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 a string representation of the first argument as an
146 * unsigned string 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 behavior of radixes and the characters used as digits
161 * are 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 if (i >= 0L)
214 return BigInteger.valueOf(i);
215 else {
216 int upper = (int) (i >>> 32);
217 int lower = (int) i;
218
219 // return (upper << 32) + lower
220 return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
221 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
222 }
223 }
224
225 /**
226 * Returns a string representation of the {@code long}
227 * argument as an unsigned integer in base 16.
228 *
229 * <p>The unsigned {@code long} value is the argument plus
230 * 2<sup>64</sup> if the argument is negative; otherwise, it is
231 * equal to the argument. This value is converted to a string of
232 * ASCII digits in hexadecimal (base 16) with no extra
233 * leading {@code 0}s.
234 *
235 * <p>The value of the argument can be recovered from the returned
236 * string {@code s} by calling {@link
237 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
238 * 16)}.
239 *
240 * <p>If the unsigned magnitude is zero, it is represented by a
241 * single zero character {@code '0'} (<code>'\u0030'</code>);
242 * otherwise, the first character of the representation of the
243 * unsigned magnitude will not be the zero character. The
244 * following characters are used as hexadecimal digits:
245 *
246 * <blockquote>
247 * {@code 0123456789abcdef}
248 * </blockquote>
249 *
250 * These are the characters <code>'\u0030'</code> through
251 * <code>'\u0039'</code> and <code>'\u0061'</code> through
252 * <code>'\u0066'</code>. If uppercase letters are desired,
253 * the {@link java.lang.String#toUpperCase()} method may be called
254 * on the result:
255 *
256 * <blockquote>
257 * {@code Long.toHexString(n).toUpperCase()}
258 * </blockquote>
259 *
260 * @param i a {@code long} to be converted to a string.
261 * @return the string representation of the unsigned {@code long}
262 * value represented by the argument in hexadecimal
263 * (base 16).
264 * @see #parseUnsignedLong(String, int)
265 * @see #toUnsignedString(long, int)
266 * @since JDK 1.0.2
267 */
268 public static String toHexString(long i) {
269 return toUnsignedString0(i, 4);
270 }
271
272 /**
273 * Returns a string representation of the {@code long}
274 * argument as an unsigned integer in base 8.
275 *
276 * <p>The unsigned {@code long} value is the argument plus
277 * 2<sup>64</sup> if the argument is negative; otherwise, it is
278 * equal to the argument. This value is converted to a string of
279 * ASCII digits in octal (base 8) with no extra leading
280 * {@code 0}s.
281 *
282 * <p>The value of the argument can be recovered from the returned
283 * string {@code s} by calling {@link
284 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
285 * 8)}.
286 *
287 * <p>If the unsigned magnitude is zero, it is represented by a
288 * single zero character {@code '0'} (<code>'\u0030'</code>);
289 * otherwise, the first character of the representation of the
290 * unsigned magnitude will not be the zero character. The
291 * following characters are used as octal digits:
292 *
293 * <blockquote>
294 * {@code 01234567}
295 * </blockquote>
296 *
297 * These are the characters <code>'\u0030'</code> through
298 * <code>'\u0037'</code>.
299 *
300 * @param i a {@code long} to be converted to a string.
301 * @return the string representation of the unsigned {@code long}
302 * value represented by the argument in octal (base 8).
303 * @see #parseUnsignedLong(String, int)
304 * @see #toUnsignedString(long, int)
305 * @since JDK 1.0.2
306 */
307 public static String toOctalString(long i) {
308 return toUnsignedString0(i, 3);
309 }
310
311 /**
312 * Returns a string representation of the {@code long}
313 * argument as an unsigned integer in base 2.
314 *
315 * <p>The unsigned {@code long} value is the argument plus
316 * 2<sup>64</sup> if the argument is negative; otherwise, it is
317 * equal to the argument. This value is converted to a string of
318 * ASCII digits in binary (base 2) with no extra leading
319 * {@code 0}s.
320 *
321 * <p>The value of the argument can be recovered from the returned
322 * string {@code s} by calling {@link
323 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
324 * 2)}.
325 *
326 * <p>If the unsigned magnitude is zero, it is represented by a
327 * single zero character {@code '0'} (<code>'\u0030'</code>);
328 * otherwise, the first character of the representation of the
329 * unsigned magnitude will not be the zero character. The
330 * characters {@code '0'} (<code>'\u0030'</code>) and {@code
331 * '1'} (<code>'\u0031'</code>) are used as binary digits.
332 *
333 * @param i a {@code long} to be converted to a string.
334 * @return the string representation of the unsigned {@code long}
335 * value represented by the argument in binary (base 2).
336 * @see #parseUnsignedLong(String, int)
337 * @see #toUnsignedString(long, int)
338 * @since JDK 1.0.2
339 */
340 public static String toBinaryString(long i) {
341 return toUnsignedString0(i, 1);
342 }
343
344 /**
345 * Convert the integer to an unsigned number.
346 */
347 private static String toUnsignedString0(long i, int shift) {
348 char[] buf = new char[64];
349 int charPos = 64;
350 int radix = 1 << shift;
351 long mask = radix - 1;
352 do {
353 buf[--charPos] = Integer.digits[(int)(i & mask)];
354 i >>>= shift;
355 } while (i != 0);
356 return new String(buf, charPos, (64 - charPos));
357 }
358
359 /**
360 * Returns a {@code String} object representing the specified
361 * {@code long}. The argument is converted to signed decimal
362 * representation and returned as a string, exactly as if the
363 * argument and the radix 10 were given as arguments to the {@link
364 * #toString(long, int)} method.
365 *
366 * @param i a {@code long} to be converted.
367 * @return a string representation of the argument in base 10.
368 */
369 public static String toString(long i) {
370 if (i == Long.MIN_VALUE)
371 return "-9223372036854775808";
372 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
373 char[] buf = new char[size];
374 getChars(i, size, buf);
375 return new String(0, size, buf);
376 }
377
378 /**
379 * Returns a string representation of the argument as an unsigned
380 * string.
381 *
382 * The argument is converted to unsigned decimal representation
383 * and returned as a string exactly as if the argument and radix
384 * 10 were given as arguments to the {@link #toUnsignedString(long,
385 * int)} method.
386 *
387 * @param i an integer to be converted to an unsigned string.
388 * @return an unsigned string representation of the argument.
389 * @see #toUnsignedString(long, int)
390 * @since 1.8
391 */
392 public static String toUnsignedString(long i) {
393 return toUnsignedString(i, 10);
394 }
395
396 /**
397 * Places characters representing the integer i into the
398 * character array buf. The characters are placed into
399 * the buffer backwards starting with the least significant
400 * digit at the specified index (exclusive), and working
401 * backwards from there.
402 *
403 * Will fail if i == Long.MIN_VALUE
404 */
405 static void getChars(long i, int index, char[] buf) {
406 long q;
407 int r;
408 int charPos = index;
409 char sign = 0;
410
411 if (i < 0) {
412 sign = '-';
413 i = -i;
414 }
415
416 // Get 2 digits/iteration using longs until quotient fits into an int
417 while (i > Integer.MAX_VALUE) {
418 q = i / 100;
419 // really: r = i - (q * 100);
420 r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
421 i = q;
422 buf[--charPos] = Integer.DigitOnes[r];
423 buf[--charPos] = Integer.DigitTens[r];
424 }
425
426 // Get 2 digits/iteration using ints
427 int q2;
428 int i2 = (int)i;
429 while (i2 >= 65536) {
430 q2 = i2 / 100;
431 // really: r = i2 - (q * 100);
432 r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
433 i2 = q2;
434 buf[--charPos] = Integer.DigitOnes[r];
435 buf[--charPos] = Integer.DigitTens[r];
436 }
437
438 // Fall thru to fast mode for smaller numbers
439 // assert(i2 <= 65536, i2);
440 for (;;) {
441 q2 = (i2 * 52429) >>> (16+3);
442 r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
443 buf[--charPos] = Integer.digits[r];
444 i2 = q2;
445 if (i2 == 0) break;
446 }
447 if (sign != 0) {
448 buf[--charPos] = sign;
449 }
450 }
451
452 // Requires positive x
453 static int stringSize(long x) {
454 long p = 10;
455 for (int i=1; i<19; i++) {
456 if (x < p)
457 return i;
458 p = 10*p;
459 }
460 return 19;
461 }
462
463 /**
464 * Parses the string argument as a signed {@code long} in the
465 * radix specified by the second argument. The characters in the
466 * string must all be digits of the specified radix (as determined
467 * by whether {@link java.lang.Character#digit(char, int)} returns
468 * a nonnegative value), except that the first character may be an
469 * ASCII minus sign {@code '-'} (<code>'\u002D'</code>) to
470 * indicate a negative value or an ASCII plus sign {@code '+'}
471 * (<code>'\u002B'</code>) to indicate a positive value. The
472 * resulting {@code long} value is returned.
473 *
474 * <p>Note that neither the character {@code L}
475 * (<code>'\u004C'</code>) nor {@code l}
476 * (<code>'\u006C'</code>) is permitted to appear at the end
477 * of the string as a type indicator, as would be permitted in
478 * Java programming language source code - except that either
479 * {@code L} or {@code l} may appear as a digit for a
480 * radix greater than 22.
481 *
482 * <p>An exception of type {@code NumberFormatException} is
483 * thrown if any of the following situations occurs:
484 * <ul>
485 *
486 * <li>The first argument is {@code null} or is a string of
487 * length zero.
488 *
489 * <li>The {@code radix} is either smaller than {@link
490 * java.lang.Character#MIN_RADIX} or larger than {@link
491 * java.lang.Character#MAX_RADIX}.
492 *
493 * <li>Any character of the string is not a digit of the specified
494 * radix, except that the first character may be a minus sign
495 * {@code '-'} (<code>'\u002d'</code>) or plus sign {@code
496 * '+'} (<code>'\u002B'</code>) provided that the string is
497 * longer than length 1.
498 *
499 * <li>The value represented by the string is not a value of type
500 * {@code long}.
501 * </ul>
502 *
503 * <p>Examples:
504 * <blockquote><pre>
505 * parseLong("0", 10) returns 0L
506 * parseLong("473", 10) returns 473L
507 * parseLong("+42", 10) returns 42L
508 * parseLong("-0", 10) returns 0L
509 * parseLong("-FF", 16) returns -255L
510 * parseLong("1100110", 2) returns 102L
511 * parseLong("99", 8) throws a NumberFormatException
512 * parseLong("Hazelnut", 10) throws a NumberFormatException
513 * parseLong("Hazelnut", 36) returns 1356099454469L
514 * </pre></blockquote>
515 *
516 * @param s the {@code String} containing the
517 * {@code long} representation to be parsed.
518 * @param radix the radix to be used while parsing {@code s}.
519 * @return the {@code long} represented by the string argument in
520 * the specified radix.
521 * @throws NumberFormatException if the string does not contain a
522 * parsable {@code long}.
523 */
524 public static long parseLong(String s, int radix)
525 throws NumberFormatException
526 {
527 if (s == null) {
528 throw new NumberFormatException("null");
529 }
530
531 if (radix < Character.MIN_RADIX) {
532 throw new NumberFormatException("radix " + radix +
533 " less than Character.MIN_RADIX");
534 }
535 if (radix > Character.MAX_RADIX) {
536 throw new NumberFormatException("radix " + radix +
537 " greater than Character.MAX_RADIX");
538 }
539
540 long result = 0;
541 boolean negative = false;
542 int i = 0, len = s.length();
543 long limit = -Long.MAX_VALUE;
544 long multmin;
545 int digit;
546
547 if (len > 0) {
548 char firstChar = s.charAt(0);
549 if (firstChar < '0') { // Possible leading "+" or "-"
550 if (firstChar == '-') {
551 negative = true;
552 limit = Long.MIN_VALUE;
553 } else if (firstChar != '+')
554 throw NumberFormatException.forInputString(s);
555
556 if (len == 1) // Cannot have lone "+" or "-"
557 throw NumberFormatException.forInputString(s);
558 i++;
559 }
560 multmin = limit / radix;
561 while (i < len) {
562 // Accumulating negatively avoids surprises near MAX_VALUE
563 digit = Character.digit(s.charAt(i++),radix);
564 if (digit < 0) {
565 throw NumberFormatException.forInputString(s);
566 }
567 if (result < multmin) {
568 throw NumberFormatException.forInputString(s);
569 }
570 result *= radix;
571 if (result < limit + digit) {
572 throw NumberFormatException.forInputString(s);
573 }
574 result -= digit;
575 }
576 } else {
577 throw NumberFormatException.forInputString(s);
578 }
579 return negative ? result : -result;
580 }
581
582 /**
583 * Parses the string argument as a signed decimal {@code long}.
584 * The characters in the string must all be decimal digits, except
585 * that the first character may be an ASCII minus sign {@code '-'}
586 * (<code>\u002D'</code>) to indicate a negative value or an
587 * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to
588 * indicate a positive value. The resulting {@code long} value is
589 * returned, exactly as if the argument and the radix {@code 10}
590 * were given as arguments to the {@link
591 * #parseLong(java.lang.String, int)} method.
592 *
593 * <p>Note that neither the character {@code L}
594 * (<code>'\u004C'</code>) nor {@code l}
595 * (<code>'\u006C'</code>) is permitted to appear at the end
596 * of the string as a type indicator, as would be permitted in
597 * Java programming language source code.
598 *
599 * @param s a {@code String} containing the {@code long}
600 * representation to be parsed
601 * @return the {@code long} represented by the argument in
602 * decimal.
603 * @throws NumberFormatException if the string does not contain a
604 * parsable {@code long}.
605 */
606 public static long parseLong(String s) throws NumberFormatException {
607 return parseLong(s, 10);
608 }
609
610 /**
611 * Parses the string argument as an unsigned {@code long} in the
612 * radix specified by the second argument. An unsigned integer
613 * maps the values usually associated with negative numbers to
614 * positive numbers larger than {@code MAX_VALUE}.
615 *
616 * The characters in the string must all be digits of the
617 * specified radix (as determined by whether {@link
618 * java.lang.Character#digit(char, int)} returns a nonnegative
619 * value), except that the first character may be an ASCII plus
620 * sign {@code '+'} (<code>'\u002B'</code>). The resulting
621 * integer value is returned.
622 *
623 * <p>An exception of type {@code NumberFormatException} is
624 * thrown if any of the following situations occurs:
625 * <ul>
626 * <li>The first argument is {@code null} or is a string of
627 * length zero.
628 *
629 * <li>The radix is either smaller than
630 * {@link java.lang.Character#MIN_RADIX} or
631 * larger than {@link java.lang.Character#MAX_RADIX}.
632 *
633 * <li>Any character of the string is not a digit of the specified
634 * radix, except that the first character may be a plus sign
635 * {@code '+'} (<code>'\u002B'</code>) provided that the
636 * string is longer than length 1.
637 *
638 * <li>The value represented by the string is larger than the
639 * largest unsigned {@code long}, 2<sup>64</sup>-1.
640 *
641 * </ul>
642 *
643 *
644 * @param s the {@code String} containing the unsigned integer
645 * representation to be parsed
646 * @param radix the radix to be used while parsing {@code s}.
647 * @return the integer represented by the string argument in the
648 * specified radix.
649 * @throws NumberFormatException if the {@code String}
650 * does not contain a parsable {@code long}.
651 * @since 1.8
652 */
653 public static long parseUnsignedLong(String s, int radix)
654 throws NumberFormatException {
655 if (s == null) {
656 throw new NumberFormatException("null");
657 }
658
659 int len = s.length();
660 if (len > 0) {
661 char firstChar = s.charAt(0);
662 if (firstChar == '-') {
663 throw new
664 NumberFormatException(String.format("Illegal leading minus sign " +
665 "on unsigned string %s.", s));
666 } else {
667 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
668 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
669 return parseLong(s, radix);
670 }
671
672 // No need for range checks on len due to testing above.
673 long first = parseLong(s.substring(0, len - 1), radix);
674 int second = Character.digit(s.charAt(len - 1), radix);
675 if (second < 0) {
676 throw new NumberFormatException("Bad digit at end of " + s);
677 }
678 long result = first * radix + second;
679 if (compareUnsigned(result, first) < 0) {
680 /*
681 * The maximum unsigned value, (2^64)-1, takes at
682 * most one more digit to represent than the
683 * maximum signed value, (2^63)-1. Therefore,
684 * parsing (len - 1) digits will be appropriately
685 * in-range of the signed parsing. In other
686 * words, if parsing (len -1) digits overflows
687 * signed parsing, parsing len digits will
688 * certainly overflow unsigned parsing.
689 *
690 * The compareUnsigned check above catches
691 * situations where an unsigned overflow occurs
692 * incorporating the contribution of the final
693 * digit.
694 */
695 throw new NumberFormatException(String.format("String value %s exceeds " +
696 "range of unsigned long.", s));
697 }
698 return result;
699 }
700 } else {
701 throw NumberFormatException.forInputString(s);
702 }
703 }
704
705 /**
706 * Parses the string argument as an unsigned decimal {@code long}. The
707 * characters in the string must all be decimal digits, except
708 * that the first character may be an an ASCII plus sign {@code
709 * '+'} (<code>'\u002B'</code>). The resulting integer value
710 * is returned, exactly as if the argument and the radix 10 were
711 * given as arguments to the {@link
712 * #parseUnsignedLong(java.lang.String, int)} method.
713 *
714 * @param s a {@code String} containing the unsigned {@code long}
715 * representation to be parsed
716 * @return the unsigned integer value represented by the argument in decimal.
717 * @throws NumberFormatException if the string does not contain a
718 * parsable unsigned integer.
719 * @since 1.8
720 */
721 public static long parseUnsignedLong(String s) throws NumberFormatException {
722 return parseUnsignedLong(s, 10);
723 }
724
725 /**
726 * Returns a {@code Long} object holding the value
727 * extracted from the specified {@code String} when parsed
728 * with the radix given by the second argument. The first
729 * argument is interpreted as representing a signed
730 * {@code long} in the radix specified by the second
731 * argument, exactly as if the arguments were given to the {@link
732 * #parseLong(java.lang.String, int)} method. The result is a
733 * {@code Long} object that represents the {@code long}
734 * value specified by the string.
735 *
736 * <p>In other words, this method returns a {@code Long} object equal
737 * to the value of:
738 *
739 * <blockquote>
740 * {@code new Long(Long.parseLong(s, radix))}
741 * </blockquote>
742 *
743 * @param s the string to be parsed
744 * @param radix the radix to be used in interpreting {@code s}
745 * @return a {@code Long} object holding the value
746 * represented by the string argument in the specified
747 * radix.
748 * @throws NumberFormatException If the {@code String} does not
749 * contain a parsable {@code long}.
750 */
751 public static Long valueOf(String s, int radix) throws NumberFormatException {
752 return Long.valueOf(parseLong(s, radix));
753 }
754
755 /**
756 * Returns a {@code Long} object holding the value
757 * of the specified {@code String}. The argument is
758 * interpreted as representing a signed decimal {@code long},
759 * exactly as if the argument were given to the {@link
760 * #parseLong(java.lang.String)} method. The result is a
761 * {@code Long} object that represents the integer value
762 * specified by the string.
763 *
764 * <p>In other words, this method returns a {@code Long} object
765 * equal to the value of:
766 *
767 * <blockquote>
768 * {@code new Long(Long.parseLong(s))}
769 * </blockquote>
770 *
771 * @param s the string to be parsed.
772 * @return a {@code Long} object holding the value
773 * represented by the string argument.
774 * @throws NumberFormatException If the string cannot be parsed
775 * as a {@code long}.
776 */
777 public static Long valueOf(String s) throws NumberFormatException
778 {
779 return Long.valueOf(parseLong(s, 10));
780 }
781
782 private static class LongCache {
783 private LongCache(){}
784
785 static final Long cache[] = new Long[-(-128) + 127 + 1];
786
787 static {
788 for(int i = 0; i < cache.length; i++)
789 cache[i] = new Long(i - 128);
790 }
791 }
792
793 /**
794 * Returns a {@code Long} instance representing the specified
795 * {@code long} value.
796 * If a new {@code Long} instance is not required, this method
797 * should generally be used in preference to the constructor
798 * {@link #Long(long)}, as this method is likely to yield
799 * significantly better space and time performance by caching
800 * frequently requested values.
801 *
802 * Note that unlike the {@linkplain Integer#valueOf(int)
803 * corresponding method} in the {@code Integer} class, this method
804 * is <em>not</em> required to cache values within a particular
805 * range.
806 *
807 * @param l a long value.
808 * @return a {@code Long} instance representing {@code l}.
809 * @since 1.5
810 */
811 public static Long valueOf(long l) {
812 final int offset = 128;
813 if (l >= -128 && l <= 127) { // will cache
814 return LongCache.cache[(int)l + offset];
815 }
816 return new Long(l);
817 }
818
819 /**
820 * Decodes a {@code String} into a {@code Long}.
821 * Accepts decimal, hexadecimal, and octal numbers given by the
822 * following grammar:
823 *
824 * <blockquote>
825 * <dl>
826 * <dt><i>DecodableString:</i>
827 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
828 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
829 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
830 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
831 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
832 * <p>
833 * <dt><i>Sign:</i>
834 * <dd>{@code -}
835 * <dd>{@code +}
836 * </dl>
837 * </blockquote>
838 *
839 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
840 * are as defined in section 3.10.1 of
841 * <cite>The Java™ Language Specification</cite>,
842 * except that underscores are not accepted between digits.
843 *
844 * <p>The sequence of characters following an optional
845 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
846 * "{@code #}", or leading zero) is parsed as by the {@code
847 * Long.parseLong} method with the indicated radix (10, 16, or 8).
848 * This sequence of characters must represent a positive value or
849 * a {@link NumberFormatException} will be thrown. The result is
850 * negated if first character of the specified {@code String} is
851 * the minus sign. No whitespace characters are permitted in the
852 * {@code String}.
853 *
854 * @param nm the {@code String} to decode.
855 * @return a {@code Long} object holding the {@code long}
856 * value represented by {@code nm}
857 * @throws NumberFormatException if the {@code String} does not
858 * contain a parsable {@code long}.
859 * @see java.lang.Long#parseLong(String, int)
860 * @since 1.2
861 */
862 public static Long decode(String nm) throws NumberFormatException {
863 int radix = 10;
864 int index = 0;
865 boolean negative = false;
866 Long result;
867
868 if (nm.length() == 0)
869 throw new NumberFormatException("Zero length string");
870 char firstChar = nm.charAt(0);
871 // Handle sign, if present
872 if (firstChar == '-') {
873 negative = true;
874 index++;
875 } else if (firstChar == '+')
876 index++;
877
878 // Handle radix specifier, if present
879 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
880 index += 2;
881 radix = 16;
882 }
883 else if (nm.startsWith("#", index)) {
884 index ++;
885 radix = 16;
886 }
887 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
888 index ++;
889 radix = 8;
890 }
891
892 if (nm.startsWith("-", index) || nm.startsWith("+", index))
893 throw new NumberFormatException("Sign character in wrong position");
894
895 try {
896 result = Long.valueOf(nm.substring(index), radix);
897 result = negative ? Long.valueOf(-result.longValue()) : result;
898 } catch (NumberFormatException e) {
899 // If number is Long.MIN_VALUE, we'll end up here. The next line
900 // handles this case, and causes any genuine format error to be
901 // rethrown.
902 String constant = negative ? ("-" + nm.substring(index))
903 : nm.substring(index);
904 result = Long.valueOf(constant, radix);
905 }
906 return result;
907 }
908
909 /**
910 * The value of the {@code Long}.
911 *
912 * @serial
913 */
914 private final long value;
915
916 /**
917 * Constructs a newly allocated {@code Long} object that
918 * represents the specified {@code long} argument.
919 *
920 * @param value the value to be represented by the
921 * {@code Long} object.
922 */
923 public Long(long value) {
924 this.value = value;
925 }
926
927 /**
928 * Constructs a newly allocated {@code Long} object that
929 * represents the {@code long} value indicated by the
930 * {@code String} parameter. The string is converted to a
931 * {@code long} value in exactly the manner used by the
932 * {@code parseLong} method for radix 10.
933 *
934 * @param s the {@code String} to be converted to a
935 * {@code Long}.
936 * @throws NumberFormatException if the {@code String} does not
937 * contain a parsable {@code long}.
938 * @see java.lang.Long#parseLong(java.lang.String, int)
939 */
940 public Long(String s) throws NumberFormatException {
941 this.value = parseLong(s, 10);
942 }
943
944 /**
945 * Returns the value of this {@code Long} as a {@code byte} after
946 * a narrowing primitive conversion.
947 * @jls 5.1.3 Narrowing Primitive Conversions
948 */
949 public byte byteValue() {
950 return (byte)value;
951 }
952
953 /**
954 * Returns the value of this {@code Long} as a {@code short} after
955 * a narrowing primitive conversion.
956 * @jls 5.1.3 Narrowing Primitive Conversions
957 */
958 public short shortValue() {
959 return (short)value;
960 }
961
962 /**
963 * Returns the value of this {@code Long} as an {@code int} after
964 * a narrowing primitive conversion.
965 * @jls 5.1.3 Narrowing Primitive Conversions
966 */
967 public int intValue() {
968 return (int)value;
969 }
970
971 /**
972 * Returns the value of this {@code Long} as a
973 * {@code long} value.
974 */
975 public long longValue() {
976 return value;
977 }
978
979 /**
980 * Returns the value of this {@code Long} as a {@code float} after
981 * a widening primitive conversion.
982 * @jls 5.1.2 Widening Primitive Conversions
983 */
984 public float floatValue() {
985 return (float)value;
986 }
987
988 /**
989 * Returns the value of this {@code Long} as a {@code double}
990 * after a widening primitive conversion.
991 * @jls 5.1.2 Widening Primitive Conversions
992 */
993 public double doubleValue() {
994 return (double)value;
995 }
996
997 /**
998 * Returns a {@code String} object representing this
999 * {@code Long}'s value. The value is converted to signed
1000 * decimal representation and returned as a string, exactly as if
1001 * the {@code long} value were given as an argument to the
1002 * {@link java.lang.Long#toString(long)} method.
1003 *
1004 * @return a string representation of the value of this object in
1005 * base 10.
1006 */
1007 public String toString() {
1008 return toString(value);
1009 }
1010
1011 /**
1012 * Returns a hash code for this {@code Long}. The result is
1013 * the exclusive OR of the two halves of the primitive
1014 * {@code long} value held by this {@code Long}
1015 * object. That is, the hashcode is the value of the expression:
1016 *
1017 * <blockquote>
1018 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1019 * </blockquote>
1020 *
1021 * @return a hash code value for this object.
1022 */
1023 public int hashCode() {
1024 return (int)(value ^ (value >>> 32));
1025 }
1026
1027 /**
1028 * Compares this object to the specified object. The result is
1029 * {@code true} if and only if the argument is not
1030 * {@code null} and is a {@code Long} object that
1031 * contains the same {@code long} value as this object.
1032 *
1033 * @param obj the object to compare with.
1034 * @return {@code true} if the objects are the same;
1035 * {@code false} otherwise.
1036 */
1037 public boolean equals(Object obj) {
1038 if (obj instanceof Long) {
1039 return value == ((Long)obj).longValue();
1040 }
1041 return false;
1042 }
1043
1044 /**
1045 * Determines the {@code long} value of the system property
1046 * with the specified name.
1047 *
1048 * <p>The first argument is treated as the name of a system
1049 * property. System properties are accessible through the {@link
1050 * java.lang.System#getProperty(java.lang.String)} method. The
1051 * string value of this property is then interpreted as a {@code
1052 * long} value using the grammar supported by {@link Long#decode decode}
1053 * and a {@code Long} object representing this value is returned.
1054 *
1055 * <p>If there is no property with the specified name, if the
1056 * specified name is empty or {@code null}, or if the property
1057 * does not have the correct numeric format, then {@code null} is
1058 * returned.
1059 *
1060 * <p>In other words, this method returns a {@code Long} object
1061 * equal to the value of:
1062 *
1063 * <blockquote>
1064 * {@code getLong(nm, null)}
1065 * </blockquote>
1066 *
1067 * @param nm property name.
1068 * @return the {@code Long} value of the property.
1069 * @throws SecurityException for the same reasons as
1070 * {@link System#getProperty(String) System.getProperty}
1071 * @see java.lang.System#getProperty(java.lang.String)
1072 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1073 */
1074 public static Long getLong(String nm) {
1075 return getLong(nm, null);
1076 }
1077
1078 /**
1079 * Determines the {@code long} value of the system property
1080 * with the specified name.
1081 *
1082 * <p>The first argument is treated as the name of a system
1083 * property. System properties are accessible through the {@link
1084 * java.lang.System#getProperty(java.lang.String)} method. The
1085 * string value of this property is then interpreted as a {@code
1086 * long} value using the grammar supported by {@link Long#decode decode}
1087 * and a {@code Long} object representing this value is returned.
1088 *
1089 * <p>The second argument is the default value. A {@code Long} object
1090 * that represents the value of the second argument is returned if there
1091 * is no property of the specified name, if the property does not have
1092 * the correct numeric format, or if the specified name is empty or null.
1093 *
1094 * <p>In other words, this method returns a {@code Long} object equal
1095 * to the value of:
1096 *
1097 * <blockquote>
1098 * {@code getLong(nm, new Long(val))}
1099 * </blockquote>
1100 *
1101 * but in practice it may be implemented in a manner such as:
1102 *
1103 * <blockquote><pre>
1104 * Long result = getLong(nm, null);
1105 * return (result == null) ? new Long(val) : result;
1106 * </pre></blockquote>
1107 *
1108 * to avoid the unnecessary allocation of a {@code Long} object when
1109 * the default value is not needed.
1110 *
1111 * @param nm property name.
1112 * @param val default value.
1113 * @return the {@code Long} value of the property.
1114 * @throws SecurityException for the same reasons as
1115 * {@link System#getProperty(String) System.getProperty}
1116 * @see java.lang.System#getProperty(java.lang.String)
1117 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1118 */
1119 public static Long getLong(String nm, long val) {
1120 Long result = Long.getLong(nm, null);
1121 return (result == null) ? Long.valueOf(val) : result;
1122 }
1123
1124 /**
1125 * Returns the {@code long} value of the system property with
1126 * the specified name. The first argument is treated as the name
1127 * of a system property. System properties are accessible through
1128 * the {@link java.lang.System#getProperty(java.lang.String)}
1129 * method. The string value of this property is then interpreted
1130 * as a {@code long} value, as per the
1131 * {@link Long#decode decode} method, and a {@code Long} object
1132 * representing this value is returned; in summary:
1133 *
1134 * <ul>
1135 * <li>If the property value begins with the two ASCII characters
1136 * {@code 0x} or the ASCII character {@code #}, not followed by
1137 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1138 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1139 * with radix 16.
1140 * <li>If the property value begins with the ASCII character
1141 * {@code 0} followed by another character, it is parsed as
1142 * an octal integer exactly as by the method {@link
1143 * #valueOf(java.lang.String, int)} with radix 8.
1144 * <li>Otherwise the property value is parsed as a decimal
1145 * integer exactly as by the method
1146 * {@link #valueOf(java.lang.String, int)} with radix 10.
1147 * </ul>
1148 *
1149 * <p>Note that, in every case, neither {@code L}
1150 * (<code>'\u004C'</code>) nor {@code l}
1151 * (<code>'\u006C'</code>) is permitted to appear at the end
1152 * of the property value as a type indicator, as would be
1153 * permitted in Java programming language source code.
1154 *
1155 * <p>The second argument is the default value. The default value is
1156 * returned if there is no property of the specified name, if the
1157 * property does not have the correct numeric format, or if the
1158 * specified name is empty or {@code null}.
1159 *
1160 * @param nm property name.
1161 * @param val default value.
1162 * @return the {@code Long} value of the property.
1163 * @throws SecurityException for the same reasons as
1164 * {@link System#getProperty(String) System.getProperty}
1165 * @see System#getProperty(java.lang.String)
1166 * @see System#getProperty(java.lang.String, java.lang.String)
1167 */
1168 public static Long getLong(String nm, Long val) {
1169 String v = null;
1170 try {
1171 v = System.getProperty(nm);
1172 } catch (IllegalArgumentException | NullPointerException e) {
1173 }
1174 if (v != null) {
1175 try {
1176 return Long.decode(v);
1177 } catch (NumberFormatException e) {
1178 }
1179 }
1180 return val;
1181 }
1182
1183 /**
1184 * Compares two {@code Long} objects numerically.
1185 *
1186 * @param anotherLong the {@code Long} to be compared.
1187 * @return the value {@code 0} if this {@code Long} is
1188 * equal to the argument {@code Long}; a value less than
1189 * {@code 0} if this {@code Long} is numerically less
1190 * than the argument {@code Long}; and a value greater
1191 * than {@code 0} if this {@code Long} is numerically
1192 * greater than the argument {@code Long} (signed
1193 * comparison).
1194 * @since 1.2
1195 */
1196 public int compareTo(Long anotherLong) {
1197 return compare(this.value, anotherLong.value);
1198 }
1199
1200 /**
1201 * Compares two {@code long} values numerically.
1202 * The value returned is identical to what would be returned by:
1203 * <pre>
1204 * Long.valueOf(x).compareTo(Long.valueOf(y))
1205 * </pre>
1206 *
1207 * @param x the first {@code long} to compare
1208 * @param y the second {@code long} to compare
1209 * @return the value {@code 0} if {@code x == y};
1210 * a value less than {@code 0} if {@code x < y}; and
1211 * a value greater than {@code 0} if {@code x > y}
1212 * @since 1.7
1213 */
1214 public static int compare(long x, long y) {
1215 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1216 }
1217
1218 /**
1219 * Compares two {@code long} values numerically treating the values
1220 * as unsigned.
1221 *
1222 * @param x the first {@code long} to compare
1223 * @param y the second {@code long} to compare
1224 * @return the value {@code 0} if {@code x == y}; a value less
1225 * than {@code 0} if {@code x < y} as unsigned values; and
1226 * a value greater than {@code 0} if {@code x > y} as
1227 * unsigned values
1228 * @since 1.8
1229 */
1230 public static int compareUnsigned(long x, long y) {
1231 return compare(x + MIN_VALUE, y + MIN_VALUE);
1232 }
1233
1234
1235 /**
1236 * Returns the unsigned quotient of dividing the first argument by
1237 * the second where each argument and the result is interpreted as
1238 * an unsigned value.
1239 *
1240 * <p>Note that in two's complement arithmetic, the three other
1241 * basic arithmetic operations of add, subtract, and multiply are
1242 * bit-wise identical if the two operands are regarded as both
1243 * being signed or both being unsigned. Therefore separate {@code
1244 * addUnsigned}, etc. methods are not provided.
1245 *
1246 * @return the unsigned quotient of the first argument divided by
1247 * the second argument
1248 * @param dividend the value to be agnitude
1249 // of dividend and divisor.divided
1250 * @param divisor the value doing the dividing
1251 * @see #remainderUnsigned
1252 * @since 1.8
1253 */
1254 public static long divideUnsigned(long dividend, long divisor) {
1255 if (divisor < 0L) { // signed comparison
1256 // Answer must be 0 or 1 depending on relative magnitude
1257 // of dividend and divisor.
1258 return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;
1259 }
1260
1261 if (dividend > 0) // Both inputs non-negative
1262 return dividend/divisor;
1263 else {
1264 /*
1265 * For simple code, leveraging BigInteger. Longer and faster
1266 * code written directly in terms of operations on longs is
1267 * possible; see "Hacker's Delight" for divide and remainder
1268 * algorithms.
1269 */
1270 return toUnsignedBigInteger(dividend).
1271 divide(toUnsignedBigInteger(divisor)).longValue();
1272 }
1273 }
1274
1275 /**
1276 * Returns the unsigned remainder from dividing the first argument
1277 * by the second where each argument and the result is interpreted
1278 * as an unsigned value.
1279 *
1280 * @return the unsigned remainder of the first argument divided by
1281 * the second argument
1282 * @param dividend the value to be divided
1283 * @param divisor the value doing the dividing
1284 * @see #divideUnsigned
1285 * @since 1.8
1286 */
1287 public static long remainderUnsigned(long dividend, long divisor) {
1288 if (dividend > 0 && divisor > 0) { // signed comparisons
1289 return dividend % divisor;
1290 } else {
1291 if (compareUnsigned(dividend, divisor) < 0) // Avoid explicit check for 0 divisor
1292 return dividend;
1293 else
1294 return toUnsignedBigInteger(dividend).
1295 remainder(toUnsignedBigInteger(divisor)).longValue();
1296 }
1297 }
1298
1299 // Bit Twiddling
1300
1301 /**
1302 * The number of bits used to represent a {@code long} value in two's
1303 * complement binary form.
1304 *
1305 * @since 1.5
1306 */
1307 public static final int SIZE = 64;
1308
1309 /**
1310 * Returns a {@code long} value with at most a single one-bit, in the
1311 * position of the highest-order ("leftmost") one-bit in the specified
1312 * {@code long} value. Returns zero if the specified value has no
1313 * one-bits in its two's complement binary representation, that is, if it
1314 * is equal to zero.
1315 *
1316 * @return a {@code long} value with a single one-bit, in the position
1317 * of the highest-order one-bit in the specified value, or zero if
1318 * the specified value is itself equal to zero.
1319 * @since 1.5
1320 */
1321 public static long highestOneBit(long i) {
1322 // HD, Figure 3-1
1323 i |= (i >> 1);
1324 i |= (i >> 2);
1325 i |= (i >> 4);
1326 i |= (i >> 8);
1327 i |= (i >> 16);
1328 i |= (i >> 32);
1329 return i - (i >>> 1);
1330 }
1331
1332 /**
1333 * Returns a {@code long} value with at most a single one-bit, in the
1334 * position of the lowest-order ("rightmost") one-bit in the specified
1335 * {@code long} value. Returns zero if the specified value has no
1336 * one-bits in its two's complement binary representation, that is, if it
1337 * is equal to zero.
1338 *
1339 * @return a {@code long} value with a single one-bit, in the position
1340 * of the lowest-order one-bit in the specified value, or zero if
1341 * the specified value is itself equal to zero.
1342 * @since 1.5
1343 */
1344 public static long lowestOneBit(long i) {
1345 // HD, Section 2-1
1346 return i & -i;
1347 }
1348
1349 /**
1350 * Returns the number of zero bits preceding the highest-order
1351 * ("leftmost") one-bit in the two's complement binary representation
1352 * of the specified {@code long} value. Returns 64 if the
1353 * specified value has no one-bits in its two's complement representation,
1354 * in other words if it is equal to zero.
1355 *
1356 * <p>Note that this method is closely related to the logarithm base 2.
1357 * For all positive {@code long} values x:
1358 * <ul>
1359 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1360 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1361 * </ul>
1362 *
1363 * @return the number of zero bits preceding the highest-order
1364 * ("leftmost") one-bit in the two's complement binary representation
1365 * of the specified {@code long} value, or 64 if the value
1366 * is equal to zero.
1367 * @since 1.5
1368 */
1369 public static int numberOfLeadingZeros(long i) {
1370 // HD, Figure 5-6
1371 if (i == 0)
1372 return 64;
1373 int n = 1;
1374 int x = (int)(i >>> 32);
1375 if (x == 0) { n += 32; x = (int)i; }
1376 if (x >>> 16 == 0) { n += 16; x <<= 16; }
1377 if (x >>> 24 == 0) { n += 8; x <<= 8; }
1378 if (x >>> 28 == 0) { n += 4; x <<= 4; }
1379 if (x >>> 30 == 0) { n += 2; x <<= 2; }
1380 n -= x >>> 31;
1381 return n;
1382 }
1383
1384 /**
1385 * Returns the number of zero bits following the lowest-order ("rightmost")
1386 * one-bit in the two's complement binary representation of the specified
1387 * {@code long} value. Returns 64 if the specified value has no
1388 * one-bits in its two's complement representation, in other words if it is
1389 * equal to zero.
1390 *
1391 * @return the number of zero bits following the lowest-order ("rightmost")
1392 * one-bit in the two's complement binary representation of the
1393 * specified {@code long} value, or 64 if the value is equal
1394 * to zero.
1395 * @since 1.5
1396 */
1397 public static int numberOfTrailingZeros(long i) {
1398 // HD, Figure 5-14
1399 int x, y;
1400 if (i == 0) return 64;
1401 int n = 63;
1402 y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
1403 y = x <<16; if (y != 0) { n = n -16; x = y; }
1404 y = x << 8; if (y != 0) { n = n - 8; x = y; }
1405 y = x << 4; if (y != 0) { n = n - 4; x = y; }
1406 y = x << 2; if (y != 0) { n = n - 2; x = y; }
1407 return n - ((x << 1) >>> 31);
1408 }
1409
1410 /**
1411 * Returns the number of one-bits in the two's complement binary
1412 * representation of the specified {@code long} value. This function is
1413 * sometimes referred to as the <i>population count</i>.
1414 *
1415 * @return the number of one-bits in the two's complement binary
1416 * representation of the specified {@code long} value.
1417 * @since 1.5
1418 */
1419 public static int bitCount(long i) {
1420 // HD, Figure 5-14
1421 i = i - ((i >>> 1) & 0x5555555555555555L);
1422 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1423 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1424 i = i + (i >>> 8);
1425 i = i + (i >>> 16);
1426 i = i + (i >>> 32);
1427 return (int)i & 0x7f;
1428 }
1429
1430 /**
1431 * Returns the value obtained by rotating the two's complement binary
1432 * representation of the specified {@code long} value left by the
1433 * specified number of bits. (Bits shifted out of the left hand, or
1434 * high-order, side reenter on the right, or low-order.)
1435 *
1436 * <p>Note that left rotation with a negative distance is equivalent to
1437 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1438 * distance)}. Note also that rotation by any multiple of 64 is a
1439 * no-op, so all but the last six bits of the rotation distance can be
1440 * ignored, even if the distance is negative: {@code rotateLeft(val,
1441 * distance) == rotateLeft(val, distance & 0x3F)}.
1442 *
1443 * @return the value obtained by rotating the two's complement binary
1444 * representation of the specified {@code long} value left by the
1445 * specified number of bits.
1446 * @since 1.5
1447 */
1448 public static long rotateLeft(long i, int distance) {
1449 return (i << distance) | (i >>> -distance);
1450 }
1451
1452 /**
1453 * Returns the value obtained by rotating the two's complement binary
1454 * representation of the specified {@code long} value right by the
1455 * specified number of bits. (Bits shifted out of the right hand, or
1456 * low-order, side reenter on the left, or high-order.)
1457 *
1458 * <p>Note that right rotation with a negative distance is equivalent to
1459 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1460 * distance)}. Note also that rotation by any multiple of 64 is a
1461 * no-op, so all but the last six bits of the rotation distance can be
1462 * ignored, even if the distance is negative: {@code rotateRight(val,
1463 * distance) == rotateRight(val, distance & 0x3F)}.
1464 *
1465 * @return the value obtained by rotating the two's complement binary
1466 * representation of the specified {@code long} value right by the
1467 * specified number of bits.
1468 * @since 1.5
1469 */
1470 public static long rotateRight(long i, int distance) {
1471 return (i >>> distance) | (i << -distance);
1472 }
1473
1474 /**
1475 * Returns the value obtained by reversing the order of the bits in the
1476 * two's complement binary representation of the specified {@code long}
1477 * value.
1478 *
1479 * @return the value obtained by reversing order of the bits in the
1480 * specified {@code long} value.
1481 * @since 1.5
1482 */
1483 public static long reverse(long i) {
1484 // HD, Figure 7-1
1485 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1486 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1487 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1488 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1489 i = (i << 48) | ((i & 0xffff0000L) << 16) |
1490 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1491 return i;
1492 }
1493
1494 /**
1495 * Returns the signum function of the specified {@code long} value. (The
1496 * return value is -1 if the specified value is negative; 0 if the
1497 * specified value is zero; and 1 if the specified value is positive.)
1498 *
1499 * @return the signum function of the specified {@code long} value.
1500 * @since 1.5
1501 */
1502 public static int signum(long i) {
1503 // HD, Section 2-7
1504 return (int) ((i >> 63) | (-i >>> 63));
1505 }
1506
1507 /**
1508 * Returns the value obtained by reversing the order of the bytes in the
1509 * two's complement representation of the specified {@code long} value.
1510 *
1511 * @return the value obtained by reversing the bytes in the specified
1512 * {@code long} value.
1513 * @since 1.5
1514 */
1515 public static long reverseBytes(long i) {
1516 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1517 return (i << 48) | ((i & 0xffff0000L) << 16) |
1518 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1519 }
1520
1521 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1522 private static final long serialVersionUID = 4290774380558885855L;
1523 }