1 /*
2 * Copyright (c) 1994, 2024, 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.VM;
30 import jdk.internal.util.DecimalDigits;
31 import jdk.internal.value.DeserializeConstructor;
32 import jdk.internal.vm.annotation.ForceInline;
33 import jdk.internal.vm.annotation.IntrinsicCandidate;
34 import jdk.internal.vm.annotation.Stable;
35
36 import java.lang.annotation.Native;
37 import java.lang.constant.Constable;
38 import java.lang.constant.ConstantDesc;
39 import java.lang.invoke.MethodHandles;
40 import java.util.Objects;
41 import java.util.Optional;
42
43 import static java.lang.Character.digit;
44 import static java.lang.String.COMPACT_STRINGS;
45 import static java.lang.String.LATIN1;
46 import static java.lang.String.UTF16;
47
48 /**
49 * The {@code Integer} class is the {@linkplain
50 * java.lang##wrapperClass wrapper class} for values of the primitive
51 * type {@code int}. An object of type {@code Integer} contains a
52 * single field whose type is {@code int}.
53 *
54 * <p>In addition, this class provides several methods for converting
55 * an {@code int} to a {@code String} and a {@code String} to an
56 * {@code int}, as well as other constants and methods useful when
57 * dealing with an {@code int}.
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
61 * {@linkplain #equals(Object) equal} as interchangeable and should not
62 * use instances for synchronization, or unpredictable behavior may
63 * occur. For example, in a future release, synchronization may fail.
64 *
65 * <p>Implementation note: The implementations of the "bit twiddling"
66 * methods (such as {@link #highestOneBit(int) highestOneBit} and
67 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
68 * based on material from Henry S. Warren, Jr.'s <cite>Hacker's
69 * Delight</cite>, (Addison Wesley, 2002) and <cite>Hacker's
70 * Delight, Second Edition</cite>, (Pearson Education, 2013).
71 *
72 * @author Lee Boynton
73 * @author Arthur van Hoff
74 * @author Josh Bloch
75 * @author Joseph D. Darcy
76 * @since 1.0
77 */
78 @jdk.internal.MigratedValueClass
79 @jdk.internal.ValueBased
80 public final class Integer extends Number
81 implements Comparable<Integer>, Constable, ConstantDesc {
82 /**
83 * A constant holding the minimum value an {@code int} can
84 * have, -2<sup>31</sup>.
85 */
86 @Native public static final int MIN_VALUE = 0x80000000;
87
88 /**
89 * A constant holding the maximum value an {@code int} can
90 * have, 2<sup>31</sup>-1.
91 */
92 @Native public static final int MAX_VALUE = 0x7fffffff;
93
94 /**
95 * The {@code Class} instance representing the primitive type
96 * {@code int}.
97 *
98 * @since 1.1
99 */
100 public static final Class<Integer> TYPE = Class.getPrimitiveClass("int");
101
102 /**
103 * All possible chars for representing a number as a String
104 */
105 static final char[] digits = {
106 '0' , '1' , '2' , '3' , '4' , '5' ,
107 '6' , '7' , '8' , '9' , 'a' , 'b' ,
108 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
109 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
110 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
111 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
112 };
113
114 /**
115 * Returns a string representation of the first argument in the
116 * radix specified by the second argument.
117 *
118 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
119 * or larger than {@code Character.MAX_RADIX}, then the radix
120 * {@code 10} is used instead.
121 *
122 * <p>If the first argument is negative, the first element of the
123 * result is the ASCII minus character {@code '-'}
124 * ({@code '\u005Cu002D'}). If the first argument is not
125 * negative, no sign character appears in the result.
126 *
127 * <p>The remaining characters of the result represent the magnitude
128 * of the first argument. If the magnitude is zero, it is
129 * represented by a single zero character {@code '0'}
130 * ({@code '\u005Cu0030'}); otherwise, the first character of
131 * the representation of the magnitude will not be the zero
132 * character. The following ASCII characters are used as digits:
133 *
134 * <blockquote>
135 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
136 * </blockquote>
137 *
138 * These are {@code '\u005Cu0030'} through
139 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
140 * {@code '\u005Cu007A'}. If {@code radix} is
141 * <var>N</var>, then the first <var>N</var> of these characters
142 * are used as radix-<var>N</var> digits in the order shown. Thus,
143 * the digits for hexadecimal (radix 16) are
144 * {@code 0123456789abcdef}. If uppercase letters are
145 * desired, the {@link java.lang.String#toUpperCase()} method may
146 * be called on the result:
147 *
148 * <blockquote>
149 * {@code Integer.toString(n, 16).toUpperCase()}
150 * </blockquote>
151 *
152 * @param i an integer to be converted to a string.
153 * @param radix the radix to use in the string representation.
154 * @return a string representation of the argument in the specified radix.
155 * @see java.lang.Character#MAX_RADIX
156 * @see java.lang.Character#MIN_RADIX
157 */
158 public static String toString(int i, int radix) {
159 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
160 radix = 10;
161
162 /* Use the faster version */
163 if (radix == 10) {
164 return toString(i);
165 }
166
167 if (COMPACT_STRINGS) {
168 byte[] buf = new byte[33];
169 boolean negative = (i < 0);
170 int charPos = 32;
171
172 if (!negative) {
173 i = -i;
174 }
175
176 while (i <= -radix) {
177 buf[charPos--] = (byte)digits[-(i % radix)];
178 i = i / radix;
179 }
180 buf[charPos] = (byte)digits[-i];
181
182 if (negative) {
183 buf[--charPos] = '-';
184 }
185
186 return StringLatin1.newString(buf, charPos, (33 - charPos));
187 }
188 return toStringUTF16(i, radix);
189 }
190
191 private static String toStringUTF16(int i, int radix) {
192 byte[] buf = new byte[33 * 2];
193 boolean negative = (i < 0);
194 int charPos = 32;
195 if (!negative) {
196 i = -i;
197 }
198 while (i <= -radix) {
199 StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
200 i = i / radix;
201 }
202 StringUTF16.putChar(buf, charPos, digits[-i]);
203
204 if (negative) {
205 StringUTF16.putChar(buf, --charPos, '-');
206 }
207 return StringUTF16.newString(buf, charPos, (33 - charPos));
208 }
209
210 /**
211 * Returns a string representation of the first argument as an
212 * unsigned integer value in the radix specified by the second
213 * argument.
214 *
215 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
216 * or larger than {@code Character.MAX_RADIX}, then the radix
217 * {@code 10} is used instead.
218 *
219 * <p>Note that since the first argument is treated as an unsigned
220 * value, no leading sign character is printed.
221 *
222 * <p>If the magnitude is zero, it is represented by a single zero
223 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
224 * the first character of the representation of the magnitude will
225 * not be the zero character.
226 *
227 * <p>The behavior of radixes and the characters used as digits
228 * are the same as {@link #toString(int, int) toString}.
229 *
230 * @param i an integer to be converted to an unsigned string.
231 * @param radix the radix to use in the string representation.
232 * @return an unsigned string representation of the argument in the specified radix.
233 * @see #toString(int, int)
234 * @since 1.8
235 */
236 public static String toUnsignedString(int i, int radix) {
237 return Long.toUnsignedString(toUnsignedLong(i), radix);
238 }
239
240 /**
241 * Returns a string representation of the integer argument as an
242 * unsigned integer in base 16.
243 *
244 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
245 * if the argument is negative; otherwise, it is equal to the
246 * argument. This value is converted to a string of ASCII digits
247 * in hexadecimal (base 16) with no extra leading
248 * {@code 0}s.
249 *
250 * <p>The value of the argument can be recovered from the returned
251 * string {@code s} by calling {@link
252 * Integer#parseUnsignedInt(String, int)
253 * Integer.parseUnsignedInt(s, 16)}.
254 *
255 * <p>If the unsigned magnitude is zero, it is represented by a
256 * single zero character {@code '0'} ({@code '\u005Cu0030'});
257 * otherwise, the first character of the representation of the
258 * unsigned magnitude will not be the zero character. The
259 * following characters are used as hexadecimal digits:
260 *
261 * <blockquote>
262 * {@code 0123456789abcdef}
263 * </blockquote>
264 *
265 * These are the characters {@code '\u005Cu0030'} through
266 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
267 * {@code '\u005Cu0066'}. If uppercase letters are
268 * desired, the {@link java.lang.String#toUpperCase()} method may
269 * be called on the result:
270 *
271 * <blockquote>
272 * {@code Integer.toHexString(n).toUpperCase()}
273 * </blockquote>
274 *
275 * @apiNote
276 * The {@link java.util.HexFormat} class provides formatting and parsing
277 * of byte arrays and primitives to return a string or adding to an {@link Appendable}.
278 * {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
279 * with leading zeros and for byte arrays includes for each byte
280 * a delimiter, prefix, and suffix.
281 *
282 * @param i an integer to be converted to a string.
283 * @return the string representation of the unsigned integer value
284 * represented by the argument in hexadecimal (base 16).
285 * @see java.util.HexFormat
286 * @see #parseUnsignedInt(String, int)
287 * @see #toUnsignedString(int, int)
288 * @since 1.0.2
289 */
290 public static String toHexString(int i) {
291 return toUnsignedString0(i, 4);
292 }
293
294 /**
295 * Returns a string representation of the integer argument as an
296 * unsigned integer in base 8.
297 *
298 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
299 * if the argument is negative; otherwise, it is equal to the
300 * argument. This value is converted to a string of ASCII digits
301 * in octal (base 8) with no extra leading {@code 0}s.
302 *
303 * <p>The value of the argument can be recovered from the returned
304 * string {@code s} by calling {@link
305 * Integer#parseUnsignedInt(String, int)
306 * Integer.parseUnsignedInt(s, 8)}.
307 *
308 * <p>If the unsigned magnitude is zero, it is represented by a
309 * single zero character {@code '0'} ({@code '\u005Cu0030'});
310 * otherwise, the first character of the representation of the
311 * unsigned magnitude will not be the zero character. The
312 * following characters are used as octal digits:
313 *
314 * <blockquote>
315 * {@code 01234567}
316 * </blockquote>
317 *
318 * These are the characters {@code '\u005Cu0030'} through
319 * {@code '\u005Cu0037'}.
320 *
321 * @param i an integer to be converted to a string.
322 * @return the string representation of the unsigned integer value
323 * represented by the argument in octal (base 8).
324 * @see #parseUnsignedInt(String, int)
325 * @see #toUnsignedString(int, int)
326 * @since 1.0.2
327 */
328 public static String toOctalString(int i) {
329 return toUnsignedString0(i, 3);
330 }
331
332 /**
333 * Returns a string representation of the integer argument as an
334 * unsigned integer in base 2.
335 *
336 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
337 * if the argument is negative; otherwise it is equal to the
338 * argument. This value is converted to a string of ASCII digits
339 * in binary (base 2) with no extra leading {@code 0}s.
340 *
341 * <p>The value of the argument can be recovered from the returned
342 * string {@code s} by calling {@link
343 * Integer#parseUnsignedInt(String, int)
344 * Integer.parseUnsignedInt(s, 2)}.
345 *
346 * <p>If the unsigned magnitude is zero, it is represented by a
347 * single zero character {@code '0'} ({@code '\u005Cu0030'});
348 * otherwise, the first character of the representation of the
349 * unsigned magnitude will not be the zero character. The
350 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
351 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
352 *
353 * @param i an integer to be converted to a string.
354 * @return the string representation of the unsigned integer value
355 * represented by the argument in binary (base 2).
356 * @see #parseUnsignedInt(String, int)
357 * @see #toUnsignedString(int, int)
358 * @since 1.0.2
359 */
360 public static String toBinaryString(int i) {
361 return toUnsignedString0(i, 1);
362 }
363
364 /**
365 * Convert the integer to an unsigned number.
366 */
367 private static String toUnsignedString0(int val, int shift) {
368 // assert shift > 0 && shift <=5 : "Illegal shift value";
369 int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
370 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
371 if (COMPACT_STRINGS) {
372 byte[] buf = new byte[chars];
373 formatUnsignedInt(val, shift, buf, chars);
374 return new String(buf, LATIN1);
375 } else {
376 byte[] buf = new byte[chars * 2];
377 formatUnsignedIntUTF16(val, shift, buf, chars);
378 return new String(buf, UTF16);
379 }
380 }
381
382 /**
383 * Format an {@code int} (treated as unsigned) into a byte buffer (LATIN1 version). If
384 * {@code len} exceeds the formatted ASCII representation of {@code val},
385 * {@code buf} will be padded with leading zeroes.
386 *
387 * @param val the unsigned int to format
388 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
389 * @param buf the byte buffer to write to
390 * @param len the number of characters to write
391 */
392 private static void formatUnsignedInt(int val, int shift, byte[] buf, int len) {
393 int charPos = len;
394 int radix = 1 << shift;
395 int mask = radix - 1;
396 do {
397 buf[--charPos] = (byte)Integer.digits[val & mask];
398 val >>>= shift;
399 } while (charPos > 0);
400 }
401
402 /**
403 * Format an {@code int} (treated as unsigned) into a byte buffer (UTF16 version). If
404 * {@code len} exceeds the formatted ASCII representation of {@code val},
405 * {@code buf} will be padded with leading zeroes.
406 *
407 * @param val the unsigned int to format
408 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
409 * @param buf the byte buffer to write to
410 * @param len the number of characters to write
411 */
412 private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int len) {
413 int charPos = len;
414 int radix = 1 << shift;
415 int mask = radix - 1;
416 do {
417 StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
418 val >>>= shift;
419 } while (charPos > 0);
420 }
421
422 /**
423 * Returns a {@code String} object representing the
424 * specified integer. The argument is converted to signed decimal
425 * representation and returned as a string, exactly as if the
426 * argument and radix 10 were given as arguments to the {@link
427 * #toString(int, int)} method.
428 *
429 * @param i an integer to be converted.
430 * @return a string representation of the argument in base 10.
431 */
432 @IntrinsicCandidate
433 public static String toString(int i) {
434 int size = DecimalDigits.stringSize(i);
435 if (COMPACT_STRINGS) {
436 byte[] buf = new byte[size];
437 StringLatin1.getChars(i, size, buf);
438 return new String(buf, LATIN1);
439 } else {
440 byte[] buf = new byte[size * 2];
441 StringUTF16.getChars(i, size, buf);
442 return new String(buf, UTF16);
443 }
444 }
445
446 /**
447 * Returns a string representation of the argument as an unsigned
448 * decimal value.
449 *
450 * The argument is converted to unsigned decimal representation
451 * and returned as a string exactly as if the argument and radix
452 * 10 were given as arguments to the {@link #toUnsignedString(int,
453 * int)} method.
454 *
455 * @param i an integer to be converted to an unsigned string.
456 * @return an unsigned string representation of the argument.
457 * @see #toUnsignedString(int, int)
458 * @since 1.8
459 */
460 public static String toUnsignedString(int i) {
461 return Long.toString(toUnsignedLong(i));
462 }
463
464 /**
465 * Parses the string argument as a signed integer in the radix
466 * specified by the second argument. The characters in the string
467 * must all be digits of the specified radix (as determined by
468 * whether {@link java.lang.Character#digit(char, int)} returns a
469 * nonnegative value), except that the first character may be an
470 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
471 * indicate a negative value or an ASCII plus sign {@code '+'}
472 * ({@code '\u005Cu002B'}) to indicate a positive value. The
473 * resulting integer value is returned.
474 *
475 * <p>An exception of type {@code NumberFormatException} is
476 * thrown if any of the following situations occurs:
477 * <ul>
478 * <li>The first argument is {@code null} or is a string of
479 * length zero.
480 *
481 * <li>The radix is either smaller than
482 * {@link java.lang.Character#MIN_RADIX} or
483 * larger than {@link java.lang.Character#MAX_RADIX}.
484 *
485 * <li>Any character of the string is not a digit of the specified
486 * radix, except that the first character may be a minus sign
487 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign
488 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
489 * string is longer than length 1.
490 *
491 * <li>The value represented by the string is not a value of type
492 * {@code int}.
493 * </ul>
494 *
495 * <p>Examples:
496 * <blockquote><pre>
497 * parseInt("0", 10) returns 0
498 * parseInt("473", 10) returns 473
499 * parseInt("+42", 10) returns 42
500 * parseInt("-0", 10) returns 0
501 * parseInt("-FF", 16) returns -255
502 * parseInt("1100110", 2) returns 102
503 * parseInt("2147483647", 10) returns 2147483647
504 * parseInt("-2147483648", 10) returns -2147483648
505 * parseInt("2147483648", 10) throws a NumberFormatException
506 * parseInt("99", 8) throws a NumberFormatException
507 * parseInt("Kona", 10) throws a NumberFormatException
508 * parseInt("Kona", 27) returns 411787
509 * </pre></blockquote>
510 *
511 * @param s the {@code String} containing the integer
512 * representation to be parsed
513 * @param radix the radix to be used while parsing {@code s}.
514 * @return the integer represented by the string argument in the
515 * specified radix.
516 * @throws NumberFormatException if the {@code String}
517 * does not contain a parsable {@code int}.
518 */
519 public static int parseInt(String s, int radix)
520 throws NumberFormatException {
521 /*
522 * WARNING: This method may be invoked early during VM initialization
523 * before IntegerCache is initialized. Care must be taken to not use
524 * the valueOf method.
525 */
526
527 if (s == null) {
528 throw new NumberFormatException("Cannot parse null string");
529 }
530
531 if (radix < Character.MIN_RADIX) {
532 throw new NumberFormatException(String.format(
533 "radix %s less than Character.MIN_RADIX", radix));
534 }
535
536 if (radix > Character.MAX_RADIX) {
537 throw new NumberFormatException(String.format(
538 "radix %s greater than Character.MAX_RADIX", radix));
539 }
540
541 int len = s.length();
542 if (len == 0) {
543 throw NumberFormatException.forInputString("", radix);
544 }
545 int digit = ~0xFF;
546 int i = 0;
547 char firstChar = s.charAt(i++);
548 if (firstChar != '-' && firstChar != '+') {
549 digit = digit(firstChar, radix);
550 }
551 if (digit >= 0 || digit == ~0xFF && len > 1) {
552 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
553 int multmin = limit / radix;
554 int result = -(digit & 0xFF);
555 boolean inRange = true;
556 /* Accumulating negatively avoids surprises near MAX_VALUE */
557 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
558 && (inRange = result > multmin
559 || result == multmin && digit <= radix * multmin - limit)) {
560 result = radix * result - digit;
561 }
562 if (inRange && i == len && digit >= 0) {
563 return firstChar != '-' ? -result : result;
564 }
565 }
566 throw NumberFormatException.forInputString(s, radix);
567 }
568
569 /**
570 * Parses the {@link CharSequence} argument as a signed {@code int} in the
571 * specified {@code radix}, beginning at the specified {@code beginIndex}
572 * and extending to {@code endIndex - 1}.
573 *
574 * <p>The method does not take steps to guard against the
575 * {@code CharSequence} being mutated while parsing.
576 *
577 * @param s the {@code CharSequence} containing the {@code int}
578 * representation to be parsed
579 * @param beginIndex the beginning index, inclusive.
580 * @param endIndex the ending index, exclusive.
581 * @param radix the radix to be used while parsing {@code s}.
582 * @return the signed {@code int} represented by the subsequence in
583 * the specified radix.
584 * @throws NullPointerException if {@code s} is null.
585 * @throws IndexOutOfBoundsException if {@code beginIndex} is
586 * negative, or if {@code beginIndex} is greater than
587 * {@code endIndex} or if {@code endIndex} is greater than
588 * {@code s.length()}.
589 * @throws NumberFormatException if the {@code CharSequence} does not
590 * contain a parsable {@code int} in the specified
591 * {@code radix}, or if {@code radix} is either smaller than
592 * {@link java.lang.Character#MIN_RADIX} or larger than
593 * {@link java.lang.Character#MAX_RADIX}.
594 * @since 9
595 */
596 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
597 throws NumberFormatException {
598 Objects.requireNonNull(s);
599 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
600
601 if (radix < Character.MIN_RADIX) {
602 throw new NumberFormatException(String.format(
603 "radix %s less than Character.MIN_RADIX", radix));
604 }
605
606 if (radix > Character.MAX_RADIX) {
607 throw new NumberFormatException(String.format(
608 "radix %s greater than Character.MAX_RADIX", radix));
609 }
610
611 /*
612 * While s can be concurrently modified, it is ensured that each
613 * of its characters is read at most once, from lower to higher indices.
614 * This is obtained by reading them using the pattern s.charAt(i++),
615 * and by not updating i anywhere else.
616 */
617 if (beginIndex == endIndex) {
618 throw NumberFormatException.forInputString("", radix);
619 }
620 int digit = ~0xFF;
621 int i = beginIndex;
622 char firstChar = s.charAt(i++);
623 if (firstChar != '-' && firstChar != '+') {
624 digit = digit(firstChar, radix);
625 }
626 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
627 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
628 int multmin = limit / radix;
629 int result = -(digit & 0xFF);
630 boolean inRange = true;
631 /* Accumulating negatively avoids surprises near MAX_VALUE */
632 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
633 && (inRange = result > multmin
634 || result == multmin && digit <= radix * multmin - limit)) {
635 result = radix * result - digit;
636 }
637 if (inRange && i == endIndex && digit >= 0) {
638 return firstChar != '-' ? -result : result;
639 }
640 }
641 throw NumberFormatException.forCharSequence(s, beginIndex,
642 endIndex, i - (digit < -1 ? 0 : 1));
643 }
644
645 /**
646 * Parses the string argument as a signed decimal integer. The
647 * characters in the string must all be decimal digits, except
648 * that the first character may be an ASCII minus sign {@code '-'}
649 * ({@code '\u005Cu002D'}) to indicate a negative value or an
650 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
651 * indicate a positive value. The resulting integer value is
652 * returned, exactly as if the argument and the radix 10 were
653 * given as arguments to the {@link #parseInt(java.lang.String,
654 * int)} method.
655 *
656 * @param s a {@code String} containing the {@code int}
657 * representation to be parsed
658 * @return the integer value represented by the argument in decimal.
659 * @throws NumberFormatException if the string does not contain a
660 * parsable integer.
661 */
662 public static int parseInt(String s) throws NumberFormatException {
663 return parseInt(s, 10);
664 }
665
666 /**
667 * Parses the string argument as an unsigned integer in the radix
668 * specified by the second argument. An unsigned integer maps the
669 * values usually associated with negative numbers to positive
670 * numbers larger than {@code MAX_VALUE}.
671 *
672 * The characters in the string must all be digits of the
673 * specified radix (as determined by whether {@link
674 * java.lang.Character#digit(char, int)} returns a nonnegative
675 * value), except that the first character may be an ASCII plus
676 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
677 * integer value is returned.
678 *
679 * <p>An exception of type {@code NumberFormatException} is
680 * thrown if any of the following situations occurs:
681 * <ul>
682 * <li>The first argument is {@code null} or is a string of
683 * length zero.
684 *
685 * <li>The radix is either smaller than
686 * {@link java.lang.Character#MIN_RADIX} or
687 * larger than {@link java.lang.Character#MAX_RADIX}.
688 *
689 * <li>Any character of the string is not a digit of the specified
690 * radix, except that the first character may be a plus sign
691 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
692 * string is longer than length 1.
693 *
694 * <li>The value represented by the string is larger than the
695 * largest unsigned {@code int}, 2<sup>32</sup>-1.
696 *
697 * </ul>
698 *
699 *
700 * @param s the {@code String} containing the unsigned integer
701 * representation to be parsed
702 * @param radix the radix to be used while parsing {@code s}.
703 * @return the integer represented by the string argument in the
704 * specified radix.
705 * @throws NumberFormatException if the {@code String}
706 * does not contain a parsable {@code int}.
707 * @since 1.8
708 */
709 public static int parseUnsignedInt(String s, int radix)
710 throws NumberFormatException {
711 if (s == null) {
712 throw new NumberFormatException("Cannot parse null string");
713 }
714
715 if (radix < Character.MIN_RADIX) {
716 throw new NumberFormatException(String.format(
717 "radix %s less than Character.MIN_RADIX", radix));
718 }
719
720 if (radix > Character.MAX_RADIX) {
721 throw new NumberFormatException(String.format(
722 "radix %s greater than Character.MAX_RADIX", radix));
723 }
724
725 int len = s.length();
726 if (len == 0) {
727 throw NumberFormatException.forInputString(s, radix);
728 }
729 int i = 0;
730 char firstChar = s.charAt(i++);
731 if (firstChar == '-') {
732 throw new NumberFormatException(String.format(
733 "Illegal leading minus sign on unsigned string %s.", s));
734 }
735 int digit = ~0xFF;
736 if (firstChar != '+') {
737 digit = digit(firstChar, radix);
738 }
739 if (digit >= 0 || digit == ~0xFF && len > 1) {
740 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
741 int result = digit & 0xFF;
742 boolean inRange = true;
743 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
744 && (inRange = compareUnsigned(result, multmax) < 0
745 || result == multmax && digit < -radix * multmax)) {
746 result = radix * result + digit;
747 }
748 if (inRange && i == len && digit >= 0) {
749 return result;
750 }
751 }
752 if (digit < 0) {
753 throw NumberFormatException.forInputString(s, radix);
754 }
755 throw new NumberFormatException(String.format(
756 "String value %s exceeds range of unsigned int.", s));
757 }
758
759 /**
760 * Parses the {@link CharSequence} argument as an unsigned {@code int} in
761 * the specified {@code radix}, beginning at the specified
762 * {@code beginIndex} and extending to {@code endIndex - 1}.
763 *
764 * <p>The method does not take steps to guard against the
765 * {@code CharSequence} being mutated while parsing.
766 *
767 * @param s the {@code CharSequence} containing the unsigned
768 * {@code int} representation to be parsed
769 * @param beginIndex the beginning index, inclusive.
770 * @param endIndex the ending index, exclusive.
771 * @param radix the radix to be used while parsing {@code s}.
772 * @return the unsigned {@code int} represented by the subsequence in
773 * the specified radix.
774 * @throws NullPointerException if {@code s} is null.
775 * @throws IndexOutOfBoundsException if {@code beginIndex} is
776 * negative, or if {@code beginIndex} is greater than
777 * {@code endIndex} or if {@code endIndex} is greater than
778 * {@code s.length()}.
779 * @throws NumberFormatException if the {@code CharSequence} does not
780 * contain a parsable unsigned {@code int} in the specified
781 * {@code radix}, or if {@code radix} is either smaller than
782 * {@link java.lang.Character#MIN_RADIX} or larger than
783 * {@link java.lang.Character#MAX_RADIX}.
784 * @since 9
785 */
786 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
787 throws NumberFormatException {
788 Objects.requireNonNull(s);
789 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
790
791 if (radix < Character.MIN_RADIX) {
792 throw new NumberFormatException(String.format(
793 "radix %s less than Character.MIN_RADIX", radix));
794 }
795
796 if (radix > Character.MAX_RADIX) {
797 throw new NumberFormatException(String.format(
798 "radix %s greater than Character.MAX_RADIX", radix));
799 }
800
801 /*
802 * While s can be concurrently modified, it is ensured that each
803 * of its characters is read at most once, from lower to higher indices.
804 * This is obtained by reading them using the pattern s.charAt(i++),
805 * and by not updating i anywhere else.
806 */
807 if (beginIndex == endIndex) {
808 throw NumberFormatException.forInputString("", radix);
809 }
810 int i = beginIndex;
811 char firstChar = s.charAt(i++);
812 if (firstChar == '-') {
813 throw new NumberFormatException(
814 "Illegal leading minus sign on unsigned string " + s + ".");
815 }
816 int digit = ~0xFF;
817 if (firstChar != '+') {
818 digit = digit(firstChar, radix);
819 }
820 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
821 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
822 int result = digit & 0xFF;
823 boolean inRange = true;
824 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
825 && (inRange = compareUnsigned(result, multmax) < 0
826 || result == multmax && digit < -radix * multmax)) {
827 result = radix * result + digit;
828 }
829 if (inRange && i == endIndex && digit >= 0) {
830 return result;
831 }
832 }
833 if (digit < 0) {
834 throw NumberFormatException.forCharSequence(s, beginIndex,
835 endIndex, i - (digit < -1 ? 0 : 1));
836 }
837 throw new NumberFormatException(String.format(
838 "String value %s exceeds range of unsigned int.", s));
839 }
840
841 /**
842 * Parses the string argument as an unsigned decimal integer. The
843 * characters in the string must all be decimal digits, except
844 * that the first character may be an ASCII plus sign {@code
845 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
846 * is returned, exactly as if the argument and the radix 10 were
847 * given as arguments to the {@link
848 * #parseUnsignedInt(java.lang.String, int)} method.
849 *
850 * @param s a {@code String} containing the unsigned {@code int}
851 * representation to be parsed
852 * @return the unsigned integer value represented by the argument in decimal.
853 * @throws NumberFormatException if the string does not contain a
854 * parsable unsigned integer.
855 * @since 1.8
856 */
857 public static int parseUnsignedInt(String s) throws NumberFormatException {
858 return parseUnsignedInt(s, 10);
859 }
860
861 /**
862 * Returns an {@code Integer} object holding the value
863 * extracted from the specified {@code String} when parsed
864 * with the radix given by the second argument. The first argument
865 * is interpreted as representing a signed integer in the radix
866 * specified by the second argument, exactly as if the arguments
867 * were given to the {@link #parseInt(java.lang.String, int)}
868 * method. The result is an {@code Integer} object that
869 * represents the integer value specified by the string.
870 *
871 * <p>In other words, this method returns an {@code Integer}
872 * object equal to the value of:
873 *
874 * <blockquote>
875 * {@code Integer.valueOf(Integer.parseInt(s, radix))}
876 * </blockquote>
877 *
878 * @param s the string to be parsed.
879 * @param radix the radix to be used in interpreting {@code s}
880 * @return an {@code Integer} object holding the value
881 * represented by the string argument in the specified
882 * radix.
883 * @throws NumberFormatException if the {@code String}
884 * does not contain a parsable {@code int}.
885 */
886 public static Integer valueOf(String s, int radix) throws NumberFormatException {
887 return Integer.valueOf(parseInt(s,radix));
888 }
889
890 /**
891 * Returns an {@code Integer} object holding the
892 * value of the specified {@code String}. The argument is
893 * interpreted as representing a signed decimal integer, exactly
894 * as if the argument were given to the {@link
895 * #parseInt(java.lang.String)} method. The result is an
896 * {@code Integer} object that represents the integer value
897 * specified by the string.
898 *
899 * <p>In other words, this method returns an {@code Integer}
900 * object equal to the value of:
901 *
902 * <blockquote>
903 * {@code Integer.valueOf(Integer.parseInt(s))}
904 * </blockquote>
905 *
906 * @param s the string to be parsed.
907 * @return an {@code Integer} object holding the value
908 * represented by the string argument.
909 * @throws NumberFormatException if the string cannot be parsed
910 * as an integer.
911 */
912 public static Integer valueOf(String s) throws NumberFormatException {
913 return Integer.valueOf(parseInt(s, 10));
914 }
915
916 /**
917 * Cache to support the object identity semantics of autoboxing for values between
918 * -128 and 127 (inclusive) as required by JLS.
919 *
920 * The cache is initialized on first usage. The size of the cache
921 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
922 * During VM initialization, java.lang.Integer.IntegerCache.high property
923 * may be set and saved in the private system properties in the
924 * jdk.internal.misc.VM class.
925 *
926 * WARNING: The cache is archived with CDS and reloaded from the shared
927 * archive at runtime. The archived cache (Integer[]) and Integer objects
928 * reside in the closed archive heap regions. Care should be taken when
929 * changing the implementation and the cache array should not be assigned
930 * with new Integer object(s) after initialization.
931 */
932
933 private static final class IntegerCache {
934 static final int low = -128;
935 static final int high;
936
937 @Stable
938 static final Integer[] cache;
939 static Integer[] archivedCache;
940
941 static {
942 // high value may be configured by property
943 int h = 127;
944 String integerCacheHighPropValue =
945 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
946 if (integerCacheHighPropValue != null) {
947 try {
948 h = Math.max(parseInt(integerCacheHighPropValue), 127);
949 // Maximum array size is Integer.MAX_VALUE
950 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
951 } catch( NumberFormatException nfe) {
952 // If the property cannot be parsed into an int, ignore it.
953 }
954 }
955 high = h;
956
957 // Load IntegerCache.archivedCache from archive, if possible
958 CDS.initializeFromArchive(IntegerCache.class);
959 int size = (high - low) + 1;
960
961 // Use the archived cache if it exists and is large enough
962 if (archivedCache == null || size > archivedCache.length) {
963 Integer[] c = new Integer[size];
964 int j = low;
965 // If archive has Integer cache, we must use all instances from it.
966 // Otherwise, the identity checks between archived Integers and
967 // runtime-cached Integers would fail.
968 int archivedSize = (archivedCache == null) ? 0 : archivedCache.length;
969 for (int i = 0; i < archivedSize; i++) {
970 c[i] = archivedCache[i];
971 assert j == archivedCache[i];
972 j++;
973 }
974 // Fill the rest of the cache.
975 for (int i = archivedSize; i < size; i++) {
976 c[i] = new Integer(j++);
977 }
978 archivedCache = c;
979 }
980 cache = archivedCache;
981 // range [-128, 127] must be interned (JLS7 5.1.7)
982 assert IntegerCache.high >= 127;
983 }
984
985 private IntegerCache() {}
986 }
987
988 /**
989 * Returns an {@code Integer} instance representing the specified
990 * {@code int} value. If a new {@code Integer} instance is not
991 * required, this method should generally be used in preference to
992 * the constructor {@link #Integer(int)}, as this method is likely
993 * to yield significantly better space and time performance by
994 * caching frequently requested values.
995 *
996 * This method will always cache values in the range -128 to 127,
997 * inclusive, and may cache other values outside of this range.
998 *
999 * @param i an {@code int} value.
1000 * @return an {@code Integer} instance representing {@code i}.
1001 * @since 1.5
1002 */
1003 @IntrinsicCandidate
1004 @DeserializeConstructor
1005 public static Integer valueOf(int i) {
1006 if (i >= IntegerCache.low && i <= IntegerCache.high)
1007 return IntegerCache.cache[i + (-IntegerCache.low)];
1008 return new Integer(i);
1009 }
1010
1011 /**
1012 * The value of the {@code Integer}.
1013 *
1014 * @serial
1015 */
1016 private final int value;
1017
1018 /**
1019 * Constructs a newly allocated {@code Integer} object that
1020 * represents the specified {@code int} value.
1021 *
1022 * @param value the value to be represented by the
1023 * {@code Integer} object.
1024 *
1025 * @deprecated
1026 * It is rarely appropriate to use this constructor. The static factory
1027 * {@link #valueOf(int)} is generally a better choice, as it is
1028 * likely to yield significantly better space and time performance.
1029 */
1030 @Deprecated(since="9", forRemoval = true)
1031 public Integer(int value) {
1032 this.value = value;
1033 }
1034
1035 /**
1036 * Constructs a newly allocated {@code Integer} object that
1037 * represents the {@code int} value indicated by the
1038 * {@code String} parameter. The string is converted to an
1039 * {@code int} value in exactly the manner used by the
1040 * {@code parseInt} method for radix 10.
1041 *
1042 * @param s the {@code String} to be converted to an {@code Integer}.
1043 * @throws NumberFormatException if the {@code String} does not
1044 * contain a parsable integer.
1045 *
1046 * @deprecated
1047 * It is rarely appropriate to use this constructor.
1048 * Use {@link #parseInt(String)} to convert a string to a
1049 * {@code int} primitive, or use {@link #valueOf(String)}
1050 * to convert a string to an {@code Integer} object.
1051 */
1052 @Deprecated(since="9", forRemoval = true)
1053 public Integer(String s) throws NumberFormatException {
1054 this.value = parseInt(s, 10);
1055 }
1056
1057 /**
1058 * Returns the value of this {@code Integer} as a {@code byte}
1059 * after a narrowing primitive conversion.
1060 * @jls 5.1.3 Narrowing Primitive Conversion
1061 */
1062 public byte byteValue() {
1063 return (byte)value;
1064 }
1065
1066 /**
1067 * Returns the value of this {@code Integer} as a {@code short}
1068 * after a narrowing primitive conversion.
1069 * @jls 5.1.3 Narrowing Primitive Conversion
1070 */
1071 public short shortValue() {
1072 return (short)value;
1073 }
1074
1075 /**
1076 * Returns the value of this {@code Integer} as an
1077 * {@code int}.
1078 */
1079 @IntrinsicCandidate
1080 public int intValue() {
1081 return value;
1082 }
1083
1084 /**
1085 * Returns the value of this {@code Integer} as a {@code long}
1086 * after a widening primitive conversion.
1087 * @jls 5.1.2 Widening Primitive Conversion
1088 * @see Integer#toUnsignedLong(int)
1089 */
1090 public long longValue() {
1091 return (long)value;
1092 }
1093
1094 /**
1095 * Returns the value of this {@code Integer} as a {@code float}
1096 * after a widening primitive conversion.
1097 * @jls 5.1.2 Widening Primitive Conversion
1098 */
1099 public float floatValue() {
1100 return (float)value;
1101 }
1102
1103 /**
1104 * Returns the value of this {@code Integer} as a {@code double}
1105 * after a widening primitive conversion.
1106 * @jls 5.1.2 Widening Primitive Conversion
1107 */
1108 public double doubleValue() {
1109 return (double)value;
1110 }
1111
1112 /**
1113 * Returns a {@code String} object representing this
1114 * {@code Integer}'s value. The value is converted to signed
1115 * decimal representation and returned as a string, exactly as if
1116 * the integer value were given as an argument to the {@link
1117 * java.lang.Integer#toString(int)} method.
1118 *
1119 * @return a string representation of the value of this object in
1120 * base 10.
1121 */
1122 public String toString() {
1123 return toString(value);
1124 }
1125
1126 /**
1127 * Returns a hash code for this {@code Integer}.
1128 *
1129 * @return a hash code value for this object, equal to the
1130 * primitive {@code int} value represented by this
1131 * {@code Integer} object.
1132 */
1133 @Override
1134 public int hashCode() {
1135 return Integer.hashCode(value);
1136 }
1137
1138 /**
1139 * Returns a hash code for an {@code int} value; compatible with
1140 * {@code Integer.hashCode()}.
1141 *
1142 * @param value the value to hash
1143 * @since 1.8
1144 *
1145 * @return a hash code value for an {@code int} value.
1146 */
1147 public static int hashCode(int value) {
1148 return value;
1149 }
1150
1151 /**
1152 * Compares this object to the specified object. The result is
1153 * {@code true} if and only if the argument is not
1154 * {@code null} and is an {@code Integer} object that
1155 * contains the same {@code int} value as this object.
1156 *
1157 * @param obj the object to compare with.
1158 * @return {@code true} if the objects are the same;
1159 * {@code false} otherwise.
1160 */
1161 public boolean equals(Object obj) {
1162 if (obj instanceof Integer i) {
1163 return value == i.intValue();
1164 }
1165 return false;
1166 }
1167
1168 /**
1169 * Determines the integer value of the system property with the
1170 * specified name.
1171 *
1172 * <p>The first argument is treated as the name of a system
1173 * property. System properties are accessible through the {@link
1174 * java.lang.System#getProperty(java.lang.String)} method. The
1175 * string value of this property is then interpreted as an integer
1176 * value using the grammar supported by {@link Integer#decode decode} and
1177 * an {@code Integer} object representing this value is returned.
1178 *
1179 * <p>If there is no property with the specified name, if the
1180 * specified name is empty or {@code null}, or if the property
1181 * does not have the correct numeric format, then {@code null} is
1182 * returned.
1183 *
1184 * <p>In other words, this method returns an {@code Integer}
1185 * object equal to the value of:
1186 *
1187 * <blockquote>
1188 * {@code getInteger(nm, null)}
1189 * </blockquote>
1190 *
1191 * @param nm property name.
1192 * @return the {@code Integer} value of the property.
1193 * @throws SecurityException for the same reasons as
1194 * {@link System#getProperty(String) System.getProperty}
1195 * @see java.lang.System#getProperty(java.lang.String)
1196 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1197 */
1198 public static Integer getInteger(String nm) {
1199 return getInteger(nm, null);
1200 }
1201
1202 /**
1203 * Determines the integer value of the system property with the
1204 * specified name.
1205 *
1206 * <p>The first argument is treated as the name of a system
1207 * property. System properties are accessible through the {@link
1208 * java.lang.System#getProperty(java.lang.String)} method. The
1209 * string value of this property is then interpreted as an integer
1210 * value using the grammar supported by {@link Integer#decode decode} and
1211 * an {@code Integer} object representing this value is returned.
1212 *
1213 * <p>The second argument is the default value. An {@code Integer} object
1214 * that represents the value of the second argument is returned if there
1215 * is no property of the specified name, if the property does not have
1216 * the correct numeric format, or if the specified name is empty or
1217 * {@code null}.
1218 *
1219 * <p>In other words, this method returns an {@code Integer} object
1220 * equal to the value of:
1221 *
1222 * <blockquote>
1223 * {@code getInteger(nm, Integer.valueOf(val))}
1224 * </blockquote>
1225 *
1226 * but in practice it may be implemented in a manner such as:
1227 *
1228 * <blockquote><pre>
1229 * Integer result = getInteger(nm, null);
1230 * return (result == null) ? Integer.valueOf(val) : result;
1231 * </pre></blockquote>
1232 *
1233 * to avoid the unnecessary allocation of an {@code Integer}
1234 * object when the default value is not needed.
1235 *
1236 * @param nm property name.
1237 * @param val default value.
1238 * @return the {@code Integer} value of the property.
1239 * @throws SecurityException for the same reasons as
1240 * {@link System#getProperty(String) System.getProperty}
1241 * @see java.lang.System#getProperty(java.lang.String)
1242 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1243 */
1244 public static Integer getInteger(String nm, int val) {
1245 Integer result = getInteger(nm, null);
1246 return (result == null) ? Integer.valueOf(val) : result;
1247 }
1248
1249 /**
1250 * Returns the integer value of the system property with the
1251 * specified name. The first argument is treated as the name of a
1252 * system property. System properties are accessible through the
1253 * {@link java.lang.System#getProperty(java.lang.String)} method.
1254 * The string value of this property is then interpreted as an
1255 * integer value, as per the {@link Integer#decode decode} method,
1256 * and an {@code Integer} object representing this value is
1257 * returned; in summary:
1258 *
1259 * <ul><li>If the property value begins with the two ASCII characters
1260 * {@code 0x} or the ASCII character {@code #}, not
1261 * followed by a minus sign, then the rest of it is parsed as a
1262 * hexadecimal integer exactly as by the method
1263 * {@link #valueOf(java.lang.String, int)} with radix 16.
1264 * <li>If the property value begins with the ASCII character
1265 * {@code 0} followed by another character, it is parsed as an
1266 * octal integer exactly as by the method
1267 * {@link #valueOf(java.lang.String, int)} with radix 8.
1268 * <li>Otherwise, the property value is parsed as a decimal integer
1269 * exactly as by the method {@link #valueOf(java.lang.String, int)}
1270 * with radix 10.
1271 * </ul>
1272 *
1273 * <p>The second argument is the default value. The default value is
1274 * returned if there is no property of the specified name, if the
1275 * property does not have the correct numeric format, or if the
1276 * specified name is empty or {@code null}.
1277 *
1278 * @param nm property name.
1279 * @param val default value.
1280 * @return the {@code Integer} value of the property.
1281 * @throws SecurityException for the same reasons as
1282 * {@link System#getProperty(String) System.getProperty}
1283 * @see System#getProperty(java.lang.String)
1284 * @see System#getProperty(java.lang.String, java.lang.String)
1285 */
1286 public static Integer getInteger(String nm, Integer val) {
1287 String v = null;
1288 try {
1289 v = System.getProperty(nm);
1290 } catch (IllegalArgumentException | NullPointerException e) {
1291 }
1292 if (v != null) {
1293 try {
1294 return Integer.decode(v);
1295 } catch (NumberFormatException e) {
1296 }
1297 }
1298 return val;
1299 }
1300
1301 /**
1302 * Decodes a {@code String} into an {@code Integer}.
1303 * Accepts decimal, hexadecimal, and octal numbers given
1304 * by the following grammar:
1305 *
1306 * <blockquote>
1307 * <dl>
1308 * <dt><i>DecodableString:</i>
1309 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1310 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1311 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1312 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1313 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1314 *
1315 * <dt><i>Sign:</i>
1316 * <dd>{@code -}
1317 * <dd>{@code +}
1318 * </dl>
1319 * </blockquote>
1320 *
1321 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1322 * are as defined in section {@jls 3.10.1} of
1323 * <cite>The Java Language Specification</cite>,
1324 * except that underscores are not accepted between digits.
1325 *
1326 * <p>The sequence of characters following an optional
1327 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1328 * "{@code #}", or leading zero) is parsed as by the {@code
1329 * Integer.parseInt} method with the indicated radix (10, 16, or
1330 * 8). This sequence of characters must represent a positive
1331 * value or a {@link NumberFormatException} will be thrown. The
1332 * result is negated if first character of the specified {@code
1333 * String} is the minus sign. No whitespace characters are
1334 * permitted in the {@code String}.
1335 *
1336 * @param nm the {@code String} to decode.
1337 * @return an {@code Integer} object holding the {@code int}
1338 * value represented by {@code nm}
1339 * @throws NumberFormatException if the {@code String} does not
1340 * contain a parsable integer.
1341 * @see java.lang.Integer#parseInt(java.lang.String, int)
1342 */
1343 public static Integer decode(String nm) throws NumberFormatException {
1344 int radix = 10;
1345 int index = 0;
1346 boolean negative = false;
1347 int result;
1348
1349 if (nm.isEmpty())
1350 throw new NumberFormatException("Zero length string");
1351 char firstChar = nm.charAt(0);
1352 // Handle sign, if present
1353 if (firstChar == '-') {
1354 negative = true;
1355 index++;
1356 } else if (firstChar == '+')
1357 index++;
1358
1359 // Handle radix specifier, if present
1360 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1361 index += 2;
1362 radix = 16;
1363 }
1364 else if (nm.startsWith("#", index)) {
1365 index ++;
1366 radix = 16;
1367 }
1368 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1369 index ++;
1370 radix = 8;
1371 }
1372
1373 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1374 throw new NumberFormatException("Sign character in wrong position");
1375
1376 try {
1377 result = parseInt(nm, index, nm.length(), radix);
1378 result = negative ? -result : result;
1379 } catch (NumberFormatException e) {
1380 // If number is Integer.MIN_VALUE, we'll end up here. The next line
1381 // handles this case, and causes any genuine format error to be
1382 // rethrown.
1383 String constant = negative ? ("-" + nm.substring(index))
1384 : nm.substring(index);
1385 result = parseInt(constant, radix);
1386 }
1387 return result;
1388 }
1389
1390 /**
1391 * Compares two {@code Integer} objects numerically.
1392 *
1393 * @param anotherInteger the {@code Integer} to be compared.
1394 * @return the value {@code 0} if this {@code Integer} is
1395 * equal to the argument {@code Integer}; a value less than
1396 * {@code 0} if this {@code Integer} is numerically less
1397 * than the argument {@code Integer}; and a value greater
1398 * than {@code 0} if this {@code Integer} is numerically
1399 * greater than the argument {@code Integer} (signed
1400 * comparison).
1401 * @since 1.2
1402 */
1403 public int compareTo(Integer anotherInteger) {
1404 return compare(this.value, anotherInteger.value);
1405 }
1406
1407 /**
1408 * Compares two {@code int} values numerically.
1409 * The value returned is identical to what would be returned by:
1410 * <pre>
1411 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1412 * </pre>
1413 *
1414 * @param x the first {@code int} to compare
1415 * @param y the second {@code int} to compare
1416 * @return the value {@code 0} if {@code x == y};
1417 * a value less than {@code 0} if {@code x < y}; and
1418 * a value greater than {@code 0} if {@code x > y}
1419 * @since 1.7
1420 */
1421 public static int compare(int x, int y) {
1422 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1423 }
1424
1425 /**
1426 * Compares two {@code int} values numerically treating the values
1427 * as unsigned.
1428 *
1429 * @param x the first {@code int} to compare
1430 * @param y the second {@code int} to compare
1431 * @return the value {@code 0} if {@code x == y}; a value less
1432 * than {@code 0} if {@code x < y} as unsigned values; and
1433 * a value greater than {@code 0} if {@code x > y} as
1434 * unsigned values
1435 * @since 1.8
1436 */
1437 @IntrinsicCandidate
1438 public static int compareUnsigned(int x, int y) {
1439 return compare(x + MIN_VALUE, y + MIN_VALUE);
1440 }
1441
1442 /**
1443 * Converts the argument to a {@code long} by an unsigned
1444 * conversion. In an unsigned conversion to a {@code long}, the
1445 * high-order 32 bits of the {@code long} are zero and the
1446 * low-order 32 bits are equal to the bits of the integer
1447 * argument.
1448 *
1449 * Consequently, zero and positive {@code int} values are mapped
1450 * to a numerically equal {@code long} value and negative {@code
1451 * int} values are mapped to a {@code long} value equal to the
1452 * input plus 2<sup>32</sup>.
1453 *
1454 * @param x the value to convert to an unsigned {@code long}
1455 * @return the argument converted to {@code long} by an unsigned
1456 * conversion
1457 * @since 1.8
1458 */
1459 public static long toUnsignedLong(int x) {
1460 return ((long) x) & 0xffffffffL;
1461 }
1462
1463 /**
1464 * Returns the unsigned quotient of dividing the first argument by
1465 * the second where each argument and the result is interpreted as
1466 * an unsigned value.
1467 *
1468 * <p>Note that in two's complement arithmetic, the three other
1469 * basic arithmetic operations of add, subtract, and multiply are
1470 * bit-wise identical if the two operands are regarded as both
1471 * being signed or both being unsigned. Therefore separate {@code
1472 * addUnsigned}, etc. methods are not provided.
1473 *
1474 * @param dividend the value to be divided
1475 * @param divisor the value doing the dividing
1476 * @return the unsigned quotient of the first argument divided by
1477 * the second argument
1478 * @see #remainderUnsigned
1479 * @since 1.8
1480 */
1481 @IntrinsicCandidate
1482 public static int divideUnsigned(int dividend, int divisor) {
1483 // In lieu of tricky code, for now just use long arithmetic.
1484 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor));
1485 }
1486
1487 /**
1488 * Returns the unsigned remainder from dividing the first argument
1489 * by the second where each argument and the result is interpreted
1490 * as an unsigned value.
1491 *
1492 * @param dividend the value to be divided
1493 * @param divisor the value doing the dividing
1494 * @return the unsigned remainder of the first argument divided by
1495 * the second argument
1496 * @see #divideUnsigned
1497 * @since 1.8
1498 */
1499 @IntrinsicCandidate
1500 public static int remainderUnsigned(int dividend, int divisor) {
1501 // In lieu of tricky code, for now just use long arithmetic.
1502 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor));
1503 }
1504
1505
1506 // Bit twiddling
1507
1508 /**
1509 * The number of bits used to represent an {@code int} value in two's
1510 * complement binary form.
1511 *
1512 * @since 1.5
1513 */
1514 @Native public static final int SIZE = 32;
1515
1516 /**
1517 * The number of bytes used to represent an {@code int} value in two's
1518 * complement binary form.
1519 *
1520 * @since 1.8
1521 */
1522 public static final int BYTES = SIZE / Byte.SIZE;
1523
1524 /**
1525 * Returns an {@code int} value with at most a single one-bit, in the
1526 * position of the highest-order ("leftmost") one-bit in the specified
1527 * {@code int} value. Returns zero if the specified value has no
1528 * one-bits in its two's complement binary representation, that is, if it
1529 * is equal to zero.
1530 *
1531 * @param i the value whose highest one bit is to be computed
1532 * @return an {@code int} value with a single one-bit, in the position
1533 * of the highest-order one-bit in the specified value, or zero if
1534 * the specified value is itself equal to zero.
1535 * @since 1.5
1536 */
1537 public static int highestOneBit(int i) {
1538 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1539 }
1540
1541 /**
1542 * Returns an {@code int} value with at most a single one-bit, in the
1543 * position of the lowest-order ("rightmost") one-bit in the specified
1544 * {@code int} value. Returns zero if the specified value has no
1545 * one-bits in its two's complement binary representation, that is, if it
1546 * is equal to zero.
1547 *
1548 * @param i the value whose lowest one bit is to be computed
1549 * @return an {@code int} value with a single one-bit, in the position
1550 * of the lowest-order one-bit in the specified value, or zero if
1551 * the specified value is itself equal to zero.
1552 * @since 1.5
1553 */
1554 public static int lowestOneBit(int i) {
1555 // HD, Section 2-1
1556 return i & -i;
1557 }
1558
1559 /**
1560 * Returns the number of zero bits preceding the highest-order
1561 * ("leftmost") one-bit in the two's complement binary representation
1562 * of the specified {@code int} value. Returns 32 if the
1563 * specified value has no one-bits in its two's complement representation,
1564 * in other words if it is equal to zero.
1565 *
1566 * <p>Note that this method is closely related to the logarithm base 2.
1567 * For all positive {@code int} values x:
1568 * <ul>
1569 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1570 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1571 * </ul>
1572 *
1573 * @param i the value whose number of leading zeros is to be computed
1574 * @return 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, or 32 if the value
1577 * is equal to zero.
1578 * @since 1.5
1579 */
1580 @IntrinsicCandidate
1581 public static int numberOfLeadingZeros(int i) {
1582 // HD, Count leading 0's
1583 if (i <= 0)
1584 return i == 0 ? 32 : 0;
1585 int n = 31;
1586 if (i >= 1 << 16) { n -= 16; i >>>= 16; }
1587 if (i >= 1 << 8) { n -= 8; i >>>= 8; }
1588 if (i >= 1 << 4) { n -= 4; i >>>= 4; }
1589 if (i >= 1 << 2) { n -= 2; i >>>= 2; }
1590 return n - (i >>> 1);
1591 }
1592
1593 /**
1594 * Returns the number of zero bits following the lowest-order ("rightmost")
1595 * one-bit in the two's complement binary representation of the specified
1596 * {@code int} value. Returns 32 if the specified value has no
1597 * one-bits in its two's complement representation, in other words if it is
1598 * equal to zero.
1599 *
1600 * @param i the value whose number of trailing zeros is to be computed
1601 * @return the number of zero bits following the lowest-order ("rightmost")
1602 * one-bit in the two's complement binary representation of the
1603 * specified {@code int} value, or 32 if the value is equal
1604 * to zero.
1605 * @since 1.5
1606 */
1607 @IntrinsicCandidate
1608 public static int numberOfTrailingZeros(int i) {
1609 // HD, Count trailing 0's
1610 i = ~i & (i - 1);
1611 if (i <= 0) return i & 32;
1612 int n = 1;
1613 if (i > 1 << 16) { n += 16; i >>>= 16; }
1614 if (i > 1 << 8) { n += 8; i >>>= 8; }
1615 if (i > 1 << 4) { n += 4; i >>>= 4; }
1616 if (i > 1 << 2) { n += 2; i >>>= 2; }
1617 return n + (i >>> 1);
1618 }
1619
1620 /**
1621 * Returns the number of one-bits in the two's complement binary
1622 * representation of the specified {@code int} value. This function is
1623 * sometimes referred to as the <i>population count</i>.
1624 *
1625 * @param i the value whose bits are to be counted
1626 * @return the number of one-bits in the two's complement binary
1627 * representation of the specified {@code int} value.
1628 * @since 1.5
1629 */
1630 @IntrinsicCandidate
1631 public static int bitCount(int i) {
1632 // HD, Figure 5-2
1633 i = i - ((i >>> 1) & 0x55555555);
1634 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1635 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1636 i = i + (i >>> 8);
1637 i = i + (i >>> 16);
1638 return i & 0x3f;
1639 }
1640
1641 /**
1642 * Returns the value obtained by rotating the two's complement binary
1643 * representation of the specified {@code int} value left by the
1644 * specified number of bits. (Bits shifted out of the left hand, or
1645 * high-order, side reenter on the right, or low-order.)
1646 *
1647 * <p>Note that left rotation with a negative distance is equivalent to
1648 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1649 * distance)}. Note also that rotation by any multiple of 32 is a
1650 * no-op, so all but the last five bits of the rotation distance can be
1651 * ignored, even if the distance is negative: {@code rotateLeft(val,
1652 * distance) == rotateLeft(val, distance & 0x1F)}.
1653 *
1654 * @param i the value whose bits are to be rotated left
1655 * @param distance the number of bit positions to rotate left
1656 * @return 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.
1659 * @since 1.5
1660 */
1661 public static int rotateLeft(int i, int distance) {
1662 return (i << distance) | (i >>> -distance);
1663 }
1664
1665 /**
1666 * Returns the value obtained by rotating the two's complement binary
1667 * representation of the specified {@code int} value right by the
1668 * specified number of bits. (Bits shifted out of the right hand, or
1669 * low-order, side reenter on the left, or high-order.)
1670 *
1671 * <p>Note that right rotation with a negative distance is equivalent to
1672 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1673 * distance)}. Note also that rotation by any multiple of 32 is a
1674 * no-op, so all but the last five bits of the rotation distance can be
1675 * ignored, even if the distance is negative: {@code rotateRight(val,
1676 * distance) == rotateRight(val, distance & 0x1F)}.
1677 *
1678 * @param i the value whose bits are to be rotated right
1679 * @param distance the number of bit positions to rotate right
1680 * @return 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.
1683 * @since 1.5
1684 */
1685 public static int rotateRight(int i, int distance) {
1686 return (i >>> distance) | (i << -distance);
1687 }
1688
1689 /**
1690 * Returns the value obtained by reversing the order of the bits in the
1691 * two's complement binary representation of the specified {@code int}
1692 * value.
1693 *
1694 * @param i the value to be reversed
1695 * @return the value obtained by reversing order of the bits in the
1696 * specified {@code int} value.
1697 * @since 1.5
1698 */
1699 @IntrinsicCandidate
1700 public static int reverse(int i) {
1701 // HD, Figure 7-1
1702 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1703 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1704 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1705
1706 return reverseBytes(i);
1707 }
1708
1709 /**
1710 * Returns the value obtained by compressing the bits of the
1711 * specified {@code int} value, {@code i}, in accordance with
1712 * the specified bit mask.
1713 * <p>
1714 * For each one-bit value {@code mb} of the mask, from least
1715 * significant to most significant, the bit value of {@code i} at
1716 * the same bit location as {@code mb} is assigned to the compressed
1717 * value contiguously starting from the least significant bit location.
1718 * All the upper remaining bits of the compressed value are set
1719 * to zero.
1720 *
1721 * @apiNote
1722 * Consider the simple case of compressing the digits of a hexadecimal
1723 * value:
1724 * {@snippet lang="java" :
1725 * // Compressing drink to food
1726 * compress(0xCAFEBABE, 0xFF00FFF0) == 0xCABAB
1727 * }
1728 * Starting from the least significant hexadecimal digit at position 0
1729 * from the right, the mask {@code 0xFF00FFF0} selects hexadecimal digits
1730 * at positions 1, 2, 3, 6 and 7 of {@code 0xCAFEBABE}. The selected digits
1731 * occur in the resulting compressed value contiguously from digit position
1732 * 0 in the same order.
1733 * <p>
1734 * The following identities all return {@code true} and are helpful to
1735 * understand the behaviour of {@code compress}:
1736 * {@snippet lang="java" :
1737 * // Returns 1 if the bit at position n is one
1738 * compress(x, 1 << n) == (x >> n & 1)
1739 *
1740 * // Logical shift right
1741 * compress(x, -1 << n) == x >>> n
1742 *
1743 * // Any bits not covered by the mask are ignored
1744 * compress(x, m) == compress(x & m, m)
1745 *
1746 * // Compressing a value by itself
1747 * compress(m, m) == (m == -1 || m == 0) ? m : (1 << bitCount(m)) - 1
1748 *
1749 * // Expanding then compressing with the same mask
1750 * compress(expand(x, m), m) == x & compress(m, m)
1751 * }
1752 * <p>
1753 * The Sheep And Goats (SAG) operation (see Hacker's Delight, Second Edition, section 7.7)
1754 * can be implemented as follows:
1755 * {@snippet lang="java" :
1756 * int compressLeft(int i, int mask) {
1757 * // This implementation follows the description in Hacker's Delight which
1758 * // is informative. A more optimal implementation is:
1759 * // Integer.compress(i, mask) << -Integer.bitCount(mask)
1760 * return Integer.reverse(
1761 * Integer.compress(Integer.reverse(i), Integer.reverse(mask)));
1762 * }
1763 *
1764 * int sag(int i, int mask) {
1765 * return compressLeft(i, mask) | Integer.compress(i, ~mask);
1766 * }
1767 *
1768 * // Separate the sheep from the goats
1769 * sag(0xCAFEBABE, 0xFF00FFF0) == 0xCABABFEE
1770 * }
1771 *
1772 * @param i the value whose bits are to be compressed
1773 * @param mask the bit mask
1774 * @return the compressed value
1775 * @see #expand
1776 * @since 19
1777 */
1778 @IntrinsicCandidate
1779 public static int compress(int i, int mask) {
1780 // See Hacker's Delight (2nd ed) section 7.4 Compress, or Generalized Extract
1781
1782 i = i & mask; // Clear irrelevant bits
1783 int maskCount = ~mask << 1; // Count 0's to right
1784
1785 for (int j = 0; j < 5; j++) {
1786 // Parallel prefix
1787 // Mask prefix identifies bits of the mask that have an odd number of 0's to the right
1788 int maskPrefix = parallelSuffix(maskCount);
1789 // Bits to move
1790 int maskMove = maskPrefix & mask;
1791 // Compress mask
1792 mask = (mask ^ maskMove) | (maskMove >>> (1 << j));
1793 // Bits of i to be moved
1794 int t = i & maskMove;
1795 // Compress i
1796 i = (i ^ t) | (t >>> (1 << j));
1797 // Adjust the mask count by identifying bits that have 0 to the right
1798 maskCount = maskCount & ~maskPrefix;
1799 }
1800 return i;
1801 }
1802
1803 /**
1804 * Returns the value obtained by expanding the bits of the
1805 * specified {@code int} value, {@code i}, in accordance with
1806 * the specified bit mask.
1807 * <p>
1808 * For each one-bit value {@code mb} of the mask, from least
1809 * significant to most significant, the next contiguous bit value
1810 * of {@code i} starting at the least significant bit is assigned
1811 * to the expanded value at the same bit location as {@code mb}.
1812 * All other remaining bits of the expanded value are set to zero.
1813 *
1814 * @apiNote
1815 * Consider the simple case of expanding the digits of a hexadecimal
1816 * value:
1817 * {@snippet lang="java" :
1818 * expand(0x0000CABAB, 0xFF00FFF0) == 0xCA00BAB0
1819 * }
1820 * Starting from the least significant hexadecimal digit at position 0
1821 * from the right, the mask {@code 0xFF00FFF0} selects the first five
1822 * hexadecimal digits of {@code 0x0000CABAB}. The selected digits occur
1823 * in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.
1824 * <p>
1825 * The following identities all return {@code true} and are helpful to
1826 * understand the behaviour of {@code expand}:
1827 * {@snippet lang="java" :
1828 * // Logically shift right the bit at position 0
1829 * expand(x, 1 << n) == (x & 1) << n
1830 *
1831 * // Logically shift right
1832 * expand(x, -1 << n) == x << n
1833 *
1834 * // Expanding all bits returns the mask
1835 * expand(-1, m) == m
1836 *
1837 * // Any bits not covered by the mask are ignored
1838 * expand(x, m) == expand(x, m) & m
1839 *
1840 * // Compressing then expanding with the same mask
1841 * expand(compress(x, m), m) == x & m
1842 * }
1843 * <p>
1844 * The select operation for determining the position of the one-bit with
1845 * index {@code n} in a {@code int} value can be implemented as follows:
1846 * {@snippet lang="java" :
1847 * int select(int i, int n) {
1848 * // the one-bit in i (the mask) with index n
1849 * int nthBit = Integer.expand(1 << n, i);
1850 * // the bit position of the one-bit with index n
1851 * return Integer.numberOfTrailingZeros(nthBit);
1852 * }
1853 *
1854 * // The one-bit with index 0 is at bit position 1
1855 * select(0b10101010_10101010, 0) == 1
1856 * // The one-bit with index 3 is at bit position 7
1857 * select(0b10101010_10101010, 3) == 7
1858 * }
1859 *
1860 * @param i the value whose bits are to be expanded
1861 * @param mask the bit mask
1862 * @return the expanded value
1863 * @see #compress
1864 * @since 19
1865 */
1866 @IntrinsicCandidate
1867 public static int expand(int i, int mask) {
1868 // Save original mask
1869 int originalMask = mask;
1870 // Count 0's to right
1871 int maskCount = ~mask << 1;
1872 int maskPrefix = parallelSuffix(maskCount);
1873 // Bits to move
1874 int maskMove1 = maskPrefix & mask;
1875 // Compress mask
1876 mask = (mask ^ maskMove1) | (maskMove1 >>> (1 << 0));
1877 maskCount = maskCount & ~maskPrefix;
1878
1879 maskPrefix = parallelSuffix(maskCount);
1880 // Bits to move
1881 int maskMove2 = maskPrefix & mask;
1882 // Compress mask
1883 mask = (mask ^ maskMove2) | (maskMove2 >>> (1 << 1));
1884 maskCount = maskCount & ~maskPrefix;
1885
1886 maskPrefix = parallelSuffix(maskCount);
1887 // Bits to move
1888 int maskMove3 = maskPrefix & mask;
1889 // Compress mask
1890 mask = (mask ^ maskMove3) | (maskMove3 >>> (1 << 2));
1891 maskCount = maskCount & ~maskPrefix;
1892
1893 maskPrefix = parallelSuffix(maskCount);
1894 // Bits to move
1895 int maskMove4 = maskPrefix & mask;
1896 // Compress mask
1897 mask = (mask ^ maskMove4) | (maskMove4 >>> (1 << 3));
1898 maskCount = maskCount & ~maskPrefix;
1899
1900 maskPrefix = parallelSuffix(maskCount);
1901 // Bits to move
1902 int maskMove5 = maskPrefix & mask;
1903
1904 int t = i << (1 << 4);
1905 i = (i & ~maskMove5) | (t & maskMove5);
1906 t = i << (1 << 3);
1907 i = (i & ~maskMove4) | (t & maskMove4);
1908 t = i << (1 << 2);
1909 i = (i & ~maskMove3) | (t & maskMove3);
1910 t = i << (1 << 1);
1911 i = (i & ~maskMove2) | (t & maskMove2);
1912 t = i << (1 << 0);
1913 i = (i & ~maskMove1) | (t & maskMove1);
1914
1915 // Clear irrelevant bits
1916 return i & originalMask;
1917 }
1918
1919 @ForceInline
1920 private static int parallelSuffix(int maskCount) {
1921 int maskPrefix = maskCount ^ (maskCount << 1);
1922 maskPrefix = maskPrefix ^ (maskPrefix << 2);
1923 maskPrefix = maskPrefix ^ (maskPrefix << 4);
1924 maskPrefix = maskPrefix ^ (maskPrefix << 8);
1925 maskPrefix = maskPrefix ^ (maskPrefix << 16);
1926 return maskPrefix;
1927 }
1928
1929 /**
1930 * Returns the signum function of the specified {@code int} value. (The
1931 * return value is -1 if the specified value is negative; 0 if the
1932 * specified value is zero; and 1 if the specified value is positive.)
1933 *
1934 * @param i the value whose signum is to be computed
1935 * @return the signum function of the specified {@code int} value.
1936 * @since 1.5
1937 */
1938 public static int signum(int i) {
1939 // HD, Section 2-7
1940 return (i >> 31) | (-i >>> 31);
1941 }
1942
1943 /**
1944 * Returns the value obtained by reversing the order of the bytes in the
1945 * two's complement representation of the specified {@code int} value.
1946 *
1947 * @param i the value whose bytes are to be reversed
1948 * @return the value obtained by reversing the bytes in the specified
1949 * {@code int} value.
1950 * @since 1.5
1951 */
1952 @IntrinsicCandidate
1953 public static int reverseBytes(int i) {
1954 return (i << 24) |
1955 ((i & 0xff00) << 8) |
1956 ((i >>> 8) & 0xff00) |
1957 (i >>> 24);
1958 }
1959
1960 /**
1961 * Adds two integers together as per the + operator.
1962 *
1963 * @param a the first operand
1964 * @param b the second operand
1965 * @return the sum of {@code a} and {@code b}
1966 * @see java.util.function.BinaryOperator
1967 * @since 1.8
1968 */
1969 public static int sum(int a, int b) {
1970 return a + b;
1971 }
1972
1973 /**
1974 * Returns the greater of two {@code int} values
1975 * as if by calling {@link Math#max(int, int) Math.max}.
1976 *
1977 * @param a the first operand
1978 * @param b the second operand
1979 * @return the greater of {@code a} and {@code b}
1980 * @see java.util.function.BinaryOperator
1981 * @since 1.8
1982 */
1983 public static int max(int a, int b) {
1984 return Math.max(a, b);
1985 }
1986
1987 /**
1988 * Returns the smaller of two {@code int} values
1989 * as if by calling {@link Math#min(int, int) Math.min}.
1990 *
1991 * @param a the first operand
1992 * @param b the second operand
1993 * @return the smaller of {@code a} and {@code b}
1994 * @see java.util.function.BinaryOperator
1995 * @since 1.8
1996 */
1997 public static int min(int a, int b) {
1998 return Math.min(a, b);
1999 }
2000
2001 /**
2002 * Returns an {@link Optional} containing the nominal descriptor for this
2003 * instance, which is the instance itself.
2004 *
2005 * @return an {@link Optional} describing the {@linkplain Integer} instance
2006 * @since 12
2007 */
2008 @Override
2009 public Optional<Integer> describeConstable() {
2010 return Optional.of(this);
2011 }
2012
2013 /**
2014 * Resolves this instance as a {@link ConstantDesc}, the result of which is
2015 * the instance itself.
2016 *
2017 * @param lookup ignored
2018 * @return the {@linkplain Integer} instance
2019 * @since 12
2020 */
2021 @Override
2022 public Integer resolveConstantDesc(MethodHandles.Lookup lookup) {
2023 return this;
2024 }
2025
2026 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2027 @java.io.Serial
2028 @Native private static final long serialVersionUID = 1360826667806852920L;
2029 }