 198 * <p>To create localized string representations of a floating-point 199 * value, use subclasses of {@link java.text.NumberFormat}. 200 * 201 * @param d the {@code double} to be converted. 202 * @return a string representation of the argument. 203 */ toString(double d)204 public static String toString(double d) { 205 return FloatingDecimal.toJavaFormatString(d); 206 } 207 208 /** 209 * Returns a hexadecimal string representation of the 210 * {@code double} argument. All characters mentioned below 211 * are ASCII characters. 212 * 213 * <ul> 214 * <li>If the argument is NaN, the result is the string 215 * "{@code NaN}". 216 * <li>Otherwise, the result is a string that represents the sign 217 * and magnitude of the argument. If the sign is negative, the 218 * first character of the result is '{@code -}' 219 * ({@code '\u005Cu002D'}); if the sign is positive, no sign 220 * character appears in the result. As for the magnitude <i>m</i>: 221 * 222 * <ul> 223 * <li>If <i>m</i> is infinity, it is represented by the string 224 * {@code "Infinity"}; thus, positive infinity produces the 225 * result {@code "Infinity"} and negative infinity produces 226 * the result {@code "-Infinity"}. 227 * 228 * <li>If <i>m</i> is zero, it is represented by the string 229 * {@code "0x0.0p0"}; thus, negative zero produces the result 230 * {@code "-0x0.0p0"} and positive zero produces the result 231 * {@code "0x0.0p0"}. 232 * 233 * <li>If <i>m</i> is a {@code double} value with a 234 * normalized representation, substrings are used to represent the 235 * significand and exponent fields. The significand is 236 * represented by the characters {@code "0x1."} 237 * followed by a lowercase hexadecimal representation of the rest 238 * of the significand as a fraction. Trailing zeros in the 239 * hexadecimal representation are removed unless all the digits 240 * are zero, in which case a single zero is used. Next, the 241 * exponent is represented by {@code "p"} followed 242 * by a decimal string of the unbiased exponent as if produced by 243 * a call to {@link Integer#toString(int) Integer.toString} on the 244 * exponent value. 245 * 246 * <li>If <i>m</i> is a {@code double} value with a subnormal 247 * representation, the significand is represented by the 248 * characters {@code "0x0."} followed by a 249 * hexadecimal representation of the rest of the significand as a 250 * fraction. Trailing zeros in the hexadecimal representation are 251 * removed. Next, the exponent is represented by 252 * {@code "p-1022"}. Note that there must be at 253 * least one nonzero digit in a subnormal significand. 254 * 255 * </ul> 256 * 257 * </ul> 258 * 259 * <table border> 260 * <caption>Examples</caption> 261 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th> 262 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td> 263 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td> 264 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td> 265 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td> 266 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td> 267 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td> 268 * <tr><td>{@code Double.MAX_VALUE}</td> 269 * <td>{@code 0x1.fffffffffffffp1023}</td> 270 * <tr><td>{@code Minimum Normal Value}</td> 271 * <td>{@code 0x1.0p-1022}</td> 272 * <tr><td>{@code Maximum Subnormal Value}</td> 273 * <td>{@code 0x0.fffffffffffffp-1022}</td> 274 * <tr><td>{@code Double.MIN_VALUE}</td> 275 * <td>{@code 0x0.0000000000001p-1022}</td> 276 * </table> 277 * @param d the {@code double} to be converted. 278 * @return a hex string representation of the argument. 279 * @since 1.5 280 * @author Joseph D. Darcy 281 */ toHexString(double d)282 public static String toHexString(double d) { 283 /* 284 * Modeled after the "a" conversion specifier in C99, section 285 * 7.19.6.1; however, the output of this method is more 286 * tightly specified. 287 */ 288 if (!isFinite(d) ) 289 // For infinity and NaN, use the decimal output. 290 return Double.toString(d); 291 else { 292 // Initialized to maximum size of output. 293 StringBuilder answer = new StringBuilder(24); 294 295 if (Math.copySign(1.0, d) == -1.0) // value is negative, 296 answer.append("-"); // so append sign info 297 298 answer.append("0x"); 299 300 d = Math.abs(d); 301 302 if(d == 0.0) { 303 answer.append("0.0p0"); 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 answer.append('p'); 328 // If the value is subnormal, use the E_min exponent 329 // value for double; otherwise, extract and report d's 330 // exponent (the representation of a subnormal uses 331 // E_min -1). 332 answer.append(subnormal ? 333 DoubleConsts.MIN_EXPONENT: 334 Math.getExponent(d)); 335 } 336 return answer.toString(); 337 } 338 } 339 340 /** 341 * Returns a {@code Double} object holding the 342 * {@code double} value represented by the argument string 343 * {@code s}. 344 * 345 * <p>If {@code s} is {@code null}, then a 346 * {@code NullPointerException} is thrown. 347 * 348 * <p>Leading and trailing whitespace characters in {@code s} 349 * are ignored. Whitespace is removed as if by the {@link 350 * String#trim} method; that is, both ASCII space and control 351 * characters are removed. The rest of {@code s} should 352 * constitute a <i>FloatValue</i> as described by the lexical 353 * syntax rules: 354 * 355 * <blockquote> 356 * <dl> 357 * <dt><i>FloatValue:</i> 358 * <dd><i>Sign<sub>opt</sub></i> {@code NaN} 359 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity} 360 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i> 361 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i> 362 * <dd><i>SignedInteger</i> 363 * </dl> 364 * 365 * <dl> 366 * <dt><i>HexFloatingPointLiteral</i>: 367 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i> 368 * </dl> 369 * 370 * <dl> 371 * <dt><i>HexSignificand:</i> 372 * <dd><i>HexNumeral</i> 373 * <dd><i>HexNumeral</i> {@code .} 374 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub> 375 * </i>{@code .}<i> HexDigits</i> 376 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub> 377 * </i>{@code .} <i>HexDigits</i> 378 * </dl> 379 * 380 * <dl> 381 * <dt><i>BinaryExponent:</i> 382 * <dd><i>BinaryExponentIndicator SignedInteger</i> 383 * </dl> 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 * <pre>{@code 450 * final String Digits = "(\\p{Digit}+)"; 451 * final String HexDigits = "(\\p{XDigit}+)"; 452 * // an exponent is 'e' or 'E' followed by an optionally 453 * // signed decimal integer. 454 * final String Exp = "[eE][+-]?"+Digits; 455 * final String fpRegex = 456 * ("[\\x00-\\x20]*"+ // Optional leading "whitespace" 457 * "[+-]?(" + // Optional sign character 458 * "NaN|" + // "NaN" string 459 * "Infinity|" + // "Infinity" string 460 * 461 * // A decimal floating-point string representing a finite positive 462 * // number without a leading sign has at most five basic pieces: 463 * // Digits . Digits ExponentPart FloatTypeSuffix 464 * // 465 * // Since this method allows integer-only strings as input 466 * // in addition to strings of floating-point literals, the 467 * // two sub-patterns below are simplifications of the grammar 468 * // productions from section 3.10.2 of 469 * // The Java Language Specification. 470 * 471 * // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt 472 * "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+ 473 * 474 * // . Digits ExponentPart_opt FloatTypeSuffix_opt 475 * "(\\.("+Digits+")("+Exp+")?)|"+ 476 * 477 * // Hexadecimal strings 478 * "((" + 479 * // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt 480 * "(0[xX]" + HexDigits + "(\\.)?)|" + 481 * 482 * // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt 483 * "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" + 484 * 485 * ")[pP][+-]?" + Digits + "))" + 486 * "[fFdD]?))" + 487 * "[\\x00-\\x20]*");// Optional trailing "whitespace" 488 * 489 * if (Pattern.matches(fpRegex, myString)) 490 * Double.valueOf(myString); // Will not throw NumberFormatException 491 * else { 492 * // Perform suitable alternative action 493 * } 494 * }</pre> 495 * 496 * @param s the string to be parsed. 497 * @return a {@code Double} object holding the value 498 * represented by the {@code String} argument. 499 * @throws NumberFormatException if the string does not contain a 500 * parsable number. 501 */ valueOf(String s)502 public static Double valueOf(String s) throws NumberFormatException { 503 return new Double(parseDouble(s)); 504 } 505 506 /** 507 * Returns a {@code Double} instance representing the specified 508 * {@code double} value. 509 * If a new {@code Double} instance is not required, this method 510 * should generally be used in preference to the constructor 511 * {@link #Double(double)}, as this method is likely to yield 512 * significantly better space and time performance by caching 513 * frequently requested values. 514 * 515 * @param d a double value. 516 * @return a {@code Double} instance representing {@code d}. 517 * @since 1.5 518 */ valueOf(double d)519 public static Double valueOf(double d) { 520 return new Double(d); 521 } 522 523 /** 524 * Returns a new {@code double} initialized to the value 525 * represented by the specified {@code String}, as performed 526 * by the {@code valueOf} method of class 527 * {@code Double}. 528 * 529 * @param s the string to be parsed. 530 * @return the {@code double} value represented by the string 531 * argument. 532 * @throws NullPointerException if the string is null 533 * @throws NumberFormatException if the string does not contain 534 * a parsable {@code double}. 535 * @see java.lang.Double#valueOf(String) 536 * @since 1.2 537 */ parseDouble(String s)538 public static double parseDouble(String s) throws NumberFormatException { 539 return FloatingDecimal.parseDouble(s); 540 } 541 542 /** 543 * Returns {@code true} if the specified number is a 544 * Not-a-Number (NaN) value, {@code false} otherwise. 545 * 546 * @param v the value to be tested. 547 * @return {@code true} if the value of the argument is NaN; 548 * {@code false} otherwise. 549 */ isNaN(double v)550 public static boolean isNaN(double v) { 551 return (v != v); 552 } 553 554 /** 555 * Returns {@code true} if the specified number is infinitely 556 * large in magnitude, {@code false} otherwise. 557 * 558 * @param v the value to be tested. 559 * @return {@code true} if the value of the argument is positive 560 * infinity or negative infinity; {@code false} otherwise. 561 */ isInfinite(double v)562 public static boolean isInfinite(double v) { 563 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY); 564 } 565 566 /** 567 * Returns {@code true} if the argument is a finite floating-point 568 * value; returns {@code false} otherwise (for NaN and infinity 569 * arguments). 570 * 571 * @param d the {@code double} value to be tested 572 * @return {@code true} if the argument is a finite 573 * floating-point value, {@code false} otherwise. 574 * @since 1.8 575 */ isFinite(double d)576 public static boolean isFinite(double d) { 577 return Math.abs(d) <= DoubleConsts.MAX_VALUE; 578 } 579 580 /** 581 * The value of the Double. 582 * 583 * @serial 584 */ 585 private final double value; 586 587 /** 588 * Constructs a newly allocated {@code Double} object that 589 * represents the primitive {@code double} argument. 590 * 591 * @param value the value to be represented by the {@code Double}. 592 */ Double(double value)593 public Double(double value) { 594 this.value = value; 595 } 596 597 /** 598 * Constructs a newly allocated {@code Double} object that 599 * represents the floating-point value of type {@code double} 600 * represented by the string. The string is converted to a 601 * {@code double} value as if by the {@code valueOf} method. 602 * 603 * @param s a string to be converted to a {@code Double}. 604 * @throws NumberFormatException if the string does not contain a 605 * parsable number. 606 * @see java.lang.Double#valueOf(java.lang.String) 607 */ Double(String s)608 public Double(String s) throws NumberFormatException { 609 value = parseDouble(s); 610 } 611 612 /** 613 * Returns {@code true} if this {@code Double} value is 614 * a Not-a-Number (NaN), {@code false} otherwise. 615 * 616 * @return {@code true} if the value represented by this object is 617 * NaN; {@code false} otherwise. 618 */ isNaN()619 public boolean isNaN() { 620 return isNaN(value); 621 } 622 623 /** 624 * Returns {@code true} if this {@code Double} value is 625 * infinitely large in magnitude, {@code false} otherwise. 626 * 627 * @return {@code true} if the value represented by this object is 628 * positive infinity or negative infinity; 629 * {@code false} otherwise. 630 */ isInfinite()631 public boolean isInfinite() { 632 return isInfinite(value); 633 } 634 635 /** 636 * Returns a string representation of this {@code Double} object. 637 * The primitive {@code double} value represented by this 638 * object is converted to a string exactly as if by the method 639 * {@code toString} of one argument. 640 * 641 * @return a {@code String} representation of this object. 642 * @see java.lang.Double#toString(double) 643 */ toString()644 public String toString() { 645 return toString(value); 646 } 647 648 /** 649 * Returns the value of this {@code Double} as a {@code byte} 650 * after a narrowing primitive conversion. 651 * 652 * @return the {@code double} value represented by this object 653 * converted to type {@code byte} 654 * @jls 5.1.3 Narrowing Primitive Conversions 655 * @since JDK1.1 656 */ byteValue()657 public byte byteValue() { 658 return (byte)value; 659 } 660 661 /** 662 * Returns the value of this {@code Double} as a {@code short} 663 * after a narrowing primitive conversion. 664 * 665 * @return the {@code double} value represented by this object 666 * converted to type {@code short} 667 * @jls 5.1.3 Narrowing Primitive Conversions 668 * @since JDK1.1 669 */ shortValue()670 public short shortValue() { 671 return (short)value; 672 } 673 674 /** 675 * Returns the value of this {@code Double} as an {@code int} 676 * after a narrowing primitive conversion. 677 * @jls 5.1.3 Narrowing Primitive Conversions 678 * 679 * @return the {@code double} value represented by this object 680 * converted to type {@code int} 681 */ intValue()682 public int intValue() { 683 return (int)value; 684 } 685 686 /** 687 * Returns the value of this {@code Double} as a {@code long} 688 * after a narrowing primitive conversion. 689 * 690 * @return the {@code double} value represented by this object 691 * converted to type {@code long} 692 * @jls 5.1.3 Narrowing Primitive Conversions 693 */ longValue()694 public long longValue() { 695 return (long)value; 696 } 697 698 /** 699 * Returns the value of this {@code Double} as a {@code float} 700 * after a narrowing primitive conversion. 701 * 702 * @return the {@code double} value represented by this object 703 * converted to type {@code float} 704 * @jls 5.1.3 Narrowing Primitive Conversions 705 * @since JDK1.0 706 */ floatValue()707 public float floatValue() { 708 return (float)value; 709 } 710 711 /** 712 * Returns the {@code double} value of this {@code Double} object. 713 * 714 * @return the {@code double} value represented by this object 715 */ doubleValue()716 public double doubleValue() { 717 return value; 718 } 719 720 /** 721 * Returns a hash code for this {@code Double} object. The 722 * result is the exclusive OR of the two halves of the 723 * {@code long} integer bit representation, exactly as 724 * produced by the method {@link #doubleToLongBits(double)}, of 725 * the primitive {@code double} value represented by this 726 * {@code Double} object. That is, the hash code is the value 727 * of the expression: 728 * 729 * <blockquote> 730 * {@code (int)(v^(v>>>32))} 731 * </blockquote> 732 * 733 * where {@code v} is defined by: 734 * 735 * <blockquote> 736 * {@code long v = Double.doubleToLongBits(this.doubleValue());} 737 * </blockquote> 738 * 739 * @return a {@code hash code} value for this object. 740 */ 741 @Override hashCode()742 public int hashCode() { 743 return Double.hashCode(value); 744 } 745 746 /** 747 * Returns a hash code for a {@code double} value; compatible with 748 * {@code Double.hashCode()}. 749 * 750 * @param value the value to hash 751 * @return a hash code value for a {@code double} value. 752 * @since 1.8 753 */ hashCode(double value)754 public static int hashCode(double value) { 755 long bits = doubleToLongBits(value); 756 return (int)(bits ^ (bits >>> 32)); 757 } 758 759 /** 760 * Compares this object against the specified object. The result 761 * is {@code true} if and only if the argument is not 762 * {@code null} and is a {@code Double} object that 763 * represents a {@code double} that has the same value as the 764 * {@code double} represented by this object. For this 765 * purpose, two {@code double} values are considered to be 766 * the same if and only if the method {@link 767 * #doubleToLongBits(double)} returns the identical 768 * {@code long} value when applied to each. 769 * 770 * <p>Note that in most cases, for two instances of class 771 * {@code Double}, {@code d1} and {@code d2}, the 772 * value of {@code d1.equals(d2)} is {@code true} if and 773 * only if 774 * 775 * <blockquote> 776 * {@code d1.doubleValue() == d2.doubleValue()} 777 * </blockquote> 778 * 779 * <p>also has the value {@code true}. However, there are two 780 * exceptions: 781 * <ul> 782 * <li>If {@code d1} and {@code d2} both represent 783 * {@code Double.NaN}, then the {@code equals} method 784 * returns {@code true}, even though 785 * {@code Double.NaN==Double.NaN} has the value 786 * {@code false}. 787 * <li>If {@code d1} represents {@code +0.0} while 788 * {@code d2} represents {@code -0.0}, or vice versa, 789 * the {@code equal} test has the value {@code false}, 790 * even though {@code +0.0==-0.0} has the value {@code true}. 791 * </ul> 792 * This definition allows hash tables to operate properly. 793 * @param obj the object to compare with. 794 * @return {@code true} if the objects are the same; 795 * {@code false} otherwise. 796 * @see java.lang.Double#doubleToLongBits(double) 797 */ equals(Object obj)798 public boolean equals(Object obj) { 799 return (obj instanceof Double) 800 && (doubleToLongBits(((Double)obj).value) == 801 doubleToLongBits(value)); 802 } 803 804 /** 805 * Returns a representation of the specified floating-point value 806 * according to the IEEE 754 floating-point "double 807 * format" bit layout. 808 * 809 * <p>Bit 63 (the bit that is selected by the mask 810 * {@code 0x8000000000000000L}) represents the sign of the 811 * floating-point number. Bits 812 * 62-52 (the bits that are selected by the mask 813 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0 814 * (the bits that are selected by the mask 815 * {@code 0x000fffffffffffffL}) represent the significand 816 * (sometimes called the mantissa) of the floating-point number. 817 * 818 * <p>If the argument is positive infinity, the result is 819 * {@code 0x7ff0000000000000L}. 820 * 821 * <p>If the argument is negative infinity, the result is 822 * {@code 0xfff0000000000000L}. 823 * 824 * <p>If the argument is NaN, the result is 825 * {@code 0x7ff8000000000000L}. 826 * 827 * <p>In all cases, the result is a {@code long} integer that, when 828 * given to the {@link #longBitsToDouble(long)} method, will produce a 829 * floating-point value the same as the argument to 830 * {@code doubleToLongBits} (except all NaN values are 831 * collapsed to a single "canonical" NaN value). 832 * 833 * @param value a {@code double} precision floating-point number. 834 * @return the bits that represent the floating-point number. 835 */ doubleToLongBits(double value)836 public static long doubleToLongBits(double value) { 837 long result = doubleToRawLongBits(value); 838 // Check for NaN based on values of bit fields, maximum 839 // exponent and nonzero significand. 840 if ( ((result & DoubleConsts.EXP_BIT_MASK) == 841 DoubleConsts.EXP_BIT_MASK) && 842 (result & DoubleConsts.SIGNIF_BIT_MASK) != 0L) 843 result = 0x7ff8000000000000L; 844 return result; 845 } 846 847 /** 848 * Returns a representation of the specified floating-point value 849 * according to the IEEE 754 floating-point "double 850 * format" bit layout, preserving Not-a-Number (NaN) values. 851 * 852 * <p>Bit 63 (the bit that is selected by the mask 853 * {@code 0x8000000000000000L}) represents the sign of the 854 * floating-point number. Bits 855 * 62-52 (the bits that are selected by the mask 856 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0 857 * (the bits that are selected by the mask 858 * {@code 0x000fffffffffffffL}) represent the significand 859 * (sometimes called the mantissa) of the floating-point number. 860 * 861 * <p>If the argument is positive infinity, the result is 862 * {@code 0x7ff0000000000000L}. 863 * 864 * <p>If the argument is negative infinity, the result is 865 * {@code 0xfff0000000000000L}. 866 * 867 * <p>If the argument is NaN, the result is the {@code long} 868 * integer representing the actual NaN value. Unlike the 869 * {@code doubleToLongBits} method, 870 * {@code doubleToRawLongBits} does not collapse all the bit 871 * patterns encoding a NaN to a single "canonical" NaN 872 * value. 873 * 874 * <p>In all cases, the result is a {@code long} integer that, 875 * when given to the {@link #longBitsToDouble(long)} method, will 876 * produce a floating-point value the same as the argument to 877 * {@code doubleToRawLongBits}. 878 * 879 * @param value a {@code double} precision floating-point number. 880 * @return the bits that represent the floating-point number. 881 * @since 1.3 882 */ doubleToRawLongBits(double value)883 public static native long doubleToRawLongBits(double value); 884 885 /** 886 * Returns the {@code double} value corresponding to a given 887 * bit representation. 888 * The argument is considered to be a representation of a 889 * floating-point value according to the IEEE 754 floating-point 890 * "double format" bit layout. 891 * 892 * <p>If the argument is {@code 0x7ff0000000000000L}, the result 893 * is positive infinity. 894 * 895 * <p>If the argument is {@code 0xfff0000000000000L}, the result 896 * is negative infinity. 897 * 898 * <p>If the argument is any value in the range 899 * {@code 0x7ff0000000000001L} through 900 * {@code 0x7fffffffffffffffL} or in the range 901 * {@code 0xfff0000000000001L} through 902 * {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE 903 * 754 floating-point operation provided by Java can distinguish 904 * between two NaN values of the same type with different bit 905 * patterns. Distinct values of NaN are only distinguishable by 906 * use of the {@code Double.doubleToRawLongBits} method. 907 * 908 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three 909 * values that can be computed from the argument: 910 * 911 * <blockquote><pre>{@code 912 * int s = ((bits >> 63) == 0) ? 1 : -1; 913 * int e = (int)((bits >> 52) & 0x7ffL); 914 * long m = (e == 0) ? 915 * (bits & 0xfffffffffffffL) << 1 : 916 * (bits & 0xfffffffffffffL) | 0x10000000000000L; 917 * }</pre></blockquote> 918 * 919 * Then the floating-point result equals the value of the mathematical 920 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>. 921 * 922 * <p>Note that this method may not be able to return a 923 * {@code double} NaN with exactly same bit pattern as the 924 * {@code long} argument. IEEE 754 distinguishes between two 925 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The 926 * differences between the two kinds of NaN are generally not 927 * visible in Java. Arithmetic operations on signaling NaNs turn 928 * them into quiet NaNs with a different, but often similar, bit 929 * pattern. However, on some processors merely copying a 930 * signaling NaN also performs that conversion. In particular, 931 * copying a signaling NaN to return it to the calling method 932 * may perform this conversion. So {@code longBitsToDouble} 933 * may not be able to return a {@code double} with a 934 * signaling NaN bit pattern. Consequently, for some 935 * {@code long} values, 936 * {@code doubleToRawLongBits(longBitsToDouble(start))} may 937 * <i>not</i> equal {@code start}. Moreover, which 938 * particular bit patterns represent signaling NaNs is platform 939 * dependent; although all NaN bit patterns, quiet or signaling, 940 * must be in the NaN range identified above. 941 * 942 * @param bits any {@code long} integer. 943 * @return the {@code double} floating-point value with the same 944 * bit pattern. 945 */ longBitsToDouble(long bits)946 public static native double longBitsToDouble(long bits); 947 948 /** 949 * Compares two {@code Double} objects numerically. There 950 * are two ways in which comparisons performed by this method 951 * differ from those performed by the Java language numerical 952 * comparison operators ({@code <, <=, ==, >=, >}) 953 * when applied to primitive {@code double} values: 954 * <ul><li> 955 * {@code Double.NaN} is considered by this method 956 * to be equal to itself and greater than all other 957 * {@code double} values (including 958 * {@code Double.POSITIVE_INFINITY}). 959 * <li> 960 * {@code 0.0d} is considered by this method to be greater 961 * than {@code -0.0d}. 962 * </ul> 963 * This ensures that the <i>natural ordering</i> of 964 * {@code Double} objects imposed by this method is <i>consistent 965 * with equals</i>. 966 * 967 * @param anotherDouble the {@code Double} to be compared. 968 * @return the value {@code 0} if {@code anotherDouble} is 969 * numerically equal to this {@code Double}; a value 970 * less than {@code 0} if this {@code Double} 971 * is numerically less than {@code anotherDouble}; 972 * and a value greater than {@code 0} if this 973 * {@code Double} is numerically greater than 974 * {@code anotherDouble}. 975 * 976 * @since 1.2 977 */ compareTo(Double anotherDouble)978 public int compareTo(Double anotherDouble) { 979 return Double.compare(value, anotherDouble.value); 980 } 981 982 /** 983 * Compares the two specified {@code double} values. The sign 984 * of the integer value returned is the same as that of the 985 * integer that would be returned by the call: 986 * <pre> 987 * new Double(d1).compareTo(new Double(d2)) 988 * </pre> 989 * 990 * @param d1 the first {@code double} to compare 991 * @param d2 the second {@code double} to compare 992 * @return the value {@code 0} if {@code d1} is 993 * numerically equal to {@code d2}; a value less than 994 * {@code 0} if {@code d1} is numerically less than 995 * {@code d2}; and a value greater than {@code 0} 996 * if {@code d1} is numerically greater than 997 * {@code d2}. 998 * @since 1.4 999 */ compare(double d1, double d2)1000 public static int compare(double d1, double d2) { 1001 if (d1 < d2) 1002 return -1; // Neither val is NaN, thisVal is smaller 1003 if (d1 > d2) 1004 return 1; // Neither val is NaN, thisVal is larger 1005 1006 // Cannot use doubleToRawLongBits because of possibility of NaNs. 1007 long thisBits = Double.doubleToLongBits(d1); 1008 long anotherBits = Double.doubleToLongBits(d2); 1009 1010 return (thisBits == anotherBits ? 0 : // Values are equal 1011 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN) 1012 1)); // (0.0, -0.0) or (NaN, !NaN) 1013 } 1014 1015 /** 1016 * Adds two {@code double} values together as per the + operator. 1017 * 1018 * @param a the first operand 1019 * @param b the second operand 1020 * @return the sum of {@code a} and {@code b} 1021 * @jls 4.2.4 Floating-Point Operations 1022 * @see java.util.function.BinaryOperator 1023 * @since 1.8 1024 */ sum(double a, double b)1025 public static double sum(double a, double b) { 1026 return a + b; 1027 } 1028 1029 /** 1030 * Returns the greater of two {@code double} values 1031 * as if by calling {@link Math#max(double, double) Math.max}. 1032 * 1033 * @param a the first operand 1034 * @param b the second operand 1035 * @return the greater of {@code a} and {@code b} 1036 * @see java.util.function.BinaryOperator 1037 * @since 1.8 1038 */ max(double a, double b)1039 public static double max(double a, double b) { 1040 return Math.max(a, b); 1041 } 1042 1043 /** 1044 * Returns the smaller of two {@code double} values 1045 * as if by calling {@link Math#min(double, double) Math.min}. 1046 * 1047 * @param a the first operand 1048 * @param b the second operand 1049 * @return the smaller of {@code a} and {@code b}. 1050 * @see java.util.function.BinaryOperator 1051 * @since 1.8 1052 */ min(double a, double b)1053 public static double min(double a, double b) { 1054 return Math.min(a, b); 1055 } 1056 1057 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 1058 private static final long serialVersionUID = -9172774392245257468L; 1059 } 1060