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.vm.annotation.ForceInline;
32 import jdk.internal.vm.annotation.IntrinsicCandidate;
33 import jdk.internal.vm.annotation.Stable;
34
35 import java.lang.annotation.Native;
36 import java.lang.constant.Constable;
37 import java.lang.constant.ConstantDesc;
38 import java.lang.invoke.MethodHandles;
39 import java.util.Objects;
40 import java.util.Optional;
41
42 import static java.lang.Character.digit;
43 import static java.lang.String.COMPACT_STRINGS;
44 import static java.lang.String.LATIN1;
45 import static java.lang.String.UTF16;
46
47 /**
48 * The {@code Integer} class is the {@linkplain
49 * java.lang##wrapperClass wrapper class} for values of the primitive
50 * type {@code int}. An object of type {@code Integer} contains a
51 * single field whose type is {@code int}.
52 *
53 * <p>In addition, this class provides several methods for converting
54 * an {@code int} to a {@code String} and a {@code String} to an
55 * {@code int}, as well as other constants and methods useful when
56 * dealing with an {@code int}.
57 *
58 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
59 * class; programmers should treat instances that are
60 * {@linkplain #equals(Object) equal} as interchangeable and should not
61 * use instances for synchronization, or unpredictable behavior may
62 * occur. For example, in a future release, synchronization may fail.
63 *
64 * <p>Implementation note: The implementations of the "bit twiddling"
65 * methods (such as {@link #highestOneBit(int) highestOneBit} and
66 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
67 * based on material from Henry S. Warren, Jr.'s <cite>Hacker's
68 * Delight</cite>, (Addison Wesley, 2002) and <cite>Hacker's
69 * Delight, Second Edition</cite>, (Pearson Education, 2013).
70 *
71 * @author Lee Boynton
72 * @author Arthur van Hoff
73 * @author Josh Bloch
74 * @author Joseph D. Darcy
75 * @since 1.0
76 */
77 @jdk.internal.ValueBased
78 public final class Integer extends Number
79 implements Comparable<Integer>, Constable, ConstantDesc {
80 /**
81 * A constant holding the minimum value an {@code int} can
82 * have, -2<sup>31</sup>.
83 */
84 @Native public static final int MIN_VALUE = 0x80000000;
85
86 /**
87 * A constant holding the maximum value an {@code int} can
88 * have, 2<sup>31</sup>-1.
89 */
90 @Native public static final int MAX_VALUE = 0x7fffffff;
91
92 /**
93 * The {@code Class} instance representing the primitive type
94 * {@code int}.
95 *
96 * @since 1.1
97 */
98 public static final Class<Integer> TYPE = Class.getPrimitiveClass("int");
99
100 /**
101 * All possible chars for representing a number as a String
102 */
103 static final char[] digits = {
104 '0' , '1' , '2' , '3' , '4' , '5' ,
105 '6' , '7' , '8' , '9' , 'a' , 'b' ,
106 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
107 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
108 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
109 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
110 };
111
112 /**
113 * Returns a string representation of the first argument in the
114 * radix specified by the second argument.
115 *
116 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
117 * or larger than {@code Character.MAX_RADIX}, then the radix
118 * {@code 10} is used instead.
119 *
120 * <p>If the first argument is negative, the first element of the
121 * result is the ASCII minus character {@code '-'}
122 * ({@code '\u005Cu002D'}). If the first argument is not
123 * negative, no sign character appears in the result.
124 *
125 * <p>The remaining characters of the result represent the magnitude
126 * of the first argument. If the magnitude is zero, it is
127 * represented by a single zero character {@code '0'}
128 * ({@code '\u005Cu0030'}); otherwise, the first character of
129 * the representation of the magnitude will not be the zero
130 * character. The following ASCII characters are used as digits:
131 *
132 * <blockquote>
133 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
134 * </blockquote>
135 *
136 * These are {@code '\u005Cu0030'} through
137 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
138 * {@code '\u005Cu007A'}. If {@code radix} is
139 * <var>N</var>, then the first <var>N</var> of these characters
140 * are used as radix-<var>N</var> digits in the order shown. Thus,
141 * the digits for hexadecimal (radix 16) are
142 * {@code 0123456789abcdef}. If uppercase letters are
143 * desired, the {@link java.lang.String#toUpperCase()} method may
144 * be called on the result:
145 *
146 * <blockquote>
147 * {@code Integer.toString(n, 16).toUpperCase()}
148 * </blockquote>
149 *
150 * @param i an integer to be converted to a string.
151 * @param radix the radix to use in the string representation.
152 * @return a string representation of the argument in the specified radix.
153 * @see java.lang.Character#MAX_RADIX
154 * @see java.lang.Character#MIN_RADIX
155 */
156 public static String toString(int i, int radix) {
157 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
158 radix = 10;
159
160 /* Use the faster version */
161 if (radix == 10) {
162 return toString(i);
163 }
164
165 if (COMPACT_STRINGS) {
166 byte[] buf = new byte[33];
167 boolean negative = (i < 0);
168 int charPos = 32;
169
170 if (!negative) {
171 i = -i;
172 }
173
174 while (i <= -radix) {
175 buf[charPos--] = (byte)digits[-(i % radix)];
176 i = i / radix;
177 }
178 buf[charPos] = (byte)digits[-i];
179
180 if (negative) {
181 buf[--charPos] = '-';
182 }
183
184 return StringLatin1.newString(buf, charPos, (33 - charPos));
185 }
186 return toStringUTF16(i, radix);
187 }
188
189 private static String toStringUTF16(int i, int radix) {
190 byte[] buf = new byte[33 * 2];
191 boolean negative = (i < 0);
192 int charPos = 32;
193 if (!negative) {
194 i = -i;
195 }
196 while (i <= -radix) {
197 StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
198 i = i / radix;
199 }
200 StringUTF16.putChar(buf, charPos, digits[-i]);
201
202 if (negative) {
203 StringUTF16.putChar(buf, --charPos, '-');
204 }
205 return StringUTF16.newString(buf, charPos, (33 - charPos));
206 }
207
208 /**
209 * Returns a string representation of the first argument as an
210 * unsigned integer value in the radix specified by the second
211 * argument.
212 *
213 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
214 * or larger than {@code Character.MAX_RADIX}, then the radix
215 * {@code 10} is used instead.
216 *
217 * <p>Note that since the first argument is treated as an unsigned
218 * value, no leading sign character is printed.
219 *
220 * <p>If the magnitude is zero, it is represented by a single zero
221 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
222 * the first character of the representation of the magnitude will
223 * not be the zero character.
224 *
225 * <p>The behavior of radixes and the characters used as digits
226 * are the same as {@link #toString(int, int) toString}.
227 *
228 * @param i an integer to be converted to an unsigned string.
229 * @param radix the radix to use in the string representation.
230 * @return an unsigned string representation of the argument in the specified radix.
231 * @see #toString(int, int)
232 * @since 1.8
233 */
234 public static String toUnsignedString(int i, int radix) {
235 return Long.toUnsignedString(toUnsignedLong(i), radix);
236 }
237
238 /**
239 * Returns a string representation of the integer argument as an
240 * unsigned integer in base 16.
241 *
242 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
243 * if the argument is negative; otherwise, it is equal to the
244 * argument. This value is converted to a string of ASCII digits
245 * in hexadecimal (base 16) with no extra leading
246 * {@code 0}s.
247 *
248 * <p>The value of the argument can be recovered from the returned
249 * string {@code s} by calling {@link
250 * Integer#parseUnsignedInt(String, int)
251 * Integer.parseUnsignedInt(s, 16)}.
252 *
253 * <p>If the unsigned magnitude is zero, it is represented by a
254 * single zero character {@code '0'} ({@code '\u005Cu0030'});
255 * otherwise, the first character of the representation of the
256 * unsigned magnitude will not be the zero character. The
257 * following characters are used as hexadecimal digits:
258 *
259 * <blockquote>
260 * {@code 0123456789abcdef}
261 * </blockquote>
262 *
263 * These are the characters {@code '\u005Cu0030'} through
264 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
265 * {@code '\u005Cu0066'}. If uppercase letters are
266 * desired, the {@link java.lang.String#toUpperCase()} method may
267 * be called on the result:
268 *
269 * <blockquote>
270 * {@code Integer.toHexString(n).toUpperCase()}
271 * </blockquote>
272 *
273 * @apiNote
274 * The {@link java.util.HexFormat} class provides formatting and parsing
275 * of byte arrays and primitives to return a string or adding to an {@link Appendable}.
276 * {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
277 * with leading zeros and for byte arrays includes for each byte
278 * a delimiter, prefix, and suffix.
279 *
280 * @param i an integer to be converted to a string.
281 * @return the string representation of the unsigned integer value
282 * represented by the argument in hexadecimal (base 16).
283 * @see java.util.HexFormat
284 * @see #parseUnsignedInt(String, int)
285 * @see #toUnsignedString(int, int)
286 * @since 1.0.2
287 */
288 public static String toHexString(int i) {
289 return toUnsignedString0(i, 4);
290 }
291
292 /**
293 * Returns a string representation of the integer argument as an
294 * unsigned integer in base 8.
295 *
296 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
297 * if the argument is negative; otherwise, it is equal to the
298 * argument. This value is converted to a string of ASCII digits
299 * in octal (base 8) with no extra leading {@code 0}s.
300 *
301 * <p>The value of the argument can be recovered from the returned
302 * string {@code s} by calling {@link
303 * Integer#parseUnsignedInt(String, int)
304 * Integer.parseUnsignedInt(s, 8)}.
305 *
306 * <p>If the unsigned magnitude is zero, it is represented by a
307 * single zero character {@code '0'} ({@code '\u005Cu0030'});
308 * otherwise, the first character of the representation of the
309 * unsigned magnitude will not be the zero character. The
310 * following characters are used as octal digits:
311 *
312 * <blockquote>
313 * {@code 01234567}
314 * </blockquote>
315 *
316 * These are the characters {@code '\u005Cu0030'} through
317 * {@code '\u005Cu0037'}.
318 *
319 * @param i an integer to be converted to a string.
320 * @return the string representation of the unsigned integer value
321 * represented by the argument in octal (base 8).
322 * @see #parseUnsignedInt(String, int)
323 * @see #toUnsignedString(int, int)
324 * @since 1.0.2
325 */
326 public static String toOctalString(int i) {
327 return toUnsignedString0(i, 3);
328 }
329
330 /**
331 * Returns a string representation of the integer argument as an
332 * unsigned integer in base 2.
333 *
334 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
335 * if the argument is negative; otherwise it is equal to the
336 * argument. This value is converted to a string of ASCII digits
337 * in binary (base 2) with no extra leading {@code 0}s.
338 *
339 * <p>The value of the argument can be recovered from the returned
340 * string {@code s} by calling {@link
341 * Integer#parseUnsignedInt(String, int)
342 * Integer.parseUnsignedInt(s, 2)}.
343 *
344 * <p>If the unsigned magnitude is zero, it is represented by a
345 * single zero character {@code '0'} ({@code '\u005Cu0030'});
346 * otherwise, the first character of the representation of the
347 * unsigned magnitude will not be the zero character. The
348 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
349 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
350 *
351 * @param i an integer to be converted to a string.
352 * @return the string representation of the unsigned integer value
353 * represented by the argument in binary (base 2).
354 * @see #parseUnsignedInt(String, int)
355 * @see #toUnsignedString(int, int)
356 * @since 1.0.2
357 */
358 public static String toBinaryString(int i) {
359 return toUnsignedString0(i, 1);
360 }
361
362 /**
363 * Convert the integer to an unsigned number.
364 */
365 private static String toUnsignedString0(int val, int shift) {
366 // assert shift > 0 && shift <=5 : "Illegal shift value";
367 int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
368 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
369 if (COMPACT_STRINGS) {
370 byte[] buf = new byte[chars];
371 formatUnsignedInt(val, shift, buf, chars);
372 return new String(buf, LATIN1);
373 } else {
374 byte[] buf = new byte[chars * 2];
375 formatUnsignedIntUTF16(val, shift, buf, chars);
376 return new String(buf, UTF16);
377 }
378 }
379
380 /**
381 * Format an {@code int} (treated as unsigned) into a byte buffer (LATIN1 version). If
382 * {@code len} exceeds the formatted ASCII representation of {@code val},
383 * {@code buf} will be padded with leading zeroes.
384 *
385 * @param val the unsigned int to format
386 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
387 * @param buf the byte buffer to write to
388 * @param len the number of characters to write
389 */
390 private static void formatUnsignedInt(int val, int shift, byte[] buf, int len) {
391 int charPos = len;
392 int radix = 1 << shift;
393 int mask = radix - 1;
394 do {
395 buf[--charPos] = (byte)Integer.digits[val & mask];
396 val >>>= shift;
397 } while (charPos > 0);
398 }
399
400 /**
401 * Format an {@code int} (treated as unsigned) into a byte buffer (UTF16 version). If
402 * {@code len} exceeds the formatted ASCII representation of {@code val},
403 * {@code buf} will be padded with leading zeroes.
404 *
405 * @param val the unsigned int to format
406 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
407 * @param buf the byte buffer to write to
408 * @param len the number of characters to write
409 */
410 private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int len) {
411 int charPos = len;
412 int radix = 1 << shift;
413 int mask = radix - 1;
414 do {
415 StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
416 val >>>= shift;
417 } while (charPos > 0);
418 }
419
420 /**
421 * Returns a {@code String} object representing the
422 * specified integer. The argument is converted to signed decimal
423 * representation and returned as a string, exactly as if the
424 * argument and radix 10 were given as arguments to the {@link
425 * #toString(int, int)} method.
426 *
427 * @param i an integer to be converted.
428 * @return a string representation of the argument in base 10.
429 */
430 @IntrinsicCandidate
431 public static String toString(int i) {
432 int size = DecimalDigits.stringSize(i);
433 if (COMPACT_STRINGS) {
434 byte[] buf = new byte[size];
435 StringLatin1.getChars(i, size, buf);
436 return new String(buf, LATIN1);
437 } else {
438 byte[] buf = new byte[size * 2];
439 StringUTF16.getChars(i, size, buf);
440 return new String(buf, UTF16);
441 }
442 }
443
444 /**
445 * Returns a string representation of the argument as an unsigned
446 * decimal value.
447 *
448 * The argument is converted to unsigned decimal representation
449 * and returned as a string exactly as if the argument and radix
450 * 10 were given as arguments to the {@link #toUnsignedString(int,
451 * int)} method.
452 *
453 * @param i an integer to be converted to an unsigned string.
454 * @return an unsigned string representation of the argument.
455 * @see #toUnsignedString(int, int)
456 * @since 1.8
457 */
458 public static String toUnsignedString(int i) {
459 return Long.toString(toUnsignedLong(i));
460 }
461
462 /**
463 * Parses the string argument as a signed integer in the radix
464 * specified by the second argument. The characters in the string
465 * must all be digits of the specified radix (as determined by
466 * whether {@link java.lang.Character#digit(char, int)} returns a
467 * nonnegative value), except that the first character may be an
468 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
469 * indicate a negative value or an ASCII plus sign {@code '+'}
470 * ({@code '\u005Cu002B'}) to indicate a positive value. The
471 * resulting integer value is returned.
472 *
473 * <p>An exception of type {@code NumberFormatException} is
474 * thrown if any of the following situations occurs:
475 * <ul>
476 * <li>The first argument is {@code null} or is a string of
477 * length zero.
478 *
479 * <li>The radix is either smaller than
480 * {@link java.lang.Character#MIN_RADIX} or
481 * larger than {@link java.lang.Character#MAX_RADIX}.
482 *
483 * <li>Any character of the string is not a digit of the specified
484 * radix, except that the first character may be a minus sign
485 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign
486 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
487 * string is longer than length 1.
488 *
489 * <li>The value represented by the string is not a value of type
490 * {@code int}.
491 * </ul>
492 *
493 * <p>Examples:
494 * <blockquote><pre>
495 * parseInt("0", 10) returns 0
496 * parseInt("473", 10) returns 473
497 * parseInt("+42", 10) returns 42
498 * parseInt("-0", 10) returns 0
499 * parseInt("-FF", 16) returns -255
500 * parseInt("1100110", 2) returns 102
501 * parseInt("2147483647", 10) returns 2147483647
502 * parseInt("-2147483648", 10) returns -2147483648
503 * parseInt("2147483648", 10) throws a NumberFormatException
504 * parseInt("99", 8) throws a NumberFormatException
505 * parseInt("Kona", 10) throws a NumberFormatException
506 * parseInt("Kona", 27) returns 411787
507 * </pre></blockquote>
508 *
509 * @param s the {@code String} containing the integer
510 * representation to be parsed
511 * @param radix the radix to be used while parsing {@code s}.
512 * @return the integer represented by the string argument in the
513 * specified radix.
514 * @throws NumberFormatException if the {@code String}
515 * does not contain a parsable {@code int}.
516 */
517 public static int parseInt(String s, int radix)
518 throws NumberFormatException {
519 /*
520 * WARNING: This method may be invoked early during VM initialization
521 * before IntegerCache is initialized. Care must be taken to not use
522 * the valueOf method.
523 */
524
525 if (s == null) {
526 throw new NumberFormatException("Cannot parse null string");
527 }
528
529 if (radix < Character.MIN_RADIX) {
530 throw new NumberFormatException(String.format(
531 "radix %s less than Character.MIN_RADIX", radix));
532 }
533
534 if (radix > Character.MAX_RADIX) {
535 throw new NumberFormatException(String.format(
536 "radix %s greater than Character.MAX_RADIX", radix));
537 }
538
539 int len = s.length();
540 if (len == 0) {
541 throw NumberFormatException.forInputString("", radix);
542 }
543 int digit = ~0xFF;
544 int i = 0;
545 char firstChar = s.charAt(i++);
546 if (firstChar != '-' && firstChar != '+') {
547 digit = digit(firstChar, radix);
548 }
549 if (digit >= 0 || digit == ~0xFF && len > 1) {
550 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
551 int multmin = limit / radix;
552 int result = -(digit & 0xFF);
553 boolean inRange = true;
554 /* Accumulating negatively avoids surprises near MAX_VALUE */
555 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
556 && (inRange = result > multmin
557 || result == multmin && digit <= radix * multmin - limit)) {
558 result = radix * result - digit;
559 }
560 if (inRange && i == len && digit >= 0) {
561 return firstChar != '-' ? -result : result;
562 }
563 }
564 throw NumberFormatException.forInputString(s, radix);
565 }
566
567 /**
568 * Parses the {@link CharSequence} argument as a signed {@code int} in the
569 * specified {@code radix}, beginning at the specified {@code beginIndex}
570 * and extending to {@code endIndex - 1}.
571 *
572 * <p>The method does not take steps to guard against the
573 * {@code CharSequence} being mutated while parsing.
574 *
575 * @param s the {@code CharSequence} containing the {@code int}
576 * representation to be parsed
577 * @param beginIndex the beginning index, inclusive.
578 * @param endIndex the ending index, exclusive.
579 * @param radix the radix to be used while parsing {@code s}.
580 * @return the signed {@code int} represented by the subsequence in
581 * the specified radix.
582 * @throws NullPointerException if {@code s} is null.
583 * @throws IndexOutOfBoundsException if {@code beginIndex} is
584 * negative, or if {@code beginIndex} is greater than
585 * {@code endIndex} or if {@code endIndex} is greater than
586 * {@code s.length()}.
587 * @throws NumberFormatException if the {@code CharSequence} does not
588 * contain a parsable {@code int} in the specified
589 * {@code radix}, or if {@code radix} is either smaller than
590 * {@link java.lang.Character#MIN_RADIX} or larger than
591 * {@link java.lang.Character#MAX_RADIX}.
592 * @since 9
593 */
594 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
595 throws NumberFormatException {
596 Objects.requireNonNull(s);
597 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
598
599 if (radix < Character.MIN_RADIX) {
600 throw new NumberFormatException(String.format(
601 "radix %s less than Character.MIN_RADIX", radix));
602 }
603
604 if (radix > Character.MAX_RADIX) {
605 throw new NumberFormatException(String.format(
606 "radix %s greater than Character.MAX_RADIX", radix));
607 }
608
609 /*
610 * While s can be concurrently modified, it is ensured that each
611 * of its characters is read at most once, from lower to higher indices.
612 * This is obtained by reading them using the pattern s.charAt(i++),
613 * and by not updating i anywhere else.
614 */
615 if (beginIndex == endIndex) {
616 throw NumberFormatException.forInputString("", radix);
617 }
618 int digit = ~0xFF;
619 int i = beginIndex;
620 char firstChar = s.charAt(i++);
621 if (firstChar != '-' && firstChar != '+') {
622 digit = digit(firstChar, radix);
623 }
624 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
625 int limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
626 int multmin = limit / radix;
627 int result = -(digit & 0xFF);
628 boolean inRange = true;
629 /* Accumulating negatively avoids surprises near MAX_VALUE */
630 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
631 && (inRange = result > multmin
632 || result == multmin && digit <= radix * multmin - limit)) {
633 result = radix * result - digit;
634 }
635 if (inRange && i == endIndex && digit >= 0) {
636 return firstChar != '-' ? -result : result;
637 }
638 }
639 throw NumberFormatException.forCharSequence(s, beginIndex,
640 endIndex, i - (digit < -1 ? 0 : 1));
641 }
642
643 /**
644 * Parses the string argument as a signed decimal integer. The
645 * characters in the string must all be decimal digits, except
646 * that the first character may be an ASCII minus sign {@code '-'}
647 * ({@code '\u005Cu002D'}) to indicate a negative value or an
648 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
649 * indicate a positive value. The resulting integer value is
650 * returned, exactly as if the argument and the radix 10 were
651 * given as arguments to the {@link #parseInt(java.lang.String,
652 * int)} method.
653 *
654 * @param s a {@code String} containing the {@code int}
655 * representation to be parsed
656 * @return the integer value represented by the argument in decimal.
657 * @throws NumberFormatException if the string does not contain a
658 * parsable integer.
659 */
660 public static int parseInt(String s) throws NumberFormatException {
661 return parseInt(s, 10);
662 }
663
664 /**
665 * Parses the string argument as an unsigned integer in the radix
666 * specified by the second argument. An unsigned integer maps the
667 * values usually associated with negative numbers to positive
668 * numbers larger than {@code MAX_VALUE}.
669 *
670 * The characters in the string must all be digits of the
671 * specified radix (as determined by whether {@link
672 * java.lang.Character#digit(char, int)} returns a nonnegative
673 * value), except that the first character may be an ASCII plus
674 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
675 * integer value is returned.
676 *
677 * <p>An exception of type {@code NumberFormatException} is
678 * thrown if any of the following situations occurs:
679 * <ul>
680 * <li>The first argument is {@code null} or is a string of
681 * length zero.
682 *
683 * <li>The radix is either smaller than
684 * {@link java.lang.Character#MIN_RADIX} or
685 * larger than {@link java.lang.Character#MAX_RADIX}.
686 *
687 * <li>Any character of the string is not a digit of the specified
688 * radix, except that the first character may be a plus sign
689 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
690 * string is longer than length 1.
691 *
692 * <li>The value represented by the string is larger than the
693 * largest unsigned {@code int}, 2<sup>32</sup>-1.
694 *
695 * </ul>
696 *
697 *
698 * @param s the {@code String} containing the unsigned integer
699 * representation to be parsed
700 * @param radix the radix to be used while parsing {@code s}.
701 * @return the integer represented by the string argument in the
702 * specified radix.
703 * @throws NumberFormatException if the {@code String}
704 * does not contain a parsable {@code int}.
705 * @since 1.8
706 */
707 public static int parseUnsignedInt(String s, int radix)
708 throws NumberFormatException {
709 if (s == null) {
710 throw new NumberFormatException("Cannot parse null string");
711 }
712
713 if (radix < Character.MIN_RADIX) {
714 throw new NumberFormatException(String.format(
715 "radix %s less than Character.MIN_RADIX", radix));
716 }
717
718 if (radix > Character.MAX_RADIX) {
719 throw new NumberFormatException(String.format(
720 "radix %s greater than Character.MAX_RADIX", radix));
721 }
722
723 int len = s.length();
724 if (len == 0) {
725 throw NumberFormatException.forInputString(s, radix);
726 }
727 int i = 0;
728 char firstChar = s.charAt(i++);
729 if (firstChar == '-') {
730 throw new NumberFormatException(String.format(
731 "Illegal leading minus sign on unsigned string %s.", s));
732 }
733 int digit = ~0xFF;
734 if (firstChar != '+') {
735 digit = digit(firstChar, radix);
736 }
737 if (digit >= 0 || digit == ~0xFF && len > 1) {
738 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
739 int result = digit & 0xFF;
740 boolean inRange = true;
741 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
742 && (inRange = compareUnsigned(result, multmax) < 0
743 || result == multmax && digit < -radix * multmax)) {
744 result = radix * result + digit;
745 }
746 if (inRange && i == len && digit >= 0) {
747 return result;
748 }
749 }
750 if (digit < 0) {
751 throw NumberFormatException.forInputString(s, radix);
752 }
753 throw new NumberFormatException(String.format(
754 "String value %s exceeds range of unsigned int.", s));
755 }
756
757 /**
758 * Parses the {@link CharSequence} argument as an unsigned {@code int} in
759 * the specified {@code radix}, beginning at the specified
760 * {@code beginIndex} and extending to {@code endIndex - 1}.
761 *
762 * <p>The method does not take steps to guard against the
763 * {@code CharSequence} being mutated while parsing.
764 *
765 * @param s the {@code CharSequence} containing the unsigned
766 * {@code int} representation to be parsed
767 * @param beginIndex the beginning index, inclusive.
768 * @param endIndex the ending index, exclusive.
769 * @param radix the radix to be used while parsing {@code s}.
770 * @return the unsigned {@code int} represented by the subsequence in
771 * the specified radix.
772 * @throws NullPointerException if {@code s} is null.
773 * @throws IndexOutOfBoundsException if {@code beginIndex} is
774 * negative, or if {@code beginIndex} is greater than
775 * {@code endIndex} or if {@code endIndex} is greater than
776 * {@code s.length()}.
777 * @throws NumberFormatException if the {@code CharSequence} does not
778 * contain a parsable unsigned {@code int} in the specified
779 * {@code radix}, or if {@code radix} is either smaller than
780 * {@link java.lang.Character#MIN_RADIX} or larger than
781 * {@link java.lang.Character#MAX_RADIX}.
782 * @since 9
783 */
784 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
785 throws NumberFormatException {
786 Objects.requireNonNull(s);
787 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
788
789 if (radix < Character.MIN_RADIX) {
790 throw new NumberFormatException(String.format(
791 "radix %s less than Character.MIN_RADIX", radix));
792 }
793
794 if (radix > Character.MAX_RADIX) {
795 throw new NumberFormatException(String.format(
796 "radix %s greater than Character.MAX_RADIX", radix));
797 }
798
799 /*
800 * While s can be concurrently modified, it is ensured that each
801 * of its characters is read at most once, from lower to higher indices.
802 * This is obtained by reading them using the pattern s.charAt(i++),
803 * and by not updating i anywhere else.
804 */
805 if (beginIndex == endIndex) {
806 throw NumberFormatException.forInputString("", radix);
807 }
808 int i = beginIndex;
809 char firstChar = s.charAt(i++);
810 if (firstChar == '-') {
811 throw new NumberFormatException(
812 "Illegal leading minus sign on unsigned string " + s + ".");
813 }
814 int digit = ~0xFF;
815 if (firstChar != '+') {
816 digit = digit(firstChar, radix);
817 }
818 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
819 int multmax = divideUnsigned(-1, radix); // -1 is max unsigned int
820 int result = digit & 0xFF;
821 boolean inRange = true;
822 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
823 && (inRange = compareUnsigned(result, multmax) < 0
824 || result == multmax && digit < -radix * multmax)) {
825 result = radix * result + digit;
826 }
827 if (inRange && i == endIndex && digit >= 0) {
828 return result;
829 }
830 }
831 if (digit < 0) {
832 throw NumberFormatException.forCharSequence(s, beginIndex,
833 endIndex, i - (digit < -1 ? 0 : 1));
834 }
835 throw new NumberFormatException(String.format(
836 "String value %s exceeds range of unsigned int.", s));
837 }
838
839 /**
840 * Parses the string argument as an unsigned decimal integer. The
841 * characters in the string must all be decimal digits, except
842 * that the first character may be an ASCII plus sign {@code
843 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
844 * is returned, exactly as if the argument and the radix 10 were
845 * given as arguments to the {@link
846 * #parseUnsignedInt(java.lang.String, int)} method.
847 *
848 * @param s a {@code String} containing the unsigned {@code int}
849 * representation to be parsed
850 * @return the unsigned integer value represented by the argument in decimal.
851 * @throws NumberFormatException if the string does not contain a
852 * parsable unsigned integer.
853 * @since 1.8
854 */
855 public static int parseUnsignedInt(String s) throws NumberFormatException {
856 return parseUnsignedInt(s, 10);
857 }
858
859 /**
860 * Returns an {@code Integer} object holding the value
861 * extracted from the specified {@code String} when parsed
862 * with the radix given by the second argument. The first argument
863 * is interpreted as representing a signed integer in the radix
864 * specified by the second argument, exactly as if the arguments
865 * were given to the {@link #parseInt(java.lang.String, int)}
866 * method. The result is an {@code Integer} object that
867 * represents the integer value specified by the string.
868 *
869 * <p>In other words, this method returns an {@code Integer}
870 * object equal to the value of:
871 *
872 * <blockquote>
873 * {@code Integer.valueOf(Integer.parseInt(s, radix))}
874 * </blockquote>
875 *
876 * @param s the string to be parsed.
877 * @param radix the radix to be used in interpreting {@code s}
878 * @return an {@code Integer} object holding the value
879 * represented by the string argument in the specified
880 * radix.
881 * @throws NumberFormatException if the {@code String}
882 * does not contain a parsable {@code int}.
883 */
884 public static Integer valueOf(String s, int radix) throws NumberFormatException {
885 return Integer.valueOf(parseInt(s,radix));
886 }
887
888 /**
889 * Returns an {@code Integer} object holding the
890 * value of the specified {@code String}. The argument is
891 * interpreted as representing a signed decimal integer, exactly
892 * as if the argument were given to the {@link
893 * #parseInt(java.lang.String)} method. The result is an
894 * {@code Integer} object that represents the integer value
895 * specified by the string.
896 *
897 * <p>In other words, this method returns an {@code Integer}
898 * object equal to the value of:
899 *
900 * <blockquote>
901 * {@code Integer.valueOf(Integer.parseInt(s))}
902 * </blockquote>
903 *
904 * @param s the string to be parsed.
905 * @return an {@code Integer} object holding the value
906 * represented by the string argument.
907 * @throws NumberFormatException if the string cannot be parsed
908 * as an integer.
909 */
910 public static Integer valueOf(String s) throws NumberFormatException {
911 return Integer.valueOf(parseInt(s, 10));
912 }
913
914 /**
915 * Cache to support the object identity semantics of autoboxing for values between
916 * -128 and 127 (inclusive) as required by JLS.
917 *
918 * The cache is initialized on first usage. The size of the cache
919 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
920 * During VM initialization, java.lang.Integer.IntegerCache.high property
921 * may be set and saved in the private system properties in the
922 * jdk.internal.misc.VM class.
923 *
924 * WARNING: The cache is archived with CDS and reloaded from the shared
925 * archive at runtime. The archived cache (Integer[]) and Integer objects
926 * reside in the closed archive heap regions. Care should be taken when
927 * changing the implementation and the cache array should not be assigned
928 * with new Integer object(s) after initialization.
929 */
930
931 private static final class IntegerCache {
932 static final int low = -128;
933 static final int high;
934
935 @Stable
936 static final Integer[] cache;
937 static Integer[] archivedCache;
938
939 static {
940 // high value may be configured by property
941 int h = 127;
942 String integerCacheHighPropValue =
943 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
944 if (integerCacheHighPropValue != null) {
945 try {
946 h = Math.max(parseInt(integerCacheHighPropValue), 127);
947 // Maximum array size is Integer.MAX_VALUE
948 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
949 } catch( NumberFormatException nfe) {
950 // If the property cannot be parsed into an int, ignore it.
951 }
952 }
953 high = h;
954
955 // Load IntegerCache.archivedCache from archive, if possible
956 CDS.initializeFromArchive(IntegerCache.class);
957 int size = (high - low) + 1;
958
959 // Use the archived cache if it exists and is large enough
960 if (archivedCache == null || size > archivedCache.length) {
961 Integer[] c = new Integer[size];
962 int j = low;
963 // If archive has Integer cache, we must use all instances from it.
964 // Otherwise, the identity checks between archived Integers and
965 // runtime-cached Integers would fail.
966 int archivedSize = (archivedCache == null) ? 0 : archivedCache.length;
967 for (int i = 0; i < archivedSize; i++) {
968 c[i] = archivedCache[i];
969 assert j == archivedCache[i];
970 j++;
971 }
972 // Fill the rest of the cache.
973 for (int i = archivedSize; i < size; i++) {
974 c[i] = new Integer(j++);
975 }
976 archivedCache = c;
977 }
978 cache = archivedCache;
979 // range [-128, 127] must be interned (JLS7 5.1.7)
980 assert IntegerCache.high >= 127;
981 }
982
983 private IntegerCache() {}
984 }
985
986 /**
987 * Returns an {@code Integer} instance representing the specified
988 * {@code int} value. If a new {@code Integer} instance is not
989 * required, this method should generally be used in preference to
990 * the constructor {@link #Integer(int)}, as this method is likely
991 * to yield significantly better space and time performance by
992 * caching frequently requested values.
993 *
994 * This method will always cache values in the range -128 to 127,
995 * inclusive, and may cache other values outside of this range.
996 *
997 * @param i an {@code int} value.
998 * @return an {@code Integer} instance representing {@code i}.
999 * @since 1.5
1000 */
1001 @IntrinsicCandidate
1002 public static Integer valueOf(int i) {
1003 if (i >= IntegerCache.low && i <= IntegerCache.high)
1004 return IntegerCache.cache[i + (-IntegerCache.low)];
1005 return new Integer(i);
1006 }
1007
1008 /**
1009 * The value of the {@code Integer}.
1010 *
1011 * @serial
1012 */
1013 private final int value;
1014
1015 /**
1016 * Constructs a newly allocated {@code Integer} object that
1017 * represents the specified {@code int} value.
1018 *
1019 * @param value the value to be represented by the
1020 * {@code Integer} object.
1021 *
1022 * @deprecated
1023 * It is rarely appropriate to use this constructor. The static factory
1024 * {@link #valueOf(int)} is generally a better choice, as it is
1025 * likely to yield significantly better space and time performance.
1026 */
1027 @Deprecated(since="9", forRemoval = true)
1028 public Integer(int value) {
1029 this.value = value;
1030 }
1031
1032 /**
1033 * Constructs a newly allocated {@code Integer} object that
1034 * represents the {@code int} value indicated by the
1035 * {@code String} parameter. The string is converted to an
1036 * {@code int} value in exactly the manner used by the
1037 * {@code parseInt} method for radix 10.
1038 *
1039 * @param s the {@code String} to be converted to an {@code Integer}.
1040 * @throws NumberFormatException if the {@code String} does not
1041 * contain a parsable integer.
1042 *
1043 * @deprecated
1044 * It is rarely appropriate to use this constructor.
1045 * Use {@link #parseInt(String)} to convert a string to a
1046 * {@code int} primitive, or use {@link #valueOf(String)}
1047 * to convert a string to an {@code Integer} object.
1048 */
1049 @Deprecated(since="9", forRemoval = true)
1050 public Integer(String s) throws NumberFormatException {
1051 this.value = parseInt(s, 10);
1052 }
1053
1054 /**
1055 * Returns the value of this {@code Integer} as a {@code byte}
1056 * after a narrowing primitive conversion.
1057 * @jls 5.1.3 Narrowing Primitive Conversion
1058 */
1059 public byte byteValue() {
1060 return (byte)value;
1061 }
1062
1063 /**
1064 * Returns the value of this {@code Integer} as a {@code short}
1065 * after a narrowing primitive conversion.
1066 * @jls 5.1.3 Narrowing Primitive Conversion
1067 */
1068 public short shortValue() {
1069 return (short)value;
1070 }
1071
1072 /**
1073 * Returns the value of this {@code Integer} as an
1074 * {@code int}.
1075 */
1076 @IntrinsicCandidate
1077 public int intValue() {
1078 return value;
1079 }
1080
1081 /**
1082 * Returns the value of this {@code Integer} as a {@code long}
1083 * after a widening primitive conversion.
1084 * @jls 5.1.2 Widening Primitive Conversion
1085 * @see Integer#toUnsignedLong(int)
1086 */
1087 public long longValue() {
1088 return (long)value;
1089 }
1090
1091 /**
1092 * Returns the value of this {@code Integer} as a {@code float}
1093 * after a widening primitive conversion.
1094 * @jls 5.1.2 Widening Primitive Conversion
1095 */
1096 public float floatValue() {
1097 return (float)value;
1098 }
1099
1100 /**
1101 * Returns the value of this {@code Integer} as a {@code double}
1102 * after a widening primitive conversion.
1103 * @jls 5.1.2 Widening Primitive Conversion
1104 */
1105 public double doubleValue() {
1106 return (double)value;
1107 }
1108
1109 /**
1110 * Returns a {@code String} object representing this
1111 * {@code Integer}'s value. The value is converted to signed
1112 * decimal representation and returned as a string, exactly as if
1113 * the integer value were given as an argument to the {@link
1114 * java.lang.Integer#toString(int)} method.
1115 *
1116 * @return a string representation of the value of this object in
1117 * base 10.
1118 */
1119 public String toString() {
1120 return toString(value);
1121 }
1122
1123 /**
1124 * Returns a hash code for this {@code Integer}.
1125 *
1126 * @return a hash code value for this object, equal to the
1127 * primitive {@code int} value represented by this
1128 * {@code Integer} object.
1129 */
1130 @Override
1131 public int hashCode() {
1132 return Integer.hashCode(value);
1133 }
1134
1135 /**
1136 * Returns a hash code for an {@code int} value; compatible with
1137 * {@code Integer.hashCode()}.
1138 *
1139 * @param value the value to hash
1140 * @since 1.8
1141 *
1142 * @return a hash code value for an {@code int} value.
1143 */
1144 public static int hashCode(int value) {
1145 return value;
1146 }
1147
1148 /**
1149 * Compares this object to the specified object. The result is
1150 * {@code true} if and only if the argument is not
1151 * {@code null} and is an {@code Integer} object that
1152 * contains the same {@code int} value as this object.
1153 *
1154 * @param obj the object to compare with.
1155 * @return {@code true} if the objects are the same;
1156 * {@code false} otherwise.
1157 */
1158 public boolean equals(Object obj) {
1159 if (obj instanceof Integer i) {
1160 return value == i.intValue();
1161 }
1162 return false;
1163 }
1164
1165 /**
1166 * Determines the integer value of the system property with the
1167 * specified name.
1168 *
1169 * <p>The first argument is treated as the name of a system
1170 * property. System properties are accessible through the {@link
1171 * java.lang.System#getProperty(java.lang.String)} method. The
1172 * string value of this property is then interpreted as an integer
1173 * value using the grammar supported by {@link Integer#decode decode} and
1174 * an {@code Integer} object representing this value is returned.
1175 *
1176 * <p>If there is no property with the specified name, if the
1177 * specified name is empty or {@code null}, or if the property
1178 * does not have the correct numeric format, then {@code null} is
1179 * returned.
1180 *
1181 * <p>In other words, this method returns an {@code Integer}
1182 * object equal to the value of:
1183 *
1184 * <blockquote>
1185 * {@code getInteger(nm, null)}
1186 * </blockquote>
1187 *
1188 * @param nm property name.
1189 * @return the {@code Integer} value of the property.
1190 * @throws SecurityException for the same reasons as
1191 * {@link System#getProperty(String) System.getProperty}
1192 * @see java.lang.System#getProperty(java.lang.String)
1193 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1194 */
1195 public static Integer getInteger(String nm) {
1196 return getInteger(nm, null);
1197 }
1198
1199 /**
1200 * Determines the integer value of the system property with the
1201 * specified name.
1202 *
1203 * <p>The first argument is treated as the name of a system
1204 * property. System properties are accessible through the {@link
1205 * java.lang.System#getProperty(java.lang.String)} method. The
1206 * string value of this property is then interpreted as an integer
1207 * value using the grammar supported by {@link Integer#decode decode} and
1208 * an {@code Integer} object representing this value is returned.
1209 *
1210 * <p>The second argument is the default value. An {@code Integer} object
1211 * that represents the value of the second argument is returned if there
1212 * is no property of the specified name, if the property does not have
1213 * the correct numeric format, or if the specified name is empty or
1214 * {@code null}.
1215 *
1216 * <p>In other words, this method returns an {@code Integer} object
1217 * equal to the value of:
1218 *
1219 * <blockquote>
1220 * {@code getInteger(nm, Integer.valueOf(val))}
1221 * </blockquote>
1222 *
1223 * but in practice it may be implemented in a manner such as:
1224 *
1225 * <blockquote><pre>
1226 * Integer result = getInteger(nm, null);
1227 * return (result == null) ? Integer.valueOf(val) : result;
1228 * </pre></blockquote>
1229 *
1230 * to avoid the unnecessary allocation of an {@code Integer}
1231 * object when the default value is not needed.
1232 *
1233 * @param nm property name.
1234 * @param val default value.
1235 * @return the {@code Integer} value of the property.
1236 * @throws SecurityException for the same reasons as
1237 * {@link System#getProperty(String) System.getProperty}
1238 * @see java.lang.System#getProperty(java.lang.String)
1239 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1240 */
1241 public static Integer getInteger(String nm, int val) {
1242 Integer result = getInteger(nm, null);
1243 return (result == null) ? Integer.valueOf(val) : result;
1244 }
1245
1246 /**
1247 * Returns the integer value of the system property with the
1248 * specified name. The first argument is treated as the name of a
1249 * system property. System properties are accessible through the
1250 * {@link java.lang.System#getProperty(java.lang.String)} method.
1251 * The string value of this property is then interpreted as an
1252 * integer value, as per the {@link Integer#decode decode} method,
1253 * and an {@code Integer} object representing this value is
1254 * returned; in summary:
1255 *
1256 * <ul><li>If the property value begins with the two ASCII characters
1257 * {@code 0x} or the ASCII character {@code #}, not
1258 * followed by a minus sign, then the rest of it is parsed as a
1259 * hexadecimal integer exactly as by the method
1260 * {@link #valueOf(java.lang.String, int)} with radix 16.
1261 * <li>If the property value begins with the ASCII character
1262 * {@code 0} followed by another character, it is parsed as an
1263 * octal integer exactly as by the method
1264 * {@link #valueOf(java.lang.String, int)} with radix 8.
1265 * <li>Otherwise, the property value is parsed as a decimal integer
1266 * exactly as by the method {@link #valueOf(java.lang.String, int)}
1267 * with radix 10.
1268 * </ul>
1269 *
1270 * <p>The second argument is the default value. The default value is
1271 * returned if there is no property of the specified name, if the
1272 * property does not have the correct numeric format, or if the
1273 * specified name is empty or {@code null}.
1274 *
1275 * @param nm property name.
1276 * @param val default value.
1277 * @return the {@code Integer} value of the property.
1278 * @throws SecurityException for the same reasons as
1279 * {@link System#getProperty(String) System.getProperty}
1280 * @see System#getProperty(java.lang.String)
1281 * @see System#getProperty(java.lang.String, java.lang.String)
1282 */
1283 public static Integer getInteger(String nm, Integer val) {
1284 String v = null;
1285 try {
1286 v = System.getProperty(nm);
1287 } catch (IllegalArgumentException | NullPointerException e) {
1288 }
1289 if (v != null) {
1290 try {
1291 return Integer.decode(v);
1292 } catch (NumberFormatException e) {
1293 }
1294 }
1295 return val;
1296 }
1297
1298 /**
1299 * Decodes a {@code String} into an {@code Integer}.
1300 * Accepts decimal, hexadecimal, and octal numbers given
1301 * by the following grammar:
1302 *
1303 * <blockquote>
1304 * <dl>
1305 * <dt><i>DecodableString:</i>
1306 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1307 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1308 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1309 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1310 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1311 *
1312 * <dt><i>Sign:</i>
1313 * <dd>{@code -}
1314 * <dd>{@code +}
1315 * </dl>
1316 * </blockquote>
1317 *
1318 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1319 * are as defined in section {@jls 3.10.1} of
1320 * <cite>The Java Language Specification</cite>,
1321 * except that underscores are not accepted between digits.
1322 *
1323 * <p>The sequence of characters following an optional
1324 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1325 * "{@code #}", or leading zero) is parsed as by the {@code
1326 * Integer.parseInt} method with the indicated radix (10, 16, or
1327 * 8). This sequence of characters must represent a positive
1328 * value or a {@link NumberFormatException} will be thrown. The
1329 * result is negated if first character of the specified {@code
1330 * String} is the minus sign. No whitespace characters are
1331 * permitted in the {@code String}.
1332 *
1333 * @param nm the {@code String} to decode.
1334 * @return an {@code Integer} object holding the {@code int}
1335 * value represented by {@code nm}
1336 * @throws NumberFormatException if the {@code String} does not
1337 * contain a parsable integer.
1338 * @see java.lang.Integer#parseInt(java.lang.String, int)
1339 */
1340 public static Integer decode(String nm) throws NumberFormatException {
1341 int radix = 10;
1342 int index = 0;
1343 boolean negative = false;
1344 int result;
1345
1346 if (nm.isEmpty())
1347 throw new NumberFormatException("Zero length string");
1348 char firstChar = nm.charAt(0);
1349 // Handle sign, if present
1350 if (firstChar == '-') {
1351 negative = true;
1352 index++;
1353 } else if (firstChar == '+')
1354 index++;
1355
1356 // Handle radix specifier, if present
1357 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1358 index += 2;
1359 radix = 16;
1360 }
1361 else if (nm.startsWith("#", index)) {
1362 index ++;
1363 radix = 16;
1364 }
1365 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1366 index ++;
1367 radix = 8;
1368 }
1369
1370 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1371 throw new NumberFormatException("Sign character in wrong position");
1372
1373 try {
1374 result = parseInt(nm, index, nm.length(), radix);
1375 result = negative ? -result : result;
1376 } catch (NumberFormatException e) {
1377 // If number is Integer.MIN_VALUE, we'll end up here. The next line
1378 // handles this case, and causes any genuine format error to be
1379 // rethrown.
1380 String constant = negative ? ("-" + nm.substring(index))
1381 : nm.substring(index);
1382 result = parseInt(constant, radix);
1383 }
1384 return result;
1385 }
1386
1387 /**
1388 * Compares two {@code Integer} objects numerically.
1389 *
1390 * @param anotherInteger the {@code Integer} to be compared.
1391 * @return the value {@code 0} if this {@code Integer} is
1392 * equal to the argument {@code Integer}; a value less than
1393 * {@code 0} if this {@code Integer} is numerically less
1394 * than the argument {@code Integer}; and a value greater
1395 * than {@code 0} if this {@code Integer} is numerically
1396 * greater than the argument {@code Integer} (signed
1397 * comparison).
1398 * @since 1.2
1399 */
1400 public int compareTo(Integer anotherInteger) {
1401 return compare(this.value, anotherInteger.value);
1402 }
1403
1404 /**
1405 * Compares two {@code int} values numerically.
1406 * The value returned is identical to what would be returned by:
1407 * <pre>
1408 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1409 * </pre>
1410 *
1411 * @param x the first {@code int} to compare
1412 * @param y the second {@code int} to compare
1413 * @return the value {@code 0} if {@code x == y};
1414 * a value less than {@code 0} if {@code x < y}; and
1415 * a value greater than {@code 0} if {@code x > y}
1416 * @since 1.7
1417 */
1418 public static int compare(int x, int y) {
1419 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1420 }
1421
1422 /**
1423 * Compares two {@code int} values numerically treating the values
1424 * as unsigned.
1425 *
1426 * @param x the first {@code int} to compare
1427 * @param y the second {@code int} to compare
1428 * @return the value {@code 0} if {@code x == y}; a value less
1429 * than {@code 0} if {@code x < y} as unsigned values; and
1430 * a value greater than {@code 0} if {@code x > y} as
1431 * unsigned values
1432 * @since 1.8
1433 */
1434 @IntrinsicCandidate
1435 public static int compareUnsigned(int x, int y) {
1436 return compare(x + MIN_VALUE, y + MIN_VALUE);
1437 }
1438
1439 /**
1440 * Converts the argument to a {@code long} by an unsigned
1441 * conversion. In an unsigned conversion to a {@code long}, the
1442 * high-order 32 bits of the {@code long} are zero and the
1443 * low-order 32 bits are equal to the bits of the integer
1444 * argument.
1445 *
1446 * Consequently, zero and positive {@code int} values are mapped
1447 * to a numerically equal {@code long} value and negative {@code
1448 * int} values are mapped to a {@code long} value equal to the
1449 * input plus 2<sup>32</sup>.
1450 *
1451 * @param x the value to convert to an unsigned {@code long}
1452 * @return the argument converted to {@code long} by an unsigned
1453 * conversion
1454 * @since 1.8
1455 */
1456 public static long toUnsignedLong(int x) {
1457 return ((long) x) & 0xffffffffL;
1458 }
1459
1460 /**
1461 * Returns the unsigned quotient of dividing the first argument by
1462 * the second where each argument and the result is interpreted as
1463 * an unsigned value.
1464 *
1465 * <p>Note that in two's complement arithmetic, the three other
1466 * basic arithmetic operations of add, subtract, and multiply are
1467 * bit-wise identical if the two operands are regarded as both
1468 * being signed or both being unsigned. Therefore separate {@code
1469 * addUnsigned}, etc. methods are not provided.
1470 *
1471 * @param dividend the value to be divided
1472 * @param divisor the value doing the dividing
1473 * @return the unsigned quotient of the first argument divided by
1474 * the second argument
1475 * @see #remainderUnsigned
1476 * @since 1.8
1477 */
1478 @IntrinsicCandidate
1479 public static int divideUnsigned(int dividend, int divisor) {
1480 // In lieu of tricky code, for now just use long arithmetic.
1481 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor));
1482 }
1483
1484 /**
1485 * Returns the unsigned remainder from dividing the first argument
1486 * by the second where each argument and the result is interpreted
1487 * as an unsigned value.
1488 *
1489 * @param dividend the value to be divided
1490 * @param divisor the value doing the dividing
1491 * @return the unsigned remainder of the first argument divided by
1492 * the second argument
1493 * @see #divideUnsigned
1494 * @since 1.8
1495 */
1496 @IntrinsicCandidate
1497 public static int remainderUnsigned(int dividend, int divisor) {
1498 // In lieu of tricky code, for now just use long arithmetic.
1499 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor));
1500 }
1501
1502
1503 // Bit twiddling
1504
1505 /**
1506 * The number of bits used to represent an {@code int} value in two's
1507 * complement binary form.
1508 *
1509 * @since 1.5
1510 */
1511 @Native public static final int SIZE = 32;
1512
1513 /**
1514 * The number of bytes used to represent an {@code int} value in two's
1515 * complement binary form.
1516 *
1517 * @since 1.8
1518 */
1519 public static final int BYTES = SIZE / Byte.SIZE;
1520
1521 /**
1522 * Returns an {@code int} value with at most a single one-bit, in the
1523 * position of the highest-order ("leftmost") one-bit in the specified
1524 * {@code int} value. Returns zero if the specified value has no
1525 * one-bits in its two's complement binary representation, that is, if it
1526 * is equal to zero.
1527 *
1528 * @param i the value whose highest one bit is to be computed
1529 * @return an {@code int} value with a single one-bit, in the position
1530 * of the highest-order one-bit in the specified value, or zero if
1531 * the specified value is itself equal to zero.
1532 * @since 1.5
1533 */
1534 public static int highestOneBit(int i) {
1535 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1536 }
1537
1538 /**
1539 * Returns an {@code int} value with at most a single one-bit, in the
1540 * position of the lowest-order ("rightmost") one-bit in the specified
1541 * {@code int} value. Returns zero if the specified value has no
1542 * one-bits in its two's complement binary representation, that is, if it
1543 * is equal to zero.
1544 *
1545 * @param i the value whose lowest one bit is to be computed
1546 * @return an {@code int} value with a single one-bit, in the position
1547 * of the lowest-order one-bit in the specified value, or zero if
1548 * the specified value is itself equal to zero.
1549 * @since 1.5
1550 */
1551 public static int lowestOneBit(int i) {
1552 // HD, Section 2-1
1553 return i & -i;
1554 }
1555
1556 /**
1557 * Returns the number of zero bits preceding the highest-order
1558 * ("leftmost") one-bit in the two's complement binary representation
1559 * of the specified {@code int} value. Returns 32 if the
1560 * specified value has no one-bits in its two's complement representation,
1561 * in other words if it is equal to zero.
1562 *
1563 * <p>Note that this method is closely related to the logarithm base 2.
1564 * For all positive {@code int} values x:
1565 * <ul>
1566 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1567 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1568 * </ul>
1569 *
1570 * @param i the value whose number of leading zeros is to be computed
1571 * @return the number of zero bits preceding the highest-order
1572 * ("leftmost") one-bit in the two's complement binary representation
1573 * of the specified {@code int} value, or 32 if the value
1574 * is equal to zero.
1575 * @since 1.5
1576 */
1577 @IntrinsicCandidate
1578 public static int numberOfLeadingZeros(int i) {
1579 // HD, Count leading 0's
1580 if (i <= 0)
1581 return i == 0 ? 32 : 0;
1582 int n = 31;
1583 if (i >= 1 << 16) { n -= 16; i >>>= 16; }
1584 if (i >= 1 << 8) { n -= 8; i >>>= 8; }
1585 if (i >= 1 << 4) { n -= 4; i >>>= 4; }
1586 if (i >= 1 << 2) { n -= 2; i >>>= 2; }
1587 return n - (i >>> 1);
1588 }
1589
1590 /**
1591 * Returns the number of zero bits following the lowest-order ("rightmost")
1592 * one-bit in the two's complement binary representation of the specified
1593 * {@code int} value. Returns 32 if the specified value has no
1594 * one-bits in its two's complement representation, in other words if it is
1595 * equal to zero.
1596 *
1597 * @param i the value whose number of trailing zeros is to be computed
1598 * @return the number of zero bits following the lowest-order ("rightmost")
1599 * one-bit in the two's complement binary representation of the
1600 * specified {@code int} value, or 32 if the value is equal
1601 * to zero.
1602 * @since 1.5
1603 */
1604 @IntrinsicCandidate
1605 public static int numberOfTrailingZeros(int i) {
1606 // HD, Count trailing 0's
1607 i = ~i & (i - 1);
1608 if (i <= 0) return i & 32;
1609 int n = 1;
1610 if (i > 1 << 16) { n += 16; i >>>= 16; }
1611 if (i > 1 << 8) { n += 8; i >>>= 8; }
1612 if (i > 1 << 4) { n += 4; i >>>= 4; }
1613 if (i > 1 << 2) { n += 2; i >>>= 2; }
1614 return n + (i >>> 1);
1615 }
1616
1617 /**
1618 * Returns the number of one-bits in the two's complement binary
1619 * representation of the specified {@code int} value. This function is
1620 * sometimes referred to as the <i>population count</i>.
1621 *
1622 * @param i the value whose bits are to be counted
1623 * @return the number of one-bits in the two's complement binary
1624 * representation of the specified {@code int} value.
1625 * @since 1.5
1626 */
1627 @IntrinsicCandidate
1628 public static int bitCount(int i) {
1629 // HD, Figure 5-2
1630 i = i - ((i >>> 1) & 0x55555555);
1631 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1632 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1633 i = i + (i >>> 8);
1634 i = i + (i >>> 16);
1635 return i & 0x3f;
1636 }
1637
1638 /**
1639 * Returns the value obtained by rotating the two's complement binary
1640 * representation of the specified {@code int} value left by the
1641 * specified number of bits. (Bits shifted out of the left hand, or
1642 * high-order, side reenter on the right, or low-order.)
1643 *
1644 * <p>Note that left rotation with a negative distance is equivalent to
1645 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1646 * distance)}. Note also that rotation by any multiple of 32 is a
1647 * no-op, so all but the last five bits of the rotation distance can be
1648 * ignored, even if the distance is negative: {@code rotateLeft(val,
1649 * distance) == rotateLeft(val, distance & 0x1F)}.
1650 *
1651 * @param i the value whose bits are to be rotated left
1652 * @param distance the number of bit positions to rotate left
1653 * @return the value obtained by rotating the two's complement binary
1654 * representation of the specified {@code int} value left by the
1655 * specified number of bits.
1656 * @since 1.5
1657 */
1658 public static int rotateLeft(int i, int distance) {
1659 return (i << distance) | (i >>> -distance);
1660 }
1661
1662 /**
1663 * Returns the value obtained by rotating the two's complement binary
1664 * representation of the specified {@code int} value right by the
1665 * specified number of bits. (Bits shifted out of the right hand, or
1666 * low-order, side reenter on the left, or high-order.)
1667 *
1668 * <p>Note that right rotation with a negative distance is equivalent to
1669 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1670 * distance)}. Note also that rotation by any multiple of 32 is a
1671 * no-op, so all but the last five bits of the rotation distance can be
1672 * ignored, even if the distance is negative: {@code rotateRight(val,
1673 * distance) == rotateRight(val, distance & 0x1F)}.
1674 *
1675 * @param i the value whose bits are to be rotated right
1676 * @param distance the number of bit positions to rotate right
1677 * @return the value obtained by rotating the two's complement binary
1678 * representation of the specified {@code int} value right by the
1679 * specified number of bits.
1680 * @since 1.5
1681 */
1682 public static int rotateRight(int i, int distance) {
1683 return (i >>> distance) | (i << -distance);
1684 }
1685
1686 /**
1687 * Returns the value obtained by reversing the order of the bits in the
1688 * two's complement binary representation of the specified {@code int}
1689 * value.
1690 *
1691 * @param i the value to be reversed
1692 * @return the value obtained by reversing order of the bits in the
1693 * specified {@code int} value.
1694 * @since 1.5
1695 */
1696 @IntrinsicCandidate
1697 public static int reverse(int i) {
1698 // HD, Figure 7-1
1699 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1700 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1701 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1702
1703 return reverseBytes(i);
1704 }
1705
1706 /**
1707 * Returns the value obtained by compressing the bits of the
1708 * specified {@code int} value, {@code i}, in accordance with
1709 * the specified bit mask.
1710 * <p>
1711 * For each one-bit value {@code mb} of the mask, from least
1712 * significant to most significant, the bit value of {@code i} at
1713 * the same bit location as {@code mb} is assigned to the compressed
1714 * value contiguously starting from the least significant bit location.
1715 * All the upper remaining bits of the compressed value are set
1716 * to zero.
1717 *
1718 * @apiNote
1719 * Consider the simple case of compressing the digits of a hexadecimal
1720 * value:
1721 * {@snippet lang="java" :
1722 * // Compressing drink to food
1723 * compress(0xCAFEBABE, 0xFF00FFF0) == 0xCABAB
1724 * }
1725 * Starting from the least significant hexadecimal digit at position 0
1726 * from the right, the mask {@code 0xFF00FFF0} selects hexadecimal digits
1727 * at positions 1, 2, 3, 6 and 7 of {@code 0xCAFEBABE}. The selected digits
1728 * occur in the resulting compressed value contiguously from digit position
1729 * 0 in the same order.
1730 * <p>
1731 * The following identities all return {@code true} and are helpful to
1732 * understand the behaviour of {@code compress}:
1733 * {@snippet lang="java" :
1734 * // Returns 1 if the bit at position n is one
1735 * compress(x, 1 << n) == (x >> n & 1)
1736 *
1737 * // Logical shift right
1738 * compress(x, -1 << n) == x >>> n
1739 *
1740 * // Any bits not covered by the mask are ignored
1741 * compress(x, m) == compress(x & m, m)
1742 *
1743 * // Compressing a value by itself
1744 * compress(m, m) == (m == -1 || m == 0) ? m : (1 << bitCount(m)) - 1
1745 *
1746 * // Expanding then compressing with the same mask
1747 * compress(expand(x, m), m) == x & compress(m, m)
1748 * }
1749 * <p>
1750 * The Sheep And Goats (SAG) operation (see Hacker's Delight, Second Edition, section 7.7)
1751 * can be implemented as follows:
1752 * {@snippet lang="java" :
1753 * int compressLeft(int i, int mask) {
1754 * // This implementation follows the description in Hacker's Delight which
1755 * // is informative. A more optimal implementation is:
1756 * // Integer.compress(i, mask) << -Integer.bitCount(mask)
1757 * return Integer.reverse(
1758 * Integer.compress(Integer.reverse(i), Integer.reverse(mask)));
1759 * }
1760 *
1761 * int sag(int i, int mask) {
1762 * return compressLeft(i, mask) | Integer.compress(i, ~mask);
1763 * }
1764 *
1765 * // Separate the sheep from the goats
1766 * sag(0xCAFEBABE, 0xFF00FFF0) == 0xCABABFEE
1767 * }
1768 *
1769 * @param i the value whose bits are to be compressed
1770 * @param mask the bit mask
1771 * @return the compressed value
1772 * @see #expand
1773 * @since 19
1774 */
1775 @IntrinsicCandidate
1776 public static int compress(int i, int mask) {
1777 // See Hacker's Delight (2nd ed) section 7.4 Compress, or Generalized Extract
1778
1779 i = i & mask; // Clear irrelevant bits
1780 int maskCount = ~mask << 1; // Count 0's to right
1781
1782 for (int j = 0; j < 5; j++) {
1783 // Parallel prefix
1784 // Mask prefix identifies bits of the mask that have an odd number of 0's to the right
1785 int maskPrefix = parallelSuffix(maskCount);
1786 // Bits to move
1787 int maskMove = maskPrefix & mask;
1788 // Compress mask
1789 mask = (mask ^ maskMove) | (maskMove >>> (1 << j));
1790 // Bits of i to be moved
1791 int t = i & maskMove;
1792 // Compress i
1793 i = (i ^ t) | (t >>> (1 << j));
1794 // Adjust the mask count by identifying bits that have 0 to the right
1795 maskCount = maskCount & ~maskPrefix;
1796 }
1797 return i;
1798 }
1799
1800 /**
1801 * Returns the value obtained by expanding the bits of the
1802 * specified {@code int} value, {@code i}, in accordance with
1803 * the specified bit mask.
1804 * <p>
1805 * For each one-bit value {@code mb} of the mask, from least
1806 * significant to most significant, the next contiguous bit value
1807 * of {@code i} starting at the least significant bit is assigned
1808 * to the expanded value at the same bit location as {@code mb}.
1809 * All other remaining bits of the expanded value are set to zero.
1810 *
1811 * @apiNote
1812 * Consider the simple case of expanding the digits of a hexadecimal
1813 * value:
1814 * {@snippet lang="java" :
1815 * expand(0x0000CABAB, 0xFF00FFF0) == 0xCA00BAB0
1816 * }
1817 * Starting from the least significant hexadecimal digit at position 0
1818 * from the right, the mask {@code 0xFF00FFF0} selects the first five
1819 * hexadecimal digits of {@code 0x0000CABAB}. The selected digits occur
1820 * in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.
1821 * <p>
1822 * The following identities all return {@code true} and are helpful to
1823 * understand the behaviour of {@code expand}:
1824 * {@snippet lang="java" :
1825 * // Logically shift right the bit at position 0
1826 * expand(x, 1 << n) == (x & 1) << n
1827 *
1828 * // Logically shift right
1829 * expand(x, -1 << n) == x << n
1830 *
1831 * // Expanding all bits returns the mask
1832 * expand(-1, m) == m
1833 *
1834 * // Any bits not covered by the mask are ignored
1835 * expand(x, m) == expand(x, m) & m
1836 *
1837 * // Compressing then expanding with the same mask
1838 * expand(compress(x, m), m) == x & m
1839 * }
1840 * <p>
1841 * The select operation for determining the position of the one-bit with
1842 * index {@code n} in a {@code int} value can be implemented as follows:
1843 * {@snippet lang="java" :
1844 * int select(int i, int n) {
1845 * // the one-bit in i (the mask) with index n
1846 * int nthBit = Integer.expand(1 << n, i);
1847 * // the bit position of the one-bit with index n
1848 * return Integer.numberOfTrailingZeros(nthBit);
1849 * }
1850 *
1851 * // The one-bit with index 0 is at bit position 1
1852 * select(0b10101010_10101010, 0) == 1
1853 * // The one-bit with index 3 is at bit position 7
1854 * select(0b10101010_10101010, 3) == 7
1855 * }
1856 *
1857 * @param i the value whose bits are to be expanded
1858 * @param mask the bit mask
1859 * @return the expanded value
1860 * @see #compress
1861 * @since 19
1862 */
1863 @IntrinsicCandidate
1864 public static int expand(int i, int mask) {
1865 // Save original mask
1866 int originalMask = mask;
1867 // Count 0's to right
1868 int maskCount = ~mask << 1;
1869 int maskPrefix = parallelSuffix(maskCount);
1870 // Bits to move
1871 int maskMove1 = maskPrefix & mask;
1872 // Compress mask
1873 mask = (mask ^ maskMove1) | (maskMove1 >>> (1 << 0));
1874 maskCount = maskCount & ~maskPrefix;
1875
1876 maskPrefix = parallelSuffix(maskCount);
1877 // Bits to move
1878 int maskMove2 = maskPrefix & mask;
1879 // Compress mask
1880 mask = (mask ^ maskMove2) | (maskMove2 >>> (1 << 1));
1881 maskCount = maskCount & ~maskPrefix;
1882
1883 maskPrefix = parallelSuffix(maskCount);
1884 // Bits to move
1885 int maskMove3 = maskPrefix & mask;
1886 // Compress mask
1887 mask = (mask ^ maskMove3) | (maskMove3 >>> (1 << 2));
1888 maskCount = maskCount & ~maskPrefix;
1889
1890 maskPrefix = parallelSuffix(maskCount);
1891 // Bits to move
1892 int maskMove4 = maskPrefix & mask;
1893 // Compress mask
1894 mask = (mask ^ maskMove4) | (maskMove4 >>> (1 << 3));
1895 maskCount = maskCount & ~maskPrefix;
1896
1897 maskPrefix = parallelSuffix(maskCount);
1898 // Bits to move
1899 int maskMove5 = maskPrefix & mask;
1900
1901 int t = i << (1 << 4);
1902 i = (i & ~maskMove5) | (t & maskMove5);
1903 t = i << (1 << 3);
1904 i = (i & ~maskMove4) | (t & maskMove4);
1905 t = i << (1 << 2);
1906 i = (i & ~maskMove3) | (t & maskMove3);
1907 t = i << (1 << 1);
1908 i = (i & ~maskMove2) | (t & maskMove2);
1909 t = i << (1 << 0);
1910 i = (i & ~maskMove1) | (t & maskMove1);
1911
1912 // Clear irrelevant bits
1913 return i & originalMask;
1914 }
1915
1916 @ForceInline
1917 private static int parallelSuffix(int maskCount) {
1918 int maskPrefix = maskCount ^ (maskCount << 1);
1919 maskPrefix = maskPrefix ^ (maskPrefix << 2);
1920 maskPrefix = maskPrefix ^ (maskPrefix << 4);
1921 maskPrefix = maskPrefix ^ (maskPrefix << 8);
1922 maskPrefix = maskPrefix ^ (maskPrefix << 16);
1923 return maskPrefix;
1924 }
1925
1926 /**
1927 * Returns the signum function of the specified {@code int} value. (The
1928 * return value is -1 if the specified value is negative; 0 if the
1929 * specified value is zero; and 1 if the specified value is positive.)
1930 *
1931 * @param i the value whose signum is to be computed
1932 * @return the signum function of the specified {@code int} value.
1933 * @since 1.5
1934 */
1935 public static int signum(int i) {
1936 // HD, Section 2-7
1937 return (i >> 31) | (-i >>> 31);
1938 }
1939
1940 /**
1941 * Returns the value obtained by reversing the order of the bytes in the
1942 * two's complement representation of the specified {@code int} value.
1943 *
1944 * @param i the value whose bytes are to be reversed
1945 * @return the value obtained by reversing the bytes in the specified
1946 * {@code int} value.
1947 * @since 1.5
1948 */
1949 @IntrinsicCandidate
1950 public static int reverseBytes(int i) {
1951 return (i << 24) |
1952 ((i & 0xff00) << 8) |
1953 ((i >>> 8) & 0xff00) |
1954 (i >>> 24);
1955 }
1956
1957 /**
1958 * Adds two integers together as per the + operator.
1959 *
1960 * @param a the first operand
1961 * @param b the second operand
1962 * @return the sum of {@code a} and {@code b}
1963 * @see java.util.function.BinaryOperator
1964 * @since 1.8
1965 */
1966 public static int sum(int a, int b) {
1967 return a + b;
1968 }
1969
1970 /**
1971 * Returns the greater of two {@code int} values
1972 * as if by calling {@link Math#max(int, int) Math.max}.
1973 *
1974 * @param a the first operand
1975 * @param b the second operand
1976 * @return the greater of {@code a} and {@code b}
1977 * @see java.util.function.BinaryOperator
1978 * @since 1.8
1979 */
1980 public static int max(int a, int b) {
1981 return Math.max(a, b);
1982 }
1983
1984 /**
1985 * Returns the smaller of two {@code int} values
1986 * as if by calling {@link Math#min(int, int) Math.min}.
1987 *
1988 * @param a the first operand
1989 * @param b the second operand
1990 * @return the smaller of {@code a} and {@code b}
1991 * @see java.util.function.BinaryOperator
1992 * @since 1.8
1993 */
1994 public static int min(int a, int b) {
1995 return Math.min(a, b);
1996 }
1997
1998 /**
1999 * Returns an {@link Optional} containing the nominal descriptor for this
2000 * instance, which is the instance itself.
2001 *
2002 * @return an {@link Optional} describing the {@linkplain Integer} instance
2003 * @since 12
2004 */
2005 @Override
2006 public Optional<Integer> describeConstable() {
2007 return Optional.of(this);
2008 }
2009
2010 /**
2011 * Resolves this instance as a {@link ConstantDesc}, the result of which is
2012 * the instance itself.
2013 *
2014 * @param lookup ignored
2015 * @return the {@linkplain Integer} instance
2016 * @since 12
2017 */
2018 @Override
2019 public Integer resolveConstantDesc(MethodHandles.Lookup lookup) {
2020 return this;
2021 }
2022
2023 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2024 @java.io.Serial
2025 @Native private static final long serialVersionUID = 1360826667806852920L;
2026 }