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 {@linkplain #equals(Object) equal}
61 * as interchangeable and should not use instances for synchronization, mutexes, or
62 * with {@linkplain java.lang.ref.Reference object references}.
63 *
64 * <div class="preview-block">
65 * <div class="preview-comment">
66 * When preview features are enabled, {@code Integer} is a {@linkplain Class#isValue value class}.
67 * Use of value class instances for synchronization, mutexes, or with
68 * {@linkplain java.lang.ref.Reference object references} result in
69 * {@link IdentityException}.
70 * </div>
71 * </div>
72 *
73 * <p>Implementation note: The implementations of the "bit twiddling"
74 * methods (such as {@link #highestOneBit(int) highestOneBit} and
75 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
76 * based on material from Henry S. Warren, Jr.'s <cite>Hacker's
77 * Delight</cite>, (Addison Wesley, 2002) and <cite>Hacker's
78 * Delight, Second Edition</cite>, (Pearson Education, 2013).
79 *
80 * @author Lee Boynton
81 * @author Arthur van Hoff
82 * @author Josh Bloch
83 * @author Joseph D. Darcy
84 * @since 1.0
85 */
86 @jdk.internal.MigratedValueClass
87 @jdk.internal.ValueBased
88 public final class Integer extends Number
89 implements Comparable<Integer>, Constable, ConstantDesc {
90 /**
91 * A constant holding the minimum value an {@code int} can
92 * have, -2<sup>31</sup>.
93 */
94 @Native public static final int MIN_VALUE = 0x80000000;
95
96 /**
97 * A constant holding the maximum value an {@code int} can
98 * have, 2<sup>31</sup>-1.
99 */
100 @Native public static final int MAX_VALUE = 0x7fffffff;
101
102 /**
103 * The {@code Class} instance representing the primitive type
104 * {@code int}.
105 *
106 * @since 1.1
107 */
108 public static final Class<Integer> TYPE = Class.getPrimitiveClass("int");
109
110 /**
111 * All possible chars for representing a number as a String
112 */
113 static final char[] digits = {
114 '0' , '1' , '2' , '3' , '4' , '5' ,
115 '6' , '7' , '8' , '9' , 'a' , 'b' ,
116 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
117 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
118 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
119 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
120 };
121
122 /**
123 * Returns a string representation of the first argument in the
124 * radix specified by the second argument.
125 *
126 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
127 * or larger than {@code Character.MAX_RADIX}, then the radix
128 * {@code 10} is used instead.
129 *
130 * <p>If the first argument is negative, the first element of the
131 * result is the ASCII minus character {@code '-'}
132 * ({@code '\u005Cu002D'}). If the first argument is not
133 * negative, no sign character appears in the result.
134 *
135 * <p>The remaining characters of the result represent the magnitude
136 * of the first argument. If the magnitude is zero, it is
137 * represented by a single zero character {@code '0'}
138 * ({@code '\u005Cu0030'}); otherwise, the first character of
139 * the representation of the magnitude will not be the zero
140 * character. The following ASCII characters are used as digits:
141 *
142 * <blockquote>
143 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
144 * </blockquote>
145 *
146 * These are {@code '\u005Cu0030'} through
147 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
148 * {@code '\u005Cu007A'}. If {@code radix} is
149 * <var>N</var>, then the first <var>N</var> of these characters
150 * are used as radix-<var>N</var> digits in the order shown. Thus,
151 * the digits for hexadecimal (radix 16) are
152 * {@code 0123456789abcdef}. If uppercase letters are
153 * desired, the {@link java.lang.String#toUpperCase()} method may
154 * be called on the result:
155 *
156 * <blockquote>
157 * {@code Integer.toString(n, 16).toUpperCase()}
158 * </blockquote>
159 *
160 * @param i an integer to be converted to a string.
161 * @param radix the radix to use in the string representation.
162 * @return a string representation of the argument in the specified radix.
163 * @see java.lang.Character#MAX_RADIX
164 * @see java.lang.Character#MIN_RADIX
165 */
166 public static String toString(int i, int radix) {
167 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
168 radix = 10;
169
170 /* Use the faster version */
171 if (radix == 10) {
172 return toString(i);
173 }
174
175 if (COMPACT_STRINGS) {
176 byte[] buf = new byte[33];
177 boolean negative = (i < 0);
178 int charPos = 32;
179
180 if (!negative) {
181 i = -i;
182 }
183
184 while (i <= -radix) {
185 buf[charPos--] = (byte)digits[-(i % radix)];
186 i = i / radix;
187 }
188 buf[charPos] = (byte)digits[-i];
189
190 if (negative) {
191 buf[--charPos] = '-';
192 }
193
194 return StringLatin1.newString(buf, charPos, (33 - charPos));
195 }
196 return toStringUTF16(i, radix);
197 }
198
199 private static String toStringUTF16(int i, int radix) {
200 byte[] buf = new byte[33 * 2];
201 boolean negative = (i < 0);
202 int charPos = 32;
203 if (!negative) {
204 i = -i;
205 }
206 while (i <= -radix) {
207 StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
208 i = i / radix;
209 }
210 StringUTF16.putChar(buf, charPos, digits[-i]);
211
212 if (negative) {
213 StringUTF16.putChar(buf, --charPos, '-');
214 }
215 return StringUTF16.newString(buf, charPos, (33 - charPos));
216 }
217
218 /**
219 * Returns a string representation of the first argument as an
220 * unsigned integer value in the radix specified by the second
221 * argument.
222 *
223 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
224 * or larger than {@code Character.MAX_RADIX}, then the radix
225 * {@code 10} is used instead.
226 *
227 * <p>Note that since the first argument is treated as an unsigned
228 * value, no leading sign character is printed.
229 *
230 * <p>If the magnitude is zero, it is represented by a single zero
231 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
232 * the first character of the representation of the magnitude will
233 * not be the zero character.
234 *
235 * <p>The behavior of radixes and the characters used as digits
236 * are the same as {@link #toString(int, int) toString}.
237 *
238 * @param i an integer to be converted to an unsigned string.
239 * @param radix the radix to use in the string representation.
240 * @return an unsigned string representation of the argument in the specified radix.
241 * @see #toString(int, int)
242 * @since 1.8
243 */
244 public static String toUnsignedString(int i, int radix) {
245 return Long.toUnsignedString(toUnsignedLong(i), radix);
246 }
247
248 /**
249 * Returns a string representation of the integer argument as an
250 * unsigned integer in base 16.
251 *
252 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
253 * if the argument is negative; otherwise, it is equal to the
254 * argument. This value is converted to a string of ASCII digits
255 * in hexadecimal (base 16) with no extra leading
256 * {@code 0}s.
257 *
258 * <p>The value of the argument can be recovered from the returned
259 * string {@code s} by calling {@link
260 * Integer#parseUnsignedInt(String, int)
261 * Integer.parseUnsignedInt(s, 16)}.
262 *
263 * <p>If the unsigned magnitude is zero, it is represented by a
264 * single zero character {@code '0'} ({@code '\u005Cu0030'});
265 * otherwise, the first character of the representation of the
266 * unsigned magnitude will not be the zero character. The
267 * following characters are used as hexadecimal digits:
268 *
269 * <blockquote>
270 * {@code 0123456789abcdef}
271 * </blockquote>
272 *
273 * These are the characters {@code '\u005Cu0030'} through
274 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
275 * {@code '\u005Cu0066'}. If uppercase letters are
276 * desired, the {@link java.lang.String#toUpperCase()} method may
277 * be called on the result:
278 *
279 * <blockquote>
280 * {@code Integer.toHexString(n).toUpperCase()}
281 * </blockquote>
282 *
283 * @apiNote
284 * The {@link java.util.HexFormat} class provides formatting and parsing
285 * of byte arrays and primitives to return a string or adding to an {@link Appendable}.
286 * {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
287 * with leading zeros and for byte arrays includes for each byte
288 * a delimiter, prefix, and suffix.
289 *
290 * @param i an integer to be converted to a string.
291 * @return the string representation of the unsigned integer value
292 * represented by the argument in hexadecimal (base 16).
293 * @see java.util.HexFormat
294 * @see #parseUnsignedInt(String, int)
295 * @see #toUnsignedString(int, int)
296 * @since 1.0.2
297 */
298 public static String toHexString(int i) {
299 return toUnsignedString0(i, 4);
300 }
301
302 /**
303 * Returns a string representation of the integer argument as an
304 * unsigned integer in base 8.
305 *
306 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
307 * if the argument is negative; otherwise, it is equal to the
308 * argument. This value is converted to a string of ASCII digits
309 * in octal (base 8) with no extra leading {@code 0}s.
310 *
311 * <p>The value of the argument can be recovered from the returned
312 * string {@code s} by calling {@link
313 * Integer#parseUnsignedInt(String, int)
314 * Integer.parseUnsignedInt(s, 8)}.
315 *
316 * <p>If the unsigned magnitude is zero, it is represented by a
317 * single zero character {@code '0'} ({@code '\u005Cu0030'});
318 * otherwise, the first character of the representation of the
319 * unsigned magnitude will not be the zero character. The
320 * following characters are used as octal digits:
321 *
322 * <blockquote>
323 * {@code 01234567}
324 * </blockquote>
325 *
326 * These are the characters {@code '\u005Cu0030'} through
327 * {@code '\u005Cu0037'}.
328 *
329 * @param i an integer to be converted to a string.
330 * @return the string representation of the unsigned integer value
331 * represented by the argument in octal (base 8).
332 * @see #parseUnsignedInt(String, int)
333 * @see #toUnsignedString(int, int)
334 * @since 1.0.2
335 */
336 public static String toOctalString(int i) {
337 return toUnsignedString0(i, 3);
338 }
339
340 /**
341 * Returns a string representation of the integer argument as an
342 * unsigned integer in base 2.
343 *
344 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
345 * if the argument is negative; otherwise it is equal to the
346 * argument. This value is converted to a string of ASCII digits
347 * in binary (base 2) with no extra leading {@code 0}s.
348 *
349 * <p>The value of the argument can be recovered from the returned
350 * string {@code s} by calling {@link
351 * Integer#parseUnsignedInt(String, int)
352 * Integer.parseUnsignedInt(s, 2)}.
353 *
354 * <p>If the unsigned magnitude is zero, it is represented by a
355 * single zero character {@code '0'} ({@code '\u005Cu0030'});
356 * otherwise, the first character of the representation of the
357 * unsigned magnitude will not be the zero character. The
358 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
359 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
360 *
361 * @param i an integer to be converted to a string.
362 * @return the string representation of the unsigned integer value
363 * represented by the argument in binary (base 2).
364 * @see #parseUnsignedInt(String, int)
365 * @see #toUnsignedString(int, int)
366 * @since 1.0.2
367 */
368 public static String toBinaryString(int i) {
369 return toUnsignedString0(i, 1);
370 }
371
372 /**
373 * Convert the integer to an unsigned number.
374 */
375 private static String toUnsignedString0(int val, int shift) {
376 // assert shift > 0 && shift <=5 : "Illegal shift value";
377 int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
378 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
379 if (COMPACT_STRINGS) {
380 byte[] buf = new byte[chars];
381 formatUnsignedInt(val, shift, buf, chars);
382 return new String(buf, LATIN1);
383 } else {
384 byte[] buf = new byte[chars * 2];
385 formatUnsignedIntUTF16(val, shift, buf, chars);
386 return new String(buf, UTF16);
387 }
388 }
389
390 /**
391 * Format an {@code int} (treated as unsigned) into a byte buffer (LATIN1 version). If
392 * {@code len} exceeds the formatted ASCII representation of {@code val},
393 * {@code buf} will be padded with leading zeroes.
394 *
395 * @param val the unsigned int to format
396 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
397 * @param buf the byte buffer to write to
398 * @param len the number of characters to write
399 */
400 private static void formatUnsignedInt(int val, int shift, byte[] buf, int len) {
401 int charPos = len;
402 int radix = 1 << shift;
403 int mask = radix - 1;
404 do {
405 buf[--charPos] = (byte)Integer.digits[val & mask];
406 val >>>= shift;
407 } while (charPos > 0);
408 }
409
410 /**
411 * Format an {@code int} (treated as unsigned) into a byte buffer (UTF16 version). If
412 * {@code len} exceeds the formatted ASCII representation of {@code val},
413 * {@code buf} will be padded with leading zeroes.
414 *
415 * @param val the unsigned int to format
416 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
417 * @param buf the byte buffer to write to
418 * @param len the number of characters to write
419 */
420 private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int len) {
421 int charPos = len;
422 int radix = 1 << shift;
423 int mask = radix - 1;
424 do {
425 StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
426 val >>>= shift;
427 } while (charPos > 0);
428 }
429
430 /**
431 * Returns a {@code String} object representing the
432 * specified integer. The argument is converted to signed decimal
433 * representation and returned as a string, exactly as if the
434 * argument and radix 10 were given as arguments to the {@link
435 * #toString(int, int)} method.
436 *
437 * @param i an integer to be converted.
438 * @return a string representation of the argument in base 10.
439 */
440 @IntrinsicCandidate
441 public static String toString(int i) {
442 int size = DecimalDigits.stringSize(i);
443 if (COMPACT_STRINGS) {
444 byte[] buf = new byte[size];
445 StringLatin1.getChars(i, size, buf);
446 return new String(buf, LATIN1);
447 } else {
448 byte[] buf = new byte[size * 2];
449 StringUTF16.getChars(i, size, buf);
450 return new String(buf, UTF16);
451 }
452 }
453
454 /**
455 * Returns a string representation of the argument as an unsigned
456 * decimal value.
457 *
458 * The argument is converted to unsigned decimal representation
459 * and returned as a string exactly as if the argument and radix
460 * 10 were given as arguments to the {@link #toUnsignedString(int,
461 * int)} method.
462 *
463 * @param i an integer to be converted to an unsigned string.
464 * @return an unsigned string representation of the argument.
465 * @see #toUnsignedString(int, int)
466 * @since 1.8
467 */
468 public static String toUnsignedString(int i) {
469 return Long.toString(toUnsignedLong(i));
470 }
471
472 /**
473 * Parses the string argument as a signed integer in the radix
474 * specified by the second argument. The characters in the string
475 * must all be digits of the specified radix (as determined by
476 * whether {@link java.lang.Character#digit(char, int)} returns a
477 * nonnegative value), except that the first character may be an
478 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
479 * indicate a negative value or an ASCII plus sign {@code '+'}
480 * ({@code '\u005Cu002B'}) to indicate a positive value. The
481 * resulting integer value is returned.
482 *
483 * <p>An exception of type {@code NumberFormatException} is
484 * thrown if any of the following situations occurs:
485 * <ul>
486 * <li>The first argument is {@code null} or is a string of
487 * length zero.
488 *
489 * <li>The radix is either smaller than
490 * {@link java.lang.Character#MIN_RADIX} or
491 * larger than {@link java.lang.Character#MAX_RADIX}.
492 *
493 * <li>Any character of the string is not a digit of the specified
494 * radix, except that the first character may be a minus sign
495 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign
496 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
497 * string is longer than length 1.
498 *
499 * <li>The value represented by the string is not a value of type
500 * {@code int}.
501 * </ul>
502 *
503 * <p>Examples:
504 * <blockquote><pre>
505 * parseInt("0", 10) returns 0
506 * parseInt("473", 10) returns 473
507 * parseInt("+42", 10) returns 42
508 * parseInt("-0", 10) returns 0
509 * parseInt("-FF", 16) returns -255
510 * parseInt("1100110", 2) returns 102
511 * parseInt("2147483647", 10) returns 2147483647
512 * parseInt("-2147483648", 10) returns -2147483648
513 * parseInt("2147483648", 10) throws a NumberFormatException
514 * parseInt("99", 8) throws a NumberFormatException
515 * parseInt("Kona", 10) throws a NumberFormatException
516 * parseInt("Kona", 27) returns 411787
517 * </pre></blockquote>
518 *
519 * @param s the {@code String} containing the integer
520 * representation to be parsed
521 * @param radix the radix to be used while parsing {@code s}.
522 * @return the integer represented by the string argument in the
523 * specified radix.
524 * @throws NumberFormatException if the {@code String}
525 * does not contain a parsable {@code int}.
526 */
527 public static int parseInt(String s, int radix)
528 throws NumberFormatException {
529 /*
530 * WARNING: This method may be invoked early during VM initialization
531 * before IntegerCache is initialized. Care must be taken to not use
532 * the valueOf method.
533 */
534
535 if (s == null) {
536 throw new NumberFormatException("Cannot parse null string");
537 }
538
539 if (radix < Character.MIN_RADIX) {
540 throw new NumberFormatException(String.format(
541 "radix %s less than Character.MIN_RADIX", radix));
542 }
543
544 if (radix > Character.MAX_RADIX) {
545 throw new NumberFormatException(String.format(
546 "radix %s greater than Character.MAX_RADIX", radix));
547 }
548
549 int len = s.length();
550 if (len == 0) {
551 throw NumberFormatException.forInputString("", radix);
552 }
553 int digit = ~0xFF;
554 int i = 0;
555 char firstChar = s.charAt(i++);
556 if (firstChar != '-' && firstChar != '+') {
557 digit = digit(firstChar, radix);
558 }
559 if (digit >= 0 || digit == ~0xFF && len > 1) {
560 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
561 int multmin = limit / radix;
562 int result = -(digit & 0xFF);
563 boolean inRange = true;
564 /* Accumulating negatively avoids surprises near MAX_VALUE */
565 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
566 && (inRange = result > multmin
567 || result == multmin && digit <= radix * multmin - limit)) {
568 result = radix * result - digit;
569 }
570 if (inRange && i == len && digit >= 0) {
571 return firstChar != '-' ? -result : result;
572 }
573 }
574 throw NumberFormatException.forInputString(s, radix);
575 }
576
577 /**
578 * Parses the {@link CharSequence} argument as a signed {@code int} in the
579 * specified {@code radix}, beginning at the specified {@code beginIndex}
580 * and extending to {@code endIndex - 1}.
581 *
582 * <p>The method does not take steps to guard against the
583 * {@code CharSequence} being mutated while parsing.
584 *
585 * @param s the {@code CharSequence} containing the {@code int}
586 * representation to be parsed
587 * @param beginIndex the beginning index, inclusive.
588 * @param endIndex the ending index, exclusive.
589 * @param radix the radix to be used while parsing {@code s}.
590 * @return the signed {@code int} represented by the subsequence in
591 * the specified radix.
592 * @throws NullPointerException if {@code s} is null.
593 * @throws IndexOutOfBoundsException if {@code beginIndex} is
594 * negative, or if {@code beginIndex} is greater than
595 * {@code endIndex} or if {@code endIndex} is greater than
596 * {@code s.length()}.
597 * @throws NumberFormatException if the {@code CharSequence} does not
598 * contain a parsable {@code int} in the specified
599 * {@code radix}, or if {@code radix} is either smaller than
600 * {@link java.lang.Character#MIN_RADIX} or larger than
601 * {@link java.lang.Character#MAX_RADIX}.
602 * @since 9
603 */
604 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
605 throws NumberFormatException {
606 Objects.requireNonNull(s);
607 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
608
609 if (radix < Character.MIN_RADIX) {
610 throw new NumberFormatException(String.format(
611 "radix %s less than Character.MIN_RADIX", radix));
612 }
613
614 if (radix > Character.MAX_RADIX) {
615 throw new NumberFormatException(String.format(
616 "radix %s greater than Character.MAX_RADIX", radix));
617 }
618
619 /*
620 * While s can be concurrently modified, it is ensured that each
621 * of its characters is read at most once, from lower to higher indices.
622 * This is obtained by reading them using the pattern s.charAt(i++),
623 * and by not updating i anywhere else.
624 */
625 if (beginIndex == endIndex) {
626 throw NumberFormatException.forInputString("", radix);
627 }
628 int digit = ~0xFF;
629 int i = beginIndex;
630 char firstChar = s.charAt(i++);
631 if (firstChar != '-' && firstChar != '+') {
632 digit = digit(firstChar, radix);
633 }
634 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
635 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
636 int multmin = limit / radix;
637 int result = -(digit & 0xFF);
638 boolean inRange = true;
639 /* Accumulating negatively avoids surprises near MAX_VALUE */
640 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
641 && (inRange = result > multmin
642 || result == multmin && digit <= radix * multmin - limit)) {
643 result = radix * result - digit;
644 }
645 if (inRange && i == endIndex && digit >= 0) {
646 return firstChar != '-' ? -result : result;
647 }
648 }
649 throw NumberFormatException.forCharSequence(s, beginIndex,
650 endIndex, i - (digit < -1 ? 0 : 1));
651 }
652
653 /**
654 * Parses the string argument as a signed decimal integer. The
655 * characters in the string must all be decimal digits, except
656 * that the first character may be an ASCII minus sign {@code '-'}
657 * ({@code '\u005Cu002D'}) to indicate a negative value or an
658 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
659 * indicate a positive value. The resulting integer value is
660 * returned, exactly as if the argument and the radix 10 were
661 * given as arguments to the {@link #parseInt(java.lang.String,
662 * int)} method.
663 *
664 * @param s a {@code String} containing the {@code int}
665 * representation to be parsed
666 * @return the integer value represented by the argument in decimal.
667 * @throws NumberFormatException if the string does not contain a
668 * parsable integer.
669 */
670 public static int parseInt(String s) throws NumberFormatException {
671 return parseInt(s, 10);
672 }
673
674 /**
675 * Parses the string argument as an unsigned integer in the radix
676 * specified by the second argument. An unsigned integer maps the
677 * values usually associated with negative numbers to positive
678 * numbers larger than {@code MAX_VALUE}.
679 *
680 * The characters in the string must all be digits of the
681 * specified radix (as determined by whether {@link
682 * java.lang.Character#digit(char, int)} returns a nonnegative
683 * value), except that the first character may be an ASCII plus
684 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
685 * integer value is returned.
686 *
687 * <p>An exception of type {@code NumberFormatException} is
688 * thrown if any of the following situations occurs:
689 * <ul>
690 * <li>The first argument is {@code null} or is a string of
691 * length zero.
692 *
693 * <li>The radix is either smaller than
694 * {@link java.lang.Character#MIN_RADIX} or
695 * larger than {@link java.lang.Character#MAX_RADIX}.
696 *
697 * <li>Any character of the string is not a digit of the specified
698 * radix, except that the first character may be a plus sign
699 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
700 * string is longer than length 1.
701 *
702 * <li>The value represented by the string is larger than the
703 * largest unsigned {@code int}, 2<sup>32</sup>-1.
704 *
705 * </ul>
706 *
707 *
708 * @param s the {@code String} containing the unsigned integer
709 * representation to be parsed
710 * @param radix the radix to be used while parsing {@code s}.
711 * @return the integer represented by the string argument in the
712 * specified radix.
713 * @throws NumberFormatException if the {@code String}
714 * does not contain a parsable {@code int}.
715 * @since 1.8
716 */
717 public static int parseUnsignedInt(String s, int radix)
718 throws NumberFormatException {
719 if (s == null) {
720 throw new NumberFormatException("Cannot parse null string");
721 }
722
723 if (radix < Character.MIN_RADIX) {
724 throw new NumberFormatException(String.format(
725 "radix %s less than Character.MIN_RADIX", radix));
726 }
727
728 if (radix > Character.MAX_RADIX) {
729 throw new NumberFormatException(String.format(
730 "radix %s greater than Character.MAX_RADIX", radix));
731 }
732
733 int len = s.length();
734 if (len == 0) {
735 throw NumberFormatException.forInputString(s, radix);
736 }
737 int i = 0;
738 char firstChar = s.charAt(i++);
739 if (firstChar == '-') {
740 throw new NumberFormatException(String.format(
741 "Illegal leading minus sign on unsigned string %s.", s));
742 }
743 int digit = ~0xFF;
744 if (firstChar != '+') {
745 digit = digit(firstChar, radix);
746 }
747 if (digit >= 0 || digit == ~0xFF && len > 1) {
748 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
749 int result = digit & 0xFF;
750 boolean inRange = true;
751 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
752 && (inRange = compareUnsigned(result, multmax) < 0
753 || result == multmax && digit < -radix * multmax)) {
754 result = radix * result + digit;
755 }
756 if (inRange && i == len && digit >= 0) {
757 return result;
758 }
759 }
760 if (digit < 0) {
761 throw NumberFormatException.forInputString(s, radix);
762 }
763 throw new NumberFormatException(String.format(
764 "String value %s exceeds range of unsigned int.", s));
765 }
766
767 /**
768 * Parses the {@link CharSequence} argument as an unsigned {@code int} in
769 * the specified {@code radix}, beginning at the specified
770 * {@code beginIndex} and extending to {@code endIndex - 1}.
771 *
772 * <p>The method does not take steps to guard against the
773 * {@code CharSequence} being mutated while parsing.
774 *
775 * @param s the {@code CharSequence} containing the unsigned
776 * {@code int} representation to be parsed
777 * @param beginIndex the beginning index, inclusive.
778 * @param endIndex the ending index, exclusive.
779 * @param radix the radix to be used while parsing {@code s}.
780 * @return the unsigned {@code int} represented by the subsequence in
781 * the specified radix.
782 * @throws NullPointerException if {@code s} is null.
783 * @throws IndexOutOfBoundsException if {@code beginIndex} is
784 * negative, or if {@code beginIndex} is greater than
785 * {@code endIndex} or if {@code endIndex} is greater than
786 * {@code s.length()}.
787 * @throws NumberFormatException if the {@code CharSequence} does not
788 * contain a parsable unsigned {@code int} in the specified
789 * {@code radix}, or if {@code radix} is either smaller than
790 * {@link java.lang.Character#MIN_RADIX} or larger than
791 * {@link java.lang.Character#MAX_RADIX}.
792 * @since 9
793 */
794 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
795 throws NumberFormatException {
796 Objects.requireNonNull(s);
797 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
798
799 if (radix < Character.MIN_RADIX) {
800 throw new NumberFormatException(String.format(
801 "radix %s less than Character.MIN_RADIX", radix));
802 }
803
804 if (radix > Character.MAX_RADIX) {
805 throw new NumberFormatException(String.format(
806 "radix %s greater than Character.MAX_RADIX", radix));
807 }
808
809 /*
810 * While s can be concurrently modified, it is ensured that each
811 * of its characters is read at most once, from lower to higher indices.
812 * This is obtained by reading them using the pattern s.charAt(i++),
813 * and by not updating i anywhere else.
814 */
815 if (beginIndex == endIndex) {
816 throw NumberFormatException.forInputString("", radix);
817 }
818 int i = beginIndex;
819 char firstChar = s.charAt(i++);
820 if (firstChar == '-') {
821 throw new NumberFormatException(
822 "Illegal leading minus sign on unsigned string " + s + ".");
823 }
824 int digit = ~0xFF;
825 if (firstChar != '+') {
826 digit = digit(firstChar, radix);
827 }
828 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
829 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
830 int result = digit & 0xFF;
831 boolean inRange = true;
832 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
833 && (inRange = compareUnsigned(result, multmax) < 0
834 || result == multmax && digit < -radix * multmax)) {
835 result = radix * result + digit;
836 }
837 if (inRange && i == endIndex && digit >= 0) {
838 return result;
839 }
840 }
841 if (digit < 0) {
842 throw NumberFormatException.forCharSequence(s, beginIndex,
843 endIndex, i - (digit < -1 ? 0 : 1));
844 }
845 throw new NumberFormatException(String.format(
846 "String value %s exceeds range of unsigned int.", s));
847 }
848
849 /**
850 * Parses the string argument as an unsigned decimal integer. The
851 * characters in the string must all be decimal digits, except
852 * that the first character may be an ASCII plus sign {@code
853 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
854 * is returned, exactly as if the argument and the radix 10 were
855 * given as arguments to the {@link
856 * #parseUnsignedInt(java.lang.String, int)} method.
857 *
858 * @param s a {@code String} containing the unsigned {@code int}
859 * representation to be parsed
860 * @return the unsigned integer value represented by the argument in decimal.
861 * @throws NumberFormatException if the string does not contain a
862 * parsable unsigned integer.
863 * @since 1.8
864 */
865 public static int parseUnsignedInt(String s) throws NumberFormatException {
866 return parseUnsignedInt(s, 10);
867 }
868
869 /**
870 * Returns an {@code Integer} object holding the value
871 * extracted from the specified {@code String} when parsed
872 * with the radix given by the second argument. The first argument
873 * is interpreted as representing a signed integer in the radix
874 * specified by the second argument, exactly as if the arguments
875 * were given to the {@link #parseInt(java.lang.String, int)}
876 * method. The result is an {@code Integer} object that
877 * represents the integer value specified by the string.
878 *
879 * <p>In other words, this method returns an {@code Integer}
880 * object equal to the value of:
881 *
882 * <blockquote>
883 * {@code Integer.valueOf(Integer.parseInt(s, radix))}
884 * </blockquote>
885 *
886 * @param s the string to be parsed.
887 * @param radix the radix to be used in interpreting {@code s}
888 * @return an {@code Integer} object holding the value
889 * represented by the string argument in the specified
890 * radix.
891 * @throws NumberFormatException if the {@code String}
892 * does not contain a parsable {@code int}.
893 */
894 public static Integer valueOf(String s, int radix) throws NumberFormatException {
895 return Integer.valueOf(parseInt(s,radix));
896 }
897
898 /**
899 * Returns an {@code Integer} object holding the
900 * value of the specified {@code String}. The argument is
901 * interpreted as representing a signed decimal integer, exactly
902 * as if the argument were given to the {@link
903 * #parseInt(java.lang.String)} method. The result is an
904 * {@code Integer} object that represents the integer value
905 * specified by the string.
906 *
907 * <p>In other words, this method returns an {@code Integer}
908 * object equal to the value of:
909 *
910 * <blockquote>
911 * {@code Integer.valueOf(Integer.parseInt(s))}
912 * </blockquote>
913 *
914 * @param s the string to be parsed.
915 * @return an {@code Integer} object holding the value
916 * represented by the string argument.
917 * @throws NumberFormatException if the string cannot be parsed
918 * as an integer.
919 */
920 public static Integer valueOf(String s) throws NumberFormatException {
921 return Integer.valueOf(parseInt(s, 10));
922 }
923
924 /**
925 * Cache to support the object identity semantics of autoboxing for values between
926 * -128 and 127 (inclusive) as required by JLS.
927 *
928 * The cache is initialized on first usage. The size of the cache
929 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
930 * During VM initialization, java.lang.Integer.IntegerCache.high property
931 * may be set and saved in the private system properties in the
932 * jdk.internal.misc.VM class.
933 *
934 * WARNING: The cache is archived with CDS and reloaded from the shared
935 * archive at runtime. The archived cache (Integer[]) and Integer objects
936 * reside in the closed archive heap regions. Care should be taken when
937 * changing the implementation and the cache array should not be assigned
938 * with new Integer object(s) after initialization.
939 */
940
941 private static final class IntegerCache {
942 static final int low = -128;
943 static final int high;
944
945 @Stable
946 static final Integer[] cache;
947 static Integer[] archivedCache;
948
949 static {
950 // high value may be configured by property
951 int h = 127;
952 String integerCacheHighPropValue =
953 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
954 if (integerCacheHighPropValue != null) {
955 try {
956 h = Math.max(parseInt(integerCacheHighPropValue), 127);
957 // Maximum array size is Integer.MAX_VALUE
958 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
959 } catch( NumberFormatException nfe) {
960 // If the property cannot be parsed into an int, ignore it.
961 }
962 }
963 high = h;
964
965 // Load IntegerCache.archivedCache from archive, if possible
966 CDS.initializeFromArchive(IntegerCache.class);
967 int size = (high - low) + 1;
968
969 // Use the archived cache if it exists and is large enough
970 if (archivedCache == null || size > archivedCache.length) {
971 Integer[] c = new Integer[size];
972 int j = low;
973 // If archive has Integer cache, we must use all instances from it.
974 // Otherwise, the identity checks between archived Integers and
975 // runtime-cached Integers would fail.
976 int archivedSize = (archivedCache == null) ? 0 : archivedCache.length;
977 for (int i = 0; i < archivedSize; i++) {
978 c[i] = archivedCache[i];
979 assert j == archivedCache[i];
980 j++;
981 }
982 // Fill the rest of the cache.
983 for (int i = archivedSize; i < size; i++) {
984 c[i] = new Integer(j++);
985 }
986 archivedCache = c;
987 }
988 cache = archivedCache;
989 // range [-128, 127] must be interned (JLS7 5.1.7)
990 assert IntegerCache.high >= 127;
991 }
992
993 private IntegerCache() {}
994 }
995
996 /**
997 * Returns an {@code Integer} instance representing the specified
998 * {@code int} value. If a new {@code Integer} instance is not
999 * required, this method should generally be used in preference to
1000 * the constructor {@link #Integer(int)}, as this method is likely
1001 * to yield significantly better space and time performance by
1002 * caching frequently requested values.
1003 *
1004 * This method will always cache values in the range -128 to 127,
1005 * inclusive, and may cache other values outside of this range.
1006 *
1007 * @param i an {@code int} value.
1008 * @return an {@code Integer} instance representing {@code i}.
1009 * @since 1.5
1010 */
1011 @IntrinsicCandidate
1012 @DeserializeConstructor
1013 public static Integer valueOf(int i) {
1014 if (i >= IntegerCache.low && i <= IntegerCache.high)
1015 return IntegerCache.cache[i + (-IntegerCache.low)];
1016 return new Integer(i);
1017 }
1018
1019 /**
1020 * The value of the {@code Integer}.
1021 *
1022 * @serial
1023 */
1024 private final int value;
1025
1026 /**
1027 * Constructs a newly allocated {@code Integer} object that
1028 * represents the specified {@code int} value.
1029 *
1030 * @param value the value to be represented by the
1031 * {@code Integer} object.
1032 *
1033 * @deprecated
1034 * It is rarely appropriate to use this constructor. The static factory
1035 * {@link #valueOf(int)} is generally a better choice, as it is
1036 * likely to yield significantly better space and time performance.
1037 */
1038 @Deprecated(since="9", forRemoval = true)
1039 public Integer(int value) {
1040 this.value = value;
1041 }
1042
1043 /**
1044 * Constructs a newly allocated {@code Integer} object that
1045 * represents the {@code int} value indicated by the
1046 * {@code String} parameter. The string is converted to an
1047 * {@code int} value in exactly the manner used by the
1048 * {@code parseInt} method for radix 10.
1049 *
1050 * @param s the {@code String} to be converted to an {@code Integer}.
1051 * @throws NumberFormatException if the {@code String} does not
1052 * contain a parsable integer.
1053 *
1054 * @deprecated
1055 * It is rarely appropriate to use this constructor.
1056 * Use {@link #parseInt(String)} to convert a string to a
1057 * {@code int} primitive, or use {@link #valueOf(String)}
1058 * to convert a string to an {@code Integer} object.
1059 */
1060 @Deprecated(since="9", forRemoval = true)
1061 public Integer(String s) throws NumberFormatException {
1062 this.value = parseInt(s, 10);
1063 }
1064
1065 /**
1066 * Returns the value of this {@code Integer} as a {@code byte}
1067 * after a narrowing primitive conversion.
1068 * @jls 5.1.3 Narrowing Primitive Conversion
1069 */
1070 public byte byteValue() {
1071 return (byte)value;
1072 }
1073
1074 /**
1075 * Returns the value of this {@code Integer} as a {@code short}
1076 * after a narrowing primitive conversion.
1077 * @jls 5.1.3 Narrowing Primitive Conversion
1078 */
1079 public short shortValue() {
1080 return (short)value;
1081 }
1082
1083 /**
1084 * Returns the value of this {@code Integer} as an
1085 * {@code int}.
1086 */
1087 @IntrinsicCandidate
1088 public int intValue() {
1089 return value;
1090 }
1091
1092 /**
1093 * Returns the value of this {@code Integer} as a {@code long}
1094 * after a widening primitive conversion.
1095 * @jls 5.1.2 Widening Primitive Conversion
1096 * @see Integer#toUnsignedLong(int)
1097 */
1098 public long longValue() {
1099 return (long)value;
1100 }
1101
1102 /**
1103 * Returns the value of this {@code Integer} as a {@code float}
1104 * after a widening primitive conversion.
1105 * @jls 5.1.2 Widening Primitive Conversion
1106 */
1107 public float floatValue() {
1108 return (float)value;
1109 }
1110
1111 /**
1112 * Returns the value of this {@code Integer} as a {@code double}
1113 * after a widening primitive conversion.
1114 * @jls 5.1.2 Widening Primitive Conversion
1115 */
1116 public double doubleValue() {
1117 return (double)value;
1118 }
1119
1120 /**
1121 * Returns a {@code String} object representing this
1122 * {@code Integer}'s value. The value is converted to signed
1123 * decimal representation and returned as a string, exactly as if
1124 * the integer value were given as an argument to the {@link
1125 * java.lang.Integer#toString(int)} method.
1126 *
1127 * @return a string representation of the value of this object in
1128 * base 10.
1129 */
1130 public String toString() {
1131 return toString(value);
1132 }
1133
1134 /**
1135 * Returns a hash code for this {@code Integer}.
1136 *
1137 * @return a hash code value for this object, equal to the
1138 * primitive {@code int} value represented by this
1139 * {@code Integer} object.
1140 */
1141 @Override
1142 public int hashCode() {
1143 return Integer.hashCode(value);
1144 }
1145
1146 /**
1147 * Returns a hash code for an {@code int} value; compatible with
1148 * {@code Integer.hashCode()}.
1149 *
1150 * @param value the value to hash
1151 * @since 1.8
1152 *
1153 * @return a hash code value for an {@code int} value.
1154 */
1155 public static int hashCode(int value) {
1156 return value;
1157 }
1158
1159 /**
1160 * Compares this object to the specified object. The result is
1161 * {@code true} if and only if the argument is not
1162 * {@code null} and is an {@code Integer} object that
1163 * contains the same {@code int} value as this object.
1164 *
1165 * @param obj the object to compare with.
1166 * @return {@code true} if the objects are the same;
1167 * {@code false} otherwise.
1168 */
1169 public boolean equals(Object obj) {
1170 if (obj instanceof Integer i) {
1171 return value == i.intValue();
1172 }
1173 return false;
1174 }
1175
1176 /**
1177 * Determines the integer value of the system property with the
1178 * specified name.
1179 *
1180 * <p>The first argument is treated as the name of a system
1181 * property. System properties are accessible through the {@link
1182 * java.lang.System#getProperty(java.lang.String)} method. The
1183 * string value of this property is then interpreted as an integer
1184 * value using the grammar supported by {@link Integer#decode decode} and
1185 * an {@code Integer} object representing this value is returned.
1186 *
1187 * <p>If there is no property with the specified name, if the
1188 * specified name is empty or {@code null}, or if the property
1189 * does not have the correct numeric format, then {@code null} is
1190 * returned.
1191 *
1192 * <p>In other words, this method returns an {@code Integer}
1193 * object equal to the value of:
1194 *
1195 * <blockquote>
1196 * {@code getInteger(nm, null)}
1197 * </blockquote>
1198 *
1199 * @param nm property name.
1200 * @return the {@code Integer} value of the property.
1201 * @throws SecurityException for the same reasons as
1202 * {@link System#getProperty(String) System.getProperty}
1203 * @see java.lang.System#getProperty(java.lang.String)
1204 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1205 */
1206 public static Integer getInteger(String nm) {
1207 return getInteger(nm, null);
1208 }
1209
1210 /**
1211 * Determines the integer value of the system property with the
1212 * specified name.
1213 *
1214 * <p>The first argument is treated as the name of a system
1215 * property. System properties are accessible through the {@link
1216 * java.lang.System#getProperty(java.lang.String)} method. The
1217 * string value of this property is then interpreted as an integer
1218 * value using the grammar supported by {@link Integer#decode decode} and
1219 * an {@code Integer} object representing this value is returned.
1220 *
1221 * <p>The second argument is the default value. An {@code Integer} object
1222 * that represents the value of the second argument is returned if there
1223 * is no property of the specified name, if the property does not have
1224 * the correct numeric format, or if the specified name is empty or
1225 * {@code null}.
1226 *
1227 * <p>In other words, this method returns an {@code Integer} object
1228 * equal to the value of:
1229 *
1230 * <blockquote>
1231 * {@code getInteger(nm, Integer.valueOf(val))}
1232 * </blockquote>
1233 *
1234 * but in practice it may be implemented in a manner such as:
1235 *
1236 * <blockquote><pre>
1237 * Integer result = getInteger(nm, null);
1238 * return (result == null) ? Integer.valueOf(val) : result;
1239 * </pre></blockquote>
1240 *
1241 * to avoid the unnecessary allocation of an {@code Integer}
1242 * object when the default value is not needed.
1243 *
1244 * @param nm property name.
1245 * @param val default value.
1246 * @return the {@code Integer} value of the property.
1247 * @throws SecurityException for the same reasons as
1248 * {@link System#getProperty(String) System.getProperty}
1249 * @see java.lang.System#getProperty(java.lang.String)
1250 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1251 */
1252 public static Integer getInteger(String nm, int val) {
1253 Integer result = getInteger(nm, null);
1254 return (result == null) ? Integer.valueOf(val) : result;
1255 }
1256
1257 /**
1258 * Returns the integer value of the system property with the
1259 * specified name. The first argument is treated as the name of a
1260 * system property. System properties are accessible through the
1261 * {@link java.lang.System#getProperty(java.lang.String)} method.
1262 * The string value of this property is then interpreted as an
1263 * integer value, as per the {@link Integer#decode decode} method,
1264 * and an {@code Integer} object representing this value is
1265 * returned; in summary:
1266 *
1267 * <ul><li>If the property value begins with the two ASCII characters
1268 * {@code 0x} or the ASCII character {@code #}, not
1269 * followed by a minus sign, then the rest of it is parsed as a
1270 * hexadecimal integer exactly as by the method
1271 * {@link #valueOf(java.lang.String, int)} with radix 16.
1272 * <li>If the property value begins with the ASCII character
1273 * {@code 0} followed by another character, it is parsed as an
1274 * octal integer exactly as by the method
1275 * {@link #valueOf(java.lang.String, int)} with radix 8.
1276 * <li>Otherwise, the property value is parsed as a decimal integer
1277 * exactly as by the method {@link #valueOf(java.lang.String, int)}
1278 * with radix 10.
1279 * </ul>
1280 *
1281 * <p>The second argument is the default value. The default value is
1282 * returned if there is no property of the specified name, if the
1283 * property does not have the correct numeric format, or if the
1284 * specified name is empty or {@code null}.
1285 *
1286 * @param nm property name.
1287 * @param val default value.
1288 * @return the {@code Integer} value of the property.
1289 * @throws SecurityException for the same reasons as
1290 * {@link System#getProperty(String) System.getProperty}
1291 * @see System#getProperty(java.lang.String)
1292 * @see System#getProperty(java.lang.String, java.lang.String)
1293 */
1294 public static Integer getInteger(String nm, Integer val) {
1295 String v = null;
1296 try {
1297 v = System.getProperty(nm);
1298 } catch (IllegalArgumentException | NullPointerException e) {
1299 }
1300 if (v != null) {
1301 try {
1302 return Integer.decode(v);
1303 } catch (NumberFormatException e) {
1304 }
1305 }
1306 return val;
1307 }
1308
1309 /**
1310 * Decodes a {@code String} into an {@code Integer}.
1311 * Accepts decimal, hexadecimal, and octal numbers given
1312 * by the following grammar:
1313 *
1314 * <blockquote>
1315 * <dl>
1316 * <dt><i>DecodableString:</i>
1317 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1318 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1319 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1320 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1321 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1322 *
1323 * <dt><i>Sign:</i>
1324 * <dd>{@code -}
1325 * <dd>{@code +}
1326 * </dl>
1327 * </blockquote>
1328 *
1329 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1330 * are as defined in section {@jls 3.10.1} of
1331 * <cite>The Java Language Specification</cite>,
1332 * except that underscores are not accepted between digits.
1333 *
1334 * <p>The sequence of characters following an optional
1335 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1336 * "{@code #}", or leading zero) is parsed as by the {@code
1337 * Integer.parseInt} method with the indicated radix (10, 16, or
1338 * 8). This sequence of characters must represent a positive
1339 * value or a {@link NumberFormatException} will be thrown. The
1340 * result is negated if first character of the specified {@code
1341 * String} is the minus sign. No whitespace characters are
1342 * permitted in the {@code String}.
1343 *
1344 * @param nm the {@code String} to decode.
1345 * @return an {@code Integer} object holding the {@code int}
1346 * value represented by {@code nm}
1347 * @throws NumberFormatException if the {@code String} does not
1348 * contain a parsable integer.
1349 * @see java.lang.Integer#parseInt(java.lang.String, int)
1350 */
1351 public static Integer decode(String nm) throws NumberFormatException {
1352 int radix = 10;
1353 int index = 0;
1354 boolean negative = false;
1355 int result;
1356
1357 if (nm.isEmpty())
1358 throw new NumberFormatException("Zero length string");
1359 char firstChar = nm.charAt(0);
1360 // Handle sign, if present
1361 if (firstChar == '-') {
1362 negative = true;
1363 index++;
1364 } else if (firstChar == '+')
1365 index++;
1366
1367 // Handle radix specifier, if present
1368 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1369 index += 2;
1370 radix = 16;
1371 }
1372 else if (nm.startsWith("#", index)) {
1373 index ++;
1374 radix = 16;
1375 }
1376 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1377 index ++;
1378 radix = 8;
1379 }
1380
1381 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1382 throw new NumberFormatException("Sign character in wrong position");
1383
1384 try {
1385 result = parseInt(nm, index, nm.length(), radix);
1386 result = negative ? -result : result;
1387 } catch (NumberFormatException e) {
1388 // If number is Integer.MIN_VALUE, we'll end up here. The next line
1389 // handles this case, and causes any genuine format error to be
1390 // rethrown.
1391 String constant = negative ? ("-" + nm.substring(index))
1392 : nm.substring(index);
1393 result = parseInt(constant, radix);
1394 }
1395 return result;
1396 }
1397
1398 /**
1399 * Compares two {@code Integer} objects numerically.
1400 *
1401 * @param anotherInteger the {@code Integer} to be compared.
1402 * @return the value {@code 0} if this {@code Integer} is
1403 * equal to the argument {@code Integer}; a value less than
1404 * {@code 0} if this {@code Integer} is numerically less
1405 * than the argument {@code Integer}; and a value greater
1406 * than {@code 0} if this {@code Integer} is numerically
1407 * greater than the argument {@code Integer} (signed
1408 * comparison).
1409 * @since 1.2
1410 */
1411 public int compareTo(Integer anotherInteger) {
1412 return compare(this.value, anotherInteger.value);
1413 }
1414
1415 /**
1416 * Compares two {@code int} values numerically.
1417 * The value returned is identical to what would be returned by:
1418 * <pre>
1419 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1420 * </pre>
1421 *
1422 * @param x the first {@code int} to compare
1423 * @param y the second {@code int} to compare
1424 * @return the value {@code 0} if {@code x == y};
1425 * a value less than {@code 0} if {@code x < y}; and
1426 * a value greater than {@code 0} if {@code x > y}
1427 * @since 1.7
1428 */
1429 public static int compare(int x, int y) {
1430 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1431 }
1432
1433 /**
1434 * Compares two {@code int} values numerically treating the values
1435 * as unsigned.
1436 *
1437 * @param x the first {@code int} to compare
1438 * @param y the second {@code int} to compare
1439 * @return the value {@code 0} if {@code x == y}; a value less
1440 * than {@code 0} if {@code x < y} as unsigned values; and
1441 * a value greater than {@code 0} if {@code x > y} as
1442 * unsigned values
1443 * @since 1.8
1444 */
1445 @IntrinsicCandidate
1446 public static int compareUnsigned(int x, int y) {
1447 return compare(x + MIN_VALUE, y + MIN_VALUE);
1448 }
1449
1450 /**
1451 * Converts the argument to a {@code long} by an unsigned
1452 * conversion. In an unsigned conversion to a {@code long}, the
1453 * high-order 32 bits of the {@code long} are zero and the
1454 * low-order 32 bits are equal to the bits of the integer
1455 * argument.
1456 *
1457 * Consequently, zero and positive {@code int} values are mapped
1458 * to a numerically equal {@code long} value and negative {@code
1459 * int} values are mapped to a {@code long} value equal to the
1460 * input plus 2<sup>32</sup>.
1461 *
1462 * @param x the value to convert to an unsigned {@code long}
1463 * @return the argument converted to {@code long} by an unsigned
1464 * conversion
1465 * @since 1.8
1466 */
1467 public static long toUnsignedLong(int x) {
1468 return ((long) x) & 0xffffffffL;
1469 }
1470
1471 /**
1472 * Returns the unsigned quotient of dividing the first argument by
1473 * the second where each argument and the result is interpreted as
1474 * an unsigned value.
1475 *
1476 * <p>Note that in two's complement arithmetic, the three other
1477 * basic arithmetic operations of add, subtract, and multiply are
1478 * bit-wise identical if the two operands are regarded as both
1479 * being signed or both being unsigned. Therefore separate {@code
1480 * addUnsigned}, etc. methods are not provided.
1481 *
1482 * @param dividend the value to be divided
1483 * @param divisor the value doing the dividing
1484 * @return the unsigned quotient of the first argument divided by
1485 * the second argument
1486 * @see #remainderUnsigned
1487 * @since 1.8
1488 */
1489 @IntrinsicCandidate
1490 public static int divideUnsigned(int dividend, int divisor) {
1491 // In lieu of tricky code, for now just use long arithmetic.
1492 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor));
1493 }
1494
1495 /**
1496 * Returns the unsigned remainder from dividing the first argument
1497 * by the second where each argument and the result is interpreted
1498 * as an unsigned value.
1499 *
1500 * @param dividend the value to be divided
1501 * @param divisor the value doing the dividing
1502 * @return the unsigned remainder of the first argument divided by
1503 * the second argument
1504 * @see #divideUnsigned
1505 * @since 1.8
1506 */
1507 @IntrinsicCandidate
1508 public static int remainderUnsigned(int dividend, int divisor) {
1509 // In lieu of tricky code, for now just use long arithmetic.
1510 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor));
1511 }
1512
1513
1514 // Bit twiddling
1515
1516 /**
1517 * The number of bits used to represent an {@code int} value in two's
1518 * complement binary form.
1519 *
1520 * @since 1.5
1521 */
1522 @Native public static final int SIZE = 32;
1523
1524 /**
1525 * The number of bytes used to represent an {@code int} value in two's
1526 * complement binary form.
1527 *
1528 * @since 1.8
1529 */
1530 public static final int BYTES = SIZE / Byte.SIZE;
1531
1532 /**
1533 * Returns an {@code int} value with at most a single one-bit, in the
1534 * position of the highest-order ("leftmost") one-bit in the specified
1535 * {@code int} value. Returns zero if the specified value has no
1536 * one-bits in its two's complement binary representation, that is, if it
1537 * is equal to zero.
1538 *
1539 * @param i the value whose highest one bit is to be computed
1540 * @return an {@code int} value with a single one-bit, in the position
1541 * of the highest-order one-bit in the specified value, or zero if
1542 * the specified value is itself equal to zero.
1543 * @since 1.5
1544 */
1545 public static int highestOneBit(int i) {
1546 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1547 }
1548
1549 /**
1550 * Returns an {@code int} value with at most a single one-bit, in the
1551 * position of the lowest-order ("rightmost") one-bit in the specified
1552 * {@code int} value. Returns zero if the specified value has no
1553 * one-bits in its two's complement binary representation, that is, if it
1554 * is equal to zero.
1555 *
1556 * @param i the value whose lowest one bit is to be computed
1557 * @return an {@code int} value with a single one-bit, in the position
1558 * of the lowest-order one-bit in the specified value, or zero if
1559 * the specified value is itself equal to zero.
1560 * @since 1.5
1561 */
1562 public static int lowestOneBit(int i) {
1563 // HD, Section 2-1
1564 return i & -i;
1565 }
1566
1567 /**
1568 * Returns the number of zero bits preceding the highest-order
1569 * ("leftmost") one-bit in the two's complement binary representation
1570 * of the specified {@code int} value. Returns 32 if the
1571 * specified value has no one-bits in its two's complement representation,
1572 * in other words if it is equal to zero.
1573 *
1574 * <p>Note that this method is closely related to the logarithm base 2.
1575 * For all positive {@code int} values x:
1576 * <ul>
1577 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1578 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1579 * </ul>
1580 *
1581 * @param i the value whose number of leading zeros is to be computed
1582 * @return the number of zero bits preceding the highest-order
1583 * ("leftmost") one-bit in the two's complement binary representation
1584 * of the specified {@code int} value, or 32 if the value
1585 * is equal to zero.
1586 * @since 1.5
1587 */
1588 @IntrinsicCandidate
1589 public static int numberOfLeadingZeros(int i) {
1590 // HD, Count leading 0's
1591 if (i <= 0)
1592 return i == 0 ? 32 : 0;
1593 int n = 31;
1594 if (i >= 1 << 16) { n -= 16; i >>>= 16; }
1595 if (i >= 1 << 8) { n -= 8; i >>>= 8; }
1596 if (i >= 1 << 4) { n -= 4; i >>>= 4; }
1597 if (i >= 1 << 2) { n -= 2; i >>>= 2; }
1598 return n - (i >>> 1);
1599 }
1600
1601 /**
1602 * Returns the number of zero bits following the lowest-order ("rightmost")
1603 * one-bit in the two's complement binary representation of the specified
1604 * {@code int} value. Returns 32 if the specified value has no
1605 * one-bits in its two's complement representation, in other words if it is
1606 * equal to zero.
1607 *
1608 * @param i the value whose number of trailing zeros is to be computed
1609 * @return the number of zero bits following the lowest-order ("rightmost")
1610 * one-bit in the two's complement binary representation of the
1611 * specified {@code int} value, or 32 if the value is equal
1612 * to zero.
1613 * @since 1.5
1614 */
1615 @IntrinsicCandidate
1616 public static int numberOfTrailingZeros(int i) {
1617 // HD, Count trailing 0's
1618 i = ~i & (i - 1);
1619 if (i <= 0) return i & 32;
1620 int n = 1;
1621 if (i > 1 << 16) { n += 16; i >>>= 16; }
1622 if (i > 1 << 8) { n += 8; i >>>= 8; }
1623 if (i > 1 << 4) { n += 4; i >>>= 4; }
1624 if (i > 1 << 2) { n += 2; i >>>= 2; }
1625 return n + (i >>> 1);
1626 }
1627
1628 /**
1629 * Returns the number of one-bits in the two's complement binary
1630 * representation of the specified {@code int} value. This function is
1631 * sometimes referred to as the <i>population count</i>.
1632 *
1633 * @param i the value whose bits are to be counted
1634 * @return the number of one-bits in the two's complement binary
1635 * representation of the specified {@code int} value.
1636 * @since 1.5
1637 */
1638 @IntrinsicCandidate
1639 public static int bitCount(int i) {
1640 // HD, Figure 5-2
1641 i = i - ((i >>> 1) & 0x55555555);
1642 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1643 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1644 i = i + (i >>> 8);
1645 i = i + (i >>> 16);
1646 return i & 0x3f;
1647 }
1648
1649 /**
1650 * Returns the value obtained by rotating the two's complement binary
1651 * representation of the specified {@code int} value left by the
1652 * specified number of bits. (Bits shifted out of the left hand, or
1653 * high-order, side reenter on the right, or low-order.)
1654 *
1655 * <p>Note that left rotation with a negative distance is equivalent to
1656 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1657 * distance)}. Note also that rotation by any multiple of 32 is a
1658 * no-op, so all but the last five bits of the rotation distance can be
1659 * ignored, even if the distance is negative: {@code rotateLeft(val,
1660 * distance) == rotateLeft(val, distance & 0x1F)}.
1661 *
1662 * @param i the value whose bits are to be rotated left
1663 * @param distance the number of bit positions to rotate left
1664 * @return the value obtained by rotating the two's complement binary
1665 * representation of the specified {@code int} value left by the
1666 * specified number of bits.
1667 * @since 1.5
1668 */
1669 public static int rotateLeft(int i, int distance) {
1670 return (i << distance) | (i >>> -distance);
1671 }
1672
1673 /**
1674 * Returns the value obtained by rotating the two's complement binary
1675 * representation of the specified {@code int} value right by the
1676 * specified number of bits. (Bits shifted out of the right hand, or
1677 * low-order, side reenter on the left, or high-order.)
1678 *
1679 * <p>Note that right rotation with a negative distance is equivalent to
1680 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1681 * distance)}. Note also that rotation by any multiple of 32 is a
1682 * no-op, so all but the last five bits of the rotation distance can be
1683 * ignored, even if the distance is negative: {@code rotateRight(val,
1684 * distance) == rotateRight(val, distance & 0x1F)}.
1685 *
1686 * @param i the value whose bits are to be rotated right
1687 * @param distance the number of bit positions to rotate right
1688 * @return the value obtained by rotating the two's complement binary
1689 * representation of the specified {@code int} value right by the
1690 * specified number of bits.
1691 * @since 1.5
1692 */
1693 public static int rotateRight(int i, int distance) {
1694 return (i >>> distance) | (i << -distance);
1695 }
1696
1697 /**
1698 * Returns the value obtained by reversing the order of the bits in the
1699 * two's complement binary representation of the specified {@code int}
1700 * value.
1701 *
1702 * @param i the value to be reversed
1703 * @return the value obtained by reversing order of the bits in the
1704 * specified {@code int} value.
1705 * @since 1.5
1706 */
1707 @IntrinsicCandidate
1708 public static int reverse(int i) {
1709 // HD, Figure 7-1
1710 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1711 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1712 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1713
1714 return reverseBytes(i);
1715 }
1716
1717 /**
1718 * Returns the value obtained by compressing the bits of the
1719 * specified {@code int} value, {@code i}, in accordance with
1720 * the specified bit mask.
1721 * <p>
1722 * For each one-bit value {@code mb} of the mask, from least
1723 * significant to most significant, the bit value of {@code i} at
1724 * the same bit location as {@code mb} is assigned to the compressed
1725 * value contiguously starting from the least significant bit location.
1726 * All the upper remaining bits of the compressed value are set
1727 * to zero.
1728 *
1729 * @apiNote
1730 * Consider the simple case of compressing the digits of a hexadecimal
1731 * value:
1732 * {@snippet lang="java" :
1733 * // Compressing drink to food
1734 * compress(0xCAFEBABE, 0xFF00FFF0) == 0xCABAB
1735 * }
1736 * Starting from the least significant hexadecimal digit at position 0
1737 * from the right, the mask {@code 0xFF00FFF0} selects hexadecimal digits
1738 * at positions 1, 2, 3, 6 and 7 of {@code 0xCAFEBABE}. The selected digits
1739 * occur in the resulting compressed value contiguously from digit position
1740 * 0 in the same order.
1741 * <p>
1742 * The following identities all return {@code true} and are helpful to
1743 * understand the behaviour of {@code compress}:
1744 * {@snippet lang="java" :
1745 * // Returns 1 if the bit at position n is one
1746 * compress(x, 1 << n) == (x >> n & 1)
1747 *
1748 * // Logical shift right
1749 * compress(x, -1 << n) == x >>> n
1750 *
1751 * // Any bits not covered by the mask are ignored
1752 * compress(x, m) == compress(x & m, m)
1753 *
1754 * // Compressing a value by itself
1755 * compress(m, m) == (m == -1 || m == 0) ? m : (1 << bitCount(m)) - 1
1756 *
1757 * // Expanding then compressing with the same mask
1758 * compress(expand(x, m), m) == x & compress(m, m)
1759 * }
1760 * <p>
1761 * The Sheep And Goats (SAG) operation (see Hacker's Delight, Second Edition, section 7.7)
1762 * can be implemented as follows:
1763 * {@snippet lang="java" :
1764 * int compressLeft(int i, int mask) {
1765 * // This implementation follows the description in Hacker's Delight which
1766 * // is informative. A more optimal implementation is:
1767 * // Integer.compress(i, mask) << -Integer.bitCount(mask)
1768 * return Integer.reverse(
1769 * Integer.compress(Integer.reverse(i), Integer.reverse(mask)));
1770 * }
1771 *
1772 * int sag(int i, int mask) {
1773 * return compressLeft(i, mask) | Integer.compress(i, ~mask);
1774 * }
1775 *
1776 * // Separate the sheep from the goats
1777 * sag(0xCAFEBABE, 0xFF00FFF0) == 0xCABABFEE
1778 * }
1779 *
1780 * @param i the value whose bits are to be compressed
1781 * @param mask the bit mask
1782 * @return the compressed value
1783 * @see #expand
1784 * @since 19
1785 */
1786 @IntrinsicCandidate
1787 public static int compress(int i, int mask) {
1788 // See Hacker's Delight (2nd ed) section 7.4 Compress, or Generalized Extract
1789
1790 i = i & mask; // Clear irrelevant bits
1791 int maskCount = ~mask << 1; // Count 0's to right
1792
1793 for (int j = 0; j < 5; j++) {
1794 // Parallel prefix
1795 // Mask prefix identifies bits of the mask that have an odd number of 0's to the right
1796 int maskPrefix = parallelSuffix(maskCount);
1797 // Bits to move
1798 int maskMove = maskPrefix & mask;
1799 // Compress mask
1800 mask = (mask ^ maskMove) | (maskMove >>> (1 << j));
1801 // Bits of i to be moved
1802 int t = i & maskMove;
1803 // Compress i
1804 i = (i ^ t) | (t >>> (1 << j));
1805 // Adjust the mask count by identifying bits that have 0 to the right
1806 maskCount = maskCount & ~maskPrefix;
1807 }
1808 return i;
1809 }
1810
1811 /**
1812 * Returns the value obtained by expanding the bits of the
1813 * specified {@code int} value, {@code i}, in accordance with
1814 * the specified bit mask.
1815 * <p>
1816 * For each one-bit value {@code mb} of the mask, from least
1817 * significant to most significant, the next contiguous bit value
1818 * of {@code i} starting at the least significant bit is assigned
1819 * to the expanded value at the same bit location as {@code mb}.
1820 * All other remaining bits of the expanded value are set to zero.
1821 *
1822 * @apiNote
1823 * Consider the simple case of expanding the digits of a hexadecimal
1824 * value:
1825 * {@snippet lang="java" :
1826 * expand(0x0000CABAB, 0xFF00FFF0) == 0xCA00BAB0
1827 * }
1828 * Starting from the least significant hexadecimal digit at position 0
1829 * from the right, the mask {@code 0xFF00FFF0} selects the first five
1830 * hexadecimal digits of {@code 0x0000CABAB}. The selected digits occur
1831 * in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.
1832 * <p>
1833 * The following identities all return {@code true} and are helpful to
1834 * understand the behaviour of {@code expand}:
1835 * {@snippet lang="java" :
1836 * // Logically shift right the bit at position 0
1837 * expand(x, 1 << n) == (x & 1) << n
1838 *
1839 * // Logically shift right
1840 * expand(x, -1 << n) == x << n
1841 *
1842 * // Expanding all bits returns the mask
1843 * expand(-1, m) == m
1844 *
1845 * // Any bits not covered by the mask are ignored
1846 * expand(x, m) == expand(x, m) & m
1847 *
1848 * // Compressing then expanding with the same mask
1849 * expand(compress(x, m), m) == x & m
1850 * }
1851 * <p>
1852 * The select operation for determining the position of the one-bit with
1853 * index {@code n} in a {@code int} value can be implemented as follows:
1854 * {@snippet lang="java" :
1855 * int select(int i, int n) {
1856 * // the one-bit in i (the mask) with index n
1857 * int nthBit = Integer.expand(1 << n, i);
1858 * // the bit position of the one-bit with index n
1859 * return Integer.numberOfTrailingZeros(nthBit);
1860 * }
1861 *
1862 * // The one-bit with index 0 is at bit position 1
1863 * select(0b10101010_10101010, 0) == 1
1864 * // The one-bit with index 3 is at bit position 7
1865 * select(0b10101010_10101010, 3) == 7
1866 * }
1867 *
1868 * @param i the value whose bits are to be expanded
1869 * @param mask the bit mask
1870 * @return the expanded value
1871 * @see #compress
1872 * @since 19
1873 */
1874 @IntrinsicCandidate
1875 public static int expand(int i, int mask) {
1876 // Save original mask
1877 int originalMask = mask;
1878 // Count 0's to right
1879 int maskCount = ~mask << 1;
1880 int maskPrefix = parallelSuffix(maskCount);
1881 // Bits to move
1882 int maskMove1 = maskPrefix & mask;
1883 // Compress mask
1884 mask = (mask ^ maskMove1) | (maskMove1 >>> (1 << 0));
1885 maskCount = maskCount & ~maskPrefix;
1886
1887 maskPrefix = parallelSuffix(maskCount);
1888 // Bits to move
1889 int maskMove2 = maskPrefix & mask;
1890 // Compress mask
1891 mask = (mask ^ maskMove2) | (maskMove2 >>> (1 << 1));
1892 maskCount = maskCount & ~maskPrefix;
1893
1894 maskPrefix = parallelSuffix(maskCount);
1895 // Bits to move
1896 int maskMove3 = maskPrefix & mask;
1897 // Compress mask
1898 mask = (mask ^ maskMove3) | (maskMove3 >>> (1 << 2));
1899 maskCount = maskCount & ~maskPrefix;
1900
1901 maskPrefix = parallelSuffix(maskCount);
1902 // Bits to move
1903 int maskMove4 = maskPrefix & mask;
1904 // Compress mask
1905 mask = (mask ^ maskMove4) | (maskMove4 >>> (1 << 3));
1906 maskCount = maskCount & ~maskPrefix;
1907
1908 maskPrefix = parallelSuffix(maskCount);
1909 // Bits to move
1910 int maskMove5 = maskPrefix & mask;
1911
1912 int t = i << (1 << 4);
1913 i = (i & ~maskMove5) | (t & maskMove5);
1914 t = i << (1 << 3);
1915 i = (i & ~maskMove4) | (t & maskMove4);
1916 t = i << (1 << 2);
1917 i = (i & ~maskMove3) | (t & maskMove3);
1918 t = i << (1 << 1);
1919 i = (i & ~maskMove2) | (t & maskMove2);
1920 t = i << (1 << 0);
1921 i = (i & ~maskMove1) | (t & maskMove1);
1922
1923 // Clear irrelevant bits
1924 return i & originalMask;
1925 }
1926
1927 @ForceInline
1928 private static int parallelSuffix(int maskCount) {
1929 int maskPrefix = maskCount ^ (maskCount << 1);
1930 maskPrefix = maskPrefix ^ (maskPrefix << 2);
1931 maskPrefix = maskPrefix ^ (maskPrefix << 4);
1932 maskPrefix = maskPrefix ^ (maskPrefix << 8);
1933 maskPrefix = maskPrefix ^ (maskPrefix << 16);
1934 return maskPrefix;
1935 }
1936
1937 /**
1938 * Returns the signum function of the specified {@code int} value. (The
1939 * return value is -1 if the specified value is negative; 0 if the
1940 * specified value is zero; and 1 if the specified value is positive.)
1941 *
1942 * @param i the value whose signum is to be computed
1943 * @return the signum function of the specified {@code int} value.
1944 * @since 1.5
1945 */
1946 public static int signum(int i) {
1947 // HD, Section 2-7
1948 return (i >> 31) | (-i >>> 31);
1949 }
1950
1951 /**
1952 * Returns the value obtained by reversing the order of the bytes in the
1953 * two's complement representation of the specified {@code int} value.
1954 *
1955 * @param i the value whose bytes are to be reversed
1956 * @return the value obtained by reversing the bytes in the specified
1957 * {@code int} value.
1958 * @since 1.5
1959 */
1960 @IntrinsicCandidate
1961 public static int reverseBytes(int i) {
1962 return (i << 24) |
1963 ((i & 0xff00) << 8) |
1964 ((i >>> 8) & 0xff00) |
1965 (i >>> 24);
1966 }
1967
1968 /**
1969 * Adds two integers together as per the + operator.
1970 *
1971 * @param a the first operand
1972 * @param b the second operand
1973 * @return the sum of {@code a} and {@code b}
1974 * @see java.util.function.BinaryOperator
1975 * @since 1.8
1976 */
1977 public static int sum(int a, int b) {
1978 return a + b;
1979 }
1980
1981 /**
1982 * Returns the greater of two {@code int} values
1983 * as if by calling {@link Math#max(int, int) Math.max}.
1984 *
1985 * @param a the first operand
1986 * @param b the second operand
1987 * @return the greater of {@code a} and {@code b}
1988 * @see java.util.function.BinaryOperator
1989 * @since 1.8
1990 */
1991 public static int max(int a, int b) {
1992 return Math.max(a, b);
1993 }
1994
1995 /**
1996 * Returns the smaller of two {@code int} values
1997 * as if by calling {@link Math#min(int, int) Math.min}.
1998 *
1999 * @param a the first operand
2000 * @param b the second operand
2001 * @return the smaller of {@code a} and {@code b}
2002 * @see java.util.function.BinaryOperator
2003 * @since 1.8
2004 */
2005 public static int min(int a, int b) {
2006 return Math.min(a, b);
2007 }
2008
2009 /**
2010 * Returns an {@link Optional} containing the nominal descriptor for this
2011 * instance, which is the instance itself.
2012 *
2013 * @return an {@link Optional} describing the {@linkplain Integer} instance
2014 * @since 12
2015 */
2016 @Override
2017 public Optional<Integer> describeConstable() {
2018 return Optional.of(this);
2019 }
2020
2021 /**
2022 * Resolves this instance as a {@link ConstantDesc}, the result of which is
2023 * the instance itself.
2024 *
2025 * @param lookup ignored
2026 * @return the {@linkplain Integer} instance
2027 * @since 12
2028 */
2029 @Override
2030 public Integer resolveConstantDesc(MethodHandles.Lookup lookup) {
2031 return this;
2032 }
2033
2034 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2035 @java.io.Serial
2036 @Native private static final long serialVersionUID = 1360826667806852920L;
2037 }