1 /*
2 * Copyright (c) 1994, 2025, 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.misc.CDS;
37 import jdk.internal.misc.PreviewFeatures;
38 import jdk.internal.value.DeserializeConstructor;
39 import jdk.internal.util.DecimalDigits;
40 import jdk.internal.vm.annotation.AOTSafeClassInitializer;
41 import jdk.internal.vm.annotation.ForceInline;
42 import jdk.internal.vm.annotation.IntrinsicCandidate;
43 import jdk.internal.vm.annotation.Stable;
44
45 import static java.lang.Character.digit;
46 import static java.lang.String.COMPACT_STRINGS;
47
48 /**
49 * The {@code Long} class is the {@linkplain
50 * java.lang##wrapperClass wrapper class} for values of the primitive
51 * type {@code long}. An object of type {@code Long} contains a
52 * single field whose type is {@code long}.
53 *
54 * <p> In addition, this class provides several methods for converting
55 * a {@code long} to a {@code String} and a {@code String} to a {@code
56 * long}, as well as other constants and methods useful when dealing
57 * with a {@code long}.
58 *
59 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
60 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
61 * as interchangeable and should not use instances for synchronization, mutexes, or
62 * with {@linkplain java.lang.ref.Reference object references}.
63 *
64 * <div class="preview-block">
65 * <div class="preview-comment">
66 * When preview features are enabled, {@code Long} is a {@linkplain Class#isValue value class}.
67 * Use of value class instances for synchronization, mutexes, or with
68 * {@linkplain java.lang.ref.Reference object references} result in
69 * {@link IdentityException}.
70 * </div>
71 * </div>
72 *
73 *
74 * <p>Implementation note: The implementations of the "bit twiddling"
75 * methods (such as {@link #highestOneBit(long) highestOneBit} and
76 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
77 * based on material from Henry S. Warren, Jr.'s <cite>Hacker's
78 * Delight</cite>, (Addison Wesley, 2002) and <cite>Hacker's
79 * Delight, Second Edition</cite>, (Pearson Education, 2013).
80 *
81 * @since 1.0
82 */
83 @jdk.internal.MigratedValueClass
84 @jdk.internal.ValueBased
85 public final class Long extends Number
86 implements Comparable<Long>, Constable, ConstantDesc {
87 /**
88 * A constant holding the minimum value a {@code long} can
89 * have, -2<sup>63</sup>.
90 */
91 @Native public static final long MIN_VALUE = 0x8000000000000000L;
92
93 /**
94 * A constant holding the maximum value a {@code long} can
95 * have, 2<sup>63</sup>-1.
96 */
97 @Native public static final long MAX_VALUE = 0x7fffffffffffffffL;
98
99 /**
100 * The {@code Class} instance representing the primitive type
101 * {@code long}.
102 *
103 * @since 1.1
104 */
105 public static final Class<Long> TYPE = Class.getPrimitiveClass("long");
106
107 /**
108 * Returns a string representation of the first argument in the
109 * radix specified by the second argument.
110 *
111 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
112 * or larger than {@code Character.MAX_RADIX}, then the radix
113 * {@code 10} is used instead.
114 *
115 * <p>If the first argument is negative, the first element of the
116 * result is the ASCII minus sign {@code '-'}
117 * ({@code '\u005Cu002d'}). If the first argument is not
118 * negative, no sign character appears in the result.
119 *
120 * <p>The remaining characters of the result represent the magnitude
121 * of the first argument. If the magnitude is zero, it is
122 * represented by a single zero character {@code '0'}
123 * ({@code '\u005Cu0030'}); otherwise, the first character of
124 * the representation of the magnitude will not be the zero
125 * character. The following ASCII characters are used as digits:
126 *
127 * <blockquote>
128 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
129 * </blockquote>
130 *
131 * These are {@code '\u005Cu0030'} through
132 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
133 * {@code '\u005Cu007a'}. If {@code radix} is
134 * <var>N</var>, then the first <var>N</var> of these characters
135 * are used as radix-<var>N</var> digits in the order shown. Thus,
136 * the digits for hexadecimal (radix 16) are
137 * {@code 0123456789abcdef}. If uppercase letters are
138 * desired, the {@link java.lang.String#toUpperCase()} method may
139 * be called on the result:
140 *
141 * <blockquote>
142 * {@code Long.toString(n, 16).toUpperCase()}
143 * </blockquote>
144 *
145 * @param i a {@code long} to be converted to a string.
146 * @param radix the radix to use in the string representation.
147 * @return a string representation of the argument in the specified radix.
148 * @see java.lang.Character#MAX_RADIX
149 * @see java.lang.Character#MIN_RADIX
150 */
151 public static String toString(long i, int radix) {
152 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
153 radix = 10;
154 if (radix == 10)
155 return toString(i);
156
157 if (COMPACT_STRINGS) {
158 byte[] buf = new byte[65];
159 int charPos = 64;
160 boolean negative = (i < 0);
161
162 if (!negative) {
163 i = -i;
164 }
165
166 while (i <= -radix) {
167 buf[charPos--] = Integer.digits[(int)(-(i % radix))];
168 i = i / radix;
169 }
170 buf[charPos] = Integer.digits[(int)(-i)];
171
172 if (negative) {
173 buf[--charPos] = '-';
174 }
175 return StringLatin1.newString(buf, charPos, (65 - charPos));
176 }
177 return toStringUTF16(i, radix);
178 }
179
180 private static String toStringUTF16(long i, int radix) {
181 byte[] buf = new byte[65 * 2];
182 int charPos = 64;
183 boolean negative = (i < 0);
184 if (!negative) {
185 i = -i;
186 }
187 while (i <= -radix) {
188 StringUTF16.putChar(buf, charPos--, Integer.digits[(int)(-(i % radix))]);
189 i = i / radix;
190 }
191 StringUTF16.putChar(buf, charPos, Integer.digits[(int)(-i)]);
192 if (negative) {
193 StringUTF16.putChar(buf, --charPos, '-');
194 }
195 return StringUTF16.newString(buf, charPos, (65 - charPos));
196 }
197
198 /**
199 * Returns a string representation of the first argument as an
200 * unsigned integer value in the radix specified by the second
201 * argument.
202 *
203 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
204 * or larger than {@code Character.MAX_RADIX}, then the radix
205 * {@code 10} is used instead.
206 *
207 * <p>Note that since the first argument is treated as an unsigned
208 * value, no leading sign character is printed.
209 *
210 * <p>If the magnitude is zero, it is represented by a single zero
211 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
212 * the first character of the representation of the magnitude will
213 * not be the zero character.
214 *
215 * <p>The behavior of radixes and the characters used as digits
216 * are the same as {@link #toString(long, int) toString}.
217 *
218 * @param i an integer to be converted to an unsigned string.
219 * @param radix the radix to use in the string representation.
220 * @return an unsigned string representation of the argument in the specified radix.
221 * @see #toString(long, int)
222 * @since 1.8
223 */
224 public static String toUnsignedString(long i, int radix) {
225 if (i >= 0)
226 return toString(i, radix);
227 else {
228 return switch (radix) {
229 case 2 -> toBinaryString(i);
230 case 4 -> toUnsignedString0(i, 2);
231 case 8 -> toOctalString(i);
232 case 10 -> {
233 /*
234 * We can get the effect of an unsigned division by 10
235 * on a long value by first shifting right, yielding a
236 * positive value, and then dividing by 5. This
237 * allows the last digit and preceding digits to be
238 * isolated more quickly than by an initial conversion
239 * to BigInteger.
240 */
241 long quot = (i >>> 1) / 5;
242 long rem = i - quot * 10;
243 yield toString(quot) + rem;
244 }
245 case 16 -> toHexString(i);
246 case 32 -> toUnsignedString0(i, 5);
247 default -> toUnsignedBigInteger(i).toString(radix);
248 };
249 }
250 }
251
252 /**
253 * Return a BigInteger equal to the unsigned value of the
254 * argument.
255 */
256 private static BigInteger toUnsignedBigInteger(long i) {
257 if (i >= 0L)
258 return BigInteger.valueOf(i);
259 else {
260 int upper = (int) (i >>> 32);
261 int lower = (int) i;
262
263 // return (upper << 32) + lower
264 return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
265 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
266 }
267 }
268
269 /**
270 * Returns a string representation of the {@code long}
271 * argument as an unsigned integer in base 16.
272 *
273 * <p>The unsigned {@code long} value is the argument plus
274 * 2<sup>64</sup> if the argument is negative; otherwise, it is
275 * equal to the argument. This value is converted to a string of
276 * ASCII digits in hexadecimal (base 16) with no extra
277 * leading {@code 0}s.
278 *
279 * <p>The value of the argument can be recovered from the returned
280 * string {@code s} by calling {@link
281 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
282 * 16)}.
283 *
284 * <p>If the unsigned magnitude is zero, it is represented by a
285 * single zero character {@code '0'} ({@code '\u005Cu0030'});
286 * otherwise, the first character of the representation of the
287 * unsigned magnitude will not be the zero character. The
288 * following characters are used as hexadecimal digits:
289 *
290 * <blockquote>
291 * {@code 0123456789abcdef}
292 * </blockquote>
293 *
294 * These are the characters {@code '\u005Cu0030'} through
295 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
296 * {@code '\u005Cu0066'}. If uppercase letters are desired,
297 * the {@link java.lang.String#toUpperCase()} method may be called
298 * on the result:
299 *
300 * <blockquote>
301 * {@code Long.toHexString(n).toUpperCase()}
302 * </blockquote>
303 *
304 * @apiNote
305 * The {@link java.util.HexFormat} class provides formatting and parsing
306 * of byte arrays and primitives to return a string or adding to an {@link Appendable}.
307 * {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
308 * with leading zeros and for byte arrays includes for each byte
309 * a delimiter, prefix, and suffix.
310 *
311 * @param i a {@code long} to be converted to a string.
312 * @return the string representation of the unsigned {@code long}
313 * value represented by the argument in hexadecimal
314 * (base 16).
315 * @see java.util.HexFormat
316 * @see #parseUnsignedLong(String, int)
317 * @see #toUnsignedString(long, int)
318 * @since 1.0.2
319 */
320 public static String toHexString(long i) {
321 return toUnsignedString0(i, 4);
322 }
323
324 /**
325 * Returns a string representation of the {@code long}
326 * argument as an unsigned integer in base 8.
327 *
328 * <p>The unsigned {@code long} value is the argument plus
329 * 2<sup>64</sup> if the argument is negative; otherwise, it is
330 * equal to the argument. This value is converted to a string of
331 * ASCII digits in octal (base 8) with no extra leading
332 * {@code 0}s.
333 *
334 * <p>The value of the argument can be recovered from the returned
335 * string {@code s} by calling {@link
336 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
337 * 8)}.
338 *
339 * <p>If the unsigned magnitude is zero, it is represented by a
340 * single zero character {@code '0'} ({@code '\u005Cu0030'});
341 * otherwise, the first character of the representation of the
342 * unsigned magnitude will not be the zero character. The
343 * following characters are used as octal digits:
344 *
345 * <blockquote>
346 * {@code 01234567}
347 * </blockquote>
348 *
349 * These are the characters {@code '\u005Cu0030'} through
350 * {@code '\u005Cu0037'}.
351 *
352 * @param i a {@code long} to be converted to a string.
353 * @return the string representation of the unsigned {@code long}
354 * value represented by the argument in octal (base 8).
355 * @see #parseUnsignedLong(String, int)
356 * @see #toUnsignedString(long, int)
357 * @since 1.0.2
358 */
359 public static String toOctalString(long i) {
360 return toUnsignedString0(i, 3);
361 }
362
363 /**
364 * Returns a string representation of the {@code long}
365 * argument as an unsigned integer in base 2.
366 *
367 * <p>The unsigned {@code long} value is the argument plus
368 * 2<sup>64</sup> if the argument is negative; otherwise, it is
369 * equal to the argument. This value is converted to a string of
370 * ASCII digits in binary (base 2) with no extra leading
371 * {@code 0}s.
372 *
373 * <p>The value of the argument can be recovered from the returned
374 * string {@code s} by calling {@link
375 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
376 * 2)}.
377 *
378 * <p>If the unsigned magnitude is zero, it is represented by a
379 * single zero character {@code '0'} ({@code '\u005Cu0030'});
380 * otherwise, the first character of the representation of the
381 * unsigned magnitude will not be the zero character. The
382 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
383 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
384 *
385 * @param i a {@code long} to be converted to a string.
386 * @return the string representation of the unsigned {@code long}
387 * value represented by the argument in binary (base 2).
388 * @see #parseUnsignedLong(String, int)
389 * @see #toUnsignedString(long, int)
390 * @since 1.0.2
391 */
392 public static String toBinaryString(long i) {
393 return toUnsignedString0(i, 1);
394 }
395
396 /**
397 * Format a long (treated as unsigned) into a String.
398 * @param val the value to format
399 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
400 */
401 static String toUnsignedString0(long val, int shift) {
402 // assert shift > 0 && shift <=5 : "Illegal shift value";
403 int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
404 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
405 byte[] buf = new byte[chars];
406 formatUnsignedLong0(val, shift, buf, 0, chars);
407 return String.newStringWithLatin1Bytes(buf);
408 }
409
410 /**
411 * Format a long (treated as unsigned) into a byte buffer (LATIN1 version). If
412 * {@code len} exceeds the formatted ASCII representation of {@code val},
413 * {@code buf} will be padded with leading zeroes.
414 *
415 * @param val the unsigned long to format
416 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
417 * @param buf the byte buffer to write to
418 * @param offset the offset in the destination buffer to start at
419 * @param len the number of characters to write
420 */
421 private static void formatUnsignedLong0(long val, int shift, byte[] buf, int offset, int len) {
422 int charPos = offset + len;
423 int radix = 1 << shift;
424 int mask = radix - 1;
425 do {
426 buf[--charPos] = Integer.digits[((int) val) & mask];
427 val >>>= shift;
428 } while (charPos > offset);
429 }
430
431 /**
432 * Returns a {@code String} object representing the specified
433 * {@code long}. The argument is converted to signed decimal
434 * representation and returned as a string, exactly as if the
435 * argument and the radix 10 were given as arguments to the {@link
436 * #toString(long, int)} method.
437 *
438 * @param i a {@code long} to be converted.
439 * @return a string representation of the argument in base 10.
440 */
441 public static String toString(long i) {
442 int size = DecimalDigits.stringSize(i);
443 byte[] buf = new byte[size];
444 DecimalDigits.uncheckedGetCharsLatin1(i, size, buf);
445 return String.newStringWithLatin1Bytes(buf);
446 }
447
448 /**
449 * Returns a string representation of the argument as an unsigned
450 * decimal value.
451 *
452 * The argument is converted to unsigned decimal representation
453 * and returned as a string exactly as if the argument and radix
454 * 10 were given as arguments to the {@link #toUnsignedString(long,
455 * int)} method.
456 *
457 * @param i an integer to be converted to an unsigned string.
458 * @return an unsigned string representation of the argument.
459 * @see #toUnsignedString(long, int)
460 * @since 1.8
461 */
462 public static String toUnsignedString(long i) {
463 return toUnsignedString(i, 10);
464 }
465
466 /**
467 * Parses the string argument as a signed {@code long} in the
468 * radix specified by the second argument. The characters in the
469 * string must all be digits of the specified radix (as determined
470 * by whether {@link java.lang.Character#digit(char, int)} returns
471 * a nonnegative value), except that the first character may be an
472 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
473 * indicate a negative value or an ASCII plus sign {@code '+'}
474 * ({@code '\u005Cu002B'}) to indicate a positive value. The
475 * resulting {@code long} value is returned.
476 *
477 * <p>Note that neither the character {@code L}
478 * ({@code '\u005Cu004C'}) nor {@code l}
479 * ({@code '\u005Cu006C'}) is permitted to appear at the end
480 * of the string as a type indicator, as would be permitted in
481 * Java programming language source code - except that either
482 * {@code L} or {@code l} may appear as a digit for a
483 * radix greater than or equal to 22.
484 *
485 * <p>An exception of type {@code NumberFormatException} is
486 * thrown if any of the following situations occurs:
487 * <ul>
488 *
489 * <li>The first argument is {@code null} or is a string of
490 * length zero.
491 *
492 * <li>The {@code radix} is either smaller than {@link
493 * java.lang.Character#MIN_RADIX} or larger than {@link
494 * java.lang.Character#MAX_RADIX}.
495 *
496 * <li>Any character of the string is not a digit of the specified
497 * radix, except that the first character may be a minus sign
498 * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
499 * '+'} ({@code '\u005Cu002B'}) provided that the string is
500 * longer than length 1.
501 *
502 * <li>The value represented by the string is not a value of type
503 * {@code long}.
504 * </ul>
505 *
506 * <p>Examples:
507 * <blockquote><pre>
508 * parseLong("0", 10) returns 0L
509 * parseLong("473", 10) returns 473L
510 * parseLong("+42", 10) returns 42L
511 * parseLong("-0", 10) returns 0L
512 * parseLong("-FF", 16) returns -255L
513 * parseLong("1100110", 2) returns 102L
514 * parseLong("99", 8) throws a NumberFormatException
515 * parseLong("Hazelnut", 10) throws a NumberFormatException
516 * parseLong("Hazelnut", 36) returns 1356099454469L
517 * </pre></blockquote>
518 *
519 * @param s the {@code String} containing the
520 * {@code long} representation to be parsed.
521 * @param radix the radix to be used while parsing {@code s}.
522 * @return the {@code long} represented by the string argument in
523 * the specified radix.
524 * @throws NumberFormatException if the string does not contain a
525 * parsable {@code long}.
526 */
527 public static long parseLong(String s, int radix)
528 throws NumberFormatException {
529 if (s == null) {
530 throw new NumberFormatException("Cannot parse null string");
531 }
532
533 if (radix < Character.MIN_RADIX) {
534 throw new NumberFormatException(String.format(
535 "radix %s less than Character.MIN_RADIX", radix));
536 }
537
538 if (radix > Character.MAX_RADIX) {
539 throw new NumberFormatException(String.format(
540 "radix %s greater than Character.MAX_RADIX", radix));
541 }
542
543 int len = s.length();
544 if (len == 0) {
545 throw NumberFormatException.forInputString("", radix);
546 }
547 int digit = ~0xFF;
548 int i = 0;
549 char firstChar = s.charAt(i++);
550 if (firstChar != '-' && firstChar != '+') {
551 digit = digit(firstChar, radix);
552 }
553 if (digit >= 0 || digit == ~0xFF && len > 1) {
554 long limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
555 long multmin = limit / radix;
556 long result = -(digit & 0xFF);
557 boolean inRange = true;
558 /* Accumulating negatively avoids surprises near MAX_VALUE */
559 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
560 && (inRange = result > multmin
561 || result == multmin && digit <= (int) (radix * multmin - limit))) {
562 result = radix * result - digit;
563 }
564 if (inRange && i == len && digit >= 0) {
565 return firstChar != '-' ? -result : result;
566 }
567 }
568 throw NumberFormatException.forInputString(s, radix);
569 }
570
571 /**
572 * Parses the {@link CharSequence} argument as a signed {@code long} in
573 * the specified {@code radix}, beginning at the specified
574 * {@code beginIndex} and extending to {@code endIndex - 1}.
575 *
576 * <p>The method does not take steps to guard against the
577 * {@code CharSequence} being mutated while parsing.
578 *
579 * @param s the {@code CharSequence} containing the {@code long}
580 * representation to be parsed
581 * @param beginIndex the beginning index, inclusive.
582 * @param endIndex the ending index, exclusive.
583 * @param radix the radix to be used while parsing {@code s}.
584 * @return the signed {@code long} represented by the subsequence in
585 * the specified radix.
586 * @throws NullPointerException if {@code s} is null.
587 * @throws IndexOutOfBoundsException if {@code beginIndex} is
588 * negative, or if {@code beginIndex} is greater than
589 * {@code endIndex} or if {@code endIndex} is greater than
590 * {@code s.length()}.
591 * @throws NumberFormatException if the {@code CharSequence} does not
592 * contain a parsable {@code long} in the specified
593 * {@code radix}, or if {@code radix} is either smaller than
594 * {@link java.lang.Character#MIN_RADIX} or larger than
595 * {@link java.lang.Character#MAX_RADIX}.
596 * @since 9
597 */
598 public static long parseLong(CharSequence s, int beginIndex, int endIndex, int radix)
599 throws NumberFormatException {
600 Objects.requireNonNull(s);
601 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
602
603 if (radix < Character.MIN_RADIX) {
604 throw new NumberFormatException(String.format(
605 "radix %s less than Character.MIN_RADIX", radix));
606 }
607
608 if (radix > Character.MAX_RADIX) {
609 throw new NumberFormatException(String.format(
610 "radix %s greater than Character.MAX_RADIX", radix));
611 }
612
613 /*
614 * While s can be concurrently modified, it is ensured that each
615 * of its characters is read at most once, from lower to higher indices.
616 * This is obtained by reading them using the pattern s.charAt(i++),
617 * and by not updating i anywhere else.
618 */
619 if (beginIndex == endIndex) {
620 throw NumberFormatException.forInputString("", radix);
621 }
622 int digit = ~0xFF; // ~0xFF means firstChar char is sign
623 int i = beginIndex;
624 char firstChar = s.charAt(i++);
625 if (firstChar != '-' && firstChar != '+') {
626 digit = digit(firstChar, radix);
627 }
628 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
629 long limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
630 long multmin = limit / radix;
631 long result = -(digit & 0xFF);
632 boolean inRange = true;
633 /* Accumulating negatively avoids surprises near MAX_VALUE */
634 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
635 && (inRange = result > multmin
636 || result == multmin && digit <= (int) (radix * multmin - limit))) {
637 result = radix * result - digit;
638 }
639 if (inRange && i == endIndex && digit >= 0) {
640 return firstChar != '-' ? -result : result;
641 }
642 }
643 throw NumberFormatException.forCharSequence(s, beginIndex,
644 endIndex, i - (digit < -1 ? 0 : 1));
645 }
646
647 /**
648 * Parses the string argument as a signed decimal {@code long}.
649 * The characters in the string must all be decimal digits, except
650 * that the first character may be an ASCII minus sign {@code '-'}
651 * ({@code \u005Cu002D'}) to indicate a negative value or an
652 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
653 * indicate a positive value. The resulting {@code long} value is
654 * returned, exactly as if the argument and the radix {@code 10}
655 * were given as arguments to the {@link
656 * #parseLong(java.lang.String, int)} method.
657 *
658 * <p>Note that neither the character {@code L}
659 * ({@code '\u005Cu004C'}) nor {@code l}
660 * ({@code '\u005Cu006C'}) is permitted to appear at the end
661 * of the string as a type indicator, as would be permitted in
662 * Java programming language source code.
663 *
664 * @param s a {@code String} containing the {@code long}
665 * representation to be parsed
666 * @return the {@code long} represented by the argument in
667 * decimal.
668 * @throws NumberFormatException if the string does not contain a
669 * parsable {@code long}.
670 */
671 public static long parseLong(String s) throws NumberFormatException {
672 return parseLong(s, 10);
673 }
674
675 /**
676 * Parses the string argument as an unsigned {@code long} in the
677 * radix specified by the second argument. An unsigned integer
678 * maps the values usually associated with negative numbers to
679 * positive numbers larger than {@code MAX_VALUE}.
680 *
681 * The characters in the string must all be digits of the
682 * specified radix (as determined by whether {@link
683 * java.lang.Character#digit(char, int)} returns a nonnegative
684 * value), except that the first character may be an ASCII plus
685 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
686 * integer value is returned.
687 *
688 * <p>An exception of type {@code NumberFormatException} is
689 * thrown if any of the following situations occurs:
690 * <ul>
691 * <li>The first argument is {@code null} or is a string of
692 * length zero.
693 *
694 * <li>The radix is either smaller than
695 * {@link java.lang.Character#MIN_RADIX} or
696 * larger than {@link java.lang.Character#MAX_RADIX}.
697 *
698 * <li>Any character of the string is not a digit of the specified
699 * radix, except that the first character may be a plus sign
700 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
701 * string is longer than length 1.
702 *
703 * <li>The value represented by the string is larger than the
704 * largest unsigned {@code long}, 2<sup>64</sup>-1.
705 *
706 * </ul>
707 *
708 *
709 * @param s the {@code String} containing the unsigned integer
710 * representation to be parsed
711 * @param radix the radix to be used while parsing {@code s}.
712 * @return the unsigned {@code long} represented by the string
713 * argument in the specified radix.
714 * @throws NumberFormatException if the {@code String}
715 * does not contain a parsable {@code long}.
716 * @since 1.8
717 */
718 public static long parseUnsignedLong(String s, int radix)
719 throws NumberFormatException {
720 if (s == null) {
721 throw new NumberFormatException("Cannot parse null string");
722 }
723
724 if (radix < Character.MIN_RADIX) {
725 throw new NumberFormatException(String.format(
726 "radix %s less than Character.MIN_RADIX", radix));
727 }
728
729 if (radix > Character.MAX_RADIX) {
730 throw new NumberFormatException(String.format(
731 "radix %s greater than Character.MAX_RADIX", radix));
732 }
733
734 int len = s.length();
735 if (len == 0) {
736 throw NumberFormatException.forInputString(s, radix);
737 }
738 int i = 0;
739 char firstChar = s.charAt(i++);
740 if (firstChar == '-') {
741 throw new NumberFormatException(String.format(
742 "Illegal leading minus sign on unsigned string %s.", s));
743 }
744 int digit = ~0xFF;
745 if (firstChar != '+') {
746 digit = digit(firstChar, radix);
747 }
748 if (digit >= 0 || digit == ~0xFF && len > 1) {
749 long multmax = divideUnsigned(-1L, radix); // -1L is max unsigned long
750 long result = digit & 0xFF;
751 boolean inRange = true;
752 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
753 && (inRange = compareUnsigned(result, multmax) < 0
754 || result == multmax && digit < (int) (-radix * multmax))) {
755 result = radix * result + digit;
756 }
757 if (inRange && i == len && digit >= 0) {
758 return result;
759 }
760 }
761 if (digit < 0) {
762 throw NumberFormatException.forInputString(s, radix);
763 }
764 throw new NumberFormatException(String.format(
765 "String value %s exceeds range of unsigned long.", s));
766 }
767
768 /**
769 * Parses the {@link CharSequence} argument as an unsigned {@code long} in
770 * the specified {@code radix}, beginning at the specified
771 * {@code beginIndex} and extending to {@code endIndex - 1}.
772 *
773 * <p>The method does not take steps to guard against the
774 * {@code CharSequence} being mutated while parsing.
775 *
776 * @param s the {@code CharSequence} containing the unsigned
777 * {@code long} representation to be parsed
778 * @param beginIndex the beginning index, inclusive.
779 * @param endIndex the ending index, exclusive.
780 * @param radix the radix to be used while parsing {@code s}.
781 * @return the unsigned {@code long} represented by the subsequence in
782 * the specified radix.
783 * @throws NullPointerException if {@code s} is null.
784 * @throws IndexOutOfBoundsException if {@code beginIndex} is
785 * negative, or if {@code beginIndex} is greater than
786 * {@code endIndex} or if {@code endIndex} is greater than
787 * {@code s.length()}.
788 * @throws NumberFormatException if the {@code CharSequence} does not
789 * contain a parsable unsigned {@code long} in the specified
790 * {@code radix}, or if {@code radix} is either smaller than
791 * {@link java.lang.Character#MIN_RADIX} or larger than
792 * {@link java.lang.Character#MAX_RADIX}.
793 * @since 9
794 */
795 public static long parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix)
796 throws NumberFormatException {
797 Objects.requireNonNull(s);
798 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
799
800 if (radix < Character.MIN_RADIX) {
801 throw new NumberFormatException(String.format(
802 "radix %s less than Character.MIN_RADIX", radix));
803 }
804
805 if (radix > Character.MAX_RADIX) {
806 throw new NumberFormatException(String.format(
807 "radix %s greater than Character.MAX_RADIX", radix));
808 }
809
810 /*
811 * While s can be concurrently modified, it is ensured that each
812 * of its characters is read at most once, from lower to higher indices.
813 * This is obtained by reading them using the pattern s.charAt(i++),
814 * and by not updating i anywhere else.
815 */
816 if (beginIndex == endIndex) {
817 throw NumberFormatException.forInputString("", radix);
818 }
819 int i = beginIndex;
820 char firstChar = s.charAt(i++);
821 if (firstChar == '-') {
822 throw new NumberFormatException(
823 "Illegal leading minus sign on unsigned string " + s + ".");
824 }
825 int digit = ~0xFF;
826 if (firstChar != '+') {
827 digit = digit(firstChar, radix);
828 }
829 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
830 long multmax = divideUnsigned(-1L, radix); // -1L is max unsigned long
831 long result = digit & 0xFF;
832 boolean inRange = true;
833 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
834 && (inRange = compareUnsigned(result, multmax) < 0
835 || result == multmax && digit < (int) (-radix * multmax))) {
836 result = radix * result + digit;
837 }
838 if (inRange && i == endIndex && digit >= 0) {
839 return result;
840 }
841 }
842 if (digit < 0) {
843 throw NumberFormatException.forCharSequence(s, beginIndex,
844 endIndex, i - (digit < -1 ? 0 : 1));
845 }
846 throw new NumberFormatException(String.format(
847 "String value %s exceeds range of unsigned long.", s));
848 }
849
850 /**
851 * Parses the string argument as an unsigned decimal {@code long}. The
852 * characters in the string must all be decimal digits, except
853 * that the first character may be an ASCII plus sign {@code
854 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
855 * is returned, exactly as if the argument and the radix 10 were
856 * given as arguments to the {@link
857 * #parseUnsignedLong(java.lang.String, int)} method.
858 *
859 * @param s a {@code String} containing the unsigned {@code long}
860 * representation to be parsed
861 * @return the unsigned {@code long} value represented by the decimal string argument
862 * @throws NumberFormatException if the string does not contain a
863 * parsable unsigned integer.
864 * @since 1.8
865 */
866 public static long parseUnsignedLong(String s) throws NumberFormatException {
867 return parseUnsignedLong(s, 10);
868 }
869
870 /**
871 * Returns a {@code Long} object holding the value
872 * extracted from the specified {@code String} when parsed
873 * with the radix given by the second argument. The first
874 * argument is interpreted as representing a signed
875 * {@code long} in the radix specified by the second
876 * argument, exactly as if the arguments were given to the {@link
877 * #parseLong(java.lang.String, int)} method. The result is a
878 * {@code Long} object that represents the {@code long}
879 * value specified by the string.
880 *
881 * <p>In other words, this method returns a {@code Long} object equal
882 * to the value of:
883 *
884 * <blockquote>
885 * {@code Long.valueOf(Long.parseLong(s, radix))}
886 * </blockquote>
887 *
888 * @param s the string to be parsed
889 * @param radix the radix to be used in interpreting {@code s}
890 * @return a {@code Long} object holding the value
891 * represented by the string argument in the specified
892 * radix.
893 * @throws NumberFormatException If the {@code String} does not
894 * contain a parsable {@code long}.
895 */
896 public static Long valueOf(String s, int radix) throws NumberFormatException {
897 return Long.valueOf(parseLong(s, radix));
898 }
899
900 /**
901 * Returns a {@code Long} object holding the value
902 * of the specified {@code String}. The argument is
903 * interpreted as representing a signed decimal {@code long},
904 * exactly as if the argument were given to the {@link
905 * #parseLong(java.lang.String)} method. The result is a
906 * {@code Long} object that represents the integer value
907 * specified by the string.
908 *
909 * <p>In other words, this method returns a {@code Long} object
910 * equal to the value of:
911 *
912 * <blockquote>
913 * {@code Long.valueOf(Long.parseLong(s))}
914 * </blockquote>
915 *
916 * @param s the string to be parsed.
917 * @return a {@code Long} object holding the value
918 * represented by the string argument.
919 * @throws NumberFormatException If the string cannot be parsed
920 * as a {@code long}.
921 */
922 public static Long valueOf(String s) throws NumberFormatException
923 {
924 return Long.valueOf(parseLong(s, 10));
925 }
926
927 @AOTSafeClassInitializer
928 private static final class LongCache {
929 private LongCache() {}
930
931 @Stable
932 static final Long[] cache;
933 static Long[] archivedCache;
934
935 static {
936 int size = -(-128) + 127 + 1;
937
938 // Load and use the archived cache if it exists
939 CDS.initializeFromArchive(LongCache.class);
940 if (archivedCache == null) {
941 Long[] c = new Long[size];
942 long value = -128;
943 for(int i = 0; i < size; i++) {
944 c[i] = new Long(value++);
945 }
946 archivedCache = c;
947 }
948 cache = archivedCache;
949 assert cache.length == size;
950 }
951 }
952
953 /**
954 * Returns a {@code Long} instance representing the specified
955 * {@code long} value.
956 * <div class="preview-block">
957 * <div class="preview-comment">
958 * <p>
959 * - When preview features are NOT enabled, {@code Long} is an identity class.
960 * If a new {@code Long} instance is not required, this method
961 * should generally be used in preference to the constructor
962 * {@link #Long(long)}, as this method is likely to yield
963 * significantly better space and time performance by caching
964 * frequently requested values.
965 * This method will always cache values in the range -128 to 127,
966 * inclusive, and may cache other values outside of this range.
967 * </p>
968 * <p>
969 * - When preview features are enabled, {@code Long} is a {@linkplain Class#isValue value class}.
970 * The {@code valueOf} behavior is the same as invoking the constructor,
971 * whether cached or not.
972 * </p>
973 * </div>
974 * </div>
975 *
976 * @param l a long value.
977 * @return a {@code Long} instance representing {@code l}.
978 * @since 1.5
979 */
980 @IntrinsicCandidate
981 @DeserializeConstructor
982 public static Long valueOf(long l) {
983 if (!PreviewFeatures.isEnabled()) {
984 if (l >= -128 && l <= 127) { // will cache
985 final int offset = 128;
986 return LongCache.cache[(int) l + offset];
987 }
988 }
989 return new Long(l);
990 }
991
992 /**
993 * Decodes a {@code String} into a {@code Long}.
994 * Accepts decimal, hexadecimal, and octal numbers given by the
995 * following grammar:
996 *
997 * <blockquote>
998 * <dl>
999 * <dt><i>DecodableString:</i>
1000 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1001 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1002 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1003 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1004 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1005 *
1006 * <dt><i>Sign:</i>
1007 * <dd>{@code -}
1008 * <dd>{@code +}
1009 * </dl>
1010 * </blockquote>
1011 *
1012 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1013 * are as defined in section {@jls 3.10.1} of
1014 * <cite>The Java Language Specification</cite>,
1015 * except that underscores are not accepted between digits.
1016 *
1017 * <p>The sequence of characters following an optional
1018 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1019 * "{@code #}", or leading zero) is parsed as by the {@code
1020 * Long.parseLong} method with the indicated radix (10, 16, or 8).
1021 * This sequence of characters must represent a positive value or
1022 * a {@link NumberFormatException} will be thrown. The result is
1023 * negated if first character of the specified {@code String} is
1024 * the minus sign. No whitespace characters are permitted in the
1025 * {@code String}.
1026 *
1027 * @param nm the {@code String} to decode.
1028 * @return a {@code Long} object holding the {@code long}
1029 * value represented by {@code nm}
1030 * @throws NumberFormatException if the {@code String} does not
1031 * contain a parsable {@code long}.
1032 * @see java.lang.Long#parseLong(String, int)
1033 * @since 1.2
1034 */
1035 public static Long decode(String nm) throws NumberFormatException {
1036 int radix = 10;
1037 int index = 0;
1038 boolean negative = false;
1039 long result;
1040
1041 if (nm.isEmpty())
1042 throw new NumberFormatException("Zero length string");
1043 char firstChar = nm.charAt(0);
1044 // Handle sign, if present
1045 if (firstChar == '-') {
1046 negative = true;
1047 index++;
1048 } else if (firstChar == '+')
1049 index++;
1050
1051 // Handle radix specifier, if present
1052 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1053 index += 2;
1054 radix = 16;
1055 }
1056 else if (nm.startsWith("#", index)) {
1057 index ++;
1058 radix = 16;
1059 }
1060 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1061 index ++;
1062 radix = 8;
1063 }
1064
1065 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1066 throw new NumberFormatException("Sign character in wrong position");
1067
1068 try {
1069 result = parseLong(nm, index, nm.length(), radix);
1070 result = negative ? -result : result;
1071 } catch (NumberFormatException e) {
1072 // If number is Long.MIN_VALUE, we'll end up here. The next line
1073 // handles this case, and causes any genuine format error to be
1074 // rethrown.
1075 String constant = negative ? ("-" + nm.substring(index))
1076 : nm.substring(index);
1077 result = parseLong(constant, radix);
1078 }
1079 return result;
1080 }
1081
1082 /**
1083 * The value of the {@code Long}.
1084 *
1085 * @serial
1086 */
1087 private final long value;
1088
1089 /**
1090 * Constructs a newly allocated {@code Long} object that
1091 * represents the specified {@code long} argument.
1092 *
1093 * @param value the value to be represented by the
1094 * {@code Long} object.
1095 *
1096 * @deprecated
1097 * It is rarely appropriate to use this constructor. The static factory
1098 * {@link #valueOf(long)} is generally a better choice, as it is
1099 * likely to yield significantly better space and time performance.
1100 */
1101 @Deprecated(since="9")
1102 public Long(long value) {
1103 this.value = value;
1104 }
1105
1106 /**
1107 * Constructs a newly allocated {@code Long} object that
1108 * represents the {@code long} value indicated by the
1109 * {@code String} parameter. The string is converted to a
1110 * {@code long} value in exactly the manner used by the
1111 * {@code parseLong} method for radix 10.
1112 *
1113 * @param s the {@code String} to be converted to a
1114 * {@code Long}.
1115 * @throws NumberFormatException if the {@code String} does not
1116 * contain a parsable {@code long}.
1117 *
1118 * @deprecated
1119 * It is rarely appropriate to use this constructor.
1120 * Use {@link #parseLong(String)} to convert a string to a
1121 * {@code long} primitive, or use {@link #valueOf(String)}
1122 * to convert a string to a {@code Long} object.
1123 */
1124 @Deprecated(since="9")
1125 public Long(String s) throws NumberFormatException {
1126 this.value = parseLong(s, 10);
1127 }
1128
1129 /**
1130 * Returns the value of this {@code Long} as a {@code byte} after
1131 * a narrowing primitive conversion.
1132 * @jls 5.1.3 Narrowing Primitive Conversion
1133 */
1134 public byte byteValue() {
1135 return (byte)value;
1136 }
1137
1138 /**
1139 * Returns the value of this {@code Long} as a {@code short} after
1140 * a narrowing primitive conversion.
1141 * @jls 5.1.3 Narrowing Primitive Conversion
1142 */
1143 public short shortValue() {
1144 return (short)value;
1145 }
1146
1147 /**
1148 * Returns the value of this {@code Long} as an {@code int} after
1149 * a narrowing primitive conversion.
1150 * @jls 5.1.3 Narrowing Primitive Conversion
1151 */
1152 public int intValue() {
1153 return (int)value;
1154 }
1155
1156 /**
1157 * Returns the value of this {@code Long} as a
1158 * {@code long} value.
1159 */
1160 @IntrinsicCandidate
1161 public long longValue() {
1162 return value;
1163 }
1164
1165 /**
1166 * Returns the value of this {@code Long} as a {@code float} after
1167 * a widening primitive conversion.
1168 * @jls 5.1.2 Widening Primitive Conversion
1169 */
1170 public float floatValue() {
1171 return (float)value;
1172 }
1173
1174 /**
1175 * Returns the value of this {@code Long} as a {@code double}
1176 * after a widening primitive conversion.
1177 * @jls 5.1.2 Widening Primitive Conversion
1178 */
1179 public double doubleValue() {
1180 return (double)value;
1181 }
1182
1183 /**
1184 * Returns a {@code String} object representing this
1185 * {@code Long}'s value. The value is converted to signed
1186 * decimal representation and returned as a string, exactly as if
1187 * the {@code long} value were given as an argument to the
1188 * {@link java.lang.Long#toString(long)} method.
1189 *
1190 * @return a string representation of the value of this object in
1191 * base 10.
1192 */
1193 public String toString() {
1194 return toString(value);
1195 }
1196
1197 /**
1198 * Returns a hash code for this {@code Long}. The result is
1199 * the exclusive OR of the two halves of the primitive
1200 * {@code long} value held by this {@code Long}
1201 * object. That is, the hashcode is the value of the expression:
1202 *
1203 * <blockquote>
1204 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1205 * </blockquote>
1206 *
1207 * @return a hash code value for this object.
1208 */
1209 @Override
1210 public int hashCode() {
1211 return Long.hashCode(value);
1212 }
1213
1214 /**
1215 * Returns a hash code for a {@code long} value; compatible with
1216 * {@code Long.hashCode()}.
1217 *
1218 * @param value the value to hash
1219 * @return a hash code value for a {@code long} value.
1220 * @since 1.8
1221 */
1222 public static int hashCode(long value) {
1223 return (int)(value ^ (value >>> 32));
1224 }
1225
1226 /**
1227 * Compares this object to the specified object. The result is
1228 * {@code true} if and only if the argument is not
1229 * {@code null} and is a {@code Long} object that
1230 * contains the same {@code long} value as this object.
1231 *
1232 * @param obj the object to compare with.
1233 * @return {@code true} if the objects are the same;
1234 * {@code false} otherwise.
1235 */
1236 public boolean equals(Object obj) {
1237 if (obj instanceof Long ell) {
1238 return value == ell.longValue();
1239 }
1240 return false;
1241 }
1242
1243 /**
1244 * Determines the {@code long} value of the system property
1245 * with the specified name.
1246 *
1247 * <p>The first argument is treated as the name of a system
1248 * property. System properties are accessible through the {@link
1249 * java.lang.System#getProperty(java.lang.String)} method. The
1250 * string value of this property is then interpreted as a {@code
1251 * long} value using the grammar supported by {@link Long#decode decode}
1252 * and a {@code Long} object representing this value is returned.
1253 *
1254 * <p>If there is no property with the specified name, if the
1255 * specified name is empty or {@code null}, or if the property
1256 * does not have the correct numeric format, then {@code null} is
1257 * returned.
1258 *
1259 * <p>In other words, this method returns a {@code Long} object
1260 * equal to the value of:
1261 *
1262 * <blockquote>
1263 * {@code getLong(nm, null)}
1264 * </blockquote>
1265 *
1266 * @param nm property name.
1267 * @return the {@code Long} value of the property.
1268 * @see java.lang.System#getProperty(java.lang.String)
1269 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1270 */
1271 public static Long getLong(String nm) {
1272 return getLong(nm, null);
1273 }
1274
1275 /**
1276 * Determines the {@code long} value of the system property
1277 * with the specified name.
1278 *
1279 * <p>The first argument is treated as the name of a system
1280 * property. System properties are accessible through the {@link
1281 * java.lang.System#getProperty(java.lang.String)} method. The
1282 * string value of this property is then interpreted as a {@code
1283 * long} value using the grammar supported by {@link Long#decode decode}
1284 * and a {@code Long} object representing this value is returned.
1285 *
1286 * <p>The second argument is the default value. A {@code Long} object
1287 * that represents the value of the second argument is returned if there
1288 * is no property of the specified name, if the property does not have
1289 * the correct numeric format, or if the specified name is empty or null.
1290 *
1291 * <p>In other words, this method returns a {@code Long} object equal
1292 * to the value of:
1293 *
1294 * <blockquote>
1295 * {@code getLong(nm, Long.valueOf(val))}
1296 * </blockquote>
1297 *
1298 * but in practice it may be implemented in a manner such as:
1299 *
1300 * <blockquote><pre>
1301 * Long result = getLong(nm, null);
1302 * return (result == null) ? Long.valueOf(val) : result;
1303 * </pre></blockquote>
1304 *
1305 * to avoid the unnecessary allocation of a {@code Long} object when
1306 * the default value is not needed.
1307 *
1308 * @param nm property name.
1309 * @param val default value.
1310 * @return the {@code Long} value of the property.
1311 * @see java.lang.System#getProperty(java.lang.String)
1312 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1313 */
1314 public static Long getLong(String nm, long val) {
1315 Long result = Long.getLong(nm, null);
1316 return (result == null) ? Long.valueOf(val) : result;
1317 }
1318
1319 /**
1320 * Returns the {@code long} value of the system property with
1321 * the specified name. The first argument is treated as the name
1322 * of a system property. System properties are accessible through
1323 * the {@link java.lang.System#getProperty(java.lang.String)}
1324 * method. The string value of this property is then interpreted
1325 * as a {@code long} value, as per the
1326 * {@link Long#decode decode} method, and a {@code Long} object
1327 * representing this value is returned; in summary:
1328 *
1329 * <ul>
1330 * <li>If the property value begins with the two ASCII characters
1331 * {@code 0x} or the ASCII character {@code #}, not followed by
1332 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1333 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1334 * with radix 16.
1335 * <li>If the property value begins with the ASCII character
1336 * {@code 0} followed by another character, it is parsed as
1337 * an octal integer exactly as by the method {@link
1338 * #valueOf(java.lang.String, int)} with radix 8.
1339 * <li>Otherwise the property value is parsed as a decimal
1340 * integer exactly as by the method
1341 * {@link #valueOf(java.lang.String, int)} with radix 10.
1342 * </ul>
1343 *
1344 * <p>Note that, in every case, neither {@code L}
1345 * ({@code '\u005Cu004C'}) nor {@code l}
1346 * ({@code '\u005Cu006C'}) is permitted to appear at the end
1347 * of the property value as a type indicator, as would be
1348 * permitted in Java programming language source code.
1349 *
1350 * <p>The second argument is the default value. The default value is
1351 * returned if there is no property of the specified name, if the
1352 * property does not have the correct numeric format, or if the
1353 * specified name is empty or {@code null}.
1354 *
1355 * @param nm property name.
1356 * @param val default value.
1357 * @return the {@code Long} value of the property.
1358 * @see System#getProperty(java.lang.String)
1359 * @see System#getProperty(java.lang.String, java.lang.String)
1360 */
1361 public static Long getLong(String nm, Long val) {
1362 String v = nm != null && !nm.isEmpty() ? System.getProperty(nm) : null;
1363 if (v != null) {
1364 try {
1365 return Long.decode(v);
1366 } catch (NumberFormatException e) {
1367 }
1368 }
1369 return val;
1370 }
1371
1372 /**
1373 * Compares two {@code Long} objects numerically.
1374 *
1375 * @param anotherLong the {@code Long} to be compared.
1376 * @return the value {@code 0} if this {@code Long} is
1377 * equal to the argument {@code Long}; a value less than
1378 * {@code 0} if this {@code Long} is numerically less
1379 * than the argument {@code Long}; and a value greater
1380 * than {@code 0} if this {@code Long} is numerically
1381 * greater than the argument {@code Long} (signed
1382 * comparison).
1383 * @since 1.2
1384 */
1385 public int compareTo(Long anotherLong) {
1386 return compare(this.value, anotherLong.value);
1387 }
1388
1389 /**
1390 * Compares two {@code long} values numerically.
1391 * The value returned is identical to what would be returned by:
1392 * <pre>
1393 * Long.valueOf(x).compareTo(Long.valueOf(y))
1394 * </pre>
1395 *
1396 * @param x the first {@code long} to compare
1397 * @param y the second {@code long} to compare
1398 * @return the value {@code 0} if {@code x == y};
1399 * a value less than {@code 0} if {@code x < y}; and
1400 * a value greater than {@code 0} if {@code x > y}
1401 * @since 1.7
1402 */
1403 public static int compare(long x, long y) {
1404 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1405 }
1406
1407 /**
1408 * Compares two {@code long} values numerically treating the values
1409 * as unsigned.
1410 *
1411 * @param x the first {@code long} to compare
1412 * @param y the second {@code long} to compare
1413 * @return the value {@code 0} if {@code x == y}; a value less
1414 * than {@code 0} if {@code x < y} as unsigned values; and
1415 * a value greater than {@code 0} if {@code x > y} as
1416 * unsigned values
1417 * @since 1.8
1418 */
1419 @IntrinsicCandidate
1420 public static int compareUnsigned(long x, long y) {
1421 return compare(x + MIN_VALUE, y + MIN_VALUE);
1422 }
1423
1424
1425 /**
1426 * Returns the unsigned quotient of dividing the first argument by
1427 * the second where each argument and the result is interpreted as
1428 * an unsigned value.
1429 *
1430 * <p>Note that in two's complement arithmetic, the three other
1431 * basic arithmetic operations of add, subtract, and multiply are
1432 * bit-wise identical if the two operands are regarded as both
1433 * being signed or both being unsigned. Therefore separate {@code
1434 * addUnsigned}, etc. methods are not provided.
1435 *
1436 * @param dividend the value to be divided
1437 * @param divisor the value doing the dividing
1438 * @return the unsigned quotient of the first argument divided by
1439 * the second argument
1440 * @see #remainderUnsigned
1441 * @since 1.8
1442 */
1443 @IntrinsicCandidate
1444 public static long divideUnsigned(long dividend, long divisor) {
1445 /* See Hacker's Delight (2nd ed), section 9.3 */
1446 if (divisor >= 0) {
1447 final long q = (dividend >>> 1) / divisor << 1;
1448 final long r = dividend - q * divisor;
1449 return q + ((r | ~(r - divisor)) >>> (Long.SIZE - 1));
1450 }
1451 return (dividend & ~(dividend - divisor)) >>> (Long.SIZE - 1);
1452 }
1453
1454 /**
1455 * Returns the unsigned remainder from dividing the first argument
1456 * by the second where each argument and the result is interpreted
1457 * as an unsigned value.
1458 *
1459 * @param dividend the value to be divided
1460 * @param divisor the value doing the dividing
1461 * @return the unsigned remainder of the first argument divided by
1462 * the second argument
1463 * @see #divideUnsigned
1464 * @since 1.8
1465 */
1466 @IntrinsicCandidate
1467 public static long remainderUnsigned(long dividend, long divisor) {
1468 /* See Hacker's Delight (2nd ed), section 9.3 */
1469 if (divisor >= 0) {
1470 final long q = (dividend >>> 1) / divisor << 1;
1471 final long r = dividend - q * divisor;
1472 /*
1473 * Here, 0 <= r < 2 * divisor
1474 * (1) When 0 <= r < divisor, the remainder is simply r.
1475 * (2) Otherwise the remainder is r - divisor.
1476 *
1477 * In case (1), r - divisor < 0. Applying ~ produces a long with
1478 * sign bit 0, so >> produces 0. The returned value is thus r.
1479 *
1480 * In case (2), a similar reasoning shows that >> produces -1,
1481 * so the returned value is r - divisor.
1482 */
1483 return r - ((~(r - divisor) >> (Long.SIZE - 1)) & divisor);
1484 }
1485 /*
1486 * (1) When dividend >= 0, the remainder is dividend.
1487 * (2) Otherwise
1488 * (2.1) When dividend < divisor, the remainder is dividend.
1489 * (2.2) Otherwise the remainder is dividend - divisor
1490 *
1491 * A reasoning similar to the above shows that the returned value
1492 * is as expected.
1493 */
1494 return dividend - (((dividend & ~(dividend - divisor)) >> (Long.SIZE - 1)) & divisor);
1495 }
1496
1497 // Bit Twiddling
1498
1499 /**
1500 * The number of bits used to represent a {@code long} value in two's
1501 * complement binary form.
1502 *
1503 * @since 1.5
1504 */
1505 @Native public static final int SIZE = 64;
1506
1507 /**
1508 * The number of bytes used to represent a {@code long} value in two's
1509 * complement binary form.
1510 *
1511 * @since 1.8
1512 */
1513 public static final int BYTES = SIZE / Byte.SIZE;
1514
1515 /**
1516 * Returns a {@code long} value with at most a single one-bit, in the
1517 * position of the highest-order ("leftmost") one-bit in the specified
1518 * {@code long} value. Returns zero if the specified value has no
1519 * one-bits in its two's complement binary representation, that is, if it
1520 * is equal to zero.
1521 *
1522 * @param i the value whose highest one bit is to be computed
1523 * @return a {@code long} value with a single one-bit, in the position
1524 * of the highest-order one-bit in the specified value, or zero if
1525 * the specified value is itself equal to zero.
1526 * @since 1.5
1527 */
1528 public static long highestOneBit(long i) {
1529 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1530 }
1531
1532 /**
1533 * Returns a {@code long} value with at most a single one-bit, in the
1534 * position of the lowest-order ("rightmost") one-bit in the specified
1535 * {@code long} value. Returns zero if the specified value has no
1536 * one-bits in its two's complement binary representation, that is, if it
1537 * is equal to zero.
1538 *
1539 * @param i the value whose lowest one bit is to be computed
1540 * @return a {@code long} value with a single one-bit, in the position
1541 * of the lowest-order one-bit in the specified value, or zero if
1542 * the specified value is itself equal to zero.
1543 * @since 1.5
1544 */
1545 public static long lowestOneBit(long i) {
1546 // HD, Section 2-1
1547 return i & -i;
1548 }
1549
1550 /**
1551 * Returns the number of zero bits preceding the highest-order
1552 * ("leftmost") one-bit in the two's complement binary representation
1553 * of the specified {@code long} value. Returns 64 if the
1554 * specified value has no one-bits in its two's complement representation,
1555 * in other words if it is equal to zero.
1556 *
1557 * <p>Note that this method is closely related to the logarithm base 2.
1558 * For all positive {@code long} values x:
1559 * <ul>
1560 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1561 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1562 * </ul>
1563 *
1564 * @param i the value whose number of leading zeros is to be computed
1565 * @return the number of zero bits preceding the highest-order
1566 * ("leftmost") one-bit in the two's complement binary representation
1567 * of the specified {@code long} value, or 64 if the value
1568 * is equal to zero.
1569 * @since 1.5
1570 */
1571 @IntrinsicCandidate
1572 public static int numberOfLeadingZeros(long i) {
1573 int x = (int)(i >>> 32);
1574 return x == 0 ? 32 + Integer.numberOfLeadingZeros((int)i)
1575 : Integer.numberOfLeadingZeros(x);
1576 }
1577
1578 /**
1579 * Returns the number of zero bits following the lowest-order ("rightmost")
1580 * one-bit in the two's complement binary representation of the specified
1581 * {@code long} value. Returns 64 if the specified value has no
1582 * one-bits in its two's complement representation, in other words if it is
1583 * equal to zero.
1584 *
1585 * @param i the value whose number of trailing zeros is to be computed
1586 * @return the number of zero bits following the lowest-order ("rightmost")
1587 * one-bit in the two's complement binary representation of the
1588 * specified {@code long} value, or 64 if the value is equal
1589 * to zero.
1590 * @since 1.5
1591 */
1592 @IntrinsicCandidate
1593 public static int numberOfTrailingZeros(long i) {
1594 int x = (int)i;
1595 return x == 0 ? 32 + Integer.numberOfTrailingZeros((int)(i >>> 32))
1596 : Integer.numberOfTrailingZeros(x);
1597 }
1598
1599 /**
1600 * Returns the number of one-bits in the two's complement binary
1601 * representation of the specified {@code long} value. This function is
1602 * sometimes referred to as the <i>population count</i>.
1603 *
1604 * @param i the value whose bits are to be counted
1605 * @return the number of one-bits in the two's complement binary
1606 * representation of the specified {@code long} value.
1607 * @since 1.5
1608 */
1609 @IntrinsicCandidate
1610 public static int bitCount(long i) {
1611 // HD, Figure 5-2
1612 i = i - ((i >>> 1) & 0x5555555555555555L);
1613 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1614 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1615 i = i + (i >>> 8);
1616 i = i + (i >>> 16);
1617 i = i + (i >>> 32);
1618 return (int)i & 0x7f;
1619 }
1620
1621 /**
1622 * Returns the value obtained by rotating the two's complement binary
1623 * representation of the specified {@code long} value left by the
1624 * specified number of bits. (Bits shifted out of the left hand, or
1625 * high-order, side reenter on the right, or low-order.)
1626 *
1627 * <p>Note that left rotation with a negative distance is equivalent to
1628 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1629 * distance)}. Note also that rotation by any multiple of 64 is a
1630 * no-op, so all but the last six bits of the rotation distance can be
1631 * ignored, even if the distance is negative: {@code rotateLeft(val,
1632 * distance) == rotateLeft(val, distance & 0x3F)}.
1633 *
1634 * @param i the value whose bits are to be rotated left
1635 * @param distance the number of bit positions to rotate left
1636 * @return the value obtained by rotating the two's complement binary
1637 * representation of the specified {@code long} value left by the
1638 * specified number of bits.
1639 * @since 1.5
1640 */
1641 public static long rotateLeft(long i, int distance) {
1642 return (i << distance) | (i >>> -distance);
1643 }
1644
1645 /**
1646 * Returns the value obtained by rotating the two's complement binary
1647 * representation of the specified {@code long} value right by the
1648 * specified number of bits. (Bits shifted out of the right hand, or
1649 * low-order, side reenter on the left, or high-order.)
1650 *
1651 * <p>Note that right rotation with a negative distance is equivalent to
1652 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1653 * distance)}. Note also that rotation by any multiple of 64 is a
1654 * no-op, so all but the last six bits of the rotation distance can be
1655 * ignored, even if the distance is negative: {@code rotateRight(val,
1656 * distance) == rotateRight(val, distance & 0x3F)}.
1657 *
1658 * @param i the value whose bits are to be rotated right
1659 * @param distance the number of bit positions to rotate right
1660 * @return the value obtained by rotating the two's complement binary
1661 * representation of the specified {@code long} value right by the
1662 * specified number of bits.
1663 * @since 1.5
1664 */
1665 public static long rotateRight(long i, int distance) {
1666 return (i >>> distance) | (i << -distance);
1667 }
1668
1669 /**
1670 * Returns the value obtained by reversing the order of the bits in the
1671 * two's complement binary representation of the specified {@code long}
1672 * value.
1673 *
1674 * @param i the value to be reversed
1675 * @return the value obtained by reversing order of the bits in the
1676 * specified {@code long} value.
1677 * @since 1.5
1678 */
1679 @IntrinsicCandidate
1680 public static long reverse(long i) {
1681 // HD, Figure 7-1
1682 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1683 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1684 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1685
1686 return reverseBytes(i);
1687 }
1688
1689 /**
1690 * Returns the value obtained by compressing the bits of the
1691 * specified {@code long} value, {@code i}, in accordance with
1692 * the specified bit mask.
1693 * <p>
1694 * For each one-bit value {@code mb} of the mask, from least
1695 * significant to most significant, the bit value of {@code i} at
1696 * the same bit location as {@code mb} is assigned to the compressed
1697 * value contiguously starting from the least significant bit location.
1698 * All the upper remaining bits of the compressed value are set
1699 * to zero.
1700 *
1701 * @apiNote
1702 * Consider the simple case of compressing the digits of a hexadecimal
1703 * value:
1704 * {@snippet lang="java" :
1705 * // Compressing drink to food
1706 * compress(0xCAFEBABEL, 0xFF00FFF0L) == 0xCABABL
1707 * }
1708 * Starting from the least significant hexadecimal digit at position 0
1709 * from the right, the mask {@code 0xFF00FFF0} selects hexadecimal digits
1710 * at positions 1, 2, 3, 6 and 7 of {@code 0xCAFEBABE}. The selected digits
1711 * occur in the resulting compressed value contiguously from digit position
1712 * 0 in the same order.
1713 * <p>
1714 * The following identities all return {@code true} and are helpful to
1715 * understand the behaviour of {@code compress}:
1716 * {@snippet lang="java" :
1717 * // Returns 1 if the bit at position n is one
1718 * compress(x, 1L << n) == (x >> n & 1)
1719 *
1720 * // Logical shift right
1721 * compress(x, -1L << n) == x >>> n
1722 *
1723 * // Any bits not covered by the mask are ignored
1724 * compress(x, m) == compress(x & m, m)
1725 *
1726 * // Compressing a value by itself
1727 * compress(m, m) == (m == -1 || m == 0) ? m : (1L << bitCount(m)) - 1
1728 *
1729 * // Expanding then compressing with the same mask
1730 * compress(expand(x, m), m) == x & compress(m, m)
1731 * }
1732 * <p>
1733 * The Sheep And Goats (SAG) operation (see Hacker's Delight, Second Edition, section 7.7)
1734 * can be implemented as follows:
1735 * {@snippet lang="java" :
1736 * long compressLeft(long i, long mask) {
1737 * // This implementation follows the description in Hacker's Delight which
1738 * // is informative. A more optimal implementation is:
1739 * // Long.compress(i, mask) << -Long.bitCount(mask)
1740 * return Long.reverse(
1741 * Long.compress(Long.reverse(i), Long.reverse(mask)));
1742 * }
1743 *
1744 * long sag(long i, long mask) {
1745 * return compressLeft(i, mask) | Long.compress(i, ~mask);
1746 * }
1747 *
1748 * // Separate the sheep from the goats
1749 * sag(0x00000000_CAFEBABEL, 0xFFFFFFFF_FF00FFF0L) == 0x00000000_CABABFEEL
1750 * }
1751 *
1752 * @param i the value whose bits are to be compressed
1753 * @param mask the bit mask
1754 * @return the compressed value
1755 * @see #expand
1756 * @since 19
1757 */
1758 @IntrinsicCandidate
1759 public static long compress(long i, long mask) {
1760 // See Hacker's Delight (2nd ed) section 7.4 Compress, or Generalized Extract
1761
1762 i = i & mask; // Clear irrelevant bits
1763 long maskCount = ~mask << 1; // Count 0's to right
1764
1765 for (int j = 0; j < 6; j++) {
1766 // Parallel prefix
1767 // Mask prefix identifies bits of the mask that have an odd number of 0's to the right
1768 long maskPrefix = parallelSuffix(maskCount);
1769 // Bits to move
1770 long maskMove = maskPrefix & mask;
1771 // Compress mask
1772 mask = (mask ^ maskMove) | (maskMove >>> (1 << j));
1773 // Bits of i to be moved
1774 long t = i & maskMove;
1775 // Compress i
1776 i = (i ^ t) | (t >>> (1 << j));
1777 // Adjust the mask count by identifying bits that have 0 to the right
1778 maskCount = maskCount & ~maskPrefix;
1779 }
1780 return i;
1781 }
1782
1783 /**
1784 * Returns the value obtained by expanding the bits of the
1785 * specified {@code long} value, {@code i}, in accordance with
1786 * the specified bit mask.
1787 * <p>
1788 * For each one-bit value {@code mb} of the mask, from least
1789 * significant to most significant, the next contiguous bit value
1790 * of {@code i} starting at the least significant bit is assigned
1791 * to the expanded value at the same bit location as {@code mb}.
1792 * All other remaining bits of the expanded value are set to zero.
1793 *
1794 * @apiNote
1795 * Consider the simple case of expanding the digits of a hexadecimal
1796 * value:
1797 * {@snippet lang="java" :
1798 * expand(0x0000CABABL, 0xFF00FFF0L) == 0xCA00BAB0L
1799 * }
1800 * Starting from the least significant hexadecimal digit at position 0
1801 * from the right, the mask {@code 0xFF00FFF0} selects the first five
1802 * hexadecimal digits of {@code 0x0000CABAB}. The selected digits occur
1803 * in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.
1804 * <p>
1805 * The following identities all return {@code true} and are helpful to
1806 * understand the behaviour of {@code expand}:
1807 * {@snippet lang="java" :
1808 * // Logically shift right the bit at position 0
1809 * expand(x, 1L << n) == (x & 1) << n
1810 *
1811 * // Logically shift right
1812 * expand(x, -1L << n) == x << n
1813 *
1814 * // Expanding all bits returns the mask
1815 * expand(-1L, m) == m
1816 *
1817 * // Any bits not covered by the mask are ignored
1818 * expand(x, m) == expand(x, m) & m
1819 *
1820 * // Compressing then expanding with the same mask
1821 * expand(compress(x, m), m) == x & m
1822 * }
1823 * <p>
1824 * The select operation for determining the position of the one-bit with
1825 * index {@code n} in a {@code long} value can be implemented as follows:
1826 * {@snippet lang="java" :
1827 * long select(long i, long n) {
1828 * // the one-bit in i (the mask) with index n
1829 * long nthBit = Long.expand(1L << n, i);
1830 * // the bit position of the one-bit with index n
1831 * return Long.numberOfTrailingZeros(nthBit);
1832 * }
1833 *
1834 * // The one-bit with index 0 is at bit position 1
1835 * select(0b10101010_10101010, 0) == 1
1836 * // The one-bit with index 3 is at bit position 7
1837 * select(0b10101010_10101010, 3) == 7
1838 * }
1839 *
1840 * @param i the value whose bits are to be expanded
1841 * @param mask the bit mask
1842 * @return the expanded value
1843 * @see #compress
1844 * @since 19
1845 */
1846 @IntrinsicCandidate
1847 public static long expand(long i, long mask) {
1848 // Save original mask
1849 long originalMask = mask;
1850 // Count 0's to right
1851 long maskCount = ~mask << 1;
1852 long maskPrefix = parallelSuffix(maskCount);
1853 // Bits to move
1854 long maskMove1 = maskPrefix & mask;
1855 // Compress mask
1856 mask = (mask ^ maskMove1) | (maskMove1 >>> (1 << 0));
1857 maskCount = maskCount & ~maskPrefix;
1858
1859 maskPrefix = parallelSuffix(maskCount);
1860 // Bits to move
1861 long maskMove2 = maskPrefix & mask;
1862 // Compress mask
1863 mask = (mask ^ maskMove2) | (maskMove2 >>> (1 << 1));
1864 maskCount = maskCount & ~maskPrefix;
1865
1866 maskPrefix = parallelSuffix(maskCount);
1867 // Bits to move
1868 long maskMove3 = maskPrefix & mask;
1869 // Compress mask
1870 mask = (mask ^ maskMove3) | (maskMove3 >>> (1 << 2));
1871 maskCount = maskCount & ~maskPrefix;
1872
1873 maskPrefix = parallelSuffix(maskCount);
1874 // Bits to move
1875 long maskMove4 = maskPrefix & mask;
1876 // Compress mask
1877 mask = (mask ^ maskMove4) | (maskMove4 >>> (1 << 3));
1878 maskCount = maskCount & ~maskPrefix;
1879
1880 maskPrefix = parallelSuffix(maskCount);
1881 // Bits to move
1882 long maskMove5 = maskPrefix & mask;
1883 // Compress mask
1884 mask = (mask ^ maskMove5) | (maskMove5 >>> (1 << 4));
1885 maskCount = maskCount & ~maskPrefix;
1886
1887 maskPrefix = parallelSuffix(maskCount);
1888 // Bits to move
1889 long maskMove6 = maskPrefix & mask;
1890
1891 long t = i << (1 << 5);
1892 i = (i & ~maskMove6) | (t & maskMove6);
1893 t = i << (1 << 4);
1894 i = (i & ~maskMove5) | (t & maskMove5);
1895 t = i << (1 << 3);
1896 i = (i & ~maskMove4) | (t & maskMove4);
1897 t = i << (1 << 2);
1898 i = (i & ~maskMove3) | (t & maskMove3);
1899 t = i << (1 << 1);
1900 i = (i & ~maskMove2) | (t & maskMove2);
1901 t = i << (1 << 0);
1902 i = (i & ~maskMove1) | (t & maskMove1);
1903
1904 // Clear irrelevant bits
1905 return i & originalMask;
1906 }
1907
1908 @ForceInline
1909 private static long parallelSuffix(long maskCount) {
1910 long maskPrefix = maskCount ^ (maskCount << 1);
1911 maskPrefix = maskPrefix ^ (maskPrefix << 2);
1912 maskPrefix = maskPrefix ^ (maskPrefix << 4);
1913 maskPrefix = maskPrefix ^ (maskPrefix << 8);
1914 maskPrefix = maskPrefix ^ (maskPrefix << 16);
1915 maskPrefix = maskPrefix ^ (maskPrefix << 32);
1916 return maskPrefix;
1917 }
1918
1919 /**
1920 * Returns the signum function of the specified {@code long} value. (The
1921 * return value is -1 if the specified value is negative; 0 if the
1922 * specified value is zero; and 1 if the specified value is positive.)
1923 *
1924 * @param i the value whose signum is to be computed
1925 * @return the signum function of the specified {@code long} value.
1926 * @since 1.5
1927 */
1928 public static int signum(long i) {
1929 // HD, Section 2-7
1930 return (int) ((i >> 63) | (-i >>> 63));
1931 }
1932
1933 /**
1934 * Returns the value obtained by reversing the order of the bytes in the
1935 * two's complement representation of the specified {@code long} value.
1936 *
1937 * @param i the value whose bytes are to be reversed
1938 * @return the value obtained by reversing the bytes in the specified
1939 * {@code long} value.
1940 * @since 1.5
1941 */
1942 @IntrinsicCandidate
1943 public static long reverseBytes(long i) {
1944 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1945 return (i << 48) | ((i & 0xffff0000L) << 16) |
1946 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1947 }
1948
1949 /**
1950 * Adds two {@code long} values together as per the + operator.
1951 *
1952 * @param a the first operand
1953 * @param b the second operand
1954 * @return the sum of {@code a} and {@code b}
1955 * @see java.util.function.BinaryOperator
1956 * @since 1.8
1957 */
1958 public static long sum(long a, long b) {
1959 return a + b;
1960 }
1961
1962 /**
1963 * Returns the greater of two {@code long} values
1964 * as if by calling {@link Math#max(long, long) Math.max}.
1965 *
1966 * @param a the first operand
1967 * @param b the second operand
1968 * @return the greater of {@code a} and {@code b}
1969 * @see java.util.function.BinaryOperator
1970 * @since 1.8
1971 */
1972 public static long max(long a, long b) {
1973 return Math.max(a, b);
1974 }
1975
1976 /**
1977 * Returns the smaller of two {@code long} values
1978 * as if by calling {@link Math#min(long, long) Math.min}.
1979 *
1980 * @param a the first operand
1981 * @param b the second operand
1982 * @return the smaller of {@code a} and {@code b}
1983 * @see java.util.function.BinaryOperator
1984 * @since 1.8
1985 */
1986 public static long min(long a, long b) {
1987 return Math.min(a, b);
1988 }
1989
1990 /**
1991 * Returns an {@link Optional} containing the nominal descriptor for this
1992 * instance, which is the instance itself.
1993 *
1994 * @return an {@link Optional} describing the {@linkplain Long} instance
1995 * @since 12
1996 */
1997 @Override
1998 public Optional<Long> describeConstable() {
1999 return Optional.of(this);
2000 }
2001
2002 /**
2003 * Resolves this instance as a {@link ConstantDesc}, the result of which is
2004 * the instance itself.
2005 *
2006 * @param lookup ignored
2007 * @return the {@linkplain Long} instance
2008 * @since 12
2009 */
2010 @Override
2011 public Long resolveConstantDesc(MethodHandles.Lookup lookup) {
2012 return this;
2013 }
2014
2015 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2016 @java.io.Serial
2017 @Native private static final long serialVersionUID = 4290774380558885855L;
2018 }