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 * 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.
364 * @param val the unsigned long to format
365 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
366 * @param buf the character buffer to write to
367 * @param offset the offset in the destination buffer to start at
368 * @param len the number of characters to write
369 * @return the lowest character location used
370 */
371 static int formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
372 int charPos = len;
373 int radix = 1 << shift;
374 int mask = radix - 1;
375 do {
376 buf[offset + --charPos] = Integer.digits[((int) val) & mask];
377 val >>>= shift;
378 } while (val != 0 && charPos > 0);
379
380 return charPos;
381 }
382
383 /**
384 * Returns a {@code String} object representing the specified
385 * {@code long}. The argument is converted to signed decimal
386 * representation and returned as a string, exactly as if the
387 * argument and the radix 10 were given as arguments to the {@link
388 * #toString(long, int)} method.
389 *
390 * @param i a {@code long} to be converted.
391 * @return a string representation of the argument in base 10.
392 */
393 public static String toString(long i) {
394 if (i == Long.MIN_VALUE)
395 return "-9223372036854775808";
396 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
397 char[] buf = new char[size];
398 getChars(i, size, buf);
399 return new String(buf, true);
400 }
401
402 /**
403 * Returns a string representation of the argument as an unsigned
404 * decimal value.
405 *
406 * The argument is converted to unsigned decimal representation
407 * and returned as a string exactly as if the argument and radix
408 * 10 were given as arguments to the {@link #toUnsignedString(long,
409 * int)} method.
410 *
411 * @param i an integer to be converted to an unsigned string.
412 * @return an unsigned string representation of the argument.
413 * @see #toUnsignedString(long, int)
414 * @since 1.8
415 */
416 public static String toUnsignedString(long i) {
417 return toUnsignedString(i, 10);
418 }
419
420 /**
421 * Places characters representing the integer i into the
422 * character array buf. The characters are placed into
423 * the buffer backwards starting with the least significant
424 * digit at the specified index (exclusive), and working
425 * backwards from there.
426 *
427 * Will fail if i == Long.MIN_VALUE
428 */
429 static void getChars(long i, int index, char[] buf) {
430 long q;
431 int r;
432 int charPos = index;
433 char sign = 0;
434
435 if (i < 0) {
436 sign = '-';
437 i = -i;
438 }
439
440 // Get 2 digits/iteration using longs until quotient fits into an int
441 while (i > Integer.MAX_VALUE) {
442 q = i / 100;
443 // really: r = i - (q * 100);
444 r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
445 i = q;
446 buf[--charPos] = Integer.DigitOnes[r];
447 buf[--charPos] = Integer.DigitTens[r];
448 }
449
450 // Get 2 digits/iteration using ints
451 int q2;
452 int i2 = (int)i;
453 while (i2 >= 65536) {
454 q2 = i2 / 100;
455 // really: r = i2 - (q * 100);
456 r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
457 i2 = q2;
458 buf[--charPos] = Integer.DigitOnes[r];
459 buf[--charPos] = Integer.DigitTens[r];
460 }
461
462 // Fall thru to fast mode for smaller numbers
463 // assert(i2 <= 65536, i2);
464 for (;;) {
465 q2 = (i2 * 52429) >>> (16+3);
466 r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
467 buf[--charPos] = Integer.digits[r];
468 i2 = q2;
469 if (i2 == 0) break;
470 }
471 if (sign != 0) {
472 buf[--charPos] = sign;
473 }
474 }
475
476 // Requires positive x
477 static int stringSize(long x) {
478 long p = 10;
479 for (int i=1; i<19; i++) {
480 if (x < p)
481 return i;
482 p = 10*p;
483 }
484 return 19;
485 }
486
487 /**
488 * Parses the string argument as a signed {@code long} in the
489 * radix specified by the second argument. The characters in the
490 * string must all be digits of the specified radix (as determined
491 * by whether {@link java.lang.Character#digit(char, int)} returns
492 * a nonnegative value), except that the first character may be an
493 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
494 * indicate a negative value or an ASCII plus sign {@code '+'}
495 * ({@code '\u005Cu002B'}) to indicate a positive value. The
496 * resulting {@code long} value is returned.
497 *
498 * <p>Note that neither the character {@code L}
499 * ({@code '\u005Cu004C'}) nor {@code l}
500 * ({@code '\u005Cu006C'}) is permitted to appear at the end
501 * of the string as a type indicator, as would be permitted in
502 * Java programming language source code - except that either
503 * {@code L} or {@code l} may appear as a digit for a
504 * radix greater than or equal to 22.
505 *
506 * <p>An exception of type {@code NumberFormatException} is
507 * thrown if any of the following situations occurs:
508 * <ul>
509 *
510 * <li>The first argument is {@code null} or is a string of
511 * length zero.
512 *
513 * <li>The {@code radix} is either smaller than {@link
514 * java.lang.Character#MIN_RADIX} or larger than {@link
515 * java.lang.Character#MAX_RADIX}.
516 *
517 * <li>Any character of the string is not a digit of the specified
518 * radix, except that the first character may be a minus sign
519 * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
520 * '+'} ({@code '\u005Cu002B'}) provided that the string is
521 * longer than length 1.
522 *
523 * <li>The value represented by the string is not a value of type
524 * {@code long}.
525 * </ul>
526 *
527 * <p>Examples:
528 * <blockquote><pre>
529 * parseLong("0", 10) returns 0L
530 * parseLong("473", 10) returns 473L
531 * parseLong("+42", 10) returns 42L
532 * parseLong("-0", 10) returns 0L
533 * parseLong("-FF", 16) returns -255L
534 * parseLong("1100110", 2) returns 102L
535 * parseLong("99", 8) throws a NumberFormatException
536 * parseLong("Hazelnut", 10) throws a NumberFormatException
537 * parseLong("Hazelnut", 36) returns 1356099454469L
538 * </pre></blockquote>
539 *
540 * @param s the {@code String} containing the
541 * {@code long} representation to be parsed.
542 * @param radix the radix to be used while parsing {@code s}.
543 * @return the {@code long} represented by the string argument in
544 * the specified radix.
545 * @throws NumberFormatException if the string does not contain a
546 * parsable {@code long}.
547 */
548 public static long parseLong(String s, int radix)
549 throws NumberFormatException
550 {
551 if (s == null) {
552 throw new NumberFormatException("null");
553 }
554
555 if (radix < Character.MIN_RADIX) {
556 throw new NumberFormatException("radix " + radix +
557 " less than Character.MIN_RADIX");
558 }
559 if (radix > Character.MAX_RADIX) {
560 throw new NumberFormatException("radix " + radix +
561 " greater than Character.MAX_RADIX");
562 }
563
564 long result = 0;
565 boolean negative = false;
566 int i = 0, len = s.length();
567 long limit = -Long.MAX_VALUE;
568 long multmin;
569 int digit;
570
571 if (len > 0) {
572 char firstChar = s.charAt(0);
573 if (firstChar < '0') { // Possible leading "+" or "-"
574 if (firstChar == '-') {
575 negative = true;
576 limit = Long.MIN_VALUE;
577 } else if (firstChar != '+')
578 throw NumberFormatException.forInputString(s);
579
580 if (len == 1) // Cannot have lone "+" or "-"
581 throw NumberFormatException.forInputString(s);
582 i++;
583 }
584 multmin = limit / radix;
585 while (i < len) {
586 // Accumulating negatively avoids surprises near MAX_VALUE
587 digit = Character.digit(s.charAt(i++),radix);
588 if (digit < 0) {
589 throw NumberFormatException.forInputString(s);
590 }
591 if (result < multmin) {
592 throw NumberFormatException.forInputString(s);
593 }
594 result *= radix;
595 if (result < limit + digit) {
596 throw NumberFormatException.forInputString(s);
597 }
598 result -= digit;
599 }
600 } else {
601 throw NumberFormatException.forInputString(s);
602 }
603 return negative ? result : -result;
604 }
605
606 /**
607 * Parses the string argument as a signed decimal {@code long}.
608 * The characters in the string must all be decimal digits, except
609 * that the first character may be an ASCII minus sign {@code '-'}
610 * ({@code \u005Cu002D'}) to indicate a negative value or an
611 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
612 * indicate a positive value. The resulting {@code long} value is
613 * returned, exactly as if the argument and the radix {@code 10}
614 * were given as arguments to the {@link
615 * #parseLong(java.lang.String, int)} method.
616 *
617 * <p>Note that neither the character {@code L}
618 * ({@code '\u005Cu004C'}) nor {@code l}
619 * ({@code '\u005Cu006C'}) is permitted to appear at the end
620 * of the string as a type indicator, as would be permitted in
621 * Java programming language source code.
622 *
623 * @param s a {@code String} containing the {@code long}
624 * representation to be parsed
625 * @return the {@code long} represented by the argument in
626 * decimal.
627 * @throws NumberFormatException if the string does not contain a
628 * parsable {@code long}.
629 */
630 public static long parseLong(String s) throws NumberFormatException {
631 return parseLong(s, 10);
632 }
633
634 /**
635 * Parses the string argument as an unsigned {@code long} in the
636 * radix specified by the second argument. An unsigned integer
637 * maps the values usually associated with negative numbers to
638 * positive numbers larger than {@code MAX_VALUE}.
639 *
640 * The characters in the string must all be digits of the
641 * specified radix (as determined by whether {@link
642 * java.lang.Character#digit(char, int)} returns a nonnegative
643 * value), except that the first character may be an ASCII plus
644 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
645 * integer value is returned.
646 *
647 * <p>An exception of type {@code NumberFormatException} is
648 * thrown if any of the following situations occurs:
649 * <ul>
650 * <li>The first argument is {@code null} or is a string of
651 * length zero.
652 *
653 * <li>The radix is either smaller than
654 * {@link java.lang.Character#MIN_RADIX} or
655 * larger than {@link java.lang.Character#MAX_RADIX}.
656 *
657 * <li>Any character of the string is not a digit of the specified
658 * radix, except that the first character may be a plus sign
659 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
660 * string is longer than length 1.
661 *
662 * <li>The value represented by the string is larger than the
663 * largest unsigned {@code long}, 2<sup>64</sup>-1.
664 *
665 * </ul>
666 *
667 *
668 * @param s the {@code String} containing the unsigned integer
669 * representation to be parsed
670 * @param radix the radix to be used while parsing {@code s}.
671 * @return the unsigned {@code long} represented by the string
672 * argument in the specified radix.
673 * @throws NumberFormatException if the {@code String}
674 * does not contain a parsable {@code long}.
675 * @since 1.8
676 */
677 public static long parseUnsignedLong(String s, int radix)
678 throws NumberFormatException {
679 if (s == null) {
680 throw new NumberFormatException("null");
681 }
682
683 int len = s.length();
684 if (len > 0) {
685 char firstChar = s.charAt(0);
686 if (firstChar == '-') {
687 throw new
688 NumberFormatException(String.format("Illegal leading minus sign " +
689 "on unsigned string %s.", s));
690 } else {
691 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
692 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
693 return parseLong(s, radix);
694 }
695
696 // No need for range checks on len due to testing above.
697 long first = parseLong(s.substring(0, len - 1), radix);
698 int second = Character.digit(s.charAt(len - 1), radix);
699 if (second < 0) {
700 throw new NumberFormatException("Bad digit at end of " + s);
701 }
702 long result = first * radix + second;
703 // final int GUARD_BIT = 7;
704 // int guard = radix * (int) (first >>> (64 - GUARD_BIT));
705 int guard = radix * (int) (first >>> 57);
706 // if (guard >= (1 << GUARD_BIT) - Character.MAX_RADIX
707 // && (guard >= (1 << GUARD_BIT) || result >= 0)) {
708 if (guard >= 128 ||
709 (result >= 0 && guard >= 128 - Character.MAX_RADIX)) {
710 /*
711 * The maximum unsigned value, (2^64)-1, takes at
712 * most one more digit to represent than the
713 * maximum signed value, (2^63)-1. Therefore,
714 * parsing (len - 1) digits will be appropriately
715 * in-range of the signed parsing. In other
716 * words, if parsing (len -1) digits overflows
717 * signed parsing, parsing len digits will
718 * certainly overflow unsigned parsing.
719 *
720 * The compareUnsigned check above catches
721 * situations where an unsigned overflow occurs
722 * incorporating the contribution of the final
723 * digit.
724 */
725 throw new NumberFormatException(String.format("String value %s exceeds " +
726 "range of unsigned long.", s));
727 }
728 return result;
729 }
730 } else {
731 throw NumberFormatException.forInputString(s);
732 }
733 }
734
735 /**
736 * Parses the string argument as an unsigned decimal {@code long}. The
737 * characters in the string must all be decimal digits, except
738 * that the first character may be an an ASCII plus sign {@code
739 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
740 * is returned, exactly as if the argument and the radix 10 were
741 * given as arguments to the {@link
742 * #parseUnsignedLong(java.lang.String, int)} method.
743 *
744 * @param s a {@code String} containing the unsigned {@code long}
745 * representation to be parsed
746 * @return the unsigned {@code long} value represented by the decimal string argument
747 * @throws NumberFormatException if the string does not contain a
748 * parsable unsigned integer.
749 * @since 1.8
750 */
751 public static long parseUnsignedLong(String s) throws NumberFormatException {
752 return parseUnsignedLong(s, 10);
753 }
754
755 /**
756 * Returns a {@code Long} object holding the value
757 * extracted from the specified {@code String} when parsed
758 * with the radix given by the second argument. The first
759 * argument is interpreted as representing a signed
760 * {@code long} in the radix specified by the second
761 * argument, exactly as if the arguments were given to the {@link
762 * #parseLong(java.lang.String, int)} method. The result is a
763 * {@code Long} object that represents the {@code long}
764 * value specified by the string.
765 *
766 * <p>In other words, this method returns a {@code Long} object equal
767 * to the value of:
768 *
769 * <blockquote>
770 * {@code new Long(Long.parseLong(s, radix))}
771 * </blockquote>
772 *
773 * @param s the string to be parsed
774 * @param radix the radix to be used in interpreting {@code s}
775 * @return a {@code Long} object holding the value
776 * represented by the string argument in the specified
777 * radix.
778 * @throws NumberFormatException If the {@code String} does not
779 * contain a parsable {@code long}.
780 */
781 public static Long valueOf(String s, int radix) throws NumberFormatException {
782 return Long.valueOf(parseLong(s, radix));
783 }
784
785 /**
786 * Returns a {@code Long} object holding the value
787 * of the specified {@code String}. The argument is
788 * interpreted as representing a signed decimal {@code long},
789 * exactly as if the argument were given to the {@link
790 * #parseLong(java.lang.String)} method. The result is a
791 * {@code Long} object that represents the integer value
792 * specified by the string.
793 *
794 * <p>In other words, this method returns a {@code Long} object
795 * equal to the value of:
796 *
797 * <blockquote>
798 * {@code new Long(Long.parseLong(s))}
799 * </blockquote>
800 *
801 * @param s the string to be parsed.
802 * @return a {@code Long} object holding the value
803 * represented by the string argument.
804 * @throws NumberFormatException If the string cannot be parsed
805 * as a {@code long}.
806 */
807 public static Long valueOf(String s) throws NumberFormatException
808 {
809 return Long.valueOf(parseLong(s, 10));
810 }
811
812 private static class LongCache {
813 private LongCache(){}
814
815 static final Long cache[] = new Long[-(-128) + 127 + 1];
816
817 static {
818 for(int i = 0; i < cache.length; i++)
819 cache[i] = new Long(i - 128);
820 }
821 }
822
823 /**
824 * Returns a {@code Long} instance representing the specified
825 * {@code long} value.
826 * If a new {@code Long} instance is not required, this method
827 * should generally be used in preference to the constructor
828 * {@link #Long(long)}, as this method is likely to yield
829 * significantly better space and time performance by caching
830 * frequently requested values.
831 *
832 * Note that unlike the {@linkplain Integer#valueOf(int)
833 * corresponding method} in the {@code Integer} class, this method
834 * is <em>not</em> required to cache values within a particular
835 * range.
836 *
837 * @param l a long value.
838 * @return a {@code Long} instance representing {@code l}.
839 * @since 1.5
840 */
841 public static Long valueOf(long l) {
842 final int offset = 128;
843 if (l >= -128 && l <= 127) { // will cache
844 return LongCache.cache[(int)l + offset];
845 }
846 return new Long(l);
847 }
848
849 /**
850 * Decodes a {@code String} into a {@code Long}.
851 * Accepts decimal, hexadecimal, and octal numbers given by the
852 * following grammar:
853 *
854 * <blockquote>
855 * <dl>
856 * <dt><i>DecodableString:</i>
857 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
858 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
859 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
860 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
861 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
862 *
863 * <dt><i>Sign:</i>
864 * <dd>{@code -}
865 * <dd>{@code +}
866 * </dl>
867 * </blockquote>
868 *
869 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
870 * are as defined in section 3.10.1 of
871 * <cite>The Java™ Language Specification</cite>,
872 * except that underscores are not accepted between digits.
873 *
874 * <p>The sequence of characters following an optional
875 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
876 * "{@code #}", or leading zero) is parsed as by the {@code
877 * Long.parseLong} method with the indicated radix (10, 16, or 8).
878 * This sequence of characters must represent a positive value or
879 * a {@link NumberFormatException} will be thrown. The result is
880 * negated if first character of the specified {@code String} is
881 * the minus sign. No whitespace characters are permitted in the
882 * {@code String}.
883 *
884 * @param nm the {@code String} to decode.
885 * @return a {@code Long} object holding the {@code long}
886 * value represented by {@code nm}
887 * @throws NumberFormatException if the {@code String} does not
888 * contain a parsable {@code long}.
889 * @see java.lang.Long#parseLong(String, int)
890 * @since 1.2
891 */
892 public static Long decode(String nm) throws NumberFormatException {
893 int radix = 10;
894 int index = 0;
895 boolean negative = false;
896 Long result;
897
898 if (nm.length() == 0)
899 throw new NumberFormatException("Zero length string");
900 char firstChar = nm.charAt(0);
901 // Handle sign, if present
902 if (firstChar == '-') {
903 negative = true;
904 index++;
905 } else if (firstChar == '+')
906 index++;
907
908 // Handle radix specifier, if present
909 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
910 index += 2;
911 radix = 16;
912 }
913 else if (nm.startsWith("#", index)) {
914 index ++;
915 radix = 16;
916 }
917 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
918 index ++;
919 radix = 8;
920 }
921
922 if (nm.startsWith("-", index) || nm.startsWith("+", index))
923 throw new NumberFormatException("Sign character in wrong position");
924
925 try {
926 result = Long.valueOf(nm.substring(index), radix);
927 result = negative ? Long.valueOf(-result.longValue()) : result;
928 } catch (NumberFormatException e) {
929 // If number is Long.MIN_VALUE, we'll end up here. The next line
930 // handles this case, and causes any genuine format error to be
931 // rethrown.
932 String constant = negative ? ("-" + nm.substring(index))
933 : nm.substring(index);
934 result = Long.valueOf(constant, radix);
935 }
936 return result;
937 }
938
939 /**
940 * The value of the {@code Long}.
941 *
942 * @serial
943 */
944 private final long value;
945
946 /**
947 * Constructs a newly allocated {@code Long} object that
948 * represents the specified {@code long} argument.
949 *
950 * @param value the value to be represented by the
951 * {@code Long} object.
952 */
953 public Long(long value) {
954 this.value = value;
955 }
956
957 /**
958 * Constructs a newly allocated {@code Long} object that
959 * represents the {@code long} value indicated by the
960 * {@code String} parameter. The string is converted to a
961 * {@code long} value in exactly the manner used by the
962 * {@code parseLong} method for radix 10.
963 *
964 * @param s the {@code String} to be converted to a
965 * {@code Long}.
966 * @throws NumberFormatException if the {@code String} does not
967 * contain a parsable {@code long}.
968 * @see java.lang.Long#parseLong(java.lang.String, int)
969 */
970 public Long(String s) throws NumberFormatException {
971 this.value = parseLong(s, 10);
972 }
973
974 /**
975 * Returns the value of this {@code Long} as a {@code byte} after
976 * a narrowing primitive conversion.
977 * @jls 5.1.3 Narrowing Primitive Conversions
978 */
979 public byte byteValue() {
980 return (byte)value;
981 }
982
983 /**
984 * Returns the value of this {@code Long} as a {@code short} after
985 * a narrowing primitive conversion.
986 * @jls 5.1.3 Narrowing Primitive Conversions
987 */
988 public short shortValue() {
989 return (short)value;
990 }
991
992 /**
993 * Returns the value of this {@code Long} as an {@code int} after
994 * a narrowing primitive conversion.
995 * @jls 5.1.3 Narrowing Primitive Conversions
996 */
997 public int intValue() {
998 return (int)value;
999 }
1000
1001 /**
1002 * Returns the value of this {@code Long} as a
1003 * {@code long} value.
1004 */
1005 public long longValue() {
1006 return value;
1007 }
1008
1009 /**
1010 * Returns the value of this {@code Long} as a {@code float} after
1011 * a widening primitive conversion.
1012 * @jls 5.1.2 Widening Primitive Conversions
1013 */
1014 public float floatValue() {
1015 return (float)value;
1016 }
1017
1018 /**
1019 * Returns the value of this {@code Long} as a {@code double}
1020 * after a widening primitive conversion.
1021 * @jls 5.1.2 Widening Primitive Conversions
1022 */
1023 public double doubleValue() {
1024 return (double)value;
1025 }
1026
1027 /**
1028 * Returns a {@code String} object representing this
1029 * {@code Long}'s value. The value is converted to signed
1030 * decimal representation and returned as a string, exactly as if
1031 * the {@code long} value were given as an argument to the
1032 * {@link java.lang.Long#toString(long)} method.
1033 *
1034 * @return a string representation of the value of this object in
1035 * base 10.
1036 */
1037 public String toString() {
1038 return toString(value);
1039 }
1040
1041 /**
1042 * Returns a hash code for this {@code Long}. The result is
1043 * the exclusive OR of the two halves of the primitive
1044 * {@code long} value held by this {@code Long}
1045 * object. That is, the hashcode is the value of the expression:
1046 *
1047 * <blockquote>
1048 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1049 * </blockquote>
1050 *
1051 * @return a hash code value for this object.
1052 */
1053 @Override
1054 public int hashCode() {
1055 return Long.hashCode(value);
1056 }
1057
1058 /**
1059 * Returns a hash code for a {@code long} value; compatible with
1060 * {@code Long.hashCode()}.
1061 *
1062 * @param value the value to hash
1063 * @return a hash code value for a {@code long} value.
1064 * @since 1.8
1065 */
1066 public static int hashCode(long value) {
1067 return (int)(value ^ (value >>> 32));
1068 }
1069
1070 /**
1071 * Compares this object to the specified object. The result is
1072 * {@code true} if and only if the argument is not
1073 * {@code null} and is a {@code Long} object that
1074 * contains the same {@code long} value as this object.
1075 *
1076 * @param obj the object to compare with.
1077 * @return {@code true} if the objects are the same;
1078 * {@code false} otherwise.
1079 */
1080 public boolean equals(Object obj) {
1081 if (obj instanceof Long) {
1082 return value == ((Long)obj).longValue();
1083 }
1084 return false;
1085 }
1086
1087 /**
1088 * Determines the {@code long} value of the system property
1089 * with the specified name.
1090 *
1091 * <p>The first argument is treated as the name of a system
1092 * property. System properties are accessible through the {@link
1093 * java.lang.System#getProperty(java.lang.String)} method. The
1094 * string value of this property is then interpreted as a {@code
1095 * long} value using the grammar supported by {@link Long#decode decode}
1096 * and a {@code Long} object representing this value is returned.
1097 *
1098 * <p>If there is no property with the specified name, if the
1099 * specified name is empty or {@code null}, or if the property
1100 * does not have the correct numeric format, then {@code null} is
1101 * returned.
1102 *
1103 * <p>In other words, this method returns a {@code Long} object
1104 * equal to the value of:
1105 *
1106 * <blockquote>
1107 * {@code getLong(nm, null)}
1108 * </blockquote>
1109 *
1110 * @param nm property name.
1111 * @return the {@code Long} value of the property.
1112 * @throws SecurityException for the same reasons as
1113 * {@link System#getProperty(String) System.getProperty}
1114 * @see java.lang.System#getProperty(java.lang.String)
1115 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1116 */
1117 public static Long getLong(String nm) {
1118 return getLong(nm, null);
1119 }
1120
1121 /**
1122 * Determines the {@code long} value of the system property
1123 * with the specified name.
1124 *
1125 * <p>The first argument is treated as the name of a system
1126 * property. System properties are accessible through the {@link
1127 * java.lang.System#getProperty(java.lang.String)} method. The
1128 * string value of this property is then interpreted as a {@code
1129 * long} value using the grammar supported by {@link Long#decode decode}
1130 * and a {@code Long} object representing this value is returned.
1131 *
1132 * <p>The second argument is the default value. A {@code Long} object
1133 * that represents the value of the second argument is returned if there
1134 * is no property of the specified name, if the property does not have
1135 * the correct numeric format, or if the specified name is empty or null.
1136 *
1137 * <p>In other words, this method returns a {@code Long} object equal
1138 * to the value of:
1139 *
1140 * <blockquote>
1141 * {@code getLong(nm, new Long(val))}
1142 * </blockquote>
1143 *
1144 * but in practice it may be implemented in a manner such as:
1145 *
1146 * <blockquote><pre>
1147 * Long result = getLong(nm, null);
1148 * return (result == null) ? new Long(val) : result;
1149 * </pre></blockquote>
1150 *
1151 * to avoid the unnecessary allocation of a {@code Long} object when
1152 * the default value is not needed.
1153 *
1154 * @param nm property name.
1155 * @param val default value.
1156 * @return the {@code Long} value of the property.
1157 * @throws SecurityException for the same reasons as
1158 * {@link System#getProperty(String) System.getProperty}
1159 * @see java.lang.System#getProperty(java.lang.String)
1160 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1161 */
1162 public static Long getLong(String nm, long val) {
1163 Long result = Long.getLong(nm, null);
1164 return (result == null) ? Long.valueOf(val) : result;
1165 }
1166
1167 /**
1168 * Returns the {@code long} value of the system property with
1169 * the specified name. The first argument is treated as the name
1170 * of a system property. System properties are accessible through
1171 * the {@link java.lang.System#getProperty(java.lang.String)}
1172 * method. The string value of this property is then interpreted
1173 * as a {@code long} value, as per the
1174 * {@link Long#decode decode} method, and a {@code Long} object
1175 * representing this value is returned; in summary:
1176 *
1177 * <ul>
1178 * <li>If the property value begins with the two ASCII characters
1179 * {@code 0x} or the ASCII character {@code #}, not followed by
1180 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1181 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1182 * with radix 16.
1183 * <li>If the property value begins with the ASCII character
1184 * {@code 0} followed by another character, it is parsed as
1185 * an octal integer exactly as by the method {@link
1186 * #valueOf(java.lang.String, int)} with radix 8.
1187 * <li>Otherwise the property value is parsed as a decimal
1188 * integer exactly as by the method
1189 * {@link #valueOf(java.lang.String, int)} with radix 10.
1190 * </ul>
1191 *
1192 * <p>Note that, in every case, neither {@code L}
1193 * ({@code '\u005Cu004C'}) nor {@code l}
1194 * ({@code '\u005Cu006C'}) is permitted to appear at the end
1195 * of the property value as a type indicator, as would be
1196 * permitted in Java programming language source code.
1197 *
1198 * <p>The second argument is the default value. The default value is
1199 * returned if there is no property of the specified name, if the
1200 * property does not have the correct numeric format, or if the
1201 * specified name is empty or {@code null}.
1202 *
1203 * @param nm property name.
1204 * @param val default value.
1205 * @return the {@code Long} value of the property.
1206 * @throws SecurityException for the same reasons as
1207 * {@link System#getProperty(String) System.getProperty}
1208 * @see System#getProperty(java.lang.String)
1209 * @see System#getProperty(java.lang.String, java.lang.String)
1210 */
1211 public static Long getLong(String nm, Long val) {
1212 String v = null;
1213 try {
1214 v = System.getProperty(nm);
1215 } catch (IllegalArgumentException | NullPointerException e) {
1216 }
1217 if (v != null) {
1218 try {
1219 return Long.decode(v);
1220 } catch (NumberFormatException e) {
1221 }
1222 }
1223 return val;
1224 }
1225
1226 /**
1227 * Compares two {@code Long} objects numerically.
1228 *
1229 * @param anotherLong the {@code Long} to be compared.
1230 * @return the value {@code 0} if this {@code Long} is
1231 * equal to the argument {@code Long}; a value less than
1232 * {@code 0} if this {@code Long} is numerically less
1233 * than the argument {@code Long}; and a value greater
1234 * than {@code 0} if this {@code Long} is numerically
1235 * greater than the argument {@code Long} (signed
1236 * comparison).
1237 * @since 1.2
1238 */
1239 public int compareTo(Long anotherLong) {
1240 return compare(this.value, anotherLong.value);
1241 }
1242
1243 /**
1244 * Compares two {@code long} values numerically.
1245 * The value returned is identical to what would be returned by:
1246 * <pre>
1247 * Long.valueOf(x).compareTo(Long.valueOf(y))
1248 * </pre>
1249 *
1250 * @param x the first {@code long} to compare
1251 * @param y the second {@code long} to compare
1252 * @return the value {@code 0} if {@code x == y};
1253 * a value less than {@code 0} if {@code x < y}; and
1254 * a value greater than {@code 0} if {@code x > y}
1255 * @since 1.7
1256 */
1257 public static int compare(long x, long y) {
1258 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1259 }
1260
1261 /**
1262 * Compares two {@code long} values numerically treating the values
1263 * as unsigned.
1264 *
1265 * @param x the first {@code long} to compare
1266 * @param y the second {@code long} to compare
1267 * @return the value {@code 0} if {@code x == y}; a value less
1268 * than {@code 0} if {@code x < y} as unsigned values; and
1269 * a value greater than {@code 0} if {@code x > y} as
1270 * unsigned values
1271 * @since 1.8
1272 */
1273 public static int compareUnsigned(long x, long y) {
1274 return compare(x + MIN_VALUE, y + MIN_VALUE);
1275 }
1276
1277
1278 /**
1279 * Returns the unsigned quotient of dividing the first argument by
1280 * the second where each argument and the result is interpreted as
1281 * an unsigned value.
1282 *
1283 * <p>Note that in two's complement arithmetic, the three other
1284 * basic arithmetic operations of add, subtract, and multiply are
1285 * bit-wise identical if the two operands are regarded as both
1286 * being signed or both being unsigned. Therefore separate {@code
1287 * addUnsigned}, etc. methods are not provided.
1288 *
1289 * @param dividend the value to be divided
1290 * @param divisor the value doing the dividing
1291 * @return the unsigned quotient of the first argument divided by
1292 * the second argument
1293 * @see #remainderUnsigned
1294 * @since 1.8
1295 */
1296 public static long divideUnsigned(long dividend, long divisor) {
1297 if (divisor < 0L) { // signed comparison
1298 // Answer must be 0 or 1 depending on relative magnitude
1299 // of dividend and divisor.
1300 return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;
1301 }
1302
1303 if (dividend > 0) // Both inputs non-negative
1304 return dividend/divisor;
1305 else {
1306 /*
1307 * For simple code, leveraging BigInteger. Longer and faster
1308 * code written directly in terms of operations on longs is
1309 * possible; see "Hacker's Delight" for divide and remainder
1310 * algorithms.
1311 */
1312 return toUnsignedBigInteger(dividend).
1313 divide(toUnsignedBigInteger(divisor)).longValue();
1314 }
1315 }
1316
1317 /**
1318 * Returns the unsigned remainder from dividing the first argument
1319 * by the second where each argument and the result is interpreted
1320 * as an unsigned value.
1321 *
1322 * @param dividend the value to be divided
1323 * @param divisor the value doing the dividing
1324 * @return the unsigned remainder of the first argument divided by
1325 * the second argument
1326 * @see #divideUnsigned
1327 * @since 1.8
1328 */
1329 public static long remainderUnsigned(long dividend, long divisor) {
1330 if (dividend > 0 && divisor > 0) { // signed comparisons
1331 return dividend % divisor;
1332 } else {
1333 if (compareUnsigned(dividend, divisor) < 0) // Avoid explicit check for 0 divisor
1334 return dividend;
1335 else
1336 return toUnsignedBigInteger(dividend).
1337 remainder(toUnsignedBigInteger(divisor)).longValue();
1338 }
1339 }
1340
1341 // Bit Twiddling
1342
1343 /**
1344 * The number of bits used to represent a {@code long} value in two's
1345 * complement binary form.
1346 *
1347 * @since 1.5
1348 */
1349 @Native public static final int SIZE = 64;
1350
1351 /**
1352 * The number of bytes used to represent a {@code long} value in two's
1353 * complement binary form.
1354 *
1355 * @since 1.8
1356 */
1357 public static final int BYTES = SIZE / Byte.SIZE;
1358
1359 /**
1360 * Returns a {@code long} value with at most a single one-bit, in the
1361 * position of the highest-order ("leftmost") one-bit in the specified
1362 * {@code long} value. Returns zero if the specified value has no
1363 * one-bits in its two's complement binary representation, that is, if it
1364 * is equal to zero.
1365 *
1366 * @param i the value whose highest one bit is to be computed
1367 * @return a {@code long} value with a single one-bit, in the position
1368 * of the highest-order one-bit in the specified value, or zero if
1369 * the specified value is itself equal to zero.
1370 * @since 1.5
1371 */
1372 public static long highestOneBit(long i) {
1373 // HD, Figure 3-1
1374 i |= (i >> 1);
1375 i |= (i >> 2);
1376 i |= (i >> 4);
1377 i |= (i >> 8);
1378 i |= (i >> 16);
1379 i |= (i >> 32);
1380 return i - (i >>> 1);
1381 }
1382
1383 /**
1384 * Returns a {@code long} value with at most a single one-bit, in the
1385 * position of the lowest-order ("rightmost") one-bit in the specified
1386 * {@code long} value. Returns zero if the specified value has no
1387 * one-bits in its two's complement binary representation, that is, if it
1388 * is equal to zero.
1389 *
1390 * @param i the value whose lowest one bit is to be computed
1391 * @return a {@code long} value with a single one-bit, in the position
1392 * of the lowest-order one-bit in the specified value, or zero if
1393 * the specified value is itself equal to zero.
1394 * @since 1.5
1395 */
1396 public static long lowestOneBit(long i) {
1397 // HD, Section 2-1
1398 return i & -i;
1399 }
1400
1401 /**
1402 * Returns the number of zero bits preceding the highest-order
1403 * ("leftmost") one-bit in the two's complement binary representation
1404 * of the specified {@code long} value. Returns 64 if the
1405 * specified value has no one-bits in its two's complement representation,
1406 * in other words if it is equal to zero.
1407 *
1408 * <p>Note that this method is closely related to the logarithm base 2.
1409 * For all positive {@code long} values x:
1410 * <ul>
1411 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1412 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1413 * </ul>
1414 *
1415 * @param i the value whose number of leading zeros is to be computed
1416 * @return the number of zero bits preceding the highest-order
1417 * ("leftmost") one-bit in the two's complement binary representation
1418 * of the specified {@code long} value, or 64 if the value
1419 * is equal to zero.
1420 * @since 1.5
1421 */
1422 public static int numberOfLeadingZeros(long i) {
1423 // HD, Figure 5-6
1424 if (i == 0)
1425 return 64;
1426 int n = 1;
1427 int x = (int)(i >>> 32);
1428 if (x == 0) { n += 32; x = (int)i; }
1429 if (x >>> 16 == 0) { n += 16; x <<= 16; }
1430 if (x >>> 24 == 0) { n += 8; x <<= 8; }
1431 if (x >>> 28 == 0) { n += 4; x <<= 4; }
1432 if (x >>> 30 == 0) { n += 2; x <<= 2; }
1433 n -= x >>> 31;
1434 return n;
1435 }
1436
1437 /**
1438 * Returns the number of zero bits following the lowest-order ("rightmost")
1439 * one-bit in the two's complement binary representation of the specified
1440 * {@code long} value. Returns 64 if the specified value has no
1441 * one-bits in its two's complement representation, in other words if it is
1442 * equal to zero.
1443 *
1444 * @param i the value whose number of trailing zeros is to be computed
1445 * @return the number of zero bits following the lowest-order ("rightmost")
1446 * one-bit in the two's complement binary representation of the
1447 * specified {@code long} value, or 64 if the value is equal
1448 * to zero.
1449 * @since 1.5
1450 */
1451 public static int numberOfTrailingZeros(long i) {
1452 // HD, Figure 5-14
1453 int x, y;
1454 if (i == 0) return 64;
1455 int n = 63;
1456 y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
1457 y = x <<16; if (y != 0) { n = n -16; x = y; }
1458 y = x << 8; if (y != 0) { n = n - 8; x = y; }
1459 y = x << 4; if (y != 0) { n = n - 4; x = y; }
1460 y = x << 2; if (y != 0) { n = n - 2; x = y; }
1461 return n - ((x << 1) >>> 31);
1462 }
1463
1464 /**
1465 * Returns the number of one-bits in the two's complement binary
1466 * representation of the specified {@code long} value. This function is
1467 * sometimes referred to as the <i>population count</i>.
1468 *
1469 * @param i the value whose bits are to be counted
1470 * @return the number of one-bits in the two's complement binary
1471 * representation of the specified {@code long} value.
1472 * @since 1.5
1473 */
1474 public static int bitCount(long i) {
1475 // HD, Figure 5-14
1476 i = i - ((i >>> 1) & 0x5555555555555555L);
1477 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1478 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1479 i = i + (i >>> 8);
1480 i = i + (i >>> 16);
1481 i = i + (i >>> 32);
1482 return (int)i & 0x7f;
1483 }
1484
1485 /**
1486 * Returns the value obtained by rotating the two's complement binary
1487 * representation of the specified {@code long} value left by the
1488 * specified number of bits. (Bits shifted out of the left hand, or
1489 * high-order, side reenter on the right, or low-order.)
1490 *
1491 * <p>Note that left rotation with a negative distance is equivalent to
1492 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1493 * distance)}. Note also that rotation by any multiple of 64 is a
1494 * no-op, so all but the last six bits of the rotation distance can be
1495 * ignored, even if the distance is negative: {@code rotateLeft(val,
1496 * distance) == rotateLeft(val, distance & 0x3F)}.
1497 *
1498 * @param i the value whose bits are to be rotated left
1499 * @param distance the number of bit positions to rotate left
1500 * @return the value obtained by rotating the two's complement binary
1501 * representation of the specified {@code long} value left by the
1502 * specified number of bits.
1503 * @since 1.5
1504 */
1505 public static long rotateLeft(long i, int distance) {
1506 return (i << distance) | (i >>> -distance);
1507 }
1508
1509 /**
1510 * Returns the value obtained by rotating the two's complement binary
1511 * representation of the specified {@code long} value right by the
1512 * specified number of bits. (Bits shifted out of the right hand, or
1513 * low-order, side reenter on the left, or high-order.)
1514 *
1515 * <p>Note that right rotation with a negative distance is equivalent to
1516 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1517 * distance)}. Note also that rotation by any multiple of 64 is a
1518 * no-op, so all but the last six bits of the rotation distance can be
1519 * ignored, even if the distance is negative: {@code rotateRight(val,
1520 * distance) == rotateRight(val, distance & 0x3F)}.
1521 *
1522 * @param i the value whose bits are to be rotated right
1523 * @param distance the number of bit positions to rotate right
1524 * @return the value obtained by rotating the two's complement binary
1525 * representation of the specified {@code long} value right by the
1526 * specified number of bits.
1527 * @since 1.5
1528 */
1529 public static long rotateRight(long i, int distance) {
1530 return (i >>> distance) | (i << -distance);
1531 }
1532
1533 /**
1534 * Returns the value obtained by reversing the order of the bits in the
1535 * two's complement binary representation of the specified {@code long}
1536 * value.
1537 *
1538 * @param i the value to be reversed
1539 * @return the value obtained by reversing order of the bits in the
1540 * specified {@code long} value.
1541 * @since 1.5
1542 */
1543 public static long reverse(long i) {
1544 // HD, Figure 7-1
1545 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1546 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1547 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1548 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1549 i = (i << 48) | ((i & 0xffff0000L) << 16) |
1550 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1551 return i;
1552 }
1553
1554 /**
1555 * Returns the signum function of the specified {@code long} value. (The
1556 * return value is -1 if the specified value is negative; 0 if the
1557 * specified value is zero; and 1 if the specified value is positive.)
1558 *
1559 * @param i the value whose signum is to be computed
1560 * @return the signum function of the specified {@code long} value.
1561 * @since 1.5
1562 */
1563 public static int signum(long i) {
1564 // HD, Section 2-7
1565 return (int) ((i >> 63) | (-i >>> 63));
1566 }
1567
1568 /**
1569 * Returns the value obtained by reversing the order of the bytes in the
1570 * two's complement representation of the specified {@code long} value.
1571 *
1572 * @param i the value whose bytes are to be reversed
1573 * @return the value obtained by reversing the bytes in the specified
1574 * {@code long} value.
1575 * @since 1.5
1576 */
1577 public static long reverseBytes(long i) {
1578 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1579 return (i << 48) | ((i & 0xffff0000L) << 16) |
1580 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1581 }
1582
1583 /**
1584 * Adds two {@code long} values together as per the + operator.
1585 *
1586 * @param a the first operand
1587 * @param b the second operand
1588 * @return the sum of {@code a} and {@code b}
1589 * @see java.util.function.BinaryOperator
1590 * @since 1.8
1591 */
1592 public static long sum(long a, long b) {
1593 return a + b;
1594 }
1595
1596 /**
1597 * Returns the greater of two {@code long} values
1598 * as if by calling {@link Math#max(long, long) Math.max}.
1599 *
1600 * @param a the first operand
1601 * @param b the second operand
1602 * @return the greater of {@code a} and {@code b}
1603 * @see java.util.function.BinaryOperator
1604 * @since 1.8
1605 */
1606 public static long max(long a, long b) {
1607 return Math.max(a, b);
1608 }
1609
1610 /**
1611 * Returns the smaller of two {@code long} values
1612 * as if by calling {@link Math#min(long, long) Math.min}.
1613 *
1614 * @param a the first operand
1615 * @param b the second operand
1616 * @return the smaller of {@code a} and {@code b}
1617 * @see java.util.function.BinaryOperator
1618 * @since 1.8
1619 */
1620 public static long min(long a, long b) {
1621 return Math.min(a, b);
1622 }
1623
1624 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1625 @Native private static final long serialVersionUID = 4290774380558885855L;
1626 }