J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1994-2006 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 | /** |
| 29 | * The {@code Long} class wraps a value of the primitive type {@code |
| 30 | * long} in an object. An object of type {@code Long} contains a |
| 31 | * single field whose type is {@code long}. |
| 32 | * |
| 33 | * <p> In addition, this class provides several methods for converting |
| 34 | * a {@code long} to a {@code String} and a {@code String} to a {@code |
| 35 | * long}, as well as other constants and methods useful when dealing |
| 36 | * with a {@code long}. |
| 37 | * |
| 38 | * <p>Implementation note: The implementations of the "bit twiddling" |
| 39 | * methods (such as {@link #highestOneBit(long) highestOneBit} and |
| 40 | * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are |
| 41 | * based on material from Henry S. Warren, Jr.'s <i>Hacker's |
| 42 | * Delight</i>, (Addison Wesley, 2002). |
| 43 | * |
| 44 | * @author Lee Boynton |
| 45 | * @author Arthur van Hoff |
| 46 | * @author Josh Bloch |
| 47 | * @author Joseph D. Darcy |
| 48 | * @since JDK1.0 |
| 49 | */ |
| 50 | public final class Long extends Number implements Comparable<Long> { |
| 51 | /** |
| 52 | * A constant holding the minimum value a {@code long} can |
| 53 | * have, -2<sup>63</sup>. |
| 54 | */ |
| 55 | public static final long MIN_VALUE = 0x8000000000000000L; |
| 56 | |
| 57 | /** |
| 58 | * A constant holding the maximum value a {@code long} can |
| 59 | * have, 2<sup>63</sup>-1. |
| 60 | */ |
| 61 | public static final long MAX_VALUE = 0x7fffffffffffffffL; |
| 62 | |
| 63 | /** |
| 64 | * The {@code Class} instance representing the primitive type |
| 65 | * {@code long}. |
| 66 | * |
| 67 | * @since JDK1.1 |
| 68 | */ |
| 69 | public static final Class<Long> TYPE = (Class<Long>) Class.getPrimitiveClass("long"); |
| 70 | |
| 71 | /** |
| 72 | * Returns a string representation of the first argument in the |
| 73 | * radix specified by the second argument. |
| 74 | * |
| 75 | * <p>If the radix is smaller than {@code Character.MIN_RADIX} |
| 76 | * or larger than {@code Character.MAX_RADIX}, then the radix |
| 77 | * {@code 10} is used instead. |
| 78 | * |
| 79 | * <p>If the first argument is negative, the first element of the |
| 80 | * result is the ASCII minus sign {@code '-'} |
| 81 | * (<code>'\u002d'</code>). If the first argument is not |
| 82 | * negative, no sign character appears in the result. |
| 83 | * |
| 84 | * <p>The remaining characters of the result represent the magnitude |
| 85 | * of the first argument. If the magnitude is zero, it is |
| 86 | * represented by a single zero character {@code '0'} |
| 87 | * (<code>'\u0030'</code>); otherwise, the first character of |
| 88 | * the representation of the magnitude will not be the zero |
| 89 | * character. The following ASCII characters are used as digits: |
| 90 | * |
| 91 | * <blockquote> |
| 92 | * {@code 0123456789abcdefghijklmnopqrstuvwxyz} |
| 93 | * </blockquote> |
| 94 | * |
| 95 | * These are <code>'\u0030'</code> through |
| 96 | * <code>'\u0039'</code> and <code>'\u0061'</code> through |
| 97 | * <code>'\u007a'</code>. If {@code radix} is |
| 98 | * <var>N</var>, then the first <var>N</var> of these characters |
| 99 | * are used as radix-<var>N</var> digits in the order shown. Thus, |
| 100 | * the digits for hexadecimal (radix 16) are |
| 101 | * {@code 0123456789abcdef}. If uppercase letters are |
| 102 | * desired, the {@link java.lang.String#toUpperCase()} method may |
| 103 | * be called on the result: |
| 104 | * |
| 105 | * <blockquote> |
| 106 | * {@code Long.toString(n, 16).toUpperCase()} |
| 107 | * </blockquote> |
| 108 | * |
| 109 | * @param i a {@code long} to be converted to a string. |
| 110 | * @param radix the radix to use in the string representation. |
| 111 | * @return a string representation of the argument in the specified radix. |
| 112 | * @see java.lang.Character#MAX_RADIX |
| 113 | * @see java.lang.Character#MIN_RADIX |
| 114 | */ |
| 115 | public static String toString(long i, int radix) { |
| 116 | if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) |
| 117 | radix = 10; |
| 118 | if (radix == 10) |
| 119 | return toString(i); |
| 120 | char[] buf = new char[65]; |
| 121 | int charPos = 64; |
| 122 | boolean negative = (i < 0); |
| 123 | |
| 124 | if (!negative) { |
| 125 | i = -i; |
| 126 | } |
| 127 | |
| 128 | while (i <= -radix) { |
| 129 | buf[charPos--] = Integer.digits[(int)(-(i % radix))]; |
| 130 | i = i / radix; |
| 131 | } |
| 132 | buf[charPos] = Integer.digits[(int)(-i)]; |
| 133 | |
| 134 | if (negative) { |
| 135 | buf[--charPos] = '-'; |
| 136 | } |
| 137 | |
| 138 | return new String(buf, charPos, (65 - charPos)); |
| 139 | } |
| 140 | |
| 141 | /** |
| 142 | * Returns a string representation of the {@code long} |
| 143 | * argument as an unsigned integer in base 16. |
| 144 | * |
| 145 | * <p>The unsigned {@code long} value is the argument plus |
| 146 | * 2<sup>64</sup> if the argument is negative; otherwise, it is |
| 147 | * equal to the argument. This value is converted to a string of |
| 148 | * ASCII digits in hexadecimal (base 16) with no extra |
| 149 | * leading {@code 0}s. If the unsigned magnitude is zero, it |
| 150 | * is represented by a single zero character {@code '0'} |
| 151 | * (<code>'\u0030'</code>); otherwise, the first character of |
| 152 | * the representation of the unsigned magnitude will not be the |
| 153 | * zero character. The following characters are used as |
| 154 | * hexadecimal digits: |
| 155 | * |
| 156 | * <blockquote> |
| 157 | * {@code 0123456789abcdef} |
| 158 | * </blockquote> |
| 159 | * |
| 160 | * These are the characters <code>'\u0030'</code> through |
| 161 | * <code>'\u0039'</code> and <code>'\u0061'</code> through |
| 162 | * <code>'\u0066'</code>. If uppercase letters are desired, |
| 163 | * the {@link java.lang.String#toUpperCase()} method may be called |
| 164 | * on the result: |
| 165 | * |
| 166 | * <blockquote> |
| 167 | * {@code Long.toHexString(n).toUpperCase()} |
| 168 | * </blockquote> |
| 169 | * |
| 170 | * @param i a {@code long} to be converted to a string. |
| 171 | * @return the string representation of the unsigned {@code long} |
| 172 | * value represented by the argument in hexadecimal |
| 173 | * (base 16). |
| 174 | * @since JDK 1.0.2 |
| 175 | */ |
| 176 | public static String toHexString(long i) { |
| 177 | return toUnsignedString(i, 4); |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * Returns a string representation of the {@code long} |
| 182 | * argument as an unsigned integer in base 8. |
| 183 | * |
| 184 | * <p>The unsigned {@code long} value is the argument plus |
| 185 | * 2<sup>64</sup> if the argument is negative; otherwise, it is |
| 186 | * equal to the argument. This value is converted to a string of |
| 187 | * ASCII digits in octal (base 8) with no extra leading |
| 188 | * {@code 0}s. |
| 189 | * |
| 190 | * <p>If the unsigned magnitude is zero, it is represented by a |
| 191 | * single zero character {@code '0'} |
| 192 | * (<code>'\u0030'</code>); otherwise, the first character of |
| 193 | * the representation of the unsigned magnitude will not be the |
| 194 | * zero character. The following characters are used as octal |
| 195 | * digits: |
| 196 | * |
| 197 | * <blockquote> |
| 198 | * {@code 01234567} |
| 199 | * </blockquote> |
| 200 | * |
| 201 | * These are the characters <code>'\u0030'</code> through |
| 202 | * <code>'\u0037'</code>. |
| 203 | * |
| 204 | * @param i a {@code long} to be converted to a string. |
| 205 | * @return the string representation of the unsigned {@code long} |
| 206 | * value represented by the argument in octal (base 8). |
| 207 | * @since JDK 1.0.2 |
| 208 | */ |
| 209 | public static String toOctalString(long i) { |
| 210 | return toUnsignedString(i, 3); |
| 211 | } |
| 212 | |
| 213 | /** |
| 214 | * Returns a string representation of the {@code long} |
| 215 | * argument as an unsigned integer in base 2. |
| 216 | * |
| 217 | * <p>The unsigned {@code long} value is the argument plus |
| 218 | * 2<sup>64</sup> if the argument is negative; otherwise, it is |
| 219 | * equal to the argument. This value is converted to a string of |
| 220 | * ASCII digits in binary (base 2) with no extra leading |
| 221 | * {@code 0}s. If the unsigned magnitude is zero, it is |
| 222 | * represented by a single zero character {@code '0'} |
| 223 | * (<code>'\u0030'</code>); otherwise, the first character of |
| 224 | * the representation of the unsigned magnitude will not be the |
| 225 | * zero character. The characters {@code '0'} |
| 226 | * (<code>'\u0030'</code>) and {@code '1'} |
| 227 | * (<code>'\u0031'</code>) are used as binary digits. |
| 228 | * |
| 229 | * @param i a {@code long} to be converted to a string. |
| 230 | * @return the string representation of the unsigned {@code long} |
| 231 | * value represented by the argument in binary (base 2). |
| 232 | * @since JDK 1.0.2 |
| 233 | */ |
| 234 | public static String toBinaryString(long i) { |
| 235 | return toUnsignedString(i, 1); |
| 236 | } |
| 237 | |
| 238 | /** |
| 239 | * Convert the integer to an unsigned number. |
| 240 | */ |
| 241 | private static String toUnsignedString(long i, int shift) { |
| 242 | char[] buf = new char[64]; |
| 243 | int charPos = 64; |
| 244 | int radix = 1 << shift; |
| 245 | long mask = radix - 1; |
| 246 | do { |
| 247 | buf[--charPos] = Integer.digits[(int)(i & mask)]; |
| 248 | i >>>= shift; |
| 249 | } while (i != 0); |
| 250 | return new String(buf, charPos, (64 - charPos)); |
| 251 | } |
| 252 | |
| 253 | /** |
| 254 | * Returns a {@code String} object representing the specified |
| 255 | * {@code long}. The argument is converted to signed decimal |
| 256 | * representation and returned as a string, exactly as if the |
| 257 | * argument and the radix 10 were given as arguments to the {@link |
| 258 | * #toString(long, int)} method. |
| 259 | * |
| 260 | * @param i a {@code long} to be converted. |
| 261 | * @return a string representation of the argument in base 10. |
| 262 | */ |
| 263 | public static String toString(long i) { |
| 264 | if (i == Long.MIN_VALUE) |
| 265 | return "-9223372036854775808"; |
| 266 | int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i); |
| 267 | char[] buf = new char[size]; |
| 268 | getChars(i, size, buf); |
| 269 | return new String(0, size, buf); |
| 270 | } |
| 271 | |
| 272 | /** |
| 273 | * Places characters representing the integer i into the |
| 274 | * character array buf. The characters are placed into |
| 275 | * the buffer backwards starting with the least significant |
| 276 | * digit at the specified index (exclusive), and working |
| 277 | * backwards from there. |
| 278 | * |
| 279 | * Will fail if i == Long.MIN_VALUE |
| 280 | */ |
| 281 | static void getChars(long i, int index, char[] buf) { |
| 282 | long q; |
| 283 | int r; |
| 284 | int charPos = index; |
| 285 | char sign = 0; |
| 286 | |
| 287 | if (i < 0) { |
| 288 | sign = '-'; |
| 289 | i = -i; |
| 290 | } |
| 291 | |
| 292 | // Get 2 digits/iteration using longs until quotient fits into an int |
| 293 | while (i > Integer.MAX_VALUE) { |
| 294 | q = i / 100; |
| 295 | // really: r = i - (q * 100); |
| 296 | r = (int)(i - ((q << 6) + (q << 5) + (q << 2))); |
| 297 | i = q; |
| 298 | buf[--charPos] = Integer.DigitOnes[r]; |
| 299 | buf[--charPos] = Integer.DigitTens[r]; |
| 300 | } |
| 301 | |
| 302 | // Get 2 digits/iteration using ints |
| 303 | int q2; |
| 304 | int i2 = (int)i; |
| 305 | while (i2 >= 65536) { |
| 306 | q2 = i2 / 100; |
| 307 | // really: r = i2 - (q * 100); |
| 308 | r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2)); |
| 309 | i2 = q2; |
| 310 | buf[--charPos] = Integer.DigitOnes[r]; |
| 311 | buf[--charPos] = Integer.DigitTens[r]; |
| 312 | } |
| 313 | |
| 314 | // Fall thru to fast mode for smaller numbers |
| 315 | // assert(i2 <= 65536, i2); |
| 316 | for (;;) { |
| 317 | q2 = (i2 * 52429) >>> (16+3); |
| 318 | r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ... |
| 319 | buf[--charPos] = Integer.digits[r]; |
| 320 | i2 = q2; |
| 321 | if (i2 == 0) break; |
| 322 | } |
| 323 | if (sign != 0) { |
| 324 | buf[--charPos] = sign; |
| 325 | } |
| 326 | } |
| 327 | |
| 328 | // Requires positive x |
| 329 | static int stringSize(long x) { |
| 330 | long p = 10; |
| 331 | for (int i=1; i<19; i++) { |
| 332 | if (x < p) |
| 333 | return i; |
| 334 | p = 10*p; |
| 335 | } |
| 336 | return 19; |
| 337 | } |
| 338 | |
| 339 | /** |
| 340 | * Parses the string argument as a signed {@code long} in the |
| 341 | * radix specified by the second argument. The characters in the |
| 342 | * string must all be digits of the specified radix (as determined |
| 343 | * by whether {@link java.lang.Character#digit(char, int)} returns |
| 344 | * a nonnegative value), except that the first character may be an |
| 345 | * ASCII minus sign {@code '-'} (<code>'\u002D'</code>) to |
| 346 | * indicate a negative value or an ASCII plus sign {@code '+'} |
| 347 | * (<code>'\u002B'</code>) to indicate a positive value. The |
| 348 | * resulting {@code long} value is returned. |
| 349 | * |
| 350 | * <p>Note that neither the character {@code L} |
| 351 | * (<code>'\u004C'</code>) nor {@code l} |
| 352 | * (<code>'\u006C'</code>) is permitted to appear at the end |
| 353 | * of the string as a type indicator, as would be permitted in |
| 354 | * Java programming language source code - except that either |
| 355 | * {@code L} or {@code l} may appear as a digit for a |
| 356 | * radix greater than 22. |
| 357 | * |
| 358 | * <p>An exception of type {@code NumberFormatException} is |
| 359 | * thrown if any of the following situations occurs: |
| 360 | * <ul> |
| 361 | * |
| 362 | * <li>The first argument is {@code null} or is a string of |
| 363 | * length zero. |
| 364 | * |
| 365 | * <li>The {@code radix} is either smaller than {@link |
| 366 | * java.lang.Character#MIN_RADIX} or larger than {@link |
| 367 | * java.lang.Character#MAX_RADIX}. |
| 368 | * |
| 369 | * <li>Any character of the string is not a digit of the specified |
| 370 | * radix, except that the first character may be a minus sign |
| 371 | * {@code '-'} (<code>'\u002d'</code>) or plus sign {@code |
| 372 | * '+'} (<code>'\u002B'</code>) provided that the string is |
| 373 | * longer than length 1. |
| 374 | * |
| 375 | * <li>The value represented by the string is not a value of type |
| 376 | * {@code long}. |
| 377 | * </ul> |
| 378 | * |
| 379 | * <p>Examples: |
| 380 | * <blockquote><pre> |
| 381 | * parseLong("0", 10) returns 0L |
| 382 | * parseLong("473", 10) returns 473L |
| 383 | * parseLong("+42", 10) returns 42L |
| 384 | * parseLong("-0", 10) returns 0L |
| 385 | * parseLong("-FF", 16) returns -255L |
| 386 | * parseLong("1100110", 2) returns 102L |
| 387 | * parseLong("99", 8) throws a NumberFormatException |
| 388 | * parseLong("Hazelnut", 10) throws a NumberFormatException |
| 389 | * parseLong("Hazelnut", 36) returns 1356099454469L |
| 390 | * </pre></blockquote> |
| 391 | * |
| 392 | * @param s the {@code String} containing the |
| 393 | * {@code long} representation to be parsed. |
| 394 | * @param radix the radix to be used while parsing {@code s}. |
| 395 | * @return the {@code long} represented by the string argument in |
| 396 | * the specified radix. |
| 397 | * @throws NumberFormatException if the string does not contain a |
| 398 | * parsable {@code long}. |
| 399 | */ |
| 400 | public static long parseLong(String s, int radix) |
| 401 | throws NumberFormatException |
| 402 | { |
| 403 | if (s == null) { |
| 404 | throw new NumberFormatException("null"); |
| 405 | } |
| 406 | |
| 407 | if (radix < Character.MIN_RADIX) { |
| 408 | throw new NumberFormatException("radix " + radix + |
| 409 | " less than Character.MIN_RADIX"); |
| 410 | } |
| 411 | if (radix > Character.MAX_RADIX) { |
| 412 | throw new NumberFormatException("radix " + radix + |
| 413 | " greater than Character.MAX_RADIX"); |
| 414 | } |
| 415 | |
| 416 | long result = 0; |
| 417 | boolean negative = false; |
| 418 | int i = 0, len = s.length(); |
| 419 | long limit = -Long.MAX_VALUE; |
| 420 | long multmin; |
| 421 | int digit; |
| 422 | |
| 423 | if (len > 0) { |
| 424 | char firstChar = s.charAt(0); |
| 425 | if (firstChar < '0') { // Possible leading "+" or "-" |
| 426 | if (firstChar == '-') { |
| 427 | negative = true; |
| 428 | limit = Long.MIN_VALUE; |
| 429 | } else if (firstChar != '+') |
| 430 | throw NumberFormatException.forInputString(s); |
| 431 | |
| 432 | if (len == 1) // Cannot have lone "+" or "-" |
| 433 | throw NumberFormatException.forInputString(s); |
| 434 | i++; |
| 435 | } |
| 436 | multmin = limit / radix; |
| 437 | while (i < len) { |
| 438 | // Accumulating negatively avoids surprises near MAX_VALUE |
| 439 | digit = Character.digit(s.charAt(i++),radix); |
| 440 | if (digit < 0) { |
| 441 | throw NumberFormatException.forInputString(s); |
| 442 | } |
| 443 | if (result < multmin) { |
| 444 | throw NumberFormatException.forInputString(s); |
| 445 | } |
| 446 | result *= radix; |
| 447 | if (result < limit + digit) { |
| 448 | throw NumberFormatException.forInputString(s); |
| 449 | } |
| 450 | result -= digit; |
| 451 | } |
| 452 | } else { |
| 453 | throw NumberFormatException.forInputString(s); |
| 454 | } |
| 455 | return negative ? result : -result; |
| 456 | } |
| 457 | |
| 458 | /** |
| 459 | * Parses the string argument as a signed decimal {@code long}. |
| 460 | * The characters in the string must all be decimal digits, except |
| 461 | * that the first character may be an ASCII minus sign {@code '-'} |
| 462 | * (<code>\u002D'</code>) to indicate a negative value or an |
| 463 | * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to |
| 464 | * indicate a positive value. The resulting {@code long} value is |
| 465 | * returned, exactly as if the argument and the radix {@code 10} |
| 466 | * were given as arguments to the {@link |
| 467 | * #parseLong(java.lang.String, int)} method. |
| 468 | * |
| 469 | * <p>Note that neither the character {@code L} |
| 470 | * (<code>'\u004C'</code>) nor {@code l} |
| 471 | * (<code>'\u006C'</code>) is permitted to appear at the end |
| 472 | * of the string as a type indicator, as would be permitted in |
| 473 | * Java programming language source code. |
| 474 | * |
| 475 | * @param s a {@code String} containing the {@code long} |
| 476 | * representation to be parsed |
| 477 | * @return the {@code long} represented by the argument in |
| 478 | * decimal. |
| 479 | * @throws NumberFormatException if the string does not contain a |
| 480 | * parsable {@code long}. |
| 481 | */ |
| 482 | public static long parseLong(String s) throws NumberFormatException { |
| 483 | return parseLong(s, 10); |
| 484 | } |
| 485 | |
| 486 | /** |
| 487 | * Returns a {@code Long} object holding the value |
| 488 | * extracted from the specified {@code String} when parsed |
| 489 | * with the radix given by the second argument. The first |
| 490 | * argument is interpreted as representing a signed |
| 491 | * {@code long} in the radix specified by the second |
| 492 | * argument, exactly as if the arguments were given to the {@link |
| 493 | * #parseLong(java.lang.String, int)} method. The result is a |
| 494 | * {@code Long} object that represents the {@code long} |
| 495 | * value specified by the string. |
| 496 | * |
| 497 | * <p>In other words, this method returns a {@code Long} object equal |
| 498 | * to the value of: |
| 499 | * |
| 500 | * <blockquote> |
| 501 | * {@code new Long(Long.parseLong(s, radix))} |
| 502 | * </blockquote> |
| 503 | * |
| 504 | * @param s the string to be parsed |
| 505 | * @param radix the radix to be used in interpreting {@code s} |
| 506 | * @return a {@code Long} object holding the value |
| 507 | * represented by the string argument in the specified |
| 508 | * radix. |
| 509 | * @throws NumberFormatException If the {@code String} does not |
| 510 | * contain a parsable {@code long}. |
| 511 | */ |
| 512 | public static Long valueOf(String s, int radix) throws NumberFormatException { |
| 513 | return new Long(parseLong(s, radix)); |
| 514 | } |
| 515 | |
| 516 | /** |
| 517 | * Returns a {@code Long} object holding the value |
| 518 | * of the specified {@code String}. The argument is |
| 519 | * interpreted as representing a signed decimal {@code long}, |
| 520 | * exactly as if the argument were given to the {@link |
| 521 | * #parseLong(java.lang.String)} method. The result is a |
| 522 | * {@code Long} object that represents the integer value |
| 523 | * specified by the string. |
| 524 | * |
| 525 | * <p>In other words, this method returns a {@code Long} object |
| 526 | * equal to the value of: |
| 527 | * |
| 528 | * <blockquote> |
| 529 | * {@code new Long(Long.parseLong(s))} |
| 530 | * </blockquote> |
| 531 | * |
| 532 | * @param s the string to be parsed. |
| 533 | * @return a {@code Long} object holding the value |
| 534 | * represented by the string argument. |
| 535 | * @throws NumberFormatException If the string cannot be parsed |
| 536 | * as a {@code long}. |
| 537 | */ |
| 538 | public static Long valueOf(String s) throws NumberFormatException |
| 539 | { |
| 540 | return new Long(parseLong(s, 10)); |
| 541 | } |
| 542 | |
| 543 | private static class LongCache { |
| 544 | private LongCache(){} |
| 545 | |
| 546 | static final Long cache[] = new Long[-(-128) + 127 + 1]; |
| 547 | |
| 548 | static { |
| 549 | for(int i = 0; i < cache.length; i++) |
| 550 | cache[i] = new Long(i - 128); |
| 551 | } |
| 552 | } |
| 553 | |
| 554 | /** |
| 555 | * Returns a {@code Long} instance representing the specified |
| 556 | * {@code long} value. |
| 557 | * If a new {@code Long} instance is not required, this method |
| 558 | * should generally be used in preference to the constructor |
| 559 | * {@link #Long(long)}, as this method is likely to yield |
| 560 | * significantly better space and time performance by caching |
| 561 | * frequently requested values. |
| 562 | * |
| 563 | * @param l a long value. |
| 564 | * @return a {@code Long} instance representing {@code l}. |
| 565 | * @since 1.5 |
| 566 | */ |
| 567 | public static Long valueOf(long l) { |
| 568 | final int offset = 128; |
| 569 | if (l >= -128 && l <= 127) { // will cache |
| 570 | return LongCache.cache[(int)l + offset]; |
| 571 | } |
| 572 | return new Long(l); |
| 573 | } |
| 574 | |
| 575 | /** |
| 576 | * Decodes a {@code String} into a {@code Long}. |
| 577 | * Accepts decimal, hexadecimal, and octal numbers given by the |
| 578 | * following grammar: |
| 579 | * |
| 580 | * <blockquote> |
| 581 | * <dl> |
| 582 | * <dt><i>DecodableString:</i> |
| 583 | * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> |
| 584 | * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> |
| 585 | * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> |
| 586 | * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> |
| 587 | * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> |
| 588 | * <p> |
| 589 | * <dt><i>Sign:</i> |
| 590 | * <dd>{@code -} |
| 591 | * <dd>{@code +} |
| 592 | * </dl> |
| 593 | * </blockquote> |
| 594 | * |
| 595 | * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> |
| 596 | * are defined in <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">§3.10.1</a> |
| 597 | * of the <a href="http://java.sun.com/docs/books/jls/html/">Java |
| 598 | * Language Specification</a>. |
| 599 | * |
| 600 | * <p>The sequence of characters following an optional |
| 601 | * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", |
| 602 | * "{@code #}", or leading zero) is parsed as by the {@code |
| 603 | * Long.parseLong} method with the indicated radix (10, 16, or 8). |
| 604 | * This sequence of characters must represent a positive value or |
| 605 | * a {@link NumberFormatException} will be thrown. The result is |
| 606 | * negated if first character of the specified {@code String} is |
| 607 | * the minus sign. No whitespace characters are permitted in the |
| 608 | * {@code String}. |
| 609 | * |
| 610 | * @param nm the {@code String} to decode. |
| 611 | * @return a {@code Long} object holding the {@code long} |
| 612 | * value represented by {@code nm} |
| 613 | * @throws NumberFormatException if the {@code String} does not |
| 614 | * contain a parsable {@code long}. |
| 615 | * @see java.lang.Long#parseLong(String, int) |
| 616 | * @since 1.2 |
| 617 | */ |
| 618 | public static Long decode(String nm) throws NumberFormatException { |
| 619 | int radix = 10; |
| 620 | int index = 0; |
| 621 | boolean negative = false; |
| 622 | Long result; |
| 623 | |
| 624 | if (nm.length() == 0) |
| 625 | throw new NumberFormatException("Zero length string"); |
| 626 | char firstChar = nm.charAt(0); |
| 627 | // Handle sign, if present |
| 628 | if (firstChar == '-') { |
| 629 | negative = true; |
| 630 | index++; |
| 631 | } else if (firstChar == '+') |
| 632 | index++; |
| 633 | |
| 634 | // Handle radix specifier, if present |
| 635 | if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) { |
| 636 | index += 2; |
| 637 | radix = 16; |
| 638 | } |
| 639 | else if (nm.startsWith("#", index)) { |
| 640 | index ++; |
| 641 | radix = 16; |
| 642 | } |
| 643 | else if (nm.startsWith("0", index) && nm.length() > 1 + index) { |
| 644 | index ++; |
| 645 | radix = 8; |
| 646 | } |
| 647 | |
| 648 | if (nm.startsWith("-", index) || nm.startsWith("+", index)) |
| 649 | throw new NumberFormatException("Sign character in wrong position"); |
| 650 | |
| 651 | try { |
| 652 | result = Long.valueOf(nm.substring(index), radix); |
| 653 | result = negative ? new Long((long)-result.longValue()) : result; |
| 654 | } catch (NumberFormatException e) { |
| 655 | // If number is Long.MIN_VALUE, we'll end up here. The next line |
| 656 | // handles this case, and causes any genuine format error to be |
| 657 | // rethrown. |
| 658 | String constant = negative ? ("-" + nm.substring(index)) |
| 659 | : nm.substring(index); |
| 660 | result = Long.valueOf(constant, radix); |
| 661 | } |
| 662 | return result; |
| 663 | } |
| 664 | |
| 665 | /** |
| 666 | * The value of the {@code Long}. |
| 667 | * |
| 668 | * @serial |
| 669 | */ |
| 670 | private final long value; |
| 671 | |
| 672 | /** |
| 673 | * Constructs a newly allocated {@code Long} object that |
| 674 | * represents the specified {@code long} argument. |
| 675 | * |
| 676 | * @param value the value to be represented by the |
| 677 | * {@code Long} object. |
| 678 | */ |
| 679 | public Long(long value) { |
| 680 | this.value = value; |
| 681 | } |
| 682 | |
| 683 | /** |
| 684 | * Constructs a newly allocated {@code Long} object that |
| 685 | * represents the {@code long} value indicated by the |
| 686 | * {@code String} parameter. The string is converted to a |
| 687 | * {@code long} value in exactly the manner used by the |
| 688 | * {@code parseLong} method for radix 10. |
| 689 | * |
| 690 | * @param s the {@code String} to be converted to a |
| 691 | * {@code Long}. |
| 692 | * @throws NumberFormatException if the {@code String} does not |
| 693 | * contain a parsable {@code long}. |
| 694 | * @see java.lang.Long#parseLong(java.lang.String, int) |
| 695 | */ |
| 696 | public Long(String s) throws NumberFormatException { |
| 697 | this.value = parseLong(s, 10); |
| 698 | } |
| 699 | |
| 700 | /** |
| 701 | * Returns the value of this {@code Long} as a |
| 702 | * {@code byte}. |
| 703 | */ |
| 704 | public byte byteValue() { |
| 705 | return (byte)value; |
| 706 | } |
| 707 | |
| 708 | /** |
| 709 | * Returns the value of this {@code Long} as a |
| 710 | * {@code short}. |
| 711 | */ |
| 712 | public short shortValue() { |
| 713 | return (short)value; |
| 714 | } |
| 715 | |
| 716 | /** |
| 717 | * Returns the value of this {@code Long} as an |
| 718 | * {@code int}. |
| 719 | */ |
| 720 | public int intValue() { |
| 721 | return (int)value; |
| 722 | } |
| 723 | |
| 724 | /** |
| 725 | * Returns the value of this {@code Long} as a |
| 726 | * {@code long} value. |
| 727 | */ |
| 728 | public long longValue() { |
| 729 | return (long)value; |
| 730 | } |
| 731 | |
| 732 | /** |
| 733 | * Returns the value of this {@code Long} as a |
| 734 | * {@code float}. |
| 735 | */ |
| 736 | public float floatValue() { |
| 737 | return (float)value; |
| 738 | } |
| 739 | |
| 740 | /** |
| 741 | * Returns the value of this {@code Long} as a |
| 742 | * {@code double}. |
| 743 | */ |
| 744 | public double doubleValue() { |
| 745 | return (double)value; |
| 746 | } |
| 747 | |
| 748 | /** |
| 749 | * Returns a {@code String} object representing this |
| 750 | * {@code Long}'s value. The value is converted to signed |
| 751 | * decimal representation and returned as a string, exactly as if |
| 752 | * the {@code long} value were given as an argument to the |
| 753 | * {@link java.lang.Long#toString(long)} method. |
| 754 | * |
| 755 | * @return a string representation of the value of this object in |
| 756 | * base 10. |
| 757 | */ |
| 758 | public String toString() { |
| 759 | return String.valueOf(value); |
| 760 | } |
| 761 | |
| 762 | /** |
| 763 | * Returns a hash code for this {@code Long}. The result is |
| 764 | * the exclusive OR of the two halves of the primitive |
| 765 | * {@code long} value held by this {@code Long} |
| 766 | * object. That is, the hashcode is the value of the expression: |
| 767 | * |
| 768 | * <blockquote> |
| 769 | * {@code (int)(this.longValue()^(this.longValue()>>>32))} |
| 770 | * </blockquote> |
| 771 | * |
| 772 | * @return a hash code value for this object. |
| 773 | */ |
| 774 | public int hashCode() { |
| 775 | return (int)(value ^ (value >>> 32)); |
| 776 | } |
| 777 | |
| 778 | /** |
| 779 | * Compares this object to the specified object. The result is |
| 780 | * {@code true} if and only if the argument is not |
| 781 | * {@code null} and is a {@code Long} object that |
| 782 | * contains the same {@code long} value as this object. |
| 783 | * |
| 784 | * @param obj the object to compare with. |
| 785 | * @return {@code true} if the objects are the same; |
| 786 | * {@code false} otherwise. |
| 787 | */ |
| 788 | public boolean equals(Object obj) { |
| 789 | if (obj instanceof Long) { |
| 790 | return value == ((Long)obj).longValue(); |
| 791 | } |
| 792 | return false; |
| 793 | } |
| 794 | |
| 795 | /** |
| 796 | * Determines the {@code long} value of the system property |
| 797 | * with the specified name. |
| 798 | * |
| 799 | * <p>The first argument is treated as the name of a system property. |
| 800 | * System properties are accessible through the {@link |
| 801 | * java.lang.System#getProperty(java.lang.String)} method. The |
| 802 | * string value of this property is then interpreted as a |
| 803 | * {@code long} value and a {@code Long} object |
| 804 | * representing this value is returned. Details of possible |
| 805 | * numeric formats can be found with the definition of |
| 806 | * {@code getProperty}. |
| 807 | * |
| 808 | * <p>If there is no property with the specified name, if the |
| 809 | * specified name is empty or {@code null}, or if the |
| 810 | * property does not have the correct numeric format, then |
| 811 | * {@code null} is returned. |
| 812 | * |
| 813 | * <p>In other words, this method returns a {@code Long} object equal to |
| 814 | * the value of: |
| 815 | * |
| 816 | * <blockquote> |
| 817 | * {@code getLong(nm, null)} |
| 818 | * </blockquote> |
| 819 | * |
| 820 | * @param nm property name. |
| 821 | * @return the {@code Long} value of the property. |
| 822 | * @see java.lang.System#getProperty(java.lang.String) |
| 823 | * @see java.lang.System#getProperty(java.lang.String, java.lang.String) |
| 824 | */ |
| 825 | public static Long getLong(String nm) { |
| 826 | return getLong(nm, null); |
| 827 | } |
| 828 | |
| 829 | /** |
| 830 | * Determines the {@code long} value of the system property |
| 831 | * with the specified name. |
| 832 | * |
| 833 | * <p>The first argument is treated as the name of a system property. |
| 834 | * System properties are accessible through the {@link |
| 835 | * java.lang.System#getProperty(java.lang.String)} method. The |
| 836 | * string value of this property is then interpreted as a |
| 837 | * {@code long} value and a {@code Long} object |
| 838 | * representing this value is returned. Details of possible |
| 839 | * numeric formats can be found with the definition of |
| 840 | * {@code getProperty}. |
| 841 | * |
| 842 | * <p>The second argument is the default value. A {@code Long} object |
| 843 | * that represents the value of the second argument is returned if there |
| 844 | * is no property of the specified name, if the property does not have |
| 845 | * the correct numeric format, or if the specified name is empty or null. |
| 846 | * |
| 847 | * <p>In other words, this method returns a {@code Long} object equal |
| 848 | * to the value of: |
| 849 | * |
| 850 | * <blockquote> |
| 851 | * {@code getLong(nm, new Long(val))} |
| 852 | * </blockquote> |
| 853 | * |
| 854 | * but in practice it may be implemented in a manner such as: |
| 855 | * |
| 856 | * <blockquote><pre> |
| 857 | * Long result = getLong(nm, null); |
| 858 | * return (result == null) ? new Long(val) : result; |
| 859 | * </pre></blockquote> |
| 860 | * |
| 861 | * to avoid the unnecessary allocation of a {@code Long} object when |
| 862 | * the default value is not needed. |
| 863 | * |
| 864 | * @param nm property name. |
| 865 | * @param val default value. |
| 866 | * @return the {@code Long} value of the property. |
| 867 | * @see java.lang.System#getProperty(java.lang.String) |
| 868 | * @see java.lang.System#getProperty(java.lang.String, java.lang.String) |
| 869 | */ |
| 870 | public static Long getLong(String nm, long val) { |
| 871 | Long result = Long.getLong(nm, null); |
| 872 | return (result == null) ? new Long(val) : result; |
| 873 | } |
| 874 | |
| 875 | /** |
| 876 | * Returns the {@code long} value of the system property with |
| 877 | * the specified name. The first argument is treated as the name |
| 878 | * of a system property. System properties are accessible through |
| 879 | * the {@link java.lang.System#getProperty(java.lang.String)} |
| 880 | * method. The string value of this property is then interpreted |
| 881 | * as a {@code long} value, as per the |
| 882 | * {@code Long.decode} method, and a {@code Long} object |
| 883 | * representing this value is returned. |
| 884 | * |
| 885 | * <ul> |
| 886 | * <li>If the property value begins with the two ASCII characters |
| 887 | * {@code 0x} or the ASCII character {@code #}, not followed by |
| 888 | * a minus sign, then the rest of it is parsed as a hexadecimal integer |
| 889 | * exactly as for the method {@link #valueOf(java.lang.String, int)} |
| 890 | * with radix 16. |
| 891 | * <li>If the property value begins with the ASCII character |
| 892 | * {@code 0} followed by another character, it is parsed as |
| 893 | * an octal integer exactly as by the method {@link |
| 894 | * #valueOf(java.lang.String, int)} with radix 8. |
| 895 | * <li>Otherwise the property value is parsed as a decimal |
| 896 | * integer exactly as by the method |
| 897 | * {@link #valueOf(java.lang.String, int)} with radix 10. |
| 898 | * </ul> |
| 899 | * |
| 900 | * <p>Note that, in every case, neither {@code L} |
| 901 | * (<code>'\u004C'</code>) nor {@code l} |
| 902 | * (<code>'\u006C'</code>) is permitted to appear at the end |
| 903 | * of the property value as a type indicator, as would be |
| 904 | * permitted in Java programming language source code. |
| 905 | * |
| 906 | * <p>The second argument is the default value. The default value is |
| 907 | * returned if there is no property of the specified name, if the |
| 908 | * property does not have the correct numeric format, or if the |
| 909 | * specified name is empty or {@code null}. |
| 910 | * |
| 911 | * @param nm property name. |
| 912 | * @param val default value. |
| 913 | * @return the {@code Long} value of the property. |
| 914 | * @see java.lang.System#getProperty(java.lang.String) |
| 915 | * @see java.lang.System#getProperty(java.lang.String, java.lang.String) |
| 916 | * @see java.lang.Long#decode |
| 917 | */ |
| 918 | public static Long getLong(String nm, Long val) { |
| 919 | String v = null; |
| 920 | try { |
| 921 | v = System.getProperty(nm); |
| 922 | } catch (IllegalArgumentException e) { |
| 923 | } catch (NullPointerException e) { |
| 924 | } |
| 925 | if (v != null) { |
| 926 | try { |
| 927 | return Long.decode(v); |
| 928 | } catch (NumberFormatException e) { |
| 929 | } |
| 930 | } |
| 931 | return val; |
| 932 | } |
| 933 | |
| 934 | /** |
| 935 | * Compares two {@code Long} objects numerically. |
| 936 | * |
| 937 | * @param anotherLong the {@code Long} to be compared. |
| 938 | * @return the value {@code 0} if this {@code Long} is |
| 939 | * equal to the argument {@code Long}; a value less than |
| 940 | * {@code 0} if this {@code Long} is numerically less |
| 941 | * than the argument {@code Long}; and a value greater |
| 942 | * than {@code 0} if this {@code Long} is numerically |
| 943 | * greater than the argument {@code Long} (signed |
| 944 | * comparison). |
| 945 | * @since 1.2 |
| 946 | */ |
| 947 | public int compareTo(Long anotherLong) { |
| 948 | long thisVal = this.value; |
| 949 | long anotherVal = anotherLong.value; |
| 950 | return (thisVal<anotherVal ? -1 : (thisVal==anotherVal ? 0 : 1)); |
| 951 | } |
| 952 | |
| 953 | |
| 954 | // Bit Twiddling |
| 955 | |
| 956 | /** |
| 957 | * The number of bits used to represent a {@code long} value in two's |
| 958 | * complement binary form. |
| 959 | * |
| 960 | * @since 1.5 |
| 961 | */ |
| 962 | public static final int SIZE = 64; |
| 963 | |
| 964 | /** |
| 965 | * Returns a {@code long} value with at most a single one-bit, in the |
| 966 | * position of the highest-order ("leftmost") one-bit in the specified |
| 967 | * {@code long} value. Returns zero if the specified value has no |
| 968 | * one-bits in its two's complement binary representation, that is, if it |
| 969 | * is equal to zero. |
| 970 | * |
| 971 | * @return a {@code long} value with a single one-bit, in the position |
| 972 | * of the highest-order one-bit in the specified value, or zero if |
| 973 | * the specified value is itself equal to zero. |
| 974 | * @since 1.5 |
| 975 | */ |
| 976 | public static long highestOneBit(long i) { |
| 977 | // HD, Figure 3-1 |
| 978 | i |= (i >> 1); |
| 979 | i |= (i >> 2); |
| 980 | i |= (i >> 4); |
| 981 | i |= (i >> 8); |
| 982 | i |= (i >> 16); |
| 983 | i |= (i >> 32); |
| 984 | return i - (i >>> 1); |
| 985 | } |
| 986 | |
| 987 | /** |
| 988 | * Returns a {@code long} value with at most a single one-bit, in the |
| 989 | * position of the lowest-order ("rightmost") one-bit in the specified |
| 990 | * {@code long} value. Returns zero if the specified value has no |
| 991 | * one-bits in its two's complement binary representation, that is, if it |
| 992 | * is equal to zero. |
| 993 | * |
| 994 | * @return a {@code long} value with a single one-bit, in the position |
| 995 | * of the lowest-order one-bit in the specified value, or zero if |
| 996 | * the specified value is itself equal to zero. |
| 997 | * @since 1.5 |
| 998 | */ |
| 999 | public static long lowestOneBit(long i) { |
| 1000 | // HD, Section 2-1 |
| 1001 | return i & -i; |
| 1002 | } |
| 1003 | |
| 1004 | /** |
| 1005 | * Returns the number of zero bits preceding the highest-order |
| 1006 | * ("leftmost") one-bit in the two's complement binary representation |
| 1007 | * of the specified {@code long} value. Returns 64 if the |
| 1008 | * specified value has no one-bits in its two's complement representation, |
| 1009 | * in other words if it is equal to zero. |
| 1010 | * |
| 1011 | * <p>Note that this method is closely related to the logarithm base 2. |
| 1012 | * For all positive {@code long} values x: |
| 1013 | * <ul> |
| 1014 | * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)} |
| 1015 | * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)} |
| 1016 | * </ul> |
| 1017 | * |
| 1018 | * @return the number of zero bits preceding the highest-order |
| 1019 | * ("leftmost") one-bit in the two's complement binary representation |
| 1020 | * of the specified {@code long} value, or 64 if the value |
| 1021 | * is equal to zero. |
| 1022 | * @since 1.5 |
| 1023 | */ |
| 1024 | public static int numberOfLeadingZeros(long i) { |
| 1025 | // HD, Figure 5-6 |
| 1026 | if (i == 0) |
| 1027 | return 64; |
| 1028 | int n = 1; |
| 1029 | int x = (int)(i >>> 32); |
| 1030 | if (x == 0) { n += 32; x = (int)i; } |
| 1031 | if (x >>> 16 == 0) { n += 16; x <<= 16; } |
| 1032 | if (x >>> 24 == 0) { n += 8; x <<= 8; } |
| 1033 | if (x >>> 28 == 0) { n += 4; x <<= 4; } |
| 1034 | if (x >>> 30 == 0) { n += 2; x <<= 2; } |
| 1035 | n -= x >>> 31; |
| 1036 | return n; |
| 1037 | } |
| 1038 | |
| 1039 | /** |
| 1040 | * Returns the number of zero bits following the lowest-order ("rightmost") |
| 1041 | * one-bit in the two's complement binary representation of the specified |
| 1042 | * {@code long} value. Returns 64 if the specified value has no |
| 1043 | * one-bits in its two's complement representation, in other words if it is |
| 1044 | * equal to zero. |
| 1045 | * |
| 1046 | * @return the number of zero bits following the lowest-order ("rightmost") |
| 1047 | * one-bit in the two's complement binary representation of the |
| 1048 | * specified {@code long} value, or 64 if the value is equal |
| 1049 | * to zero. |
| 1050 | * @since 1.5 |
| 1051 | */ |
| 1052 | public static int numberOfTrailingZeros(long i) { |
| 1053 | // HD, Figure 5-14 |
| 1054 | int x, y; |
| 1055 | if (i == 0) return 64; |
| 1056 | int n = 63; |
| 1057 | y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32); |
| 1058 | y = x <<16; if (y != 0) { n = n -16; x = y; } |
| 1059 | y = x << 8; if (y != 0) { n = n - 8; x = y; } |
| 1060 | y = x << 4; if (y != 0) { n = n - 4; x = y; } |
| 1061 | y = x << 2; if (y != 0) { n = n - 2; x = y; } |
| 1062 | return n - ((x << 1) >>> 31); |
| 1063 | } |
| 1064 | |
| 1065 | /** |
| 1066 | * Returns the number of one-bits in the two's complement binary |
| 1067 | * representation of the specified {@code long} value. This function is |
| 1068 | * sometimes referred to as the <i>population count</i>. |
| 1069 | * |
| 1070 | * @return the number of one-bits in the two's complement binary |
| 1071 | * representation of the specified {@code long} value. |
| 1072 | * @since 1.5 |
| 1073 | */ |
| 1074 | public static int bitCount(long i) { |
| 1075 | // HD, Figure 5-14 |
| 1076 | i = i - ((i >>> 1) & 0x5555555555555555L); |
| 1077 | i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L); |
| 1078 | i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL; |
| 1079 | i = i + (i >>> 8); |
| 1080 | i = i + (i >>> 16); |
| 1081 | i = i + (i >>> 32); |
| 1082 | return (int)i & 0x7f; |
| 1083 | } |
| 1084 | |
| 1085 | /** |
| 1086 | * Returns the value obtained by rotating the two's complement binary |
| 1087 | * representation of the specified {@code long} value left by the |
| 1088 | * specified number of bits. (Bits shifted out of the left hand, or |
| 1089 | * high-order, side reenter on the right, or low-order.) |
| 1090 | * |
| 1091 | * <p>Note that left rotation with a negative distance is equivalent to |
| 1092 | * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val, |
| 1093 | * distance)}. Note also that rotation by any multiple of 64 is a |
| 1094 | * no-op, so all but the last six bits of the rotation distance can be |
| 1095 | * ignored, even if the distance is negative: {@code rotateLeft(val, |
| 1096 | * distance) == rotateLeft(val, distance & 0x3F)}. |
| 1097 | * |
| 1098 | * @return the value obtained by rotating the two's complement binary |
| 1099 | * representation of the specified {@code long} value left by the |
| 1100 | * specified number of bits. |
| 1101 | * @since 1.5 |
| 1102 | */ |
| 1103 | public static long rotateLeft(long i, int distance) { |
| 1104 | return (i << distance) | (i >>> -distance); |
| 1105 | } |
| 1106 | |
| 1107 | /** |
| 1108 | * Returns the value obtained by rotating the two's complement binary |
| 1109 | * representation of the specified {@code long} value right by the |
| 1110 | * specified number of bits. (Bits shifted out of the right hand, or |
| 1111 | * low-order, side reenter on the left, or high-order.) |
| 1112 | * |
| 1113 | * <p>Note that right rotation with a negative distance is equivalent to |
| 1114 | * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val, |
| 1115 | * distance)}. Note also that rotation by any multiple of 64 is a |
| 1116 | * no-op, so all but the last six bits of the rotation distance can be |
| 1117 | * ignored, even if the distance is negative: {@code rotateRight(val, |
| 1118 | * distance) == rotateRight(val, distance & 0x3F)}. |
| 1119 | * |
| 1120 | * @return the value obtained by rotating the two's complement binary |
| 1121 | * representation of the specified {@code long} value right by the |
| 1122 | * specified number of bits. |
| 1123 | * @since 1.5 |
| 1124 | */ |
| 1125 | public static long rotateRight(long i, int distance) { |
| 1126 | return (i >>> distance) | (i << -distance); |
| 1127 | } |
| 1128 | |
| 1129 | /** |
| 1130 | * Returns the value obtained by reversing the order of the bits in the |
| 1131 | * two's complement binary representation of the specified {@code long} |
| 1132 | * value. |
| 1133 | * |
| 1134 | * @return the value obtained by reversing order of the bits in the |
| 1135 | * specified {@code long} value. |
| 1136 | * @since 1.5 |
| 1137 | */ |
| 1138 | public static long reverse(long i) { |
| 1139 | // HD, Figure 7-1 |
| 1140 | i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L; |
| 1141 | i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L; |
| 1142 | i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL; |
| 1143 | i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL; |
| 1144 | i = (i << 48) | ((i & 0xffff0000L) << 16) | |
| 1145 | ((i >>> 16) & 0xffff0000L) | (i >>> 48); |
| 1146 | return i; |
| 1147 | } |
| 1148 | |
| 1149 | /** |
| 1150 | * Returns the signum function of the specified {@code long} value. (The |
| 1151 | * return value is -1 if the specified value is negative; 0 if the |
| 1152 | * specified value is zero; and 1 if the specified value is positive.) |
| 1153 | * |
| 1154 | * @return the signum function of the specified {@code long} value. |
| 1155 | * @since 1.5 |
| 1156 | */ |
| 1157 | public static int signum(long i) { |
| 1158 | // HD, Section 2-7 |
| 1159 | return (int) ((i >> 63) | (-i >>> 63)); |
| 1160 | } |
| 1161 | |
| 1162 | /** |
| 1163 | * Returns the value obtained by reversing the order of the bytes in the |
| 1164 | * two's complement representation of the specified {@code long} value. |
| 1165 | * |
| 1166 | * @return the value obtained by reversing the bytes in the specified |
| 1167 | * {@code long} value. |
| 1168 | * @since 1.5 |
| 1169 | */ |
| 1170 | public static long reverseBytes(long i) { |
| 1171 | i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL; |
| 1172 | return (i << 48) | ((i & 0xffff0000L) << 16) | |
| 1173 | ((i >>> 16) & 0xffff0000L) | (i >>> 48); |
| 1174 | } |
| 1175 | |
| 1176 | /** use serialVersionUID from JDK 1.0.2 for interoperability */ |
| 1177 | private static final long serialVersionUID = 4290774380558885855L; |
| 1178 | } |