1 /*
2 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import java.lang.annotation.Native;
29 import java.math.*;
30
31
32 /**
33 * The {@code Long} class wraps a value of the primitive type {@code
34 * long} in an object. An object of type {@code Long} contains a
35 * single field whose type is {@code long}.
36 *
37 * <p> In addition, this class provides several methods for converting
38 * a {@code long} to a {@code String} and a {@code String} to a {@code
39 * long}, as well as other constants and methods useful when dealing
40 * with a {@code long}.
41 *
42 * <p>Implementation note: The implementations of the "bit twiddling"
43 * methods (such as {@link #highestOneBit(long) highestOneBit} and
44 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
45 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
46 * Delight</i>, (Addison Wesley, 2002).
47 *
48 * @author Lee Boynton
49 * @author Arthur van Hoff
50 * @author Josh Bloch
51 * @author Joseph D. Darcy
52 * @since 1.0
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 1.1
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 * @see #toHexString(long, int)
270 * @since 1.0.2
271 */
272 public static String toHexString(long i) {
273 return toUnsignedString0(i, 4);
274 }
275
276 /**
277 * Returns a string representation of the {@code long}
278 * argument as an unsigned integer in base 16, padded with
279 * leading zeroes if necessary.
280 *
281 * <p>The unsigned {@code long} value is the argument plus
282 * 2<sup>64</sup> if the argument is negative; otherwise, it is
283 * equal to the argument. This value is converted to a string of
284 * ASCII digits in hexadecimal (base 16) with possibly
285 * appended leading zeroes. A minimum amount of zeroes is appended
286 * to ensure the length of the resulting string is at least
287 * {@code minWidth}.
288 *
289 * <p>The value of the argument can be recovered from the returned
290 * string {@code s} by calling {@link
291 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
292 * 16)}.
293 *
294 * <p>If the unsigned magnitude is zero, it is represented by a
295 * single zero character {@code '0'} ({@code '\u005Cu0030'}).
296 * The following characters are used as hexadecimal digits:
297 *
298 * <blockquote>
299 * {@code 0123456789abcdef}
300 * </blockquote>
301 *
302 * These are the characters {@code '\u005Cu0030'} through
303 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
304 * {@code '\u005Cu0066'}. If uppercase letters are desired,
305 * the {@link java.lang.String#toUpperCase()} method may be called
306 * on the result:
307 *
308 * <blockquote>
309 * {@code Long.toHexString(n, 12).toUpperCase()}
310 * </blockquote>
311 *
312 * @param i a {@code long} to be converted to a string.
313 * @param minWidth a minimum required length of the resulting string.
314 * @return the string representation of the unsigned {@code long}
315 * value represented by the argument in hexadecimal
316 * (base 16), padded with leading zeroes if necessary.
317 * @see #parseUnsignedLong(String, int)
318 * @see #toUnsignedString(long, int)
319 * @see #toHexString(long)
320 * @since 1.9
321 */
322 public static String toHexString(long i, int minWidth) {
323 return toUnsignedString0(i, 4, minWidth);
324 }
325
326 /**
327 * Returns a string representation of the {@code long}
328 * argument as an unsigned integer in base 8.
329 *
330 * <p>The unsigned {@code long} value is the argument plus
331 * 2<sup>64</sup> if the argument is negative; otherwise, it is
332 * equal to the argument. This value is converted to a string of
333 * ASCII digits in octal (base 8) with no extra leading
334 * {@code 0}s.
335 *
336 * <p>The value of the argument can be recovered from the returned
337 * string {@code s} by calling {@link
338 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
339 * 8)}.
340 *
341 * <p>If the unsigned magnitude is zero, it is represented by a
342 * single zero character {@code '0'} ({@code '\u005Cu0030'});
343 * otherwise, the first character of the representation of the
344 * unsigned magnitude will not be the zero character. The
345 * following characters are used as octal digits:
346 *
347 * <blockquote>
348 * {@code 01234567}
349 * </blockquote>
350 *
351 * These are the characters {@code '\u005Cu0030'} through
352 * {@code '\u005Cu0037'}.
353 *
354 * @param i a {@code long} to be converted to a string.
355 * @return the string representation of the unsigned {@code long}
356 * value represented by the argument in octal (base 8).
357 * @see #parseUnsignedLong(String, int)
358 * @see #toUnsignedString(long, int)
359 * @since 1.0.2
360 */
361 public static String toOctalString(long i) {
362 return toUnsignedString0(i, 3);
363 }
364
365 /**
366 * Returns a string representation of the {@code long}
367 * argument as an unsigned integer in base 2.
368 *
369 * <p>The unsigned {@code long} value is the argument plus
370 * 2<sup>64</sup> if the argument is negative; otherwise, it is
371 * equal to the argument. This value is converted to a string of
372 * ASCII digits in binary (base 2) with no extra leading
373 * {@code 0}s.
374 *
375 * <p>The value of the argument can be recovered from the returned
376 * string {@code s} by calling {@link
377 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
378 * 2)}.
379 *
380 * <p>If the unsigned magnitude is zero, it is represented by a
381 * single zero character {@code '0'} ({@code '\u005Cu0030'});
382 * otherwise, the first character of the representation of the
383 * unsigned magnitude will not be the zero character. The
384 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
385 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
386 *
387 * @param i a {@code long} to be converted to a string.
388 * @return the string representation of the unsigned {@code long}
389 * value represented by the argument in binary (base 2).
390 * @see #parseUnsignedLong(String, int)
391 * @see #toUnsignedString(long, int)
392 * @since 1.0.2
393 */
394 public static String toBinaryString(long i) {
395 return toUnsignedString0(i, 1);
396 }
397
398 /**
399 * Format a long (treated as unsigned) into a String.
400 * @param val the value to format
401 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
402 */
403 static String toUnsignedString0(long val, int shift) {
404 // assert shift > 0 && shift <=5 : "Illegal shift value";
405 int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
406 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
407 char[] buf = new char[chars];
408
409 formatUnsignedLong(val, shift, buf, 0, chars);
410 return new String(buf, true);
411 }
412
413 /**
414 * Format a long (treated as unsigned) into a String.
415 * @param val the value to format
416 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
417 * @param minWidth the minimum width of the produced String
418 */
419 static String toUnsignedString0(long val, int shift, int minWidth) {
420 int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
421 int magLen = (mag + (shift - 1)) / shift;
422 int zeroes = Math.max(Math.max(minWidth, 1) - magLen, 0);
423 char[] buf = new char[magLen + zeroes];
424
425 for (int i = 0; i < zeroes; ++i)
426 buf[i] = '0';
427 if (magLen > 0)
428 formatUnsignedLong(val, shift, buf, zeroes, magLen);
429 return new String(buf, true);
430 }
431
432 /**
433 * Format a long (treated as unsigned) into a character buffer.
434 * @param val the unsigned long to format
435 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
436 * @param buf the character buffer to write to
437 * @param offset the offset in the destination buffer to start at
438 * @param len the number of characters to write
439 * @return the lowest character location used
440 */
441 static int formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
442 int charPos = len;
443 int radix = 1 << shift;
444 int mask = radix - 1;
445 do {
446 buf[offset + --charPos] = Integer.digits[((int) val) & mask];
447 val >>>= shift;
448 } while (val != 0 && charPos > 0);
449
450 return charPos;
451 }
452
453 /**
454 * Returns a {@code String} object representing the specified
455 * {@code long}. The argument is converted to signed decimal
456 * representation and returned as a string, exactly as if the
457 * argument and the radix 10 were given as arguments to the {@link
458 * #toString(long, int)} method.
459 *
460 * @param i a {@code long} to be converted.
461 * @return a string representation of the argument in base 10.
462 */
463 public static String toString(long i) {
464 if (i == Long.MIN_VALUE)
465 return "-9223372036854775808";
466 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
467 char[] buf = new char[size];
468 getChars(i, size, buf);
469 return new String(buf, true);
470 }
471
472 /**
473 * Returns a string representation of the argument as an unsigned
474 * decimal value.
475 *
476 * The argument is converted to unsigned decimal representation
477 * and returned as a string exactly as if the argument and radix
478 * 10 were given as arguments to the {@link #toUnsignedString(long,
479 * int)} method.
480 *
481 * @param i an integer to be converted to an unsigned string.
482 * @return an unsigned string representation of the argument.
483 * @see #toUnsignedString(long, int)
484 * @since 1.8
485 */
486 public static String toUnsignedString(long i) {
487 return toUnsignedString(i, 10);
488 }
489
490 /**
491 * Places characters representing the integer i into the
492 * character array buf. The characters are placed into
493 * the buffer backwards starting with the least significant
494 * digit at the specified index (exclusive), and working
495 * backwards from there.
496 *
497 * Will fail if i == Long.MIN_VALUE
498 */
499 static void getChars(long i, int index, char[] buf) {
500 long q;
501 int r;
502 int charPos = index;
503 char sign = 0;
504
505 if (i < 0) {
506 sign = '-';
507 i = -i;
508 }
509
510 // Get 2 digits/iteration using longs until quotient fits into an int
511 while (i > Integer.MAX_VALUE) {
512 q = i / 100;
513 // really: r = i - (q * 100);
514 r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
515 i = q;
516 buf[--charPos] = Integer.DigitOnes[r];
517 buf[--charPos] = Integer.DigitTens[r];
518 }
519
520 // Get 2 digits/iteration using ints
521 int q2;
522 int i2 = (int)i;
523 while (i2 >= 65536) {
524 q2 = i2 / 100;
525 // really: r = i2 - (q * 100);
526 r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
527 i2 = q2;
528 buf[--charPos] = Integer.DigitOnes[r];
529 buf[--charPos] = Integer.DigitTens[r];
530 }
531
532 // Fall thru to fast mode for smaller numbers
533 // assert(i2 <= 65536, i2);
534 for (;;) {
535 q2 = (i2 * 52429) >>> (16+3);
536 r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
537 buf[--charPos] = Integer.digits[r];
538 i2 = q2;
539 if (i2 == 0) break;
540 }
541 if (sign != 0) {
542 buf[--charPos] = sign;
543 }
544 }
545
546 // Requires positive x
547 static int stringSize(long x) {
548 long p = 10;
549 for (int i=1; i<19; i++) {
550 if (x < p)
551 return i;
552 p = 10*p;
553 }
554 return 19;
555 }
556
557 /**
558 * Parses the string argument as a signed {@code long} in the
559 * radix specified by the second argument. The characters in the
560 * string must all be digits of the specified radix (as determined
561 * by whether {@link java.lang.Character#digit(char, int)} returns
562 * a nonnegative value), except that the first character may be an
563 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
564 * indicate a negative value or an ASCII plus sign {@code '+'}
565 * ({@code '\u005Cu002B'}) to indicate a positive value. The
566 * resulting {@code long} value is returned.
567 *
568 * <p>Note that neither the character {@code L}
569 * ({@code '\u005Cu004C'}) nor {@code l}
570 * ({@code '\u005Cu006C'}) is permitted to appear at the end
571 * of the string as a type indicator, as would be permitted in
572 * Java programming language source code - except that either
573 * {@code L} or {@code l} may appear as a digit for a
574 * radix greater than or equal to 22.
575 *
576 * <p>An exception of type {@code NumberFormatException} is
577 * thrown if any of the following situations occurs:
578 * <ul>
579 *
580 * <li>The first argument is {@code null} or is a string of
581 * length zero.
582 *
583 * <li>The {@code radix} is either smaller than {@link
584 * java.lang.Character#MIN_RADIX} or larger than {@link
585 * java.lang.Character#MAX_RADIX}.
586 *
587 * <li>Any character of the string is not a digit of the specified
588 * radix, except that the first character may be a minus sign
589 * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
590 * '+'} ({@code '\u005Cu002B'}) provided that the string is
591 * longer than length 1.
592 *
593 * <li>The value represented by the string is not a value of type
594 * {@code long}.
595 * </ul>
596 *
597 * <p>Examples:
598 * <blockquote><pre>
599 * parseLong("0", 10) returns 0L
600 * parseLong("473", 10) returns 473L
601 * parseLong("+42", 10) returns 42L
602 * parseLong("-0", 10) returns 0L
603 * parseLong("-FF", 16) returns -255L
604 * parseLong("1100110", 2) returns 102L
605 * parseLong("99", 8) throws a NumberFormatException
606 * parseLong("Hazelnut", 10) throws a NumberFormatException
607 * parseLong("Hazelnut", 36) returns 1356099454469L
608 * </pre></blockquote>
609 *
610 * @param s the {@code String} containing the
611 * {@code long} representation to be parsed.
612 * @param radix the radix to be used while parsing {@code s}.
613 * @return the {@code long} represented by the string argument in
614 * the specified radix.
615 * @throws NumberFormatException if the string does not contain a
616 * parsable {@code long}.
617 */
618 public static long parseLong(String s, int radix)
619 throws NumberFormatException
620 {
621 if (s == null) {
622 throw new NumberFormatException("null");
623 }
624
625 if (radix < Character.MIN_RADIX) {
626 throw new NumberFormatException("radix " + radix +
627 " less than Character.MIN_RADIX");
628 }
629 if (radix > Character.MAX_RADIX) {
630 throw new NumberFormatException("radix " + radix +
631 " greater than Character.MAX_RADIX");
632 }
633
634 long result = 0;
635 boolean negative = false;
636 int i = 0, len = s.length();
637 long limit = -Long.MAX_VALUE;
638 long multmin;
639 int digit;
640
641 if (len > 0) {
642 char firstChar = s.charAt(0);
643 if (firstChar < '0') { // Possible leading "+" or "-"
644 if (firstChar == '-') {
645 negative = true;
646 limit = Long.MIN_VALUE;
647 } else if (firstChar != '+')
648 throw NumberFormatException.forInputString(s);
649
650 if (len == 1) // Cannot have lone "+" or "-"
651 throw NumberFormatException.forInputString(s);
652 i++;
653 }
654 multmin = limit / radix;
655 while (i < len) {
656 // Accumulating negatively avoids surprises near MAX_VALUE
657 digit = Character.digit(s.charAt(i++),radix);
658 if (digit < 0) {
659 throw NumberFormatException.forInputString(s);
660 }
661 if (result < multmin) {
662 throw NumberFormatException.forInputString(s);
663 }
664 result *= radix;
665 if (result < limit + digit) {
666 throw NumberFormatException.forInputString(s);
667 }
668 result -= digit;
669 }
670 } else {
671 throw NumberFormatException.forInputString(s);
672 }
673 return negative ? result : -result;
674 }
675
676 /**
677 * Parses the string argument as a signed decimal {@code long}.
678 * The characters in the string must all be decimal digits, except
679 * that the first character may be an ASCII minus sign {@code '-'}
680 * ({@code \u005Cu002D'}) to indicate a negative value or an
681 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
682 * indicate a positive value. The resulting {@code long} value is
683 * returned, exactly as if the argument and the radix {@code 10}
684 * were given as arguments to the {@link
685 * #parseLong(java.lang.String, int)} method.
686 *
687 * <p>Note that neither the character {@code L}
688 * ({@code '\u005Cu004C'}) nor {@code l}
689 * ({@code '\u005Cu006C'}) is permitted to appear at the end
690 * of the string as a type indicator, as would be permitted in
691 * Java programming language source code.
692 *
693 * @param s a {@code String} containing the {@code long}
694 * representation to be parsed
695 * @return the {@code long} represented by the argument in
696 * decimal.
697 * @throws NumberFormatException if the string does not contain a
698 * parsable {@code long}.
699 */
700 public static long parseLong(String s) throws NumberFormatException {
701 return parseLong(s, 10);
702 }
703
704 /**
705 * Parses the string argument as an unsigned {@code long} in the
706 * radix specified by the second argument. An unsigned integer
707 * maps the values usually associated with negative numbers to
708 * positive numbers larger than {@code MAX_VALUE}.
709 *
710 * The characters in the string must all be digits of the
711 * specified radix (as determined by whether {@link
712 * java.lang.Character#digit(char, int)} returns a nonnegative
713 * value), except that the first character may be an ASCII plus
714 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
715 * integer value is returned.
716 *
717 * <p>An exception of type {@code NumberFormatException} is
718 * thrown if any of the following situations occurs:
719 * <ul>
720 * <li>The first argument is {@code null} or is a string of
721 * length zero.
722 *
723 * <li>The radix is either smaller than
724 * {@link java.lang.Character#MIN_RADIX} or
725 * larger than {@link java.lang.Character#MAX_RADIX}.
726 *
727 * <li>Any character of the string is not a digit of the specified
728 * radix, except that the first character may be a plus sign
729 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
730 * string is longer than length 1.
731 *
732 * <li>The value represented by the string is larger than the
733 * largest unsigned {@code long}, 2<sup>64</sup>-1.
734 *
735 * </ul>
736 *
737 *
738 * @param s the {@code String} containing the unsigned integer
739 * representation to be parsed
740 * @param radix the radix to be used while parsing {@code s}.
741 * @return the unsigned {@code long} represented by the string
742 * argument in the specified radix.
743 * @throws NumberFormatException if the {@code String}
744 * does not contain a parsable {@code long}.
745 * @since 1.8
746 */
747 public static long parseUnsignedLong(String s, int radix)
748 throws NumberFormatException {
749 if (s == null) {
750 throw new NumberFormatException("null");
751 }
752
753 int len = s.length();
754 if (len > 0) {
755 char firstChar = s.charAt(0);
756 if (firstChar == '-') {
757 throw new
758 NumberFormatException(String.format("Illegal leading minus sign " +
759 "on unsigned string %s.", s));
760 } else {
761 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
762 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
763 return parseLong(s, radix);
764 }
765
766 // No need for range checks on len due to testing above.
767 long first = parseLong(s.substring(0, len - 1), radix);
768 int second = Character.digit(s.charAt(len - 1), radix);
769 if (second < 0) {
770 throw new NumberFormatException("Bad digit at end of " + s);
771 }
772 long result = first * radix + second;
773
774 /*
775 * Test leftmost bits of multiprecision extension of first*radix
776 * for overflow. The number of bits needed is defined by
777 * GUARD_BIT = ceil(log2(Character.MAX_RADIX)) + 1 = 7. Then
778 * int guard = radix*(int)(first >>> (64 - GUARD_BIT)) and
779 * overflow is tested by splitting guard in the ranges
780 * guard < 92, 92 <= guard < 128, and 128 <= guard, where
781 * 92 = 128 - Character.MAX_RADIX. Note that guard cannot take
782 * on a value which does not include a prime factor in the legal
783 * radix range.
784 */
785 int guard = radix * (int) (first >>> 57);
786 if (guard >= 128 ||
787 (result >= 0 && guard >= 128 - Character.MAX_RADIX)) {
788 /*
789 * For purposes of exposition, the programmatic statements
790 * below should be taken to be multi-precision, i.e., not
791 * subject to overflow.
792 *
793 * A) Condition guard >= 128:
794 * If guard >= 128 then first*radix >= 2^7 * 2^57 = 2^64
795 * hence always overflow.
796 *
797 * B) Condition guard < 92:
798 * Define left7 = first >>> 57.
799 * Given first = (left7 * 2^57) + (first & (2^57 - 1)) then
800 * result <= (radix*left7)*2^57 + radix*(2^57 - 1) + second.
801 * Thus if radix*left7 < 92, radix <= 36, and second < 36,
802 * then result < 92*2^57 + 36*(2^57 - 1) + 36 = 2^64 hence
803 * never overflow.
804 *
805 * C) Condition 92 <= guard < 128:
806 * first*radix + second >= radix*left7*2^57 + second
807 * so that first*radix + second >= 92*2^57 + 0 > 2^63
808 *
809 * D) Condition guard < 128:
810 * radix*first <= (radix*left7) * 2^57 + radix*(2^57 - 1)
811 * so
812 * radix*first + second <= (radix*left7) * 2^57 + radix*(2^57 - 1) + 36
813 * thus
814 * radix*first + second < 128 * 2^57 + 36*2^57 - radix + 36
815 * whence
816 * radix*first + second < 2^64 + 2^6*2^57 = 2^64 + 2^63
817 *
818 * E) Conditions C, D, and result >= 0:
819 * C and D combined imply the mathematical result
820 * 2^63 < first*radix + second < 2^64 + 2^63. The lower
821 * bound is therefore negative as a signed long, but the
822 * upper bound is too small to overflow again after the
823 * signed long overflows to positive above 2^64 - 1. Hence
824 * result >= 0 implies overflow given C and D.
825 */
826 throw new NumberFormatException(String.format("String value %s exceeds " +
827 "range of unsigned long.", s));
828 }
829 return result;
830 }
831 } else {
832 throw NumberFormatException.forInputString(s);
833 }
834 }
835
836 /**
837 * Parses the string argument as an unsigned decimal {@code long}. The
838 * characters in the string must all be decimal digits, except
839 * that the first character may be an an ASCII plus sign {@code
840 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
841 * is returned, exactly as if the argument and the radix 10 were
842 * given as arguments to the {@link
843 * #parseUnsignedLong(java.lang.String, int)} method.
844 *
845 * @param s a {@code String} containing the unsigned {@code long}
846 * representation to be parsed
847 * @return the unsigned {@code long} value represented by the decimal string argument
848 * @throws NumberFormatException if the string does not contain a
849 * parsable unsigned integer.
850 * @since 1.8
851 */
852 public static long parseUnsignedLong(String s) throws NumberFormatException {
853 return parseUnsignedLong(s, 10);
854 }
855
856 /**
857 * Returns a {@code Long} object holding the value
858 * extracted from the specified {@code String} when parsed
859 * with the radix given by the second argument. The first
860 * argument is interpreted as representing a signed
861 * {@code long} in the radix specified by the second
862 * argument, exactly as if the arguments were given to the {@link
863 * #parseLong(java.lang.String, int)} method. The result is a
864 * {@code Long} object that represents the {@code long}
865 * value specified by the string.
866 *
867 * <p>In other words, this method returns a {@code Long} object equal
868 * to the value of:
869 *
870 * <blockquote>
871 * {@code new Long(Long.parseLong(s, radix))}
872 * </blockquote>
873 *
874 * @param s the string to be parsed
875 * @param radix the radix to be used in interpreting {@code s}
876 * @return a {@code Long} object holding the value
877 * represented by the string argument in the specified
878 * radix.
879 * @throws NumberFormatException If the {@code String} does not
880 * contain a parsable {@code long}.
881 */
882 public static Long valueOf(String s, int radix) throws NumberFormatException {
883 return Long.valueOf(parseLong(s, radix));
884 }
885
886 /**
887 * Returns a {@code Long} object holding the value
888 * of the specified {@code String}. The argument is
889 * interpreted as representing a signed decimal {@code long},
890 * exactly as if the argument were given to the {@link
891 * #parseLong(java.lang.String)} method. The result is a
892 * {@code Long} object that represents the integer value
893 * specified by the string.
894 *
895 * <p>In other words, this method returns a {@code Long} object
896 * equal to the value of:
897 *
898 * <blockquote>
899 * {@code new Long(Long.parseLong(s))}
900 * </blockquote>
901 *
902 * @param s the string to be parsed.
903 * @return a {@code Long} object holding the value
904 * represented by the string argument.
905 * @throws NumberFormatException If the string cannot be parsed
906 * as a {@code long}.
907 */
908 public static Long valueOf(String s) throws NumberFormatException
909 {
910 return Long.valueOf(parseLong(s, 10));
911 }
912
913 private static class LongCache {
914 private LongCache(){}
915
916 static final Long cache[] = new Long[-(-128) + 127 + 1];
917
918 static {
919 for(int i = 0; i < cache.length; i++)
920 cache[i] = new Long(i - 128);
921 }
922 }
923
924 /**
925 * Returns a {@code Long} instance representing the specified
926 * {@code long} value.
927 * If a new {@code Long} instance is not required, this method
928 * should generally be used in preference to the constructor
929 * {@link #Long(long)}, as this method is likely to yield
930 * significantly better space and time performance by caching
931 * frequently requested values.
932 *
933 * Note that unlike the {@linkplain Integer#valueOf(int)
934 * corresponding method} in the {@code Integer} class, this method
935 * is <em>not</em> required to cache values within a particular
936 * range.
937 *
938 * @param l a long value.
939 * @return a {@code Long} instance representing {@code l}.
940 * @since 1.5
941 */
942 public static Long valueOf(long l) {
943 final int offset = 128;
944 if (l >= -128 && l <= 127) { // will cache
945 return LongCache.cache[(int)l + offset];
946 }
947 return new Long(l);
948 }
949
950 /**
951 * Decodes a {@code String} into a {@code Long}.
952 * Accepts decimal, hexadecimal, and octal numbers given by the
953 * following grammar:
954 *
955 * <blockquote>
956 * <dl>
957 * <dt><i>DecodableString:</i>
958 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
959 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
960 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
961 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
962 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
963 *
964 * <dt><i>Sign:</i>
965 * <dd>{@code -}
966 * <dd>{@code +}
967 * </dl>
968 * </blockquote>
969 *
970 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
971 * are as defined in section 3.10.1 of
972 * <cite>The Java™ Language Specification</cite>,
973 * except that underscores are not accepted between digits.
974 *
975 * <p>The sequence of characters following an optional
976 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
977 * "{@code #}", or leading zero) is parsed as by the {@code
978 * Long.parseLong} method with the indicated radix (10, 16, or 8).
979 * This sequence of characters must represent a positive value or
980 * a {@link NumberFormatException} will be thrown. The result is
981 * negated if first character of the specified {@code String} is
982 * the minus sign. No whitespace characters are permitted in the
983 * {@code String}.
984 *
985 * @param nm the {@code String} to decode.
986 * @return a {@code Long} object holding the {@code long}
987 * value represented by {@code nm}
988 * @throws NumberFormatException if the {@code String} does not
989 * contain a parsable {@code long}.
990 * @see java.lang.Long#parseLong(String, int)
991 * @since 1.2
992 */
993 public static Long decode(String nm) throws NumberFormatException {
994 int radix = 10;
995 int index = 0;
996 boolean negative = false;
997 Long result;
998
999 if (nm.length() == 0)
1000 throw new NumberFormatException("Zero length string");
1001 char firstChar = nm.charAt(0);
1002 // Handle sign, if present
1003 if (firstChar == '-') {
1004 negative = true;
1005 index++;
1006 } else if (firstChar == '+')
1007 index++;
1008
1009 // Handle radix specifier, if present
1010 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1011 index += 2;
1012 radix = 16;
1013 }
1014 else if (nm.startsWith("#", index)) {
1015 index ++;
1016 radix = 16;
1017 }
1018 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1019 index ++;
1020 radix = 8;
1021 }
1022
1023 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1024 throw new NumberFormatException("Sign character in wrong position");
1025
1026 try {
1027 result = Long.valueOf(nm.substring(index), radix);
1028 result = negative ? Long.valueOf(-result.longValue()) : result;
1029 } catch (NumberFormatException e) {
1030 // If number is Long.MIN_VALUE, we'll end up here. The next line
1031 // handles this case, and causes any genuine format error to be
1032 // rethrown.
1033 String constant = negative ? ("-" + nm.substring(index))
1034 : nm.substring(index);
1035 result = Long.valueOf(constant, radix);
1036 }
1037 return result;
1038 }
1039
1040 /**
1041 * The value of the {@code Long}.
1042 *
1043 * @serial
1044 */
1045 private final long value;
1046
1047 /**
1048 * Constructs a newly allocated {@code Long} object that
1049 * represents the specified {@code long} argument.
1050 *
1051 * @param value the value to be represented by the
1052 * {@code Long} object.
1053 */
1054 public Long(long value) {
1055 this.value = value;
1056 }
1057
1058 /**
1059 * Constructs a newly allocated {@code Long} object that
1060 * represents the {@code long} value indicated by the
1061 * {@code String} parameter. The string is converted to a
1062 * {@code long} value in exactly the manner used by the
1063 * {@code parseLong} method for radix 10.
1064 *
1065 * @param s the {@code String} to be converted to a
1066 * {@code Long}.
1067 * @throws NumberFormatException if the {@code String} does not
1068 * contain a parsable {@code long}.
1069 * @see java.lang.Long#parseLong(java.lang.String, int)
1070 */
1071 public Long(String s) throws NumberFormatException {
1072 this.value = parseLong(s, 10);
1073 }
1074
1075 /**
1076 * Returns the value of this {@code Long} as a {@code byte} after
1077 * a narrowing primitive conversion.
1078 * @jls 5.1.3 Narrowing Primitive Conversions
1079 */
1080 public byte byteValue() {
1081 return (byte)value;
1082 }
1083
1084 /**
1085 * Returns the value of this {@code Long} as a {@code short} after
1086 * a narrowing primitive conversion.
1087 * @jls 5.1.3 Narrowing Primitive Conversions
1088 */
1089 public short shortValue() {
1090 return (short)value;
1091 }
1092
1093 /**
1094 * Returns the value of this {@code Long} as an {@code int} after
1095 * a narrowing primitive conversion.
1096 * @jls 5.1.3 Narrowing Primitive Conversions
1097 */
1098 public int intValue() {
1099 return (int)value;
1100 }
1101
1102 /**
1103 * Returns the value of this {@code Long} as a
1104 * {@code long} value.
1105 */
1106 public long longValue() {
1107 return value;
1108 }
1109
1110 /**
1111 * Returns the value of this {@code Long} as a {@code float} after
1112 * a widening primitive conversion.
1113 * @jls 5.1.2 Widening Primitive Conversions
1114 */
1115 public float floatValue() {
1116 return (float)value;
1117 }
1118
1119 /**
1120 * Returns the value of this {@code Long} as a {@code double}
1121 * after a widening primitive conversion.
1122 * @jls 5.1.2 Widening Primitive Conversions
1123 */
1124 public double doubleValue() {
1125 return (double)value;
1126 }
1127
1128 /**
1129 * Returns a {@code String} object representing this
1130 * {@code Long}'s value. The value is converted to signed
1131 * decimal representation and returned as a string, exactly as if
1132 * the {@code long} value were given as an argument to the
1133 * {@link java.lang.Long#toString(long)} method.
1134 *
1135 * @return a string representation of the value of this object in
1136 * base 10.
1137 */
1138 public String toString() {
1139 return toString(value);
1140 }
1141
1142 /**
1143 * Returns a hash code for this {@code Long}. The result is
1144 * the exclusive OR of the two halves of the primitive
1145 * {@code long} value held by this {@code Long}
1146 * object. That is, the hashcode is the value of the expression:
1147 *
1148 * <blockquote>
1149 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1150 * </blockquote>
1151 *
1152 * @return a hash code value for this object.
1153 */
1154 @Override
1155 public int hashCode() {
1156 return Long.hashCode(value);
1157 }
1158
1159 /**
1160 * Returns a hash code for a {@code long} value; compatible with
1161 * {@code Long.hashCode()}.
1162 *
1163 * @param value the value to hash
1164 * @return a hash code value for a {@code long} value.
1165 * @since 1.8
1166 */
1167 public static int hashCode(long value) {
1168 return (int)(value ^ (value >>> 32));
1169 }
1170
1171 /**
1172 * Compares this object to the specified object. The result is
1173 * {@code true} if and only if the argument is not
1174 * {@code null} and is a {@code Long} object that
1175 * contains the same {@code long} value as this object.
1176 *
1177 * @param obj the object to compare with.
1178 * @return {@code true} if the objects are the same;
1179 * {@code false} otherwise.
1180 */
1181 public boolean equals(Object obj) {
1182 if (obj instanceof Long) {
1183 return value == ((Long)obj).longValue();
1184 }
1185 return false;
1186 }
1187
1188 /**
1189 * Determines the {@code long} value of the system property
1190 * with the specified name.
1191 *
1192 * <p>The first argument is treated as the name of a system
1193 * property. System properties are accessible through the {@link
1194 * java.lang.System#getProperty(java.lang.String)} method. The
1195 * string value of this property is then interpreted as a {@code
1196 * long} value using the grammar supported by {@link Long#decode decode}
1197 * and a {@code Long} object representing this value is returned.
1198 *
1199 * <p>If there is no property with the specified name, if the
1200 * specified name is empty or {@code null}, or if the property
1201 * does not have the correct numeric format, then {@code null} is
1202 * returned.
1203 *
1204 * <p>In other words, this method returns a {@code Long} object
1205 * equal to the value of:
1206 *
1207 * <blockquote>
1208 * {@code getLong(nm, null)}
1209 * </blockquote>
1210 *
1211 * @param nm property name.
1212 * @return the {@code Long} value of the property.
1213 * @throws SecurityException for the same reasons as
1214 * {@link System#getProperty(String) System.getProperty}
1215 * @see java.lang.System#getProperty(java.lang.String)
1216 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1217 */
1218 public static Long getLong(String nm) {
1219 return getLong(nm, null);
1220 }
1221
1222 /**
1223 * Determines the {@code long} value of the system property
1224 * with the specified name.
1225 *
1226 * <p>The first argument is treated as the name of a system
1227 * property. System properties are accessible through the {@link
1228 * java.lang.System#getProperty(java.lang.String)} method. The
1229 * string value of this property is then interpreted as a {@code
1230 * long} value using the grammar supported by {@link Long#decode decode}
1231 * and a {@code Long} object representing this value is returned.
1232 *
1233 * <p>The second argument is the default value. A {@code Long} object
1234 * that represents the value of the second argument is returned if there
1235 * is no property of the specified name, if the property does not have
1236 * the correct numeric format, or if the specified name is empty or null.
1237 *
1238 * <p>In other words, this method returns a {@code Long} object equal
1239 * to the value of:
1240 *
1241 * <blockquote>
1242 * {@code getLong(nm, new Long(val))}
1243 * </blockquote>
1244 *
1245 * but in practice it may be implemented in a manner such as:
1246 *
1247 * <blockquote><pre>
1248 * Long result = getLong(nm, null);
1249 * return (result == null) ? new Long(val) : result;
1250 * </pre></blockquote>
1251 *
1252 * to avoid the unnecessary allocation of a {@code Long} object when
1253 * the default value is not needed.
1254 *
1255 * @param nm property name.
1256 * @param val default value.
1257 * @return the {@code Long} value of the property.
1258 * @throws SecurityException for the same reasons as
1259 * {@link System#getProperty(String) System.getProperty}
1260 * @see java.lang.System#getProperty(java.lang.String)
1261 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1262 */
1263 public static Long getLong(String nm, long val) {
1264 Long result = Long.getLong(nm, null);
1265 return (result == null) ? Long.valueOf(val) : result;
1266 }
1267
1268 /**
1269 * Returns the {@code long} value of the system property with
1270 * the specified name. The first argument is treated as the name
1271 * of a system property. System properties are accessible through
1272 * the {@link java.lang.System#getProperty(java.lang.String)}
1273 * method. The string value of this property is then interpreted
1274 * as a {@code long} value, as per the
1275 * {@link Long#decode decode} method, and a {@code Long} object
1276 * representing this value is returned; in summary:
1277 *
1278 * <ul>
1279 * <li>If the property value begins with the two ASCII characters
1280 * {@code 0x} or the ASCII character {@code #}, not followed by
1281 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1282 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1283 * with radix 16.
1284 * <li>If the property value begins with the ASCII character
1285 * {@code 0} followed by another character, it is parsed as
1286 * an octal integer exactly as by the method {@link
1287 * #valueOf(java.lang.String, int)} with radix 8.
1288 * <li>Otherwise the property value is parsed as a decimal
1289 * integer exactly as by the method
1290 * {@link #valueOf(java.lang.String, int)} with radix 10.
1291 * </ul>
1292 *
1293 * <p>Note that, in every case, neither {@code L}
1294 * ({@code '\u005Cu004C'}) nor {@code l}
1295 * ({@code '\u005Cu006C'}) is permitted to appear at the end
1296 * of the property value as a type indicator, as would be
1297 * permitted in Java programming language source code.
1298 *
1299 * <p>The second argument is the default value. The default value is
1300 * returned if there is no property of the specified name, if the
1301 * property does not have the correct numeric format, or if the
1302 * specified name is empty or {@code null}.
1303 *
1304 * @param nm property name.
1305 * @param val default value.
1306 * @return the {@code Long} value of the property.
1307 * @throws SecurityException for the same reasons as
1308 * {@link System#getProperty(String) System.getProperty}
1309 * @see System#getProperty(java.lang.String)
1310 * @see System#getProperty(java.lang.String, java.lang.String)
1311 */
1312 public static Long getLong(String nm, Long val) {
1313 String v = null;
1314 try {
1315 v = System.getProperty(nm);
1316 } catch (IllegalArgumentException | NullPointerException e) {
1317 }
1318 if (v != null) {
1319 try {
1320 return Long.decode(v);
1321 } catch (NumberFormatException e) {
1322 }
1323 }
1324 return val;
1325 }
1326
1327 /**
1328 * Compares two {@code Long} objects numerically.
1329 *
1330 * @param anotherLong the {@code Long} to be compared.
1331 * @return the value {@code 0} if this {@code Long} is
1332 * equal to the argument {@code Long}; a value less than
1333 * {@code 0} if this {@code Long} is numerically less
1334 * than the argument {@code Long}; and a value greater
1335 * than {@code 0} if this {@code Long} is numerically
1336 * greater than the argument {@code Long} (signed
1337 * comparison).
1338 * @since 1.2
1339 */
1340 public int compareTo(Long anotherLong) {
1341 return compare(this.value, anotherLong.value);
1342 }
1343
1344 /**
1345 * Compares two {@code long} values numerically.
1346 * The value returned is identical to what would be returned by:
1347 * <pre>
1348 * Long.valueOf(x).compareTo(Long.valueOf(y))
1349 * </pre>
1350 *
1351 * @param x the first {@code long} to compare
1352 * @param y the second {@code long} to compare
1353 * @return the value {@code 0} if {@code x == y};
1354 * a value less than {@code 0} if {@code x < y}; and
1355 * a value greater than {@code 0} if {@code x > y}
1356 * @since 1.7
1357 */
1358 public static int compare(long x, long y) {
1359 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1360 }
1361
1362 /**
1363 * Compares two {@code long} values numerically treating the values
1364 * as unsigned.
1365 *
1366 * @param x the first {@code long} to compare
1367 * @param y the second {@code long} to compare
1368 * @return the value {@code 0} if {@code x == y}; a value less
1369 * than {@code 0} if {@code x < y} as unsigned values; and
1370 * a value greater than {@code 0} if {@code x > y} as
1371 * unsigned values
1372 * @since 1.8
1373 */
1374 public static int compareUnsigned(long x, long y) {
1375 return compare(x + MIN_VALUE, y + MIN_VALUE);
1376 }
1377
1378
1379 /**
1380 * Returns the unsigned quotient of dividing the first argument by
1381 * the second where each argument and the result is interpreted as
1382 * an unsigned value.
1383 *
1384 * <p>Note that in two's complement arithmetic, the three other
1385 * basic arithmetic operations of add, subtract, and multiply are
1386 * bit-wise identical if the two operands are regarded as both
1387 * being signed or both being unsigned. Therefore separate {@code
1388 * addUnsigned}, etc. methods are not provided.
1389 *
1390 * @param dividend the value to be divided
1391 * @param divisor the value doing the dividing
1392 * @return the unsigned quotient of the first argument divided by
1393 * the second argument
1394 * @see #remainderUnsigned
1395 * @since 1.8
1396 */
1397 public static long divideUnsigned(long dividend, long divisor) {
1398 if (divisor < 0L) { // signed comparison
1399 // Answer must be 0 or 1 depending on relative magnitude
1400 // of dividend and divisor.
1401 return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;
1402 }
1403
1404 if (dividend > 0) // Both inputs non-negative
1405 return dividend/divisor;
1406 else {
1407 /*
1408 * For simple code, leveraging BigInteger. Longer and faster
1409 * code written directly in terms of operations on longs is
1410 * possible; see "Hacker's Delight" for divide and remainder
1411 * algorithms.
1412 */
1413 return toUnsignedBigInteger(dividend).
1414 divide(toUnsignedBigInteger(divisor)).longValue();
1415 }
1416 }
1417
1418 /**
1419 * Returns the unsigned remainder from dividing the first argument
1420 * by the second where each argument and the result is interpreted
1421 * as an unsigned value.
1422 *
1423 * @param dividend the value to be divided
1424 * @param divisor the value doing the dividing
1425 * @return the unsigned remainder of the first argument divided by
1426 * the second argument
1427 * @see #divideUnsigned
1428 * @since 1.8
1429 */
1430 public static long remainderUnsigned(long dividend, long divisor) {
1431 if (dividend > 0 && divisor > 0) { // signed comparisons
1432 return dividend % divisor;
1433 } else {
1434 if (compareUnsigned(dividend, divisor) < 0) // Avoid explicit check for 0 divisor
1435 return dividend;
1436 else
1437 return toUnsignedBigInteger(dividend).
1438 remainder(toUnsignedBigInteger(divisor)).longValue();
1439 }
1440 }
1441
1442 // Bit Twiddling
1443
1444 /**
1445 * The number of bits used to represent a {@code long} value in two's
1446 * complement binary form.
1447 *
1448 * @since 1.5
1449 */
1450 @Native public static final int SIZE = 64;
1451
1452 /**
1453 * The number of bytes used to represent a {@code long} value in two's
1454 * complement binary form.
1455 *
1456 * @since 1.8
1457 */
1458 public static final int BYTES = SIZE / Byte.SIZE;
1459
1460 /**
1461 * Returns a {@code long} value with at most a single one-bit, in the
1462 * position of the highest-order ("leftmost") one-bit in the specified
1463 * {@code long} value. Returns zero if the specified value has no
1464 * one-bits in its two's complement binary representation, that is, if it
1465 * is equal to zero.
1466 *
1467 * @param i the value whose highest one bit is to be computed
1468 * @return a {@code long} value with a single one-bit, in the position
1469 * of the highest-order one-bit in the specified value, or zero if
1470 * the specified value is itself equal to zero.
1471 * @since 1.5
1472 */
1473 public static long highestOneBit(long i) {
1474 // HD, Figure 3-1
1475 i |= (i >> 1);
1476 i |= (i >> 2);
1477 i |= (i >> 4);
1478 i |= (i >> 8);
1479 i |= (i >> 16);
1480 i |= (i >> 32);
1481 return i - (i >>> 1);
1482 }
1483
1484 /**
1485 * Returns a {@code long} value with at most a single one-bit, in the
1486 * position of the lowest-order ("rightmost") one-bit in the specified
1487 * {@code long} value. Returns zero if the specified value has no
1488 * one-bits in its two's complement binary representation, that is, if it
1489 * is equal to zero.
1490 *
1491 * @param i the value whose lowest one bit is to be computed
1492 * @return a {@code long} value with a single one-bit, in the position
1493 * of the lowest-order one-bit in the specified value, or zero if
1494 * the specified value is itself equal to zero.
1495 * @since 1.5
1496 */
1497 public static long lowestOneBit(long i) {
1498 // HD, Section 2-1
1499 return i & -i;
1500 }
1501
1502 /**
1503 * Returns the number of zero bits preceding the highest-order
1504 * ("leftmost") one-bit in the two's complement binary representation
1505 * of the specified {@code long} value. Returns 64 if the
1506 * specified value has no one-bits in its two's complement representation,
1507 * in other words if it is equal to zero.
1508 *
1509 * <p>Note that this method is closely related to the logarithm base 2.
1510 * For all positive {@code long} values x:
1511 * <ul>
1512 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1513 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1514 * </ul>
1515 *
1516 * @param i the value whose number of leading zeros is to be computed
1517 * @return the number of zero bits preceding the highest-order
1518 * ("leftmost") one-bit in the two's complement binary representation
1519 * of the specified {@code long} value, or 64 if the value
1520 * is equal to zero.
1521 * @since 1.5
1522 */
1523 public static int numberOfLeadingZeros(long i) {
1524 // HD, Figure 5-6
1525 if (i == 0)
1526 return 64;
1527 int n = 1;
1528 int x = (int)(i >>> 32);
1529 if (x == 0) { n += 32; x = (int)i; }
1530 if (x >>> 16 == 0) { n += 16; x <<= 16; }
1531 if (x >>> 24 == 0) { n += 8; x <<= 8; }
1532 if (x >>> 28 == 0) { n += 4; x <<= 4; }
1533 if (x >>> 30 == 0) { n += 2; x <<= 2; }
1534 n -= x >>> 31;
1535 return n;
1536 }
1537
1538 /**
1539 * Returns the number of zero bits following the lowest-order ("rightmost")
1540 * one-bit in the two's complement binary representation of the specified
1541 * {@code long} value. Returns 64 if the specified value has no
1542 * one-bits in its two's complement representation, in other words if it is
1543 * equal to zero.
1544 *
1545 * @param i the value whose number of trailing zeros is to be computed
1546 * @return the number of zero bits following the lowest-order ("rightmost")
1547 * one-bit in the two's complement binary representation of the
1548 * specified {@code long} value, or 64 if the value is equal
1549 * to zero.
1550 * @since 1.5
1551 */
1552 public static int numberOfTrailingZeros(long i) {
1553 // HD, Figure 5-14
1554 int x, y;
1555 if (i == 0) return 64;
1556 int n = 63;
1557 y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
1558 y = x <<16; if (y != 0) { n = n -16; x = y; }
1559 y = x << 8; if (y != 0) { n = n - 8; x = y; }
1560 y = x << 4; if (y != 0) { n = n - 4; x = y; }
1561 y = x << 2; if (y != 0) { n = n - 2; x = y; }
1562 return n - ((x << 1) >>> 31);
1563 }
1564
1565 /**
1566 * Returns the number of one-bits in the two's complement binary
1567 * representation of the specified {@code long} value. This function is
1568 * sometimes referred to as the <i>population count</i>.
1569 *
1570 * @param i the value whose bits are to be counted
1571 * @return the number of one-bits in the two's complement binary
1572 * representation of the specified {@code long} value.
1573 * @since 1.5
1574 */
1575 public static int bitCount(long i) {
1576 // HD, Figure 5-14
1577 i = i - ((i >>> 1) & 0x5555555555555555L);
1578 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1579 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1580 i = i + (i >>> 8);
1581 i = i + (i >>> 16);
1582 i = i + (i >>> 32);
1583 return (int)i & 0x7f;
1584 }
1585
1586 /**
1587 * Returns the value obtained by rotating the two's complement binary
1588 * representation of the specified {@code long} value left by the
1589 * specified number of bits. (Bits shifted out of the left hand, or
1590 * high-order, side reenter on the right, or low-order.)
1591 *
1592 * <p>Note that left rotation with a negative distance is equivalent to
1593 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1594 * distance)}. Note also that rotation by any multiple of 64 is a
1595 * no-op, so all but the last six bits of the rotation distance can be
1596 * ignored, even if the distance is negative: {@code rotateLeft(val,
1597 * distance) == rotateLeft(val, distance & 0x3F)}.
1598 *
1599 * @param i the value whose bits are to be rotated left
1600 * @param distance the number of bit positions to rotate left
1601 * @return the value obtained by rotating the two's complement binary
1602 * representation of the specified {@code long} value left by the
1603 * specified number of bits.
1604 * @since 1.5
1605 */
1606 public static long rotateLeft(long i, int distance) {
1607 return (i << distance) | (i >>> -distance);
1608 }
1609
1610 /**
1611 * Returns the value obtained by rotating the two's complement binary
1612 * representation of the specified {@code long} value right by the
1613 * specified number of bits. (Bits shifted out of the right hand, or
1614 * low-order, side reenter on the left, or high-order.)
1615 *
1616 * <p>Note that right rotation with a negative distance is equivalent to
1617 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1618 * distance)}. Note also that rotation by any multiple of 64 is a
1619 * no-op, so all but the last six bits of the rotation distance can be
1620 * ignored, even if the distance is negative: {@code rotateRight(val,
1621 * distance) == rotateRight(val, distance & 0x3F)}.
1622 *
1623 * @param i the value whose bits are to be rotated right
1624 * @param distance the number of bit positions to rotate right
1625 * @return the value obtained by rotating the two's complement binary
1626 * representation of the specified {@code long} value right by the
1627 * specified number of bits.
1628 * @since 1.5
1629 */
1630 public static long rotateRight(long i, int distance) {
1631 return (i >>> distance) | (i << -distance);
1632 }
1633
1634 /**
1635 * Returns the value obtained by reversing the order of the bits in the
1636 * two's complement binary representation of the specified {@code long}
1637 * value.
1638 *
1639 * @param i the value to be reversed
1640 * @return the value obtained by reversing order of the bits in the
1641 * specified {@code long} value.
1642 * @since 1.5
1643 */
1644 public static long reverse(long i) {
1645 // HD, Figure 7-1
1646 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1647 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1648 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1649 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1650 i = (i << 48) | ((i & 0xffff0000L) << 16) |
1651 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1652 return i;
1653 }
1654
1655 /**
1656 * Returns the signum function of the specified {@code long} value. (The
1657 * return value is -1 if the specified value is negative; 0 if the
1658 * specified value is zero; and 1 if the specified value is positive.)
1659 *
1660 * @param i the value whose signum is to be computed
1661 * @return the signum function of the specified {@code long} value.
1662 * @since 1.5
1663 */
1664 public static int signum(long i) {
1665 // HD, Section 2-7
1666 return (int) ((i >> 63) | (-i >>> 63));
1667 }
1668
1669 /**
1670 * Returns the value obtained by reversing the order of the bytes in the
1671 * two's complement representation of the specified {@code long} value.
1672 *
1673 * @param i the value whose bytes are to be reversed
1674 * @return the value obtained by reversing the bytes in the specified
1675 * {@code long} value.
1676 * @since 1.5
1677 */
1678 public static long reverseBytes(long i) {
1679 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1680 return (i << 48) | ((i & 0xffff0000L) << 16) |
1681 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1682 }
1683
1684 /**
1685 * Adds two {@code long} values together as per the + operator.
1686 *
1687 * @param a the first operand
1688 * @param b the second operand
1689 * @return the sum of {@code a} and {@code b}
1690 * @see java.util.function.BinaryOperator
1691 * @since 1.8
1692 */
1693 public static long sum(long a, long b) {
1694 return a + b;
1695 }
1696
1697 /**
1698 * Returns the greater of two {@code long} values
1699 * as if by calling {@link Math#max(long, long) Math.max}.
1700 *
1701 * @param a the first operand
1702 * @param b the second operand
1703 * @return the greater of {@code a} and {@code b}
1704 * @see java.util.function.BinaryOperator
1705 * @since 1.8
1706 */
1707 public static long max(long a, long b) {
1708 return Math.max(a, b);
1709 }
1710
1711 /**
1712 * Returns the smaller of two {@code long} values
1713 * as if by calling {@link Math#min(long, long) Math.min}.
1714 *
1715 * @param a the first operand
1716 * @param b the second operand
1717 * @return the smaller of {@code a} and {@code b}
1718 * @see java.util.function.BinaryOperator
1719 * @since 1.8
1720 */
1721 public static long min(long a, long b) {
1722 return Math.min(a, b);
1723 }
1724
1725 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1726 @Native private static final long serialVersionUID = 4290774380558885855L;
1727 }