1 /*
2 * Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import java.lang.annotation.Native;
29 import java.lang.invoke.MethodHandles;
30 import java.lang.constant.Constable;
31 import java.lang.constant.ConstantDesc;
32 import java.util.Objects;
33 import java.util.Optional;
34
35 import jdk.internal.HotSpotIntrinsicCandidate;
36 import jdk.internal.misc.VM;
37
38 import static java.lang.String.COMPACT_STRINGS;
39 import static java.lang.String.LATIN1;
40 import static java.lang.String.UTF16;
41
42 /**
43 * The {@code Integer} class wraps a value of the primitive type
44 * {@code int} in an object. An object of type {@code Integer}
45 * contains a single field whose type is {@code int}.
46 *
47 * <p>In addition, this class provides several methods for converting
48 * an {@code int} to a {@code String} and a {@code String} to an
49 * {@code int}, as well as other constants and methods useful when
50 * dealing with an {@code int}.
51 *
52 * <p>Implementation note: The implementations of the "bit twiddling"
53 * methods (such as {@link #highestOneBit(int) highestOneBit} and
54 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
55 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
56 * Delight</i>, (Addison Wesley, 2002).
57 *
58 * @author Lee Boynton
59 * @author Arthur van Hoff
60 * @author Josh Bloch
61 * @author Joseph D. Darcy
62 * @since 1.0
63 */
64 public final class Integer extends Number
65 implements Comparable<Integer>, Constable, ConstantDesc {
66 /**
67 * A constant holding the minimum value an {@code int} can
68 * have, -2<sup>31</sup>.
69 */
70 @Native public static final int MIN_VALUE = 0x80000000;
71
72 /**
73 * A constant holding the maximum value an {@code int} can
74 * have, 2<sup>31</sup>-1.
75 */
76 @Native public static final int MAX_VALUE = 0x7fffffff;
77
78 /**
79 * The {@code Class} instance representing the primitive type
80 * {@code int}.
81 *
82 * @since 1.1
83 */
84 @SuppressWarnings("unchecked")
85 public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
86
87 /**
88 * All possible chars for representing a number as a String
89 */
90 static final char[] digits = {
91 '0' , '1' , '2' , '3' , '4' , '5' ,
92 '6' , '7' , '8' , '9' , 'a' , 'b' ,
93 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
94 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
95 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
96 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
97 };
98
99 /**
100 * Returns a string representation of the first argument in the
101 * radix specified by the second argument.
102 *
103 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
104 * or larger than {@code Character.MAX_RADIX}, then the radix
105 * {@code 10} is used instead.
106 *
107 * <p>If the first argument is negative, the first element of the
108 * result is the ASCII minus character {@code '-'}
109 * ({@code '\u005Cu002D'}). If the first argument is not
110 * negative, no sign character appears in the result.
111 *
112 * <p>The remaining characters of the result represent the magnitude
113 * of the first argument. If the magnitude is zero, it is
114 * represented by a single zero character {@code '0'}
115 * ({@code '\u005Cu0030'}); otherwise, the first character of
116 * the representation of the magnitude will not be the zero
117 * character. The following ASCII characters are used as digits:
118 *
119 * <blockquote>
120 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
121 * </blockquote>
122 *
123 * These are {@code '\u005Cu0030'} through
124 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
125 * {@code '\u005Cu007A'}. If {@code radix} is
126 * <var>N</var>, then the first <var>N</var> of these characters
127 * are used as radix-<var>N</var> digits in the order shown. Thus,
128 * the digits for hexadecimal (radix 16) are
129 * {@code 0123456789abcdef}. If uppercase letters are
130 * desired, the {@link java.lang.String#toUpperCase()} method may
131 * be called on the result:
132 *
133 * <blockquote>
134 * {@code Integer.toString(n, 16).toUpperCase()}
135 * </blockquote>
136 *
137 * @param i an integer to be converted to a string.
138 * @param radix the radix to use in the string representation.
139 * @return a string representation of the argument in the specified radix.
140 * @see java.lang.Character#MAX_RADIX
141 * @see java.lang.Character#MIN_RADIX
142 */
143 public static String toString(int i, int radix) {
144 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
145 radix = 10;
146
147 /* Use the faster version */
148 if (radix == 10) {
149 return toString(i);
150 }
151
152 if (COMPACT_STRINGS) {
153 byte[] buf = new byte[33];
154 boolean negative = (i < 0);
155 int charPos = 32;
156
157 if (!negative) {
158 i = -i;
159 }
160
161 while (i <= -radix) {
162 buf[charPos--] = (byte)digits[-(i % radix)];
163 i = i / radix;
164 }
165 buf[charPos] = (byte)digits[-i];
166
167 if (negative) {
168 buf[--charPos] = '-';
169 }
170
171 return StringLatin1.newString(buf, charPos, (33 - charPos));
172 }
173 return toStringUTF16(i, radix);
174 }
175
176 private static String toStringUTF16(int i, int radix) {
177 byte[] buf = new byte[33 * 2];
178 boolean negative = (i < 0);
179 int charPos = 32;
180 if (!negative) {
181 i = -i;
182 }
183 while (i <= -radix) {
184 StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
185 i = i / radix;
186 }
187 StringUTF16.putChar(buf, charPos, digits[-i]);
188
189 if (negative) {
190 StringUTF16.putChar(buf, --charPos, '-');
191 }
192 return StringUTF16.newString(buf, charPos, (33 - charPos));
193 }
194
195 /**
196 * Returns a string representation of the first argument as an
197 * unsigned integer value in the radix specified by the second
198 * argument.
199 *
200 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
201 * or larger than {@code Character.MAX_RADIX}, then the radix
202 * {@code 10} is used instead.
203 *
204 * <p>Note that since the first argument is treated as an unsigned
205 * value, no leading sign character is printed.
206 *
207 * <p>If the magnitude is zero, it is represented by a single zero
208 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
209 * the first character of the representation of the magnitude will
210 * not be the zero character.
211 *
212 * <p>The behavior of radixes and the characters used as digits
213 * are the same as {@link #toString(int, int) toString}.
214 *
215 * @param i an integer to be converted to an unsigned string.
216 * @param radix the radix to use in the string representation.
217 * @return an unsigned string representation of the argument in the specified radix.
218 * @see #toString(int, int)
219 * @since 1.8
220 */
221 public static String toUnsignedString(int i, int radix) {
222 return Long.toUnsignedString(toUnsignedLong(i), radix);
223 }
224
225 /**
226 * Returns a string representation of the integer argument as an
227 * unsigned integer in base 16.
228 *
229 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
230 * if the argument is negative; otherwise, it is equal to the
231 * argument. This value is converted to a string of ASCII digits
232 * in hexadecimal (base 16) with no extra leading
233 * {@code 0}s.
234 *
235 * <p>The value of the argument can be recovered from the returned
236 * string {@code s} by calling {@link
237 * Integer#parseUnsignedInt(String, int)
238 * Integer.parseUnsignedInt(s, 16)}.
239 *
240 * <p>If the unsigned magnitude is zero, it is represented by a
241 * single zero character {@code '0'} ({@code '\u005Cu0030'});
242 * otherwise, the first character of the representation of the
243 * unsigned magnitude will not be the zero character. The
244 * following characters are used as hexadecimal digits:
245 *
246 * <blockquote>
247 * {@code 0123456789abcdef}
248 * </blockquote>
249 *
250 * These are the characters {@code '\u005Cu0030'} through
251 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
252 * {@code '\u005Cu0066'}. If uppercase letters are
253 * desired, the {@link java.lang.String#toUpperCase()} method may
254 * be called on the result:
255 *
256 * <blockquote>
257 * {@code Integer.toHexString(n).toUpperCase()}
258 * </blockquote>
259 *
260 * @param i an integer to be converted to a string.
261 * @return the string representation of the unsigned integer value
262 * represented by the argument in hexadecimal (base 16).
263 * @see #parseUnsignedInt(String, int)
264 * @see #toUnsignedString(int, int)
265 * @since 1.0.2
266 */
267 public static String toHexString(int i) {
268 return toUnsignedString0(i, 4);
269 }
270
271 /**
272 * Returns a string representation of the integer argument as an
273 * unsigned integer in base 8.
274 *
275 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
276 * if the argument is negative; otherwise, it is equal to the
277 * argument. This value is converted to a string of ASCII digits
278 * in octal (base 8) with no extra leading {@code 0}s.
279 *
280 * <p>The value of the argument can be recovered from the returned
281 * string {@code s} by calling {@link
282 * Integer#parseUnsignedInt(String, int)
283 * Integer.parseUnsignedInt(s, 8)}.
284 *
285 * <p>If the unsigned magnitude is zero, it is represented by a
286 * single zero character {@code '0'} ({@code '\u005Cu0030'});
287 * otherwise, the first character of the representation of the
288 * unsigned magnitude will not be the zero character. The
289 * following characters are used as octal digits:
290 *
291 * <blockquote>
292 * {@code 01234567}
293 * </blockquote>
294 *
295 * These are the characters {@code '\u005Cu0030'} through
296 * {@code '\u005Cu0037'}.
297 *
298 * @param i an integer to be converted to a string.
299 * @return the string representation of the unsigned integer value
300 * represented by the argument in octal (base 8).
301 * @see #parseUnsignedInt(String, int)
302 * @see #toUnsignedString(int, int)
303 * @since 1.0.2
304 */
305 public static String toOctalString(int i) {
306 return toUnsignedString0(i, 3);
307 }
308
309 /**
310 * Returns a string representation of the integer argument as an
311 * unsigned integer in base 2.
312 *
313 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
314 * if the argument is negative; otherwise it is equal to the
315 * argument. This value is converted to a string of ASCII digits
316 * in binary (base 2) with no extra leading {@code 0}s.
317 *
318 * <p>The value of the argument can be recovered from the returned
319 * string {@code s} by calling {@link
320 * Integer#parseUnsignedInt(String, int)
321 * Integer.parseUnsignedInt(s, 2)}.
322 *
323 * <p>If the unsigned magnitude is zero, it is represented by a
324 * single zero character {@code '0'} ({@code '\u005Cu0030'});
325 * otherwise, the first character of the representation of the
326 * unsigned magnitude will not be the zero character. The
327 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
328 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
329 *
330 * @param i an integer to be converted to a string.
331 * @return the string representation of the unsigned integer value
332 * represented by the argument in binary (base 2).
333 * @see #parseUnsignedInt(String, int)
334 * @see #toUnsignedString(int, int)
335 * @since 1.0.2
336 */
337 public static String toBinaryString(int i) {
338 return toUnsignedString0(i, 1);
339 }
340
341 /**
342 * Convert the integer to an unsigned number.
343 */
344 private static String toUnsignedString0(int val, int shift) {
345 // assert shift > 0 && shift <=5 : "Illegal shift value";
346 int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
347 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
348 if (COMPACT_STRINGS) {
349 byte[] buf = new byte[chars];
350 formatUnsignedInt(val, shift, buf, chars);
351 return new String(buf, LATIN1);
352 } else {
353 byte[] buf = new byte[chars * 2];
354 formatUnsignedIntUTF16(val, shift, buf, chars);
355 return new String(buf, UTF16);
356 }
357 }
358
359 /**
360 * Format an {@code int} (treated as unsigned) into a byte buffer (LATIN1 version). If
361 * {@code len} exceeds the formatted ASCII representation of {@code val},
362 * {@code buf} will be padded with leading zeroes.
363 *
364 * @param val the unsigned int to format
365 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
366 * @param buf the byte buffer to write to
367 * @param len the number of characters to write
368 */
369 private static void formatUnsignedInt(int val, int shift, byte[] buf, int len) {
370 int charPos = len;
371 int radix = 1 << shift;
372 int mask = radix - 1;
373 do {
374 buf[--charPos] = (byte)Integer.digits[val & mask];
375 val >>>= shift;
376 } while (charPos > 0);
377 }
378
379 /**
380 * Format an {@code int} (treated as unsigned) into a byte buffer (UTF16 version). If
381 * {@code len} exceeds the formatted ASCII representation of {@code val},
382 * {@code buf} will be padded with leading zeroes.
383 *
384 * @param val the unsigned int to format
385 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
386 * @param buf the byte buffer to write to
387 * @param len the number of characters to write
388 */
389 private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int len) {
390 int charPos = len;
391 int radix = 1 << shift;
392 int mask = radix - 1;
393 do {
394 StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
395 val >>>= shift;
396 } while (charPos > 0);
397 }
398
399 static final byte[] DigitTens = {
400 '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
401 '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
402 '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
403 '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
404 '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
405 '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
406 '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
407 '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
408 '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
409 '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
410 } ;
411
412 static final byte[] DigitOnes = {
413 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
414 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
415 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
416 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
417 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
418 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
419 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
420 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
421 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
422 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
423 } ;
424
425
426 /**
427 * Returns a {@code String} object representing the
428 * specified integer. The argument is converted to signed decimal
429 * representation and returned as a string, exactly as if the
430 * argument and radix 10 were given as arguments to the {@link
431 * #toString(int, int)} method.
432 *
433 * @param i an integer to be converted.
434 * @return a string representation of the argument in base 10.
435 */
436 @HotSpotIntrinsicCandidate
437 public static String toString(int i) {
438 int size = stringSize(i);
439 if (COMPACT_STRINGS) {
440 byte[] buf = new byte[size];
441 getChars(i, size, buf);
442 return new String(buf, LATIN1);
443 } else {
444 byte[] buf = new byte[size * 2];
445 StringUTF16.getChars(i, size, buf);
446 return new String(buf, UTF16);
447 }
448 }
449
450 /**
451 * Returns a string representation of the argument as an unsigned
452 * decimal value.
453 *
454 * The argument is converted to unsigned decimal representation
455 * and returned as a string exactly as if the argument and radix
456 * 10 were given as arguments to the {@link #toUnsignedString(int,
457 * int)} method.
458 *
459 * @param i an integer to be converted to an unsigned string.
460 * @return an unsigned string representation of the argument.
461 * @see #toUnsignedString(int, int)
462 * @since 1.8
463 */
464 public static String toUnsignedString(int i) {
465 return Long.toString(toUnsignedLong(i));
466 }
467
468 /**
469 * Places characters representing the integer i into the
470 * character array buf. The characters are placed into
471 * the buffer backwards starting with the least significant
472 * digit at the specified index (exclusive), and working
473 * backwards from there.
474 *
475 * @implNote This method converts positive inputs into negative
476 * values, to cover the Integer.MIN_VALUE case. Converting otherwise
477 * (negative to positive) will expose -Integer.MIN_VALUE that overflows
478 * integer.
479 *
480 * @param i value to convert
481 * @param index next index, after the least significant digit
482 * @param buf target buffer, Latin1-encoded
483 * @return index of the most significant digit or minus sign, if present
484 */
485 static int getChars(int i, int index, byte[] buf) {
486 int q, r;
487 int charPos = index;
488
489 boolean negative = i < 0;
490 if (!negative) {
491 i = -i;
492 }
493
494 // Generate two digits per iteration
495 while (i <= -100) {
496 q = i / 100;
497 r = (q * 100) - i;
498 i = q;
499 buf[--charPos] = DigitOnes[r];
500 buf[--charPos] = DigitTens[r];
501 }
502
503 // We know there are at most two digits left at this point.
504 q = i / 10;
505 r = (q * 10) - i;
506 buf[--charPos] = (byte)('0' + r);
507
508 // Whatever left is the remaining digit.
509 if (q < 0) {
510 buf[--charPos] = (byte)('0' - q);
511 }
512
513 if (negative) {
514 buf[--charPos] = (byte)'-';
515 }
516 return charPos;
517 }
518
519 // Left here for compatibility reasons, see JDK-8143900.
520 static final int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
521 99999999, 999999999, Integer.MAX_VALUE };
522
523 /**
524 * Returns the string representation size for a given int value.
525 *
526 * @param x int value
527 * @return string size
528 *
529 * @implNote There are other ways to compute this: e.g. binary search,
530 * but values are biased heavily towards zero, and therefore linear search
531 * wins. The iteration results are also routinely inlined in the generated
532 * code after loop unrolling.
533 */
534 static int stringSize(int x) {
535 int d = 1;
536 if (x >= 0) {
537 d = 0;
538 x = -x;
539 }
540 int p = -10;
541 for (int i = 1; i < 10; i++) {
542 if (x > p)
543 return i + d;
544 p = 10 * p;
545 }
546 return 10 + d;
547 }
548
549 /**
550 * Parses the string argument as a signed integer in the radix
551 * specified by the second argument. The characters in the string
552 * must all be digits of the specified radix (as determined by
553 * whether {@link java.lang.Character#digit(char, int)} returns a
554 * nonnegative value), except that the first character may be an
555 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
556 * indicate a negative value or an ASCII plus sign {@code '+'}
557 * ({@code '\u005Cu002B'}) to indicate a positive value. The
558 * resulting integer value is returned.
559 *
560 * <p>An exception of type {@code NumberFormatException} is
561 * thrown if any of the following situations occurs:
562 * <ul>
563 * <li>The first argument is {@code null} or is a string of
564 * length zero.
565 *
566 * <li>The radix is either smaller than
567 * {@link java.lang.Character#MIN_RADIX} or
568 * larger than {@link java.lang.Character#MAX_RADIX}.
569 *
570 * <li>Any character of the string is not a digit of the specified
571 * radix, except that the first character may be a minus sign
572 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign
573 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
574 * string is longer than length 1.
575 *
576 * <li>The value represented by the string is not a value of type
577 * {@code int}.
578 * </ul>
579 *
580 * <p>Examples:
581 * <blockquote><pre>
582 * parseInt("0", 10) returns 0
583 * parseInt("473", 10) returns 473
584 * parseInt("+42", 10) returns 42
585 * parseInt("-0", 10) returns 0
586 * parseInt("-FF", 16) returns -255
587 * parseInt("1100110", 2) returns 102
588 * parseInt("2147483647", 10) returns 2147483647
589 * parseInt("-2147483648", 10) returns -2147483648
590 * parseInt("2147483648", 10) throws a NumberFormatException
591 * parseInt("99", 8) throws a NumberFormatException
592 * parseInt("Kona", 10) throws a NumberFormatException
593 * parseInt("Kona", 27) returns 411787
594 * </pre></blockquote>
595 *
596 * @param s the {@code String} containing the integer
597 * representation to be parsed
598 * @param radix the radix to be used while parsing {@code s}.
599 * @return the integer represented by the string argument in the
600 * specified radix.
601 * @throws NumberFormatException if the {@code String}
602 * does not contain a parsable {@code int}.
603 */
604 public static int parseInt(String s, int radix)
605 throws NumberFormatException
606 {
607 /*
608 * WARNING: This method may be invoked early during VM initialization
609 * before IntegerCache is initialized. Care must be taken to not use
610 * the valueOf method.
611 */
612
613 if (s == null) {
614 throw new NumberFormatException("null");
615 }
616
617 if (radix < Character.MIN_RADIX) {
618 throw new NumberFormatException("radix " + radix +
619 " less than Character.MIN_RADIX");
620 }
621
622 if (radix > Character.MAX_RADIX) {
623 throw new NumberFormatException("radix " + radix +
624 " greater than Character.MAX_RADIX");
625 }
626
627 boolean negative = false;
628 int i = 0, len = s.length();
629 int limit = -Integer.MAX_VALUE;
630
631 if (len > 0) {
632 char firstChar = s.charAt(0);
633 if (firstChar < '0') { // Possible leading "+" or "-"
634 if (firstChar == '-') {
635 negative = true;
636 limit = Integer.MIN_VALUE;
637 } else if (firstChar != '+') {
638 throw NumberFormatException.forInputString(s, radix);
639 }
640
641 if (len == 1) { // Cannot have lone "+" or "-"
642 throw NumberFormatException.forInputString(s, radix);
643 }
644 i++;
645 }
646 int multmin = limit / radix;
647 int result = 0;
648 while (i < len) {
649 // Accumulating negatively avoids surprises near MAX_VALUE
650 int digit = Character.digit(s.charAt(i++), radix);
651 if (digit < 0 || result < multmin) {
652 throw NumberFormatException.forInputString(s, radix);
653 }
654 result *= radix;
655 if (result < limit + digit) {
656 throw NumberFormatException.forInputString(s, radix);
657 }
658 result -= digit;
659 }
660 return negative ? result : -result;
661 } else {
662 throw NumberFormatException.forInputString(s, radix);
663 }
664 }
665
666 /**
667 * Parses the {@link CharSequence} argument as a signed {@code int} in the
668 * specified {@code radix}, beginning at the specified {@code beginIndex}
669 * and extending to {@code endIndex - 1}.
670 *
671 * <p>The method does not take steps to guard against the
672 * {@code CharSequence} being mutated while parsing.
673 *
674 * @param s the {@code CharSequence} containing the {@code int}
675 * representation to be parsed
676 * @param beginIndex the beginning index, inclusive.
677 * @param endIndex the ending index, exclusive.
678 * @param radix the radix to be used while parsing {@code s}.
679 * @return the signed {@code int} represented by the subsequence in
680 * the specified radix.
681 * @throws NullPointerException if {@code s} is null.
682 * @throws IndexOutOfBoundsException if {@code beginIndex} is
683 * negative, or if {@code beginIndex} is greater than
684 * {@code endIndex} or if {@code endIndex} is greater than
685 * {@code s.length()}.
686 * @throws NumberFormatException if the {@code CharSequence} does not
687 * contain a parsable {@code int} in the specified
688 * {@code radix}, or if {@code radix} is either smaller than
689 * {@link java.lang.Character#MIN_RADIX} or larger than
690 * {@link java.lang.Character#MAX_RADIX}.
691 * @since 9
692 */
693 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
694 throws NumberFormatException {
695 Objects.requireNonNull(s);
696
697 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
698 throw new IndexOutOfBoundsException();
699 }
700 if (radix < Character.MIN_RADIX) {
701 throw new NumberFormatException("radix " + radix +
702 " less than Character.MIN_RADIX");
703 }
704 if (radix > Character.MAX_RADIX) {
705 throw new NumberFormatException("radix " + radix +
706 " greater than Character.MAX_RADIX");
707 }
708
709 boolean negative = false;
710 int i = beginIndex;
711 int limit = -Integer.MAX_VALUE;
712
713 if (i < endIndex) {
714 char firstChar = s.charAt(i);
715 if (firstChar < '0') { // Possible leading "+" or "-"
716 if (firstChar == '-') {
717 negative = true;
718 limit = Integer.MIN_VALUE;
719 } else if (firstChar != '+') {
720 throw NumberFormatException.forCharSequence(s, beginIndex,
721 endIndex, i);
722 }
723 i++;
724 if (i == endIndex) { // Cannot have lone "+" or "-"
725 throw NumberFormatException.forCharSequence(s, beginIndex,
726 endIndex, i);
727 }
728 }
729 int multmin = limit / radix;
730 int result = 0;
731 while (i < endIndex) {
732 // Accumulating negatively avoids surprises near MAX_VALUE
733 int digit = Character.digit(s.charAt(i), radix);
734 if (digit < 0 || result < multmin) {
735 throw NumberFormatException.forCharSequence(s, beginIndex,
736 endIndex, i);
737 }
738 result *= radix;
739 if (result < limit + digit) {
740 throw NumberFormatException.forCharSequence(s, beginIndex,
741 endIndex, i);
742 }
743 i++;
744 result -= digit;
745 }
746 return negative ? result : -result;
747 } else {
748 throw NumberFormatException.forInputString("", radix);
749 }
750 }
751
752 /**
753 * Parses the string argument as a signed decimal integer. The
754 * characters in the string must all be decimal digits, except
755 * that the first character may be an ASCII minus sign {@code '-'}
756 * ({@code '\u005Cu002D'}) to indicate a negative value or an
757 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
758 * indicate a positive value. The resulting integer value is
759 * returned, exactly as if the argument and the radix 10 were
760 * given as arguments to the {@link #parseInt(java.lang.String,
761 * int)} method.
762 *
763 * @param s a {@code String} containing the {@code int}
764 * representation to be parsed
765 * @return the integer value represented by the argument in decimal.
766 * @throws NumberFormatException if the string does not contain a
767 * parsable integer.
768 */
769 public static int parseInt(String s) throws NumberFormatException {
770 return parseInt(s,10);
771 }
772
773 /**
774 * Parses the string argument as an unsigned integer in the radix
775 * specified by the second argument. An unsigned integer maps the
776 * values usually associated with negative numbers to positive
777 * numbers larger than {@code MAX_VALUE}.
778 *
779 * The characters in the string must all be digits of the
780 * specified radix (as determined by whether {@link
781 * java.lang.Character#digit(char, int)} returns a nonnegative
782 * value), except that the first character may be an ASCII plus
783 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
784 * integer value is returned.
785 *
786 * <p>An exception of type {@code NumberFormatException} is
787 * thrown if any of the following situations occurs:
788 * <ul>
789 * <li>The first argument is {@code null} or is a string of
790 * length zero.
791 *
792 * <li>The radix is either smaller than
793 * {@link java.lang.Character#MIN_RADIX} or
794 * larger than {@link java.lang.Character#MAX_RADIX}.
795 *
796 * <li>Any character of the string is not a digit of the specified
797 * radix, except that the first character may be a plus sign
798 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
799 * string is longer than length 1.
800 *
801 * <li>The value represented by the string is larger than the
802 * largest unsigned {@code int}, 2<sup>32</sup>-1.
803 *
804 * </ul>
805 *
806 *
807 * @param s the {@code String} containing the unsigned integer
808 * representation to be parsed
809 * @param radix the radix to be used while parsing {@code s}.
810 * @return the integer represented by the string argument in the
811 * specified radix.
812 * @throws NumberFormatException if the {@code String}
813 * does not contain a parsable {@code int}.
814 * @since 1.8
815 */
816 public static int parseUnsignedInt(String s, int radix)
817 throws NumberFormatException {
818 if (s == null) {
819 throw new NumberFormatException("null");
820 }
821
822 int len = s.length();
823 if (len > 0) {
824 char firstChar = s.charAt(0);
825 if (firstChar == '-') {
826 throw new
827 NumberFormatException(String.format("Illegal leading minus sign " +
828 "on unsigned string %s.", s));
829 } else {
830 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
831 (radix == 10 && len <= 9) ) { // Integer.MAX_VALUE in base 10 is 10 digits
832 return parseInt(s, radix);
833 } else {
834 long ell = Long.parseLong(s, radix);
835 if ((ell & 0xffff_ffff_0000_0000L) == 0) {
836 return (int) ell;
837 } else {
838 throw new
839 NumberFormatException(String.format("String value %s exceeds " +
840 "range of unsigned int.", s));
841 }
842 }
843 }
844 } else {
845 throw NumberFormatException.forInputString(s, radix);
846 }
847 }
848
849 /**
850 * Parses the {@link CharSequence} argument as an unsigned {@code int} in
851 * the specified {@code radix}, beginning at the specified
852 * {@code beginIndex} and extending to {@code endIndex - 1}.
853 *
854 * <p>The method does not take steps to guard against the
855 * {@code CharSequence} being mutated while parsing.
856 *
857 * @param s the {@code CharSequence} containing the unsigned
858 * {@code int} representation to be parsed
859 * @param beginIndex the beginning index, inclusive.
860 * @param endIndex the ending index, exclusive.
861 * @param radix the radix to be used while parsing {@code s}.
862 * @return the unsigned {@code int} represented by the subsequence in
863 * the specified radix.
864 * @throws NullPointerException if {@code s} is null.
865 * @throws IndexOutOfBoundsException if {@code beginIndex} is
866 * negative, or if {@code beginIndex} is greater than
867 * {@code endIndex} or if {@code endIndex} is greater than
868 * {@code s.length()}.
869 * @throws NumberFormatException if the {@code CharSequence} does not
870 * contain a parsable unsigned {@code int} in the specified
871 * {@code radix}, or if {@code radix} is either smaller than
872 * {@link java.lang.Character#MIN_RADIX} or larger than
873 * {@link java.lang.Character#MAX_RADIX}.
874 * @since 9
875 */
876 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
877 throws NumberFormatException {
878 Objects.requireNonNull(s);
879
880 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
881 throw new IndexOutOfBoundsException();
882 }
883 int start = beginIndex, len = endIndex - beginIndex;
884
885 if (len > 0) {
886 char firstChar = s.charAt(start);
887 if (firstChar == '-') {
888 throw new
889 NumberFormatException(String.format("Illegal leading minus sign " +
890 "on unsigned string %s.", s));
891 } else {
892 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
893 (radix == 10 && len <= 9)) { // Integer.MAX_VALUE in base 10 is 10 digits
894 return parseInt(s, start, start + len, radix);
895 } else {
896 long ell = Long.parseLong(s, start, start + len, radix);
897 if ((ell & 0xffff_ffff_0000_0000L) == 0) {
898 return (int) ell;
899 } else {
900 throw new
901 NumberFormatException(String.format("String value %s exceeds " +
902 "range of unsigned int.", s));
903 }
904 }
905 }
906 } else {
907 throw new NumberFormatException("");
908 }
909 }
910
911 /**
912 * Parses the string argument as an unsigned decimal integer. The
913 * characters in the string must all be decimal digits, except
914 * that the first character may be an ASCII plus sign {@code
915 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
916 * is returned, exactly as if the argument and the radix 10 were
917 * given as arguments to the {@link
918 * #parseUnsignedInt(java.lang.String, int)} method.
919 *
920 * @param s a {@code String} containing the unsigned {@code int}
921 * representation to be parsed
922 * @return the unsigned integer value represented by the argument in decimal.
923 * @throws NumberFormatException if the string does not contain a
924 * parsable unsigned integer.
925 * @since 1.8
926 */
927 public static int parseUnsignedInt(String s) throws NumberFormatException {
928 return parseUnsignedInt(s, 10);
929 }
930
931 /**
932 * Returns an {@code Integer} object holding the value
933 * extracted from the specified {@code String} when parsed
934 * with the radix given by the second argument. The first argument
935 * is interpreted as representing a signed integer in the radix
936 * specified by the second argument, exactly as if the arguments
937 * were given to the {@link #parseInt(java.lang.String, int)}
938 * method. The result is an {@code Integer} object that
939 * represents the integer value specified by the string.
940 *
941 * <p>In other words, this method returns an {@code Integer}
942 * object equal to the value of:
943 *
944 * <blockquote>
945 * {@code new Integer(Integer.parseInt(s, radix))}
946 * </blockquote>
947 *
948 * @param s the string to be parsed.
949 * @param radix the radix to be used in interpreting {@code s}
950 * @return an {@code Integer} object holding the value
951 * represented by the string argument in the specified
952 * radix.
953 * @throws NumberFormatException if the {@code String}
954 * does not contain a parsable {@code int}.
955 */
956 public static Integer valueOf(String s, int radix) throws NumberFormatException {
957 return Integer.valueOf(parseInt(s,radix));
958 }
959
960 /**
961 * Returns an {@code Integer} object holding the
962 * value of the specified {@code String}. The argument is
963 * interpreted as representing a signed decimal integer, exactly
964 * as if the argument were given to the {@link
965 * #parseInt(java.lang.String)} method. The result is an
966 * {@code Integer} object that represents the integer value
967 * specified by the string.
968 *
969 * <p>In other words, this method returns an {@code Integer}
970 * object equal to the value of:
971 *
972 * <blockquote>
973 * {@code new Integer(Integer.parseInt(s))}
974 * </blockquote>
975 *
976 * @param s the string to be parsed.
977 * @return an {@code Integer} object holding the value
978 * represented by the string argument.
979 * @throws NumberFormatException if the string cannot be parsed
980 * as an integer.
981 */
982 public static Integer valueOf(String s) throws NumberFormatException {
983 return Integer.valueOf(parseInt(s, 10));
984 }
985
986 /**
987 * Cache to support the object identity semantics of autoboxing for values between
988 * -128 and 127 (inclusive) as required by JLS.
989 *
990 * The cache is initialized on first usage. The size of the cache
991 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
992 * During VM initialization, java.lang.Integer.IntegerCache.high property
993 * may be set and saved in the private system properties in the
994 * jdk.internal.misc.VM class.
995 *
996 * WARNING: The cache is archived with CDS and reloaded from the shared
997 * archive at runtime. The archived cache (Integer[]) and Integer objects
998 * reside in the closed archive heap regions. Care should be taken when
999 * changing the implementation and the cache array should not be assigned
1000 * with new Integer object(s) after initialization.
1001 */
1002
1003 private static class IntegerCache {
1004 static final int low = -128;
1005 static final int high;
1006 static final Integer[] cache;
1007 static Integer[] archivedCache;
1008
1009 static {
1010 // high value may be configured by property
1011 int h = 127;
1012 String integerCacheHighPropValue =
1013 VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
1014 if (integerCacheHighPropValue != null) {
1015 try {
1016 h = Math.max(parseInt(integerCacheHighPropValue), 127);
1017 // Maximum array size is Integer.MAX_VALUE
1018 h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
1019 } catch( NumberFormatException nfe) {
1020 // If the property cannot be parsed into an int, ignore it.
1021 }
1022 }
1023 high = h;
1024
1025 // Load IntegerCache.archivedCache from archive, if possible
1026 VM.initializeFromArchive(IntegerCache.class);
1027 int size = (high - low) + 1;
1028
1029 // Use the archived cache if it exists and is large enough
1030 if (archivedCache == null || size > archivedCache.length) {
1031 Integer[] c = new Integer[size];
1032 int j = low;
1033 for(int i = 0; i < c.length; i++) {
1034 c[i] = new Integer(j++);
1035 }
1036 archivedCache = c;
1037 }
1038 cache = archivedCache;
1039 // range [-128, 127] must be interned (JLS7 5.1.7)
1040 assert IntegerCache.high >= 127;
1041 }
1042
1043 private IntegerCache() {}
1044 }
1045
1046 /**
1047 * Returns an {@code Integer} instance representing the specified
1048 * {@code int} value. If a new {@code Integer} instance is not
1049 * required, this method should generally be used in preference to
1050 * the constructor {@link #Integer(int)}, as this method is likely
1051 * to yield significantly better space and time performance by
1052 * caching frequently requested values.
1053 *
1054 * This method will always cache values in the range -128 to 127,
1055 * inclusive, and may cache other values outside of this range.
1056 *
1057 * @param i an {@code int} value.
1058 * @return an {@code Integer} instance representing {@code i}.
1059 * @since 1.5
1060 */
1061 @HotSpotIntrinsicCandidate
1062 public static Integer valueOf(int i) {
1063 if (i >= IntegerCache.low && i <= IntegerCache.high)
1064 return IntegerCache.cache[i + (-IntegerCache.low)];
1065 return new Integer(i);
1066 }
1067
1068 /**
1069 * The value of the {@code Integer}.
1070 *
1071 * @serial
1072 */
1073 private final int value;
1074
1075 /**
1076 * Constructs a newly allocated {@code Integer} object that
1077 * represents the specified {@code int} value.
1078 *
1079 * @param value the value to be represented by the
1080 * {@code Integer} object.
1081 *
1082 * @deprecated
1083 * It is rarely appropriate to use this constructor. The static factory
1084 * {@link #valueOf(int)} is generally a better choice, as it is
1085 * likely to yield significantly better space and time performance.
1086 */
1087 @Deprecated(since="9")
1088 public Integer(int value) {
1089 this.value = value;
1090 }
1091
1092 /**
1093 * Constructs a newly allocated {@code Integer} object that
1094 * represents the {@code int} value indicated by the
1095 * {@code String} parameter. The string is converted to an
1096 * {@code int} value in exactly the manner used by the
1097 * {@code parseInt} method for radix 10.
1098 *
1099 * @param s the {@code String} to be converted to an {@code Integer}.
1100 * @throws NumberFormatException if the {@code String} does not
1101 * contain a parsable integer.
1102 *
1103 * @deprecated
1104 * It is rarely appropriate to use this constructor.
1105 * Use {@link #parseInt(String)} to convert a string to a
1106 * {@code int} primitive, or use {@link #valueOf(String)}
1107 * to convert a string to an {@code Integer} object.
1108 */
1109 @Deprecated(since="9")
1110 public Integer(String s) throws NumberFormatException {
1111 this.value = parseInt(s, 10);
1112 }
1113
1114 /**
1115 * Returns the value of this {@code Integer} as a {@code byte}
1116 * after a narrowing primitive conversion.
1117 * @jls 5.1.3 Narrowing Primitive Conversion
1118 */
1119 public byte byteValue() {
1120 return (byte)value;
1121 }
1122
1123 /**
1124 * Returns the value of this {@code Integer} as a {@code short}
1125 * after a narrowing primitive conversion.
1126 * @jls 5.1.3 Narrowing Primitive Conversion
1127 */
1128 public short shortValue() {
1129 return (short)value;
1130 }
1131
1132 /**
1133 * Returns the value of this {@code Integer} as an
1134 * {@code int}.
1135 */
1136 @HotSpotIntrinsicCandidate
1137 public int intValue() {
1138 return value;
1139 }
1140
1141 /**
1142 * Returns the value of this {@code Integer} as a {@code long}
1143 * after a widening primitive conversion.
1144 * @jls 5.1.2 Widening Primitive Conversion
1145 * @see Integer#toUnsignedLong(int)
1146 */
1147 public long longValue() {
1148 return (long)value;
1149 }
1150
1151 /**
1152 * Returns the value of this {@code Integer} as a {@code float}
1153 * after a widening primitive conversion.
1154 * @jls 5.1.2 Widening Primitive Conversion
1155 */
1156 public float floatValue() {
1157 return (float)value;
1158 }
1159
1160 /**
1161 * Returns the value of this {@code Integer} as a {@code double}
1162 * after a widening primitive conversion.
1163 * @jls 5.1.2 Widening Primitive Conversion
1164 */
1165 public double doubleValue() {
1166 return (double)value;
1167 }
1168
1169 /**
1170 * Returns a {@code String} object representing this
1171 * {@code Integer}'s value. The value is converted to signed
1172 * decimal representation and returned as a string, exactly as if
1173 * the integer value were given as an argument to the {@link
1174 * java.lang.Integer#toString(int)} method.
1175 *
1176 * @return a string representation of the value of this object in
1177 * base 10.
1178 */
1179 public String toString() {
1180 return toString(value);
1181 }
1182
1183 /**
1184 * Returns a hash code for this {@code Integer}.
1185 *
1186 * @return a hash code value for this object, equal to the
1187 * primitive {@code int} value represented by this
1188 * {@code Integer} object.
1189 */
1190 @Override
1191 public int hashCode() {
1192 return Integer.hashCode(value);
1193 }
1194
1195 /**
1196 * Returns a hash code for an {@code int} value; compatible with
1197 * {@code Integer.hashCode()}.
1198 *
1199 * @param value the value to hash
1200 * @since 1.8
1201 *
1202 * @return a hash code value for an {@code int} value.
1203 */
1204 public static int hashCode(int value) {
1205 return value;
1206 }
1207
1208 /**
1209 * Compares this object to the specified object. The result is
1210 * {@code true} if and only if the argument is not
1211 * {@code null} and is an {@code Integer} object that
1212 * contains the same {@code int} value as this object.
1213 *
1214 * @param obj the object to compare with.
1215 * @return {@code true} if the objects are the same;
1216 * {@code false} otherwise.
1217 */
1218 public boolean equals(Object obj) {
1219 if (obj instanceof Integer) {
1220 return value == ((Integer)obj).intValue();
1221 }
1222 return false;
1223 }
1224
1225 /**
1226 * Determines the integer value of the system property with the
1227 * specified name.
1228 *
1229 * <p>The first argument is treated as the name of a system
1230 * property. System properties are accessible through the {@link
1231 * java.lang.System#getProperty(java.lang.String)} method. The
1232 * string value of this property is then interpreted as an integer
1233 * value using the grammar supported by {@link Integer#decode decode} and
1234 * an {@code Integer} object representing this value is returned.
1235 *
1236 * <p>If there is no property with the specified name, if the
1237 * specified name is empty or {@code null}, or if the property
1238 * does not have the correct numeric format, then {@code null} is
1239 * returned.
1240 *
1241 * <p>In other words, this method returns an {@code Integer}
1242 * object equal to the value of:
1243 *
1244 * <blockquote>
1245 * {@code getInteger(nm, null)}
1246 * </blockquote>
1247 *
1248 * @param nm property name.
1249 * @return the {@code Integer} value of the property.
1250 * @throws SecurityException for the same reasons as
1251 * {@link System#getProperty(String) System.getProperty}
1252 * @see java.lang.System#getProperty(java.lang.String)
1253 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1254 */
1255 public static Integer getInteger(String nm) {
1256 return getInteger(nm, null);
1257 }
1258
1259 /**
1260 * Determines the integer value of the system property with the
1261 * specified name.
1262 *
1263 * <p>The first argument is treated as the name of a system
1264 * property. System properties are accessible through the {@link
1265 * java.lang.System#getProperty(java.lang.String)} method. The
1266 * string value of this property is then interpreted as an integer
1267 * value using the grammar supported by {@link Integer#decode decode} and
1268 * an {@code Integer} object representing this value is returned.
1269 *
1270 * <p>The second argument is the default value. An {@code Integer} object
1271 * that represents the value of the second argument is returned if there
1272 * is no property of the specified name, if the property does not have
1273 * the correct numeric format, or if the specified name is empty or
1274 * {@code null}.
1275 *
1276 * <p>In other words, this method returns an {@code Integer} object
1277 * equal to the value of:
1278 *
1279 * <blockquote>
1280 * {@code getInteger(nm, new Integer(val))}
1281 * </blockquote>
1282 *
1283 * but in practice it may be implemented in a manner such as:
1284 *
1285 * <blockquote><pre>
1286 * Integer result = getInteger(nm, null);
1287 * return (result == null) ? new Integer(val) : result;
1288 * </pre></blockquote>
1289 *
1290 * to avoid the unnecessary allocation of an {@code Integer}
1291 * object when the default value is not needed.
1292 *
1293 * @param nm property name.
1294 * @param val default value.
1295 * @return the {@code Integer} value of the property.
1296 * @throws SecurityException for the same reasons as
1297 * {@link System#getProperty(String) System.getProperty}
1298 * @see java.lang.System#getProperty(java.lang.String)
1299 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1300 */
1301 public static Integer getInteger(String nm, int val) {
1302 Integer result = getInteger(nm, null);
1303 return (result == null) ? Integer.valueOf(val) : result;
1304 }
1305
1306 /**
1307 * Returns the integer value of the system property with the
1308 * specified name. The first argument is treated as the name of a
1309 * system property. System properties are accessible through the
1310 * {@link java.lang.System#getProperty(java.lang.String)} method.
1311 * The string value of this property is then interpreted as an
1312 * integer value, as per the {@link Integer#decode decode} method,
1313 * and an {@code Integer} object representing this value is
1314 * returned; in summary:
1315 *
1316 * <ul><li>If the property value begins with the two ASCII characters
1317 * {@code 0x} or the ASCII character {@code #}, not
1318 * followed by a minus sign, then the rest of it is parsed as a
1319 * hexadecimal integer exactly as by the method
1320 * {@link #valueOf(java.lang.String, int)} with radix 16.
1321 * <li>If the property value begins with the ASCII character
1322 * {@code 0} followed by another character, it is parsed as an
1323 * octal integer exactly as by the method
1324 * {@link #valueOf(java.lang.String, int)} with radix 8.
1325 * <li>Otherwise, the property value is parsed as a decimal integer
1326 * exactly as by the method {@link #valueOf(java.lang.String, int)}
1327 * with radix 10.
1328 * </ul>
1329 *
1330 * <p>The second argument is the default value. The default value is
1331 * returned if there is no property of the specified name, if the
1332 * property does not have the correct numeric format, or if the
1333 * specified name is empty or {@code null}.
1334 *
1335 * @param nm property name.
1336 * @param val default value.
1337 * @return the {@code Integer} value of the property.
1338 * @throws SecurityException for the same reasons as
1339 * {@link System#getProperty(String) System.getProperty}
1340 * @see System#getProperty(java.lang.String)
1341 * @see System#getProperty(java.lang.String, java.lang.String)
1342 */
1343 public static Integer getInteger(String nm, Integer val) {
1344 String v = null;
1345 try {
1346 v = System.getProperty(nm);
1347 } catch (IllegalArgumentException | NullPointerException e) {
1348 }
1349 if (v != null) {
1350 try {
1351 return Integer.decode(v);
1352 } catch (NumberFormatException e) {
1353 }
1354 }
1355 return val;
1356 }
1357
1358 /**
1359 * Decodes a {@code String} into an {@code Integer}.
1360 * Accepts decimal, hexadecimal, and octal numbers given
1361 * by the following grammar:
1362 *
1363 * <blockquote>
1364 * <dl>
1365 * <dt><i>DecodableString:</i>
1366 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1367 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1368 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1369 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1370 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1371 *
1372 * <dt><i>Sign:</i>
1373 * <dd>{@code -}
1374 * <dd>{@code +}
1375 * </dl>
1376 * </blockquote>
1377 *
1378 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1379 * are as defined in section 3.10.1 of
1380 * <cite>The Java Language Specification</cite>,
1381 * except that underscores are not accepted between digits.
1382 *
1383 * <p>The sequence of characters following an optional
1384 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1385 * "{@code #}", or leading zero) is parsed as by the {@code
1386 * Integer.parseInt} method with the indicated radix (10, 16, or
1387 * 8). This sequence of characters must represent a positive
1388 * value or a {@link NumberFormatException} will be thrown. The
1389 * result is negated if first character of the specified {@code
1390 * String} is the minus sign. No whitespace characters are
1391 * permitted in the {@code String}.
1392 *
1393 * @param nm the {@code String} to decode.
1394 * @return an {@code Integer} object holding the {@code int}
1395 * value represented by {@code nm}
1396 * @throws NumberFormatException if the {@code String} does not
1397 * contain a parsable integer.
1398 * @see java.lang.Integer#parseInt(java.lang.String, int)
1399 */
1400 public static Integer decode(String nm) throws NumberFormatException {
1401 int radix = 10;
1402 int index = 0;
1403 boolean negative = false;
1404 Integer result;
1405
1406 if (nm.isEmpty())
1407 throw new NumberFormatException("Zero length string");
1408 char firstChar = nm.charAt(0);
1409 // Handle sign, if present
1410 if (firstChar == '-') {
1411 negative = true;
1412 index++;
1413 } else if (firstChar == '+')
1414 index++;
1415
1416 // Handle radix specifier, if present
1417 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1418 index += 2;
1419 radix = 16;
1420 }
1421 else if (nm.startsWith("#", index)) {
1422 index ++;
1423 radix = 16;
1424 }
1425 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1426 index ++;
1427 radix = 8;
1428 }
1429
1430 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1431 throw new NumberFormatException("Sign character in wrong position");
1432
1433 try {
1434 result = Integer.valueOf(nm.substring(index), radix);
1435 result = negative ? Integer.valueOf(-result.intValue()) : result;
1436 } catch (NumberFormatException e) {
1437 // If number is Integer.MIN_VALUE, we'll end up here. The next line
1438 // handles this case, and causes any genuine format error to be
1439 // rethrown.
1440 String constant = negative ? ("-" + nm.substring(index))
1441 : nm.substring(index);
1442 result = Integer.valueOf(constant, radix);
1443 }
1444 return result;
1445 }
1446
1447 /**
1448 * Compares two {@code Integer} objects numerically.
1449 *
1450 * @param anotherInteger the {@code Integer} to be compared.
1451 * @return the value {@code 0} if this {@code Integer} is
1452 * equal to the argument {@code Integer}; a value less than
1453 * {@code 0} if this {@code Integer} is numerically less
1454 * than the argument {@code Integer}; and a value greater
1455 * than {@code 0} if this {@code Integer} is numerically
1456 * greater than the argument {@code Integer} (signed
1457 * comparison).
1458 * @since 1.2
1459 */
1460 public int compareTo(Integer anotherInteger) {
1461 return compare(this.value, anotherInteger.value);
1462 }
1463
1464 /**
1465 * Compares two {@code int} values numerically.
1466 * The value returned is identical to what would be returned by:
1467 * <pre>
1468 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1469 * </pre>
1470 *
1471 * @param x the first {@code int} to compare
1472 * @param y the second {@code int} to compare
1473 * @return the value {@code 0} if {@code x == y};
1474 * a value less than {@code 0} if {@code x < y}; and
1475 * a value greater than {@code 0} if {@code x > y}
1476 * @since 1.7
1477 */
1478 public static int compare(int x, int y) {
1479 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1480 }
1481
1482 /**
1483 * Compares two {@code int} values numerically treating the values
1484 * as unsigned.
1485 *
1486 * @param x the first {@code int} to compare
1487 * @param y the second {@code int} to compare
1488 * @return the value {@code 0} if {@code x == y}; a value less
1489 * than {@code 0} if {@code x < y} as unsigned values; and
1490 * a value greater than {@code 0} if {@code x > y} as
1491 * unsigned values
1492 * @since 1.8
1493 */
1494 public static int compareUnsigned(int x, int y) {
1495 return compare(x + MIN_VALUE, y + MIN_VALUE);
1496 }
1497
1498 /**
1499 * Converts the argument to a {@code long} by an unsigned
1500 * conversion. In an unsigned conversion to a {@code long}, the
1501 * high-order 32 bits of the {@code long} are zero and the
1502 * low-order 32 bits are equal to the bits of the integer
1503 * argument.
1504 *
1505 * Consequently, zero and positive {@code int} values are mapped
1506 * to a numerically equal {@code long} value and negative {@code
1507 * int} values are mapped to a {@code long} value equal to the
1508 * input plus 2<sup>32</sup>.
1509 *
1510 * @param x the value to convert to an unsigned {@code long}
1511 * @return the argument converted to {@code long} by an unsigned
1512 * conversion
1513 * @since 1.8
1514 */
1515 public static long toUnsignedLong(int x) {
1516 return ((long) x) & 0xffffffffL;
1517 }
1518
1519 /**
1520 * Returns the unsigned quotient of dividing the first argument by
1521 * the second where each argument and the result is interpreted as
1522 * an unsigned value.
1523 *
1524 * <p>Note that in two's complement arithmetic, the three other
1525 * basic arithmetic operations of add, subtract, and multiply are
1526 * bit-wise identical if the two operands are regarded as both
1527 * being signed or both being unsigned. Therefore separate {@code
1528 * addUnsigned}, etc. methods are not provided.
1529 *
1530 * @param dividend the value to be divided
1531 * @param divisor the value doing the dividing
1532 * @return the unsigned quotient of the first argument divided by
1533 * the second argument
1534 * @see #remainderUnsigned
1535 * @since 1.8
1536 */
1537 public static int divideUnsigned(int dividend, int divisor) {
1538 // In lieu of tricky code, for now just use long arithmetic.
1539 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor));
1540 }
1541
1542 /**
1543 * Returns the unsigned remainder from dividing the first argument
1544 * by the second where each argument and the result is interpreted
1545 * as an unsigned value.
1546 *
1547 * @param dividend the value to be divided
1548 * @param divisor the value doing the dividing
1549 * @return the unsigned remainder of the first argument divided by
1550 * the second argument
1551 * @see #divideUnsigned
1552 * @since 1.8
1553 */
1554 public static int remainderUnsigned(int dividend, int divisor) {
1555 // In lieu of tricky code, for now just use long arithmetic.
1556 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor));
1557 }
1558
1559
1560 // Bit twiddling
1561
1562 /**
1563 * The number of bits used to represent an {@code int} value in two's
1564 * complement binary form.
1565 *
1566 * @since 1.5
1567 */
1568 @Native public static final int SIZE = 32;
1569
1570 /**
1571 * The number of bytes used to represent an {@code int} value in two's
1572 * complement binary form.
1573 *
1574 * @since 1.8
1575 */
1576 public static final int BYTES = SIZE / Byte.SIZE;
1577
1578 /**
1579 * Returns an {@code int} value with at most a single one-bit, in the
1580 * position of the highest-order ("leftmost") one-bit in the specified
1581 * {@code int} value. Returns zero if the specified value has no
1582 * one-bits in its two's complement binary representation, that is, if it
1583 * is equal to zero.
1584 *
1585 * @param i the value whose highest one bit is to be computed
1586 * @return an {@code int} value with a single one-bit, in the position
1587 * of the highest-order one-bit in the specified value, or zero if
1588 * the specified value is itself equal to zero.
1589 * @since 1.5
1590 */
1591 public static int highestOneBit(int i) {
1592 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1593 }
1594
1595 /**
1596 * Returns an {@code int} value with at most a single one-bit, in the
1597 * position of the lowest-order ("rightmost") one-bit in the specified
1598 * {@code int} value. Returns zero if the specified value has no
1599 * one-bits in its two's complement binary representation, that is, if it
1600 * is equal to zero.
1601 *
1602 * @param i the value whose lowest one bit is to be computed
1603 * @return an {@code int} value with a single one-bit, in the position
1604 * of the lowest-order one-bit in the specified value, or zero if
1605 * the specified value is itself equal to zero.
1606 * @since 1.5
1607 */
1608 public static int lowestOneBit(int i) {
1609 // HD, Section 2-1
1610 return i & -i;
1611 }
1612
1613 /**
1614 * Returns the number of zero bits preceding the highest-order
1615 * ("leftmost") one-bit in the two's complement binary representation
1616 * of the specified {@code int} value. Returns 32 if the
1617 * specified value has no one-bits in its two's complement representation,
1618 * in other words if it is equal to zero.
1619 *
1620 * <p>Note that this method is closely related to the logarithm base 2.
1621 * For all positive {@code int} values x:
1622 * <ul>
1623 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1624 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1625 * </ul>
1626 *
1627 * @param i the value whose number of leading zeros is to be computed
1628 * @return the number of zero bits preceding the highest-order
1629 * ("leftmost") one-bit in the two's complement binary representation
1630 * of the specified {@code int} value, or 32 if the value
1631 * is equal to zero.
1632 * @since 1.5
1633 */
1634 @HotSpotIntrinsicCandidate
1635 public static int numberOfLeadingZeros(int i) {
1636 // HD, Count leading 0's
1637 if (i <= 0)
1638 return i == 0 ? 32 : 0;
1639 int n = 31;
1640 if (i >= 1 << 16) { n -= 16; i >>>= 16; }
1641 if (i >= 1 << 8) { n -= 8; i >>>= 8; }
1642 if (i >= 1 << 4) { n -= 4; i >>>= 4; }
1643 if (i >= 1 << 2) { n -= 2; i >>>= 2; }
1644 return n - (i >>> 1);
1645 }
1646
1647 /**
1648 * Returns the number of zero bits following the lowest-order ("rightmost")
1649 * one-bit in the two's complement binary representation of the specified
1650 * {@code int} value. Returns 32 if the specified value has no
1651 * one-bits in its two's complement representation, in other words if it is
1652 * equal to zero.
1653 *
1654 * @param i the value whose number of trailing zeros is to be computed
1655 * @return the number of zero bits following the lowest-order ("rightmost")
1656 * one-bit in the two's complement binary representation of the
1657 * specified {@code int} value, or 32 if the value is equal
1658 * to zero.
1659 * @since 1.5
1660 */
1661 @HotSpotIntrinsicCandidate
1662 public static int numberOfTrailingZeros(int i) {
1663 // HD, Count trailing 0's
1664 i = ~i & (i - 1);
1665 if (i <= 0) return i & 32;
1666 int n = 1;
1667 if (i > 1 << 16) { n += 16; i >>>= 16; }
1668 if (i > 1 << 8) { n += 8; i >>>= 8; }
1669 if (i > 1 << 4) { n += 4; i >>>= 4; }
1670 if (i > 1 << 2) { n += 2; i >>>= 2; }
1671 return n + (i >>> 1);
1672 }
1673
1674 /**
1675 * Returns the number of one-bits in the two's complement binary
1676 * representation of the specified {@code int} value. This function is
1677 * sometimes referred to as the <i>population count</i>.
1678 *
1679 * @param i the value whose bits are to be counted
1680 * @return the number of one-bits in the two's complement binary
1681 * representation of the specified {@code int} value.
1682 * @since 1.5
1683 */
1684 @HotSpotIntrinsicCandidate
1685 public static int bitCount(int i) {
1686 // HD, Figure 5-2
1687 i = i - ((i >>> 1) & 0x55555555);
1688 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1689 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1690 i = i + (i >>> 8);
1691 i = i + (i >>> 16);
1692 return i & 0x3f;
1693 }
1694
1695 /**
1696 * Returns the value obtained by rotating the two's complement binary
1697 * representation of the specified {@code int} value left by the
1698 * specified number of bits. (Bits shifted out of the left hand, or
1699 * high-order, side reenter on the right, or low-order.)
1700 *
1701 * <p>Note that left rotation with a negative distance is equivalent to
1702 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1703 * distance)}. Note also that rotation by any multiple of 32 is a
1704 * no-op, so all but the last five bits of the rotation distance can be
1705 * ignored, even if the distance is negative: {@code rotateLeft(val,
1706 * distance) == rotateLeft(val, distance & 0x1F)}.
1707 *
1708 * @param i the value whose bits are to be rotated left
1709 * @param distance the number of bit positions to rotate left
1710 * @return the value obtained by rotating the two's complement binary
1711 * representation of the specified {@code int} value left by the
1712 * specified number of bits.
1713 * @since 1.5
1714 */
1715 public static int rotateLeft(int i, int distance) {
1716 return (i << distance) | (i >>> -distance);
1717 }
1718
1719 /**
1720 * Returns the value obtained by rotating the two's complement binary
1721 * representation of the specified {@code int} value right by the
1722 * specified number of bits. (Bits shifted out of the right hand, or
1723 * low-order, side reenter on the left, or high-order.)
1724 *
1725 * <p>Note that right rotation with a negative distance is equivalent to
1726 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1727 * distance)}. Note also that rotation by any multiple of 32 is a
1728 * no-op, so all but the last five bits of the rotation distance can be
1729 * ignored, even if the distance is negative: {@code rotateRight(val,
1730 * distance) == rotateRight(val, distance & 0x1F)}.
1731 *
1732 * @param i the value whose bits are to be rotated right
1733 * @param distance the number of bit positions to rotate right
1734 * @return the value obtained by rotating the two's complement binary
1735 * representation of the specified {@code int} value right by the
1736 * specified number of bits.
1737 * @since 1.5
1738 */
1739 public static int rotateRight(int i, int distance) {
1740 return (i >>> distance) | (i << -distance);
1741 }
1742
1743 /**
1744 * Returns the value obtained by reversing the order of the bits in the
1745 * two's complement binary representation of the specified {@code int}
1746 * value.
1747 *
1748 * @param i the value to be reversed
1749 * @return the value obtained by reversing order of the bits in the
1750 * specified {@code int} value.
1751 * @since 1.5
1752 */
1753 public static int reverse(int i) {
1754 // HD, Figure 7-1
1755 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1756 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1757 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1758
1759 return reverseBytes(i);
1760 }
1761
1762 /**
1763 * Returns the signum function of the specified {@code int} value. (The
1764 * return value is -1 if the specified value is negative; 0 if the
1765 * specified value is zero; and 1 if the specified value is positive.)
1766 *
1767 * @param i the value whose signum is to be computed
1768 * @return the signum function of the specified {@code int} value.
1769 * @since 1.5
1770 */
1771 public static int signum(int i) {
1772 // HD, Section 2-7
1773 return (i >> 31) | (-i >>> 31);
1774 }
1775
1776 /**
1777 * Returns the value obtained by reversing the order of the bytes in the
1778 * two's complement representation of the specified {@code int} value.
1779 *
1780 * @param i the value whose bytes are to be reversed
1781 * @return the value obtained by reversing the bytes in the specified
1782 * {@code int} value.
1783 * @since 1.5
1784 */
1785 @HotSpotIntrinsicCandidate
1786 public static int reverseBytes(int i) {
1787 return (i << 24) |
1788 ((i & 0xff00) << 8) |
1789 ((i >>> 8) & 0xff00) |
1790 (i >>> 24);
1791 }
1792
1793 /**
1794 * Adds two integers together as per the + operator.
1795 *
1796 * @param a the first operand
1797 * @param b the second operand
1798 * @return the sum of {@code a} and {@code b}
1799 * @see java.util.function.BinaryOperator
1800 * @since 1.8
1801 */
1802 public static int sum(int a, int b) {
1803 return a + b;
1804 }
1805
1806 /**
1807 * Returns the greater of two {@code int} values
1808 * as if by calling {@link Math#max(int, int) Math.max}.
1809 *
1810 * @param a the first operand
1811 * @param b the second operand
1812 * @return the greater of {@code a} and {@code b}
1813 * @see java.util.function.BinaryOperator
1814 * @since 1.8
1815 */
1816 public static int max(int a, int b) {
1817 return Math.max(a, b);
1818 }
1819
1820 /**
1821 * Returns the smaller of two {@code int} values
1822 * as if by calling {@link Math#min(int, int) Math.min}.
1823 *
1824 * @param a the first operand
1825 * @param b the second operand
1826 * @return the smaller of {@code a} and {@code b}
1827 * @see java.util.function.BinaryOperator
1828 * @since 1.8
1829 */
1830 public static int min(int a, int b) {
1831 return Math.min(a, b);
1832 }
1833
1834 /**
1835 * Returns an {@link Optional} containing the nominal descriptor for this
1836 * instance, which is the instance itself.
1837 *
1838 * @return an {@link Optional} describing the {@linkplain Integer} instance
1839 * @since 12
1840 */
1841 @Override
1842 public Optional<Integer> describeConstable() {
1843 return Optional.of(this);
1844 }
1845
1846 /**
1847 * Resolves this instance as a {@link ConstantDesc}, the result of which is
1848 * the instance itself.
1849 *
1850 * @param lookup ignored
1851 * @return the {@linkplain Integer} instance
1852 * @since 12
1853 */
1854 @Override
1855 public Integer resolveConstantDesc(MethodHandles.Lookup lookup) {
1856 return this;
1857 }
1858
1859 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1860 @java.io.Serial
1861 @Native private static final long serialVersionUID = 1360826667806852920L;
1862 }