1 /*
2 * Copyright (c) 1994, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import java.math.*;
29
30 /**
31 * The {@code Long} class wraps a value of the primitive type {@code
32 * long} in an object. An object of type {@code Long} contains a
33 * single field whose type is {@code long}.
34 *
35 * <p> In addition, this class provides several methods for converting
36 * a {@code long} to a {@code String} and a {@code String} to a {@code
37 * long}, as well as other constants and methods useful when dealing
38 * with a {@code long}.
39 *
40 * <p>Implementation note: The implementations of the "bit twiddling"
41 * methods (such as {@link #highestOneBit(long) highestOneBit} and
42 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
43 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
44 * Delight</i>, (Addison Wesley, 2002).
45 *
46 * @author Lee Boynton
47 * @author Arthur van Hoff
48 * @author Josh Bloch
49 * @author Joseph D. Darcy
50 * @since JDK1.0
51 */
52 public final class Long extends Number implements Comparable<Long> {
53 /**
54 * A constant holding the minimum value a {@code long} can
55 * have, -2<sup>63</sup>.
56 */
57 public static final long MIN_VALUE = 0x8000000000000000L;
58
59 /**
60 * A constant holding the maximum value a {@code long} can
61 * have, 2<sup>63</sup>-1.
62 */
63 public static final long MAX_VALUE = 0x7fffffffffffffffL;
64
65 /**
66 * The {@code Class} instance representing the primitive type
67 * {@code long}.
68 *
69 * @since JDK1.1
70 */
71 @SuppressWarnings("unchecked")
72 public static final Class<Long> TYPE = (Class<Long>) Class.getPrimitiveClass("long");
73
74 /**
75 * Returns a string representation of the first argument in the
76 * radix specified by the second argument.
77 *
78 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
79 * or larger than {@code Character.MAX_RADIX}, then the radix
80 * {@code 10} is used instead.
81 *
82 * <p>If the first argument is negative, the first element of the
83 * result is the ASCII minus sign {@code '-'}
84 * (<code>'\u002d'</code>). If the first argument is not
85 * negative, no sign character appears in the result.
86 *
87 * <p>The remaining characters of the result represent the magnitude
88 * of the first argument. If the magnitude is zero, it is
89 * represented by a single zero character {@code '0'}
90 * (<code>'\u0030'</code>); otherwise, the first character of
91 * the representation of the magnitude will not be the zero
92 * character. The following ASCII characters are used as digits:
93 *
94 * <blockquote>
95 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
96 * </blockquote>
97 *
98 * These are <code>'\u0030'</code> through
99 * <code>'\u0039'</code> and <code>'\u0061'</code> through
100 * <code>'\u007a'</code>. If {@code radix} is
101 * <var>N</var>, then the first <var>N</var> of these characters
102 * are used as radix-<var>N</var> digits in the order shown. Thus,
103 * the digits for hexadecimal (radix 16) are
104 * {@code 0123456789abcdef}. If uppercase letters are
105 * desired, the {@link java.lang.String#toUpperCase()} method may
106 * be called on the result:
107 *
108 * <blockquote>
109 * {@code Long.toString(n, 16).toUpperCase()}
110 * </blockquote>
111 *
112 * @param i a {@code long} to be converted to a string.
113 * @param radix the radix to use in the string representation.
114 * @return a string representation of the argument in the specified radix.
115 * @see java.lang.Character#MAX_RADIX
116 * @see java.lang.Character#MIN_RADIX
117 */
118 public static String toString(long i, int radix) {
119 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
120 radix = 10;
121 if (radix == 10)
122 return toString(i);
123 char[] buf = new char[65];
124 int charPos = 64;
125 boolean negative = (i < 0);
126
127 if (!negative) {
128 i = -i;
129 }
130
131 while (i <= -radix) {
132 buf[charPos--] = Integer.digits[(int)(-(i % radix))];
133 i = i / radix;
134 }
135 buf[charPos] = Integer.digits[(int)(-i)];
136
137 if (negative) {
138 buf[--charPos] = '-';
139 }
140
141 return new String(buf, charPos, (65 - charPos));
142 }
143
144 /**
145 * Returns an unsigned string representation of the first argument
146 * in the radix specified by the second argument.
147 *
148 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
149 * or larger than {@code Character.MAX_RADIX}, then the radix
150 * {@code 10} is used instead.
151 *
152 * <p>Note that since the first argument is treated as an unsigned
153 * value, no leading sign character is printed.
154 *
155 * <p>If the magnitude is zero, it is represented by a single zero
156 * character {@code '0'} (<code>'\u0030'</code>); otherwise,
157 * the first character of the representation of the magnitude will
158 * not be the zero character.
159 *
160 * <p>The characters used as digits and the behavior of radixes
161 * is the same as {@link #toString(long, int) toString}.
162 *
163 * @param i an integer to be converted to an unsigned string.
164 * @param radix the radix to use in the string representation.
165 * @return an unsigned string representation of the argument in the specified radix.
166 * @see #toString(long, int)
167 * @since 1.8
168 */
169 public static String toUnsignedString(long i, int radix) {
170 if (i >= 0)
171 return toString(i, radix);
172 else {
173 switch (radix) {
174 case 2:
175 return toBinaryString(i);
176
177 case 4:
178 return toUnsignedString0(i, 2);
179
180 case 8:
181 return toOctalString(i);
182
183 case 10:
184 /*
185 * We can get the effect of an unsigned division by 10
186 * on a long value by first shifting right, yielding a
187 * positive value, and then dividing by 5. This
188 * allows the last digit and preceding digits to be
189 * isolated more quickly than by an initial conversion
190 * to BigInteger.
191 */
192 long quot = (i >>> 1) / 5;
193 long rem = i - quot * 10;
194 return toString(quot) + rem;
195
196 case 16:
197 return toHexString(i);
198
199 case 32:
200 return toUnsignedString0(i, 5);
201
202 default:
203 return toUnsignedBigInteger(i).toString(radix);
204 }
205 }
206 }
207
208 /**
209 * Return a BigInteger equal to the unsigned value of the
210 * argument.
211 */
212 private static BigInteger toUnsignedBigInteger(long i) {
213 int upper = (int) ((i >> 32) & 0xffffffff);
214 int lower = (int) i;
215
216 // return (upper << 32) + lower
217 return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
218 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
219 }
220
221 /**
222 * Returns a string representation of the {@code long}
223 * argument as an unsigned integer in base 16.
224 *
225 * <p>The unsigned {@code long} value is the argument plus
226 * 2<sup>64</sup> if the argument is negative; otherwise, it is
227 * equal to the argument. This value is converted to a string of
228 * ASCII digits in hexadecimal (base 16) with no extra
229 * leading {@code 0}s.
230 *
231 * <p>The value of the argument can be recovered from the returned
232 * string {@code s} by calling {@link
233 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
234 * 16)}.
235 *
236 * <p>If the unsigned magnitude is zero, it is represented by a
237 * single zero character {@code '0'} (<code>'\u0030'</code>);
238 * otherwise, the first character of the representation of the
239 * unsigned magnitude will not be the zero character. The
240 * following characters are used as hexadecimal digits:
241 *
242 * <blockquote>
243 * {@code 0123456789abcdef}
244 * </blockquote>
245 *
246 * These are the characters <code>'\u0030'</code> through
247 * <code>'\u0039'</code> and <code>'\u0061'</code> through
248 * <code>'\u0066'</code>. If uppercase letters are desired,
249 * the {@link java.lang.String#toUpperCase()} method may be called
250 * on the result:
251 *
252 * <blockquote>
253 * {@code Long.toHexString(n).toUpperCase()}
254 * </blockquote>
255 *
256 * @param i a {@code long} to be converted to a string.
257 * @return the string representation of the unsigned {@code long}
258 * value represented by the argument in hexadecimal
259 * (base 16).
260 * @see #parseUnsignedLong(String, int)
261 * @see #toUnsignedString(long, int)
262 * @since JDK 1.0.2
263 */
264 public static String toHexString(long i) {
265 return toUnsignedString0(i, 4);
266 }
267
268 /**
269 * Returns a string representation of the {@code long}
270 * argument as an unsigned integer in base 8.
271 *
272 * <p>The unsigned {@code long} value is the argument plus
273 * 2<sup>64</sup> if the argument is negative; otherwise, it is
274 * equal to the argument. This value is converted to a string of
275 * ASCII digits in octal (base 8) with no extra leading
276 * {@code 0}s.
277 *
278 * <p>The value of the argument can be recovered from the returned
279 * string {@code s} by calling {@link
280 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
281 * 8)}.
282 *
283 * <p>If the unsigned magnitude is zero, it is represented by a
284 * single zero character {@code '0'} (<code>'\u0030'</code>);
285 * otherwise, the first character of the representation of the
286 * unsigned magnitude will not be the zero character. The
287 * following characters are used as octal digits:
288 *
289 * <blockquote>
290 * {@code 01234567}
291 * </blockquote>
292 *
293 * These are the characters <code>'\u0030'</code> through
294 * <code>'\u0037'</code>.
295 *
296 * @param i a {@code long} to be converted to a string.
297 * @return the string representation of the unsigned {@code long}
298 * value represented by the argument in octal (base 8).
299 * @see #parseUnsignedLong(String, int)
300 * @see #toUnsignedString(long, int)
301 * @since JDK 1.0.2
302 */
303 public static String toOctalString(long i) {
304 return toUnsignedString0(i, 3);
305 }
306
307 /**
308 * Returns a string representation of the {@code long}
309 * argument as an unsigned integer in base 2.
310 *
311 * <p>The unsigned {@code long} value is the argument plus
312 * 2<sup>64</sup> if the argument is negative; otherwise, it is
313 * equal to the argument. This value is converted to a string of
314 * ASCII digits in binary (base 2) with no extra leading
315 * {@code 0}s.
316 *
317 * <p>The value of the argument can be recovered from the returned
318 * string {@code s} by calling {@link
319 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
320 * 2)}.
321 *
322 * <p>If the unsigned magnitude is zero, it is represented by a
323 * single zero character {@code '0'} (<code>'\u0030'</code>);
324 * otherwise, the first character of the representation of the
325 * unsigned magnitude will not be the zero character. The
326 * characters {@code '0'} (<code>'\u0030'</code>) and {@code
327 * '1'} (<code>'\u0031'</code>) are used as binary digits.
328 *
329 * @param i a {@code long} to be converted to a string.
330 * @return the string representation of the unsigned {@code long}
331 * value represented by the argument in binary (base 2).
332 * @see #parseUnsignedLong(String, int)
333 * @see #toUnsignedString(long, int)
334 * @since JDK 1.0.2
335 */
336 public static String toBinaryString(long i) {
337 return toUnsignedString0(i, 1);
338 }
339
340 /**
341 * Convert the integer to an unsigned number.
342 */
343 private static String toUnsignedString0(long i, int shift) {
344 char[] buf = new char[64];
345 int charPos = 64;
346 int radix = 1 << shift;
347 long mask = radix - 1;
348 do {
349 buf[--charPos] = Integer.digits[(int)(i & mask)];
350 i >>>= shift;
351 } while (i != 0);
352 return new String(buf, charPos, (64 - charPos));
353 }
354
355 /**
356 * Returns a {@code String} object representing the specified
357 * {@code long}. The argument is converted to signed decimal
358 * representation and returned as a string, exactly as if the
359 * argument and the radix 10 were given as arguments to the {@link
360 * #toString(long, int)} method.
361 *
362 * @param i a {@code long} to be converted.
363 * @return a string representation of the argument in base 10.
364 */
365 public static String toString(long i) {
366 if (i == Long.MIN_VALUE)
367 return "-9223372036854775808";
368 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
369 char[] buf = new char[size];
370 getChars(i, size, buf);
371 return new String(0, size, buf);
372 }
373
374 /**
375 * Returns an unsigned string representation of the argument.
376 *
377 * The argument is converted to unsigned decimal representation
378 * and returned as a string exactly as if the argument and radix
379 * 10 were given as arguments to the {@link #toUnsignedString(long,
380 * int)} method.
381 *
382 * @param i an integer to be converted to an unsigned string.
383 * @return an unsigned string representation of the argument.
384 * @see #toUnsignedString(long, int)
385 * @since 1.8
386 */
387 public static String toUnsignedString(long i) {
388 return toUnsignedString(i, 10);
389 }
390
391 /**
392 * Places characters representing the integer i into the
393 * character array buf. The characters are placed into
394 * the buffer backwards starting with the least significant
395 * digit at the specified index (exclusive), and working
396 * backwards from there.
397 *
398 * Will fail if i == Long.MIN_VALUE
399 */
400 static void getChars(long i, int index, char[] buf) {
401 long q;
402 int r;
403 int charPos = index;
404 char sign = 0;
405
406 if (i < 0) {
407 sign = '-';
408 i = -i;
409 }
410
411 // Get 2 digits/iteration using longs until quotient fits into an int
412 while (i > Integer.MAX_VALUE) {
413 q = i / 100;
414 // really: r = i - (q * 100);
415 r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
416 i = q;
417 buf[--charPos] = Integer.DigitOnes[r];
418 buf[--charPos] = Integer.DigitTens[r];
419 }
420
421 // Get 2 digits/iteration using ints
422 int q2;
423 int i2 = (int)i;
424 while (i2 >= 65536) {
425 q2 = i2 / 100;
426 // really: r = i2 - (q * 100);
427 r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
428 i2 = q2;
429 buf[--charPos] = Integer.DigitOnes[r];
430 buf[--charPos] = Integer.DigitTens[r];
431 }
432
433 // Fall thru to fast mode for smaller numbers
434 // assert(i2 <= 65536, i2);
435 for (;;) {
436 q2 = (i2 * 52429) >>> (16+3);
437 r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
438 buf[--charPos] = Integer.digits[r];
439 i2 = q2;
440 if (i2 == 0) break;
441 }
442 if (sign != 0) {
443 buf[--charPos] = sign;
444 }
445 }
446
447 // Requires positive x
448 static int stringSize(long x) {
449 long p = 10;
450 for (int i=1; i<19; i++) {
451 if (x < p)
452 return i;
453 p = 10*p;
454 }
455 return 19;
456 }
457
458 /**
459 * Parses the string argument as a signed {@code long} in the
460 * radix specified by the second argument. The characters in the
461 * string must all be digits of the specified radix (as determined
462 * by whether {@link java.lang.Character#digit(char, int)} returns
463 * a nonnegative value), except that the first character may be an
464 * ASCII minus sign {@code '-'} (<code>'\u002D'</code>) to
465 * indicate a negative value or an ASCII plus sign {@code '+'}
466 * (<code>'\u002B'</code>) to indicate a positive value. The
467 * resulting {@code long} value is returned.
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 - except that either
474 * {@code L} or {@code l} may appear as a digit for a
475 * radix greater than 22.
476 *
477 * <p>An exception of type {@code NumberFormatException} is
478 * thrown if any of the following situations occurs:
479 * <ul>
480 *
481 * <li>The first argument is {@code null} or is a string of
482 * length zero.
483 *
484 * <li>The {@code radix} is either smaller than {@link
485 * java.lang.Character#MIN_RADIX} or larger than {@link
486 * java.lang.Character#MAX_RADIX}.
487 *
488 * <li>Any character of the string is not a digit of the specified
489 * radix, except that the first character may be a minus sign
490 * {@code '-'} (<code>'\u002d'</code>) or plus sign {@code
491 * '+'} (<code>'\u002B'</code>) provided that the string is
492 * longer than length 1.
493 *
494 * <li>The value represented by the string is not a value of type
495 * {@code long}.
496 * </ul>
497 *
498 * <p>Examples:
499 * <blockquote><pre>
500 * parseLong("0", 10) returns 0L
501 * parseLong("473", 10) returns 473L
502 * parseLong("+42", 10) returns 42L
503 * parseLong("-0", 10) returns 0L
504 * parseLong("-FF", 16) returns -255L
505 * parseLong("1100110", 2) returns 102L
506 * parseLong("99", 8) throws a NumberFormatException
507 * parseLong("Hazelnut", 10) throws a NumberFormatException
508 * parseLong("Hazelnut", 36) returns 1356099454469L
509 * </pre></blockquote>
510 *
511 * @param s the {@code String} containing the
512 * {@code long} representation to be parsed.
513 * @param radix the radix to be used while parsing {@code s}.
514 * @return the {@code long} represented by the string argument in
515 * the specified radix.
516 * @throws NumberFormatException if the string does not contain a
517 * parsable {@code long}.
518 */
519 public static long parseLong(String s, int radix)
520 throws NumberFormatException
521 {
522 if (s == null) {
523 throw new NumberFormatException("null");
524 }
525
526 if (radix < Character.MIN_RADIX) {
527 throw new NumberFormatException("radix " + radix +
528 " less than Character.MIN_RADIX");
529 }
530 if (radix > Character.MAX_RADIX) {
531 throw new NumberFormatException("radix " + radix +
532 " greater than Character.MAX_RADIX");
533 }
534
535 long result = 0;
536 boolean negative = false;
537 int i = 0, len = s.length();
538 long limit = -Long.MAX_VALUE;
539 long multmin;
540 int digit;
541
542 if (len > 0) {
543 char firstChar = s.charAt(0);
544 if (firstChar < '0') { // Possible leading "+" or "-"
545 if (firstChar == '-') {
546 negative = true;
547 limit = Long.MIN_VALUE;
548 } else if (firstChar != '+')
549 throw NumberFormatException.forInputString(s);
550
551 if (len == 1) // Cannot have lone "+" or "-"
552 throw NumberFormatException.forInputString(s);
553 i++;
554 }
555 multmin = limit / radix;
556 while (i < len) {
557 // Accumulating negatively avoids surprises near MAX_VALUE
558 digit = Character.digit(s.charAt(i++),radix);
559 if (digit < 0) {
560 throw NumberFormatException.forInputString(s);
561 }
562 if (result < multmin) {
563 throw NumberFormatException.forInputString(s);
564 }
565 result *= radix;
566 if (result < limit + digit) {
567 throw NumberFormatException.forInputString(s);
568 }
569 result -= digit;
570 }
571 } else {
572 throw NumberFormatException.forInputString(s);
573 }
574 return negative ? result : -result;
575 }
576
577 /**
578 * Parses the string argument as a signed decimal {@code long}.
579 * The characters in the string must all be decimal digits, except
580 * that the first character may be an ASCII minus sign {@code '-'}
581 * (<code>\u002D'</code>) to indicate a negative value or an
582 * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to
583 * indicate a positive value. The resulting {@code long} value is
584 * returned, exactly as if the argument and the radix {@code 10}
585 * were given as arguments to the {@link
586 * #parseLong(java.lang.String, int)} method.
587 *
588 * <p>Note that neither the character {@code L}
589 * (<code>'\u004C'</code>) nor {@code l}
590 * (<code>'\u006C'</code>) is permitted to appear at the end
591 * of the string as a type indicator, as would be permitted in
592 * Java programming language source code.
593 *
594 * @param s a {@code String} containing the {@code long}
595 * representation to be parsed
596 * @return the {@code long} represented by the argument in
597 * decimal.
598 * @throws NumberFormatException if the string does not contain a
599 * parsable {@code long}.
600 */
601 public static long parseLong(String s) throws NumberFormatException {
602 return parseLong(s, 10);
603 }
604
605 /**
606 * Parses the string argument as an unsigned integer in the radix
607 * specified by the second argument.
608 *
609 * The characters in the string must all be digits of the
610 * specified radix (as determined by whether {@link
611 * java.lang.Character#digit(char, int)} returns a nonnegative
612 * value), except that the first character may be an ASCII plus
613 * sign {@code '+'} (<code>'\u002B'</code>). The resulting
614 * integer value is returned.
615 *
616 * <p>An exception of type {@code NumberFormatException} is
617 * thrown if any of the following situations occurs:
618 * <ul>
619 * <li>The first argument is {@code null} or is a string of
620 * length zero.
621 *
622 * <li>The radix is either smaller than
623 * {@link java.lang.Character#MIN_RADIX} or
624 * larger than {@link java.lang.Character#MAX_RADIX}.
625 *
626 * <li>Any character of the string is not a digit of the specified
627 * radix, except that the first character may be a plus sign
628 * {@code '+'} (<code>'\u002B'</code>) provided that the
629 * string is longer than length 1.
630 *
631 * <li>The value represented by the string is larger than the
632 * largest unsigned {@code long}, 2<sup>64</sup>-1.
633 *
634 * </ul>
635 *
636 *
637 * @param s the {@code String} containing the unsigned integer
638 * representation to be parsed
639 * @param radix the radix to be used while parsing {@code s}.
640 * @return the integer represented by the string argument in the
641 * specified radix.
642 * @throws NumberFormatException if the {@code String}
643 * does not contain a parsable {@code long}.
644 * @since 1.8
645 */
646 public static long parseUnsignedLong(String s, int radix)
647 throws NumberFormatException {
648 if (s == null) {
649 throw new NumberFormatException("null");
650 }
651
652 int len = s.length();
653 if (len > 0) {
654 char firstChar = s.charAt(0);
655 if (firstChar == '-') {
656 throw new
657 NumberFormatException(String.format("Illegal leading minus sign " +
658 "on unsigned string %s.", s));
659 } else {
660 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
661 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
662 return parseLong(s, radix);
663 }
664
665 // For simplicty, use BigInteger for parsing
666 BigInteger bi = new BigInteger(s, radix);
667
668 // Largest *unsigned* value is all ones in binary
669 BigInteger limit = toUnsignedBigInteger(-1L);
670
671 if (bi.compareTo(limit) <= 0) {
672 return bi.longValue();
673 } else {
674 throw new
675 NumberFormatException(String.format("String value %s exceeds " +
676 "range of unsigned long.", s));
677 }
678 }
679 } else {
680 throw NumberFormatException.forInputString(s);
681 }
682 }
683
684 /**
685 * Parses the string argument as an unsigned decimal integer. The
686 * characters in the string must all be decimal digits, except
687 * that the first character may be an an ASCII plus sign {@code
688 * '+'} (<code>'\u002B'</code>). The resulting integer value
689 * is returned, exactly as if the argument and the radix 10 were
690 * given as arguments to the {@link
691 * #parseUnsignedLong(java.lang.String, int)} method.
692 *
693 * @param s a {@code String} containing the unsigned {@code long}
694 * representation to be parsed
695 * @return the unsigned integer value represented by the argument in decimal.
696 * @throws NumberFormatException if the string does not contain a
697 * parsable unsigned integer.
698 * @since 1.8
699 */
700 public static long parseUnsignedLong(String s) throws NumberFormatException {
701 return parseUnsignedLong(s, 10);
702 }
703
704 /**
705 * Returns a {@code Long} object holding the value
706 * extracted from the specified {@code String} when parsed
707 * with the radix given by the second argument. The first
708 * argument is interpreted as representing a signed
709 * {@code long} in the radix specified by the second
710 * argument, exactly as if the arguments were given to the {@link
711 * #parseLong(java.lang.String, int)} method. The result is a
712 * {@code Long} object that represents the {@code long}
713 * value specified by the string.
714 *
715 * <p>In other words, this method returns a {@code Long} object equal
716 * to the value of:
717 *
718 * <blockquote>
719 * {@code new Long(Long.parseLong(s, radix))}
720 * </blockquote>
721 *
722 * @param s the string to be parsed
723 * @param radix the radix to be used in interpreting {@code s}
724 * @return a {@code Long} object holding the value
725 * represented by the string argument in the specified
726 * radix.
727 * @throws NumberFormatException If the {@code String} does not
728 * contain a parsable {@code long}.
729 */
730 public static Long valueOf(String s, int radix) throws NumberFormatException {
731 return Long.valueOf(parseLong(s, radix));
732 }
733
734 /**
735 * Returns a {@code Long} object holding the value
736 * of the specified {@code String}. The argument is
737 * interpreted as representing a signed decimal {@code long},
738 * exactly as if the argument were given to the {@link
739 * #parseLong(java.lang.String)} method. The result is a
740 * {@code Long} object that represents the integer value
741 * specified by the string.
742 *
743 * <p>In other words, this method returns a {@code Long} object
744 * equal to the value of:
745 *
746 * <blockquote>
747 * {@code new Long(Long.parseLong(s))}
748 * </blockquote>
749 *
750 * @param s the string to be parsed.
751 * @return a {@code Long} object holding the value
752 * represented by the string argument.
753 * @throws NumberFormatException If the string cannot be parsed
754 * as a {@code long}.
755 */
756 public static Long valueOf(String s) throws NumberFormatException
757 {
758 return Long.valueOf(parseLong(s, 10));
759 }
760
761 private static class LongCache {
762 private LongCache(){}
763
764 static final Long cache[] = new Long[-(-128) + 127 + 1];
765
766 static {
767 for(int i = 0; i < cache.length; i++)
768 cache[i] = new Long(i - 128);
769 }
770 }
771
772 /**
773 * Returns a {@code Long} instance representing the specified
774 * {@code long} value.
775 * If a new {@code Long} instance is not required, this method
776 * should generally be used in preference to the constructor
777 * {@link #Long(long)}, as this method is likely to yield
778 * significantly better space and time performance by caching
779 * frequently requested values.
780 *
781 * Note that unlike the {@linkplain Integer#valueOf(int)
782 * corresponding method} in the {@code Integer} class, this method
783 * is <em>not</em> required to cache values within a particular
784 * range.
785 *
786 * @param l a long value.
787 * @return a {@code Long} instance representing {@code l}.
788 * @since 1.5
789 */
790 public static Long valueOf(long l) {
791 final int offset = 128;
792 if (l >= -128 && l <= 127) { // will cache
793 return LongCache.cache[(int)l + offset];
794 }
795 return new Long(l);
796 }
797
798 /**
799 * Decodes a {@code String} into a {@code Long}.
800 * Accepts decimal, hexadecimal, and octal numbers given by the
801 * following grammar:
802 *
803 * <blockquote>
804 * <dl>
805 * <dt><i>DecodableString:</i>
806 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
807 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
808 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
809 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
810 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
811 * <p>
812 * <dt><i>Sign:</i>
813 * <dd>{@code -}
814 * <dd>{@code +}
815 * </dl>
816 * </blockquote>
817 *
818 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
819 * are as defined in section 3.10.1 of
820 * <cite>The Java™ Language Specification</cite>,
821 * except that underscores are not accepted between digits.
822 *
823 * <p>The sequence of characters following an optional
824 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
825 * "{@code #}", or leading zero) is parsed as by the {@code
826 * Long.parseLong} method with the indicated radix (10, 16, or 8).
827 * This sequence of characters must represent a positive value or
828 * a {@link NumberFormatException} will be thrown. The result is
829 * negated if first character of the specified {@code String} is
830 * the minus sign. No whitespace characters are permitted in the
831 * {@code String}.
832 *
833 * @param nm the {@code String} to decode.
834 * @return a {@code Long} object holding the {@code long}
835 * value represented by {@code nm}
836 * @throws NumberFormatException if the {@code String} does not
837 * contain a parsable {@code long}.
838 * @see java.lang.Long#parseLong(String, int)
839 * @since 1.2
840 */
841 public static Long decode(String nm) throws NumberFormatException {
842 int radix = 10;
843 int index = 0;
844 boolean negative = false;
845 Long result;
846
847 if (nm.length() == 0)
848 throw new NumberFormatException("Zero length string");
849 char firstChar = nm.charAt(0);
850 // Handle sign, if present
851 if (firstChar == '-') {
852 negative = true;
853 index++;
854 } else if (firstChar == '+')
855 index++;
856
857 // Handle radix specifier, if present
858 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
859 index += 2;
860 radix = 16;
861 }
862 else if (nm.startsWith("#", index)) {
863 index ++;
864 radix = 16;
865 }
866 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
867 index ++;
868 radix = 8;
869 }
870
871 if (nm.startsWith("-", index) || nm.startsWith("+", index))
872 throw new NumberFormatException("Sign character in wrong position");
873
874 try {
875 result = Long.valueOf(nm.substring(index), radix);
876 result = negative ? Long.valueOf(-result.longValue()) : result;
877 } catch (NumberFormatException e) {
878 // If number is Long.MIN_VALUE, we'll end up here. The next line
879 // handles this case, and causes any genuine format error to be
880 // rethrown.
881 String constant = negative ? ("-" + nm.substring(index))
882 : nm.substring(index);
883 result = Long.valueOf(constant, radix);
884 }
885 return result;
886 }
887
888 /**
889 * The value of the {@code Long}.
890 *
891 * @serial
892 */
893 private final long value;
894
895 /**
896 * Constructs a newly allocated {@code Long} object that
897 * represents the specified {@code long} argument.
898 *
899 * @param value the value to be represented by the
900 * {@code Long} object.
901 */
902 public Long(long value) {
903 this.value = value;
904 }
905
906 /**
907 * Constructs a newly allocated {@code Long} object that
908 * represents the {@code long} value indicated by the
909 * {@code String} parameter. The string is converted to a
910 * {@code long} value in exactly the manner used by the
911 * {@code parseLong} method for radix 10.
912 *
913 * @param s the {@code String} to be converted to a
914 * {@code Long}.
915 * @throws NumberFormatException if the {@code String} does not
916 * contain a parsable {@code long}.
917 * @see java.lang.Long#parseLong(java.lang.String, int)
918 */
919 public Long(String s) throws NumberFormatException {
920 this.value = parseLong(s, 10);
921 }
922
923 /**
924 * Returns the value of this {@code Long} as a {@code byte} after
925 * a narrowing primitive conversion.
926 * @jls 5.1.3 Narrowing Primitive Conversions
927 */
928 public byte byteValue() {
929 return (byte)value;
930 }
931
932 /**
933 * Returns the value of this {@code Long} as a {@code short} after
934 * a narrowing primitive conversion.
935 * @jls 5.1.3 Narrowing Primitive Conversions
936 */
937 public short shortValue() {
938 return (short)value;
939 }
940
941 /**
942 * Returns the value of this {@code Long} as an {@code int} after
943 * a narrowing primitive conversion.
944 * @jls 5.1.3 Narrowing Primitive Conversions
945 */
946 public int intValue() {
947 return (int)value;
948 }
949
950 /**
951 * Returns the value of this {@code Long} as a
952 * {@code long} value.
953 */
954 public long longValue() {
955 return value;
956 }
957
958 /**
959 * Returns the value of this {@code Long} as a {@code float} after
960 * a widening primitive conversion.
961 * @jls 5.1.2 Widening Primitive Conversions
962 */
963 public float floatValue() {
964 return (float)value;
965 }
966
967 /**
968 * Returns the value of this {@code Long} as a {@code double}
969 * after a widening primitive conversion.
970 * @jls 5.1.2 Widening Primitive Conversions
971 */
972 public double doubleValue() {
973 return (double)value;
974 }
975
976 /**
977 * Returns a {@code String} object representing this
978 * {@code Long}'s value. The value is converted to signed
979 * decimal representation and returned as a string, exactly as if
980 * the {@code long} value were given as an argument to the
981 * {@link java.lang.Long#toString(long)} method.
982 *
983 * @return a string representation of the value of this object in
984 * base 10.
985 */
986 public String toString() {
987 return toString(value);
988 }
989
990 /**
991 * Returns a hash code for this {@code Long}. The result is
992 * the exclusive OR of the two halves of the primitive
993 * {@code long} value held by this {@code Long}
994 * object. That is, the hashcode is the value of the expression:
995 *
996 * <blockquote>
997 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
998 * </blockquote>
999 *
1000 * @return a hash code value for this object.
1001 */
1002 public int hashCode() {
1003 return (int)(value ^ (value >>> 32));
1004 }
1005
1006 /**
1007 * Compares this object to the specified object. The result is
1008 * {@code true} if and only if the argument is not
1009 * {@code null} and is a {@code Long} object that
1010 * contains the same {@code long} value as this object.
1011 *
1012 * @param obj the object to compare with.
1013 * @return {@code true} if the objects are the same;
1014 * {@code false} otherwise.
1015 */
1016 public boolean equals(Object obj) {
1017 if (obj instanceof Long) {
1018 return value == ((Long)obj).longValue();
1019 }
1020 return false;
1021 }
1022
1023 /**
1024 * Determines the {@code long} value of the system property
1025 * with the specified name.
1026 *
1027 * <p>The first argument is treated as the name of a system
1028 * property. System properties are accessible through the {@link
1029 * java.lang.System#getProperty(java.lang.String)} method. The
1030 * string value of this property is then interpreted as a {@code
1031 * long} value using the grammar supported by {@link Long#decode decode}
1032 * and a {@code Long} object representing this value is returned.
1033 *
1034 * <p>If there is no property with the specified name, if the
1035 * specified name is empty or {@code null}, or if the property
1036 * does not have the correct numeric format, then {@code null} is
1037 * returned.
1038 *
1039 * <p>In other words, this method returns a {@code Long} object
1040 * equal to the value of:
1041 *
1042 * <blockquote>
1043 * {@code getLong(nm, null)}
1044 * </blockquote>
1045 *
1046 * @param nm property name.
1047 * @return the {@code Long} value of the property.
1048 * @throws SecurityException for the same reasons as
1049 * {@link System#getProperty(String) System.getProperty}
1050 * @see java.lang.System#getProperty(java.lang.String)
1051 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1052 */
1053 public static Long getLong(String nm) {
1054 return getLong(nm, null);
1055 }
1056
1057 /**
1058 * Determines the {@code long} value of the system property
1059 * with the specified name.
1060 *
1061 * <p>The first argument is treated as the name of a system
1062 * property. System properties are accessible through the {@link
1063 * java.lang.System#getProperty(java.lang.String)} method. The
1064 * string value of this property is then interpreted as a {@code
1065 * long} value using the grammar supported by {@link Long#decode decode}
1066 * and a {@code Long} object representing this value is returned.
1067 *
1068 * <p>The second argument is the default value. A {@code Long} object
1069 * that represents the value of the second argument is returned if there
1070 * is no property of the specified name, if the property does not have
1071 * the correct numeric format, or if the specified name is empty or null.
1072 *
1073 * <p>In other words, this method returns a {@code Long} object equal
1074 * to the value of:
1075 *
1076 * <blockquote>
1077 * {@code getLong(nm, new Long(val))}
1078 * </blockquote>
1079 *
1080 * but in practice it may be implemented in a manner such as:
1081 *
1082 * <blockquote><pre>
1083 * Long result = getLong(nm, null);
1084 * return (result == null) ? new Long(val) : result;
1085 * </pre></blockquote>
1086 *
1087 * to avoid the unnecessary allocation of a {@code Long} object when
1088 * the default value is not needed.
1089 *
1090 * @param nm property name.
1091 * @param val default value.
1092 * @return the {@code Long} value of the property.
1093 * @throws SecurityException for the same reasons as
1094 * {@link System#getProperty(String) System.getProperty}
1095 * @see java.lang.System#getProperty(java.lang.String)
1096 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1097 */
1098 public static Long getLong(String nm, long val) {
1099 Long result = Long.getLong(nm, null);
1100 return (result == null) ? Long.valueOf(val) : result;
1101 }
1102
1103 /**
1104 * Returns the {@code long} value of the system property with
1105 * the specified name. The first argument is treated as the name
1106 * of a system property. System properties are accessible through
1107 * the {@link java.lang.System#getProperty(java.lang.String)}
1108 * method. The string value of this property is then interpreted
1109 * as a {@code long} value, as per the
1110 * {@link Long#decode decode} method, and a {@code Long} object
1111 * representing this value is returned; in summary:
1112 *
1113 * <ul>
1114 * <li>If the property value begins with the two ASCII characters
1115 * {@code 0x} or the ASCII character {@code #}, not followed by
1116 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1117 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1118 * with radix 16.
1119 * <li>If the property value begins with the ASCII character
1120 * {@code 0} followed by another character, it is parsed as
1121 * an octal integer exactly as by the method {@link
1122 * #valueOf(java.lang.String, int)} with radix 8.
1123 * <li>Otherwise the property value is parsed as a decimal
1124 * integer exactly as by the method
1125 * {@link #valueOf(java.lang.String, int)} with radix 10.
1126 * </ul>
1127 *
1128 * <p>Note that, in every case, neither {@code L}
1129 * (<code>'\u004C'</code>) nor {@code l}
1130 * (<code>'\u006C'</code>) is permitted to appear at the end
1131 * of the property value as a type indicator, as would be
1132 * permitted in Java programming language source code.
1133 *
1134 * <p>The second argument is the default value. The default value is
1135 * returned if there is no property of the specified name, if the
1136 * property does not have the correct numeric format, or if the
1137 * specified name is empty or {@code null}.
1138 *
1139 * @param nm property name.
1140 * @param val default value.
1141 * @return the {@code Long} value of the property.
1142 * @throws SecurityException for the same reasons as
1143 * {@link System#getProperty(String) System.getProperty}
1144 * @see System#getProperty(java.lang.String)
1145 * @see System#getProperty(java.lang.String, java.lang.String)
1146 */
1147 public static Long getLong(String nm, Long val) {
1148 String v = null;
1149 try {
1150 v = System.getProperty(nm);
1151 } catch (IllegalArgumentException | NullPointerException e) {
1152 }
1153 if (v != null) {
1154 try {
1155 return Long.decode(v);
1156 } catch (NumberFormatException e) {
1157 }
1158 }
1159 return val;
1160 }
1161
1162 /**
1163 * Compares two {@code Long} objects numerically.
1164 *
1165 * @param anotherLong the {@code Long} to be compared.
1166 * @return the value {@code 0} if this {@code Long} is
1167 * equal to the argument {@code Long}; a value less than
1168 * {@code 0} if this {@code Long} is numerically less
1169 * than the argument {@code Long}; and a value greater
1170 * than {@code 0} if this {@code Long} is numerically
1171 * greater than the argument {@code Long} (signed
1172 * comparison).
1173 * @since 1.2
1174 */
1175 public int compareTo(Long anotherLong) {
1176 return compare(this.value, anotherLong.value);
1177 }
1178
1179 /**
1180 * Compares two {@code long} values numerically.
1181 * The value returned is identical to what would be returned by:
1182 * <pre>
1183 * Long.valueOf(x).compareTo(Long.valueOf(y))
1184 * </pre>
1185 *
1186 * @param x the first {@code long} to compare
1187 * @param y the second {@code long} to compare
1188 * @return the value {@code 0} if {@code x == y};
1189 * a value less than {@code 0} if {@code x < y}; and
1190 * a value greater than {@code 0} if {@code x > y}
1191 * @since 1.7
1192 */
1193 public static int compare(long x, long y) {
1194 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1195 }
1196
1197 /**
1198 * Compares two {@code long} values numerically treating the values
1199 * as unsigned.
1200 *
1201 * @param x the first {@code long} to compare
1202 * @param y the second {@code long} to compare
1203 * @return the value {@code 0} if {@code x == y}; a value less
1204 * than {@code 0} if {@code x < y} as unsigned values; and
1205 * a value greater than {@code 0} if {@code x > y} as
1206 * unsigned values
1207 * @since 1.8
1208 */
1209 public static int compareUnsigned(long x, long y) {
1210 return compare(x + MIN_VALUE, y + MIN_VALUE);
1211 }
1212
1213
1214 /**
1215 * Returns the unsigned quotient of dividing the first argument by
1216 * the second where each argument is interpreted as an unsigned
1217 * value.
1218 *
1219 * In other words, return the unsigned value of {@code
1220 * (dividend / divisor)}.
1221 *
1222 * @return the unsigned quotient of the first argument divided by
1223 * the second argument
1224 * @param dividend the value to be divided
1225 * @param divisor the value doing the dividing
1226 * @since 1.8
1227 */
1228 public static long divideUnsigned(long dividend, long divisor) {
1229 if (divisor < 0L) { // signed comparison
1230 // Answer must be 0 or 1 depending on relative magnitude
1231 // of dividiend and divisor.
1232 return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;
1233 }
1234
1235 /*
1236 * For simple code, leveraging BigInteger. Longer and faster
1237 * code written directly in terms of operations on longs is
1238 * possible; see "Hacker's Delight" for divide and remainder
1239 * algorithms.
1240 */
1241 return toUnsignedBigInteger(dividend).
1242 divide(toUnsignedBigInteger(divisor)).longValue();
1243 }
1244
1245 /**
1246 * Returns the unsigned remainder from dividing the first argument by
1247 * the second where each argument is interpreted as an unsigned
1248 * value.
1249 *
1250 * In other words, return the unsigned value of {@code
1251 * (dividend % divisor)}.
1252 *
1253 * @return the unsigned remainder of the first argument divided by
1254 * the second argument
1255 * @param dividend the value to be divided
1256 * @param divisor the value doing the dividing
1257 * @since 1.8
1258 */
1259 public static long remainderUnsigned(long dividend, long divisor) {
1260 return toUnsignedBigInteger(dividend).
1261 remainder(toUnsignedBigInteger(divisor)).longValue();
1262 }
1263
1264 // Bit Twiddling
1265
1266 /**
1267 * The number of bits used to represent a {@code long} value in two's
1268 * complement binary form.
1269 *
1270 * @since 1.5
1271 */
1272 public static final int SIZE = 64;
1273
1274 /**
1275 * Returns a {@code long} value with at most a single one-bit, in the
1276 * position of the highest-order ("leftmost") one-bit in the specified
1277 * {@code long} value. Returns zero if the specified value has no
1278 * one-bits in its two's complement binary representation, that is, if it
1279 * is equal to zero.
1280 *
1281 * @return a {@code long} value with a single one-bit, in the position
1282 * of the highest-order one-bit in the specified value, or zero if
1283 * the specified value is itself equal to zero.
1284 * @since 1.5
1285 */
1286 public static long highestOneBit(long i) {
1287 // HD, Figure 3-1
1288 i |= (i >> 1);
1289 i |= (i >> 2);
1290 i |= (i >> 4);
1291 i |= (i >> 8);
1292 i |= (i >> 16);
1293 i |= (i >> 32);
1294 return i - (i >>> 1);
1295 }
1296
1297 /**
1298 * Returns a {@code long} value with at most a single one-bit, in the
1299 * position of the lowest-order ("rightmost") one-bit in the specified
1300 * {@code long} value. Returns zero if the specified value has no
1301 * one-bits in its two's complement binary representation, that is, if it
1302 * is equal to zero.
1303 *
1304 * @return a {@code long} value with a single one-bit, in the position
1305 * of the lowest-order one-bit in the specified value, or zero if
1306 * the specified value is itself equal to zero.
1307 * @since 1.5
1308 */
1309 public static long lowestOneBit(long i) {
1310 // HD, Section 2-1
1311 return i & -i;
1312 }
1313
1314 /**
1315 * Returns the number of zero bits preceding the highest-order
1316 * ("leftmost") one-bit in the two's complement binary representation
1317 * of the specified {@code long} value. Returns 64 if the
1318 * specified value has no one-bits in its two's complement representation,
1319 * in other words if it is equal to zero.
1320 *
1321 * <p>Note that this method is closely related to the logarithm base 2.
1322 * For all positive {@code long} values x:
1323 * <ul>
1324 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1325 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1326 * </ul>
1327 *
1328 * @return the number of zero bits preceding the highest-order
1329 * ("leftmost") one-bit in the two's complement binary representation
1330 * of the specified {@code long} value, or 64 if the value
1331 * is equal to zero.
1332 * @since 1.5
1333 */
1334 public static int numberOfLeadingZeros(long i) {
1335 // HD, Figure 5-6
1336 if (i == 0)
1337 return 64;
1338 int n = 1;
1339 int x = (int)(i >>> 32);
1340 if (x == 0) { n += 32; x = (int)i; }
1341 if (x >>> 16 == 0) { n += 16; x <<= 16; }
1342 if (x >>> 24 == 0) { n += 8; x <<= 8; }
1343 if (x >>> 28 == 0) { n += 4; x <<= 4; }
1344 if (x >>> 30 == 0) { n += 2; x <<= 2; }
1345 n -= x >>> 31;
1346 return n;
1347 }
1348
1349 /**
1350 * Returns the number of zero bits following the lowest-order ("rightmost")
1351 * one-bit in the two's complement binary representation of the specified
1352 * {@code long} value. Returns 64 if the specified value has no
1353 * one-bits in its two's complement representation, in other words if it is
1354 * equal to zero.
1355 *
1356 * @return the number of zero bits following the lowest-order ("rightmost")
1357 * one-bit in the two's complement binary representation of the
1358 * specified {@code long} value, or 64 if the value is equal
1359 * to zero.
1360 * @since 1.5
1361 */
1362 public static int numberOfTrailingZeros(long i) {
1363 // HD, Figure 5-14
1364 int x, y;
1365 if (i == 0) return 64;
1366 int n = 63;
1367 y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
1368 y = x <<16; if (y != 0) { n = n -16; x = y; }
1369 y = x << 8; if (y != 0) { n = n - 8; x = y; }
1370 y = x << 4; if (y != 0) { n = n - 4; x = y; }
1371 y = x << 2; if (y != 0) { n = n - 2; x = y; }
1372 return n - ((x << 1) >>> 31);
1373 }
1374
1375 /**
1376 * Returns the number of one-bits in the two's complement binary
1377 * representation of the specified {@code long} value. This function is
1378 * sometimes referred to as the <i>population count</i>.
1379 *
1380 * @return the number of one-bits in the two's complement binary
1381 * representation of the specified {@code long} value.
1382 * @since 1.5
1383 */
1384 public static int bitCount(long i) {
1385 // HD, Figure 5-14
1386 i = i - ((i >>> 1) & 0x5555555555555555L);
1387 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1388 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1389 i = i + (i >>> 8);
1390 i = i + (i >>> 16);
1391 i = i + (i >>> 32);
1392 return (int)i & 0x7f;
1393 }
1394
1395 /**
1396 * Returns the value obtained by rotating the two's complement binary
1397 * representation of the specified {@code long} value left by the
1398 * specified number of bits. (Bits shifted out of the left hand, or
1399 * high-order, side reenter on the right, or low-order.)
1400 *
1401 * <p>Note that left rotation with a negative distance is equivalent to
1402 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1403 * distance)}. Note also that rotation by any multiple of 64 is a
1404 * no-op, so all but the last six bits of the rotation distance can be
1405 * ignored, even if the distance is negative: {@code rotateLeft(val,
1406 * distance) == rotateLeft(val, distance & 0x3F)}.
1407 *
1408 * @return the value obtained by rotating the two's complement binary
1409 * representation of the specified {@code long} value left by the
1410 * specified number of bits.
1411 * @since 1.5
1412 */
1413 public static long rotateLeft(long i, int distance) {
1414 return (i << distance) | (i >>> -distance);
1415 }
1416
1417 /**
1418 * Returns the value obtained by rotating the two's complement binary
1419 * representation of the specified {@code long} value right by the
1420 * specified number of bits. (Bits shifted out of the right hand, or
1421 * low-order, side reenter on the left, or high-order.)
1422 *
1423 * <p>Note that right rotation with a negative distance is equivalent to
1424 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1425 * distance)}. Note also that rotation by any multiple of 64 is a
1426 * no-op, so all but the last six bits of the rotation distance can be
1427 * ignored, even if the distance is negative: {@code rotateRight(val,
1428 * distance) == rotateRight(val, distance & 0x3F)}.
1429 *
1430 * @return the value obtained by rotating the two's complement binary
1431 * representation of the specified {@code long} value right by the
1432 * specified number of bits.
1433 * @since 1.5
1434 */
1435 public static long rotateRight(long i, int distance) {
1436 return (i >>> distance) | (i << -distance);
1437 }
1438
1439 /**
1440 * Returns the value obtained by reversing the order of the bits in the
1441 * two's complement binary representation of the specified {@code long}
1442 * value.
1443 *
1444 * @return the value obtained by reversing order of the bits in the
1445 * specified {@code long} value.
1446 * @since 1.5
1447 */
1448 public static long reverse(long i) {
1449 // HD, Figure 7-1
1450 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1451 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1452 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1453 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1454 i = (i << 48) | ((i & 0xffff0000L) << 16) |
1455 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1456 return i;
1457 }
1458
1459 /**
1460 * Returns the signum function of the specified {@code long} value. (The
1461 * return value is -1 if the specified value is negative; 0 if the
1462 * specified value is zero; and 1 if the specified value is positive.)
1463 *
1464 * @return the signum function of the specified {@code long} value.
1465 * @since 1.5
1466 */
1467 public static int signum(long i) {
1468 // HD, Section 2-7
1469 return (int) ((i >> 63) | (-i >>> 63));
1470 }
1471
1472 /**
1473 * Returns the value obtained by reversing the order of the bytes in the
1474 * two's complement representation of the specified {@code long} value.
1475 *
1476 * @return the value obtained by reversing the bytes in the specified
1477 * {@code long} value.
1478 * @since 1.5
1479 */
1480 public static long reverseBytes(long i) {
1481 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1482 return (i << 48) | ((i & 0xffff0000L) << 16) |
1483 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1484 }
1485
1486 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1487 private static final long serialVersionUID = 4290774380558885855L;
1488 }