1 /* 2 * Copyright 1994-2009 Sun Microsystems, Inc. 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. Sun designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 22 * CA 95054 USA or visit www.sun.com if you need additional information or 23 * have any 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 public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double"); 132 133 /** 134 * Returns a string representation of the {@code double} 135 * argument. All characters mentioned below are ASCII characters. 136 * <ul> 137 * <li>If the argument is NaN, the result is the string 138 * "{@code NaN}". 139 * <li>Otherwise, the result is a string that represents the sign and 140 * magnitude (absolute value) of the argument. If the sign is negative, 141 * the first character of the result is '{@code -}' 142 * (<code>'\u002D'</code>); if the sign is positive, no sign character 143 * appears in the result. As for the magnitude <i>m</i>: 144 * <ul> 145 * <li>If <i>m</i> is infinity, it is represented by the characters 146 * {@code "Infinity"}; thus, positive infinity produces the result 147 * {@code "Infinity"} and negative infinity produces the result 148 * {@code "-Infinity"}. 149 * 150 * <li>If <i>m</i> is zero, it is represented by the characters 151 * {@code "0.0"}; thus, negative zero produces the result 152 * {@code "-0.0"} and positive zero produces the result 153 * {@code "0.0"}. 154 * 155 * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less 156 * than 10<sup>7</sup>, then it is represented as the integer part of 157 * <i>m</i>, in decimal form with no leading zeroes, followed by 158 * '{@code .}' (<code>'\u002E'</code>), followed by one or 159 * more decimal digits representing the fractional part of <i>m</i>. 160 * 161 * <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or 162 * equal to 10<sup>7</sup>, then it is represented in so-called 163 * "computerized scientific notation." Let <i>n</i> be the unique 164 * integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <} 165 * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the 166 * mathematically exact quotient of <i>m</i> and 167 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The 168 * magnitude is then represented as the integer part of <i>a</i>, 169 * as a single decimal digit, followed by '{@code .}' 170 * (<code>'\u002E'</code>), followed by decimal digits 171 * representing the fractional part of <i>a</i>, followed by the 172 * letter '{@code E}' (<code>'\u0045'</code>), followed 173 * by a representation of <i>n</i> as a decimal integer, as 174 * produced by the method {@link Integer#toString(int)}. 175 * </ul> 176 * </ul> 177 * How many digits must be printed for the fractional part of 178 * <i>m</i> or <i>a</i>? There must be at least one digit to represent 179 * the fractional part, and beyond that as many, but only as many, more 180 * digits as are needed to uniquely distinguish the argument value from 181 * adjacent values of type {@code double}. That is, suppose that 182 * <i>x</i> is the exact mathematical value represented by the decimal 183 * representation produced by this method for a finite nonzero argument 184 * <i>d</i>. Then <i>d</i> must be the {@code double} value nearest 185 * to <i>x</i>; or if two {@code double} values are equally close 186 * to <i>x</i>, then <i>d</i> must be one of them and the least 187 * significant bit of the significand of <i>d</i> must be {@code 0}. 188 * 189 * <p>To create localized string representations of a floating-point 190 * value, use subclasses of {@link java.text.NumberFormat}. 191 * 192 * @param d the {@code double} to be converted. 193 * @return a string representation of the argument. 194 */ 195 public static String toString(double d) { 196 return new FloatingDecimal(d).toJavaFormatString(); 197 } 198 199 /** 200 * Returns a hexadecimal string representation of the 201 * {@code double} argument. All characters mentioned below 202 * are ASCII characters. 203 * 204 * <ul> 205 * <li>If the argument is NaN, the result is the string 206 * "{@code NaN}". 207 * <li>Otherwise, the result is a string that represents the sign 208 * and magnitude of the argument. If the sign is negative, the 209 * first character of the result is '{@code -}' 210 * (<code>'\u002D'</code>); if the sign is positive, no sign 211 * character appears in the result. As for the magnitude <i>m</i>: 212 * 213 * <ul> 214 * <li>If <i>m</i> is infinity, it is represented by the string 215 * {@code "Infinity"}; thus, positive infinity produces the 216 * result {@code "Infinity"} and negative infinity produces 217 * the result {@code "-Infinity"}. 218 * 219 * <li>If <i>m</i> is zero, it is represented by the string 220 * {@code "0x0.0p0"}; thus, negative zero produces the result 221 * {@code "-0x0.0p0"} and positive zero produces the result 222 * {@code "0x0.0p0"}. 223 * 224 * <li>If <i>m</i> is a {@code double} value with a 225 * normalized representation, substrings are used to represent the 226 * significand and exponent fields. The significand is 227 * represented by the characters {@code "0x1."} 228 * followed by a lowercase hexadecimal representation of the rest 229 * of the significand as a fraction. Trailing zeros in the 230 * hexadecimal representation are removed unless all the digits 231 * are zero, in which case a single zero is used. Next, the 232 * exponent is represented by {@code "p"} followed 233 * by a decimal string of the unbiased exponent as if produced by 234 * a call to {@link Integer#toString(int) Integer.toString} on the 235 * exponent value. 236 * 237 * <li>If <i>m</i> is a {@code double} value with a subnormal 238 * representation, the significand is represented by the 239 * characters {@code "0x0."} followed by a 240 * hexadecimal representation of the rest of the significand as a 241 * fraction. Trailing zeros in the hexadecimal representation are 242 * removed. Next, the exponent is represented by 243 * {@code "p-1022"}. Note that there must be at 244 * least one nonzero digit in a subnormal significand. 245 * 246 * </ul> 247 * 248 * </ul> 249 * 250 * <table border> 251 * <caption><h3>Examples</h3></caption> 252 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th> 253 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td> 254 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td> 255 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td> 256 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td> 257 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td> 258 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td> 259 * <tr><td>{@code Double.MAX_VALUE}</td> 260 * <td>{@code 0x1.fffffffffffffp1023}</td> 261 * <tr><td>{@code Minimum Normal Value}</td> 262 * <td>{@code 0x1.0p-1022}</td> 263 * <tr><td>{@code Maximum Subnormal Value}</td> 264 * <td>{@code 0x0.fffffffffffffp-1022}</td> 265 * <tr><td>{@code Double.MIN_VALUE}</td> 266 * <td>{@code 0x0.0000000000001p-1022}</td> 267 * </table> 268 * @param d the {@code double} to be converted. 269 * @return a hex string representation of the argument. 270 * @since 1.5 271 * @author Joseph D. Darcy 272 */ 273 public static String toHexString(double d) { 274 /* 275 * Modeled after the "a" conversion specifier in C99, section 276 * 7.19.6.1; however, the output of this method is more 277 * tightly specified. 278 */ 279 if (!FpUtils.isFinite(d) ) 280 // For infinity and NaN, use the decimal output. 281 return Double.toString(d); 282 else { 283 // Initialized to maximum size of output. 284 StringBuffer answer = new StringBuffer(24); 285 286 if (FpUtils.rawCopySign(1.0, d) == -1.0) // value is negative, 287 answer.append("-"); // so append sign info 288 289 answer.append("0x"); 290 291 d = Math.abs(d); 292 293 if(d == 0.0) { 294 answer.append("0.0p0"); 295 } 296 else { 297 boolean subnormal = (d < DoubleConsts.MIN_NORMAL); 298 299 // Isolate significand bits and OR in a high-order bit 300 // so that the string representation has a known 301 // length. 302 long signifBits = (Double.doubleToLongBits(d) 303 & DoubleConsts.SIGNIF_BIT_MASK) | 304 0x1000000000000000L; 305 306 // Subnormal values have a 0 implicit bit; normal 307 // values have a 1 implicit bit. 308 answer.append(subnormal ? "0." : "1."); 309 310 // Isolate the low-order 13 digits of the hex 311 // representation. If all the digits are zero, 312 // replace with a single 0; otherwise, remove all 313 // trailing zeros. 314 String signif = Long.toHexString(signifBits).substring(3,16); 315 answer.append(signif.equals("0000000000000") ? // 13 zeros 316 "0": 317 signif.replaceFirst("0{1,12}$", "")); 318 319 // If the value is subnormal, use the E_min exponent 320 // value for double; otherwise, extract and report d's 321 // exponent (the representation of a subnormal uses 322 // E_min -1). 323 answer.append("p" + (subnormal ? 324 DoubleConsts.MIN_EXPONENT: 325 FpUtils.getExponent(d) )); 326 } 327 return answer.toString(); 328 } 329 } 330 331 /** 332 * Returns a {@code Double} object holding the 333 * {@code double} value represented by the argument string 334 * {@code s}. 335 * 336 * <p>If {@code s} is {@code null}, then a 337 * {@code NullPointerException} is thrown. 338 * 339 * <p>Leading and trailing whitespace characters in {@code s} 340 * are ignored. Whitespace is removed as if by the {@link 341 * String#trim} method; that is, both ASCII space and control 342 * characters are removed. The rest of {@code s} should 343 * constitute a <i>FloatValue</i> as described by the lexical 344 * syntax rules: 345 * 346 * <blockquote> 347 * <dl> 348 * <dt><i>FloatValue:</i> 349 * <dd><i>Sign<sub>opt</sub></i> {@code NaN} 350 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity} 351 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i> 352 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i> 353 * <dd><i>SignedInteger</i> 354 * </dl> 355 * 356 * <p> 357 * 358 * <dl> 359 * <dt><i>HexFloatingPointLiteral</i>: 360 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i> 361 * </dl> 362 * 363 * <p> 364 * 365 * <dl> 366 * <dt><i>HexSignificand:</i> 367 * <dd><i>HexNumeral</i> 368 * <dd><i>HexNumeral</i> {@code .} 369 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub> 370 * </i>{@code .}<i> HexDigits</i> 371 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub> 372 * </i>{@code .} <i>HexDigits</i> 373 * </dl> 374 * 375 * <p> 376 * 377 * <dl> 378 * <dt><i>BinaryExponent:</i> 379 * <dd><i>BinaryExponentIndicator SignedInteger</i> 380 * </dl> 381 * 382 * <p> 383 * 384 * <dl> 385 * <dt><i>BinaryExponentIndicator:</i> 386 * <dd>{@code p} 387 * <dd>{@code P} 388 * </dl> 389 * 390 * </blockquote> 391 * 392 * where <i>Sign</i>, <i>FloatingPointLiteral</i>, 393 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and 394 * <i>FloatTypeSuffix</i> are as defined in the lexical structure 395 * sections of the <a 396 * href="http://java.sun.com/docs/books/jls/html/">Java Language 397 * Specification</a>. If {@code s} does not have the form of 398 * a <i>FloatValue</i>, then a {@code NumberFormatException} 399 * is thrown. Otherwise, {@code s} is regarded as 400 * representing an exact decimal value in the usual 401 * "computerized scientific notation" or as an exact 402 * hexadecimal value; this exact numerical value is then 403 * conceptually converted to an "infinitely precise" 404 * binary value that is then rounded to type {@code double} 405 * by the usual round-to-nearest rule of IEEE 754 floating-point 406 * arithmetic, which includes preserving the sign of a zero 407 * value. 408 * 409 * Note that the round-to-nearest rule also implies overflow and 410 * underflow behaviour; if the exact value of {@code s} is large 411 * enough in magnitude (greater than or equal to ({@link 412 * #MAX_VALUE} + {@link Math#ulp(double) ulp(MAX_VALUE)}/2), 413 * rounding to {@code double} will result in an infinity and if the 414 * exact value of {@code s} is small enough in magnitude (less 415 * than or equal to {@link #MIN_VALUE}/2), rounding to float will 416 * result in a zero. 417 * 418 * Finally, after rounding a {@code Double} object representing 419 * this {@code double} value is returned. 420 * 421 * <p> To interpret localized string representations of a 422 * floating-point value, use subclasses of {@link 423 * java.text.NumberFormat}. 424 * 425 * <p>Note that trailing format specifiers, specifiers that 426 * determine the type of a floating-point literal 427 * ({@code 1.0f} is a {@code float} value; 428 * {@code 1.0d} is a {@code double} value), do 429 * <em>not</em> influence the results of this method. In other 430 * words, the numerical value of the input string is converted 431 * directly to the target floating-point type. The two-step 432 * sequence of conversions, string to {@code float} followed 433 * by {@code float} to {@code double}, is <em>not</em> 434 * equivalent to converting a string directly to 435 * {@code double}. For example, the {@code float} 436 * literal {@code 0.1f} is equal to the {@code double} 437 * value {@code 0.10000000149011612}; the {@code float} 438 * literal {@code 0.1f} represents a different numerical 439 * value than the {@code double} literal 440 * {@code 0.1}. (The numerical value 0.1 cannot be exactly 441 * represented in a binary floating-point number.) 442 * 443 * <p>To avoid calling this method on an invalid string and having 444 * a {@code NumberFormatException} be thrown, the regular 445 * expression below can be used to screen the input string: 446 * 447 * <code> 448 * <pre> 449 * final String Digits = "(\\p{Digit}+)"; 450 * final String HexDigits = "(\\p{XDigit}+)"; 451 * // an exponent is 'e' or 'E' followed by an optionally 452 * // signed decimal integer. 453 * final String Exp = "[eE][+-]?"+Digits; 454 * final String fpRegex = 455 * ("[\\x00-\\x20]*"+ // Optional leading "whitespace" 456 * "[+-]?(" + // Optional sign character 457 * "NaN|" + // "NaN" string 458 * "Infinity|" + // "Infinity" string 459 * 460 * // A decimal floating-point string representing a finite positive 461 * // number without a leading sign has at most five basic pieces: 462 * // Digits . Digits ExponentPart FloatTypeSuffix 463 * // 464 * // Since this method allows integer-only strings as input 465 * // in addition to strings of floating-point literals, the 466 * // two sub-patterns below are simplifications of the grammar 467 * // productions from the Java Language Specification, 2nd 468 * // edition, section 3.10.2. 469 * 470 * // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt 471 * "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+ 472 * 473 * // . Digits ExponentPart_opt FloatTypeSuffix_opt 474 * "(\\.("+Digits+")("+Exp+")?)|"+ 475 * 476 * // Hexadecimal strings 477 * "((" + 478 * // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt 479 * "(0[xX]" + HexDigits + "(\\.)?)|" + 480 * 481 * // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt 482 * "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" + 483 * 484 * ")[pP][+-]?" + Digits + "))" + 485 * "[fFdD]?))" + 486 * "[\\x00-\\x20]*");// Optional trailing "whitespace" 487 * 488 * if (Pattern.matches(fpRegex, myString)) 489 * Double.valueOf(myString); // Will not throw NumberFormatException 490 * else { 491 * // Perform suitable alternative action 492 * } 493 * </pre> 494 * </code> 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 */ 502 public static Double valueOf(String s) throws NumberFormatException { 503 return new Double(FloatingDecimal.readJavaFormatString(s).doubleValue()); 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 */ 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 */ 538 public static double parseDouble(String s) throws NumberFormatException { 539 return FloatingDecimal.readJavaFormatString(s).doubleValue(); 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 */ 550 static public 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 */ 562 static public boolean isInfinite(double v) { 563 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY); 564 } 565 566 /** 567 * The value of the Double. 568 * 569 * @serial 570 */ 571 private final double value; 572 573 /** 574 * Constructs a newly allocated {@code Double} object that 575 * represents the primitive {@code double} argument. 576 * 577 * @param value the value to be represented by the {@code Double}. 578 */ 579 public Double(double value) { 580 this.value = value; 581 } 582 583 /** 584 * Constructs a newly allocated {@code Double} object that 585 * represents the floating-point value of type {@code double} 586 * represented by the string. The string is converted to a 587 * {@code double} value as if by the {@code valueOf} method. 588 * 589 * @param s a string to be converted to a {@code Double}. 590 * @throws NumberFormatException if the string does not contain a 591 * parsable number. 592 * @see java.lang.Double#valueOf(java.lang.String) 593 */ 594 public Double(String s) throws NumberFormatException { 595 // REMIND: this is inefficient 596 this(valueOf(s).doubleValue()); 597 } 598 599 /** 600 * Returns {@code true} if this {@code Double} value is 601 * a Not-a-Number (NaN), {@code false} otherwise. 602 * 603 * @return {@code true} if the value represented by this object is 604 * NaN; {@code false} otherwise. 605 */ 606 public boolean isNaN() { 607 return isNaN(value); 608 } 609 610 /** 611 * Returns {@code true} if this {@code Double} value is 612 * infinitely large in magnitude, {@code false} otherwise. 613 * 614 * @return {@code true} if the value represented by this object is 615 * positive infinity or negative infinity; 616 * {@code false} otherwise. 617 */ 618 public boolean isInfinite() { 619 return isInfinite(value); 620 } 621 622 /** 623 * Returns a string representation of this {@code Double} object. 624 * The primitive {@code double} value represented by this 625 * object is converted to a string exactly as if by the method 626 * {@code toString} of one argument. 627 * 628 * @return a {@code String} representation of this object. 629 * @see java.lang.Double#toString(double) 630 */ 631 public String toString() { 632 return toString(value); 633 } 634 635 /** 636 * Returns the value of this {@code Double} as a {@code byte} (by 637 * casting to a {@code byte}). 638 * 639 * @return the {@code double} value represented by this object 640 * converted to type {@code byte} 641 * @since JDK1.1 642 */ 643 public byte byteValue() { 644 return (byte)value; 645 } 646 647 /** 648 * Returns the value of this {@code Double} as a 649 * {@code short} (by casting to a {@code short}). 650 * 651 * @return the {@code double} value represented by this object 652 * converted to type {@code short} 653 * @since JDK1.1 654 */ 655 public short shortValue() { 656 return (short)value; 657 } 658 659 /** 660 * Returns the value of this {@code Double} as an 661 * {@code int} (by casting to type {@code int}). 662 * 663 * @return the {@code double} value represented by this object 664 * converted to type {@code int} 665 */ 666 public int intValue() { 667 return (int)value; 668 } 669 670 /** 671 * Returns the value of this {@code Double} as a 672 * {@code long} (by casting to type {@code long}). 673 * 674 * @return the {@code double} value represented by this object 675 * converted to type {@code long} 676 */ 677 public long longValue() { 678 return (long)value; 679 } 680 681 /** 682 * Returns the {@code float} value of this 683 * {@code Double} object. 684 * 685 * @return the {@code double} value represented by this object 686 * converted to type {@code float} 687 * @since JDK1.0 688 */ 689 public float floatValue() { 690 return (float)value; 691 } 692 693 /** 694 * Returns the {@code double} value of this 695 * {@code Double} object. 696 * 697 * @return the {@code double} value represented by this object 698 */ 699 public double doubleValue() { 700 return (double)value; 701 } 702 703 /** 704 * Returns a hash code for this {@code Double} object. The 705 * result is the exclusive OR of the two halves of the 706 * {@code long} integer bit representation, exactly as 707 * produced by the method {@link #doubleToLongBits(double)}, of 708 * the primitive {@code double} value represented by this 709 * {@code Double} object. That is, the hash code is the value 710 * of the expression: 711 * 712 * <blockquote> 713 * {@code (int)(v^(v>>>32))} 714 * </blockquote> 715 * 716 * where {@code v} is defined by: 717 * 718 * <blockquote> 719 * {@code long v = Double.doubleToLongBits(this.doubleValue());} 720 * </blockquote> 721 * 722 * @return a {@code hash code} value for this object. 723 */ 724 public int hashCode() { 725 long bits = doubleToLongBits(value); 726 return (int)(bits ^ (bits >>> 32)); 727 } 728 729 /** 730 * Compares this object against the specified object. The result 731 * is {@code true} if and only if the argument is not 732 * {@code null} and is a {@code Double} object that 733 * represents a {@code double} that has the same value as the 734 * {@code double} represented by this object. For this 735 * purpose, two {@code double} values are considered to be 736 * the same if and only if the method {@link 737 * #doubleToLongBits(double)} returns the identical 738 * {@code long} value when applied to each. 739 * 740 * <p>Note that in most cases, for two instances of class 741 * {@code Double}, {@code d1} and {@code d2}, the 742 * value of {@code d1.equals(d2)} is {@code true} if and 743 * only if 744 * 745 * <blockquote> 746 * {@code d1.doubleValue() == d2.doubleValue()} 747 * </blockquote> 748 * 749 * <p>also has the value {@code true}. However, there are two 750 * exceptions: 751 * <ul> 752 * <li>If {@code d1} and {@code d2} both represent 753 * {@code Double.NaN}, then the {@code equals} method 754 * returns {@code true}, even though 755 * {@code Double.NaN==Double.NaN} has the value 756 * {@code false}. 757 * <li>If {@code d1} represents {@code +0.0} while 758 * {@code d2} represents {@code -0.0}, or vice versa, 759 * the {@code equal} test has the value {@code false}, 760 * even though {@code +0.0==-0.0} has the value {@code true}. 761 * </ul> 762 * This definition allows hash tables to operate properly. 763 * @param obj the object to compare with. 764 * @return {@code true} if the objects are the same; 765 * {@code false} otherwise. 766 * @see java.lang.Double#doubleToLongBits(double) 767 */ 768 public boolean equals(Object obj) { 769 return (obj instanceof Double) 770 && (doubleToLongBits(((Double)obj).value) == 771 doubleToLongBits(value)); 772 } 773 774 /** 775 * Returns a representation of the specified floating-point value 776 * according to the IEEE 754 floating-point "double 777 * format" bit layout. 778 * 779 * <p>Bit 63 (the bit that is selected by the mask 780 * {@code 0x8000000000000000L}) represents the sign of the 781 * floating-point number. Bits 782 * 62-52 (the bits that are selected by the mask 783 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0 784 * (the bits that are selected by the mask 785 * {@code 0x000fffffffffffffL}) represent the significand 786 * (sometimes called the mantissa) of the floating-point number. 787 * 788 * <p>If the argument is positive infinity, the result is 789 * {@code 0x7ff0000000000000L}. 790 * 791 * <p>If the argument is negative infinity, the result is 792 * {@code 0xfff0000000000000L}. 793 * 794 * <p>If the argument is NaN, the result is 795 * {@code 0x7ff8000000000000L}. 796 * 797 * <p>In all cases, the result is a {@code long} integer that, when 798 * given to the {@link #longBitsToDouble(long)} method, will produce a 799 * floating-point value the same as the argument to 800 * {@code doubleToLongBits} (except all NaN values are 801 * collapsed to a single "canonical" NaN value). 802 * 803 * @param value a {@code double} precision floating-point number. 804 * @return the bits that represent the floating-point number. 805 */ 806 public static long doubleToLongBits(double value) { 807 long result = doubleToRawLongBits(value); 808 // Check for NaN based on values of bit fields, maximum 809 // exponent and nonzero significand. 810 if ( ((result & DoubleConsts.EXP_BIT_MASK) == 811 DoubleConsts.EXP_BIT_MASK) && 812 (result & DoubleConsts.SIGNIF_BIT_MASK) != 0L) 813 result = 0x7ff8000000000000L; 814 return result; 815 } 816 817 /** 818 * Returns a representation of the specified floating-point value 819 * according to the IEEE 754 floating-point "double 820 * format" bit layout, preserving Not-a-Number (NaN) values. 821 * 822 * <p>Bit 63 (the bit that is selected by the mask 823 * {@code 0x8000000000000000L}) represents the sign of the 824 * floating-point number. Bits 825 * 62-52 (the bits that are selected by the mask 826 * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0 827 * (the bits that are selected by the mask 828 * {@code 0x000fffffffffffffL}) represent the significand 829 * (sometimes called the mantissa) of the floating-point number. 830 * 831 * <p>If the argument is positive infinity, the result is 832 * {@code 0x7ff0000000000000L}. 833 * 834 * <p>If the argument is negative infinity, the result is 835 * {@code 0xfff0000000000000L}. 836 * 837 * <p>If the argument is NaN, the result is the {@code long} 838 * integer representing the actual NaN value. Unlike the 839 * {@code doubleToLongBits} method, 840 * {@code doubleToRawLongBits} does not collapse all the bit 841 * patterns encoding a NaN to a single "canonical" NaN 842 * value. 843 * 844 * <p>In all cases, the result is a {@code long} integer that, 845 * when given to the {@link #longBitsToDouble(long)} method, will 846 * produce a floating-point value the same as the argument to 847 * {@code doubleToRawLongBits}. 848 * 849 * @param value a {@code double} precision floating-point number. 850 * @return the bits that represent the floating-point number. 851 * @since 1.3 852 */ 853 public static native long doubleToRawLongBits(double value); 854 855 /** 856 * Returns the {@code double} value corresponding to a given 857 * bit representation. 858 * The argument is considered to be a representation of a 859 * floating-point value according to the IEEE 754 floating-point 860 * "double format" bit layout. 861 * 862 * <p>If the argument is {@code 0x7ff0000000000000L}, the result 863 * is positive infinity. 864 * 865 * <p>If the argument is {@code 0xfff0000000000000L}, the result 866 * is negative infinity. 867 * 868 * <p>If the argument is any value in the range 869 * {@code 0x7ff0000000000001L} through 870 * {@code 0x7fffffffffffffffL} or in the range 871 * {@code 0xfff0000000000001L} through 872 * {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE 873 * 754 floating-point operation provided by Java can distinguish 874 * between two NaN values of the same type with different bit 875 * patterns. Distinct values of NaN are only distinguishable by 876 * use of the {@code Double.doubleToRawLongBits} method. 877 * 878 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three 879 * values that can be computed from the argument: 880 * 881 * <blockquote><pre> 882 * int s = ((bits >> 63) == 0) ? 1 : -1; 883 * int e = (int)((bits >> 52) & 0x7ffL); 884 * long m = (e == 0) ? 885 * (bits & 0xfffffffffffffL) << 1 : 886 * (bits & 0xfffffffffffffL) | 0x10000000000000L; 887 * </pre></blockquote> 888 * 889 * Then the floating-point result equals the value of the mathematical 890 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>. 891 * 892 * <p>Note that this method may not be able to return a 893 * {@code double} NaN with exactly same bit pattern as the 894 * {@code long} argument. IEEE 754 distinguishes between two 895 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The 896 * differences between the two kinds of NaN are generally not 897 * visible in Java. Arithmetic operations on signaling NaNs turn 898 * them into quiet NaNs with a different, but often similar, bit 899 * pattern. However, on some processors merely copying a 900 * signaling NaN also performs that conversion. In particular, 901 * copying a signaling NaN to return it to the calling method 902 * may perform this conversion. So {@code longBitsToDouble} 903 * may not be able to return a {@code double} with a 904 * signaling NaN bit pattern. Consequently, for some 905 * {@code long} values, 906 * {@code doubleToRawLongBits(longBitsToDouble(start))} may 907 * <i>not</i> equal {@code start}. Moreover, which 908 * particular bit patterns represent signaling NaNs is platform 909 * dependent; although all NaN bit patterns, quiet or signaling, 910 * must be in the NaN range identified above. 911 * 912 * @param bits any {@code long} integer. 913 * @return the {@code double} floating-point value with the same 914 * bit pattern. 915 */ 916 public static native double longBitsToDouble(long bits); 917 918 /** 919 * Compares two {@code Double} objects numerically. There 920 * are two ways in which comparisons performed by this method 921 * differ from those performed by the Java language numerical 922 * comparison operators ({@code <, <=, ==, >=, >}) 923 * when applied to primitive {@code double} values: 924 * <ul><li> 925 * {@code Double.NaN} is considered by this method 926 * to be equal to itself and greater than all other 927 * {@code double} values (including 928 * {@code Double.POSITIVE_INFINITY}). 929 * <li> 930 * {@code 0.0d} is considered by this method to be greater 931 * than {@code -0.0d}. 932 * </ul> 933 * This ensures that the <i>natural ordering</i> of 934 * {@code Double} objects imposed by this method is <i>consistent 935 * with equals</i>. 936 * 937 * @param anotherDouble the {@code Double} to be compared. 938 * @return the value {@code 0} if {@code anotherDouble} is 939 * numerically equal to this {@code Double}; a value 940 * less than {@code 0} if this {@code Double} 941 * is numerically less than {@code anotherDouble}; 942 * and a value greater than {@code 0} if this 943 * {@code Double} is numerically greater than 944 * {@code anotherDouble}. 945 * 946 * @since 1.2 947 */ 948 public int compareTo(Double anotherDouble) { 949 return Double.compare(value, anotherDouble.value); 950 } 951 952 /** 953 * Compares the two specified {@code double} values. The sign 954 * of the integer value returned is the same as that of the 955 * integer that would be returned by the call: 956 * <pre> 957 * new Double(d1).compareTo(new Double(d2)) 958 * </pre> 959 * 960 * @param d1 the first {@code double} to compare 961 * @param d2 the second {@code double} to compare 962 * @return the value {@code 0} if {@code d1} is 963 * numerically equal to {@code d2}; a value less than 964 * {@code 0} if {@code d1} is numerically less than 965 * {@code d2}; and a value greater than {@code 0} 966 * if {@code d1} is numerically greater than 967 * {@code d2}. 968 * @since 1.4 969 */ 970 public static int compare(double d1, double d2) { 971 if (d1 < d2) 972 return -1; // Neither val is NaN, thisVal is smaller 973 if (d1 > d2) 974 return 1; // Neither val is NaN, thisVal is larger 975 976 long thisBits = Double.doubleToLongBits(d1); 977 long anotherBits = Double.doubleToLongBits(d2); 978 979 return (thisBits == anotherBits ? 0 : // Values are equal 980 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN) 981 1)); // (0.0, -0.0) or (NaN, !NaN) 982 } 983 984 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 985 private static final long serialVersionUID = -9172774392245257468L; 986 }