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.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 * A constant holding the maximum value a 64-bit unsigned long could
69 * have, 2<sup>64</sup>-1.
70 */
71 private static long MAX_UNSIGNED = 0xffffffffffffffffL;
72
73 /**
74 * The {@code Class} instance representing the primitive type
75 * {@code long}.
76 *
77 * @since JDK1.1
78 */
79 @SuppressWarnings("unchecked")
80 public static final Class<Long> TYPE = (Class<Long>) Class.getPrimitiveClass("long");
81
82 /**
83 * Returns a string representation of the first argument in the
84 * radix specified by the second argument.
85 *
86 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
87 * or larger than {@code Character.MAX_RADIX}, then the radix
88 * {@code 10} is used instead.
89 *
90 * <p>If the first argument is negative, the first element of the
91 * result is the ASCII minus sign {@code '-'}
92 * ({@code '\u005Cu002d'}). If the first argument is not
93 * negative, no sign character appears in the result.
94 *
95 * <p>The remaining characters of the result represent the magnitude
96 * of the first argument. If the magnitude is zero, it is
97 * represented by a single zero character {@code '0'}
98 * ({@code '\u005Cu0030'}); otherwise, the first character of
99 * the representation of the magnitude will not be the zero
100 * character. The following ASCII characters are used as digits:
101 *
102 * <blockquote>
103 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
104 * </blockquote>
105 *
106 * These are {@code '\u005Cu0030'} through
107 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
108 * {@code '\u005Cu007a'}. If {@code radix} is
109 * <var>N</var>, then the first <var>N</var> of these characters
110 * are used as radix-<var>N</var> digits in the order shown. Thus,
111 * the digits for hexadecimal (radix 16) are
112 * {@code 0123456789abcdef}. If uppercase letters are
113 * desired, the {@link java.lang.String#toUpperCase()} method may
114 * be called on the result:
115 *
116 * <blockquote>
117 * {@code Long.toString(n, 16).toUpperCase()}
118 * </blockquote>
119 *
120 * @param i a {@code long} to be converted to a string.
121 * @param radix the radix to use in the string representation.
122 * @return a string representation of the argument in the specified radix.
123 * @see java.lang.Character#MAX_RADIX
124 * @see java.lang.Character#MIN_RADIX
125 */
126 public static String toString(long i, int radix) {
127 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
128 radix = 10;
129 if (radix == 10)
130 return toString(i);
131 char[] buf = new char[65];
132 int charPos = 64;
133 boolean negative = (i < 0);
134
135 if (!negative) {
136 i = -i;
137 }
138
139 while (i <= -radix) {
140 buf[charPos--] = Integer.digits[(int)(-(i % radix))];
141 i = i / radix;
142 }
143 buf[charPos] = Integer.digits[(int)(-i)];
144
145 if (negative) {
146 buf[--charPos] = '-';
147 }
148
149 return new String(buf, charPos, (65 - charPos));
150 }
151
152 /**
153 * Returns a string representation of the first argument as an
154 * unsigned integer value in the radix specified by the second
155 * argument.
156 *
157 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
158 * or larger than {@code Character.MAX_RADIX}, then the radix
159 * {@code 10} is used instead.
160 *
161 * <p>Note that since the first argument is treated as an unsigned
162 * value, no leading sign character is printed.
163 *
164 * <p>If the magnitude is zero, it is represented by a single zero
165 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
166 * the first character of the representation of the magnitude will
167 * not be the zero character.
168 *
169 * <p>The behavior of radixes and the characters used as digits
170 * are the same as {@link #toString(long, int) toString}.
171 *
172 * @param i an integer to be converted to an unsigned string.
173 * @param radix the radix to use in the string representation.
174 * @return an unsigned string representation of the argument in the specified radix.
175 * @see #toString(long, int)
176 * @since 1.8
177 */
178 public static String toUnsignedString(long i, int radix) {
179 if (i >= 0)
180 return toString(i, radix);
181 else {
182 switch (radix) {
183 case 2:
184 return toBinaryString(i);
185
186 case 4:
187 return toUnsignedString0(i, 2);
188
189 case 8:
190 return toOctalString(i);
191
192 case 10:
193 /*
194 * We can get the effect of an unsigned division by 10
195 * on a long value by first shifting right, yielding a
196 * positive value, and then dividing by 5. This
197 * allows the last digit and preceding digits to be
198 * isolated more quickly than by an initial conversion
199 * to BigInteger.
200 */
201 long quot = (i >>> 1) / 5;
202 long rem = i - quot * 10;
203 return toString(quot) + rem;
204
205 case 16:
206 return toHexString(i);
207
208 case 32:
209 return toUnsignedString0(i, 5);
210
211 default:
212 return toUnsignedBigInteger(i).toString(radix);
213 }
214 }
215 }
216
217 /**
218 * Return a BigInteger equal to the unsigned value of the
219 * argument.
220 */
221 private static BigInteger toUnsignedBigInteger(long i) {
222 if (i >= 0L)
223 return BigInteger.valueOf(i);
224 else {
225 int upper = (int) (i >>> 32);
226 int lower = (int) i;
227
228 // return (upper << 32) + lower
229 return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
230 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
231 }
232 }
233
234 /**
235 * Returns a string representation of the {@code long}
236 * argument as an unsigned integer in base 16.
237 *
238 * <p>The unsigned {@code long} value is the argument plus
239 * 2<sup>64</sup> if the argument is negative; otherwise, it is
240 * equal to the argument. This value is converted to a string of
241 * ASCII digits in hexadecimal (base 16) with no extra
242 * leading {@code 0}s.
243 *
244 * <p>The value of the argument can be recovered from the returned
245 * string {@code s} by calling {@link
246 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
247 * 16)}.
248 *
249 * <p>If the unsigned magnitude is zero, it is represented by a
250 * single zero character {@code '0'} ({@code '\u005Cu0030'});
251 * otherwise, the first character of the representation of the
252 * unsigned magnitude will not be the zero character. The
253 * following characters are used as hexadecimal digits:
254 *
255 * <blockquote>
256 * {@code 0123456789abcdef}
257 * </blockquote>
258 *
259 * These are the characters {@code '\u005Cu0030'} through
260 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
261 * {@code '\u005Cu0066'}. If uppercase letters are desired,
262 * the {@link java.lang.String#toUpperCase()} method may be called
263 * on the result:
264 *
265 * <blockquote>
266 * {@code Long.toHexString(n).toUpperCase()}
267 * </blockquote>
268 *
269 * @param i a {@code long} to be converted to a string.
270 * @return the string representation of the unsigned {@code long}
271 * value represented by the argument in hexadecimal
272 * (base 16).
273 * @see #parseUnsignedLong(String, int)
274 * @see #toUnsignedString(long, int)
275 * @since JDK 1.0.2
276 */
277 public static String toHexString(long i) {
278 return toUnsignedString0(i, 4);
279 }
280
281 /**
282 * Returns a string representation of the {@code long}
283 * argument as an unsigned integer in base 8.
284 *
285 * <p>The unsigned {@code long} value is the argument plus
286 * 2<sup>64</sup> if the argument is negative; otherwise, it is
287 * equal to the argument. This value is converted to a string of
288 * ASCII digits in octal (base 8) with no extra leading
289 * {@code 0}s.
290 *
291 * <p>The value of the argument can be recovered from the returned
292 * string {@code s} by calling {@link
293 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
294 * 8)}.
295 *
296 * <p>If the unsigned magnitude is zero, it is represented by a
297 * single zero character {@code '0'} ({@code '\u005Cu0030'});
298 * otherwise, the first character of the representation of the
299 * unsigned magnitude will not be the zero character. The
300 * following characters are used as octal digits:
301 *
302 * <blockquote>
303 * {@code 01234567}
304 * </blockquote>
305 *
306 * These are the characters {@code '\u005Cu0030'} through
307 * {@code '\u005Cu0037'}.
308 *
309 * @param i a {@code long} to be converted to a string.
310 * @return the string representation of the unsigned {@code long}
311 * value represented by the argument in octal (base 8).
312 * @see #parseUnsignedLong(String, int)
313 * @see #toUnsignedString(long, int)
314 * @since JDK 1.0.2
315 */
316 public static String toOctalString(long i) {
317 return toUnsignedString0(i, 3);
318 }
319
320 /**
321 * Returns a string representation of the {@code long}
322 * argument as an unsigned integer in base 2.
323 *
324 * <p>The unsigned {@code long} value is the argument plus
325 * 2<sup>64</sup> if the argument is negative; otherwise, it is
326 * equal to the argument. This value is converted to a string of
327 * ASCII digits in binary (base 2) with no extra leading
328 * {@code 0}s.
329 *
330 * <p>The value of the argument can be recovered from the returned
331 * string {@code s} by calling {@link
332 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
333 * 2)}.
334 *
335 * <p>If the unsigned magnitude is zero, it is represented by a
336 * single zero character {@code '0'} ({@code '\u005Cu0030'});
337 * otherwise, the first character of the representation of the
338 * unsigned magnitude will not be the zero character. The
339 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
340 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
341 *
342 * @param i a {@code long} to be converted to a string.
343 * @return the string representation of the unsigned {@code long}
344 * value represented by the argument in binary (base 2).
345 * @see #parseUnsignedLong(String, int)
346 * @see #toUnsignedString(long, int)
347 * @since JDK 1.0.2
348 */
349 public static String toBinaryString(long i) {
350 return toUnsignedString0(i, 1);
351 }
352
353 /**
354 * Format a long (treated as unsigned) into a String.
355 * @param val the value to format
356 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
357 */
358 static String toUnsignedString0(long val, int shift) {
359 // assert shift > 0 && shift <=5 : "Illegal shift value";
360 int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
361 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
362 char[] buf = new char[chars];
363
364 formatUnsignedLong(val, shift, buf, 0, chars);
365 return new String(buf, true);
366 }
367
368 /**
369 * Format a long (treated as unsigned) into a character buffer.
370 * @param val the unsigned long to format
371 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
372 * @param buf the character buffer to write to
373 * @param offset the offset in the destination buffer to start at
374 * @param len the number of characters to write
375 * @return the lowest character location used
376 */
377 static int formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
378 int charPos = len;
379 int radix = 1 << shift;
380 int mask = radix - 1;
381 do {
382 buf[offset + --charPos] = Integer.digits[((int) val) & mask];
383 val >>>= shift;
384 } while (val != 0 && charPos > 0);
385
386 return charPos;
387 }
388
389 /**
390 * Returns a {@code String} object representing the specified
391 * {@code long}. The argument is converted to signed decimal
392 * representation and returned as a string, exactly as if the
393 * argument and the radix 10 were given as arguments to the {@link
394 * #toString(long, int)} method.
395 *
396 * @param i a {@code long} to be converted.
397 * @return a string representation of the argument in base 10.
398 */
399 public static String toString(long i) {
400 if (i == Long.MIN_VALUE)
401 return "-9223372036854775808";
402 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
403 char[] buf = new char[size];
404 getChars(i, size, buf);
405 return new String(buf, true);
406 }
407
408 /**
409 * Returns a string representation of the argument as an unsigned
410 * decimal value.
411 *
412 * The argument is converted to unsigned decimal representation
413 * and returned as a string exactly as if the argument and radix
414 * 10 were given as arguments to the {@link #toUnsignedString(long,
415 * int)} method.
416 *
417 * @param i an integer to be converted to an unsigned string.
418 * @return an unsigned string representation of the argument.
419 * @see #toUnsignedString(long, int)
420 * @since 1.8
421 */
422 public static String toUnsignedString(long i) {
423 return toUnsignedString(i, 10);
424 }
425
426 /**
427 * Places characters representing the integer i into the
428 * character array buf. The characters are placed into
429 * the buffer backwards starting with the least significant
430 * digit at the specified index (exclusive), and working
431 * backwards from there.
432 *
433 * Will fail if i == Long.MIN_VALUE
434 */
435 static void getChars(long i, int index, char[] buf) {
436 long q;
437 int r;
438 int charPos = index;
439 char sign = 0;
440
441 if (i < 0) {
442 sign = '-';
443 i = -i;
444 }
445
446 // Get 2 digits/iteration using longs until quotient fits into an int
447 while (i > Integer.MAX_VALUE) {
448 q = i / 100;
449 // really: r = i - (q * 100);
450 r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
451 i = q;
452 buf[--charPos] = Integer.DigitOnes[r];
453 buf[--charPos] = Integer.DigitTens[r];
454 }
455
456 // Get 2 digits/iteration using ints
457 int q2;
458 int i2 = (int)i;
459 while (i2 >= 65536) {
460 q2 = i2 / 100;
461 // really: r = i2 - (q * 100);
462 r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
463 i2 = q2;
464 buf[--charPos] = Integer.DigitOnes[r];
465 buf[--charPos] = Integer.DigitTens[r];
466 }
467
468 // Fall thru to fast mode for smaller numbers
469 // assert(i2 <= 65536, i2);
470 for (;;) {
471 q2 = (i2 * 52429) >>> (16+3);
472 r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
473 buf[--charPos] = Integer.digits[r];
474 i2 = q2;
475 if (i2 == 0) break;
476 }
477 if (sign != 0) {
478 buf[--charPos] = sign;
479 }
480 }
481
482 // Requires positive x
483 static int stringSize(long x) {
484 long p = 10;
485 for (int i=1; i<19; i++) {
486 if (x < p)
487 return i;
488 p = 10*p;
489 }
490 return 19;
491 }
492
493 /**
494 * Parses the string argument as a signed {@code long} in the
495 * radix specified by the second argument. The characters in the
496 * string must all be digits of the specified radix (as determined
497 * by whether {@link java.lang.Character#digit(char, int)} returns
498 * a nonnegative value), except that the first character may be an
499 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
500 * indicate a negative value or an ASCII plus sign {@code '+'}
501 * ({@code '\u005Cu002B'}) to indicate a positive value. The
502 * resulting {@code long} value is returned.
503 *
504 * <p>Note that neither the character {@code L}
505 * ({@code '\u005Cu004C'}) nor {@code l}
506 * ({@code '\u005Cu006C'}) is permitted to appear at the end
507 * of the string as a type indicator, as would be permitted in
508 * Java programming language source code - except that either
509 * {@code L} or {@code l} may appear as a digit for a
510 * radix greater than or equal to 22.
511 *
512 * <p>An exception of type {@code NumberFormatException} is
513 * thrown if any of the following situations occurs:
514 * <ul>
515 *
516 * <li>The first argument is {@code null} or is a string of
517 * length zero.
518 *
519 * <li>The {@code radix} is either smaller than {@link
520 * java.lang.Character#MIN_RADIX} or larger than {@link
521 * java.lang.Character#MAX_RADIX}.
522 *
523 * <li>Any character of the string is not a digit of the specified
524 * radix, except that the first character may be a minus sign
525 * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
526 * '+'} ({@code '\u005Cu002B'}) provided that the string is
527 * longer than length 1.
528 *
529 * <li>The value represented by the string is not a value of type
530 * {@code long}.
531 * </ul>
532 *
533 * <p>Examples:
534 * <blockquote><pre>
535 * parseLong("0", 10) returns 0L
536 * parseLong("473", 10) returns 473L
537 * parseLong("+42", 10) returns 42L
538 * parseLong("-0", 10) returns 0L
539 * parseLong("-FF", 16) returns -255L
540 * parseLong("1100110", 2) returns 102L
541 * parseLong("99", 8) throws a NumberFormatException
542 * parseLong("Hazelnut", 10) throws a NumberFormatException
543 * parseLong("Hazelnut", 36) returns 1356099454469L
544 * </pre></blockquote>
545 *
546 * @param s the {@code String} containing the
547 * {@code long} representation to be parsed.
548 * @param radix the radix to be used while parsing {@code s}.
549 * @return the {@code long} represented by the string argument in
550 * the specified radix.
551 * @throws NumberFormatException if the string does not contain a
552 * parsable {@code long}.
553 */
554 public static long parseLong(String s, int radix)
555 throws NumberFormatException
556 {
557 if (s == null) {
558 throw new NumberFormatException("null");
559 }
560
561 if (radix < Character.MIN_RADIX) {
562 throw new NumberFormatException("radix " + radix +
563 " less than Character.MIN_RADIX");
564 }
565 if (radix > Character.MAX_RADIX) {
566 throw new NumberFormatException("radix " + radix +
567 " greater than Character.MAX_RADIX");
568 }
569
570 long result = 0;
571 boolean negative = false;
572 int i = 0, len = s.length();
573 long limit = -Long.MAX_VALUE;
574 long multmin;
575 int digit;
576
577 if (len > 0) {
578 char firstChar = s.charAt(0);
579 if (firstChar < '0') { // Possible leading "+" or "-"
580 if (firstChar == '-') {
581 negative = true;
582 limit = Long.MIN_VALUE;
583 } else if (firstChar != '+')
584 throw NumberFormatException.forInputString(s);
585
586 if (len == 1) // Cannot have lone "+" or "-"
587 throw NumberFormatException.forInputString(s);
588 i++;
589 }
590 multmin = limit / radix;
591 while (i < len) {
592 // Accumulating negatively avoids surprises near MAX_VALUE
593 digit = Character.digit(s.charAt(i++),radix);
594 if (digit < 0) {
595 throw NumberFormatException.forInputString(s);
596 }
597 if (result < multmin) {
598 throw NumberFormatException.forInputString(s);
599 }
600 result *= radix;
601 if (result < limit + digit) {
602 throw NumberFormatException.forInputString(s);
603 }
604 result -= digit;
605 }
606 } else {
607 throw NumberFormatException.forInputString(s);
608 }
609 return negative ? result : -result;
610 }
611
612 /**
613 * Parses the string argument as a signed decimal {@code long}.
614 * The characters in the string must all be decimal digits, except
615 * that the first character may be an ASCII minus sign {@code '-'}
616 * ({@code \u005Cu002D'}) to indicate a negative value or an
617 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
618 * indicate a positive value. The resulting {@code long} value is
619 * returned, exactly as if the argument and the radix {@code 10}
620 * were given as arguments to the {@link
621 * #parseLong(java.lang.String, int)} method.
622 *
623 * <p>Note that neither the character {@code L}
624 * ({@code '\u005Cu004C'}) nor {@code l}
625 * ({@code '\u005Cu006C'}) is permitted to appear at the end
626 * of the string as a type indicator, as would be permitted in
627 * Java programming language source code.
628 *
629 * @param s a {@code String} containing the {@code long}
630 * representation to be parsed
631 * @return the {@code long} represented by the argument in
632 * decimal.
633 * @throws NumberFormatException if the string does not contain a
634 * parsable {@code long}.
635 */
636 public static long parseLong(String s) throws NumberFormatException {
637 return parseLong(s, 10);
638 }
639
640 private static class ParseUnsignedCache {
641 private ParseUnsignedCache(){}
642
643 static final long[] div = new long[Character.MAX_RADIX];
644 static final long[] rem = new long[Character.MAX_RADIX];
645
646 static {
647 // div[0] and rem[0] are unused.
648 for(int radix = 1; radix < Character.MAX_RADIX; radix++) {
649 div[radix] = divideUnsigned(MAX_UNSIGNED, radix);
650 rem[radix] = remainderUnsigned(MAX_UNSIGNED, radix);
651 }
652 }
653 }
654
655 /**
656 * Parses the string argument as an unsigned {@code long} in the
657 * radix specified by the second argument. An unsigned integer
658 * maps the values usually associated with negative numbers to
659 * positive numbers larger than {@code MAX_VALUE}.
660 *
661 * The characters in the string must all be digits of the
662 * specified radix (as determined by whether {@link
663 * java.lang.Character#digit(char, int)} returns a nonnegative
664 * value), except that the first character may be an ASCII plus
665 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
666 * integer value is returned.
667 *
668 * <p>An exception of type {@code NumberFormatException} is
669 * thrown if any of the following situations occurs:
670 * <ul>
671 * <li>The first argument is {@code null} or is a string of
672 * length zero.
673 *
674 * <li>The radix is either smaller than
675 * {@link java.lang.Character#MIN_RADIX} or
676 * larger than {@link java.lang.Character#MAX_RADIX}.
677 *
678 * <li>Any character of the string is not a digit of the specified
679 * radix, except that the first character may be a plus sign
680 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
681 * string is longer than length 1.
682 *
683 * <li>The value represented by the string is larger than the
684 * largest unsigned {@code long}, 2<sup>64</sup>-1.
685 *
686 * </ul>
687 *
688 *
689 * @param s the {@code String} containing the unsigned integer
690 * representation to be parsed
691 * @param radix the radix to be used while parsing {@code s}.
692 * @return the unsigned {@code long} represented by the string
693 * argument in the specified radix.
694 * @throws NumberFormatException if the {@code String}
695 * does not contain a parsable {@code long}.
696 * @since 1.8
697 */
698 public static long parseUnsignedLong(String s, int radix)
699 throws NumberFormatException {
700 if (s == null) {
701 throw new NumberFormatException("null");
702 }
703
704 int len = s.length();
705 if (len > 0) {
706 char firstChar = s.charAt(0);
707 if (firstChar == '-') {
708 throw new
709 NumberFormatException(String.format("Illegal leading minus sign " +
710 "on unsigned string %s.", s));
711 } else {
712 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
713 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
714 return parseLong(s, radix);
715 }
716
717 // No need for range checks on len due to testing above.
718 long first = parseLong(s.substring(0, len - 1), radix);
719 int second = Character.digit(s.charAt(len - 1), radix);
720 if (second < 0) {
721 throw new NumberFormatException("Bad digit at end of " + s);
722 }
723 if (compareUnsigned(first, ParseUnsignedCache.div[radix]) > 0 ||
724 (first == ParseUnsignedCache.div[radix] &&
725 second > ParseUnsignedCache.rem[radix])) {
726 /*
727 * The maximum unsigned value, (2^64)-1, takes at
728 * most one more digit to represent than the
729 * maximum signed value, (2^63)-1. Therefore,
730 * parsing (len - 1) digits will be appropriately
731 * in-range of the signed parsing. In other
732 * words, if parsing (len -1) digits overflows
733 * signed parsing, parsing len digits will
734 * certainly overflow unsigned parsing.
735 *
736 * The compareUnsigned check above catches
737 * situations where an unsigned overflow occurs
738 * incorporating the contribution of the final
739 * digit.
740 */
741 throw new NumberFormatException(String.format("String value %s exceeds " +
742 "range of unsigned long.", s));
743 }
744 return first * radix + second;
745 }
746 } else {
747 throw NumberFormatException.forInputString(s);
748 }
749 }
750
751 /**
752 * Parses the string argument as an unsigned decimal {@code long}. The
753 * characters in the string must all be decimal digits, except
754 * that the first character may be an an ASCII plus sign {@code
755 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
756 * is returned, exactly as if the argument and the radix 10 were
757 * given as arguments to the {@link
758 * #parseUnsignedLong(java.lang.String, int)} method.
759 *
760 * @param s a {@code String} containing the unsigned {@code long}
761 * representation to be parsed
762 * @return the unsigned {@code long} value represented by the decimal string argument
763 * @throws NumberFormatException if the string does not contain a
764 * parsable unsigned integer.
765 * @since 1.8
766 */
767 public static long parseUnsignedLong(String s) throws NumberFormatException {
768 return parseUnsignedLong(s, 10);
769 }
770
771 /**
772 * Returns a {@code Long} object holding the value
773 * extracted from the specified {@code String} when parsed
774 * with the radix given by the second argument. The first
775 * argument is interpreted as representing a signed
776 * {@code long} in the radix specified by the second
777 * argument, exactly as if the arguments were given to the {@link
778 * #parseLong(java.lang.String, int)} method. The result is a
779 * {@code Long} object that represents the {@code long}
780 * value specified by the string.
781 *
782 * <p>In other words, this method returns a {@code Long} object equal
783 * to the value of:
784 *
785 * <blockquote>
786 * {@code new Long(Long.parseLong(s, radix))}
787 * </blockquote>
788 *
789 * @param s the string to be parsed
790 * @param radix the radix to be used in interpreting {@code s}
791 * @return a {@code Long} object holding the value
792 * represented by the string argument in the specified
793 * radix.
794 * @throws NumberFormatException If the {@code String} does not
795 * contain a parsable {@code long}.
796 */
797 public static Long valueOf(String s, int radix) throws NumberFormatException {
798 return Long.valueOf(parseLong(s, radix));
799 }
800
801 /**
802 * Returns a {@code Long} object holding the value
803 * of the specified {@code String}. The argument is
804 * interpreted as representing a signed decimal {@code long},
805 * exactly as if the argument were given to the {@link
806 * #parseLong(java.lang.String)} method. The result is a
807 * {@code Long} object that represents the integer value
808 * specified by the string.
809 *
810 * <p>In other words, this method returns a {@code Long} object
811 * equal to the value of:
812 *
813 * <blockquote>
814 * {@code new Long(Long.parseLong(s))}
815 * </blockquote>
816 *
817 * @param s the string to be parsed.
818 * @return a {@code Long} object holding the value
819 * represented by the string argument.
820 * @throws NumberFormatException If the string cannot be parsed
821 * as a {@code long}.
822 */
823 public static Long valueOf(String s) throws NumberFormatException
824 {
825 return Long.valueOf(parseLong(s, 10));
826 }
827
828 private static class LongCache {
829 private LongCache(){}
830
831 static final Long cache[] = new Long[-(-128) + 127 + 1];
832
833 static {
834 for(int i = 0; i < cache.length; i++)
835 cache[i] = new Long(i - 128);
836 }
837 }
838
839 /**
840 * Returns a {@code Long} instance representing the specified
841 * {@code long} value.
842 * If a new {@code Long} instance is not required, this method
843 * should generally be used in preference to the constructor
844 * {@link #Long(long)}, as this method is likely to yield
845 * significantly better space and time performance by caching
846 * frequently requested values.
847 *
848 * Note that unlike the {@linkplain Integer#valueOf(int)
849 * corresponding method} in the {@code Integer} class, this method
850 * is <em>not</em> required to cache values within a particular
851 * range.
852 *
853 * @param l a long value.
854 * @return a {@code Long} instance representing {@code l}.
855 * @since 1.5
856 */
857 public static Long valueOf(long l) {
858 final int offset = 128;
859 if (l >= -128 && l <= 127) { // will cache
860 return LongCache.cache[(int)l + offset];
861 }
862 return new Long(l);
863 }
864
865 /**
866 * Decodes a {@code String} into a {@code Long}.
867 * Accepts decimal, hexadecimal, and octal numbers given by the
868 * following grammar:
869 *
870 * <blockquote>
871 * <dl>
872 * <dt><i>DecodableString:</i>
873 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
874 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
875 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
876 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
877 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
878 *
879 * <dt><i>Sign:</i>
880 * <dd>{@code -}
881 * <dd>{@code +}
882 * </dl>
883 * </blockquote>
884 *
885 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
886 * are as defined in section 3.10.1 of
887 * <cite>The Java™ Language Specification</cite>,
888 * except that underscores are not accepted between digits.
889 *
890 * <p>The sequence of characters following an optional
891 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
892 * "{@code #}", or leading zero) is parsed as by the {@code
893 * Long.parseLong} method with the indicated radix (10, 16, or 8).
894 * This sequence of characters must represent a positive value or
895 * a {@link NumberFormatException} will be thrown. The result is
896 * negated if first character of the specified {@code String} is
897 * the minus sign. No whitespace characters are permitted in the
898 * {@code String}.
899 *
900 * @param nm the {@code String} to decode.
901 * @return a {@code Long} object holding the {@code long}
902 * value represented by {@code nm}
903 * @throws NumberFormatException if the {@code String} does not
904 * contain a parsable {@code long}.
905 * @see java.lang.Long#parseLong(String, int)
906 * @since 1.2
907 */
908 public static Long decode(String nm) throws NumberFormatException {
909 int radix = 10;
910 int index = 0;
911 boolean negative = false;
912 Long result;
913
914 if (nm.length() == 0)
915 throw new NumberFormatException("Zero length string");
916 char firstChar = nm.charAt(0);
917 // Handle sign, if present
918 if (firstChar == '-') {
919 negative = true;
920 index++;
921 } else if (firstChar == '+')
922 index++;
923
924 // Handle radix specifier, if present
925 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
926 index += 2;
927 radix = 16;
928 }
929 else if (nm.startsWith("#", index)) {
930 index ++;
931 radix = 16;
932 }
933 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
934 index ++;
935 radix = 8;
936 }
937
938 if (nm.startsWith("-", index) || nm.startsWith("+", index))
939 throw new NumberFormatException("Sign character in wrong position");
940
941 try {
942 result = Long.valueOf(nm.substring(index), radix);
943 result = negative ? Long.valueOf(-result.longValue()) : result;
944 } catch (NumberFormatException e) {
945 // If number is Long.MIN_VALUE, we'll end up here. The next line
946 // handles this case, and causes any genuine format error to be
947 // rethrown.
948 String constant = negative ? ("-" + nm.substring(index))
949 : nm.substring(index);
950 result = Long.valueOf(constant, radix);
951 }
952 return result;
953 }
954
955 /**
956 * The value of the {@code Long}.
957 *
958 * @serial
959 */
960 private final long value;
961
962 /**
963 * Constructs a newly allocated {@code Long} object that
964 * represents the specified {@code long} argument.
965 *
966 * @param value the value to be represented by the
967 * {@code Long} object.
968 */
969 public Long(long value) {
970 this.value = value;
971 }
972
973 /**
974 * Constructs a newly allocated {@code Long} object that
975 * represents the {@code long} value indicated by the
976 * {@code String} parameter. The string is converted to a
977 * {@code long} value in exactly the manner used by the
978 * {@code parseLong} method for radix 10.
979 *
980 * @param s the {@code String} to be converted to a
981 * {@code Long}.
982 * @throws NumberFormatException if the {@code String} does not
983 * contain a parsable {@code long}.
984 * @see java.lang.Long#parseLong(java.lang.String, int)
985 */
986 public Long(String s) throws NumberFormatException {
987 this.value = parseLong(s, 10);
988 }
989
990 /**
991 * Returns the value of this {@code Long} as a {@code byte} after
992 * a narrowing primitive conversion.
993 * @jls 5.1.3 Narrowing Primitive Conversions
994 */
995 public byte byteValue() {
996 return (byte)value;
997 }
998
999 /**
1000 * Returns the value of this {@code Long} as a {@code short} after
1001 * a narrowing primitive conversion.
1002 * @jls 5.1.3 Narrowing Primitive Conversions
1003 */
1004 public short shortValue() {
1005 return (short)value;
1006 }
1007
1008 /**
1009 * Returns the value of this {@code Long} as an {@code int} after
1010 * a narrowing primitive conversion.
1011 * @jls 5.1.3 Narrowing Primitive Conversions
1012 */
1013 public int intValue() {
1014 return (int)value;
1015 }
1016
1017 /**
1018 * Returns the value of this {@code Long} as a
1019 * {@code long} value.
1020 */
1021 public long longValue() {
1022 return value;
1023 }
1024
1025 /**
1026 * Returns the value of this {@code Long} as a {@code float} after
1027 * a widening primitive conversion.
1028 * @jls 5.1.2 Widening Primitive Conversions
1029 */
1030 public float floatValue() {
1031 return (float)value;
1032 }
1033
1034 /**
1035 * Returns the value of this {@code Long} as a {@code double}
1036 * after a widening primitive conversion.
1037 * @jls 5.1.2 Widening Primitive Conversions
1038 */
1039 public double doubleValue() {
1040 return (double)value;
1041 }
1042
1043 /**
1044 * Returns a {@code String} object representing this
1045 * {@code Long}'s value. The value is converted to signed
1046 * decimal representation and returned as a string, exactly as if
1047 * the {@code long} value were given as an argument to the
1048 * {@link java.lang.Long#toString(long)} method.
1049 *
1050 * @return a string representation of the value of this object in
1051 * base 10.
1052 */
1053 public String toString() {
1054 return toString(value);
1055 }
1056
1057 /**
1058 * Returns a hash code for this {@code Long}. The result is
1059 * the exclusive OR of the two halves of the primitive
1060 * {@code long} value held by this {@code Long}
1061 * object. That is, the hashcode is the value of the expression:
1062 *
1063 * <blockquote>
1064 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1065 * </blockquote>
1066 *
1067 * @return a hash code value for this object.
1068 */
1069 @Override
1070 public int hashCode() {
1071 return Long.hashCode(value);
1072 }
1073
1074 /**
1075 * Returns a hash code for a {@code long} value; compatible with
1076 * {@code Long.hashCode()}.
1077 *
1078 * @param value the value to hash
1079 * @return a hash code value for a {@code long} value.
1080 * @since 1.8
1081 */
1082 public static int hashCode(long value) {
1083 return (int)(value ^ (value >>> 32));
1084 }
1085
1086 /**
1087 * Compares this object to the specified object. The result is
1088 * {@code true} if and only if the argument is not
1089 * {@code null} and is a {@code Long} object that
1090 * contains the same {@code long} value as this object.
1091 *
1092 * @param obj the object to compare with.
1093 * @return {@code true} if the objects are the same;
1094 * {@code false} otherwise.
1095 */
1096 public boolean equals(Object obj) {
1097 if (obj instanceof Long) {
1098 return value == ((Long)obj).longValue();
1099 }
1100 return false;
1101 }
1102
1103 /**
1104 * Determines the {@code long} value of the system property
1105 * with the specified name.
1106 *
1107 * <p>The first argument is treated as the name of a system
1108 * property. System properties are accessible through the {@link
1109 * java.lang.System#getProperty(java.lang.String)} method. The
1110 * string value of this property is then interpreted as a {@code
1111 * long} value using the grammar supported by {@link Long#decode decode}
1112 * and a {@code Long} object representing this value is returned.
1113 *
1114 * <p>If there is no property with the specified name, if the
1115 * specified name is empty or {@code null}, or if the property
1116 * does not have the correct numeric format, then {@code null} is
1117 * returned.
1118 *
1119 * <p>In other words, this method returns a {@code Long} object
1120 * equal to the value of:
1121 *
1122 * <blockquote>
1123 * {@code getLong(nm, null)}
1124 * </blockquote>
1125 *
1126 * @param nm property name.
1127 * @return the {@code Long} value of the property.
1128 * @throws SecurityException for the same reasons as
1129 * {@link System#getProperty(String) System.getProperty}
1130 * @see java.lang.System#getProperty(java.lang.String)
1131 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1132 */
1133 public static Long getLong(String nm) {
1134 return getLong(nm, null);
1135 }
1136
1137 /**
1138 * Determines the {@code long} value of the system property
1139 * with the specified name.
1140 *
1141 * <p>The first argument is treated as the name of a system
1142 * property. System properties are accessible through the {@link
1143 * java.lang.System#getProperty(java.lang.String)} method. The
1144 * string value of this property is then interpreted as a {@code
1145 * long} value using the grammar supported by {@link Long#decode decode}
1146 * and a {@code Long} object representing this value is returned.
1147 *
1148 * <p>The second argument is the default value. A {@code Long} object
1149 * that represents the value of the second argument is returned if there
1150 * is no property of the specified name, if the property does not have
1151 * the correct numeric format, or if the specified name is empty or null.
1152 *
1153 * <p>In other words, this method returns a {@code Long} object equal
1154 * to the value of:
1155 *
1156 * <blockquote>
1157 * {@code getLong(nm, new Long(val))}
1158 * </blockquote>
1159 *
1160 * but in practice it may be implemented in a manner such as:
1161 *
1162 * <blockquote><pre>
1163 * Long result = getLong(nm, null);
1164 * return (result == null) ? new Long(val) : result;
1165 * </pre></blockquote>
1166 *
1167 * to avoid the unnecessary allocation of a {@code Long} object when
1168 * the default value is not needed.
1169 *
1170 * @param nm property name.
1171 * @param val default value.
1172 * @return the {@code Long} value of the property.
1173 * @throws SecurityException for the same reasons as
1174 * {@link System#getProperty(String) System.getProperty}
1175 * @see java.lang.System#getProperty(java.lang.String)
1176 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1177 */
1178 public static Long getLong(String nm, long val) {
1179 Long result = Long.getLong(nm, null);
1180 return (result == null) ? Long.valueOf(val) : result;
1181 }
1182
1183 /**
1184 * Returns the {@code long} value of the system property with
1185 * the specified name. The first argument is treated as the name
1186 * of a system property. System properties are accessible through
1187 * the {@link java.lang.System#getProperty(java.lang.String)}
1188 * method. The string value of this property is then interpreted
1189 * as a {@code long} value, as per the
1190 * {@link Long#decode decode} method, and a {@code Long} object
1191 * representing this value is returned; in summary:
1192 *
1193 * <ul>
1194 * <li>If the property value begins with the two ASCII characters
1195 * {@code 0x} or the ASCII character {@code #}, not followed by
1196 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1197 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1198 * with radix 16.
1199 * <li>If the property value begins with the ASCII character
1200 * {@code 0} followed by another character, it is parsed as
1201 * an octal integer exactly as by the method {@link
1202 * #valueOf(java.lang.String, int)} with radix 8.
1203 * <li>Otherwise the property value is parsed as a decimal
1204 * integer exactly as by the method
1205 * {@link #valueOf(java.lang.String, int)} with radix 10.
1206 * </ul>
1207 *
1208 * <p>Note that, in every case, neither {@code L}
1209 * ({@code '\u005Cu004C'}) nor {@code l}
1210 * ({@code '\u005Cu006C'}) is permitted to appear at the end
1211 * of the property value as a type indicator, as would be
1212 * permitted in Java programming language source code.
1213 *
1214 * <p>The second argument is the default value. The default value is
1215 * returned if there is no property of the specified name, if the
1216 * property does not have the correct numeric format, or if the
1217 * specified name is empty or {@code null}.
1218 *
1219 * @param nm property name.
1220 * @param val default value.
1221 * @return the {@code Long} value of the property.
1222 * @throws SecurityException for the same reasons as
1223 * {@link System#getProperty(String) System.getProperty}
1224 * @see System#getProperty(java.lang.String)
1225 * @see System#getProperty(java.lang.String, java.lang.String)
1226 */
1227 public static Long getLong(String nm, Long val) {
1228 String v = null;
1229 try {
1230 v = System.getProperty(nm);
1231 } catch (IllegalArgumentException | NullPointerException e) {
1232 }
1233 if (v != null) {
1234 try {
1235 return Long.decode(v);
1236 } catch (NumberFormatException e) {
1237 }
1238 }
1239 return val;
1240 }
1241
1242 /**
1243 * Compares two {@code Long} objects numerically.
1244 *
1245 * @param anotherLong the {@code Long} to be compared.
1246 * @return the value {@code 0} if this {@code Long} is
1247 * equal to the argument {@code Long}; a value less than
1248 * {@code 0} if this {@code Long} is numerically less
1249 * than the argument {@code Long}; and a value greater
1250 * than {@code 0} if this {@code Long} is numerically
1251 * greater than the argument {@code Long} (signed
1252 * comparison).
1253 * @since 1.2
1254 */
1255 public int compareTo(Long anotherLong) {
1256 return compare(this.value, anotherLong.value);
1257 }
1258
1259 /**
1260 * Compares two {@code long} values numerically.
1261 * The value returned is identical to what would be returned by:
1262 * <pre>
1263 * Long.valueOf(x).compareTo(Long.valueOf(y))
1264 * </pre>
1265 *
1266 * @param x the first {@code long} to compare
1267 * @param y the second {@code long} to compare
1268 * @return the value {@code 0} if {@code x == y};
1269 * a value less than {@code 0} if {@code x < y}; and
1270 * a value greater than {@code 0} if {@code x > y}
1271 * @since 1.7
1272 */
1273 public static int compare(long x, long y) {
1274 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1275 }
1276
1277 /**
1278 * Compares two {@code long} values numerically treating the values
1279 * as unsigned.
1280 *
1281 * @param x the first {@code long} to compare
1282 * @param y the second {@code long} to compare
1283 * @return the value {@code 0} if {@code x == y}; a value less
1284 * than {@code 0} if {@code x < y} as unsigned values; and
1285 * a value greater than {@code 0} if {@code x > y} as
1286 * unsigned values
1287 * @since 1.8
1288 */
1289 public static int compareUnsigned(long x, long y) {
1290 return compare(x + MIN_VALUE, y + MIN_VALUE);
1291 }
1292
1293
1294 /**
1295 * Returns the unsigned quotient of dividing the first argument by
1296 * the second where each argument and the result is interpreted as
1297 * an unsigned value.
1298 *
1299 * <p>Note that in two's complement arithmetic, the three other
1300 * basic arithmetic operations of add, subtract, and multiply are
1301 * bit-wise identical if the two operands are regarded as both
1302 * being signed or both being unsigned. Therefore separate {@code
1303 * addUnsigned}, etc. methods are not provided.
1304 *
1305 * @param dividend the value to be divided
1306 * @param divisor the value doing the dividing
1307 * @return the unsigned quotient of the first argument divided by
1308 * the second argument
1309 * @see #remainderUnsigned
1310 * @since 1.8
1311 */
1312 public static long divideUnsigned(long dividend, long divisor) {
1313 if (divisor < 0L) { // signed comparison
1314 // Answer must be 0 or 1 depending on relative magnitude
1315 // of dividend and divisor.
1316 return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;
1317 }
1318
1319 if (dividend > 0) // Both inputs non-negative
1320 return dividend/divisor;
1321 else {
1322 /*
1323 * For simple code, leveraging BigInteger. Longer and faster
1324 * code written directly in terms of operations on longs is
1325 * possible; see "Hacker's Delight" for divide and remainder
1326 * algorithms.
1327 */
1328 return toUnsignedBigInteger(dividend).
1329 divide(toUnsignedBigInteger(divisor)).longValue();
1330 }
1331 }
1332
1333 /**
1334 * Returns the unsigned remainder from dividing the first argument
1335 * by the second where each argument and the result is interpreted
1336 * as an unsigned value.
1337 *
1338 * @param dividend the value to be divided
1339 * @param divisor the value doing the dividing
1340 * @return the unsigned remainder of the first argument divided by
1341 * the second argument
1342 * @see #divideUnsigned
1343 * @since 1.8
1344 */
1345 public static long remainderUnsigned(long dividend, long divisor) {
1346 if (dividend > 0 && divisor > 0) { // signed comparisons
1347 return dividend % divisor;
1348 } else {
1349 if (compareUnsigned(dividend, divisor) < 0) // Avoid explicit check for 0 divisor
1350 return dividend;
1351 else
1352 return toUnsignedBigInteger(dividend).
1353 remainder(toUnsignedBigInteger(divisor)).longValue();
1354 }
1355 }
1356
1357 // Bit Twiddling
1358
1359 /**
1360 * The number of bits used to represent a {@code long} value in two's
1361 * complement binary form.
1362 *
1363 * @since 1.5
1364 */
1365 @Native public static final int SIZE = 64;
1366
1367 /**
1368 * The number of bytes used to represent a {@code long} value in two's
1369 * complement binary form.
1370 *
1371 * @since 1.8
1372 */
1373 public static final int BYTES = SIZE / Byte.SIZE;
1374
1375 /**
1376 * Returns a {@code long} value with at most a single one-bit, in the
1377 * position of the highest-order ("leftmost") one-bit in the specified
1378 * {@code long} value. Returns zero if the specified value has no
1379 * one-bits in its two's complement binary representation, that is, if it
1380 * is equal to zero.
1381 *
1382 * @param i the value whose highest one bit is to be computed
1383 * @return a {@code long} value with a single one-bit, in the position
1384 * of the highest-order one-bit in the specified value, or zero if
1385 * the specified value is itself equal to zero.
1386 * @since 1.5
1387 */
1388 public static long highestOneBit(long i) {
1389 // HD, Figure 3-1
1390 i |= (i >> 1);
1391 i |= (i >> 2);
1392 i |= (i >> 4);
1393 i |= (i >> 8);
1394 i |= (i >> 16);
1395 i |= (i >> 32);
1396 return i - (i >>> 1);
1397 }
1398
1399 /**
1400 * Returns a {@code long} value with at most a single one-bit, in the
1401 * position of the lowest-order ("rightmost") one-bit in the specified
1402 * {@code long} value. Returns zero if the specified value has no
1403 * one-bits in its two's complement binary representation, that is, if it
1404 * is equal to zero.
1405 *
1406 * @param i the value whose lowest one bit is to be computed
1407 * @return a {@code long} value with a single one-bit, in the position
1408 * of the lowest-order one-bit in the specified value, or zero if
1409 * the specified value is itself equal to zero.
1410 * @since 1.5
1411 */
1412 public static long lowestOneBit(long i) {
1413 // HD, Section 2-1
1414 return i & -i;
1415 }
1416
1417 /**
1418 * Returns the number of zero bits preceding the highest-order
1419 * ("leftmost") one-bit in the two's complement binary representation
1420 * of the specified {@code long} value. Returns 64 if the
1421 * specified value has no one-bits in its two's complement representation,
1422 * in other words if it is equal to zero.
1423 *
1424 * <p>Note that this method is closely related to the logarithm base 2.
1425 * For all positive {@code long} values x:
1426 * <ul>
1427 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1428 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1429 * </ul>
1430 *
1431 * @param i the value whose number of leading zeros is to be computed
1432 * @return the number of zero bits preceding the highest-order
1433 * ("leftmost") one-bit in the two's complement binary representation
1434 * of the specified {@code long} value, or 64 if the value
1435 * is equal to zero.
1436 * @since 1.5
1437 */
1438 public static int numberOfLeadingZeros(long i) {
1439 // HD, Figure 5-6
1440 if (i == 0)
1441 return 64;
1442 int n = 1;
1443 int x = (int)(i >>> 32);
1444 if (x == 0) { n += 32; x = (int)i; }
1445 if (x >>> 16 == 0) { n += 16; x <<= 16; }
1446 if (x >>> 24 == 0) { n += 8; x <<= 8; }
1447 if (x >>> 28 == 0) { n += 4; x <<= 4; }
1448 if (x >>> 30 == 0) { n += 2; x <<= 2; }
1449 n -= x >>> 31;
1450 return n;
1451 }
1452
1453 /**
1454 * Returns the number of zero bits following the lowest-order ("rightmost")
1455 * one-bit in the two's complement binary representation of the specified
1456 * {@code long} value. Returns 64 if the specified value has no
1457 * one-bits in its two's complement representation, in other words if it is
1458 * equal to zero.
1459 *
1460 * @param i the value whose number of trailing zeros is to be computed
1461 * @return the number of zero bits following the lowest-order ("rightmost")
1462 * one-bit in the two's complement binary representation of the
1463 * specified {@code long} value, or 64 if the value is equal
1464 * to zero.
1465 * @since 1.5
1466 */
1467 public static int numberOfTrailingZeros(long i) {
1468 // HD, Figure 5-14
1469 int x, y;
1470 if (i == 0) return 64;
1471 int n = 63;
1472 y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
1473 y = x <<16; if (y != 0) { n = n -16; x = y; }
1474 y = x << 8; if (y != 0) { n = n - 8; x = y; }
1475 y = x << 4; if (y != 0) { n = n - 4; x = y; }
1476 y = x << 2; if (y != 0) { n = n - 2; x = y; }
1477 return n - ((x << 1) >>> 31);
1478 }
1479
1480 /**
1481 * Returns the number of one-bits in the two's complement binary
1482 * representation of the specified {@code long} value. This function is
1483 * sometimes referred to as the <i>population count</i>.
1484 *
1485 * @param i the value whose bits are to be counted
1486 * @return the number of one-bits in the two's complement binary
1487 * representation of the specified {@code long} value.
1488 * @since 1.5
1489 */
1490 public static int bitCount(long i) {
1491 // HD, Figure 5-14
1492 i = i - ((i >>> 1) & 0x5555555555555555L);
1493 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1494 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1495 i = i + (i >>> 8);
1496 i = i + (i >>> 16);
1497 i = i + (i >>> 32);
1498 return (int)i & 0x7f;
1499 }
1500
1501 /**
1502 * Returns the value obtained by rotating the two's complement binary
1503 * representation of the specified {@code long} value left by the
1504 * specified number of bits. (Bits shifted out of the left hand, or
1505 * high-order, side reenter on the right, or low-order.)
1506 *
1507 * <p>Note that left rotation with a negative distance is equivalent to
1508 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1509 * distance)}. Note also that rotation by any multiple of 64 is a
1510 * no-op, so all but the last six bits of the rotation distance can be
1511 * ignored, even if the distance is negative: {@code rotateLeft(val,
1512 * distance) == rotateLeft(val, distance & 0x3F)}.
1513 *
1514 * @param i the value whose bits are to be rotated left
1515 * @param distance the number of bit positions to rotate left
1516 * @return the value obtained by rotating the two's complement binary
1517 * representation of the specified {@code long} value left by the
1518 * specified number of bits.
1519 * @since 1.5
1520 */
1521 public static long rotateLeft(long i, int distance) {
1522 return (i << distance) | (i >>> -distance);
1523 }
1524
1525 /**
1526 * Returns the value obtained by rotating the two's complement binary
1527 * representation of the specified {@code long} value right by the
1528 * specified number of bits. (Bits shifted out of the right hand, or
1529 * low-order, side reenter on the left, or high-order.)
1530 *
1531 * <p>Note that right rotation with a negative distance is equivalent to
1532 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1533 * distance)}. Note also that rotation by any multiple of 64 is a
1534 * no-op, so all but the last six bits of the rotation distance can be
1535 * ignored, even if the distance is negative: {@code rotateRight(val,
1536 * distance) == rotateRight(val, distance & 0x3F)}.
1537 *
1538 * @param i the value whose bits are to be rotated right
1539 * @param distance the number of bit positions to rotate right
1540 * @return the value obtained by rotating the two's complement binary
1541 * representation of the specified {@code long} value right by the
1542 * specified number of bits.
1543 * @since 1.5
1544 */
1545 public static long rotateRight(long i, int distance) {
1546 return (i >>> distance) | (i << -distance);
1547 }
1548
1549 /**
1550 * Returns the value obtained by reversing the order of the bits in the
1551 * two's complement binary representation of the specified {@code long}
1552 * value.
1553 *
1554 * @param i the value to be reversed
1555 * @return the value obtained by reversing order of the bits in the
1556 * specified {@code long} value.
1557 * @since 1.5
1558 */
1559 public static long reverse(long i) {
1560 // HD, Figure 7-1
1561 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1562 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1563 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1564 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1565 i = (i << 48) | ((i & 0xffff0000L) << 16) |
1566 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1567 return i;
1568 }
1569
1570 /**
1571 * Returns the signum function of the specified {@code long} value. (The
1572 * return value is -1 if the specified value is negative; 0 if the
1573 * specified value is zero; and 1 if the specified value is positive.)
1574 *
1575 * @param i the value whose signum is to be computed
1576 * @return the signum function of the specified {@code long} value.
1577 * @since 1.5
1578 */
1579 public static int signum(long i) {
1580 // HD, Section 2-7
1581 return (int) ((i >> 63) | (-i >>> 63));
1582 }
1583
1584 /**
1585 * Returns the value obtained by reversing the order of the bytes in the
1586 * two's complement representation of the specified {@code long} value.
1587 *
1588 * @param i the value whose bytes are to be reversed
1589 * @return the value obtained by reversing the bytes in the specified
1590 * {@code long} value.
1591 * @since 1.5
1592 */
1593 public static long reverseBytes(long i) {
1594 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1595 return (i << 48) | ((i & 0xffff0000L) << 16) |
1596 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1597 }
1598
1599 /**
1600 * Adds two {@code long} values together as per the + operator.
1601 *
1602 * @param a the first operand
1603 * @param b the second operand
1604 * @return the sum of {@code a} and {@code b}
1605 * @see java.util.function.BinaryOperator
1606 * @since 1.8
1607 */
1608 public static long sum(long a, long b) {
1609 return a + b;
1610 }
1611
1612 /**
1613 * Returns the greater of two {@code long} values
1614 * as if by calling {@link Math#max(long, long) Math.max}.
1615 *
1616 * @param a the first operand
1617 * @param b the second operand
1618 * @return the greater of {@code a} and {@code b}
1619 * @see java.util.function.BinaryOperator
1620 * @since 1.8
1621 */
1622 public static long max(long a, long b) {
1623 return Math.max(a, b);
1624 }
1625
1626 /**
1627 * Returns the smaller of two {@code long} values
1628 * as if by calling {@link Math#min(long, long) Math.min}.
1629 *
1630 * @param a the first operand
1631 * @param b the second operand
1632 * @return the smaller of {@code a} and {@code b}
1633 * @see java.util.function.BinaryOperator
1634 * @since 1.8
1635 */
1636 public static long min(long a, long b) {
1637 return Math.min(a, b);
1638 }
1639
1640 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1641 @Native private static final long serialVersionUID = 4290774380558885855L;
1642 }