1 /*
2 * Copyright (c) 1994, 2013, 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.lang.annotation.Native;
29 import java.math.*;
30
31
32 /**
33 * The {@code Long} class wraps a value of the primitive type {@code
34 * long} in an object. An object of type {@code Long} contains a
35 * single field whose type is {@code long}.
36 *
37 * <p> In addition, this class provides several methods for converting
38 * a {@code long} to a {@code String} and a {@code String} to a {@code
39 * long}, as well as other constants and methods useful when dealing
40 * with a {@code long}.
41 *
42 * <p>Implementation note: The implementations of the "bit twiddling"
43 * methods (such as {@link #highestOneBit(long) highestOneBit} and
44 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
45 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
46 * Delight</i>, (Addison Wesley, 2002).
47 *
48 * @author Lee Boynton
49 * @author Arthur van Hoff
50 * @author Josh Bloch
51 * @author Joseph D. Darcy
52 * @since JDK1.0
53 */
54 public final class Long extends Number implements Comparable<Long> {
55 /**
56 * A constant holding the minimum value a {@code long} can
57 * have, -2<sup>63</sup>.
58 */
59 @Native public static final long MIN_VALUE = 0x8000000000000000L;
60
61 /**
62 * A constant holding the maximum value a {@code long} can
63 * have, 2<sup>63</sup>-1.
64 */
65 @Native public static final long MAX_VALUE = 0x7fffffffffffffffL;
66
67 /**
68 * The {@code Class} instance representing the primitive type
69 * {@code long}.
70 *
71 * @since JDK1.1
72 */
73 @SuppressWarnings("unchecked")
74 public static final Class<Long> TYPE = (Class<Long>) Class.getPrimitiveClass("long");
75
76 /**
77 * Returns a string representation of the first argument in the
78 * radix specified by the second argument.
79 *
80 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
81 * or larger than {@code Character.MAX_RADIX}, then the radix
82 * {@code 10} is used instead.
83 *
84 * <p>If the first argument is negative, the first element of the
85 * result is the ASCII minus sign {@code '-'}
86 * ({@code '\u005Cu002d'}). If the first argument is not
87 * negative, no sign character appears in the result.
88 *
89 * <p>The remaining characters of the result represent the magnitude
90 * of the first argument. If the magnitude is zero, it is
91 * represented by a single zero character {@code '0'}
92 * ({@code '\u005Cu0030'}); otherwise, the first character of
93 * the representation of the magnitude will not be the zero
94 * character. The following ASCII characters are used as digits:
95 *
96 * <blockquote>
97 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
98 * </blockquote>
99 *
100 * These are {@code '\u005Cu0030'} through
101 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
102 * {@code '\u005Cu007a'}. If {@code radix} is
103 * <var>N</var>, then the first <var>N</var> of these characters
104 * are used as radix-<var>N</var> digits in the order shown. Thus,
105 * the digits for hexadecimal (radix 16) are
106 * {@code 0123456789abcdef}. If uppercase letters are
107 * desired, the {@link java.lang.String#toUpperCase()} method may
108 * be called on the result:
109 *
110 * <blockquote>
111 * {@code Long.toString(n, 16).toUpperCase()}
112 * </blockquote>
113 *
114 * @param i a {@code long} to be converted to a string.
115 * @param radix the radix to use in the string representation.
116 * @return a string representation of the argument in the specified radix.
117 * @see java.lang.Character#MAX_RADIX
118 * @see java.lang.Character#MIN_RADIX
119 */
120 public static String toString(long i, int radix) {
121 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
122 radix = 10;
123 if (radix == 10)
124 return toString(i);
125 char[] buf = new char[65];
126 int charPos = 64;
127 boolean negative = (i < 0);
128
129 if (!negative) {
130 i = -i;
131 }
132
133 while (i <= -radix) {
134 buf[charPos--] = Integer.digits[(int)(-(i % radix))];
135 i = i / radix;
136 }
137 buf[charPos] = Integer.digits[(int)(-i)];
138
139 if (negative) {
140 buf[--charPos] = '-';
141 }
142
143 return new String(buf, charPos, (65 - charPos));
144 }
145
146 /**
147 * Returns a string representation of the first argument as an
148 * unsigned integer value in the radix specified by the second
149 * argument.
150 *
151 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
152 * or larger than {@code Character.MAX_RADIX}, then the radix
153 * {@code 10} is used instead.
154 *
155 * <p>Note that since the first argument is treated as an unsigned
156 * value, no leading sign character is printed.
157 *
158 * <p>If the magnitude is zero, it is represented by a single zero
159 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
160 * the first character of the representation of the magnitude will
161 * not be the zero character.
162 *
163 * <p>The behavior of radixes and the characters used as digits
164 * are the same as {@link #toString(long, int) toString}.
165 *
166 * @param i an integer to be converted to an unsigned string.
167 * @param radix the radix to use in the string representation.
168 * @return an unsigned string representation of the argument in the specified radix.
169 * @see #toString(long, int)
170 * @since 1.8
171 */
172 public static String toUnsignedString(long i, int radix) {
173 if (i >= 0)
174 return toString(i, radix);
175 else {
176 switch (radix) {
177 case 2:
178 return toBinaryString(i);
179
180 case 4:
181 return toUnsignedString0(i, 2);
182
183 case 8:
184 return toOctalString(i);
185
186 case 10:
187 /*
188 * We can get the effect of an unsigned division by 10
189 * on a long value by first shifting right, yielding a
190 * positive value, and then dividing by 5. This
191 * allows the last digit and preceding digits to be
192 * isolated more quickly than by an initial conversion
193 * to BigInteger.
194 */
195 long quot = (i >>> 1) / 5;
196 long rem = i - quot * 10;
197 return toString(quot) + rem;
198
199 case 16:
200 return toHexString(i);
201
202 case 32:
203 return toUnsignedString0(i, 5);
204
205 default:
206 return toUnsignedBigInteger(i).toString(radix);
207 }
208 }
209 }
210
211 /**
212 * Return a BigInteger equal to the unsigned value of the
213 * argument.
214 */
215 private static BigInteger toUnsignedBigInteger(long i) {
216 if (i >= 0L)
217 return BigInteger.valueOf(i);
218 else {
219 int upper = (int) (i >>> 32);
220 int lower = (int) i;
221
222 // return (upper << 32) + lower
223 return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
224 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
225 }
226 }
227
228 /**
229 * Returns a string representation of the {@code long}
230 * argument as an unsigned integer in base 16.
231 *
232 * <p>The unsigned {@code long} value is the argument plus
233 * 2<sup>64</sup> if the argument is negative; otherwise, it is
234 * equal to the argument. This value is converted to a string of
235 * ASCII digits in hexadecimal (base 16) with no extra
236 * leading {@code 0}s.
237 *
238 * <p>The value of the argument can be recovered from the returned
239 * string {@code s} by calling {@link
240 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
241 * 16)}.
242 *
243 * <p>If the unsigned magnitude is zero, it is represented by a
244 * single zero character {@code '0'} ({@code '\u005Cu0030'});
245 * otherwise, the first character of the representation of the
246 * unsigned magnitude will not be the zero character. The
247 * following characters are used as hexadecimal digits:
248 *
249 * <blockquote>
250 * {@code 0123456789abcdef}
251 * </blockquote>
252 *
253 * These are the characters {@code '\u005Cu0030'} through
254 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
255 * {@code '\u005Cu0066'}. If uppercase letters are desired,
256 * the {@link java.lang.String#toUpperCase()} method may be called
257 * on the result:
258 *
259 * <blockquote>
260 * {@code Long.toHexString(n).toUpperCase()}
261 * </blockquote>
262 *
263 * @param i a {@code long} to be converted to a string.
264 * @return the string representation of the unsigned {@code long}
265 * value represented by the argument in hexadecimal
266 * (base 16).
267 * @see #parseUnsignedLong(String, int)
268 * @see #toUnsignedString(long, int)
269 * @since JDK 1.0.2
270 */
271 public static String toHexString(long i) {
272 return toUnsignedString0(i, 4);
273 }
274
275 /**
276 * Returns a string representation of the {@code long}
277 * argument as an unsigned integer in base 8.
278 *
279 * <p>The unsigned {@code long} value is the argument plus
280 * 2<sup>64</sup> if the argument is negative; otherwise, it is
281 * equal to the argument. This value is converted to a string of
282 * ASCII digits in octal (base 8) with no extra leading
283 * {@code 0}s.
284 *
285 * <p>The value of the argument can be recovered from the returned
286 * string {@code s} by calling {@link
287 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
288 * 8)}.
289 *
290 * <p>If the unsigned magnitude is zero, it is represented by a
291 * single zero character {@code '0'} ({@code '\u005Cu0030'});
292 * otherwise, the first character of the representation of the
293 * unsigned magnitude will not be the zero character. The
294 * following characters are used as octal digits:
295 *
296 * <blockquote>
297 * {@code 01234567}
298 * </blockquote>
299 *
300 * These are the characters {@code '\u005Cu0030'} through
301 * {@code '\u005Cu0037'}.
302 *
303 * @param i a {@code long} to be converted to a string.
304 * @return the string representation of the unsigned {@code long}
305 * value represented by the argument in octal (base 8).
306 * @see #parseUnsignedLong(String, int)
307 * @see #toUnsignedString(long, int)
308 * @since JDK 1.0.2
309 */
310 public static String toOctalString(long i) {
311 return toUnsignedString0(i, 3);
312 }
313
314 /**
315 * Returns a string representation of the {@code long}
316 * argument as an unsigned integer in base 2.
317 *
318 * <p>The unsigned {@code long} value is the argument plus
319 * 2<sup>64</sup> if the argument is negative; otherwise, it is
320 * equal to the argument. This value is converted to a string of
321 * ASCII digits in binary (base 2) with no extra leading
322 * {@code 0}s.
323 *
324 * <p>The value of the argument can be recovered from the returned
325 * string {@code s} by calling {@link
326 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
327 * 2)}.
328 *
329 * <p>If the unsigned magnitude is zero, it is represented by a
330 * single zero character {@code '0'} ({@code '\u005Cu0030'});
331 * otherwise, the first character of the representation of the
332 * unsigned magnitude will not be the zero character. The
333 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
334 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
335 *
336 * @param i a {@code long} to be converted to a string.
337 * @return the string representation of the unsigned {@code long}
338 * value represented by the argument in binary (base 2).
339 * @see #parseUnsignedLong(String, int)
340 * @see #toUnsignedString(long, int)
341 * @since JDK 1.0.2
342 */
343 public static String toBinaryString(long i) {
344 return toUnsignedString0(i, 1);
345 }
346
347 /**
348 * Format a long (treated as unsigned) into a String.
349 * @param val the value to format
350 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
351 */
352 static String toUnsignedString0(long val, int shift) {
353 // assert shift > 0 && shift <=5 : "Illegal shift value";
354 int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
355 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
356 char[] buf = new char[chars];
357
358 formatUnsignedLong(val, shift, buf, 0, chars);
359 return new String(buf, true);
360 }
361
362 /**
363 * Format a long (treated as unsigned) into a character buffer. If
364 * {@code len} exceeds the formatted ASCII representation of {@code val},
365 * {@code buf} will be padded with leading zeroes.
366 *
367 * @param val the unsigned long to format
368 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
369 * @param buf the character buffer to write to
370 * @param offset the offset in the destination buffer to start at
371 * @param len the number of characters to write
372 */
373 static void formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
374 // assert shift > 0 && shift <=5 : "Illegal shift value";
375 // assert offset >= 0 && offset < buf.length : "illegal offset";
376 // assert len > 0 && (offset + len) <= buf.length : "illegal length";
377 int charPos = offset + len;
378 int radix = 1 << shift;
379 int mask = radix - 1;
380 do {
381 buf[--charPos] = Integer.digits[((int) val) & mask];
382 val >>>= shift;
383 } while (charPos > offset);
384 }
385
386 /**
387 * Returns a {@code String} object representing the specified
388 * {@code long}. The argument is converted to signed decimal
389 * representation and returned as a string, exactly as if the
390 * argument and the radix 10 were given as arguments to the {@link
391 * #toString(long, int)} method.
392 *
393 * @param i a {@code long} to be converted.
394 * @return a string representation of the argument in base 10.
395 */
396 public static String toString(long i) {
397 if (i == Long.MIN_VALUE)
398 return "-9223372036854775808";
399 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
400 char[] buf = new char[size];
401 getChars(i, size, buf);
402 return new String(buf, true);
403 }
404
405 /**
406 * Returns a string representation of the argument as an unsigned
407 * decimal value.
408 *
409 * The argument is converted to unsigned decimal representation
410 * and returned as a string exactly as if the argument and radix
411 * 10 were given as arguments to the {@link #toUnsignedString(long,
412 * int)} method.
413 *
414 * @param i an integer to be converted to an unsigned string.
415 * @return an unsigned string representation of the argument.
416 * @see #toUnsignedString(long, int)
417 * @since 1.8
418 */
419 public static String toUnsignedString(long i) {
420 return toUnsignedString(i, 10);
421 }
422
423 /**
424 * Places characters representing the integer i into the
425 * character array buf. The characters are placed into
426 * the buffer backwards starting with the least significant
427 * digit at the specified index (exclusive), and working
428 * backwards from there.
429 *
430 * Will fail if i == Long.MIN_VALUE
431 */
432 static void getChars(long i, int index, char[] buf) {
433 long q;
434 int r;
435 int charPos = index;
436 char sign = 0;
437
438 if (i < 0) {
439 sign = '-';
440 i = -i;
441 }
442
443 // Get 2 digits/iteration using longs until quotient fits into an int
444 while (i > Integer.MAX_VALUE) {
445 q = i / 100;
446 // really: r = i - (q * 100);
447 r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
448 i = q;
449 buf[--charPos] = Integer.DigitOnes[r];
450 buf[--charPos] = Integer.DigitTens[r];
451 }
452
453 // Get 2 digits/iteration using ints
454 int q2;
455 int i2 = (int)i;
456 while (i2 >= 65536) {
457 q2 = i2 / 100;
458 // really: r = i2 - (q * 100);
459 r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
460 i2 = q2;
461 buf[--charPos] = Integer.DigitOnes[r];
462 buf[--charPos] = Integer.DigitTens[r];
463 }
464
465 // Fall thru to fast mode for smaller numbers
466 // assert(i2 <= 65536, i2);
467 for (;;) {
468 q2 = (i2 * 52429) >>> (16+3);
469 r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
470 buf[--charPos] = Integer.digits[r];
471 i2 = q2;
472 if (i2 == 0) break;
473 }
474 if (sign != 0) {
475 buf[--charPos] = sign;
476 }
477 }
478
479 // Requires positive x
480 static int stringSize(long x) {
481 long p = 10;
482 for (int i=1; i<19; i++) {
483 if (x < p)
484 return i;
485 p = 10*p;
486 }
487 return 19;
488 }
489
490 /**
491 * Parses the string argument as a signed {@code long} in the
492 * radix specified by the second argument. The characters in the
493 * string must all be digits of the specified radix (as determined
494 * by whether {@link java.lang.Character#digit(char, int)} returns
495 * a nonnegative value), except that the first character may be an
496 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
497 * indicate a negative value or an ASCII plus sign {@code '+'}
498 * ({@code '\u005Cu002B'}) to indicate a positive value. The
499 * resulting {@code long} value is returned.
500 *
501 * <p>Note that neither the character {@code L}
502 * ({@code '\u005Cu004C'}) nor {@code l}
503 * ({@code '\u005Cu006C'}) is permitted to appear at the end
504 * of the string as a type indicator, as would be permitted in
505 * Java programming language source code - except that either
506 * {@code L} or {@code l} may appear as a digit for a
507 * radix greater than or equal to 22.
508 *
509 * <p>An exception of type {@code NumberFormatException} is
510 * thrown if any of the following situations occurs:
511 * <ul>
512 *
513 * <li>The first argument is {@code null} or is a string of
514 * length zero.
515 *
516 * <li>The {@code radix} is either smaller than {@link
517 * java.lang.Character#MIN_RADIX} or larger than {@link
518 * java.lang.Character#MAX_RADIX}.
519 *
520 * <li>Any character of the string is not a digit of the specified
521 * radix, except that the first character may be a minus sign
522 * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
523 * '+'} ({@code '\u005Cu002B'}) provided that the string is
524 * longer than length 1.
525 *
526 * <li>The value represented by the string is not a value of type
527 * {@code long}.
528 * </ul>
529 *
530 * <p>Examples:
531 * <blockquote><pre>
532 * parseLong("0", 10) returns 0L
533 * parseLong("473", 10) returns 473L
534 * parseLong("+42", 10) returns 42L
535 * parseLong("-0", 10) returns 0L
536 * parseLong("-FF", 16) returns -255L
537 * parseLong("1100110", 2) returns 102L
538 * parseLong("99", 8) throws a NumberFormatException
539 * parseLong("Hazelnut", 10) throws a NumberFormatException
540 * parseLong("Hazelnut", 36) returns 1356099454469L
541 * </pre></blockquote>
542 *
543 * @param s the {@code String} containing the
544 * {@code long} representation to be parsed.
545 * @param radix the radix to be used while parsing {@code s}.
546 * @return the {@code long} represented by the string argument in
547 * the specified radix.
548 * @throws NumberFormatException if the string does not contain a
549 * parsable {@code long}.
550 */
551 public static long parseLong(String s, int radix)
552 throws NumberFormatException
553 {
554 if (s == null) {
555 throw new NumberFormatException("null");
556 }
557
558 if (radix < Character.MIN_RADIX) {
559 throw new NumberFormatException("radix " + radix +
560 " less than Character.MIN_RADIX");
561 }
562 if (radix > Character.MAX_RADIX) {
563 throw new NumberFormatException("radix " + radix +
564 " greater than Character.MAX_RADIX");
565 }
566
567 long result = 0;
568 boolean negative = false;
569 int i = 0, len = s.length();
570 long limit = -Long.MAX_VALUE;
571 long multmin;
572 int digit;
573
574 if (len > 0) {
575 char firstChar = s.charAt(0);
576 if (firstChar < '0') { // Possible leading "+" or "-"
577 if (firstChar == '-') {
578 negative = true;
579 limit = Long.MIN_VALUE;
580 } else if (firstChar != '+')
581 throw NumberFormatException.forInputString(s);
582
583 if (len == 1) // Cannot have lone "+" or "-"
584 throw NumberFormatException.forInputString(s);
585 i++;
586 }
587 multmin = limit / radix;
588 while (i < len) {
589 // Accumulating negatively avoids surprises near MAX_VALUE
590 digit = Character.digit(s.charAt(i++),radix);
591 if (digit < 0) {
592 throw NumberFormatException.forInputString(s);
593 }
594 if (result < multmin) {
595 throw NumberFormatException.forInputString(s);
596 }
597 result *= radix;
598 if (result < limit + digit) {
599 throw NumberFormatException.forInputString(s);
600 }
601 result -= digit;
602 }
603 } else {
604 throw NumberFormatException.forInputString(s);
605 }
606 return negative ? result : -result;
607 }
608
609 /**
610 * Parses the string argument as a signed decimal {@code long}.
611 * The characters in the string must all be decimal digits, except
612 * that the first character may be an ASCII minus sign {@code '-'}
613 * ({@code \u005Cu002D'}) to indicate a negative value or an
614 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
615 * indicate a positive value. The resulting {@code long} value is
616 * returned, exactly as if the argument and the radix {@code 10}
617 * were given as arguments to the {@link
618 * #parseLong(java.lang.String, int)} method.
619 *
620 * <p>Note that neither the character {@code L}
621 * ({@code '\u005Cu004C'}) nor {@code l}
622 * ({@code '\u005Cu006C'}) is permitted to appear at the end
623 * of the string as a type indicator, as would be permitted in
624 * Java programming language source code.
625 *
626 * @param s a {@code String} containing the {@code long}
627 * representation to be parsed
628 * @return the {@code long} represented by the argument in
629 * decimal.
630 * @throws NumberFormatException if the string does not contain a
631 * parsable {@code long}.
632 */
633 public static long parseLong(String s) throws NumberFormatException {
634 return parseLong(s, 10);
635 }
636
637 /**
638 * Parses the string argument as an unsigned {@code long} in the
639 * radix specified by the second argument. An unsigned integer
640 * maps the values usually associated with negative numbers to
641 * positive numbers larger than {@code MAX_VALUE}.
642 *
643 * The characters in the string must all be digits of the
644 * specified radix (as determined by whether {@link
645 * java.lang.Character#digit(char, int)} returns a nonnegative
646 * value), except that the first character may be an ASCII plus
647 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
648 * integer value is returned.
649 *
650 * <p>An exception of type {@code NumberFormatException} is
651 * thrown if any of the following situations occurs:
652 * <ul>
653 * <li>The first argument is {@code null} or is a string of
654 * length zero.
655 *
656 * <li>The radix is either smaller than
657 * {@link java.lang.Character#MIN_RADIX} or
658 * larger than {@link java.lang.Character#MAX_RADIX}.
659 *
660 * <li>Any character of the string is not a digit of the specified
661 * radix, except that the first character may be a plus sign
662 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
663 * string is longer than length 1.
664 *
665 * <li>The value represented by the string is larger than the
666 * largest unsigned {@code long}, 2<sup>64</sup>-1.
667 *
668 * </ul>
669 *
670 *
671 * @param s the {@code String} containing the unsigned integer
672 * representation to be parsed
673 * @param radix the radix to be used while parsing {@code s}.
674 * @return the unsigned {@code long} represented by the string
675 * argument in the specified radix.
676 * @throws NumberFormatException if the {@code String}
677 * does not contain a parsable {@code long}.
678 * @since 1.8
679 */
680 public static long parseUnsignedLong(String s, int radix)
681 throws NumberFormatException {
682 if (s == null) {
683 throw new NumberFormatException("null");
684 }
685
686 int len = s.length();
687 if (len > 0) {
688 char firstChar = s.charAt(0);
689 if (firstChar == '-') {
690 throw new
691 NumberFormatException(String.format("Illegal leading minus sign " +
692 "on unsigned string %s.", s));
693 } else {
694 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
695 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
696 return parseLong(s, radix);
697 }
698
699 // No need for range checks on len due to testing above.
700 long first = parseLong(s.substring(0, len - 1), radix);
701 int second = Character.digit(s.charAt(len - 1), radix);
702 if (second < 0) {
703 throw new NumberFormatException("Bad digit at end of " + s);
704 }
705 long result = first * radix + second;
706 if (compareUnsigned(result, first) < 0) {
707 /*
708 * The maximum unsigned value, (2^64)-1, takes at
709 * most one more digit to represent than the
710 * maximum signed value, (2^63)-1. Therefore,
711 * parsing (len - 1) digits will be appropriately
712 * in-range of the signed parsing. In other
713 * words, if parsing (len -1) digits overflows
714 * signed parsing, parsing len digits will
715 * certainly overflow unsigned parsing.
716 *
717 * The compareUnsigned check above catches
718 * situations where an unsigned overflow occurs
719 * incorporating the contribution of the final
720 * digit.
721 */
722 throw new NumberFormatException(String.format("String value %s exceeds " +
723 "range of unsigned long.", s));
724 }
725 return result;
726 }
727 } else {
728 throw NumberFormatException.forInputString(s);
729 }
730 }
731
732 /**
733 * Parses the string argument as an unsigned decimal {@code long}. The
734 * characters in the string must all be decimal digits, except
735 * that the first character may be an an ASCII plus sign {@code
736 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
737 * is returned, exactly as if the argument and the radix 10 were
738 * given as arguments to the {@link
739 * #parseUnsignedLong(java.lang.String, int)} method.
740 *
741 * @param s a {@code String} containing the unsigned {@code long}
742 * representation to be parsed
743 * @return the unsigned {@code long} value represented by the decimal string argument
744 * @throws NumberFormatException if the string does not contain a
745 * parsable unsigned integer.
746 * @since 1.8
747 */
748 public static long parseUnsignedLong(String s) throws NumberFormatException {
749 return parseUnsignedLong(s, 10);
750 }
751
752 /**
753 * Returns a {@code Long} object holding the value
754 * extracted from the specified {@code String} when parsed
755 * with the radix given by the second argument. The first
756 * argument is interpreted as representing a signed
757 * {@code long} in the radix specified by the second
758 * argument, exactly as if the arguments were given to the {@link
759 * #parseLong(java.lang.String, int)} method. The result is a
760 * {@code Long} object that represents the {@code long}
761 * value specified by the string.
762 *
763 * <p>In other words, this method returns a {@code Long} object equal
764 * to the value of:
765 *
766 * <blockquote>
767 * {@code new Long(Long.parseLong(s, radix))}
768 * </blockquote>
769 *
770 * @param s the string to be parsed
771 * @param radix the radix to be used in interpreting {@code s}
772 * @return a {@code Long} object holding the value
773 * represented by the string argument in the specified
774 * radix.
775 * @throws NumberFormatException If the {@code String} does not
776 * contain a parsable {@code long}.
777 */
778 public static Long valueOf(String s, int radix) throws NumberFormatException {
779 return Long.valueOf(parseLong(s, radix));
780 }
781
782 /**
783 * Returns a {@code Long} object holding the value
784 * of the specified {@code String}. The argument is
785 * interpreted as representing a signed decimal {@code long},
786 * exactly as if the argument were given to the {@link
787 * #parseLong(java.lang.String)} method. The result is a
788 * {@code Long} object that represents the integer value
789 * specified by the string.
790 *
791 * <p>In other words, this method returns a {@code Long} object
792 * equal to the value of:
793 *
794 * <blockquote>
795 * {@code new Long(Long.parseLong(s))}
796 * </blockquote>
797 *
798 * @param s the string to be parsed.
799 * @return a {@code Long} object holding the value
800 * represented by the string argument.
801 * @throws NumberFormatException If the string cannot be parsed
802 * as a {@code long}.
803 */
804 public static Long valueOf(String s) throws NumberFormatException
805 {
806 return Long.valueOf(parseLong(s, 10));
807 }
808
809 private static class LongCache {
810 private LongCache(){}
811
812 static final Long cache[] = new Long[-(-128) + 127 + 1];
813
814 static {
815 for(int i = 0; i < cache.length; i++)
816 cache[i] = new Long(i - 128);
817 }
818 }
819
820 /**
821 * Returns a {@code Long} instance representing the specified
822 * {@code long} value.
823 * If a new {@code Long} instance is not required, this method
824 * should generally be used in preference to the constructor
825 * {@link #Long(long)}, as this method is likely to yield
826 * significantly better space and time performance by caching
827 * frequently requested values.
828 *
829 * Note that unlike the {@linkplain Integer#valueOf(int)
830 * corresponding method} in the {@code Integer} class, this method
831 * is <em>not</em> required to cache values within a particular
832 * range.
833 *
834 * @param l a long value.
835 * @return a {@code Long} instance representing {@code l}.
836 * @since 1.5
837 */
838 public static Long valueOf(long l) {
839 final int offset = 128;
840 if (l >= -128 && l <= 127) { // will cache
841 return LongCache.cache[(int)l + offset];
842 }
843 return new Long(l);
844 }
845
846 /**
847 * Decodes a {@code String} into a {@code Long}.
848 * Accepts decimal, hexadecimal, and octal numbers given by the
849 * following grammar:
850 *
851 * <blockquote>
852 * <dl>
853 * <dt><i>DecodableString:</i>
854 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
855 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
856 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
857 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
858 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
859 *
860 * <dt><i>Sign:</i>
861 * <dd>{@code -}
862 * <dd>{@code +}
863 * </dl>
864 * </blockquote>
865 *
866 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
867 * are as defined in section 3.10.1 of
868 * <cite>The Java™ Language Specification</cite>,
869 * except that underscores are not accepted between digits.
870 *
871 * <p>The sequence of characters following an optional
872 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
873 * "{@code #}", or leading zero) is parsed as by the {@code
874 * Long.parseLong} method with the indicated radix (10, 16, or 8).
875 * This sequence of characters must represent a positive value or
876 * a {@link NumberFormatException} will be thrown. The result is
877 * negated if first character of the specified {@code String} is
878 * the minus sign. No whitespace characters are permitted in the
879 * {@code String}.
880 *
881 * @param nm the {@code String} to decode.
882 * @return a {@code Long} object holding the {@code long}
883 * value represented by {@code nm}
884 * @throws NumberFormatException if the {@code String} does not
885 * contain a parsable {@code long}.
886 * @see java.lang.Long#parseLong(String, int)
887 * @since 1.2
888 */
889 public static Long decode(String nm) throws NumberFormatException {
890 int radix = 10;
891 int index = 0;
892 boolean negative = false;
893 Long result;
894
895 if (nm.length() == 0)
896 throw new NumberFormatException("Zero length string");
897 char firstChar = nm.charAt(0);
898 // Handle sign, if present
899 if (firstChar == '-') {
900 negative = true;
901 index++;
902 } else if (firstChar == '+')
903 index++;
904
905 // Handle radix specifier, if present
906 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
907 index += 2;
908 radix = 16;
909 }
910 else if (nm.startsWith("#", index)) {
911 index ++;
912 radix = 16;
913 }
914 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
915 index ++;
916 radix = 8;
917 }
918
919 if (nm.startsWith("-", index) || nm.startsWith("+", index))
920 throw new NumberFormatException("Sign character in wrong position");
921
922 try {
923 result = Long.valueOf(nm.substring(index), radix);
924 result = negative ? Long.valueOf(-result.longValue()) : result;
925 } catch (NumberFormatException e) {
926 // If number is Long.MIN_VALUE, we'll end up here. The next line
927 // handles this case, and causes any genuine format error to be
928 // rethrown.
929 String constant = negative ? ("-" + nm.substring(index))
930 : nm.substring(index);
931 result = Long.valueOf(constant, radix);
932 }
933 return result;
934 }
935
936 /**
937 * The value of the {@code Long}.
938 *
939 * @serial
940 */
941 private final long value;
942
943 /**
944 * Constructs a newly allocated {@code Long} object that
945 * represents the specified {@code long} argument.
946 *
947 * @param value the value to be represented by the
948 * {@code Long} object.
949 */
950 public Long(long value) {
951 this.value = value;
952 }
953
954 /**
955 * Constructs a newly allocated {@code Long} object that
956 * represents the {@code long} value indicated by the
957 * {@code String} parameter. The string is converted to a
958 * {@code long} value in exactly the manner used by the
959 * {@code parseLong} method for radix 10.
960 *
961 * @param s the {@code String} to be converted to a
962 * {@code Long}.
963 * @throws NumberFormatException if the {@code String} does not
964 * contain a parsable {@code long}.
965 * @see java.lang.Long#parseLong(java.lang.String, int)
966 */
967 public Long(String s) throws NumberFormatException {
968 this.value = parseLong(s, 10);
969 }
970
971 /**
972 * Returns the value of this {@code Long} as a {@code byte} after
973 * a narrowing primitive conversion.
974 * @jls 5.1.3 Narrowing Primitive Conversions
975 */
976 public byte byteValue() {
977 return (byte)value;
978 }
979
980 /**
981 * Returns the value of this {@code Long} as a {@code short} after
982 * a narrowing primitive conversion.
983 * @jls 5.1.3 Narrowing Primitive Conversions
984 */
985 public short shortValue() {
986 return (short)value;
987 }
988
989 /**
990 * Returns the value of this {@code Long} as an {@code int} after
991 * a narrowing primitive conversion.
992 * @jls 5.1.3 Narrowing Primitive Conversions
993 */
994 public int intValue() {
995 return (int)value;
996 }
997
998 /**
999 * Returns the value of this {@code Long} as a
1000 * {@code long} value.
1001 */
1002 public long longValue() {
1003 return value;
1004 }
1005
1006 /**
1007 * Returns the value of this {@code Long} as a {@code float} after
1008 * a widening primitive conversion.
1009 * @jls 5.1.2 Widening Primitive Conversions
1010 */
1011 public float floatValue() {
1012 return (float)value;
1013 }
1014
1015 /**
1016 * Returns the value of this {@code Long} as a {@code double}
1017 * after a widening primitive conversion.
1018 * @jls 5.1.2 Widening Primitive Conversions
1019 */
1020 public double doubleValue() {
1021 return (double)value;
1022 }
1023
1024 /**
1025 * Returns a {@code String} object representing this
1026 * {@code Long}'s value. The value is converted to signed
1027 * decimal representation and returned as a string, exactly as if
1028 * the {@code long} value were given as an argument to the
1029 * {@link java.lang.Long#toString(long)} method.
1030 *
1031 * @return a string representation of the value of this object in
1032 * base 10.
1033 */
1034 public String toString() {
1035 return toString(value);
1036 }
1037
1038 /**
1039 * Returns a hash code for this {@code Long}. The result is
1040 * the exclusive OR of the two halves of the primitive
1041 * {@code long} value held by this {@code Long}
1042 * object. That is, the hashcode is the value of the expression:
1043 *
1044 * <blockquote>
1045 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1046 * </blockquote>
1047 *
1048 * @return a hash code value for this object.
1049 */
1050 @Override
1051 public int hashCode() {
1052 return Long.hashCode(value);
1053 }
1054
1055 /**
1056 * Returns a hash code for a {@code long} value; compatible with
1057 * {@code Long.hashCode()}.
1058 *
1059 * @param value the value to hash
1060 * @return a hash code value for a {@code long} value.
1061 * @since 1.8
1062 */
1063 public static int hashCode(long value) {
1064 return (int)(value ^ (value >>> 32));
1065 }
1066
1067 /**
1068 * Compares this object to the specified object. The result is
1069 * {@code true} if and only if the argument is not
1070 * {@code null} and is a {@code Long} object that
1071 * contains the same {@code long} value as this object.
1072 *
1073 * @param obj the object to compare with.
1074 * @return {@code true} if the objects are the same;
1075 * {@code false} otherwise.
1076 */
1077 public boolean equals(Object obj) {
1078 if (obj instanceof Long) {
1079 return value == ((Long)obj).longValue();
1080 }
1081 return false;
1082 }
1083
1084 /**
1085 * Determines the {@code long} value of the system property
1086 * with the specified name.
1087 *
1088 * <p>The first argument is treated as the name of a system
1089 * property. System properties are accessible through the {@link
1090 * java.lang.System#getProperty(java.lang.String)} method. The
1091 * string value of this property is then interpreted as a {@code
1092 * long} value using the grammar supported by {@link Long#decode decode}
1093 * and a {@code Long} object representing this value is returned.
1094 *
1095 * <p>If there is no property with the specified name, if the
1096 * specified name is empty or {@code null}, or if the property
1097 * does not have the correct numeric format, then {@code null} is
1098 * returned.
1099 *
1100 * <p>In other words, this method returns a {@code Long} object
1101 * equal to the value of:
1102 *
1103 * <blockquote>
1104 * {@code getLong(nm, null)}
1105 * </blockquote>
1106 *
1107 * @param nm property name.
1108 * @return the {@code Long} value of the property.
1109 * @throws SecurityException for the same reasons as
1110 * {@link System#getProperty(String) System.getProperty}
1111 * @see java.lang.System#getProperty(java.lang.String)
1112 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1113 */
1114 public static Long getLong(String nm) {
1115 return getLong(nm, null);
1116 }
1117
1118 /**
1119 * Determines the {@code long} value of the system property
1120 * with the specified name.
1121 *
1122 * <p>The first argument is treated as the name of a system
1123 * property. System properties are accessible through the {@link
1124 * java.lang.System#getProperty(java.lang.String)} method. The
1125 * string value of this property is then interpreted as a {@code
1126 * long} value using the grammar supported by {@link Long#decode decode}
1127 * and a {@code Long} object representing this value is returned.
1128 *
1129 * <p>The second argument is the default value. A {@code Long} object
1130 * that represents the value of the second argument is returned if there
1131 * is no property of the specified name, if the property does not have
1132 * the correct numeric format, or if the specified name is empty or null.
1133 *
1134 * <p>In other words, this method returns a {@code Long} object equal
1135 * to the value of:
1136 *
1137 * <blockquote>
1138 * {@code getLong(nm, new Long(val))}
1139 * </blockquote>
1140 *
1141 * but in practice it may be implemented in a manner such as:
1142 *
1143 * <blockquote><pre>
1144 * Long result = getLong(nm, null);
1145 * return (result == null) ? new Long(val) : result;
1146 * </pre></blockquote>
1147 *
1148 * to avoid the unnecessary allocation of a {@code Long} object when
1149 * the default value is not needed.
1150 *
1151 * @param nm property name.
1152 * @param val default value.
1153 * @return the {@code Long} value of the property.
1154 * @throws SecurityException for the same reasons as
1155 * {@link System#getProperty(String) System.getProperty}
1156 * @see java.lang.System#getProperty(java.lang.String)
1157 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1158 */
1159 public static Long getLong(String nm, long val) {
1160 Long result = Long.getLong(nm, null);
1161 return (result == null) ? Long.valueOf(val) : result;
1162 }
1163
1164 /**
1165 * Returns the {@code long} value of the system property with
1166 * the specified name. The first argument is treated as the name
1167 * of a system property. System properties are accessible through
1168 * the {@link java.lang.System#getProperty(java.lang.String)}
1169 * method. The string value of this property is then interpreted
1170 * as a {@code long} value, as per the
1171 * {@link Long#decode decode} method, and a {@code Long} object
1172 * representing this value is returned; in summary:
1173 *
1174 * <ul>
1175 * <li>If the property value begins with the two ASCII characters
1176 * {@code 0x} or the ASCII character {@code #}, not followed by
1177 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1178 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1179 * with radix 16.
1180 * <li>If the property value begins with the ASCII character
1181 * {@code 0} followed by another character, it is parsed as
1182 * an octal integer exactly as by the method {@link
1183 * #valueOf(java.lang.String, int)} with radix 8.
1184 * <li>Otherwise the property value is parsed as a decimal
1185 * integer exactly as by the method
1186 * {@link #valueOf(java.lang.String, int)} with radix 10.
1187 * </ul>
1188 *
1189 * <p>Note that, in every case, neither {@code L}
1190 * ({@code '\u005Cu004C'}) nor {@code l}
1191 * ({@code '\u005Cu006C'}) is permitted to appear at the end
1192 * of the property value as a type indicator, as would be
1193 * permitted in Java programming language source code.
1194 *
1195 * <p>The second argument is the default value. The default value is
1196 * returned if there is no property of the specified name, if the
1197 * property does not have the correct numeric format, or if the
1198 * specified name is empty or {@code null}.
1199 *
1200 * @param nm property name.
1201 * @param val default value.
1202 * @return the {@code Long} value of the property.
1203 * @throws SecurityException for the same reasons as
1204 * {@link System#getProperty(String) System.getProperty}
1205 * @see System#getProperty(java.lang.String)
1206 * @see System#getProperty(java.lang.String, java.lang.String)
1207 */
1208 public static Long getLong(String nm, Long val) {
1209 String v = null;
1210 try {
1211 v = System.getProperty(nm);
1212 } catch (IllegalArgumentException | NullPointerException e) {
1213 }
1214 if (v != null) {
1215 try {
1216 return Long.decode(v);
1217 } catch (NumberFormatException e) {
1218 }
1219 }
1220 return val;
1221 }
1222
1223 /**
1224 * Compares two {@code Long} objects numerically.
1225 *
1226 * @param anotherLong the {@code Long} to be compared.
1227 * @return the value {@code 0} if this {@code Long} is
1228 * equal to the argument {@code Long}; a value less than
1229 * {@code 0} if this {@code Long} is numerically less
1230 * than the argument {@code Long}; and a value greater
1231 * than {@code 0} if this {@code Long} is numerically
1232 * greater than the argument {@code Long} (signed
1233 * comparison).
1234 * @since 1.2
1235 */
1236 public int compareTo(Long anotherLong) {
1237 return compare(this.value, anotherLong.value);
1238 }
1239
1240 /**
1241 * Compares two {@code long} values numerically.
1242 * The value returned is identical to what would be returned by:
1243 * <pre>
1244 * Long.valueOf(x).compareTo(Long.valueOf(y))
1245 * </pre>
1246 *
1247 * @param x the first {@code long} to compare
1248 * @param y the second {@code long} to compare
1249 * @return the value {@code 0} if {@code x == y};
1250 * a value less than {@code 0} if {@code x < y}; and
1251 * a value greater than {@code 0} if {@code x > y}
1252 * @since 1.7
1253 */
1254 public static int compare(long x, long y) {
1255 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1256 }
1257
1258 /**
1259 * Compares two {@code long} values numerically treating the values
1260 * as unsigned.
1261 *
1262 * @param x the first {@code long} to compare
1263 * @param y the second {@code long} to compare
1264 * @return the value {@code 0} if {@code x == y}; a value less
1265 * than {@code 0} if {@code x < y} as unsigned values; and
1266 * a value greater than {@code 0} if {@code x > y} as
1267 * unsigned values
1268 * @since 1.8
1269 */
1270 public static int compareUnsigned(long x, long y) {
1271 return compare(x + MIN_VALUE, y + MIN_VALUE);
1272 }
1273
1274
1275 /**
1276 * Returns the unsigned quotient of dividing the first argument by
1277 * the second where each argument and the result is interpreted as
1278 * an unsigned value.
1279 *
1280 * <p>Note that in two's complement arithmetic, the three other
1281 * basic arithmetic operations of add, subtract, and multiply are
1282 * bit-wise identical if the two operands are regarded as both
1283 * being signed or both being unsigned. Therefore separate {@code
1284 * addUnsigned}, etc. methods are not provided.
1285 *
1286 * @param dividend the value to be divided
1287 * @param divisor the value doing the dividing
1288 * @return the unsigned quotient of the first argument divided by
1289 * the second argument
1290 * @see #remainderUnsigned
1291 * @since 1.8
1292 */
1293 public static long divideUnsigned(long dividend, long divisor) {
1294 if (divisor < 0L) { // signed comparison
1295 // Answer must be 0 or 1 depending on relative magnitude
1296 // of dividend and divisor.
1297 return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;
1298 }
1299
1300 if (dividend > 0) // Both inputs non-negative
1301 return dividend/divisor;
1302 else {
1303 /*
1304 * For simple code, leveraging BigInteger. Longer and faster
1305 * code written directly in terms of operations on longs is
1306 * possible; see "Hacker's Delight" for divide and remainder
1307 * algorithms.
1308 */
1309 return toUnsignedBigInteger(dividend).
1310 divide(toUnsignedBigInteger(divisor)).longValue();
1311 }
1312 }
1313
1314 /**
1315 * Returns the unsigned remainder from dividing the first argument
1316 * by the second where each argument and the result is interpreted
1317 * as an unsigned value.
1318 *
1319 * @param dividend the value to be divided
1320 * @param divisor the value doing the dividing
1321 * @return the unsigned remainder of the first argument divided by
1322 * the second argument
1323 * @see #divideUnsigned
1324 * @since 1.8
1325 */
1326 public static long remainderUnsigned(long dividend, long divisor) {
1327 if (dividend > 0 && divisor > 0) { // signed comparisons
1328 return dividend % divisor;
1329 } else {
1330 if (compareUnsigned(dividend, divisor) < 0) // Avoid explicit check for 0 divisor
1331 return dividend;
1332 else
1333 return toUnsignedBigInteger(dividend).
1334 remainder(toUnsignedBigInteger(divisor)).longValue();
1335 }
1336 }
1337
1338 // Bit Twiddling
1339
1340 /**
1341 * The number of bits used to represent a {@code long} value in two's
1342 * complement binary form.
1343 *
1344 * @since 1.5
1345 */
1346 @Native public static final int SIZE = 64;
1347
1348 /**
1349 * The number of bytes used to represent a {@code long} value in two's
1350 * complement binary form.
1351 *
1352 * @since 1.8
1353 */
1354 public static final int BYTES = SIZE / Byte.SIZE;
1355
1356 /**
1357 * Returns a {@code long} value with at most a single one-bit, in the
1358 * position of the highest-order ("leftmost") one-bit in the specified
1359 * {@code long} value. Returns zero if the specified value has no
1360 * one-bits in its two's complement binary representation, that is, if it
1361 * is equal to zero.
1362 *
1363 * @param i the value whose highest one bit is to be computed
1364 * @return a {@code long} value with a single one-bit, in the position
1365 * of the highest-order one-bit in the specified value, or zero if
1366 * the specified value is itself equal to zero.
1367 * @since 1.5
1368 */
1369 public static long highestOneBit(long i) {
1370 // HD, Figure 3-1
1371 i |= (i >> 1);
1372 i |= (i >> 2);
1373 i |= (i >> 4);
1374 i |= (i >> 8);
1375 i |= (i >> 16);
1376 i |= (i >> 32);
1377 return i - (i >>> 1);
1378 }
1379
1380 /**
1381 * Returns a {@code long} value with at most a single one-bit, in the
1382 * position of the lowest-order ("rightmost") one-bit in the specified
1383 * {@code long} value. Returns zero if the specified value has no
1384 * one-bits in its two's complement binary representation, that is, if it
1385 * is equal to zero.
1386 *
1387 * @param i the value whose lowest one bit is to be computed
1388 * @return a {@code long} value with a single one-bit, in the position
1389 * of the lowest-order one-bit in the specified value, or zero if
1390 * the specified value is itself equal to zero.
1391 * @since 1.5
1392 */
1393 public static long lowestOneBit(long i) {
1394 // HD, Section 2-1
1395 return i & -i;
1396 }
1397
1398 /**
1399 * Returns the number of zero bits preceding the highest-order
1400 * ("leftmost") one-bit in the two's complement binary representation
1401 * of the specified {@code long} value. Returns 64 if the
1402 * specified value has no one-bits in its two's complement representation,
1403 * in other words if it is equal to zero.
1404 *
1405 * <p>Note that this method is closely related to the logarithm base 2.
1406 * For all positive {@code long} values x:
1407 * <ul>
1408 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1409 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1410 * </ul>
1411 *
1412 * @param i the value whose number of leading zeros is to be computed
1413 * @return the number of zero bits preceding the highest-order
1414 * ("leftmost") one-bit in the two's complement binary representation
1415 * of the specified {@code long} value, or 64 if the value
1416 * is equal to zero.
1417 * @since 1.5
1418 */
1419 public static int numberOfLeadingZeros(long i) {
1420 // HD, Figure 5-6
1421 if (i == 0)
1422 return 64;
1423 int n = 1;
1424 int x = (int)(i >>> 32);
1425 if (x == 0) { n += 32; x = (int)i; }
1426 if (x >>> 16 == 0) { n += 16; x <<= 16; }
1427 if (x >>> 24 == 0) { n += 8; x <<= 8; }
1428 if (x >>> 28 == 0) { n += 4; x <<= 4; }
1429 if (x >>> 30 == 0) { n += 2; x <<= 2; }
1430 n -= x >>> 31;
1431 return n;
1432 }
1433
1434 /**
1435 * Returns the number of zero bits following the lowest-order ("rightmost")
1436 * one-bit in the two's complement binary representation of the specified
1437 * {@code long} value. Returns 64 if the specified value has no
1438 * one-bits in its two's complement representation, in other words if it is
1439 * equal to zero.
1440 *
1441 * @param i the value whose number of trailing zeros is to be computed
1442 * @return the number of zero bits following the lowest-order ("rightmost")
1443 * one-bit in the two's complement binary representation of the
1444 * specified {@code long} value, or 64 if the value is equal
1445 * to zero.
1446 * @since 1.5
1447 */
1448 public static int numberOfTrailingZeros(long i) {
1449 // HD, Figure 5-14
1450 int x, y;
1451 if (i == 0) return 64;
1452 int n = 63;
1453 y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
1454 y = x <<16; if (y != 0) { n = n -16; x = y; }
1455 y = x << 8; if (y != 0) { n = n - 8; x = y; }
1456 y = x << 4; if (y != 0) { n = n - 4; x = y; }
1457 y = x << 2; if (y != 0) { n = n - 2; x = y; }
1458 return n - ((x << 1) >>> 31);
1459 }
1460
1461 /**
1462 * Returns the number of one-bits in the two's complement binary
1463 * representation of the specified {@code long} value. This function is
1464 * sometimes referred to as the <i>population count</i>.
1465 *
1466 * @param i the value whose bits are to be counted
1467 * @return the number of one-bits in the two's complement binary
1468 * representation of the specified {@code long} value.
1469 * @since 1.5
1470 */
1471 public static int bitCount(long i) {
1472 // HD, Figure 5-14
1473 i = i - ((i >>> 1) & 0x5555555555555555L);
1474 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1475 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1476 i = i + (i >>> 8);
1477 i = i + (i >>> 16);
1478 i = i + (i >>> 32);
1479 return (int)i & 0x7f;
1480 }
1481
1482 /**
1483 * Returns the value obtained by rotating the two's complement binary
1484 * representation of the specified {@code long} value left by the
1485 * specified number of bits. (Bits shifted out of the left hand, or
1486 * high-order, side reenter on the right, or low-order.)
1487 *
1488 * <p>Note that left rotation with a negative distance is equivalent to
1489 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1490 * distance)}. Note also that rotation by any multiple of 64 is a
1491 * no-op, so all but the last six bits of the rotation distance can be
1492 * ignored, even if the distance is negative: {@code rotateLeft(val,
1493 * distance) == rotateLeft(val, distance & 0x3F)}.
1494 *
1495 * @param i the value whose bits are to be rotated left
1496 * @param distance the number of bit positions to rotate left
1497 * @return the value obtained by rotating the two's complement binary
1498 * representation of the specified {@code long} value left by the
1499 * specified number of bits.
1500 * @since 1.5
1501 */
1502 public static long rotateLeft(long i, int distance) {
1503 return (i << distance) | (i >>> -distance);
1504 }
1505
1506 /**
1507 * Returns the value obtained by rotating the two's complement binary
1508 * representation of the specified {@code long} value right by the
1509 * specified number of bits. (Bits shifted out of the right hand, or
1510 * low-order, side reenter on the left, or high-order.)
1511 *
1512 * <p>Note that right rotation with a negative distance is equivalent to
1513 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1514 * distance)}. Note also that rotation by any multiple of 64 is a
1515 * no-op, so all but the last six bits of the rotation distance can be
1516 * ignored, even if the distance is negative: {@code rotateRight(val,
1517 * distance) == rotateRight(val, distance & 0x3F)}.
1518 *
1519 * @param i the value whose bits are to be rotated right
1520 * @param distance the number of bit positions to rotate right
1521 * @return the value obtained by rotating the two's complement binary
1522 * representation of the specified {@code long} value right by the
1523 * specified number of bits.
1524 * @since 1.5
1525 */
1526 public static long rotateRight(long i, int distance) {
1527 return (i >>> distance) | (i << -distance);
1528 }
1529
1530 /**
1531 * Returns the value obtained by reversing the order of the bits in the
1532 * two's complement binary representation of the specified {@code long}
1533 * value.
1534 *
1535 * @param i the value to be reversed
1536 * @return the value obtained by reversing order of the bits in the
1537 * specified {@code long} value.
1538 * @since 1.5
1539 */
1540 public static long reverse(long i) {
1541 // HD, Figure 7-1
1542 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1543 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1544 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1545 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1546 i = (i << 48) | ((i & 0xffff0000L) << 16) |
1547 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1548 return i;
1549 }
1550
1551 /**
1552 * Returns the signum function of the specified {@code long} value. (The
1553 * return value is -1 if the specified value is negative; 0 if the
1554 * specified value is zero; and 1 if the specified value is positive.)
1555 *
1556 * @param i the value whose signum is to be computed
1557 * @return the signum function of the specified {@code long} value.
1558 * @since 1.5
1559 */
1560 public static int signum(long i) {
1561 // HD, Section 2-7
1562 return (int) ((i >> 63) | (-i >>> 63));
1563 }
1564
1565 /**
1566 * Returns the value obtained by reversing the order of the bytes in the
1567 * two's complement representation of the specified {@code long} value.
1568 *
1569 * @param i the value whose bytes are to be reversed
1570 * @return the value obtained by reversing the bytes in the specified
1571 * {@code long} value.
1572 * @since 1.5
1573 */
1574 public static long reverseBytes(long i) {
1575 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1576 return (i << 48) | ((i & 0xffff0000L) << 16) |
1577 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1578 }
1579
1580 /**
1581 * Adds two {@code long} values together as per the + operator.
1582 *
1583 * @param a the first operand
1584 * @param b the second operand
1585 * @return the sum of {@code a} and {@code b}
1586 * @see java.util.function.BinaryOperator
1587 * @since 1.8
1588 */
1589 public static long sum(long a, long b) {
1590 return a + b;
1591 }
1592
1593 /**
1594 * Returns the greater of two {@code long} values
1595 * as if by calling {@link Math#max(long, long) Math.max}.
1596 *
1597 * @param a the first operand
1598 * @param b the second operand
1599 * @return the greater of {@code a} and {@code b}
1600 * @see java.util.function.BinaryOperator
1601 * @since 1.8
1602 */
1603 public static long max(long a, long b) {
1604 return Math.max(a, b);
1605 }
1606
1607 /**
1608 * Returns the smaller of two {@code long} values
1609 * as if by calling {@link Math#min(long, long) Math.min}.
1610 *
1611 * @param a the first operand
1612 * @param b the second operand
1613 * @return the smaller of {@code a} and {@code b}
1614 * @see java.util.function.BinaryOperator
1615 * @since 1.8
1616 */
1617 public static long min(long a, long b) {
1618 return Math.min(a, b);
1619 }
1620
1621 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1622 @Native private static final long serialVersionUID = 4290774380558885855L;
1623 }