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 /** 30 * The {@code Long} class wraps a value of the primitive type {@code 31 * long} in an object. An object of type {@code Long} contains a 32 * single field whose type is {@code long}. 33 * 34 * <p> In addition, this class provides several methods for converting 35 * a {@code long} to a {@code String} and a {@code String} to a {@code 36 * long}, as well as other constants and methods useful when dealing 37 * with a {@code long}. 38 * 39 * <p>Implementation note: The implementations of the "bit twiddling" 40 * methods (such as {@link #highestOneBit(long) highestOneBit} and 41 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are 42 * based on material from Henry S. Warren, Jr.'s <i>Hacker's 43 * Delight</i>, (Addison Wesley, 2002). 44 * 45 * @author Lee Boynton 46 * @author Arthur van Hoff 47 * @author Josh Bloch 48 * @author Joseph D. Darcy 49 * @since JDK1.0 50 */ 51 public final class Long extends Number implements Comparable<Long> { 52 /** 53 * A constant holding the minimum value a {@code long} can 54 * have, -2<sup>63</sup>. 55 */ 56 public static final long MIN_VALUE = 0x8000000000000000L; 57 58 /** 59 * A constant holding the maximum value a {@code long} can 60 * have, 2<sup>63</sup>-1. 61 */ 62 public static final long MAX_VALUE = 0x7fffffffffffffffL; 63 64 /** 65 * The {@code Class} instance representing the primitive type 66 * {@code long}. 67 * 68 * @since JDK1.1 69 */ 70 public static final Class<Long> TYPE = (Class<Long>) long[].class.getComponentType(); 71 72 /** 73 * Returns a string representation of the first argument in the 74 * radix specified by the second argument. 75 * 76 * <p>If the radix is smaller than {@code Character.MIN_RADIX} 77 * or larger than {@code Character.MAX_RADIX}, then the radix 78 * {@code 10} is used instead. 79 * 80 * <p>If the first argument is negative, the first element of the 81 * result is the ASCII minus sign {@code '-'} 82 * (<code>'\u002d'</code>). If the first argument is not 83 * negative, no sign character appears in the result. 84 * 85 * <p>The remaining characters of the result represent the magnitude 86 * of the first argument. If the magnitude is zero, it is 87 * represented by a single zero character {@code '0'} 88 * (<code>'\u0030'</code>); otherwise, the first character of 89 * the representation of the magnitude will not be the zero 90 * character. The following ASCII characters are used as digits: 91 * 92 * <blockquote> 93 * {@code 0123456789abcdefghijklmnopqrstuvwxyz} 94 * </blockquote> 95 * 96 * These are <code>'\u0030'</code> through 97 * <code>'\u0039'</code> and <code>'\u0061'</code> through 98 * <code>'\u007a'</code>. If {@code radix} is 99 * <var>N</var>, then the first <var>N</var> of these characters 100 * are used as radix-<var>N</var> digits in the order shown. Thus, 101 * the digits for hexadecimal (radix 16) are 102 * {@code 0123456789abcdef}. If uppercase letters are 103 * desired, the {@link java.lang.String#toUpperCase()} method may 104 * be called on the result: 105 * 106 * <blockquote> 107 * {@code Long.toString(n, 16).toUpperCase()} 108 * </blockquote> 109 * 110 * @param i a {@code long} to be converted to a string. 111 * @param radix the radix to use in the string representation. 112 * @return a string representation of the argument in the specified radix. 113 * @see java.lang.Character#MAX_RADIX 114 * @see java.lang.Character#MIN_RADIX 115 */ toString(long i, int radix)116 public static String toString(long i, int radix) { 117 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) 118 radix = 10; 119 if (radix == 10) 120 return toString(i); 121 char[] buf = new char[65]; 122 int charPos = 64; 123 boolean negative = (i < 0); 124 125 if (!negative) { 126 i = -i; 127 } 128 129 while (i <= -radix) { 130 buf[charPos--] = Integer.digits[(int)(-(i % radix))]; 131 i = i / radix; 132 } 133 buf[charPos] = Integer.digits[(int)(-i)]; 134 135 if (negative) { 136 buf[--charPos] = '-'; 137 } 138 139 return new String(buf, charPos, (65 - charPos)); 140 } 141 142 /** 143 * Returns a string representation of the {@code long} 144 * argument as an unsigned integer in base 16. 145 * 146 * <p>The unsigned {@code long} value is the argument plus 147 * 2<sup>64</sup> if the argument is negative; otherwise, it is 148 * equal to the argument. This value is converted to a string of 149 * ASCII digits in hexadecimal (base 16) with no extra 150 * leading {@code 0}s. If the unsigned magnitude is zero, it 151 * is represented by a single zero character {@code '0'} 152 * (<code>'\u0030'</code>); otherwise, the first character of 153 * the representation of the unsigned magnitude will not be the 154 * zero character. The following characters are used as 155 * hexadecimal digits: 156 * 157 * <blockquote> 158 * {@code 0123456789abcdef} 159 * </blockquote> 160 * 161 * These are the characters <code>'\u0030'</code> through 162 * <code>'\u0039'</code> and <code>'\u0061'</code> through 163 * <code>'\u0066'</code>. If uppercase letters are desired, 164 * the {@link java.lang.String#toUpperCase()} method may be called 165 * on the result: 166 * 167 * <blockquote> 168 * {@code Long.toHexString(n).toUpperCase()} 169 * </blockquote> 170 * 171 * @param i a {@code long} to be converted to a string. 172 * @return the string representation of the unsigned {@code long} 173 * value represented by the argument in hexadecimal 174 * (base 16). 175 * @since JDK 1.0.2 176 */ toHexString(long i)177 public static String toHexString(long i) { 178 return toUnsignedString(i, 4); 179 } 180 181 /** 182 * Returns a string representation of the {@code long} 183 * argument as an unsigned integer in base 8. 184 * 185 * <p>The unsigned {@code long} value is the argument plus 186 * 2<sup>64</sup> if the argument is negative; otherwise, it is 187 * equal to the argument. This value is converted to a string of 188 * ASCII digits in octal (base 8) with no extra leading 189 * {@code 0}s. 190 * 191 * <p>If the unsigned magnitude is zero, it is represented by a 192 * single zero character {@code '0'} 193 * (<code>'\u0030'</code>); otherwise, the first character of 194 * the representation of the unsigned magnitude will not be the 195 * zero character. The following characters are used as octal 196 * digits: 197 * 198 * <blockquote> 199 * {@code 01234567} 200 * </blockquote> 201 * 202 * These are the characters <code>'\u0030'</code> through 203 * <code>'\u0037'</code>. 204 * 205 * @param i a {@code long} to be converted to a string. 206 * @return the string representation of the unsigned {@code long} 207 * value represented by the argument in octal (base 8). 208 * @since JDK 1.0.2 209 */ toOctalString(long i)210 public static String toOctalString(long i) { 211 return toUnsignedString(i, 3); 212 } 213 214 /** 215 * Returns a string representation of the {@code long} 216 * argument as an unsigned integer in base 2. 217 * 218 * <p>The unsigned {@code long} value is the argument plus 219 * 2<sup>64</sup> if the argument is negative; otherwise, it is 220 * equal to the argument. This value is converted to a string of 221 * ASCII digits in binary (base 2) with no extra leading 222 * {@code 0}s. If the unsigned magnitude is zero, it is 223 * represented by a single zero character {@code '0'} 224 * (<code>'\u0030'</code>); otherwise, the first character of 225 * the representation of the unsigned magnitude will not be the 226 * zero character. The characters {@code '0'} 227 * (<code>'\u0030'</code>) and {@code '1'} 228 * (<code>'\u0031'</code>) are used as binary digits. 229 * 230 * @param i a {@code long} to be converted to a string. 231 * @return the string representation of the unsigned {@code long} 232 * value represented by the argument in binary (base 2). 233 * @since JDK 1.0.2 234 */ toBinaryString(long i)235 public static String toBinaryString(long i) { 236 return toUnsignedString(i, 1); 237 } 238 239 /** 240 * Convert the integer to an unsigned number. 241 */ toUnsignedString(long i, int shift)242 private static String toUnsignedString(long i, int shift) { 243 char[] buf = new char[64]; 244 int charPos = 64; 245 int radix = 1 << shift; 246 long mask = radix - 1; 247 do { 248 buf[--charPos] = Integer.digits[(int)(i & mask)]; 249 i >>>= shift; 250 } while (i != 0); 251 return new String(buf, charPos, (64 - charPos)); 252 } 253 254 /** 255 * Returns a {@code String} object representing the specified 256 * {@code long}. The argument is converted to signed decimal 257 * representation and returned as a string, exactly as if the 258 * argument and the radix 10 were given as arguments to the {@link 259 * #toString(long, int)} method. 260 * 261 * @param i a {@code long} to be converted. 262 * @return a string representation of the argument in base 10. 263 */ toString(long i)264 public static String toString(long i) { 265 if (i == Long.MIN_VALUE) 266 return "-9223372036854775808"; 267 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i); 268 char[] buf = new char[size]; 269 getChars(i, size, buf); 270 // Android-changed: change string constructor. 271 return new String(buf); 272 } 273 274 /** 275 * Places characters representing the integer i into the 276 * character array buf. The characters are placed into 277 * the buffer backwards starting with the least significant 278 * digit at the specified index (exclusive), and working 279 * backwards from there. 280 * 281 * Will fail if i == Long.MIN_VALUE 282 */ getChars(long i, int index, char[] buf)283 static void getChars(long i, int index, char[] buf) { 284 long q; 285 int r; 286 int charPos = index; 287 char sign = 0; 288 289 if (i < 0) { 290 sign = '-'; 291 i = -i; 292 } 293 294 // Get 2 digits/iteration using longs until quotient fits into an int 295 while (i > Integer.MAX_VALUE) { 296 q = i / 100; 297 // really: r = i - (q * 100); 298 r = (int)(i - ((q << 6) + (q << 5) + (q << 2))); 299 i = q; 300 buf[--charPos] = Integer.DigitOnes[r]; 301 buf[--charPos] = Integer.DigitTens[r]; 302 } 303 304 // Get 2 digits/iteration using ints 305 int q2; 306 int i2 = (int)i; 307 while (i2 >= 65536) { 308 q2 = i2 / 100; 309 // really: r = i2 - (q * 100); 310 r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2)); 311 i2 = q2; 312 buf[--charPos] = Integer.DigitOnes[r]; 313 buf[--charPos] = Integer.DigitTens[r]; 314 } 315 316 // Fall thru to fast mode for smaller numbers 317 // assert(i2 <= 65536, i2); 318 for (;;) { 319 q2 = (i2 * 52429) >>> (16+3); 320 r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ... 321 buf[--charPos] = Integer.digits[r]; 322 i2 = q2; 323 if (i2 == 0) break; 324 } 325 if (sign != 0) { 326 buf[--charPos] = sign; 327 } 328 } 329 330 // Requires positive x stringSize(long x)331 static int stringSize(long x) { 332 long p = 10; 333 for (int i=1; i<19; i++) { 334 if (x < p) 335 return i; 336 p = 10*p; 337 } 338 return 19; 339 } 340 341 /** 342 * Parses the string argument as a signed {@code long} in the 343 * radix specified by the second argument. The characters in the 344 * string must all be digits of the specified radix (as determined 345 * by whether {@link java.lang.Character#digit(char, int)} returns 346 * a nonnegative value), except that the first character may be an 347 * ASCII minus sign {@code '-'} (<code>'\u002D'</code>) to 348 * indicate a negative value or an ASCII plus sign {@code '+'} 349 * (<code>'\u002B'</code>) to indicate a positive value. The 350 * resulting {@code long} value is returned. 351 * 352 * <p>Note that neither the character {@code L} 353 * (<code>'\u004C'</code>) nor {@code l} 354 * (<code>'\u006C'</code>) is permitted to appear at the end 355 * of the string as a type indicator, as would be permitted in 356 * Java programming language source code - except that either 357 * {@code L} or {@code l} may appear as a digit for a 358 * radix greater than 22. 359 * 360 * <p>An exception of type {@code NumberFormatException} is 361 * thrown if any of the following situations occurs: 362 * <ul> 363 * 364 * <li>The first argument is {@code null} or is a string of 365 * length zero. 366 * 367 * <li>The {@code radix} is either smaller than {@link 368 * java.lang.Character#MIN_RADIX} or larger than {@link 369 * java.lang.Character#MAX_RADIX}. 370 * 371 * <li>Any character of the string is not a digit of the specified 372 * radix, except that the first character may be a minus sign 373 * {@code '-'} (<code>'\u002d'</code>) or plus sign {@code 374 * '+'} (<code>'\u002B'</code>) provided that the string is 375 * longer than length 1. 376 * 377 * <li>The value represented by the string is not a value of type 378 * {@code long}. 379 * </ul> 380 * 381 * <p>Examples: 382 * <blockquote><pre> 383 * parseLong("0", 10) returns 0L 384 * parseLong("473", 10) returns 473L 385 * parseLong("+42", 10) returns 42L 386 * parseLong("-0", 10) returns 0L 387 * parseLong("-FF", 16) returns -255L 388 * parseLong("1100110", 2) returns 102L 389 * parseLong("99", 8) throws a NumberFormatException 390 * parseLong("Hazelnut", 10) throws a NumberFormatException 391 * parseLong("Hazelnut", 36) returns 1356099454469L 392 * </pre></blockquote> 393 * 394 * @param s the {@code String} containing the 395 * {@code long} representation to be parsed. 396 * @param radix the radix to be used while parsing {@code s}. 397 * @return the {@code long} represented by the string argument in 398 * the specified radix. 399 * @throws NumberFormatException if the string does not contain a 400 * parsable {@code long}. 401 */ parseLong(String s, int radix)402 public static long parseLong(String s, int radix) 403 throws NumberFormatException 404 { 405 if (s == null) { 406 throw new NumberFormatException("null"); 407 } 408 409 if (radix < Character.MIN_RADIX) { 410 throw new NumberFormatException("radix " + radix + 411 " less than Character.MIN_RADIX"); 412 } 413 if (radix > Character.MAX_RADIX) { 414 throw new NumberFormatException("radix " + radix + 415 " greater than Character.MAX_RADIX"); 416 } 417 418 long result = 0; 419 boolean negative = false; 420 int i = 0, len = s.length(); 421 long limit = -Long.MAX_VALUE; 422 long multmin; 423 int digit; 424 425 if (len > 0) { 426 char firstChar = s.charAt(0); 427 if (firstChar < '0') { // Possible leading "+" or "-" 428 if (firstChar == '-') { 429 negative = true; 430 limit = Long.MIN_VALUE; 431 } else if (firstChar != '+') 432 throw NumberFormatException.forInputString(s); 433 434 if (len == 1) // Cannot have lone "+" or "-" 435 throw NumberFormatException.forInputString(s); 436 i++; 437 } 438 multmin = limit / radix; 439 while (i < len) { 440 // Accumulating negatively avoids surprises near MAX_VALUE 441 digit = Character.digit(s.charAt(i++),radix); 442 if (digit < 0) { 443 throw NumberFormatException.forInputString(s); 444 } 445 if (result < multmin) { 446 throw NumberFormatException.forInputString(s); 447 } 448 result *= radix; 449 if (result < limit + digit) { 450 throw NumberFormatException.forInputString(s); 451 } 452 result -= digit; 453 } 454 } else { 455 throw NumberFormatException.forInputString(s); 456 } 457 return negative ? result : -result; 458 } 459 460 /** 461 * Parses the string argument as a signed decimal {@code long}. 462 * The characters in the string must all be decimal digits, except 463 * that the first character may be an ASCII minus sign {@code '-'} 464 * (<code>\u002D'</code>) to indicate a negative value or an 465 * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to 466 * indicate a positive value. The resulting {@code long} value is 467 * returned, exactly as if the argument and the radix {@code 10} 468 * were given as arguments to the {@link 469 * #parseLong(java.lang.String, int)} method. 470 * 471 * <p>Note that neither the character {@code L} 472 * (<code>'\u004C'</code>) nor {@code l} 473 * (<code>'\u006C'</code>) is permitted to appear at the end 474 * of the string as a type indicator, as would be permitted in 475 * Java programming language source code. 476 * 477 * @param s a {@code String} containing the {@code long} 478 * representation to be parsed 479 * @return the {@code long} represented by the argument in 480 * decimal. 481 * @throws NumberFormatException if the string does not contain a 482 * parsable {@code long}. 483 */ parseLong(String s)484 public static long parseLong(String s) throws NumberFormatException { 485 return parseLong(s, 10); 486 } 487 488 /** 489 * Returns a {@code Long} object holding the value 490 * extracted from the specified {@code String} when parsed 491 * with the radix given by the second argument. The first 492 * argument is interpreted as representing a signed 493 * {@code long} in the radix specified by the second 494 * argument, exactly as if the arguments were given to the {@link 495 * #parseLong(java.lang.String, int)} method. The result is a 496 * {@code Long} object that represents the {@code long} 497 * value specified by the string. 498 * 499 * <p>In other words, this method returns a {@code Long} object equal 500 * to the value of: 501 * 502 * <blockquote> 503 * {@code new Long(Long.parseLong(s, radix))} 504 * </blockquote> 505 * 506 * @param s the string to be parsed 507 * @param radix the radix to be used in interpreting {@code s} 508 * @return a {@code Long} object holding the value 509 * represented by the string argument in the specified 510 * radix. 511 * @throws NumberFormatException If the {@code String} does not 512 * contain a parsable {@code long}. 513 */ valueOf(String s, int radix)514 public static Long valueOf(String s, int radix) throws NumberFormatException { 515 return Long.valueOf(parseLong(s, radix)); 516 } 517 518 /** 519 * Returns a {@code Long} object holding the value 520 * of the specified {@code String}. The argument is 521 * interpreted as representing a signed decimal {@code long}, 522 * exactly as if the argument were given to the {@link 523 * #parseLong(java.lang.String)} method. The result is a 524 * {@code Long} object that represents the integer value 525 * specified by the string. 526 * 527 * <p>In other words, this method returns a {@code Long} object 528 * equal to the value of: 529 * 530 * <blockquote> 531 * {@code new Long(Long.parseLong(s))} 532 * </blockquote> 533 * 534 * @param s the string to be parsed. 535 * @return a {@code Long} object holding the value 536 * represented by the string argument. 537 * @throws NumberFormatException If the string cannot be parsed 538 * as a {@code long}. 539 */ valueOf(String s)540 public static Long valueOf(String s) throws NumberFormatException 541 { 542 return Long.valueOf(parseLong(s, 10)); 543 } 544 545 private static class LongCache { LongCache()546 private LongCache(){} 547 548 static final Long cache[] = new Long[-(-128) + 127 + 1]; 549 550 static { 551 for(int i = 0; i < cache.length; i++) 552 cache[i] = new Long(i - 128); 553 } 554 } 555 556 /** 557 * Returns a {@code Long} instance representing the specified 558 * {@code long} value. 559 * If a new {@code Long} instance is not required, this method 560 * should generally be used in preference to the constructor 561 * {@link #Long(long)}, as this method is likely to yield 562 * significantly better space and time performance by caching 563 * frequently requested values. 564 * 565 * Note that unlike the {@linkplain Integer#valueOf(int) 566 * corresponding method} in the {@code Integer} class, this method 567 * is <em>not</em> required to cache values within a particular 568 * range. 569 * 570 * @param l a long value. 571 * @return a {@code Long} instance representing {@code l}. 572 * @since 1.5 573 */ valueOf(long l)574 public static Long valueOf(long l) { 575 final int offset = 128; 576 if (l >= -128 && l <= 127) { // will cache 577 return LongCache.cache[(int)l + offset]; 578 } 579 return new Long(l); 580 } 581 582 /** 583 * Decodes a {@code String} into a {@code Long}. 584 * Accepts decimal, hexadecimal, and octal numbers given by the 585 * following grammar: 586 * 587 * <blockquote> 588 * <dl> 589 * <dt><i>DecodableString:</i> 590 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> 591 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> 592 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> 593 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> 594 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> 595 * <p> 596 * <dt><i>Sign:</i> 597 * <dd>{@code -} 598 * <dd>{@code +} 599 * </dl> 600 * </blockquote> 601 * 602 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> 603 * are as defined in section 3.10.1 of 604 * <cite>The Java™ Language Specification</cite>, 605 * except that underscores are not accepted between digits. 606 * 607 * <p>The sequence of characters following an optional 608 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", 609 * "{@code #}", or leading zero) is parsed as by the {@code 610 * Long.parseLong} method with the indicated radix (10, 16, or 8). 611 * This sequence of characters must represent a positive value or 612 * a {@link NumberFormatException} will be thrown. The result is 613 * negated if first character of the specified {@code String} is 614 * the minus sign. No whitespace characters are permitted in the 615 * {@code String}. 616 * 617 * @param nm the {@code String} to decode. 618 * @return a {@code Long} object holding the {@code long} 619 * value represented by {@code nm} 620 * @throws NumberFormatException if the {@code String} does not 621 * contain a parsable {@code long}. 622 * @see java.lang.Long#parseLong(String, int) 623 * @since 1.2 624 */ decode(String nm)625 public static Long decode(String nm) throws NumberFormatException { 626 int radix = 10; 627 int index = 0; 628 boolean negative = false; 629 Long result; 630 631 if (nm.length() == 0) 632 throw new NumberFormatException("Zero length string"); 633 char firstChar = nm.charAt(0); 634 // Handle sign, if present 635 if (firstChar == '-') { 636 negative = true; 637 index++; 638 } else if (firstChar == '+') 639 index++; 640 641 // Handle radix specifier, if present 642 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) { 643 index += 2; 644 radix = 16; 645 } 646 else if (nm.startsWith("#", index)) { 647 index ++; 648 radix = 16; 649 } 650 else if (nm.startsWith("0", index) && nm.length() > 1 + index) { 651 index ++; 652 radix = 8; 653 } 654 655 if (nm.startsWith("-", index) || nm.startsWith("+", index)) 656 throw new NumberFormatException("Sign character in wrong position"); 657 658 try { 659 result = Long.valueOf(nm.substring(index), radix); 660 result = negative ? Long.valueOf(-result.longValue()) : result; 661 } catch (NumberFormatException e) { 662 // If number is Long.MIN_VALUE, we'll end up here. The next line 663 // handles this case, and causes any genuine format error to be 664 // rethrown. 665 String constant = negative ? ("-" + nm.substring(index)) 666 : nm.substring(index); 667 result = Long.valueOf(constant, radix); 668 } 669 return result; 670 } 671 672 /** 673 * The value of the {@code Long}. 674 * 675 * @serial 676 */ 677 private final long value; 678 679 /** 680 * Constructs a newly allocated {@code Long} object that 681 * represents the specified {@code long} argument. 682 * 683 * @param value the value to be represented by the 684 * {@code Long} object. 685 */ Long(long value)686 public Long(long value) { 687 this.value = value; 688 } 689 690 /** 691 * Constructs a newly allocated {@code Long} object that 692 * represents the {@code long} value indicated by the 693 * {@code String} parameter. The string is converted to a 694 * {@code long} value in exactly the manner used by the 695 * {@code parseLong} method for radix 10. 696 * 697 * @param s the {@code String} to be converted to a 698 * {@code Long}. 699 * @throws NumberFormatException if the {@code String} does not 700 * contain a parsable {@code long}. 701 * @see java.lang.Long#parseLong(java.lang.String, int) 702 */ Long(String s)703 public Long(String s) throws NumberFormatException { 704 this.value = parseLong(s, 10); 705 } 706 707 /** 708 * Returns the value of this {@code Long} as a 709 * {@code byte}. 710 */ byteValue()711 public byte byteValue() { 712 return (byte)value; 713 } 714 715 /** 716 * Returns the value of this {@code Long} as a 717 * {@code short}. 718 */ shortValue()719 public short shortValue() { 720 return (short)value; 721 } 722 723 /** 724 * Returns the value of this {@code Long} as an 725 * {@code int}. 726 */ intValue()727 public int intValue() { 728 return (int)value; 729 } 730 731 /** 732 * Returns the value of this {@code Long} as a 733 * {@code long} value. 734 */ longValue()735 public long longValue() { 736 return (long)value; 737 } 738 739 /** 740 * Returns the value of this {@code Long} as a 741 * {@code float}. 742 */ floatValue()743 public float floatValue() { 744 return (float)value; 745 } 746 747 /** 748 * Returns the value of this {@code Long} as a 749 * {@code double}. 750 */ doubleValue()751 public double doubleValue() { 752 return (double)value; 753 } 754 755 /** 756 * Returns a {@code String} object representing this 757 * {@code Long}'s value. The value is converted to signed 758 * decimal representation and returned as a string, exactly as if 759 * the {@code long} value were given as an argument to the 760 * {@link java.lang.Long#toString(long)} method. 761 * 762 * @return a string representation of the value of this object in 763 * base 10. 764 */ toString()765 public String toString() { 766 return toString(value); 767 } 768 769 /** 770 * Returns a hash code for this {@code Long}. The result is 771 * the exclusive OR of the two halves of the primitive 772 * {@code long} value held by this {@code Long} 773 * object. That is, the hashcode is the value of the expression: 774 * 775 * <blockquote> 776 * {@code (int)(this.longValue()^(this.longValue()>>>32))} 777 * </blockquote> 778 * 779 * @return a hash code value for this object. 780 */ hashCode()781 public int hashCode() { 782 return Long.hashCode(value); 783 } 784 785 /** 786 * Returns a hash code for a {@code long} value; compatible with 787 * {@code Long.hashCode()}. 788 * 789 * @param value the value to hash 790 * @return a hash code value for a {@code long} value. 791 * @since 1.8 792 */ hashCode(long value)793 public static int hashCode(long value) { 794 return (int)(value ^ (value >>> 32)); 795 } 796 797 /** 798 * Compares this object to the specified object. The result is 799 * {@code true} if and only if the argument is not 800 * {@code null} and is a {@code Long} object that 801 * contains the same {@code long} value as this object. 802 * 803 * @param obj the object to compare with. 804 * @return {@code true} if the objects are the same; 805 * {@code false} otherwise. 806 */ equals(Object obj)807 public boolean equals(Object obj) { 808 if (obj instanceof Long) { 809 return value == ((Long)obj).longValue(); 810 } 811 return false; 812 } 813 814 /** 815 * Determines the {@code long} value of the system property 816 * with the specified name. 817 * 818 * <p>The first argument is treated as the name of a system property. 819 * System properties are accessible through the {@link 820 * java.lang.System#getProperty(java.lang.String)} method. The 821 * string value of this property is then interpreted as a 822 * {@code long} value and a {@code Long} object 823 * representing this value is returned. Details of possible 824 * numeric formats can be found with the definition of 825 * {@code getProperty}. 826 * 827 * <p>If there is no property with the specified name, if the 828 * specified name is empty or {@code null}, or if the 829 * property does not have the correct numeric format, then 830 * {@code null} is returned. 831 * 832 * <p>In other words, this method returns a {@code Long} object equal to 833 * the value of: 834 * 835 * <blockquote> 836 * {@code getLong(nm, null)} 837 * </blockquote> 838 * 839 * @param nm property name. 840 * @return the {@code Long} value of the property. 841 * @see java.lang.System#getProperty(java.lang.String) 842 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 843 */ getLong(String nm)844 public static Long getLong(String nm) { 845 return getLong(nm, null); 846 } 847 848 /** 849 * Determines the {@code long} value of the system property 850 * with the specified name. 851 * 852 * <p>The first argument is treated as the name of a system property. 853 * System properties are accessible through the {@link 854 * java.lang.System#getProperty(java.lang.String)} method. The 855 * string value of this property is then interpreted as a 856 * {@code long} value and a {@code Long} object 857 * representing this value is returned. Details of possible 858 * numeric formats can be found with the definition of 859 * {@code getProperty}. 860 * 861 * <p>The second argument is the default value. A {@code Long} object 862 * that represents the value of the second argument is returned if there 863 * is no property of the specified name, if the property does not have 864 * the correct numeric format, or if the specified name is empty or null. 865 * 866 * <p>In other words, this method returns a {@code Long} object equal 867 * to the value of: 868 * 869 * <blockquote> 870 * {@code getLong(nm, new Long(val))} 871 * </blockquote> 872 * 873 * but in practice it may be implemented in a manner such as: 874 * 875 * <blockquote><pre> 876 * Long result = getLong(nm, null); 877 * return (result == null) ? new Long(val) : result; 878 * </pre></blockquote> 879 * 880 * to avoid the unnecessary allocation of a {@code Long} object when 881 * the default value is not needed. 882 * 883 * @param nm property name. 884 * @param val default value. 885 * @return the {@code Long} value of the property. 886 * @see java.lang.System#getProperty(java.lang.String) 887 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 888 */ getLong(String nm, long val)889 public static Long getLong(String nm, long val) { 890 Long result = Long.getLong(nm, null); 891 return (result == null) ? Long.valueOf(val) : result; 892 } 893 894 /** 895 * Returns the {@code long} value of the system property with 896 * the specified name. The first argument is treated as the name 897 * of a system property. System properties are accessible through 898 * the {@link java.lang.System#getProperty(java.lang.String)} 899 * method. The string value of this property is then interpreted 900 * as a {@code long} value, as per the 901 * {@code Long.decode} method, and a {@code Long} object 902 * representing this value is returned. 903 * 904 * <ul> 905 * <li>If the property value begins with the two ASCII characters 906 * {@code 0x} or the ASCII character {@code #}, not followed by 907 * a minus sign, then the rest of it is parsed as a hexadecimal integer 908 * exactly as for the method {@link #valueOf(java.lang.String, int)} 909 * with radix 16. 910 * <li>If the property value begins with the ASCII character 911 * {@code 0} followed by another character, it is parsed as 912 * an octal integer exactly as by the method {@link 913 * #valueOf(java.lang.String, int)} with radix 8. 914 * <li>Otherwise the property value is parsed as a decimal 915 * integer exactly as by the method 916 * {@link #valueOf(java.lang.String, int)} with radix 10. 917 * </ul> 918 * 919 * <p>Note that, in every case, neither {@code L} 920 * (<code>'\u004C'</code>) nor {@code l} 921 * (<code>'\u006C'</code>) is permitted to appear at the end 922 * of the property value as a type indicator, as would be 923 * permitted in Java programming language source code. 924 * 925 * <p>The second argument is the default value. The default value is 926 * returned if there is no property of the specified name, if the 927 * property does not have the correct numeric format, or if the 928 * specified name is empty or {@code null}. 929 * 930 * @param nm property name. 931 * @param val default value. 932 * @return the {@code Long} value of the property. 933 * @see java.lang.System#getProperty(java.lang.String) 934 * @see java.lang.System#getProperty(java.lang.String, java.lang.String) 935 * @see java.lang.Long#decode 936 */ getLong(String nm, Long val)937 public static Long getLong(String nm, Long val) { 938 String v = null; 939 try { 940 v = System.getProperty(nm); 941 } catch (IllegalArgumentException e) { 942 } catch (NullPointerException e) { 943 } 944 if (v != null) { 945 try { 946 return Long.decode(v); 947 } catch (NumberFormatException e) { 948 } 949 } 950 return val; 951 } 952 953 /** 954 * Compares two {@code Long} objects numerically. 955 * 956 * @param anotherLong the {@code Long} to be compared. 957 * @return the value {@code 0} if this {@code Long} is 958 * equal to the argument {@code Long}; a value less than 959 * {@code 0} if this {@code Long} is numerically less 960 * than the argument {@code Long}; and a value greater 961 * than {@code 0} if this {@code Long} is numerically 962 * greater than the argument {@code Long} (signed 963 * comparison). 964 * @since 1.2 965 */ compareTo(Long anotherLong)966 public int compareTo(Long anotherLong) { 967 return compare(this.value, anotherLong.value); 968 } 969 970 /** 971 * Compares two {@code long} values numerically. 972 * The value returned is identical to what would be returned by: 973 * <pre> 974 * Long.valueOf(x).compareTo(Long.valueOf(y)) 975 * </pre> 976 * 977 * @param x the first {@code long} to compare 978 * @param y the second {@code long} to compare 979 * @return the value {@code 0} if {@code x == y}; 980 * a value less than {@code 0} if {@code x < y}; and 981 * a value greater than {@code 0} if {@code x > y} 982 * @since 1.7 983 */ compare(long x, long y)984 public static int compare(long x, long y) { 985 return (x < y) ? -1 : ((x == y) ? 0 : 1); 986 } 987 988 989 // Bit Twiddling 990 991 /** 992 * The number of bits used to represent a {@code long} value in two's 993 * complement binary form. 994 * 995 * @since 1.5 996 */ 997 public static final int SIZE = 64; 998 999 /** 1000 * The number of bytes used to represent a {@code long} value in two's 1001 * complement binary form. 1002 * 1003 * @since 1.8 1004 */ 1005 public static final int BYTES = SIZE / Byte.SIZE; 1006 1007 /** 1008 * Returns a {@code long} value with at most a single one-bit, in the 1009 * position of the highest-order ("leftmost") one-bit in the specified 1010 * {@code long} value. Returns zero if the specified value has no 1011 * one-bits in its two's complement binary representation, that is, if it 1012 * is equal to zero. 1013 * 1014 * @return a {@code long} value with a single one-bit, in the position 1015 * of the highest-order one-bit in the specified value, or zero if 1016 * the specified value is itself equal to zero. 1017 * @since 1.5 1018 */ highestOneBit(long i)1019 public static long highestOneBit(long i) { 1020 // HD, Figure 3-1 1021 i |= (i >> 1); 1022 i |= (i >> 2); 1023 i |= (i >> 4); 1024 i |= (i >> 8); 1025 i |= (i >> 16); 1026 i |= (i >> 32); 1027 return i - (i >>> 1); 1028 } 1029 1030 /** 1031 * Returns a {@code long} value with at most a single one-bit, in the 1032 * position of the lowest-order ("rightmost") one-bit in the specified 1033 * {@code long} value. Returns zero if the specified value has no 1034 * one-bits in its two's complement binary representation, that is, if it 1035 * is equal to zero. 1036 * 1037 * @return a {@code long} value with a single one-bit, in the position 1038 * of the lowest-order one-bit in the specified value, or zero if 1039 * the specified value is itself equal to zero. 1040 * @since 1.5 1041 */ lowestOneBit(long i)1042 public static long lowestOneBit(long i) { 1043 // HD, Section 2-1 1044 return i & -i; 1045 } 1046 1047 /** 1048 * Returns the number of zero bits preceding the highest-order 1049 * ("leftmost") one-bit in the two's complement binary representation 1050 * of the specified {@code long} value. Returns 64 if the 1051 * specified value has no one-bits in its two's complement representation, 1052 * in other words if it is equal to zero. 1053 * 1054 * <p>Note that this method is closely related to the logarithm base 2. 1055 * For all positive {@code long} values x: 1056 * <ul> 1057 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)} 1058 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)} 1059 * </ul> 1060 * 1061 * @return the number of zero bits preceding the highest-order 1062 * ("leftmost") one-bit in the two's complement binary representation 1063 * of the specified {@code long} value, or 64 if the value 1064 * is equal to zero. 1065 * @since 1.5 1066 */ numberOfLeadingZeros(long i)1067 public static int numberOfLeadingZeros(long i) { 1068 // HD, Figure 5-6 1069 if (i == 0) 1070 return 64; 1071 int n = 1; 1072 int x = (int)(i >>> 32); 1073 if (x == 0) { n += 32; x = (int)i; } 1074 if (x >>> 16 == 0) { n += 16; x <<= 16; } 1075 if (x >>> 24 == 0) { n += 8; x <<= 8; } 1076 if (x >>> 28 == 0) { n += 4; x <<= 4; } 1077 if (x >>> 30 == 0) { n += 2; x <<= 2; } 1078 n -= x >>> 31; 1079 return n; 1080 } 1081 1082 /** 1083 * Returns the number of zero bits following the lowest-order ("rightmost") 1084 * one-bit in the two's complement binary representation of the specified 1085 * {@code long} value. Returns 64 if the specified value has no 1086 * one-bits in its two's complement representation, in other words if it is 1087 * equal to zero. 1088 * 1089 * @return the number of zero bits following the lowest-order ("rightmost") 1090 * one-bit in the two's complement binary representation of the 1091 * specified {@code long} value, or 64 if the value is equal 1092 * to zero. 1093 * @since 1.5 1094 */ numberOfTrailingZeros(long i)1095 public static int numberOfTrailingZeros(long i) { 1096 // HD, Figure 5-14 1097 int x, y; 1098 if (i == 0) return 64; 1099 int n = 63; 1100 y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32); 1101 y = x <<16; if (y != 0) { n = n -16; x = y; } 1102 y = x << 8; if (y != 0) { n = n - 8; x = y; } 1103 y = x << 4; if (y != 0) { n = n - 4; x = y; } 1104 y = x << 2; if (y != 0) { n = n - 2; x = y; } 1105 return n - ((x << 1) >>> 31); 1106 } 1107 1108 /** 1109 * Returns the number of one-bits in the two's complement binary 1110 * representation of the specified {@code long} value. This function is 1111 * sometimes referred to as the <i>population count</i>. 1112 * 1113 * @return the number of one-bits in the two's complement binary 1114 * representation of the specified {@code long} value. 1115 * @since 1.5 1116 */ bitCount(long i)1117 public static int bitCount(long i) { 1118 // HD, Figure 5-14 1119 i = i - ((i >>> 1) & 0x5555555555555555L); 1120 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L); 1121 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL; 1122 i = i + (i >>> 8); 1123 i = i + (i >>> 16); 1124 i = i + (i >>> 32); 1125 return (int)i & 0x7f; 1126 } 1127 1128 /** 1129 * Returns the value obtained by rotating the two's complement binary 1130 * representation of the specified {@code long} value left by the 1131 * specified number of bits. (Bits shifted out of the left hand, or 1132 * high-order, side reenter on the right, or low-order.) 1133 * 1134 * <p>Note that left rotation with a negative distance is equivalent to 1135 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val, 1136 * distance)}. Note also that rotation by any multiple of 64 is a 1137 * no-op, so all but the last six bits of the rotation distance can be 1138 * ignored, even if the distance is negative: {@code rotateLeft(val, 1139 * distance) == rotateLeft(val, distance & 0x3F)}. 1140 * 1141 * @return the value obtained by rotating the two's complement binary 1142 * representation of the specified {@code long} value left by the 1143 * specified number of bits. 1144 * @since 1.5 1145 */ rotateLeft(long i, int distance)1146 public static long rotateLeft(long i, int distance) { 1147 return (i << distance) | (i >>> -distance); 1148 } 1149 1150 /** 1151 * Returns the value obtained by rotating the two's complement binary 1152 * representation of the specified {@code long} value right by the 1153 * specified number of bits. (Bits shifted out of the right hand, or 1154 * low-order, side reenter on the left, or high-order.) 1155 * 1156 * <p>Note that right rotation with a negative distance is equivalent to 1157 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val, 1158 * distance)}. Note also that rotation by any multiple of 64 is a 1159 * no-op, so all but the last six bits of the rotation distance can be 1160 * ignored, even if the distance is negative: {@code rotateRight(val, 1161 * distance) == rotateRight(val, distance & 0x3F)}. 1162 * 1163 * @return the value obtained by rotating the two's complement binary 1164 * representation of the specified {@code long} value right by the 1165 * specified number of bits. 1166 * @since 1.5 1167 */ rotateRight(long i, int distance)1168 public static long rotateRight(long i, int distance) { 1169 return (i >>> distance) | (i << -distance); 1170 } 1171 1172 /** 1173 * Returns the value obtained by reversing the order of the bits in the 1174 * two's complement binary representation of the specified {@code long} 1175 * value. 1176 * 1177 * @return the value obtained by reversing order of the bits in the 1178 * specified {@code long} value. 1179 * @since 1.5 1180 */ reverse(long i)1181 public static long reverse(long i) { 1182 // HD, Figure 7-1 1183 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L; 1184 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L; 1185 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL; 1186 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL; 1187 i = (i << 48) | ((i & 0xffff0000L) << 16) | 1188 ((i >>> 16) & 0xffff0000L) | (i >>> 48); 1189 return i; 1190 } 1191 1192 /** 1193 * Returns the signum function of the specified {@code long} value. (The 1194 * return value is -1 if the specified value is negative; 0 if the 1195 * specified value is zero; and 1 if the specified value is positive.) 1196 * 1197 * @return the signum function of the specified {@code long} value. 1198 * @since 1.5 1199 */ signum(long i)1200 public static int signum(long i) { 1201 // HD, Section 2-7 1202 return (int) ((i >> 63) | (-i >>> 63)); 1203 } 1204 1205 /** 1206 * Returns the value obtained by reversing the order of the bytes in the 1207 * two's complement representation of the specified {@code long} value. 1208 * 1209 * @return the value obtained by reversing the bytes in the specified 1210 * {@code long} value. 1211 * @since 1.5 1212 */ reverseBytes(long i)1213 public static long reverseBytes(long i) { 1214 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL; 1215 return (i << 48) | ((i & 0xffff0000L) << 16) | 1216 ((i >>> 16) & 0xffff0000L) | (i >>> 48); 1217 } 1218 1219 /** 1220 * Adds two {@code long} values together as per the + operator. 1221 * 1222 * @param a the first operand 1223 * @param b the second operand 1224 * @return the sum of {@code a} and {@code b} 1225 * @see java.util.function.BinaryOperator 1226 * @since 1.8 1227 */ sum(long a, long b)1228 public static long sum(long a, long b) { 1229 return a + b; 1230 } 1231 1232 /** 1233 * Returns the greater of two {@code long} values 1234 * as if by calling {@link Math#max(long, long) Math.max}. 1235 * 1236 * @param a the first operand 1237 * @param b the second operand 1238 * @return the greater of {@code a} and {@code b} 1239 * @see java.util.function.BinaryOperator 1240 * @since 1.8 1241 */ max(long a, long b)1242 public static long max(long a, long b) { 1243 return Math.max(a, b); 1244 } 1245 1246 /** 1247 * Returns the smaller of two {@code long} values 1248 * as if by calling {@link Math#min(long, long) Math.min}. 1249 * 1250 * @param a the first operand 1251 * @param b the second operand 1252 * @return the smaller of {@code a} and {@code b} 1253 * @see java.util.function.BinaryOperator 1254 * @since 1.8 1255 */ min(long a, long b)1256 public static long min(long a, long b) { 1257 return Math.min(a, b); 1258 } 1259 1260 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 1261 private static final long serialVersionUID = 4290774380558885855L; 1262 } 1263