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 jdk.internal.misc.CDS;
29 import jdk.internal.misc.PreviewFeatures;
30 import jdk.internal.misc.VM;
31 import jdk.internal.util.DecimalDigits;
32 import jdk.internal.value.DeserializeConstructor;
33 import jdk.internal.vm.annotation.ForceInline;
34 import jdk.internal.vm.annotation.IntrinsicCandidate;
35 import jdk.internal.vm.annotation.Stable;
36
37 import java.lang.annotation.Native;
38 import java.lang.constant.Constable;
39 import java.lang.constant.ConstantDesc;
40 import java.lang.invoke.MethodHandles;
41 import java.util.Objects;
42 import java.util.Optional;
43
44 import static java.lang.Character.digit;
45 import static java.lang.String.COMPACT_STRINGS;
46 import static java.lang.String.LATIN1;
47 import static java.lang.String.UTF16;
48
49 /**
50 * The {@code Integer} class is the {@linkplain
51 * java.lang##wrapperClass wrapper class} for values of the primitive
52 * type {@code int}. An object of type {@code Integer} contains a
53 * single field whose type is {@code int}.
54 *
55 * <p>In addition, this class provides several methods for converting
56 * an {@code int} to a {@code String} and a {@code String} to an
57 * {@code int}, as well as other constants and methods useful when
58 * dealing with an {@code int}.
59 *
60 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
61 * class; programmers should treat instances that are {@linkplain #equals(Object) equal}
62 * as interchangeable and should not use instances for synchronization, mutexes, or
63 * with {@linkplain java.lang.ref.Reference object references}.
64 *
65 * <div class="preview-block">
66 * <div class="preview-comment">
67 * When preview features are enabled, {@code Integer} is a {@linkplain Class#isValue value class}.
68 * Use of value class instances for synchronization, mutexes, or with
69 * {@linkplain java.lang.ref.Reference object references} result in
70 * {@link IdentityException}.
71 * </div>
72 * </div>
73 *
74 * <p>Implementation note: The implementations of the "bit twiddling"
75 * methods (such as {@link #highestOneBit(int) highestOneBit} and
76 * {@link #numberOfTrailingZeros(int) 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 * @author Lee Boynton
82 * @author Arthur van Hoff
83 * @author Josh Bloch
84 * @author Joseph D. Darcy
85 * @since 1.0
86 */
87 @jdk.internal.MigratedValueClass
88 @jdk.internal.ValueBased
89 public final class Integer extends Number
90 implements Comparable<Integer>, Constable, ConstantDesc {
91 /**
92 * A constant holding the minimum value an {@code int} can
93 * have, -2<sup>31</sup>.
94 */
95 @Native public static final int MIN_VALUE = 0x80000000;
96
97 /**
98 * A constant holding the maximum value an {@code int} can
99 * have, 2<sup>31</sup>-1.
100 */
101 @Native public static final int MAX_VALUE = 0x7fffffff;
102
103 /**
104 * The {@code Class} instance representing the primitive type
105 * {@code int}.
106 *
107 * @since 1.1
108 */
109 public static final Class<Integer> TYPE = Class.getPrimitiveClass("int");
110
111 /**
112 * All possible chars for representing a number as a String
113 */
114 @Stable
115 static final byte[] digits = {
116 '0' , '1' , '2' , '3' , '4' , '5' ,
117 '6' , '7' , '8' , '9' , 'a' , 'b' ,
118 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
119 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
120 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
121 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
122 };
123
124 /**
125 * Returns a string representation of the first argument in the
126 * radix specified by the second argument.
127 *
128 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
129 * or larger than {@code Character.MAX_RADIX}, then the radix
130 * {@code 10} is used instead.
131 *
132 * <p>If the first argument is negative, the first element of the
133 * result is the ASCII minus character {@code '-'}
134 * ({@code '\u005Cu002D'}). If the first argument is not
135 * negative, no sign character appears in the result.
136 *
137 * <p>The remaining characters of the result represent the magnitude
138 * of the first argument. If the magnitude is zero, it is
139 * represented by a single zero character {@code '0'}
140 * ({@code '\u005Cu0030'}); otherwise, the first character of
141 * the representation of the magnitude will not be the zero
142 * character. The following ASCII characters are used as digits:
143 *
144 * <blockquote>
145 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
146 * </blockquote>
147 *
148 * These are {@code '\u005Cu0030'} through
149 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
150 * {@code '\u005Cu007A'}. If {@code radix} is
151 * <var>N</var>, then the first <var>N</var> of these characters
152 * are used as radix-<var>N</var> digits in the order shown. Thus,
153 * the digits for hexadecimal (radix 16) are
154 * {@code 0123456789abcdef}. If uppercase letters are
155 * desired, the {@link java.lang.String#toUpperCase()} method may
156 * be called on the result:
157 *
158 * <blockquote>
159 * {@code Integer.toString(n, 16).toUpperCase()}
160 * </blockquote>
161 *
162 * @param i an integer to be converted to a string.
163 * @param radix the radix to use in the string representation.
164 * @return a string representation of the argument in the specified radix.
165 * @see java.lang.Character#MAX_RADIX
166 * @see java.lang.Character#MIN_RADIX
167 */
168 public static String toString(int i, int radix) {
169 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
170 radix = 10;
171
172 /* Use the faster version */
173 if (radix == 10) {
174 return toString(i);
175 }
176
177 if (COMPACT_STRINGS) {
178 byte[] buf = new byte[33];
179 boolean negative = (i < 0);
180 int charPos = 32;
181
182 if (!negative) {
183 i = -i;
184 }
185
186 while (i <= -radix) {
187 buf[charPos--] = digits[-(i % radix)];
188 i = i / radix;
189 }
190 buf[charPos] = digits[-i];
191
192 if (negative) {
193 buf[--charPos] = '-';
194 }
195
196 return StringLatin1.newString(buf, charPos, (33 - charPos));
197 }
198 return toStringUTF16(i, radix);
199 }
200
201 private static String toStringUTF16(int i, int radix) {
202 byte[] buf = new byte[33 * 2];
203 boolean negative = (i < 0);
204 int charPos = 32;
205 if (!negative) {
206 i = -i;
207 }
208 while (i <= -radix) {
209 StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
210 i = i / radix;
211 }
212 StringUTF16.putChar(buf, charPos, digits[-i]);
213
214 if (negative) {
215 StringUTF16.putChar(buf, --charPos, '-');
216 }
217 return StringUTF16.newString(buf, charPos, (33 - charPos));
218 }
219
220 /**
221 * Returns a string representation of the first argument as an
222 * unsigned integer value in the radix specified by the second
223 * argument.
224 *
225 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
226 * or larger than {@code Character.MAX_RADIX}, then the radix
227 * {@code 10} is used instead.
228 *
229 * <p>Note that since the first argument is treated as an unsigned
230 * value, no leading sign character is printed.
231 *
232 * <p>If the magnitude is zero, it is represented by a single zero
233 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
234 * the first character of the representation of the magnitude will
235 * not be the zero character.
236 *
237 * <p>The behavior of radixes and the characters used as digits
238 * are the same as {@link #toString(int, int) toString}.
239 *
240 * @param i an integer to be converted to an unsigned string.
241 * @param radix the radix to use in the string representation.
242 * @return an unsigned string representation of the argument in the specified radix.
243 * @see #toString(int, int)
244 * @since 1.8
245 */
246 public static String toUnsignedString(int i, int radix) {
247 return Long.toUnsignedString(toUnsignedLong(i), radix);
248 }
249
250 /**
251 * Returns a string representation of the integer argument as an
252 * unsigned integer in base 16.
253 *
254 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
255 * if the argument is negative; otherwise, it is equal to the
256 * argument. This value is converted to a string of ASCII digits
257 * in hexadecimal (base 16) with no extra leading
258 * {@code 0}s.
259 *
260 * <p>The value of the argument can be recovered from the returned
261 * string {@code s} by calling {@link
262 * Integer#parseUnsignedInt(String, int)
263 * Integer.parseUnsignedInt(s, 16)}.
264 *
265 * <p>If the unsigned magnitude is zero, it is represented by a
266 * single zero character {@code '0'} ({@code '\u005Cu0030'});
267 * otherwise, the first character of the representation of the
268 * unsigned magnitude will not be the zero character. The
269 * following characters are used as hexadecimal digits:
270 *
271 * <blockquote>
272 * {@code 0123456789abcdef}
273 * </blockquote>
274 *
275 * These are the characters {@code '\u005Cu0030'} through
276 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
277 * {@code '\u005Cu0066'}. If uppercase letters are
278 * desired, the {@link java.lang.String#toUpperCase()} method may
279 * be called on the result:
280 *
281 * <blockquote>
282 * {@code Integer.toHexString(n).toUpperCase()}
283 * </blockquote>
284 *
285 * @apiNote
286 * The {@link java.util.HexFormat} class provides formatting and parsing
287 * of byte arrays and primitives to return a string or adding to an {@link Appendable}.
288 * {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
289 * with leading zeros and for byte arrays includes for each byte
290 * a delimiter, prefix, and suffix.
291 *
292 * @param i an integer to be converted to a string.
293 * @return the string representation of the unsigned integer value
294 * represented by the argument in hexadecimal (base 16).
295 * @see java.util.HexFormat
296 * @see #parseUnsignedInt(String, int)
297 * @see #toUnsignedString(int, int)
298 * @since 1.0.2
299 */
300 public static String toHexString(int i) {
301 return toUnsignedString0(i, 4);
302 }
303
304 /**
305 * Returns a string representation of the integer argument as an
306 * unsigned integer in base 8.
307 *
308 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
309 * if the argument is negative; otherwise, it is equal to the
310 * argument. This value is converted to a string of ASCII digits
311 * in octal (base 8) with no extra leading {@code 0}s.
312 *
313 * <p>The value of the argument can be recovered from the returned
314 * string {@code s} by calling {@link
315 * Integer#parseUnsignedInt(String, int)
316 * Integer.parseUnsignedInt(s, 8)}.
317 *
318 * <p>If the unsigned magnitude is zero, it is represented by a
319 * single zero character {@code '0'} ({@code '\u005Cu0030'});
320 * otherwise, the first character of the representation of the
321 * unsigned magnitude will not be the zero character. The
322 * following characters are used as octal digits:
323 *
324 * <blockquote>
325 * {@code 01234567}
326 * </blockquote>
327 *
328 * These are the characters {@code '\u005Cu0030'} through
329 * {@code '\u005Cu0037'}.
330 *
331 * @param i an integer to be converted to a string.
332 * @return the string representation of the unsigned integer value
333 * represented by the argument in octal (base 8).
334 * @see #parseUnsignedInt(String, int)
335 * @see #toUnsignedString(int, int)
336 * @since 1.0.2
337 */
338 public static String toOctalString(int i) {
339 return toUnsignedString0(i, 3);
340 }
341
342 /**
343 * Returns a string representation of the integer argument as an
344 * unsigned integer in base 2.
345 *
346 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
347 * if the argument is negative; otherwise it is equal to the
348 * argument. This value is converted to a string of ASCII digits
349 * in binary (base 2) with no extra leading {@code 0}s.
350 *
351 * <p>The value of the argument can be recovered from the returned
352 * string {@code s} by calling {@link
353 * Integer#parseUnsignedInt(String, int)
354 * Integer.parseUnsignedInt(s, 2)}.
355 *
356 * <p>If the unsigned magnitude is zero, it is represented by a
357 * single zero character {@code '0'} ({@code '\u005Cu0030'});
358 * otherwise, the first character of the representation of the
359 * unsigned magnitude will not be the zero character. The
360 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
361 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
362 *
363 * @param i an integer to be converted to a string.
364 * @return the string representation of the unsigned integer value
365 * represented by the argument in binary (base 2).
366 * @see #parseUnsignedInt(String, int)
367 * @see #toUnsignedString(int, int)
368 * @since 1.0.2
369 */
370 public static String toBinaryString(int i) {
371 return toUnsignedString0(i, 1);
372 }
373
374 /**
375 * Convert the integer to an unsigned number.
376 */
377 private static String toUnsignedString0(int val, int shift) {
378 // assert shift > 0 && shift <=5 : "Illegal shift value";
379 int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
380 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
381 if (COMPACT_STRINGS) {
382 byte[] buf = new byte[chars];
383 formatUnsignedInt(val, shift, buf, chars);
384 return new String(buf, LATIN1);
385 } else {
386 byte[] buf = new byte[chars * 2];
387 formatUnsignedIntUTF16(val, shift, buf, chars);
388 return new String(buf, UTF16);
389 }
390 }
391
392 /**
393 * Format an {@code int} (treated as unsigned) into a byte buffer (LATIN1 version). If
394 * {@code len} exceeds the formatted ASCII representation of {@code val},
395 * {@code buf} will be padded with leading zeroes.
396 *
397 * @param val the unsigned int to format
398 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
399 * @param buf the byte buffer to write to
400 * @param len the number of characters to write
401 */
402 private static void formatUnsignedInt(int val, int shift, byte[] buf, int len) {
403 int charPos = len;
404 int radix = 1 << shift;
405 int mask = radix - 1;
406 do {
407 buf[--charPos] = Integer.digits[val & mask];
408 val >>>= shift;
409 } while (charPos > 0);
410 }
411
412 /**
413 * Format an {@code int} (treated as unsigned) into a byte buffer (UTF16 version). If
414 * {@code len} exceeds the formatted ASCII representation of {@code val},
415 * {@code buf} will be padded with leading zeroes.
416 *
417 * @param val the unsigned int to format
418 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
419 * @param buf the byte buffer to write to
420 * @param len the number of characters to write
421 */
422 private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int len) {
423 int charPos = len;
424 int radix = 1 << shift;
425 int mask = radix - 1;
426 do {
427 StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
428 val >>>= shift;
429 } while (charPos > 0);
430 }
431
432 /**
433 * Returns a {@code String} object representing the
434 * specified integer. The argument is converted to signed decimal
435 * representation and returned as a string, exactly as if the
436 * argument and radix 10 were given as arguments to the {@link
437 * #toString(int, int)} method.
438 *
439 * @param i an integer to be converted.
440 * @return a string representation of the argument in base 10.
441 */
442 @IntrinsicCandidate
443 public static String toString(int i) {
444 int size = DecimalDigits.stringSize(i);
445 if (COMPACT_STRINGS) {
446 byte[] buf = new byte[size];
447 DecimalDigits.uncheckedGetCharsLatin1(i, size, buf);
448 return new String(buf, LATIN1);
449 } else {
450 byte[] buf = new byte[size * 2];
451 DecimalDigits.uncheckedGetCharsUTF16(i, size, buf);
452 return new String(buf, UTF16);
453 }
454 }
455
456 /**
457 * Returns a string representation of the argument as an unsigned
458 * decimal value.
459 *
460 * The argument is converted to unsigned decimal representation
461 * and returned as a string exactly as if the argument and radix
462 * 10 were given as arguments to the {@link #toUnsignedString(int,
463 * int)} method.
464 *
465 * @param i an integer to be converted to an unsigned string.
466 * @return an unsigned string representation of the argument.
467 * @see #toUnsignedString(int, int)
468 * @since 1.8
469 */
470 public static String toUnsignedString(int i) {
471 return Long.toString(toUnsignedLong(i));
472 }
473
474 /**
475 * Parses the string argument as a signed integer in the radix
476 * specified by the second argument. The characters in the string
477 * must all be digits of the specified radix (as determined by
478 * whether {@link java.lang.Character#digit(char, int)} returns a
479 * nonnegative value), except that the first character may be an
480 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
481 * indicate a negative value or an ASCII plus sign {@code '+'}
482 * ({@code '\u005Cu002B'}) to indicate a positive value. The
483 * resulting integer value is returned.
484 *
485 * <p>An exception of type {@code NumberFormatException} is
486 * thrown if any of the following situations occurs:
487 * <ul>
488 * <li>The first argument is {@code null} or is a string of
489 * length zero.
490 *
491 * <li>The radix is either smaller than
492 * {@link java.lang.Character#MIN_RADIX} or
493 * larger than {@link java.lang.Character#MAX_RADIX}.
494 *
495 * <li>Any character of the string is not a digit of the specified
496 * radix, except that the first character may be a minus sign
497 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign
498 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
499 * string is longer than length 1.
500 *
501 * <li>The value represented by the string is not a value of type
502 * {@code int}.
503 * </ul>
504 *
505 * <p>Examples:
506 * <blockquote><pre>
507 * parseInt("0", 10) returns 0
508 * parseInt("473", 10) returns 473
509 * parseInt("+42", 10) returns 42
510 * parseInt("-0", 10) returns 0
511 * parseInt("-FF", 16) returns -255
512 * parseInt("1100110", 2) returns 102
513 * parseInt("2147483647", 10) returns 2147483647
514 * parseInt("-2147483648", 10) returns -2147483648
515 * parseInt("2147483648", 10) throws a NumberFormatException
516 * parseInt("99", 8) throws a NumberFormatException
517 * parseInt("Kona", 10) throws a NumberFormatException
518 * parseInt("Kona", 27) returns 411787
519 * </pre></blockquote>
520 *
521 * @param s the {@code String} containing the integer
522 * representation to be parsed
523 * @param radix the radix to be used while parsing {@code s}.
524 * @return the integer represented by the string argument in the
525 * specified radix.
526 * @throws NumberFormatException if the {@code String}
527 * does not contain a parsable {@code int}.
528 */
529 public static int parseInt(String s, int radix)
530 throws NumberFormatException {
531 /*
532 * WARNING: This method may be invoked early during VM initialization
533 * before IntegerCache is initialized. Care must be taken to not use
534 * the valueOf method.
535 */
536
537 if (s == null) {
538 throw new NumberFormatException("Cannot parse null string");
539 }
540
541 if (radix < Character.MIN_RADIX) {
542 throw new NumberFormatException(String.format(
543 "radix %s less than Character.MIN_RADIX", radix));
544 }
545
546 if (radix > Character.MAX_RADIX) {
547 throw new NumberFormatException(String.format(
548 "radix %s greater than Character.MAX_RADIX", radix));
549 }
550
551 int len = s.length();
552 if (len == 0) {
553 throw NumberFormatException.forInputString("", radix);
554 }
555 int digit = ~0xFF;
556 int i = 0;
557 char firstChar = s.charAt(i++);
558 if (firstChar != '-' && firstChar != '+') {
559 digit = digit(firstChar, radix);
560 }
561 if (digit >= 0 || digit == ~0xFF && len > 1) {
562 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
563 int multmin = limit / radix;
564 int result = -(digit & 0xFF);
565 boolean inRange = true;
566 /* Accumulating negatively avoids surprises near MAX_VALUE */
567 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
568 && (inRange = result > multmin
569 || result == multmin && digit <= radix * multmin - limit)) {
570 result = radix * result - digit;
571 }
572 if (inRange && i == len && digit >= 0) {
573 return firstChar != '-' ? -result : result;
574 }
575 }
576 throw NumberFormatException.forInputString(s, radix);
577 }
578
579 /**
580 * Parses the {@link CharSequence} argument as a signed {@code int} in the
581 * specified {@code radix}, beginning at the specified {@code beginIndex}
582 * and extending to {@code endIndex - 1}.
583 *
584 * <p>The method does not take steps to guard against the
585 * {@code CharSequence} being mutated while parsing.
586 *
587 * @param s the {@code CharSequence} containing the {@code int}
588 * representation to be parsed
589 * @param beginIndex the beginning index, inclusive.
590 * @param endIndex the ending index, exclusive.
591 * @param radix the radix to be used while parsing {@code s}.
592 * @return the signed {@code int} represented by the subsequence in
593 * the specified radix.
594 * @throws NullPointerException if {@code s} is null.
595 * @throws IndexOutOfBoundsException if {@code beginIndex} is
596 * negative, or if {@code beginIndex} is greater than
597 * {@code endIndex} or if {@code endIndex} is greater than
598 * {@code s.length()}.
599 * @throws NumberFormatException if the {@code CharSequence} does not
600 * contain a parsable {@code int} in the specified
601 * {@code radix}, or if {@code radix} is either smaller than
602 * {@link java.lang.Character#MIN_RADIX} or larger than
603 * {@link java.lang.Character#MAX_RADIX}.
604 * @since 9
605 */
606 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
607 throws NumberFormatException {
608 Objects.requireNonNull(s);
609 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
610
611 if (radix < Character.MIN_RADIX) {
612 throw new NumberFormatException(String.format(
613 "radix %s less than Character.MIN_RADIX", radix));
614 }
615
616 if (radix > Character.MAX_RADIX) {
617 throw new NumberFormatException(String.format(
618 "radix %s greater than Character.MAX_RADIX", radix));
619 }
620
621 /*
622 * While s can be concurrently modified, it is ensured that each
623 * of its characters is read at most once, from lower to higher indices.
624 * This is obtained by reading them using the pattern s.charAt(i++),
625 * and by not updating i anywhere else.
626 */
627 if (beginIndex == endIndex) {
628 throw NumberFormatException.forInputString("", radix);
629 }
630 int digit = ~0xFF;
631 int i = beginIndex;
632 char firstChar = s.charAt(i++);
633 if (firstChar != '-' && firstChar != '+') {
634 digit = digit(firstChar, radix);
635 }
636 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
637 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
638 int multmin = limit / radix;
639 int result = -(digit & 0xFF);
640 boolean inRange = true;
641 /* Accumulating negatively avoids surprises near MAX_VALUE */
642 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
643 && (inRange = result > multmin
644 || result == multmin && digit <= radix * multmin - limit)) {
645 result = radix * result - digit;
646 }
647 if (inRange && i == endIndex && digit >= 0) {
648 return firstChar != '-' ? -result : result;
649 }
650 }
651 throw NumberFormatException.forCharSequence(s, beginIndex,
652 endIndex, i - (digit < -1 ? 0 : 1));
653 }
654
655 /**
656 * Parses the string argument as a signed decimal integer. The
657 * characters in the string must all be decimal digits, except
658 * that the first character may be an ASCII minus sign {@code '-'}
659 * ({@code '\u005Cu002D'}) to indicate a negative value or an
660 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
661 * indicate a positive value. The resulting integer value is
662 * returned, exactly as if the argument and the radix 10 were
663 * given as arguments to the {@link #parseInt(java.lang.String,
664 * int)} method.
665 *
666 * @param s a {@code String} containing the {@code int}
667 * representation to be parsed
668 * @return the integer value represented by the argument in decimal.
669 * @throws NumberFormatException if the string does not contain a
670 * parsable integer.
671 */
672 public static int parseInt(String s) throws NumberFormatException {
673 return parseInt(s, 10);
674 }
675
676 /**
677 * Parses the string argument as an unsigned integer in the radix
678 * specified by the second argument. An unsigned integer maps the
679 * values usually associated with negative numbers to positive
680 * numbers larger than {@code MAX_VALUE}.
681 *
682 * The characters in the string must all be digits of the
683 * specified radix (as determined by whether {@link
684 * java.lang.Character#digit(char, int)} returns a nonnegative
685 * value), except that the first character may be an ASCII plus
686 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
687 * integer value is returned.
688 *
689 * <p>An exception of type {@code NumberFormatException} is
690 * thrown if any of the following situations occurs:
691 * <ul>
692 * <li>The first argument is {@code null} or is a string of
693 * length zero.
694 *
695 * <li>The radix is either smaller than
696 * {@link java.lang.Character#MIN_RADIX} or
697 * larger than {@link java.lang.Character#MAX_RADIX}.
698 *
699 * <li>Any character of the string is not a digit of the specified
700 * radix, except that the first character may be a plus sign
701 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
702 * string is longer than length 1.
703 *
704 * <li>The value represented by the string is larger than the
705 * largest unsigned {@code int}, 2<sup>32</sup>-1.
706 *
707 * </ul>
708 *
709 *
710 * @param s the {@code String} containing the unsigned integer
711 * representation to be parsed
712 * @param radix the radix to be used while parsing {@code s}.
713 * @return the integer represented by the string argument in the
714 * specified radix.
715 * @throws NumberFormatException if the {@code String}
716 * does not contain a parsable {@code int}.
717 * @since 1.8
718 */
719 public static int parseUnsignedInt(String s, int radix)
720 throws NumberFormatException {
721 if (s == null) {
722 throw new NumberFormatException("Cannot parse null string");
723 }
724
725 if (radix < Character.MIN_RADIX) {
726 throw new NumberFormatException(String.format(
727 "radix %s less than Character.MIN_RADIX", radix));
728 }
729
730 if (radix > Character.MAX_RADIX) {
731 throw new NumberFormatException(String.format(
732 "radix %s greater than Character.MAX_RADIX", radix));
733 }
734
735 int len = s.length();
736 if (len == 0) {
737 throw NumberFormatException.forInputString(s, radix);
738 }
739 int i = 0;
740 char firstChar = s.charAt(i++);
741 if (firstChar == '-') {
742 throw new NumberFormatException(String.format(
743 "Illegal leading minus sign on unsigned string %s.", s));
744 }
745 int digit = ~0xFF;
746 if (firstChar != '+') {
747 digit = digit(firstChar, radix);
748 }
749 if (digit >= 0 || digit == ~0xFF && len > 1) {
750 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
751 int result = digit & 0xFF;
752 boolean inRange = true;
753 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
754 && (inRange = compareUnsigned(result, multmax) < 0
755 || result == multmax && digit < -radix * multmax)) {
756 result = radix * result + digit;
757 }
758 if (inRange && i == len && digit >= 0) {
759 return result;
760 }
761 }
762 if (digit < 0) {
763 throw NumberFormatException.forInputString(s, radix);
764 }
765 throw new NumberFormatException(String.format(
766 "String value %s exceeds range of unsigned int.", s));
767 }
768
769 /**
770 * Parses the {@link CharSequence} argument as an unsigned {@code int} in
771 * the specified {@code radix}, beginning at the specified
772 * {@code beginIndex} and extending to {@code endIndex - 1}.
773 *
774 * <p>The method does not take steps to guard against the
775 * {@code CharSequence} being mutated while parsing.
776 *
777 * @param s the {@code CharSequence} containing the unsigned
778 * {@code int} representation to be parsed
779 * @param beginIndex the beginning index, inclusive.
780 * @param endIndex the ending index, exclusive.
781 * @param radix the radix to be used while parsing {@code s}.
782 * @return the unsigned {@code int} represented by the subsequence in
783 * the specified radix.
784 * @throws NullPointerException if {@code s} is null.
785 * @throws IndexOutOfBoundsException if {@code beginIndex} is
786 * negative, or if {@code beginIndex} is greater than
787 * {@code endIndex} or if {@code endIndex} is greater than
788 * {@code s.length()}.
789 * @throws NumberFormatException if the {@code CharSequence} does not
790 * contain a parsable unsigned {@code int} in the specified
791 * {@code radix}, or if {@code radix} is either smaller than
792 * {@link java.lang.Character#MIN_RADIX} or larger than
793 * {@link java.lang.Character#MAX_RADIX}.
794 * @since 9
795 */
796 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
797 throws NumberFormatException {
798 Objects.requireNonNull(s);
799 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
800
801 if (radix < Character.MIN_RADIX) {
802 throw new NumberFormatException(String.format(
803 "radix %s less than Character.MIN_RADIX", radix));
804 }
805
806 if (radix > Character.MAX_RADIX) {
807 throw new NumberFormatException(String.format(
808 "radix %s greater than Character.MAX_RADIX", radix));
809 }
810
811 /*
812 * While s can be concurrently modified, it is ensured that each
813 * of its characters is read at most once, from lower to higher indices.
814 * This is obtained by reading them using the pattern s.charAt(i++),
815 * and by not updating i anywhere else.
816 */
817 if (beginIndex == endIndex) {
818 throw NumberFormatException.forInputString("", radix);
819 }
820 int i = beginIndex;
821 char firstChar = s.charAt(i++);
822 if (firstChar == '-') {
823 throw new NumberFormatException(
824 "Illegal leading minus sign on unsigned string " + s + ".");
825 }
826 int digit = ~0xFF;
827 if (firstChar != '+') {
828 digit = digit(firstChar, radix);
829 }
830 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
831 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
832 int result = digit & 0xFF;
833 boolean inRange = true;
834 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
835 && (inRange = compareUnsigned(result, multmax) < 0
836 || result == multmax && digit < -radix * multmax)) {
837 result = radix * result + digit;
838 }
839 if (inRange && i == endIndex && digit >= 0) {
840 return result;
841 }
842 }
843 if (digit < 0) {
844 throw NumberFormatException.forCharSequence(s, beginIndex,
845 endIndex, i - (digit < -1 ? 0 : 1));
846 }
847 throw new NumberFormatException(String.format(
848 "String value %s exceeds range of unsigned int.", s));
849 }
850
851 /**
852 * Parses the string argument as an unsigned decimal integer. The
853 * characters in the string must all be decimal digits, except
854 * that the first character may be an ASCII plus sign {@code
855 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
856 * is returned, exactly as if the argument and the radix 10 were
857 * given as arguments to the {@link
858 * #parseUnsignedInt(java.lang.String, int)} method.
859 *
860 * @param s a {@code String} containing the unsigned {@code int}
861 * representation to be parsed
862 * @return the unsigned integer value represented by the argument in decimal.
863 * @throws NumberFormatException if the string does not contain a
864 * parsable unsigned integer.
865 * @since 1.8
866 */
867 public static int parseUnsignedInt(String s) throws NumberFormatException {
868 return parseUnsignedInt(s, 10);
869 }
870
871 /**
872 * Returns an {@code Integer} object holding the value
873 * extracted from the specified {@code String} when parsed
874 * with the radix given by the second argument. The first argument
875 * is interpreted as representing a signed integer in the radix
876 * specified by the second argument, exactly as if the arguments
877 * were given to the {@link #parseInt(java.lang.String, int)}
878 * method. The result is an {@code Integer} object that
879 * represents the integer value specified by the string.
880 *
881 * <p>In other words, this method returns an {@code Integer}
882 * object equal to the value of:
883 *
884 * <blockquote>
885 * {@code Integer.valueOf(Integer.parseInt(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 an {@code Integer} object holding the value
891 * represented by the string argument in the specified
892 * radix.
893 * @throws NumberFormatException if the {@code String}
894 * does not contain a parsable {@code int}.
895 */
896 public static Integer valueOf(String s, int radix) throws NumberFormatException {
897 return Integer.valueOf(parseInt(s,radix));
898 }
899
900 /**
901 * Returns an {@code Integer} object holding the
902 * value of the specified {@code String}. The argument is
903 * interpreted as representing a signed decimal integer, exactly
904 * as if the argument were given to the {@link
905 * #parseInt(java.lang.String)} method. The result is an
906 * {@code Integer} object that represents the integer value
907 * specified by the string.
908 *
909 * <p>In other words, this method returns an {@code Integer}
910 * object equal to the value of:
911 *
912 * <blockquote>
913 * {@code Integer.valueOf(Integer.parseInt(s))}
914 * </blockquote>
915 *
916 * @param s the string to be parsed.
917 * @return an {@code Integer} object holding the value
918 * represented by the string argument.
919 * @throws NumberFormatException if the string cannot be parsed
920 * as an integer.
921 */
922 public static Integer valueOf(String s) throws NumberFormatException {
923 return Integer.valueOf(parseInt(s, 10));
924 }
925
926 /**
927 * Cache to support the object identity semantics of autoboxing for values between
928 * -128 and 127 (inclusive) as required by JLS.
929 *
930 * The cache is initialized on first usage. The size of the cache
931 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
932 * During VM initialization, java.lang.Integer.IntegerCache.high property
933 * may be set and saved in the private system properties in the
934 * jdk.internal.misc.VM class.
935 *
936 * WARNING: The cache is archived with CDS and reloaded from the shared
937 * archive at runtime. The archived cache (Integer[]) and Integer objects
938 * reside in the closed archive heap regions. Care should be taken when
939 * changing the implementation and the cache array should not be assigned
940 * with new Integer object(s) after initialization.
941 */
942
943 private static final class IntegerCache {
944 static final int low = -128;
945 static final int high;
946
947 @Stable
948 static final Integer[] cache;
949 static Integer[] archivedCache;
950
951 static {
952 // high value may be configured by property
953 int h = 127;
954 String integerCacheHighPropValue =
955 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
956 if (integerCacheHighPropValue != null) {
957 try {
958 h = Math.max(parseInt(integerCacheHighPropValue), 127);
959 // Maximum array size is Integer.MAX_VALUE
960 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
961 } catch( NumberFormatException nfe) {
962 // If the property cannot be parsed into an int, ignore it.
963 }
964 }
965 high = h;
966
967 // Load IntegerCache.archivedCache from archive, if possible
968 CDS.initializeFromArchive(IntegerCache.class);
969 int size = (high - low) + 1;
970
971 // Use the archived cache if it exists and is large enough
972 if (archivedCache == null || size > archivedCache.length) {
973 Integer[] c = new Integer[size];
974 int j = low;
975 // If archive has Integer cache, we must use all instances from it.
976 // Otherwise, the identity checks between archived Integers and
977 // runtime-cached Integers would fail.
978 int archivedSize = (archivedCache == null) ? 0 : archivedCache.length;
979 for (int i = 0; i < archivedSize; i++) {
980 c[i] = archivedCache[i];
981 assert j == archivedCache[i];
982 j++;
983 }
984 // Fill the rest of the cache.
985 for (int i = archivedSize; i < size; i++) {
986 c[i] = new Integer(j++);
987 }
988 archivedCache = c;
989 }
990 cache = archivedCache;
991 // range [-128, 127] must be interned (JLS7 5.1.7)
992 assert IntegerCache.high >= 127;
993 }
994
995 private IntegerCache() {}
996 }
997
998 /**
999 * Returns an {@code Integer} instance representing the specified
1000 * {@code int} value.
1001 * <div class="preview-block">
1002 * <div class="preview-comment">
1003 * <p>
1004 * - When preview features are NOT enabled, {@code Integer} is an identity class.
1005 * If a new {@code Integer} instance is not
1006 * required, this method should generally be used in preference to
1007 * the constructor {@link #Integer(int)}, as this method is likely
1008 * to yield significantly better space and time performance by
1009 * caching frequently requested values.
1010 * This method will always cache values in the range -128 to 127,
1011 * inclusive, and may cache other values outside of this range.
1012 * </p>
1013 * <p>
1014 * - When preview features are enabled, {@code Integer} is a {@linkplain Class#isValue value class}.
1015 * The {@code valueOf} behavior is the same as invoking the constructor,
1016 * whether cached or not.
1017 * </p>
1018 * </div>
1019 * </div>
1020 *
1021 * @param i an {@code int} value.
1022 * @return an {@code Integer} instance representing {@code i}.
1023 * @since 1.5
1024 */
1025 @IntrinsicCandidate
1026 @DeserializeConstructor
1027 public static Integer valueOf(int i) {
1028 if (!PreviewFeatures.isEnabled()) {
1029 if (i >= IntegerCache.low && i <= IntegerCache.high)
1030 return IntegerCache.cache[i + (-IntegerCache.low)];
1031 }
1032 return new Integer(i);
1033 }
1034
1035 /**
1036 * The value of the {@code Integer}.
1037 *
1038 * @serial
1039 */
1040 private final int value;
1041
1042 /**
1043 * Constructs a newly allocated {@code Integer} object that
1044 * represents the specified {@code int} value.
1045 *
1046 * @param value the value to be represented by the
1047 * {@code Integer} object.
1048 *
1049 * @deprecated
1050 * It is rarely appropriate to use this constructor. The static factory
1051 * {@link #valueOf(int)} is generally a better choice, as it is
1052 * likely to yield significantly better space and time performance.
1053 */
1054 @Deprecated(since="9")
1055 public Integer(int value) {
1056 this.value = value;
1057 }
1058
1059 /**
1060 * Constructs a newly allocated {@code Integer} object that
1061 * represents the {@code int} value indicated by the
1062 * {@code String} parameter. The string is converted to an
1063 * {@code int} value in exactly the manner used by the
1064 * {@code parseInt} method for radix 10.
1065 *
1066 * @param s the {@code String} to be converted to an {@code Integer}.
1067 * @throws NumberFormatException if the {@code String} does not
1068 * contain a parsable integer.
1069 *
1070 * @deprecated
1071 * It is rarely appropriate to use this constructor.
1072 * Use {@link #parseInt(String)} to convert a string to a
1073 * {@code int} primitive, or use {@link #valueOf(String)}
1074 * to convert a string to an {@code Integer} object.
1075 */
1076 @Deprecated(since="9")
1077 public Integer(String s) throws NumberFormatException {
1078 this.value = parseInt(s, 10);
1079 }
1080
1081 /**
1082 * Returns the value of this {@code Integer} as a {@code byte}
1083 * after a narrowing primitive conversion.
1084 * @jls 5.1.3 Narrowing Primitive Conversion
1085 */
1086 public byte byteValue() {
1087 return (byte)value;
1088 }
1089
1090 /**
1091 * Returns the value of this {@code Integer} as a {@code short}
1092 * after a narrowing primitive conversion.
1093 * @jls 5.1.3 Narrowing Primitive Conversion
1094 */
1095 public short shortValue() {
1096 return (short)value;
1097 }
1098
1099 /**
1100 * Returns the value of this {@code Integer} as an
1101 * {@code int}.
1102 */
1103 @IntrinsicCandidate
1104 public int intValue() {
1105 return value;
1106 }
1107
1108 /**
1109 * Returns the value of this {@code Integer} as a {@code long}
1110 * after a widening primitive conversion.
1111 * @jls 5.1.2 Widening Primitive Conversion
1112 * @see Integer#toUnsignedLong(int)
1113 */
1114 public long longValue() {
1115 return (long)value;
1116 }
1117
1118 /**
1119 * Returns the value of this {@code Integer} as a {@code float}
1120 * after a widening primitive conversion.
1121 * @jls 5.1.2 Widening Primitive Conversion
1122 */
1123 public float floatValue() {
1124 return (float)value;
1125 }
1126
1127 /**
1128 * Returns the value of this {@code Integer} as a {@code double}
1129 * after a widening primitive conversion.
1130 * @jls 5.1.2 Widening Primitive Conversion
1131 */
1132 public double doubleValue() {
1133 return (double)value;
1134 }
1135
1136 /**
1137 * Returns a {@code String} object representing this
1138 * {@code Integer}'s value. The value is converted to signed
1139 * decimal representation and returned as a string, exactly as if
1140 * the integer value were given as an argument to the {@link
1141 * java.lang.Integer#toString(int)} method.
1142 *
1143 * @return a string representation of the value of this object in
1144 * base 10.
1145 */
1146 public String toString() {
1147 return toString(value);
1148 }
1149
1150 /**
1151 * Returns a hash code for this {@code Integer}.
1152 *
1153 * @return a hash code value for this object, equal to the
1154 * primitive {@code int} value represented by this
1155 * {@code Integer} object.
1156 */
1157 @Override
1158 public int hashCode() {
1159 return Integer.hashCode(value);
1160 }
1161
1162 /**
1163 * Returns a hash code for an {@code int} value; compatible with
1164 * {@code Integer.hashCode()}.
1165 *
1166 * @param value the value to hash
1167 * @since 1.8
1168 *
1169 * @return a hash code value for an {@code int} value.
1170 */
1171 public static int hashCode(int value) {
1172 return value;
1173 }
1174
1175 /**
1176 * Compares this object to the specified object. The result is
1177 * {@code true} if and only if the argument is not
1178 * {@code null} and is an {@code Integer} object that
1179 * contains the same {@code int} value as this object.
1180 *
1181 * @param obj the object to compare with.
1182 * @return {@code true} if the objects are the same;
1183 * {@code false} otherwise.
1184 */
1185 public boolean equals(Object obj) {
1186 if (obj instanceof Integer i) {
1187 return value == i.intValue();
1188 }
1189 return false;
1190 }
1191
1192 /**
1193 * Determines the integer value of the system property with the
1194 * specified name.
1195 *
1196 * <p>The first argument is treated as the name of a system
1197 * property. System properties are accessible through the {@link
1198 * java.lang.System#getProperty(java.lang.String)} method. The
1199 * string value of this property is then interpreted as an integer
1200 * value using the grammar supported by {@link Integer#decode decode} and
1201 * an {@code Integer} object representing this value is returned.
1202 *
1203 * <p>If there is no property with the specified name, if the
1204 * specified name is empty or {@code null}, or if the property
1205 * does not have the correct numeric format, then {@code null} is
1206 * returned.
1207 *
1208 * <p>In other words, this method returns an {@code Integer}
1209 * object equal to the value of:
1210 *
1211 * <blockquote>
1212 * {@code getInteger(nm, null)}
1213 * </blockquote>
1214 *
1215 * @param nm property name.
1216 * @return the {@code Integer} value of the property.
1217 * @see java.lang.System#getProperty(java.lang.String)
1218 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1219 */
1220 public static Integer getInteger(String nm) {
1221 return getInteger(nm, null);
1222 }
1223
1224 /**
1225 * Determines the integer value of the system property with the
1226 * specified name.
1227 *
1228 * <p>The first argument is treated as the name of a system
1229 * property. System properties are accessible through the {@link
1230 * java.lang.System#getProperty(java.lang.String)} method. The
1231 * string value of this property is then interpreted as an integer
1232 * value using the grammar supported by {@link Integer#decode decode} and
1233 * an {@code Integer} object representing this value is returned.
1234 *
1235 * <p>The second argument is the default value. An {@code Integer} object
1236 * that represents the value of the second argument is returned if there
1237 * is no property of the specified name, if the property does not have
1238 * the correct numeric format, or if the specified name is empty or
1239 * {@code null}.
1240 *
1241 * <p>In other words, this method returns an {@code Integer} object
1242 * equal to the value of:
1243 *
1244 * <blockquote>
1245 * {@code getInteger(nm, Integer.valueOf(val))}
1246 * </blockquote>
1247 *
1248 * but in practice it may be implemented in a manner such as:
1249 *
1250 * <blockquote><pre>
1251 * Integer result = getInteger(nm, null);
1252 * return (result == null) ? Integer.valueOf(val) : result;
1253 * </pre></blockquote>
1254 *
1255 * to avoid the unnecessary allocation of an {@code Integer}
1256 * object when the default value is not needed.
1257 *
1258 * @param nm property name.
1259 * @param val default value.
1260 * @return the {@code Integer} value of the property.
1261 * @see java.lang.System#getProperty(java.lang.String)
1262 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1263 */
1264 public static Integer getInteger(String nm, int val) {
1265 Integer result = getInteger(nm, null);
1266 return (result == null) ? Integer.valueOf(val) : result;
1267 }
1268
1269 /**
1270 * Returns the integer value of the system property with the
1271 * specified name. The first argument is treated as the name of a
1272 * system property. System properties are accessible through the
1273 * {@link java.lang.System#getProperty(java.lang.String)} method.
1274 * The string value of this property is then interpreted as an
1275 * integer value, as per the {@link Integer#decode decode} method,
1276 * and an {@code Integer} object representing this value is
1277 * returned; in summary:
1278 *
1279 * <ul><li>If the property value begins with the two ASCII characters
1280 * {@code 0x} or the ASCII character {@code #}, not
1281 * followed by a minus sign, then the rest of it is parsed as a
1282 * hexadecimal integer exactly as by the method
1283 * {@link #valueOf(java.lang.String, int)} with radix 16.
1284 * <li>If the property value begins with the ASCII character
1285 * {@code 0} followed by another character, it is parsed as an
1286 * octal integer exactly as by the method
1287 * {@link #valueOf(java.lang.String, int)} with radix 8.
1288 * <li>Otherwise, the property value is parsed as a decimal integer
1289 * exactly as by the method {@link #valueOf(java.lang.String, int)}
1290 * with radix 10.
1291 * </ul>
1292 *
1293 * <p>The second argument is the default value. The default value is
1294 * returned if there is no property of the specified name, if the
1295 * property does not have the correct numeric format, or if the
1296 * specified name is empty or {@code null}.
1297 *
1298 * @param nm property name.
1299 * @param val default value.
1300 * @return the {@code Integer} value of the property.
1301 * @see System#getProperty(java.lang.String)
1302 * @see System#getProperty(java.lang.String, java.lang.String)
1303 */
1304 public static Integer getInteger(String nm, Integer val) {
1305 String v = nm != null && !nm.isEmpty() ? System.getProperty(nm) : null;
1306 if (v != null) {
1307 try {
1308 return Integer.decode(v);
1309 } catch (NumberFormatException e) {
1310 }
1311 }
1312 return val;
1313 }
1314
1315 /**
1316 * Decodes a {@code String} into an {@code Integer}.
1317 * Accepts decimal, hexadecimal, and octal numbers given
1318 * by the following grammar:
1319 *
1320 * <blockquote>
1321 * <dl>
1322 * <dt><i>DecodableString:</i>
1323 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1324 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1325 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1326 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1327 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1328 *
1329 * <dt><i>Sign:</i>
1330 * <dd>{@code -}
1331 * <dd>{@code +}
1332 * </dl>
1333 * </blockquote>
1334 *
1335 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1336 * are as defined in section {@jls 3.10.1} of
1337 * <cite>The Java Language Specification</cite>,
1338 * except that underscores are not accepted between digits.
1339 *
1340 * <p>The sequence of characters following an optional
1341 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1342 * "{@code #}", or leading zero) is parsed as by the {@code
1343 * Integer.parseInt} method with the indicated radix (10, 16, or
1344 * 8). This sequence of characters must represent a positive
1345 * value or a {@link NumberFormatException} will be thrown. The
1346 * result is negated if first character of the specified {@code
1347 * String} is the minus sign. No whitespace characters are
1348 * permitted in the {@code String}.
1349 *
1350 * @param nm the {@code String} to decode.
1351 * @return an {@code Integer} object holding the {@code int}
1352 * value represented by {@code nm}
1353 * @throws NumberFormatException if the {@code String} does not
1354 * contain a parsable integer.
1355 * @see java.lang.Integer#parseInt(java.lang.String, int)
1356 */
1357 public static Integer decode(String nm) throws NumberFormatException {
1358 int radix = 10;
1359 int index = 0;
1360 boolean negative = false;
1361 int result;
1362
1363 if (nm.isEmpty())
1364 throw new NumberFormatException("Zero length string");
1365 char firstChar = nm.charAt(0);
1366 // Handle sign, if present
1367 if (firstChar == '-') {
1368 negative = true;
1369 index++;
1370 } else if (firstChar == '+')
1371 index++;
1372
1373 // Handle radix specifier, if present
1374 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1375 index += 2;
1376 radix = 16;
1377 }
1378 else if (nm.startsWith("#", index)) {
1379 index ++;
1380 radix = 16;
1381 }
1382 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1383 index ++;
1384 radix = 8;
1385 }
1386
1387 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1388 throw new NumberFormatException("Sign character in wrong position");
1389
1390 try {
1391 result = parseInt(nm, index, nm.length(), radix);
1392 result = negative ? -result : result;
1393 } catch (NumberFormatException e) {
1394 // If number is Integer.MIN_VALUE, we'll end up here. The next line
1395 // handles this case, and causes any genuine format error to be
1396 // rethrown.
1397 String constant = negative ? ("-" + nm.substring(index))
1398 : nm.substring(index);
1399 result = parseInt(constant, radix);
1400 }
1401 return result;
1402 }
1403
1404 /**
1405 * Compares two {@code Integer} objects numerically.
1406 *
1407 * @param anotherInteger the {@code Integer} to be compared.
1408 * @return the value {@code 0} if this {@code Integer} is
1409 * equal to the argument {@code Integer}; a value less than
1410 * {@code 0} if this {@code Integer} is numerically less
1411 * than the argument {@code Integer}; and a value greater
1412 * than {@code 0} if this {@code Integer} is numerically
1413 * greater than the argument {@code Integer} (signed
1414 * comparison).
1415 * @since 1.2
1416 */
1417 public int compareTo(Integer anotherInteger) {
1418 return compare(this.value, anotherInteger.value);
1419 }
1420
1421 /**
1422 * Compares two {@code int} values numerically.
1423 * The value returned is identical to what would be returned by:
1424 * <pre>
1425 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1426 * </pre>
1427 *
1428 * @param x the first {@code int} to compare
1429 * @param y the second {@code int} to compare
1430 * @return the value {@code 0} if {@code x == y};
1431 * a value less than {@code 0} if {@code x < y}; and
1432 * a value greater than {@code 0} if {@code x > y}
1433 * @since 1.7
1434 */
1435 public static int compare(int x, int y) {
1436 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1437 }
1438
1439 /**
1440 * Compares two {@code int} values numerically treating the values
1441 * as unsigned.
1442 *
1443 * @param x the first {@code int} to compare
1444 * @param y the second {@code int} to compare
1445 * @return the value {@code 0} if {@code x == y}; a value less
1446 * than {@code 0} if {@code x < y} as unsigned values; and
1447 * a value greater than {@code 0} if {@code x > y} as
1448 * unsigned values
1449 * @since 1.8
1450 */
1451 @IntrinsicCandidate
1452 public static int compareUnsigned(int x, int y) {
1453 return compare(x + MIN_VALUE, y + MIN_VALUE);
1454 }
1455
1456 /**
1457 * Converts the argument to a {@code long} by an unsigned
1458 * conversion. In an unsigned conversion to a {@code long}, the
1459 * high-order 32 bits of the {@code long} are zero and the
1460 * low-order 32 bits are equal to the bits of the integer
1461 * argument.
1462 *
1463 * Consequently, zero and positive {@code int} values are mapped
1464 * to a numerically equal {@code long} value and negative {@code
1465 * int} values are mapped to a {@code long} value equal to the
1466 * input plus 2<sup>32</sup>.
1467 *
1468 * @param x the value to convert to an unsigned {@code long}
1469 * @return the argument converted to {@code long} by an unsigned
1470 * conversion
1471 * @since 1.8
1472 */
1473 public static long toUnsignedLong(int x) {
1474 return ((long) x) & 0xffffffffL;
1475 }
1476
1477 /**
1478 * Returns the unsigned quotient of dividing the first argument by
1479 * the second where each argument and the result is interpreted as
1480 * an unsigned value.
1481 *
1482 * <p>Note that in two's complement arithmetic, the three other
1483 * basic arithmetic operations of add, subtract, and multiply are
1484 * bit-wise identical if the two operands are regarded as both
1485 * being signed or both being unsigned. Therefore separate {@code
1486 * addUnsigned}, etc. methods are not provided.
1487 *
1488 * @param dividend the value to be divided
1489 * @param divisor the value doing the dividing
1490 * @return the unsigned quotient of the first argument divided by
1491 * the second argument
1492 * @see #remainderUnsigned
1493 * @since 1.8
1494 */
1495 @IntrinsicCandidate
1496 public static int divideUnsigned(int dividend, int divisor) {
1497 // In lieu of tricky code, for now just use long arithmetic.
1498 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor));
1499 }
1500
1501 /**
1502 * Returns the unsigned remainder from dividing the first argument
1503 * by the second where each argument and the result is interpreted
1504 * as an unsigned value.
1505 *
1506 * @param dividend the value to be divided
1507 * @param divisor the value doing the dividing
1508 * @return the unsigned remainder of the first argument divided by
1509 * the second argument
1510 * @see #divideUnsigned
1511 * @since 1.8
1512 */
1513 @IntrinsicCandidate
1514 public static int remainderUnsigned(int dividend, int divisor) {
1515 // In lieu of tricky code, for now just use long arithmetic.
1516 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor));
1517 }
1518
1519
1520 // Bit twiddling
1521
1522 /**
1523 * The number of bits used to represent an {@code int} value in two's
1524 * complement binary form.
1525 *
1526 * @since 1.5
1527 */
1528 @Native public static final int SIZE = 32;
1529
1530 /**
1531 * The number of bytes used to represent an {@code int} value in two's
1532 * complement binary form.
1533 *
1534 * @since 1.8
1535 */
1536 public static final int BYTES = SIZE / Byte.SIZE;
1537
1538 /**
1539 * Returns an {@code int} value with at most a single one-bit, in the
1540 * position of the highest-order ("leftmost") one-bit in the specified
1541 * {@code int} value. Returns zero if the specified value has no
1542 * one-bits in its two's complement binary representation, that is, if it
1543 * is equal to zero.
1544 *
1545 * @param i the value whose highest one bit is to be computed
1546 * @return an {@code int} value with a single one-bit, in the position
1547 * of the highest-order one-bit in the specified value, or zero if
1548 * the specified value is itself equal to zero.
1549 * @since 1.5
1550 */
1551 public static int highestOneBit(int i) {
1552 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1553 }
1554
1555 /**
1556 * Returns an {@code int} value with at most a single one-bit, in the
1557 * position of the lowest-order ("rightmost") one-bit in the specified
1558 * {@code int} value. Returns zero if the specified value has no
1559 * one-bits in its two's complement binary representation, that is, if it
1560 * is equal to zero.
1561 *
1562 * @param i the value whose lowest one bit is to be computed
1563 * @return an {@code int} value with a single one-bit, in the position
1564 * of the lowest-order one-bit in the specified value, or zero if
1565 * the specified value is itself equal to zero.
1566 * @since 1.5
1567 */
1568 public static int lowestOneBit(int i) {
1569 // HD, Section 2-1
1570 return i & -i;
1571 }
1572
1573 /**
1574 * Returns the number of zero bits preceding the highest-order
1575 * ("leftmost") one-bit in the two's complement binary representation
1576 * of the specified {@code int} value. Returns 32 if the
1577 * specified value has no one-bits in its two's complement representation,
1578 * in other words if it is equal to zero.
1579 *
1580 * <p>Note that this method is closely related to the logarithm base 2.
1581 * For all positive {@code int} values x:
1582 * <ul>
1583 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1584 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1585 * </ul>
1586 *
1587 * @param i the value whose number of leading zeros is to be computed
1588 * @return the number of zero bits preceding the highest-order
1589 * ("leftmost") one-bit in the two's complement binary representation
1590 * of the specified {@code int} value, or 32 if the value
1591 * is equal to zero.
1592 * @since 1.5
1593 */
1594 @IntrinsicCandidate
1595 public static int numberOfLeadingZeros(int i) {
1596 // HD, Count leading 0's
1597 if (i <= 0)
1598 return i == 0 ? 32 : 0;
1599 int n = 31;
1600 if (i >= 1 << 16) { n -= 16; i >>>= 16; }
1601 if (i >= 1 << 8) { n -= 8; i >>>= 8; }
1602 if (i >= 1 << 4) { n -= 4; i >>>= 4; }
1603 if (i >= 1 << 2) { n -= 2; i >>>= 2; }
1604 return n - (i >>> 1);
1605 }
1606
1607 /**
1608 * Returns the number of zero bits following the lowest-order ("rightmost")
1609 * one-bit in the two's complement binary representation of the specified
1610 * {@code int} value. Returns 32 if the specified value has no
1611 * one-bits in its two's complement representation, in other words if it is
1612 * equal to zero.
1613 *
1614 * @param i the value whose number of trailing zeros is to be computed
1615 * @return the number of zero bits following the lowest-order ("rightmost")
1616 * one-bit in the two's complement binary representation of the
1617 * specified {@code int} value, or 32 if the value is equal
1618 * to zero.
1619 * @since 1.5
1620 */
1621 @IntrinsicCandidate
1622 public static int numberOfTrailingZeros(int i) {
1623 // HD, Count trailing 0's
1624 i = ~i & (i - 1);
1625 if (i <= 0) return i & 32;
1626 int n = 1;
1627 if (i > 1 << 16) { n += 16; i >>>= 16; }
1628 if (i > 1 << 8) { n += 8; i >>>= 8; }
1629 if (i > 1 << 4) { n += 4; i >>>= 4; }
1630 if (i > 1 << 2) { n += 2; i >>>= 2; }
1631 return n + (i >>> 1);
1632 }
1633
1634 /**
1635 * Returns the number of one-bits in the two's complement binary
1636 * representation of the specified {@code int} value. This function is
1637 * sometimes referred to as the <i>population count</i>.
1638 *
1639 * @param i the value whose bits are to be counted
1640 * @return the number of one-bits in the two's complement binary
1641 * representation of the specified {@code int} value.
1642 * @since 1.5
1643 */
1644 @IntrinsicCandidate
1645 public static int bitCount(int i) {
1646 // HD, Figure 5-2
1647 i = i - ((i >>> 1) & 0x55555555);
1648 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1649 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1650 i = i + (i >>> 8);
1651 i = i + (i >>> 16);
1652 return i & 0x3f;
1653 }
1654
1655 /**
1656 * Returns the value obtained by rotating the two's complement binary
1657 * representation of the specified {@code int} value left by the
1658 * specified number of bits. (Bits shifted out of the left hand, or
1659 * high-order, side reenter on the right, or low-order.)
1660 *
1661 * <p>Note that left rotation with a negative distance is equivalent to
1662 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1663 * distance)}. Note also that rotation by any multiple of 32 is a
1664 * no-op, so all but the last five bits of the rotation distance can be
1665 * ignored, even if the distance is negative: {@code rotateLeft(val,
1666 * distance) == rotateLeft(val, distance & 0x1F)}.
1667 *
1668 * @param i the value whose bits are to be rotated left
1669 * @param distance the number of bit positions to rotate left
1670 * @return the value obtained by rotating the two's complement binary
1671 * representation of the specified {@code int} value left by the
1672 * specified number of bits.
1673 * @since 1.5
1674 */
1675 public static int rotateLeft(int i, int distance) {
1676 return (i << distance) | (i >>> -distance);
1677 }
1678
1679 /**
1680 * Returns the value obtained by rotating the two's complement binary
1681 * representation of the specified {@code int} value right by the
1682 * specified number of bits. (Bits shifted out of the right hand, or
1683 * low-order, side reenter on the left, or high-order.)
1684 *
1685 * <p>Note that right rotation with a negative distance is equivalent to
1686 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1687 * distance)}. Note also that rotation by any multiple of 32 is a
1688 * no-op, so all but the last five bits of the rotation distance can be
1689 * ignored, even if the distance is negative: {@code rotateRight(val,
1690 * distance) == rotateRight(val, distance & 0x1F)}.
1691 *
1692 * @param i the value whose bits are to be rotated right
1693 * @param distance the number of bit positions to rotate right
1694 * @return the value obtained by rotating the two's complement binary
1695 * representation of the specified {@code int} value right by the
1696 * specified number of bits.
1697 * @since 1.5
1698 */
1699 public static int rotateRight(int i, int distance) {
1700 return (i >>> distance) | (i << -distance);
1701 }
1702
1703 /**
1704 * Returns the value obtained by reversing the order of the bits in the
1705 * two's complement binary representation of the specified {@code int}
1706 * value.
1707 *
1708 * @param i the value to be reversed
1709 * @return the value obtained by reversing order of the bits in the
1710 * specified {@code int} value.
1711 * @since 1.5
1712 */
1713 @IntrinsicCandidate
1714 public static int reverse(int i) {
1715 // HD, Figure 7-1
1716 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1717 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1718 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1719
1720 return reverseBytes(i);
1721 }
1722
1723 /**
1724 * Returns the value obtained by compressing the bits of the
1725 * specified {@code int} value, {@code i}, in accordance with
1726 * the specified bit mask.
1727 * <p>
1728 * For each one-bit value {@code mb} of the mask, from least
1729 * significant to most significant, the bit value of {@code i} at
1730 * the same bit location as {@code mb} is assigned to the compressed
1731 * value contiguously starting from the least significant bit location.
1732 * All the upper remaining bits of the compressed value are set
1733 * to zero.
1734 *
1735 * @apiNote
1736 * Consider the simple case of compressing the digits of a hexadecimal
1737 * value:
1738 * {@snippet lang="java" :
1739 * // Compressing drink to food
1740 * compress(0xCAFEBABE, 0xFF00FFF0) == 0xCABAB
1741 * }
1742 * Starting from the least significant hexadecimal digit at position 0
1743 * from the right, the mask {@code 0xFF00FFF0} selects hexadecimal digits
1744 * at positions 1, 2, 3, 6 and 7 of {@code 0xCAFEBABE}. The selected digits
1745 * occur in the resulting compressed value contiguously from digit position
1746 * 0 in the same order.
1747 * <p>
1748 * The following identities all return {@code true} and are helpful to
1749 * understand the behaviour of {@code compress}:
1750 * {@snippet lang="java" :
1751 * // Returns 1 if the bit at position n is one
1752 * compress(x, 1 << n) == (x >> n & 1)
1753 *
1754 * // Logical shift right
1755 * compress(x, -1 << n) == x >>> n
1756 *
1757 * // Any bits not covered by the mask are ignored
1758 * compress(x, m) == compress(x & m, m)
1759 *
1760 * // Compressing a value by itself
1761 * compress(m, m) == (m == -1 || m == 0) ? m : (1 << bitCount(m)) - 1
1762 *
1763 * // Expanding then compressing with the same mask
1764 * compress(expand(x, m), m) == x & compress(m, m)
1765 * }
1766 * <p>
1767 * The Sheep And Goats (SAG) operation (see Hacker's Delight, Second Edition, section 7.7)
1768 * can be implemented as follows:
1769 * {@snippet lang="java" :
1770 * int compressLeft(int i, int mask) {
1771 * // This implementation follows the description in Hacker's Delight which
1772 * // is informative. A more optimal implementation is:
1773 * // Integer.compress(i, mask) << -Integer.bitCount(mask)
1774 * return Integer.reverse(
1775 * Integer.compress(Integer.reverse(i), Integer.reverse(mask)));
1776 * }
1777 *
1778 * int sag(int i, int mask) {
1779 * return compressLeft(i, mask) | Integer.compress(i, ~mask);
1780 * }
1781 *
1782 * // Separate the sheep from the goats
1783 * sag(0xCAFEBABE, 0xFF00FFF0) == 0xCABABFEE
1784 * }
1785 *
1786 * @param i the value whose bits are to be compressed
1787 * @param mask the bit mask
1788 * @return the compressed value
1789 * @see #expand
1790 * @since 19
1791 */
1792 @IntrinsicCandidate
1793 public static int compress(int i, int mask) {
1794 // See Hacker's Delight (2nd ed) section 7.4 Compress, or Generalized Extract
1795
1796 i = i & mask; // Clear irrelevant bits
1797 int maskCount = ~mask << 1; // Count 0's to right
1798
1799 for (int j = 0; j < 5; j++) {
1800 // Parallel prefix
1801 // Mask prefix identifies bits of the mask that have an odd number of 0's to the right
1802 int maskPrefix = parallelSuffix(maskCount);
1803 // Bits to move
1804 int maskMove = maskPrefix & mask;
1805 // Compress mask
1806 mask = (mask ^ maskMove) | (maskMove >>> (1 << j));
1807 // Bits of i to be moved
1808 int t = i & maskMove;
1809 // Compress i
1810 i = (i ^ t) | (t >>> (1 << j));
1811 // Adjust the mask count by identifying bits that have 0 to the right
1812 maskCount = maskCount & ~maskPrefix;
1813 }
1814 return i;
1815 }
1816
1817 /**
1818 * Returns the value obtained by expanding the bits of the
1819 * specified {@code int} value, {@code i}, in accordance with
1820 * the specified bit mask.
1821 * <p>
1822 * For each one-bit value {@code mb} of the mask, from least
1823 * significant to most significant, the next contiguous bit value
1824 * of {@code i} starting at the least significant bit is assigned
1825 * to the expanded value at the same bit location as {@code mb}.
1826 * All other remaining bits of the expanded value are set to zero.
1827 *
1828 * @apiNote
1829 * Consider the simple case of expanding the digits of a hexadecimal
1830 * value:
1831 * {@snippet lang="java" :
1832 * expand(0x0000CABAB, 0xFF00FFF0) == 0xCA00BAB0
1833 * }
1834 * Starting from the least significant hexadecimal digit at position 0
1835 * from the right, the mask {@code 0xFF00FFF0} selects the first five
1836 * hexadecimal digits of {@code 0x0000CABAB}. The selected digits occur
1837 * in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.
1838 * <p>
1839 * The following identities all return {@code true} and are helpful to
1840 * understand the behaviour of {@code expand}:
1841 * {@snippet lang="java" :
1842 * // Logically shift right the bit at position 0
1843 * expand(x, 1 << n) == (x & 1) << n
1844 *
1845 * // Logically shift right
1846 * expand(x, -1 << n) == x << n
1847 *
1848 * // Expanding all bits returns the mask
1849 * expand(-1, m) == m
1850 *
1851 * // Any bits not covered by the mask are ignored
1852 * expand(x, m) == expand(x, m) & m
1853 *
1854 * // Compressing then expanding with the same mask
1855 * expand(compress(x, m), m) == x & m
1856 * }
1857 * <p>
1858 * The select operation for determining the position of the one-bit with
1859 * index {@code n} in a {@code int} value can be implemented as follows:
1860 * {@snippet lang="java" :
1861 * int select(int i, int n) {
1862 * // the one-bit in i (the mask) with index n
1863 * int nthBit = Integer.expand(1 << n, i);
1864 * // the bit position of the one-bit with index n
1865 * return Integer.numberOfTrailingZeros(nthBit);
1866 * }
1867 *
1868 * // The one-bit with index 0 is at bit position 1
1869 * select(0b10101010_10101010, 0) == 1
1870 * // The one-bit with index 3 is at bit position 7
1871 * select(0b10101010_10101010, 3) == 7
1872 * }
1873 *
1874 * @param i the value whose bits are to be expanded
1875 * @param mask the bit mask
1876 * @return the expanded value
1877 * @see #compress
1878 * @since 19
1879 */
1880 @IntrinsicCandidate
1881 public static int expand(int i, int mask) {
1882 // Save original mask
1883 int originalMask = mask;
1884 // Count 0's to right
1885 int maskCount = ~mask << 1;
1886 int maskPrefix = parallelSuffix(maskCount);
1887 // Bits to move
1888 int maskMove1 = maskPrefix & mask;
1889 // Compress mask
1890 mask = (mask ^ maskMove1) | (maskMove1 >>> (1 << 0));
1891 maskCount = maskCount & ~maskPrefix;
1892
1893 maskPrefix = parallelSuffix(maskCount);
1894 // Bits to move
1895 int maskMove2 = maskPrefix & mask;
1896 // Compress mask
1897 mask = (mask ^ maskMove2) | (maskMove2 >>> (1 << 1));
1898 maskCount = maskCount & ~maskPrefix;
1899
1900 maskPrefix = parallelSuffix(maskCount);
1901 // Bits to move
1902 int maskMove3 = maskPrefix & mask;
1903 // Compress mask
1904 mask = (mask ^ maskMove3) | (maskMove3 >>> (1 << 2));
1905 maskCount = maskCount & ~maskPrefix;
1906
1907 maskPrefix = parallelSuffix(maskCount);
1908 // Bits to move
1909 int maskMove4 = maskPrefix & mask;
1910 // Compress mask
1911 mask = (mask ^ maskMove4) | (maskMove4 >>> (1 << 3));
1912 maskCount = maskCount & ~maskPrefix;
1913
1914 maskPrefix = parallelSuffix(maskCount);
1915 // Bits to move
1916 int maskMove5 = maskPrefix & mask;
1917
1918 int t = i << (1 << 4);
1919 i = (i & ~maskMove5) | (t & maskMove5);
1920 t = i << (1 << 3);
1921 i = (i & ~maskMove4) | (t & maskMove4);
1922 t = i << (1 << 2);
1923 i = (i & ~maskMove3) | (t & maskMove3);
1924 t = i << (1 << 1);
1925 i = (i & ~maskMove2) | (t & maskMove2);
1926 t = i << (1 << 0);
1927 i = (i & ~maskMove1) | (t & maskMove1);
1928
1929 // Clear irrelevant bits
1930 return i & originalMask;
1931 }
1932
1933 @ForceInline
1934 private static int parallelSuffix(int maskCount) {
1935 int maskPrefix = maskCount ^ (maskCount << 1);
1936 maskPrefix = maskPrefix ^ (maskPrefix << 2);
1937 maskPrefix = maskPrefix ^ (maskPrefix << 4);
1938 maskPrefix = maskPrefix ^ (maskPrefix << 8);
1939 maskPrefix = maskPrefix ^ (maskPrefix << 16);
1940 return maskPrefix;
1941 }
1942
1943 /**
1944 * Returns the signum function of the specified {@code int} value. (The
1945 * return value is -1 if the specified value is negative; 0 if the
1946 * specified value is zero; and 1 if the specified value is positive.)
1947 *
1948 * @param i the value whose signum is to be computed
1949 * @return the signum function of the specified {@code int} value.
1950 * @since 1.5
1951 */
1952 public static int signum(int i) {
1953 // HD, Section 2-7
1954 return (i >> 31) | (-i >>> 31);
1955 }
1956
1957 /**
1958 * Returns the value obtained by reversing the order of the bytes in the
1959 * two's complement representation of the specified {@code int} value.
1960 *
1961 * @param i the value whose bytes are to be reversed
1962 * @return the value obtained by reversing the bytes in the specified
1963 * {@code int} value.
1964 * @since 1.5
1965 */
1966 @IntrinsicCandidate
1967 public static int reverseBytes(int i) {
1968 return (i << 24) |
1969 ((i & 0xff00) << 8) |
1970 ((i >>> 8) & 0xff00) |
1971 (i >>> 24);
1972 }
1973
1974 /**
1975 * Adds two integers together as per the + operator.
1976 *
1977 * @param a the first operand
1978 * @param b the second operand
1979 * @return the sum of {@code a} and {@code b}
1980 * @see java.util.function.BinaryOperator
1981 * @since 1.8
1982 */
1983 public static int sum(int a, int b) {
1984 return a + b;
1985 }
1986
1987 /**
1988 * Returns the greater of two {@code int} values
1989 * as if by calling {@link Math#max(int, int) Math.max}.
1990 *
1991 * @param a the first operand
1992 * @param b the second operand
1993 * @return the greater of {@code a} and {@code b}
1994 * @see java.util.function.BinaryOperator
1995 * @since 1.8
1996 */
1997 public static int max(int a, int b) {
1998 return Math.max(a, b);
1999 }
2000
2001 /**
2002 * Returns the smaller of two {@code int} values
2003 * as if by calling {@link Math#min(int, int) Math.min}.
2004 *
2005 * @param a the first operand
2006 * @param b the second operand
2007 * @return the smaller of {@code a} and {@code b}
2008 * @see java.util.function.BinaryOperator
2009 * @since 1.8
2010 */
2011 public static int min(int a, int b) {
2012 return Math.min(a, b);
2013 }
2014
2015 /**
2016 * Returns an {@link Optional} containing the nominal descriptor for this
2017 * instance, which is the instance itself.
2018 *
2019 * @return an {@link Optional} describing the {@linkplain Integer} instance
2020 * @since 12
2021 */
2022 @Override
2023 public Optional<Integer> describeConstable() {
2024 return Optional.of(this);
2025 }
2026
2027 /**
2028 * Resolves this instance as a {@link ConstantDesc}, the result of which is
2029 * the instance itself.
2030 *
2031 * @param lookup ignored
2032 * @return the {@linkplain Integer} instance
2033 * @since 12
2034 */
2035 @Override
2036 public Integer resolveConstantDesc(MethodHandles.Lookup lookup) {
2037 return this;
2038 }
2039
2040 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2041 @java.io.Serial
2042 @Native private static final long serialVersionUID = 1360826667806852920L;
2043 }