1 /*
2 * Copyright (c) 1994, 2018, 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.lang.invoke.MethodHandles;
30 import java.lang.constant.Constable;
31 import java.lang.constant.ConstantDesc;
32 import java.math.*;
33 import java.util.Objects;
34 import java.util.Optional;
35
36 import jdk.internal.HotSpotIntrinsicCandidate;
37 import jdk.internal.misc.VM;
38
39 import static java.lang.String.COMPACT_STRINGS;
40 import static java.lang.String.LATIN1;
41 import static java.lang.String.UTF16;
42
43 /**
44 * The {@code Long} class wraps a value of the primitive type {@code
45 * long} in an object. An object of type {@code Long} contains a
46 * single field whose type is {@code long}.
47 *
48 * <p> In addition, this class provides several methods for converting
49 * a {@code long} to a {@code String} and a {@code String} to a {@code
50 * long}, as well as other constants and methods useful when dealing
51 * with a {@code long}.
52 *
53 * <p>Implementation note: The implementations of the "bit twiddling"
54 * methods (such as {@link #highestOneBit(long) highestOneBit} and
55 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
56 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
57 * Delight</i>, (Addison Wesley, 2002).
58 *
59 * @author Lee Boynton
60 * @author Arthur van Hoff
61 * @author Josh Bloch
62 * @author Joseph D. Darcy
63 * @since 1.0
64 */
65 public final class Long extends Number
66 implements Comparable<Long>, Constable, ConstantDesc {
67 /**
68 * A constant holding the minimum value a {@code long} can
69 * have, -2<sup>63</sup>.
70 */
71 @Native public static final long MIN_VALUE = 0x8000000000000000L;
72
73 /**
74 * A constant holding the maximum value a {@code long} can
75 * have, 2<sup>63</sup>-1.
76 */
77 @Native public static final long MAX_VALUE = 0x7fffffffffffffffL;
78
79 /**
80 * The {@code Class} instance representing the primitive type
81 * {@code long}.
82 *
83 * @since 1.1
84 */
85 @SuppressWarnings("unchecked")
86 public static final Class<Long> TYPE = (Class<Long>) Class.getPrimitiveClass("long");
87
88 /**
89 * Returns a string representation of the first argument in the
90 * radix specified by the second argument.
91 *
92 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
93 * or larger than {@code Character.MAX_RADIX}, then the radix
94 * {@code 10} is used instead.
95 *
96 * <p>If the first argument is negative, the first element of the
97 * result is the ASCII minus sign {@code '-'}
98 * ({@code '\u005Cu002d'}). If the first argument is not
99 * negative, no sign character appears in the result.
100 *
101 * <p>The remaining characters of the result represent the magnitude
102 * of the first argument. If the magnitude is zero, it is
103 * represented by a single zero character {@code '0'}
104 * ({@code '\u005Cu0030'}); otherwise, the first character of
105 * the representation of the magnitude will not be the zero
106 * character. The following ASCII characters are used as digits:
107 *
108 * <blockquote>
109 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
110 * </blockquote>
111 *
112 * These are {@code '\u005Cu0030'} through
113 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
114 * {@code '\u005Cu007a'}. If {@code radix} is
115 * <var>N</var>, then the first <var>N</var> of these characters
116 * are used as radix-<var>N</var> digits in the order shown. Thus,
117 * the digits for hexadecimal (radix 16) are
118 * {@code 0123456789abcdef}. If uppercase letters are
119 * desired, the {@link java.lang.String#toUpperCase()} method may
120 * be called on the result:
121 *
122 * <blockquote>
123 * {@code Long.toString(n, 16).toUpperCase()}
124 * </blockquote>
125 *
126 * @param i a {@code long} to be converted to a string.
127 * @param radix the radix to use in the string representation.
128 * @return a string representation of the argument in the specified radix.
129 * @see java.lang.Character#MAX_RADIX
130 * @see java.lang.Character#MIN_RADIX
131 */
132 public static String toString(long i, int radix) {
133 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
134 radix = 10;
135 if (radix == 10)
136 return toString(i);
137
138 if (COMPACT_STRINGS) {
139 byte[] buf = new byte[65];
140 int charPos = 64;
141 boolean negative = (i < 0);
142
143 if (!negative) {
144 i = -i;
145 }
146
147 while (i <= -radix) {
148 buf[charPos--] = (byte)Integer.digits[(int)(-(i % radix))];
149 i = i / radix;
150 }
151 buf[charPos] = (byte)Integer.digits[(int)(-i)];
152
153 if (negative) {
154 buf[--charPos] = '-';
155 }
156 return StringLatin1.newString(buf, charPos, (65 - charPos));
157 }
158 return toStringUTF16(i, radix);
159 }
160
161 private static String toStringUTF16(long i, int radix) {
162 byte[] buf = new byte[65 * 2];
163 int charPos = 64;
164 boolean negative = (i < 0);
165 if (!negative) {
166 i = -i;
167 }
168 while (i <= -radix) {
169 StringUTF16.putChar(buf, charPos--, Integer.digits[(int)(-(i % radix))]);
170 i = i / radix;
171 }
172 StringUTF16.putChar(buf, charPos, Integer.digits[(int)(-i)]);
173 if (negative) {
174 StringUTF16.putChar(buf, --charPos, '-');
175 }
176 return StringUTF16.newString(buf, charPos, (65 - charPos));
177 }
178
179 /**
180 * Returns a string representation of the first argument as an
181 * unsigned integer value in the radix specified by the second
182 * argument.
183 *
184 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
185 * or larger than {@code Character.MAX_RADIX}, then the radix
186 * {@code 10} is used instead.
187 *
188 * <p>Note that since the first argument is treated as an unsigned
189 * value, no leading sign character is printed.
190 *
191 * <p>If the magnitude is zero, it is represented by a single zero
192 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
193 * the first character of the representation of the magnitude will
194 * not be the zero character.
195 *
196 * <p>The behavior of radixes and the characters used as digits
197 * are the same as {@link #toString(long, int) toString}.
198 *
199 * @param i an integer to be converted to an unsigned string.
200 * @param radix the radix to use in the string representation.
201 * @return an unsigned string representation of the argument in the specified radix.
202 * @see #toString(long, int)
203 * @since 1.8
204 */
205 public static String toUnsignedString(long i, int radix) {
206 if (i >= 0)
207 return toString(i, radix);
208 else {
209 switch (radix) {
210 case 2:
211 return toBinaryString(i);
212
213 case 4:
214 return toUnsignedString0(i, 2);
215
216 case 8:
217 return toOctalString(i);
218
219 case 10:
220 /*
221 * We can get the effect of an unsigned division by 10
222 * on a long value by first shifting right, yielding a
223 * positive value, and then dividing by 5. This
224 * allows the last digit and preceding digits to be
225 * isolated more quickly than by an initial conversion
226 * to BigInteger.
227 */
228 long quot = (i >>> 1) / 5;
229 long rem = i - quot * 10;
230 return toString(quot) + rem;
231
232 case 16:
233 return toHexString(i);
234
235 case 32:
236 return toUnsignedString0(i, 5);
237
238 default:
239 return toUnsignedBigInteger(i).toString(radix);
240 }
241 }
242 }
243
244 /**
245 * Return a BigInteger equal to the unsigned value of the
246 * argument.
247 */
248 private static BigInteger toUnsignedBigInteger(long i) {
249 if (i >= 0L)
250 return BigInteger.valueOf(i);
251 else {
252 int upper = (int) (i >>> 32);
253 int lower = (int) i;
254
255 // return (upper << 32) + lower
256 return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
257 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
258 }
259 }
260
261 /**
262 * Returns a string representation of the {@code long}
263 * argument as an unsigned integer in base 16.
264 *
265 * <p>The unsigned {@code long} value is the argument plus
266 * 2<sup>64</sup> if the argument is negative; otherwise, it is
267 * equal to the argument. This value is converted to a string of
268 * ASCII digits in hexadecimal (base 16) with no extra
269 * leading {@code 0}s.
270 *
271 * <p>The value of the argument can be recovered from the returned
272 * string {@code s} by calling {@link
273 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
274 * 16)}.
275 *
276 * <p>If the unsigned magnitude is zero, it is represented by a
277 * single zero character {@code '0'} ({@code '\u005Cu0030'});
278 * otherwise, the first character of the representation of the
279 * unsigned magnitude will not be the zero character. The
280 * following characters are used as hexadecimal digits:
281 *
282 * <blockquote>
283 * {@code 0123456789abcdef}
284 * </blockquote>
285 *
286 * These are the characters {@code '\u005Cu0030'} through
287 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
288 * {@code '\u005Cu0066'}. If uppercase letters are desired,
289 * the {@link java.lang.String#toUpperCase()} method may be called
290 * on the result:
291 *
292 * <blockquote>
293 * {@code Long.toHexString(n).toUpperCase()}
294 * </blockquote>
295 *
296 * @param i a {@code long} to be converted to a string.
297 * @return the string representation of the unsigned {@code long}
298 * value represented by the argument in hexadecimal
299 * (base 16).
300 * @see #parseUnsignedLong(String, int)
301 * @see #toUnsignedString(long, int)
302 * @since 1.0.2
303 */
304 public static String toHexString(long i) {
305 return toUnsignedString0(i, 4);
306 }
307
308 /**
309 * Returns a string representation of the {@code long}
310 * argument as an unsigned integer in base 8.
311 *
312 * <p>The unsigned {@code long} value is the argument plus
313 * 2<sup>64</sup> if the argument is negative; otherwise, it is
314 * equal to the argument. This value is converted to a string of
315 * ASCII digits in octal (base 8) with no extra leading
316 * {@code 0}s.
317 *
318 * <p>The value of the argument can be recovered from the returned
319 * string {@code s} by calling {@link
320 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
321 * 8)}.
322 *
323 * <p>If the unsigned magnitude is zero, it is represented by a
324 * single zero character {@code '0'} ({@code '\u005Cu0030'});
325 * otherwise, the first character of the representation of the
326 * unsigned magnitude will not be the zero character. The
327 * following characters are used as octal digits:
328 *
329 * <blockquote>
330 * {@code 01234567}
331 * </blockquote>
332 *
333 * These are the characters {@code '\u005Cu0030'} through
334 * {@code '\u005Cu0037'}.
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 octal (base 8).
339 * @see #parseUnsignedLong(String, int)
340 * @see #toUnsignedString(long, int)
341 * @since 1.0.2
342 */
343 public static String toOctalString(long i) {
344 return toUnsignedString0(i, 3);
345 }
346
347 /**
348 * Returns a string representation of the {@code long}
349 * argument as an unsigned integer in base 2.
350 *
351 * <p>The unsigned {@code long} value is the argument plus
352 * 2<sup>64</sup> if the argument is negative; otherwise, it is
353 * equal to the argument. This value is converted to a string of
354 * ASCII digits in binary (base 2) with no extra leading
355 * {@code 0}s.
356 *
357 * <p>The value of the argument can be recovered from the returned
358 * string {@code s} by calling {@link
359 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
360 * 2)}.
361 *
362 * <p>If the unsigned magnitude is zero, it is represented by a
363 * single zero character {@code '0'} ({@code '\u005Cu0030'});
364 * otherwise, the first character of the representation of the
365 * unsigned magnitude will not be the zero character. The
366 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
367 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
368 *
369 * @param i a {@code long} to be converted to a string.
370 * @return the string representation of the unsigned {@code long}
371 * value represented by the argument in binary (base 2).
372 * @see #parseUnsignedLong(String, int)
373 * @see #toUnsignedString(long, int)
374 * @since 1.0.2
375 */
376 public static String toBinaryString(long i) {
377 return toUnsignedString0(i, 1);
378 }
379
380 /**
381 * Format a long (treated as unsigned) into a String.
382 * @param val the value to format
383 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
384 */
385 static String toUnsignedString0(long val, int shift) {
386 // assert shift > 0 && shift <=5 : "Illegal shift value";
387 int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
388 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
389 if (COMPACT_STRINGS) {
390 byte[] buf = new byte[chars];
391 formatUnsignedLong0(val, shift, buf, 0, chars);
392 return new String(buf, LATIN1);
393 } else {
394 byte[] buf = new byte[chars * 2];
395 formatUnsignedLong0UTF16(val, shift, buf, 0, chars);
396 return new String(buf, UTF16);
397 }
398 }
399
400 /**
401 * Format a long (treated as unsigned) into a character buffer. If
402 * {@code len} exceeds the formatted ASCII representation of {@code val},
403 * {@code buf} will be padded with leading zeroes.
404 *
405 * @param val the unsigned long to format
406 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
407 * @param buf the character buffer to write to
408 * @param offset the offset in the destination buffer to start at
409 * @param len the number of characters to write
410 */
411
412 /** byte[]/LATIN1 version */
413 static void formatUnsignedLong0(long val, int shift, byte[] buf, int offset, int len) {
414 int charPos = offset + len;
415 int radix = 1 << shift;
416 int mask = radix - 1;
417 do {
418 buf[--charPos] = (byte)Integer.digits[((int) val) & mask];
419 val >>>= shift;
420 } while (charPos > offset);
421 }
422
423 /** byte[]/UTF16 version */
424 private static void formatUnsignedLong0UTF16(long val, int shift, byte[] buf, int offset, int len) {
425 int charPos = offset + len;
426 int radix = 1 << shift;
427 int mask = radix - 1;
428 do {
429 StringUTF16.putChar(buf, --charPos, Integer.digits[((int) val) & mask]);
430 val >>>= shift;
431 } while (charPos > offset);
432 }
433
434 static String fastUUID(long lsb, long msb) {
435 if (COMPACT_STRINGS) {
436 byte[] buf = new byte[36];
437 formatUnsignedLong0(lsb, 4, buf, 24, 12);
438 formatUnsignedLong0(lsb >>> 48, 4, buf, 19, 4);
439 formatUnsignedLong0(msb, 4, buf, 14, 4);
440 formatUnsignedLong0(msb >>> 16, 4, buf, 9, 4);
441 formatUnsignedLong0(msb >>> 32, 4, buf, 0, 8);
442
443 buf[23] = '-';
444 buf[18] = '-';
445 buf[13] = '-';
446 buf[8] = '-';
447
448 return new String(buf, LATIN1);
449 } else {
450 byte[] buf = new byte[72];
451
452 formatUnsignedLong0UTF16(lsb, 4, buf, 24, 12);
453 formatUnsignedLong0UTF16(lsb >>> 48, 4, buf, 19, 4);
454 formatUnsignedLong0UTF16(msb, 4, buf, 14, 4);
455 formatUnsignedLong0UTF16(msb >>> 16, 4, buf, 9, 4);
456 formatUnsignedLong0UTF16(msb >>> 32, 4, buf, 0, 8);
457
458 StringUTF16.putChar(buf, 23, '-');
459 StringUTF16.putChar(buf, 18, '-');
460 StringUTF16.putChar(buf, 13, '-');
461 StringUTF16.putChar(buf, 8, '-');
462
463 return new String(buf, UTF16);
464 }
465 }
466
467 /**
468 * Returns a {@code String} object representing the specified
469 * {@code long}. The argument is converted to signed decimal
470 * representation and returned as a string, exactly as if the
471 * argument and the radix 10 were given as arguments to the {@link
472 * #toString(long, int)} method.
473 *
474 * @param i a {@code long} to be converted.
475 * @return a string representation of the argument in base 10.
476 */
477 public static String toString(long i) {
478 int size = stringSize(i);
479 if (COMPACT_STRINGS) {
480 byte[] buf = new byte[size];
481 getChars(i, size, buf);
482 return new String(buf, LATIN1);
483 } else {
484 byte[] buf = new byte[size * 2];
485 StringUTF16.getChars(i, size, buf);
486 return new String(buf, UTF16);
487 }
488 }
489
490 /**
491 * Returns a string representation of the argument as an unsigned
492 * decimal value.
493 *
494 * The argument is converted to unsigned decimal representation
495 * and returned as a string exactly as if the argument and radix
496 * 10 were given as arguments to the {@link #toUnsignedString(long,
497 * int)} method.
498 *
499 * @param i an integer to be converted to an unsigned string.
500 * @return an unsigned string representation of the argument.
501 * @see #toUnsignedString(long, int)
502 * @since 1.8
503 */
504 public static String toUnsignedString(long i) {
505 return toUnsignedString(i, 10);
506 }
507
508 /**
509 * Places characters representing the long i into the
510 * character array buf. The characters are placed into
511 * the buffer backwards starting with the least significant
512 * digit at the specified index (exclusive), and working
513 * backwards from there.
514 *
515 * @implNote This method converts positive inputs into negative
516 * values, to cover the Long.MIN_VALUE case. Converting otherwise
517 * (negative to positive) will expose -Long.MIN_VALUE that overflows
518 * long.
519 *
520 * @param i value to convert
521 * @param index next index, after the least significant digit
522 * @param buf target buffer, Latin1-encoded
523 * @return index of the most significant digit or minus sign, if present
524 */
525 static int getChars(long i, int index, byte[] buf) {
526 long q;
527 int r;
528 int charPos = index;
529
530 boolean negative = (i < 0);
531 if (!negative) {
532 i = -i;
533 }
534
535 // Get 2 digits/iteration using longs until quotient fits into an int
536 while (i <= Integer.MIN_VALUE) {
537 q = i / 100;
538 r = (int)((q * 100) - i);
539 i = q;
540 buf[--charPos] = Integer.DigitOnes[r];
541 buf[--charPos] = Integer.DigitTens[r];
542 }
543
544 // Get 2 digits/iteration using ints
545 int q2;
546 int i2 = (int)i;
547 while (i2 <= -100) {
548 q2 = i2 / 100;
549 r = (q2 * 100) - i2;
550 i2 = q2;
551 buf[--charPos] = Integer.DigitOnes[r];
552 buf[--charPos] = Integer.DigitTens[r];
553 }
554
555 // We know there are at most two digits left at this point.
556 q2 = i2 / 10;
557 r = (q2 * 10) - i2;
558 buf[--charPos] = (byte)('0' + r);
559
560 // Whatever left is the remaining digit.
561 if (q2 < 0) {
562 buf[--charPos] = (byte)('0' - q2);
563 }
564
565 if (negative) {
566 buf[--charPos] = (byte)'-';
567 }
568 return charPos;
569 }
570
571 /**
572 * Returns the string representation size for a given long value.
573 *
574 * @param x long value
575 * @return string size
576 *
577 * @implNote There are other ways to compute this: e.g. binary search,
578 * but values are biased heavily towards zero, and therefore linear search
579 * wins. The iteration results are also routinely inlined in the generated
580 * code after loop unrolling.
581 */
582 static int stringSize(long x) {
583 int d = 1;
584 if (x >= 0) {
585 d = 0;
586 x = -x;
587 }
588 long p = -10;
589 for (int i = 1; i < 19; i++) {
590 if (x > p)
591 return i + d;
592 p = 10 * p;
593 }
594 return 19 + d;
595 }
596
597 /**
598 * Parses the string argument as a signed {@code long} in the
599 * radix specified by the second argument. The characters in the
600 * string must all be digits of the specified radix (as determined
601 * by whether {@link java.lang.Character#digit(char, int)} returns
602 * a nonnegative value), except that the first character may be an
603 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
604 * indicate a negative value or an ASCII plus sign {@code '+'}
605 * ({@code '\u005Cu002B'}) to indicate a positive value. The
606 * resulting {@code long} value is returned.
607 *
608 * <p>Note that neither the character {@code L}
609 * ({@code '\u005Cu004C'}) nor {@code l}
610 * ({@code '\u005Cu006C'}) is permitted to appear at the end
611 * of the string as a type indicator, as would be permitted in
612 * Java programming language source code - except that either
613 * {@code L} or {@code l} may appear as a digit for a
614 * radix greater than or equal to 22.
615 *
616 * <p>An exception of type {@code NumberFormatException} is
617 * thrown if any of the following situations occurs:
618 * <ul>
619 *
620 * <li>The first argument is {@code null} or is a string of
621 * length zero.
622 *
623 * <li>The {@code radix} is either smaller than {@link
624 * java.lang.Character#MIN_RADIX} or larger than {@link
625 * java.lang.Character#MAX_RADIX}.
626 *
627 * <li>Any character of the string is not a digit of the specified
628 * radix, except that the first character may be a minus sign
629 * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
630 * '+'} ({@code '\u005Cu002B'}) provided that the string is
631 * longer than length 1.
632 *
633 * <li>The value represented by the string is not a value of type
634 * {@code long}.
635 * </ul>
636 *
637 * <p>Examples:
638 * <blockquote><pre>
639 * parseLong("0", 10) returns 0L
640 * parseLong("473", 10) returns 473L
641 * parseLong("+42", 10) returns 42L
642 * parseLong("-0", 10) returns 0L
643 * parseLong("-FF", 16) returns -255L
644 * parseLong("1100110", 2) returns 102L
645 * parseLong("99", 8) throws a NumberFormatException
646 * parseLong("Hazelnut", 10) throws a NumberFormatException
647 * parseLong("Hazelnut", 36) returns 1356099454469L
648 * </pre></blockquote>
649 *
650 * @param s the {@code String} containing the
651 * {@code long} representation to be parsed.
652 * @param radix the radix to be used while parsing {@code s}.
653 * @return the {@code long} represented by the string argument in
654 * the specified radix.
655 * @throws NumberFormatException if the string does not contain a
656 * parsable {@code long}.
657 */
658 public static long parseLong(String s, int radix)
659 throws NumberFormatException
660 {
661 if (s == null) {
662 throw new NumberFormatException("null");
663 }
664
665 if (radix < Character.MIN_RADIX) {
666 throw new NumberFormatException("radix " + radix +
667 " less than Character.MIN_RADIX");
668 }
669 if (radix > Character.MAX_RADIX) {
670 throw new NumberFormatException("radix " + radix +
671 " greater than Character.MAX_RADIX");
672 }
673
674 boolean negative = false;
675 int i = 0, len = s.length();
676 long limit = -Long.MAX_VALUE;
677
678 if (len > 0) {
679 char firstChar = s.charAt(0);
680 if (firstChar < '0') { // Possible leading "+" or "-"
681 if (firstChar == '-') {
682 negative = true;
683 limit = Long.MIN_VALUE;
684 } else if (firstChar != '+') {
685 throw NumberFormatException.forInputString(s, radix);
686 }
687
688 if (len == 1) { // Cannot have lone "+" or "-"
689 throw NumberFormatException.forInputString(s, radix);
690 }
691 i++;
692 }
693 long multmin = limit / radix;
694 long result = 0;
695 while (i < len) {
696 // Accumulating negatively avoids surprises near MAX_VALUE
697 int digit = Character.digit(s.charAt(i++),radix);
698 if (digit < 0 || result < multmin) {
699 throw NumberFormatException.forInputString(s, radix);
700 }
701 result *= radix;
702 if (result < limit + digit) {
703 throw NumberFormatException.forInputString(s, radix);
704 }
705 result -= digit;
706 }
707 return negative ? result : -result;
708 } else {
709 throw NumberFormatException.forInputString(s, radix);
710 }
711 }
712
713 /**
714 * Parses the {@link CharSequence} argument as a signed {@code long} in
715 * the specified {@code radix}, beginning at the specified
716 * {@code beginIndex} and extending to {@code endIndex - 1}.
717 *
718 * <p>The method does not take steps to guard against the
719 * {@code CharSequence} being mutated while parsing.
720 *
721 * @param s the {@code CharSequence} containing the {@code long}
722 * representation to be parsed
723 * @param beginIndex the beginning index, inclusive.
724 * @param endIndex the ending index, exclusive.
725 * @param radix the radix to be used while parsing {@code s}.
726 * @return the signed {@code long} represented by the subsequence in
727 * the specified radix.
728 * @throws NullPointerException if {@code s} is null.
729 * @throws IndexOutOfBoundsException if {@code beginIndex} is
730 * negative, or if {@code beginIndex} is greater than
731 * {@code endIndex} or if {@code endIndex} is greater than
732 * {@code s.length()}.
733 * @throws NumberFormatException if the {@code CharSequence} does not
734 * contain a parsable {@code int} in the specified
735 * {@code radix}, or if {@code radix} is either smaller than
736 * {@link java.lang.Character#MIN_RADIX} or larger than
737 * {@link java.lang.Character#MAX_RADIX}.
738 * @since 9
739 */
740 public static long parseLong(CharSequence s, int beginIndex, int endIndex, int radix)
741 throws NumberFormatException {
742 s = Objects.requireNonNull(s);
743
744 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
745 throw new IndexOutOfBoundsException();
746 }
747 if (radix < Character.MIN_RADIX) {
748 throw new NumberFormatException("radix " + radix +
749 " less than Character.MIN_RADIX");
750 }
751 if (radix > Character.MAX_RADIX) {
752 throw new NumberFormatException("radix " + radix +
753 " greater than Character.MAX_RADIX");
754 }
755
756 boolean negative = false;
757 int i = beginIndex;
758 long limit = -Long.MAX_VALUE;
759
760 if (i < endIndex) {
761 char firstChar = s.charAt(i);
762 if (firstChar < '0') { // Possible leading "+" or "-"
763 if (firstChar == '-') {
764 negative = true;
765 limit = Long.MIN_VALUE;
766 } else if (firstChar != '+') {
767 throw NumberFormatException.forCharSequence(s, beginIndex,
768 endIndex, i);
769 }
770 i++;
771 }
772 if (i >= endIndex) { // Cannot have lone "+", "-" or ""
773 throw NumberFormatException.forCharSequence(s, beginIndex,
774 endIndex, i);
775 }
776 long multmin = limit / radix;
777 long result = 0;
778 while (i < endIndex) {
779 // Accumulating negatively avoids surprises near MAX_VALUE
780 int digit = Character.digit(s.charAt(i), radix);
781 if (digit < 0 || result < multmin) {
782 throw NumberFormatException.forCharSequence(s, beginIndex,
783 endIndex, i);
784 }
785 result *= radix;
786 if (result < limit + digit) {
787 throw NumberFormatException.forCharSequence(s, beginIndex,
788 endIndex, i);
789 }
790 i++;
791 result -= digit;
792 }
793 return negative ? result : -result;
794 } else {
795 throw new NumberFormatException("");
796 }
797 }
798
799 /**
800 * Parses the string argument as a signed decimal {@code long}.
801 * The characters in the string must all be decimal digits, except
802 * that the first character may be an ASCII minus sign {@code '-'}
803 * ({@code \u005Cu002D'}) to indicate a negative value or an
804 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
805 * indicate a positive value. The resulting {@code long} value is
806 * returned, exactly as if the argument and the radix {@code 10}
807 * were given as arguments to the {@link
808 * #parseLong(java.lang.String, int)} method.
809 *
810 * <p>Note that neither the character {@code L}
811 * ({@code '\u005Cu004C'}) nor {@code l}
812 * ({@code '\u005Cu006C'}) is permitted to appear at the end
813 * of the string as a type indicator, as would be permitted in
814 * Java programming language source code.
815 *
816 * @param s a {@code String} containing the {@code long}
817 * representation to be parsed
818 * @return the {@code long} represented by the argument in
819 * decimal.
820 * @throws NumberFormatException if the string does not contain a
821 * parsable {@code long}.
822 */
823 public static long parseLong(String s) throws NumberFormatException {
824 return parseLong(s, 10);
825 }
826
827 /**
828 * Parses the string argument as an unsigned {@code long} in the
829 * radix specified by the second argument. An unsigned integer
830 * maps the values usually associated with negative numbers to
831 * positive numbers larger than {@code MAX_VALUE}.
832 *
833 * The characters in the string must all be digits of the
834 * specified radix (as determined by whether {@link
835 * java.lang.Character#digit(char, int)} returns a nonnegative
836 * value), except that the first character may be an ASCII plus
837 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
838 * integer value is returned.
839 *
840 * <p>An exception of type {@code NumberFormatException} is
841 * thrown if any of the following situations occurs:
842 * <ul>
843 * <li>The first argument is {@code null} or is a string of
844 * length zero.
845 *
846 * <li>The radix is either smaller than
847 * {@link java.lang.Character#MIN_RADIX} or
848 * larger than {@link java.lang.Character#MAX_RADIX}.
849 *
850 * <li>Any character of the string is not a digit of the specified
851 * radix, except that the first character may be a plus sign
852 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
853 * string is longer than length 1.
854 *
855 * <li>The value represented by the string is larger than the
856 * largest unsigned {@code long}, 2<sup>64</sup>-1.
857 *
858 * </ul>
859 *
860 *
861 * @param s the {@code String} containing the unsigned integer
862 * representation to be parsed
863 * @param radix the radix to be used while parsing {@code s}.
864 * @return the unsigned {@code long} represented by the string
865 * argument in the specified radix.
866 * @throws NumberFormatException if the {@code String}
867 * does not contain a parsable {@code long}.
868 * @since 1.8
869 */
870 public static long parseUnsignedLong(String s, int radix)
871 throws NumberFormatException {
872 if (s == null) {
873 throw new NumberFormatException("null");
874 }
875
876 int len = s.length();
877 if (len > 0) {
878 char firstChar = s.charAt(0);
879 if (firstChar == '-') {
880 throw new
881 NumberFormatException(String.format("Illegal leading minus sign " +
882 "on unsigned string %s.", s));
883 } else {
884 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
885 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
886 return parseLong(s, radix);
887 }
888
889 // No need for range checks on len due to testing above.
890 long first = parseLong(s, 0, len - 1, radix);
891 int second = Character.digit(s.charAt(len - 1), radix);
892 if (second < 0) {
893 throw new NumberFormatException("Bad digit at end of " + s);
894 }
895 long result = first * radix + second;
896
897 /*
898 * Test leftmost bits of multiprecision extension of first*radix
899 * for overflow. The number of bits needed is defined by
900 * GUARD_BIT = ceil(log2(Character.MAX_RADIX)) + 1 = 7. Then
901 * int guard = radix*(int)(first >>> (64 - GUARD_BIT)) and
902 * overflow is tested by splitting guard in the ranges
903 * guard < 92, 92 <= guard < 128, and 128 <= guard, where
904 * 92 = 128 - Character.MAX_RADIX. Note that guard cannot take
905 * on a value which does not include a prime factor in the legal
906 * radix range.
907 */
908 int guard = radix * (int) (first >>> 57);
909 if (guard >= 128 ||
910 (result >= 0 && guard >= 128 - Character.MAX_RADIX)) {
911 /*
912 * For purposes of exposition, the programmatic statements
913 * below should be taken to be multi-precision, i.e., not
914 * subject to overflow.
915 *
916 * A) Condition guard >= 128:
917 * If guard >= 128 then first*radix >= 2^7 * 2^57 = 2^64
918 * hence always overflow.
919 *
920 * B) Condition guard < 92:
921 * Define left7 = first >>> 57.
922 * Given first = (left7 * 2^57) + (first & (2^57 - 1)) then
923 * result <= (radix*left7)*2^57 + radix*(2^57 - 1) + second.
924 * Thus if radix*left7 < 92, radix <= 36, and second < 36,
925 * then result < 92*2^57 + 36*(2^57 - 1) + 36 = 2^64 hence
926 * never overflow.
927 *
928 * C) Condition 92 <= guard < 128:
929 * first*radix + second >= radix*left7*2^57 + second
930 * so that first*radix + second >= 92*2^57 + 0 > 2^63
931 *
932 * D) Condition guard < 128:
933 * radix*first <= (radix*left7) * 2^57 + radix*(2^57 - 1)
934 * so
935 * radix*first + second <= (radix*left7) * 2^57 + radix*(2^57 - 1) + 36
936 * thus
937 * radix*first + second < 128 * 2^57 + 36*2^57 - radix + 36
938 * whence
939 * radix*first + second < 2^64 + 2^6*2^57 = 2^64 + 2^63
940 *
941 * E) Conditions C, D, and result >= 0:
942 * C and D combined imply the mathematical result
943 * 2^63 < first*radix + second < 2^64 + 2^63. The lower
944 * bound is therefore negative as a signed long, but the
945 * upper bound is too small to overflow again after the
946 * signed long overflows to positive above 2^64 - 1. Hence
947 * result >= 0 implies overflow given C and D.
948 */
949 throw new NumberFormatException(String.format("String value %s exceeds " +
950 "range of unsigned long.", s));
951 }
952 return result;
953 }
954 } else {
955 throw NumberFormatException.forInputString(s, radix);
956 }
957 }
958
959 /**
960 * Parses the {@link CharSequence} argument as an unsigned {@code long} in
961 * the specified {@code radix}, beginning at the specified
962 * {@code beginIndex} and extending to {@code endIndex - 1}.
963 *
964 * <p>The method does not take steps to guard against the
965 * {@code CharSequence} being mutated while parsing.
966 *
967 * @param s the {@code CharSequence} containing the unsigned
968 * {@code long} representation to be parsed
969 * @param beginIndex the beginning index, inclusive.
970 * @param endIndex the ending index, exclusive.
971 * @param radix the radix to be used while parsing {@code s}.
972 * @return the unsigned {@code long} represented by the subsequence in
973 * the specified radix.
974 * @throws NullPointerException if {@code s} is null.
975 * @throws IndexOutOfBoundsException if {@code beginIndex} is
976 * negative, or if {@code beginIndex} is greater than
977 * {@code endIndex} or if {@code endIndex} is greater than
978 * {@code s.length()}.
979 * @throws NumberFormatException if the {@code CharSequence} does not
980 * contain a parsable unsigned {@code long} in the specified
981 * {@code radix}, or if {@code radix} is either smaller than
982 * {@link java.lang.Character#MIN_RADIX} or larger than
983 * {@link java.lang.Character#MAX_RADIX}.
984 * @since 9
985 */
986 public static long parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix)
987 throws NumberFormatException {
988 s = Objects.requireNonNull(s);
989
990 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
991 throw new IndexOutOfBoundsException();
992 }
993 int start = beginIndex, len = endIndex - beginIndex;
994
995 if (len > 0) {
996 char firstChar = s.charAt(start);
997 if (firstChar == '-') {
998 throw new NumberFormatException(String.format("Illegal leading minus sign " +
999 "on unsigned string %s.", s.subSequence(start, start + len)));
1000 } else {
1001 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
1002 (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
1003 return parseLong(s, start, start + len, radix);
1004 }
1005
1006 // No need for range checks on end due to testing above.
1007 long first = parseLong(s, start, start + len - 1, radix);
1008 int second = Character.digit(s.charAt(start + len - 1), radix);
1009 if (second < 0) {
1010 throw new NumberFormatException("Bad digit at end of " +
1011 s.subSequence(start, start + len));
1012 }
1013 long result = first * radix + second;
1014
1015 /*
1016 * Test leftmost bits of multiprecision extension of first*radix
1017 * for overflow. The number of bits needed is defined by
1018 * GUARD_BIT = ceil(log2(Character.MAX_RADIX)) + 1 = 7. Then
1019 * int guard = radix*(int)(first >>> (64 - GUARD_BIT)) and
1020 * overflow is tested by splitting guard in the ranges
1021 * guard < 92, 92 <= guard < 128, and 128 <= guard, where
1022 * 92 = 128 - Character.MAX_RADIX. Note that guard cannot take
1023 * on a value which does not include a prime factor in the legal
1024 * radix range.
1025 */
1026 int guard = radix * (int) (first >>> 57);
1027 if (guard >= 128 ||
1028 (result >= 0 && guard >= 128 - Character.MAX_RADIX)) {
1029 /*
1030 * For purposes of exposition, the programmatic statements
1031 * below should be taken to be multi-precision, i.e., not
1032 * subject to overflow.
1033 *
1034 * A) Condition guard >= 128:
1035 * If guard >= 128 then first*radix >= 2^7 * 2^57 = 2^64
1036 * hence always overflow.
1037 *
1038 * B) Condition guard < 92:
1039 * Define left7 = first >>> 57.
1040 * Given first = (left7 * 2^57) + (first & (2^57 - 1)) then
1041 * result <= (radix*left7)*2^57 + radix*(2^57 - 1) + second.
1042 * Thus if radix*left7 < 92, radix <= 36, and second < 36,
1043 * then result < 92*2^57 + 36*(2^57 - 1) + 36 = 2^64 hence
1044 * never overflow.
1045 *
1046 * C) Condition 92 <= guard < 128:
1047 * first*radix + second >= radix*left7*2^57 + second
1048 * so that first*radix + second >= 92*2^57 + 0 > 2^63
1049 *
1050 * D) Condition guard < 128:
1051 * radix*first <= (radix*left7) * 2^57 + radix*(2^57 - 1)
1052 * so
1053 * radix*first + second <= (radix*left7) * 2^57 + radix*(2^57 - 1) + 36
1054 * thus
1055 * radix*first + second < 128 * 2^57 + 36*2^57 - radix + 36
1056 * whence
1057 * radix*first + second < 2^64 + 2^6*2^57 = 2^64 + 2^63
1058 *
1059 * E) Conditions C, D, and result >= 0:
1060 * C and D combined imply the mathematical result
1061 * 2^63 < first*radix + second < 2^64 + 2^63. The lower
1062 * bound is therefore negative as a signed long, but the
1063 * upper bound is too small to overflow again after the
1064 * signed long overflows to positive above 2^64 - 1. Hence
1065 * result >= 0 implies overflow given C and D.
1066 */
1067 throw new NumberFormatException(String.format("String value %s exceeds " +
1068 "range of unsigned long.", s.subSequence(start, start + len)));
1069 }
1070 return result;
1071 }
1072 } else {
1073 throw NumberFormatException.forInputString("", radix);
1074 }
1075 }
1076
1077 /**
1078 * Parses the string argument as an unsigned decimal {@code long}. The
1079 * characters in the string must all be decimal digits, except
1080 * that the first character may be an ASCII plus sign {@code
1081 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
1082 * is returned, exactly as if the argument and the radix 10 were
1083 * given as arguments to the {@link
1084 * #parseUnsignedLong(java.lang.String, int)} method.
1085 *
1086 * @param s a {@code String} containing the unsigned {@code long}
1087 * representation to be parsed
1088 * @return the unsigned {@code long} value represented by the decimal string argument
1089 * @throws NumberFormatException if the string does not contain a
1090 * parsable unsigned integer.
1091 * @since 1.8
1092 */
1093 public static long parseUnsignedLong(String s) throws NumberFormatException {
1094 return parseUnsignedLong(s, 10);
1095 }
1096
1097 /**
1098 * Returns a {@code Long} object holding the value
1099 * extracted from the specified {@code String} when parsed
1100 * with the radix given by the second argument. The first
1101 * argument is interpreted as representing a signed
1102 * {@code long} in the radix specified by the second
1103 * argument, exactly as if the arguments were given to the {@link
1104 * #parseLong(java.lang.String, int)} method. The result is a
1105 * {@code Long} object that represents the {@code long}
1106 * value specified by the string.
1107 *
1108 * <p>In other words, this method returns a {@code Long} object equal
1109 * to the value of:
1110 *
1111 * <blockquote>
1112 * {@code new Long(Long.parseLong(s, radix))}
1113 * </blockquote>
1114 *
1115 * @param s the string to be parsed
1116 * @param radix the radix to be used in interpreting {@code s}
1117 * @return a {@code Long} object holding the value
1118 * represented by the string argument in the specified
1119 * radix.
1120 * @throws NumberFormatException If the {@code String} does not
1121 * contain a parsable {@code long}.
1122 */
1123 public static Long valueOf(String s, int radix) throws NumberFormatException {
1124 return Long.valueOf(parseLong(s, radix));
1125 }
1126
1127 /**
1128 * Returns a {@code Long} object holding the value
1129 * of the specified {@code String}. The argument is
1130 * interpreted as representing a signed decimal {@code long},
1131 * exactly as if the argument were given to the {@link
1132 * #parseLong(java.lang.String)} method. The result is a
1133 * {@code Long} object that represents the integer value
1134 * specified by the string.
1135 *
1136 * <p>In other words, this method returns a {@code Long} object
1137 * equal to the value of:
1138 *
1139 * <blockquote>
1140 * {@code new Long(Long.parseLong(s))}
1141 * </blockquote>
1142 *
1143 * @param s the string to be parsed.
1144 * @return a {@code Long} object holding the value
1145 * represented by the string argument.
1146 * @throws NumberFormatException If the string cannot be parsed
1147 * as a {@code long}.
1148 */
1149 public static Long valueOf(String s) throws NumberFormatException
1150 {
1151 return Long.valueOf(parseLong(s, 10));
1152 }
1153
1154 private static class LongCache {
1155 private LongCache() {}
1156
1157 static final Long[] cache;
1158 static Long[] archivedCache;
1159
1160 static {
1161 int size = -(-128) + 127 + 1;
1162
1163 // Load and use the archived cache if it exists
1164 VM.initializeFromArchive(LongCache.class);
1165 if (archivedCache == null || archivedCache.length != size) {
1166 Long[] c = new Long[size];
1167 long value = -128;
1168 for(int i = 0; i < size; i++) {
1169 c[i] = new Long(value++);
1170 }
1171 archivedCache = c;
1172 }
1173 cache = archivedCache;
1174 }
1175 }
1176
1177 /**
1178 * Returns a {@code Long} instance representing the specified
1179 * {@code long} value.
1180 * If a new {@code Long} instance is not required, this method
1181 * should generally be used in preference to the constructor
1182 * {@link #Long(long)}, as this method is likely to yield
1183 * significantly better space and time performance by caching
1184 * frequently requested values.
1185 *
1186 * This method will always cache values in the range -128 to 127,
1187 * inclusive, and may cache other values outside of this range.
1188 *
1189 * @param l a long value.
1190 * @return a {@code Long} instance representing {@code l}.
1191 * @since 1.5
1192 */
1193 @HotSpotIntrinsicCandidate
1194 public static Long valueOf(long l) {
1195 final int offset = 128;
1196 if (l >= -128 && l <= 127) { // will cache
1197 return LongCache.cache[(int)l + offset];
1198 }
1199 return new Long(l);
1200 }
1201
1202 /**
1203 * Decodes a {@code String} into a {@code Long}.
1204 * Accepts decimal, hexadecimal, and octal numbers given by the
1205 * following grammar:
1206 *
1207 * <blockquote>
1208 * <dl>
1209 * <dt><i>DecodableString:</i>
1210 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1211 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1212 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1213 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1214 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1215 *
1216 * <dt><i>Sign:</i>
1217 * <dd>{@code -}
1218 * <dd>{@code +}
1219 * </dl>
1220 * </blockquote>
1221 *
1222 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1223 * are as defined in section 3.10.1 of
1224 * <cite>The Java™ Language Specification</cite>,
1225 * except that underscores are not accepted between digits.
1226 *
1227 * <p>The sequence of characters following an optional
1228 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1229 * "{@code #}", or leading zero) is parsed as by the {@code
1230 * Long.parseLong} method with the indicated radix (10, 16, or 8).
1231 * This sequence of characters must represent a positive value or
1232 * a {@link NumberFormatException} will be thrown. The result is
1233 * negated if first character of the specified {@code String} is
1234 * the minus sign. No whitespace characters are permitted in the
1235 * {@code String}.
1236 *
1237 * @param nm the {@code String} to decode.
1238 * @return a {@code Long} object holding the {@code long}
1239 * value represented by {@code nm}
1240 * @throws NumberFormatException if the {@code String} does not
1241 * contain a parsable {@code long}.
1242 * @see java.lang.Long#parseLong(String, int)
1243 * @since 1.2
1244 */
1245 public static Long decode(String nm) throws NumberFormatException {
1246 int radix = 10;
1247 int index = 0;
1248 boolean negative = false;
1249 Long result;
1250
1251 if (nm.length() == 0)
1252 throw new NumberFormatException("Zero length string");
1253 char firstChar = nm.charAt(0);
1254 // Handle sign, if present
1255 if (firstChar == '-') {
1256 negative = true;
1257 index++;
1258 } else if (firstChar == '+')
1259 index++;
1260
1261 // Handle radix specifier, if present
1262 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1263 index += 2;
1264 radix = 16;
1265 }
1266 else if (nm.startsWith("#", index)) {
1267 index ++;
1268 radix = 16;
1269 }
1270 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1271 index ++;
1272 radix = 8;
1273 }
1274
1275 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1276 throw new NumberFormatException("Sign character in wrong position");
1277
1278 try {
1279 result = Long.valueOf(nm.substring(index), radix);
1280 result = negative ? Long.valueOf(-result.longValue()) : result;
1281 } catch (NumberFormatException e) {
1282 // If number is Long.MIN_VALUE, we'll end up here. The next line
1283 // handles this case, and causes any genuine format error to be
1284 // rethrown.
1285 String constant = negative ? ("-" + nm.substring(index))
1286 : nm.substring(index);
1287 result = Long.valueOf(constant, radix);
1288 }
1289 return result;
1290 }
1291
1292 /**
1293 * The value of the {@code Long}.
1294 *
1295 * @serial
1296 */
1297 private final long value;
1298
1299 /**
1300 * Constructs a newly allocated {@code Long} object that
1301 * represents the specified {@code long} argument.
1302 *
1303 * @param value the value to be represented by the
1304 * {@code Long} object.
1305 *
1306 * @deprecated
1307 * It is rarely appropriate to use this constructor. The static factory
1308 * {@link #valueOf(long)} is generally a better choice, as it is
1309 * likely to yield significantly better space and time performance.
1310 */
1311 @Deprecated(since="9")
1312 public Long(long value) {
1313 this.value = value;
1314 }
1315
1316 /**
1317 * Constructs a newly allocated {@code Long} object that
1318 * represents the {@code long} value indicated by the
1319 * {@code String} parameter. The string is converted to a
1320 * {@code long} value in exactly the manner used by the
1321 * {@code parseLong} method for radix 10.
1322 *
1323 * @param s the {@code String} to be converted to a
1324 * {@code Long}.
1325 * @throws NumberFormatException if the {@code String} does not
1326 * contain a parsable {@code long}.
1327 *
1328 * @deprecated
1329 * It is rarely appropriate to use this constructor.
1330 * Use {@link #parseLong(String)} to convert a string to a
1331 * {@code long} primitive, or use {@link #valueOf(String)}
1332 * to convert a string to a {@code Long} object.
1333 */
1334 @Deprecated(since="9")
1335 public Long(String s) throws NumberFormatException {
1336 this.value = parseLong(s, 10);
1337 }
1338
1339 /**
1340 * Returns the value of this {@code Long} as a {@code byte} after
1341 * a narrowing primitive conversion.
1342 * @jls 5.1.3 Narrowing Primitive Conversions
1343 */
1344 public byte byteValue() {
1345 return (byte)value;
1346 }
1347
1348 /**
1349 * Returns the value of this {@code Long} as a {@code short} after
1350 * a narrowing primitive conversion.
1351 * @jls 5.1.3 Narrowing Primitive Conversions
1352 */
1353 public short shortValue() {
1354 return (short)value;
1355 }
1356
1357 /**
1358 * Returns the value of this {@code Long} as an {@code int} after
1359 * a narrowing primitive conversion.
1360 * @jls 5.1.3 Narrowing Primitive Conversions
1361 */
1362 public int intValue() {
1363 return (int)value;
1364 }
1365
1366 /**
1367 * Returns the value of this {@code Long} as a
1368 * {@code long} value.
1369 */
1370 @HotSpotIntrinsicCandidate
1371 public long longValue() {
1372 return value;
1373 }
1374
1375 /**
1376 * Returns the value of this {@code Long} as a {@code float} after
1377 * a widening primitive conversion.
1378 * @jls 5.1.2 Widening Primitive Conversions
1379 */
1380 public float floatValue() {
1381 return (float)value;
1382 }
1383
1384 /**
1385 * Returns the value of this {@code Long} as a {@code double}
1386 * after a widening primitive conversion.
1387 * @jls 5.1.2 Widening Primitive Conversions
1388 */
1389 public double doubleValue() {
1390 return (double)value;
1391 }
1392
1393 /**
1394 * Returns a {@code String} object representing this
1395 * {@code Long}'s value. The value is converted to signed
1396 * decimal representation and returned as a string, exactly as if
1397 * the {@code long} value were given as an argument to the
1398 * {@link java.lang.Long#toString(long)} method.
1399 *
1400 * @return a string representation of the value of this object in
1401 * base 10.
1402 */
1403 public String toString() {
1404 return toString(value);
1405 }
1406
1407 /**
1408 * Returns a hash code for this {@code Long}. The result is
1409 * the exclusive OR of the two halves of the primitive
1410 * {@code long} value held by this {@code Long}
1411 * object. That is, the hashcode is the value of the expression:
1412 *
1413 * <blockquote>
1414 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1415 * </blockquote>
1416 *
1417 * @return a hash code value for this object.
1418 */
1419 @Override
1420 public int hashCode() {
1421 return Long.hashCode(value);
1422 }
1423
1424 /**
1425 * Returns a hash code for a {@code long} value; compatible with
1426 * {@code Long.hashCode()}.
1427 *
1428 * @param value the value to hash
1429 * @return a hash code value for a {@code long} value.
1430 * @since 1.8
1431 */
1432 public static int hashCode(long value) {
1433 return (int)(value ^ (value >>> 32));
1434 }
1435
1436 /**
1437 * Compares this object to the specified object. The result is
1438 * {@code true} if and only if the argument is not
1439 * {@code null} and is a {@code Long} object that
1440 * contains the same {@code long} value as this object.
1441 *
1442 * @param obj the object to compare with.
1443 * @return {@code true} if the objects are the same;
1444 * {@code false} otherwise.
1445 */
1446 public boolean equals(Object obj) {
1447 if (obj instanceof Long) {
1448 return value == ((Long)obj).longValue();
1449 }
1450 return false;
1451 }
1452
1453 /**
1454 * Determines the {@code long} value of the system property
1455 * with the specified name.
1456 *
1457 * <p>The first argument is treated as the name of a system
1458 * property. System properties are accessible through the {@link
1459 * java.lang.System#getProperty(java.lang.String)} method. The
1460 * string value of this property is then interpreted as a {@code
1461 * long} value using the grammar supported by {@link Long#decode decode}
1462 * and a {@code Long} object representing this value is returned.
1463 *
1464 * <p>If there is no property with the specified name, if the
1465 * specified name is empty or {@code null}, or if the property
1466 * does not have the correct numeric format, then {@code null} is
1467 * returned.
1468 *
1469 * <p>In other words, this method returns a {@code Long} object
1470 * equal to the value of:
1471 *
1472 * <blockquote>
1473 * {@code getLong(nm, null)}
1474 * </blockquote>
1475 *
1476 * @param nm property name.
1477 * @return the {@code Long} value of the property.
1478 * @throws SecurityException for the same reasons as
1479 * {@link System#getProperty(String) System.getProperty}
1480 * @see java.lang.System#getProperty(java.lang.String)
1481 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1482 */
1483 public static Long getLong(String nm) {
1484 return getLong(nm, null);
1485 }
1486
1487 /**
1488 * Determines the {@code long} value of the system property
1489 * with the specified name.
1490 *
1491 * <p>The first argument is treated as the name of a system
1492 * property. System properties are accessible through the {@link
1493 * java.lang.System#getProperty(java.lang.String)} method. The
1494 * string value of this property is then interpreted as a {@code
1495 * long} value using the grammar supported by {@link Long#decode decode}
1496 * and a {@code Long} object representing this value is returned.
1497 *
1498 * <p>The second argument is the default value. A {@code Long} object
1499 * that represents the value of the second argument is returned if there
1500 * is no property of the specified name, if the property does not have
1501 * the correct numeric format, or if the specified name is empty or null.
1502 *
1503 * <p>In other words, this method returns a {@code Long} object equal
1504 * to the value of:
1505 *
1506 * <blockquote>
1507 * {@code getLong(nm, new Long(val))}
1508 * </blockquote>
1509 *
1510 * but in practice it may be implemented in a manner such as:
1511 *
1512 * <blockquote><pre>
1513 * Long result = getLong(nm, null);
1514 * return (result == null) ? new Long(val) : result;
1515 * </pre></blockquote>
1516 *
1517 * to avoid the unnecessary allocation of a {@code Long} object when
1518 * the default value is not needed.
1519 *
1520 * @param nm property name.
1521 * @param val default value.
1522 * @return the {@code Long} value of the property.
1523 * @throws SecurityException for the same reasons as
1524 * {@link System#getProperty(String) System.getProperty}
1525 * @see java.lang.System#getProperty(java.lang.String)
1526 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1527 */
1528 public static Long getLong(String nm, long val) {
1529 Long result = Long.getLong(nm, null);
1530 return (result == null) ? Long.valueOf(val) : result;
1531 }
1532
1533 /**
1534 * Returns the {@code long} value of the system property with
1535 * the specified name. The first argument is treated as the name
1536 * of a system property. System properties are accessible through
1537 * the {@link java.lang.System#getProperty(java.lang.String)}
1538 * method. The string value of this property is then interpreted
1539 * as a {@code long} value, as per the
1540 * {@link Long#decode decode} method, and a {@code Long} object
1541 * representing this value is returned; in summary:
1542 *
1543 * <ul>
1544 * <li>If the property value begins with the two ASCII characters
1545 * {@code 0x} or the ASCII character {@code #}, not followed by
1546 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1547 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1548 * with radix 16.
1549 * <li>If the property value begins with the ASCII character
1550 * {@code 0} followed by another character, it is parsed as
1551 * an octal integer exactly as by the method {@link
1552 * #valueOf(java.lang.String, int)} with radix 8.
1553 * <li>Otherwise the property value is parsed as a decimal
1554 * integer exactly as by the method
1555 * {@link #valueOf(java.lang.String, int)} with radix 10.
1556 * </ul>
1557 *
1558 * <p>Note that, in every case, neither {@code L}
1559 * ({@code '\u005Cu004C'}) nor {@code l}
1560 * ({@code '\u005Cu006C'}) is permitted to appear at the end
1561 * of the property value as a type indicator, as would be
1562 * permitted in Java programming language source code.
1563 *
1564 * <p>The second argument is the default value. The default value is
1565 * returned if there is no property of the specified name, if the
1566 * property does not have the correct numeric format, or if the
1567 * specified name is empty or {@code null}.
1568 *
1569 * @param nm property name.
1570 * @param val default value.
1571 * @return the {@code Long} value of the property.
1572 * @throws SecurityException for the same reasons as
1573 * {@link System#getProperty(String) System.getProperty}
1574 * @see System#getProperty(java.lang.String)
1575 * @see System#getProperty(java.lang.String, java.lang.String)
1576 */
1577 public static Long getLong(String nm, Long val) {
1578 String v = null;
1579 try {
1580 v = System.getProperty(nm);
1581 } catch (IllegalArgumentException | NullPointerException e) {
1582 }
1583 if (v != null) {
1584 try {
1585 return Long.decode(v);
1586 } catch (NumberFormatException e) {
1587 }
1588 }
1589 return val;
1590 }
1591
1592 /**
1593 * Compares two {@code Long} objects numerically.
1594 *
1595 * @param anotherLong the {@code Long} to be compared.
1596 * @return the value {@code 0} if this {@code Long} is
1597 * equal to the argument {@code Long}; a value less than
1598 * {@code 0} if this {@code Long} is numerically less
1599 * than the argument {@code Long}; and a value greater
1600 * than {@code 0} if this {@code Long} is numerically
1601 * greater than the argument {@code Long} (signed
1602 * comparison).
1603 * @since 1.2
1604 */
1605 public int compareTo(Long anotherLong) {
1606 return compare(this.value, anotherLong.value);
1607 }
1608
1609 /**
1610 * Compares two {@code long} values numerically.
1611 * The value returned is identical to what would be returned by:
1612 * <pre>
1613 * Long.valueOf(x).compareTo(Long.valueOf(y))
1614 * </pre>
1615 *
1616 * @param x the first {@code long} to compare
1617 * @param y the second {@code long} to compare
1618 * @return the value {@code 0} if {@code x == y};
1619 * a value less than {@code 0} if {@code x < y}; and
1620 * a value greater than {@code 0} if {@code x > y}
1621 * @since 1.7
1622 */
1623 public static int compare(long x, long y) {
1624 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1625 }
1626
1627 /**
1628 * Compares two {@code long} values numerically treating the values
1629 * as unsigned.
1630 *
1631 * @param x the first {@code long} to compare
1632 * @param y the second {@code long} to compare
1633 * @return the value {@code 0} if {@code x == y}; a value less
1634 * than {@code 0} if {@code x < y} as unsigned values; and
1635 * a value greater than {@code 0} if {@code x > y} as
1636 * unsigned values
1637 * @since 1.8
1638 */
1639 public static int compareUnsigned(long x, long y) {
1640 return compare(x + MIN_VALUE, y + MIN_VALUE);
1641 }
1642
1643
1644 /**
1645 * Returns the unsigned quotient of dividing the first argument by
1646 * the second where each argument and the result is interpreted as
1647 * an unsigned value.
1648 *
1649 * <p>Note that in two's complement arithmetic, the three other
1650 * basic arithmetic operations of add, subtract, and multiply are
1651 * bit-wise identical if the two operands are regarded as both
1652 * being signed or both being unsigned. Therefore separate {@code
1653 * addUnsigned}, etc. methods are not provided.
1654 *
1655 * @param dividend the value to be divided
1656 * @param divisor the value doing the dividing
1657 * @return the unsigned quotient of the first argument divided by
1658 * the second argument
1659 * @see #remainderUnsigned
1660 * @since 1.8
1661 */
1662 public static long divideUnsigned(long dividend, long divisor) {
1663 if (divisor < 0L) { // signed comparison
1664 // Answer must be 0 or 1 depending on relative magnitude
1665 // of dividend and divisor.
1666 return (compareUnsigned(dividend, divisor)) < 0 ? 0L :1L;
1667 }
1668
1669 if (dividend > 0) // Both inputs non-negative
1670 return dividend/divisor;
1671 else {
1672 /*
1673 * For simple code, leveraging BigInteger. Longer and faster
1674 * code written directly in terms of operations on longs is
1675 * possible; see "Hacker's Delight" for divide and remainder
1676 * algorithms.
1677 */
1678 return toUnsignedBigInteger(dividend).
1679 divide(toUnsignedBigInteger(divisor)).longValue();
1680 }
1681 }
1682
1683 /**
1684 * Returns the unsigned remainder from dividing the first argument
1685 * by the second where each argument and the result is interpreted
1686 * as an unsigned value.
1687 *
1688 * @param dividend the value to be divided
1689 * @param divisor the value doing the dividing
1690 * @return the unsigned remainder of the first argument divided by
1691 * the second argument
1692 * @see #divideUnsigned
1693 * @since 1.8
1694 */
1695 public static long remainderUnsigned(long dividend, long divisor) {
1696 if (dividend > 0 && divisor > 0) { // signed comparisons
1697 return dividend % divisor;
1698 } else {
1699 if (compareUnsigned(dividend, divisor) < 0) // Avoid explicit check for 0 divisor
1700 return dividend;
1701 else
1702 return toUnsignedBigInteger(dividend).
1703 remainder(toUnsignedBigInteger(divisor)).longValue();
1704 }
1705 }
1706
1707 // Bit Twiddling
1708
1709 /**
1710 * The number of bits used to represent a {@code long} value in two's
1711 * complement binary form.
1712 *
1713 * @since 1.5
1714 */
1715 @Native public static final int SIZE = 64;
1716
1717 /**
1718 * The number of bytes used to represent a {@code long} value in two's
1719 * complement binary form.
1720 *
1721 * @since 1.8
1722 */
1723 public static final int BYTES = SIZE / Byte.SIZE;
1724
1725 /**
1726 * Returns a {@code long} value with at most a single one-bit, in the
1727 * position of the highest-order ("leftmost") one-bit in the specified
1728 * {@code long} value. Returns zero if the specified value has no
1729 * one-bits in its two's complement binary representation, that is, if it
1730 * is equal to zero.
1731 *
1732 * @param i the value whose highest one bit is to be computed
1733 * @return a {@code long} value with a single one-bit, in the position
1734 * of the highest-order one-bit in the specified value, or zero if
1735 * the specified value is itself equal to zero.
1736 * @since 1.5
1737 */
1738 public static long highestOneBit(long i) {
1739 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1740 }
1741
1742 /**
1743 * Returns a {@code long} value with at most a single one-bit, in the
1744 * position of the lowest-order ("rightmost") one-bit in the specified
1745 * {@code long} value. Returns zero if the specified value has no
1746 * one-bits in its two's complement binary representation, that is, if it
1747 * is equal to zero.
1748 *
1749 * @param i the value whose lowest one bit is to be computed
1750 * @return a {@code long} value with a single one-bit, in the position
1751 * of the lowest-order one-bit in the specified value, or zero if
1752 * the specified value is itself equal to zero.
1753 * @since 1.5
1754 */
1755 public static long lowestOneBit(long i) {
1756 // HD, Section 2-1
1757 return i & -i;
1758 }
1759
1760 /**
1761 * Returns the number of zero bits preceding the highest-order
1762 * ("leftmost") one-bit in the two's complement binary representation
1763 * of the specified {@code long} value. Returns 64 if the
1764 * specified value has no one-bits in its two's complement representation,
1765 * in other words if it is equal to zero.
1766 *
1767 * <p>Note that this method is closely related to the logarithm base 2.
1768 * For all positive {@code long} values x:
1769 * <ul>
1770 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1771 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1772 * </ul>
1773 *
1774 * @param i the value whose number of leading zeros is to be computed
1775 * @return the number of zero bits preceding the highest-order
1776 * ("leftmost") one-bit in the two's complement binary representation
1777 * of the specified {@code long} value, or 64 if the value
1778 * is equal to zero.
1779 * @since 1.5
1780 */
1781 @HotSpotIntrinsicCandidate
1782 public static int numberOfLeadingZeros(long i) {
1783 int x = (int)(i >>> 32);
1784 return x == 0 ? 32 + Integer.numberOfLeadingZeros((int)i)
1785 : Integer.numberOfLeadingZeros(x);
1786 }
1787
1788 /**
1789 * Returns the number of zero bits following the lowest-order ("rightmost")
1790 * one-bit in the two's complement binary representation of the specified
1791 * {@code long} value. Returns 64 if the specified value has no
1792 * one-bits in its two's complement representation, in other words if it is
1793 * equal to zero.
1794 *
1795 * @param i the value whose number of trailing zeros is to be computed
1796 * @return the number of zero bits following the lowest-order ("rightmost")
1797 * one-bit in the two's complement binary representation of the
1798 * specified {@code long} value, or 64 if the value is equal
1799 * to zero.
1800 * @since 1.5
1801 */
1802 @HotSpotIntrinsicCandidate
1803 public static int numberOfTrailingZeros(long i) {
1804 int x = (int)i;
1805 return x == 0 ? 32 + Integer.numberOfTrailingZeros((int)(i >>> 32))
1806 : Integer.numberOfTrailingZeros(x);
1807 }
1808
1809 /**
1810 * Returns the number of one-bits in the two's complement binary
1811 * representation of the specified {@code long} value. This function is
1812 * sometimes referred to as the <i>population count</i>.
1813 *
1814 * @param i the value whose bits are to be counted
1815 * @return the number of one-bits in the two's complement binary
1816 * representation of the specified {@code long} value.
1817 * @since 1.5
1818 */
1819 @HotSpotIntrinsicCandidate
1820 public static int bitCount(long i) {
1821 // HD, Figure 5-2
1822 i = i - ((i >>> 1) & 0x5555555555555555L);
1823 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1824 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1825 i = i + (i >>> 8);
1826 i = i + (i >>> 16);
1827 i = i + (i >>> 32);
1828 return (int)i & 0x7f;
1829 }
1830
1831 /**
1832 * Returns the value obtained by rotating the two's complement binary
1833 * representation of the specified {@code long} value left by the
1834 * specified number of bits. (Bits shifted out of the left hand, or
1835 * high-order, side reenter on the right, or low-order.)
1836 *
1837 * <p>Note that left rotation with a negative distance is equivalent to
1838 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1839 * distance)}. Note also that rotation by any multiple of 64 is a
1840 * no-op, so all but the last six bits of the rotation distance can be
1841 * ignored, even if the distance is negative: {@code rotateLeft(val,
1842 * distance) == rotateLeft(val, distance & 0x3F)}.
1843 *
1844 * @param i the value whose bits are to be rotated left
1845 * @param distance the number of bit positions to rotate left
1846 * @return the value obtained by rotating the two's complement binary
1847 * representation of the specified {@code long} value left by the
1848 * specified number of bits.
1849 * @since 1.5
1850 */
1851 public static long rotateLeft(long i, int distance) {
1852 return (i << distance) | (i >>> -distance);
1853 }
1854
1855 /**
1856 * Returns the value obtained by rotating the two's complement binary
1857 * representation of the specified {@code long} value right by the
1858 * specified number of bits. (Bits shifted out of the right hand, or
1859 * low-order, side reenter on the left, or high-order.)
1860 *
1861 * <p>Note that right rotation with a negative distance is equivalent to
1862 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1863 * distance)}. Note also that rotation by any multiple of 64 is a
1864 * no-op, so all but the last six bits of the rotation distance can be
1865 * ignored, even if the distance is negative: {@code rotateRight(val,
1866 * distance) == rotateRight(val, distance & 0x3F)}.
1867 *
1868 * @param i the value whose bits are to be rotated right
1869 * @param distance the number of bit positions to rotate right
1870 * @return the value obtained by rotating the two's complement binary
1871 * representation of the specified {@code long} value right by the
1872 * specified number of bits.
1873 * @since 1.5
1874 */
1875 public static long rotateRight(long i, int distance) {
1876 return (i >>> distance) | (i << -distance);
1877 }
1878
1879 /**
1880 * Returns the value obtained by reversing the order of the bits in the
1881 * two's complement binary representation of the specified {@code long}
1882 * value.
1883 *
1884 * @param i the value to be reversed
1885 * @return the value obtained by reversing order of the bits in the
1886 * specified {@code long} value.
1887 * @since 1.5
1888 */
1889 public static long reverse(long i) {
1890 // HD, Figure 7-1
1891 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1892 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1893 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1894
1895 return reverseBytes(i);
1896 }
1897
1898 /**
1899 * Returns the signum function of the specified {@code long} value. (The
1900 * return value is -1 if the specified value is negative; 0 if the
1901 * specified value is zero; and 1 if the specified value is positive.)
1902 *
1903 * @param i the value whose signum is to be computed
1904 * @return the signum function of the specified {@code long} value.
1905 * @since 1.5
1906 */
1907 public static int signum(long i) {
1908 // HD, Section 2-7
1909 return (int) ((i >> 63) | (-i >>> 63));
1910 }
1911
1912 /**
1913 * Returns the value obtained by reversing the order of the bytes in the
1914 * two's complement representation of the specified {@code long} value.
1915 *
1916 * @param i the value whose bytes are to be reversed
1917 * @return the value obtained by reversing the bytes in the specified
1918 * {@code long} value.
1919 * @since 1.5
1920 */
1921 @HotSpotIntrinsicCandidate
1922 public static long reverseBytes(long i) {
1923 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1924 return (i << 48) | ((i & 0xffff0000L) << 16) |
1925 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1926 }
1927
1928 /**
1929 * Adds two {@code long} values together as per the + operator.
1930 *
1931 * @param a the first operand
1932 * @param b the second operand
1933 * @return the sum of {@code a} and {@code b}
1934 * @see java.util.function.BinaryOperator
1935 * @since 1.8
1936 */
1937 public static long sum(long a, long b) {
1938 return a + b;
1939 }
1940
1941 /**
1942 * Returns the greater of two {@code long} values
1943 * as if by calling {@link Math#max(long, long) Math.max}.
1944 *
1945 * @param a the first operand
1946 * @param b the second operand
1947 * @return the greater of {@code a} and {@code b}
1948 * @see java.util.function.BinaryOperator
1949 * @since 1.8
1950 */
1951 public static long max(long a, long b) {
1952 return Math.max(a, b);
1953 }
1954
1955 /**
1956 * Returns the smaller of two {@code long} values
1957 * as if by calling {@link Math#min(long, long) Math.min}.
1958 *
1959 * @param a the first operand
1960 * @param b the second operand
1961 * @return the smaller of {@code a} and {@code b}
1962 * @see java.util.function.BinaryOperator
1963 * @since 1.8
1964 */
1965 public static long min(long a, long b) {
1966 return Math.min(a, b);
1967 }
1968
1969 /**
1970 * Returns a nominal descriptor for this instance, which is the instance
1971 * itself.
1972 *
1973 * @return an {@link Optional} describing the {@linkplain Long} instance
1974 * @since 12
1975 */
1976 @Override
1977 public Optional<Long> describeConstable() {
1978 return Optional.of(this);
1979 }
1980
1981 /**
1982 * Resolves this instance as a {@link ConstantDesc}, the result of which is
1983 * the instance itself.
1984 *
1985 * @param lookup ignored
1986 * @return the {@linkplain Long} instance
1987 * @since 12
1988 */
1989 @Override
1990 public Long resolveConstantDesc(MethodHandles.Lookup lookup) {
1991 return this;
1992 }
1993
1994 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1995 @Native private static final long serialVersionUID = 4290774380558885855L;
1996 }