1 /*
2 * Copyright (c) 1994, 2013, 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.util.Objects;
30 import jdk.internal.HotSpotIntrinsicCandidate;
31
32 import static java.lang.String.COMPACT_STRINGS;
33 import static java.lang.String.LATIN1;
34 import static java.lang.String.UTF16;
35
36 /**
37 * The {@code Integer} class wraps a value of the primitive type
38 * {@code int} in an object. An object of type {@code Integer}
39 * contains a single field whose type is {@code int}.
40 *
41 * <p>In addition, this class provides several methods for converting
42 * an {@code int} to a {@code String} and a {@code String} to an
43 * {@code int}, as well as other constants and methods useful when
44 * dealing with an {@code int}.
45 *
46 * <p>Implementation note: The implementations of the "bit twiddling"
47 * methods (such as {@link #highestOneBit(int) highestOneBit} and
48 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
49 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
50 * Delight</i>, (Addison Wesley, 2002).
51 *
52 * @author Lee Boynton
53 * @author Arthur van Hoff
54 * @author Josh Bloch
55 * @author Joseph D. Darcy
56 * @since 1.0
57 */
58 public final class Integer extends Number implements Comparable<Integer> {
59 /**
60 * A constant holding the minimum value an {@code int} can
61 * have, -2<sup>31</sup>.
62 */
63 @Native public static final int MIN_VALUE = 0x80000000;
64
65 /**
66 * A constant holding the maximum value an {@code int} can
67 * have, 2<sup>31</sup>-1.
68 */
69 @Native public static final int MAX_VALUE = 0x7fffffff;
70
71 /**
72 * The {@code Class} instance representing the primitive type
73 * {@code int}.
74 *
75 * @since 1.1
76 */
77 @SuppressWarnings("unchecked")
78 public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
79
80 /**
81 * All possible chars for representing a number as a String
82 */
83 static final char[] digits = {
84 '0' , '1' , '2' , '3' , '4' , '5' ,
85 '6' , '7' , '8' , '9' , 'a' , 'b' ,
86 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
87 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
88 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
89 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
90 };
91
92 /**
93 * Returns a string representation of the first argument in the
94 * radix specified by the second argument.
95 *
96 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
97 * or larger than {@code Character.MAX_RADIX}, then the radix
98 * {@code 10} is used instead.
99 *
100 * <p>If the first argument is negative, the first element of the
101 * result is the ASCII minus character {@code '-'}
102 * ({@code '\u005Cu002D'}). If the first argument is not
103 * negative, no sign character appears in the result.
104 *
105 * <p>The remaining characters of the result represent the magnitude
106 * of the first argument. If the magnitude is zero, it is
107 * represented by a single zero character {@code '0'}
108 * ({@code '\u005Cu0030'}); otherwise, the first character of
109 * the representation of the magnitude will not be the zero
110 * character. The following ASCII characters are used as digits:
111 *
112 * <blockquote>
113 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
114 * </blockquote>
115 *
116 * These are {@code '\u005Cu0030'} through
117 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
118 * {@code '\u005Cu007A'}. If {@code radix} is
119 * <var>N</var>, then the first <var>N</var> of these characters
120 * are used as radix-<var>N</var> digits in the order shown. Thus,
121 * the digits for hexadecimal (radix 16) are
122 * {@code 0123456789abcdef}. If uppercase letters are
123 * desired, the {@link java.lang.String#toUpperCase()} method may
124 * be called on the result:
125 *
126 * <blockquote>
127 * {@code Integer.toString(n, 16).toUpperCase()}
128 * </blockquote>
129 *
130 * @param i an integer to be converted to a string.
131 * @param radix the radix to use in the string representation.
132 * @return a string representation of the argument in the specified radix.
133 * @see java.lang.Character#MAX_RADIX
134 * @see java.lang.Character#MIN_RADIX
135 */
136 public static String toString(int i, int radix) {
137 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
138 radix = 10;
139
140 /* Use the faster version */
141 if (radix == 10) {
142 return toString(i);
143 }
144
145 if (COMPACT_STRINGS) {
146 byte[] buf = new byte[33];
147 boolean negative = (i < 0);
148 int charPos = 32;
149
150 if (!negative) {
151 i = -i;
152 }
153
154 while (i <= -radix) {
155 buf[charPos--] = (byte)digits[-(i % radix)];
156 i = i / radix;
157 }
158 buf[charPos] = (byte)digits[-i];
159
160 if (negative) {
161 buf[--charPos] = '-';
162 }
163
164 return StringLatin1.newString(buf, charPos, (33 - charPos));
165 }
166 return toStringUTF16(i, radix);
167 }
168
169 private static String toStringUTF16(int i, int radix) {
170 byte[] buf = new byte[33 * 2];
171 boolean negative = (i < 0);
172 int charPos = 32;
173 if (!negative) {
174 i = -i;
175 }
176 while (i <= -radix) {
177 StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
178 i = i / radix;
179 }
180 StringUTF16.putChar(buf, charPos, digits[-i]);
181
182 if (negative) {
183 StringUTF16.putChar(buf, --charPos, '-');
184 }
185 return StringUTF16.newString(buf, charPos, (33 - charPos));
186 }
187
188 /**
189 * Returns a string representation of the first argument as an
190 * unsigned integer value in the radix specified by the second
191 * argument.
192 *
193 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
194 * or larger than {@code Character.MAX_RADIX}, then the radix
195 * {@code 10} is used instead.
196 *
197 * <p>Note that since the first argument is treated as an unsigned
198 * value, no leading sign character is printed.
199 *
200 * <p>If the magnitude is zero, it is represented by a single zero
201 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
202 * the first character of the representation of the magnitude will
203 * not be the zero character.
204 *
205 * <p>The behavior of radixes and the characters used as digits
206 * are the same as {@link #toString(int, int) toString}.
207 *
208 * @param i an integer to be converted to an unsigned string.
209 * @param radix the radix to use in the string representation.
210 * @return an unsigned string representation of the argument in the specified radix.
211 * @see #toString(int, int)
212 * @since 1.8
213 */
214 public static String toUnsignedString(int i, int radix) {
215 return Long.toUnsignedString(toUnsignedLong(i), radix);
216 }
217
218 /**
219 * Returns a string representation of the integer argument as an
220 * unsigned integer in base 16.
221 *
222 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
223 * if the argument is negative; otherwise, it is equal to the
224 * argument. This value is converted to a string of ASCII digits
225 * in hexadecimal (base 16) with no extra leading
226 * {@code 0}s.
227 *
228 * <p>The value of the argument can be recovered from the returned
229 * string {@code s} by calling {@link
230 * Integer#parseUnsignedInt(String, int)
231 * Integer.parseUnsignedInt(s, 16)}.
232 *
233 * <p>If the unsigned magnitude is zero, it is represented by a
234 * single zero character {@code '0'} ({@code '\u005Cu0030'});
235 * otherwise, the first character of the representation of the
236 * unsigned magnitude will not be the zero character. The
237 * following characters are used as hexadecimal digits:
238 *
239 * <blockquote>
240 * {@code 0123456789abcdef}
241 * </blockquote>
242 *
243 * These are the characters {@code '\u005Cu0030'} through
244 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
245 * {@code '\u005Cu0066'}. If uppercase letters are
246 * desired, the {@link java.lang.String#toUpperCase()} method may
247 * be called on the result:
248 *
249 * <blockquote>
250 * {@code Integer.toHexString(n).toUpperCase()}
251 * </blockquote>
252 *
253 * @param i an integer to be converted to a string.
254 * @return the string representation of the unsigned integer value
255 * represented by the argument in hexadecimal (base 16).
256 * @see #parseUnsignedInt(String, int)
257 * @see #toUnsignedString(int, int)
258 * @since 1.0.2
259 */
260 public static String toHexString(int i) {
261 return toUnsignedString0(i, 4);
262 }
263
264 /**
265 * Returns a string representation of the integer argument as an
266 * unsigned integer in base 8.
267 *
268 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
269 * if the argument is negative; otherwise, it is equal to the
270 * argument. This value is converted to a string of ASCII digits
271 * in octal (base 8) with no extra leading {@code 0}s.
272 *
273 * <p>The value of the argument can be recovered from the returned
274 * string {@code s} by calling {@link
275 * Integer#parseUnsignedInt(String, int)
276 * Integer.parseUnsignedInt(s, 8)}.
277 *
278 * <p>If the unsigned magnitude is zero, it is represented by a
279 * single zero character {@code '0'} ({@code '\u005Cu0030'});
280 * otherwise, the first character of the representation of the
281 * unsigned magnitude will not be the zero character. The
282 * following characters are used as octal digits:
283 *
284 * <blockquote>
285 * {@code 01234567}
286 * </blockquote>
287 *
288 * These are the characters {@code '\u005Cu0030'} through
289 * {@code '\u005Cu0037'}.
290 *
291 * @param i an integer to be converted to a string.
292 * @return the string representation of the unsigned integer value
293 * represented by the argument in octal (base 8).
294 * @see #parseUnsignedInt(String, int)
295 * @see #toUnsignedString(int, int)
296 * @since 1.0.2
297 */
298 public static String toOctalString(int i) {
299 return toUnsignedString0(i, 3);
300 }
301
302 /**
303 * Returns a string representation of the integer argument as an
304 * unsigned integer in base 2.
305 *
306 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
307 * if the argument is negative; otherwise it is equal to the
308 * argument. This value is converted to a string of ASCII digits
309 * in binary (base 2) with no extra leading {@code 0}s.
310 *
311 * <p>The value of the argument can be recovered from the returned
312 * string {@code s} by calling {@link
313 * Integer#parseUnsignedInt(String, int)
314 * Integer.parseUnsignedInt(s, 2)}.
315 *
316 * <p>If the unsigned magnitude is zero, it is represented by a
317 * single zero character {@code '0'} ({@code '\u005Cu0030'});
318 * otherwise, the first character of the representation of the
319 * unsigned magnitude will not be the zero character. The
320 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
321 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
322 *
323 * @param i an integer to be converted to a string.
324 * @return the string representation of the unsigned integer value
325 * represented by the argument in binary (base 2).
326 * @see #parseUnsignedInt(String, int)
327 * @see #toUnsignedString(int, int)
328 * @since 1.0.2
329 */
330 public static String toBinaryString(int i) {
331 return toUnsignedString0(i, 1);
332 }
333
334 /**
335 * Convert the integer to an unsigned number.
336 */
337 private static String toUnsignedString0(int val, int shift) {
338 // assert shift > 0 && shift <=5 : "Illegal shift value";
339 int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
340 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
341 if (COMPACT_STRINGS) {
342 byte[] buf = new byte[chars];
343 formatUnsignedInt(val, shift, buf, 0, chars);
344 return new String(buf, LATIN1);
345 } else {
346 byte[] buf = new byte[chars * 2];
347 formatUnsignedIntUTF16(val, shift, buf, 0, chars);
348 return new String(buf, UTF16);
349 }
350 }
351
352 /**
353 * Format an {@code int} (treated as unsigned) into a character buffer. If
354 * {@code len} exceeds the formatted ASCII representation of {@code val},
355 * {@code buf} will be padded with leading zeroes.
356 *
357 * @param val the unsigned int to format
358 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
359 * @param buf the character buffer to write to
360 * @param offset the offset in the destination buffer to start at
361 * @param len the number of characters to write
362 */
363 static void formatUnsignedInt(int val, int shift, char[] buf, int offset, int len) {
364 // assert shift > 0 && shift <=5 : "Illegal shift value";
365 // assert offset >= 0 && offset < buf.length : "illegal offset";
366 // assert len > 0 && (offset + len) <= buf.length : "illegal length";
367 int charPos = offset + len;
368 int radix = 1 << shift;
369 int mask = radix - 1;
370 do {
371 buf[--charPos] = Integer.digits[val & mask];
372 val >>>= shift;
373 } while (charPos > offset);
374 }
375
376 /** byte[]/LATIN1 version */
377 static void formatUnsignedInt(int val, int shift, byte[] buf, int offset, int len) {
378 int charPos = offset + len;
379 int radix = 1 << shift;
380 int mask = radix - 1;
381 do {
382 buf[--charPos] = (byte)Integer.digits[val & mask];
383 val >>>= shift;
384 } while (charPos > offset);
385 }
386
387 /** byte[]/UTF16 version */
388 static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int offset, int len) {
389 int charPos = offset + len;
390 int radix = 1 << shift;
391 int mask = radix - 1;
392 do {
393 StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
394 val >>>= shift;
395 } while (charPos > offset);
396 }
397
398 static final byte[] DigitTens = {
399 '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
400 '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
401 '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
402 '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
403 '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
404 '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
405 '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
406 '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
407 '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
408 '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
409 } ;
410
411 static final byte[] DigitOnes = {
412 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
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 } ;
423
424
425 /**
426 * Returns a {@code String} object representing the
427 * specified integer. The argument is converted to signed decimal
428 * representation and returned as a string, exactly as if the
429 * argument and radix 10 were given as arguments to the {@link
430 * #toString(int, int)} method.
431 *
432 * @param i an integer to be converted.
433 * @return a string representation of the argument in base 10.
434 */
435 @HotSpotIntrinsicCandidate
436 public static String toString(int i) {
437 int size = stringSize(i);
438 if (COMPACT_STRINGS) {
439 byte[] buf = new byte[size];
440 getChars(i, size, buf);
441 return new String(buf, LATIN1);
442 } else {
443 byte[] buf = new byte[size * 2];
444 getCharsUTF16(i, size, buf);
445 return new String(buf, UTF16);
446 }
447 }
448
449 /**
450 * Returns a string representation of the argument as an unsigned
451 * decimal value.
452 *
453 * The argument is converted to unsigned decimal representation
454 * and returned as a string exactly as if the argument and radix
455 * 10 were given as arguments to the {@link #toUnsignedString(int,
456 * int)} method.
457 *
458 * @param i an integer to be converted to an unsigned string.
459 * @return an unsigned string representation of the argument.
460 * @see #toUnsignedString(int, int)
461 * @since 1.8
462 */
463 public static String toUnsignedString(int i) {
464 return Long.toString(toUnsignedLong(i));
465 }
466
467 /**
468 * Places characters representing the integer i into the
469 * character array buf. The characters are placed into
470 * the buffer backwards starting with the least significant
471 * digit at the specified index (exclusive), and working
472 * backwards from there.
473 *
474 * @implNote This method converts positive inputs into negative
475 * values, to cover the Integer.MIN_VALUE case. Converting otherwise
476 * (negative to positive) will expose -Integer.MIN_VALUE that overflows
477 * integer.
478 *
479 * @param i value to convert
480 * @param index next index, after the least significant digit
481 * @param buf target buffer, Latin1-encoded
482 * @return index of the most significant digit or minus sign, if present
483 */
484 static int getChars(int i, int index, byte[] buf) {
485 int q, r;
486 int charPos = index;
487
488 boolean negative = i < 0;
489 if (!negative) {
490 i = -i;
491 }
492
493 // Generate two digits per iteration
494 while (i <= -100) {
495 q = i / 100;
496 r = (q * 100) - i;
497 i = q;
498 buf[--charPos] = DigitOnes[r];
499 buf[--charPos] = DigitTens[r];
500 }
501
502 // We know there are at most two digits left at this point.
503 q = i / 10;
504 r = (q * 10) - i;
505 buf[--charPos] = (byte)('0' + r);
506
507 // Whatever left is the remaining digit.
508 if (q < 0) {
509 buf[--charPos] = (byte)('0' - q);
510 }
511
512 if (negative) {
513 buf[--charPos] = (byte)'-';
514 }
515 return charPos;
516 }
517
518 /**
519 * This is a variant of {@link #getChars(int, int, byte[])}, but for
520 * UTF-16 coder.
521 *
522 * @param i value to convert
523 * @param index next index, after the least significant digit
524 * @param buf target buffer, UTF16-coded.
525 * @return index of the most significant digit or minus sign, if present
526 */
527 static int getCharsUTF16(int i, int index, byte[] buf) {
528 int q, r;
529 int charPos = index;
530
531 boolean negative = (i < 0);
532 if (!negative) {
533 i = -i;
534 }
535
536 // Get 2 digits/iteration using ints
537 while (i <= -100) {
538 q = i / 100;
539 r = (q * 100) - i;
540 i = q;
541 StringUTF16.putChar(buf, --charPos, DigitOnes[r]);
542 StringUTF16.putChar(buf, --charPos, DigitTens[r]);
543 }
544
545 // We know there are at most two digits left at this point.
546 q = i / 10;
547 r = (q * 10) - i;
548 StringUTF16.putChar(buf, --charPos, '0' + r);
549
550 // Whatever left is the remaining digit.
551 if (q < 0) {
552 StringUTF16.putChar(buf, --charPos, '0' - q);
553 }
554
555 if (negative) {
556 StringUTF16.putChar(buf, --charPos, '-');
557 }
558 return charPos;
559 }
560
561 // Left here for compatibility reasons, see JDK-8143900.
562 static final int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
563 99999999, 999999999, Integer.MAX_VALUE };
564
565 /**
566 * Returns the string representation size for a given int value.
567 *
568 * @param x int value
569 * @return string size
570 *
571 * @implNote There are other ways to compute this: e.g. binary search,
572 * but values are biased heavily towards zero, and therefore linear search
573 * wins. The iteration results are also routinely inlined in the generated
574 * code after loop unrolling.
575 */
576 static int stringSize(int x) {
577 int d = 1;
578 if (x >= 0) {
579 d = 0;
580 x = -x;
581 }
582 int p = -10;
583 for (int i = 1; i < 10; i++) {
584 if (x > p)
585 return i + d;
586 p = 10 * p;
587 }
588 return 10 + d;
589 }
590
591 /**
592 * Parses the string argument as a signed integer in the radix
593 * specified by the second argument. The characters in the string
594 * must all be digits of the specified radix (as determined by
595 * whether {@link java.lang.Character#digit(char, int)} returns a
596 * nonnegative value), except that the first character may be an
597 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
598 * indicate a negative value or an ASCII plus sign {@code '+'}
599 * ({@code '\u005Cu002B'}) to indicate a positive value. The
600 * resulting integer value is returned.
601 *
602 * <p>An exception of type {@code NumberFormatException} is
603 * thrown if any of the following situations occurs:
604 * <ul>
605 * <li>The first argument is {@code null} or is a string of
606 * length zero.
607 *
608 * <li>The radix is either smaller than
609 * {@link java.lang.Character#MIN_RADIX} or
610 * larger than {@link java.lang.Character#MAX_RADIX}.
611 *
612 * <li>Any character of the string is not a digit of the specified
613 * radix, except that the first character may be a minus sign
614 * {@code '-'} ({@code '\u005Cu002D'}) or plus sign
615 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
616 * string is longer than length 1.
617 *
618 * <li>The value represented by the string is not a value of type
619 * {@code int}.
620 * </ul>
621 *
622 * <p>Examples:
623 * <blockquote><pre>
624 * parseInt("0", 10) returns 0
625 * parseInt("473", 10) returns 473
626 * parseInt("+42", 10) returns 42
627 * parseInt("-0", 10) returns 0
628 * parseInt("-FF", 16) returns -255
629 * parseInt("1100110", 2) returns 102
630 * parseInt("2147483647", 10) returns 2147483647
631 * parseInt("-2147483648", 10) returns -2147483648
632 * parseInt("2147483648", 10) throws a NumberFormatException
633 * parseInt("99", 8) throws a NumberFormatException
634 * parseInt("Kona", 10) throws a NumberFormatException
635 * parseInt("Kona", 27) returns 411787
636 * </pre></blockquote>
637 *
638 * @param s the {@code String} containing the integer
639 * representation to be parsed
640 * @param radix the radix to be used while parsing {@code s}.
641 * @return the integer represented by the string argument in the
642 * specified radix.
643 * @exception NumberFormatException if the {@code String}
644 * does not contain a parsable {@code int}.
645 */
646 public static int parseInt(String s, int radix)
647 throws NumberFormatException
648 {
649 /*
650 * WARNING: This method may be invoked early during VM initialization
651 * before IntegerCache is initialized. Care must be taken to not use
652 * the valueOf method.
653 */
654
655 if (s == null) {
656 throw new NumberFormatException("null");
657 }
658
659 if (radix < Character.MIN_RADIX) {
660 throw new NumberFormatException("radix " + radix +
661 " less than Character.MIN_RADIX");
662 }
663
664 if (radix > Character.MAX_RADIX) {
665 throw new NumberFormatException("radix " + radix +
666 " greater than Character.MAX_RADIX");
667 }
668
669 boolean negative = false;
670 int i = 0, len = s.length();
671 int limit = -Integer.MAX_VALUE;
672
673 if (len > 0) {
674 char firstChar = s.charAt(0);
675 if (firstChar < '0') { // Possible leading "+" or "-"
676 if (firstChar == '-') {
677 negative = true;
678 limit = Integer.MIN_VALUE;
679 } else if (firstChar != '+') {
680 throw NumberFormatException.forInputString(s);
681 }
682
683 if (len == 1) { // Cannot have lone "+" or "-"
684 throw NumberFormatException.forInputString(s);
685 }
686 i++;
687 }
688 int multmin = limit / radix;
689 int result = 0;
690 while (i < len) {
691 // Accumulating negatively avoids surprises near MAX_VALUE
692 int digit = Character.digit(s.charAt(i++), radix);
693 if (digit < 0 || result < multmin) {
694 throw NumberFormatException.forInputString(s);
695 }
696 result *= radix;
697 if (result < limit + digit) {
698 throw NumberFormatException.forInputString(s);
699 }
700 result -= digit;
701 }
702 return negative ? result : -result;
703 } else {
704 throw NumberFormatException.forInputString(s);
705 }
706 }
707
708 /**
709 * Parses the {@link CharSequence} argument as a signed {@code int} in the
710 * specified {@code radix}, beginning at the specified {@code beginIndex}
711 * and extending to {@code endIndex - 1}.
712 *
713 * <p>The method does not take steps to guard against the
714 * {@code CharSequence} being mutated while parsing.
715 *
716 * @param s the {@code CharSequence} containing the {@code int}
717 * representation to be parsed
718 * @param beginIndex the beginning index, inclusive.
719 * @param endIndex the ending index, exclusive.
720 * @param radix the radix to be used while parsing {@code s}.
721 * @return the signed {@code int} represented by the subsequence in
722 * the specified radix.
723 * @throws NullPointerException if {@code s} is null.
724 * @throws IndexOutOfBoundsException if {@code beginIndex} is
725 * negative, or if {@code beginIndex} is greater than
726 * {@code endIndex} or if {@code endIndex} is greater than
727 * {@code s.length()}.
728 * @throws NumberFormatException if the {@code CharSequence} does not
729 * contain a parsable {@code int} in the specified
730 * {@code radix}, or if {@code radix} is either smaller than
731 * {@link java.lang.Character#MIN_RADIX} or larger than
732 * {@link java.lang.Character#MAX_RADIX}.
733 * @since 1.9
734 */
735 public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
736 throws NumberFormatException {
737 s = Objects.requireNonNull(s);
738
739 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
740 throw new IndexOutOfBoundsException();
741 }
742 if (radix < Character.MIN_RADIX) {
743 throw new NumberFormatException("radix " + radix +
744 " less than Character.MIN_RADIX");
745 }
746 if (radix > Character.MAX_RADIX) {
747 throw new NumberFormatException("radix " + radix +
748 " greater than Character.MAX_RADIX");
749 }
750
751 boolean negative = false;
752 int i = beginIndex;
753 int limit = -Integer.MAX_VALUE;
754
755 if (i < endIndex) {
756 char firstChar = s.charAt(i);
757 if (firstChar < '0') { // Possible leading "+" or "-"
758 if (firstChar == '-') {
759 negative = true;
760 limit = Integer.MIN_VALUE;
761 } else if (firstChar != '+') {
762 throw NumberFormatException.forCharSequence(s, beginIndex,
763 endIndex, i);
764 }
765 i++;
766 if (i == endIndex) { // Cannot have lone "+" or "-"
767 throw NumberFormatException.forCharSequence(s, beginIndex,
768 endIndex, i);
769 }
770 }
771 int multmin = limit / radix;
772 int result = 0;
773 while (i < endIndex) {
774 // Accumulating negatively avoids surprises near MAX_VALUE
775 int digit = Character.digit(s.charAt(i), radix);
776 if (digit < 0 || result < multmin) {
777 throw NumberFormatException.forCharSequence(s, beginIndex,
778 endIndex, i);
779 }
780 result *= radix;
781 if (result < limit + digit) {
782 throw NumberFormatException.forCharSequence(s, beginIndex,
783 endIndex, i);
784 }
785 i++;
786 result -= digit;
787 }
788 return negative ? result : -result;
789 } else {
790 throw NumberFormatException.forInputString("");
791 }
792 }
793
794 /**
795 * Parses the string argument as a signed decimal integer. The
796 * characters in the string must all be decimal digits, except
797 * that the first character may be an ASCII minus sign {@code '-'}
798 * ({@code '\u005Cu002D'}) to indicate a negative value or an
799 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
800 * indicate a positive value. The resulting integer value is
801 * returned, exactly as if the argument and the radix 10 were
802 * given as arguments to the {@link #parseInt(java.lang.String,
803 * int)} method.
804 *
805 * @param s a {@code String} containing the {@code int}
806 * representation to be parsed
807 * @return the integer value represented by the argument in decimal.
808 * @exception NumberFormatException if the string does not contain a
809 * parsable integer.
810 */
811 public static int parseInt(String s) throws NumberFormatException {
812 return parseInt(s,10);
813 }
814
815 /**
816 * Parses the string argument as an unsigned integer in the radix
817 * specified by the second argument. An unsigned integer maps the
818 * values usually associated with negative numbers to positive
819 * numbers larger than {@code MAX_VALUE}.
820 *
821 * The characters in the string must all be digits of the
822 * specified radix (as determined by whether {@link
823 * java.lang.Character#digit(char, int)} returns a nonnegative
824 * value), except that the first character may be an ASCII plus
825 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
826 * integer value is returned.
827 *
828 * <p>An exception of type {@code NumberFormatException} is
829 * thrown if any of the following situations occurs:
830 * <ul>
831 * <li>The first argument is {@code null} or is a string of
832 * length zero.
833 *
834 * <li>The radix is either smaller than
835 * {@link java.lang.Character#MIN_RADIX} or
836 * larger than {@link java.lang.Character#MAX_RADIX}.
837 *
838 * <li>Any character of the string is not a digit of the specified
839 * radix, except that the first character may be a plus sign
840 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
841 * string is longer than length 1.
842 *
843 * <li>The value represented by the string is larger than the
844 * largest unsigned {@code int}, 2<sup>32</sup>-1.
845 *
846 * </ul>
847 *
848 *
849 * @param s the {@code String} containing the unsigned integer
850 * representation to be parsed
851 * @param radix the radix to be used while parsing {@code s}.
852 * @return the integer represented by the string argument in the
853 * specified radix.
854 * @throws NumberFormatException if the {@code String}
855 * does not contain a parsable {@code int}.
856 * @since 1.8
857 */
858 public static int parseUnsignedInt(String s, int radix)
859 throws NumberFormatException {
860 if (s == null) {
861 throw new NumberFormatException("null");
862 }
863
864 int len = s.length();
865 if (len > 0) {
866 char firstChar = s.charAt(0);
867 if (firstChar == '-') {
868 throw new
869 NumberFormatException(String.format("Illegal leading minus sign " +
870 "on unsigned string %s.", s));
871 } else {
872 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
873 (radix == 10 && len <= 9) ) { // Integer.MAX_VALUE in base 10 is 10 digits
874 return parseInt(s, radix);
875 } else {
876 long ell = Long.parseLong(s, radix);
877 if ((ell & 0xffff_ffff_0000_0000L) == 0) {
878 return (int) ell;
879 } else {
880 throw new
881 NumberFormatException(String.format("String value %s exceeds " +
882 "range of unsigned int.", s));
883 }
884 }
885 }
886 } else {
887 throw NumberFormatException.forInputString(s);
888 }
889 }
890
891 /**
892 * Parses the {@link CharSequence} argument as an unsigned {@code int} in
893 * the specified {@code radix}, beginning at the specified
894 * {@code beginIndex} and extending to {@code endIndex - 1}.
895 *
896 * <p>The method does not take steps to guard against the
897 * {@code CharSequence} being mutated while parsing.
898 *
899 * @param s the {@code CharSequence} containing the unsigned
900 * {@code int} representation to be parsed
901 * @param beginIndex the beginning index, inclusive.
902 * @param endIndex the ending index, exclusive.
903 * @param radix the radix to be used while parsing {@code s}.
904 * @return the unsigned {@code int} represented by the subsequence in
905 * the specified radix.
906 * @throws NullPointerException if {@code s} is null.
907 * @throws IndexOutOfBoundsException if {@code beginIndex} is
908 * negative, or if {@code beginIndex} is greater than
909 * {@code endIndex} or if {@code endIndex} is greater than
910 * {@code s.length()}.
911 * @throws NumberFormatException if the {@code CharSequence} does not
912 * contain a parsable unsigned {@code int} in the specified
913 * {@code radix}, or if {@code radix} is either smaller than
914 * {@link java.lang.Character#MIN_RADIX} or larger than
915 * {@link java.lang.Character#MAX_RADIX}.
916 * @since 1.9
917 */
918 public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
919 throws NumberFormatException {
920 s = Objects.requireNonNull(s);
921
922 if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
923 throw new IndexOutOfBoundsException();
924 }
925 int start = beginIndex, len = endIndex - beginIndex;
926
927 if (len > 0) {
928 char firstChar = s.charAt(start);
929 if (firstChar == '-') {
930 throw new
931 NumberFormatException(String.format("Illegal leading minus sign " +
932 "on unsigned string %s.", s));
933 } else {
934 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
935 (radix == 10 && len <= 9)) { // Integer.MAX_VALUE in base 10 is 10 digits
936 return parseInt(s, start, start + len, radix);
937 } else {
938 long ell = Long.parseLong(s, start, start + len, radix);
939 if ((ell & 0xffff_ffff_0000_0000L) == 0) {
940 return (int) ell;
941 } else {
942 throw new
943 NumberFormatException(String.format("String value %s exceeds " +
944 "range of unsigned int.", s));
945 }
946 }
947 }
948 } else {
949 throw new NumberFormatException("");
950 }
951 }
952
953 /**
954 * Parses the string argument as an unsigned decimal integer. The
955 * characters in the string must all be decimal digits, except
956 * that the first character may be an ASCII plus sign {@code
957 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
958 * is returned, exactly as if the argument and the radix 10 were
959 * given as arguments to the {@link
960 * #parseUnsignedInt(java.lang.String, int)} method.
961 *
962 * @param s a {@code String} containing the unsigned {@code int}
963 * representation to be parsed
964 * @return the unsigned integer value represented by the argument in decimal.
965 * @throws NumberFormatException if the string does not contain a
966 * parsable unsigned integer.
967 * @since 1.8
968 */
969 public static int parseUnsignedInt(String s) throws NumberFormatException {
970 return parseUnsignedInt(s, 10);
971 }
972
973 /**
974 * Returns an {@code Integer} object holding the value
975 * extracted from the specified {@code String} when parsed
976 * with the radix given by the second argument. The first argument
977 * is interpreted as representing a signed integer in the radix
978 * specified by the second argument, exactly as if the arguments
979 * were given to the {@link #parseInt(java.lang.String, int)}
980 * method. The result is an {@code Integer} object that
981 * represents the integer value specified by the string.
982 *
983 * <p>In other words, this method returns an {@code Integer}
984 * object equal to the value of:
985 *
986 * <blockquote>
987 * {@code new Integer(Integer.parseInt(s, radix))}
988 * </blockquote>
989 *
990 * @param s the string to be parsed.
991 * @param radix the radix to be used in interpreting {@code s}
992 * @return an {@code Integer} object holding the value
993 * represented by the string argument in the specified
994 * radix.
995 * @exception NumberFormatException if the {@code String}
996 * does not contain a parsable {@code int}.
997 */
998 public static Integer valueOf(String s, int radix) throws NumberFormatException {
999 return Integer.valueOf(parseInt(s,radix));
1000 }
1001
1002 /**
1003 * Returns an {@code Integer} object holding the
1004 * value of the specified {@code String}. The argument is
1005 * interpreted as representing a signed decimal integer, exactly
1006 * as if the argument were given to the {@link
1007 * #parseInt(java.lang.String)} method. The result is an
1008 * {@code Integer} object that represents the integer value
1009 * specified by the string.
1010 *
1011 * <p>In other words, this method returns an {@code Integer}
1012 * object equal to the value of:
1013 *
1014 * <blockquote>
1015 * {@code new Integer(Integer.parseInt(s))}
1016 * </blockquote>
1017 *
1018 * @param s the string to be parsed.
1019 * @return an {@code Integer} object holding the value
1020 * represented by the string argument.
1021 * @exception NumberFormatException if the string cannot be parsed
1022 * as an integer.
1023 */
1024 public static Integer valueOf(String s) throws NumberFormatException {
1025 return Integer.valueOf(parseInt(s, 10));
1026 }
1027
1028 /**
1029 * Cache to support the object identity semantics of autoboxing for values between
1030 * -128 and 127 (inclusive) as required by JLS.
1031 *
1032 * The cache is initialized on first usage. The size of the cache
1033 * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
1034 * During VM initialization, java.lang.Integer.IntegerCache.high property
1035 * may be set and saved in the private system properties in the
1036 * sun.misc.VM class.
1037 */
1038
1039 private static class IntegerCache {
1040 static final int low = -128;
1041 static final int high;
1042 static final Integer cache[];
1043
1044 static {
1045 // high value may be configured by property
1046 int h = 127;
1047 String integerCacheHighPropValue =
1048 sun.misc.VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
1049 if (integerCacheHighPropValue != null) {
1050 try {
1051 int i = parseInt(integerCacheHighPropValue);
1052 i = Math.max(i, 127);
1053 // Maximum array size is Integer.MAX_VALUE
1054 h = Math.min(i, Integer.MAX_VALUE - (-low) -1);
1055 } catch( NumberFormatException nfe) {
1056 // If the property cannot be parsed into an int, ignore it.
1057 }
1058 }
1059 high = h;
1060
1061 cache = new Integer[(high - low) + 1];
1062 int j = low;
1063 for(int k = 0; k < cache.length; k++)
1064 cache[k] = new Integer(j++);
1065
1066 // range [-128, 127] must be interned (JLS7 5.1.7)
1067 assert IntegerCache.high >= 127;
1068 }
1069
1070 private IntegerCache() {}
1071 }
1072
1073 /**
1074 * Returns an {@code Integer} instance representing the specified
1075 * {@code int} value. If a new {@code Integer} instance is not
1076 * required, this method should generally be used in preference to
1077 * the constructor {@link #Integer(int)}, as this method is likely
1078 * to yield significantly better space and time performance by
1079 * caching frequently requested values.
1080 *
1081 * This method will always cache values in the range -128 to 127,
1082 * inclusive, and may cache other values outside of this range.
1083 *
1084 * @param i an {@code int} value.
1085 * @return an {@code Integer} instance representing {@code i}.
1086 * @since 1.5
1087 */
1088 @HotSpotIntrinsicCandidate
1089 public static Integer valueOf(int i) {
1090 if (i >= IntegerCache.low && i <= IntegerCache.high)
1091 return IntegerCache.cache[i + (-IntegerCache.low)];
1092 return new Integer(i);
1093 }
1094
1095 /**
1096 * The value of the {@code Integer}.
1097 *
1098 * @serial
1099 */
1100 private final int value;
1101
1102 /**
1103 * Constructs a newly allocated {@code Integer} object that
1104 * represents the specified {@code int} value.
1105 *
1106 * @param value the value to be represented by the
1107 * {@code Integer} object.
1108 */
1109 public Integer(int value) {
1110 this.value = value;
1111 }
1112
1113 /**
1114 * Constructs a newly allocated {@code Integer} object that
1115 * represents the {@code int} value indicated by the
1116 * {@code String} parameter. The string is converted to an
1117 * {@code int} value in exactly the manner used by the
1118 * {@code parseInt} method for radix 10.
1119 *
1120 * @param s the {@code String} to be converted to an
1121 * {@code Integer}.
1122 * @exception NumberFormatException if the {@code String} does not
1123 * contain a parsable integer.
1124 * @see java.lang.Integer#parseInt(java.lang.String, int)
1125 */
1126 public Integer(String s) throws NumberFormatException {
1127 this.value = parseInt(s, 10);
1128 }
1129
1130 /**
1131 * Returns the value of this {@code Integer} as a {@code byte}
1132 * after a narrowing primitive conversion.
1133 * @jls 5.1.3 Narrowing Primitive Conversions
1134 */
1135 public byte byteValue() {
1136 return (byte)value;
1137 }
1138
1139 /**
1140 * Returns the value of this {@code Integer} as a {@code short}
1141 * after a narrowing primitive conversion.
1142 * @jls 5.1.3 Narrowing Primitive Conversions
1143 */
1144 public short shortValue() {
1145 return (short)value;
1146 }
1147
1148 /**
1149 * Returns the value of this {@code Integer} as an
1150 * {@code int}.
1151 */
1152 @HotSpotIntrinsicCandidate
1153 public int intValue() {
1154 return value;
1155 }
1156
1157 /**
1158 * Returns the value of this {@code Integer} as a {@code long}
1159 * after a widening primitive conversion.
1160 * @jls 5.1.2 Widening Primitive Conversions
1161 * @see Integer#toUnsignedLong(int)
1162 */
1163 public long longValue() {
1164 return (long)value;
1165 }
1166
1167 /**
1168 * Returns the value of this {@code Integer} as a {@code float}
1169 * after a widening primitive conversion.
1170 * @jls 5.1.2 Widening Primitive Conversions
1171 */
1172 public float floatValue() {
1173 return (float)value;
1174 }
1175
1176 /**
1177 * Returns the value of this {@code Integer} as a {@code double}
1178 * after a widening primitive conversion.
1179 * @jls 5.1.2 Widening Primitive Conversions
1180 */
1181 public double doubleValue() {
1182 return (double)value;
1183 }
1184
1185 /**
1186 * Returns a {@code String} object representing this
1187 * {@code Integer}'s value. The value is converted to signed
1188 * decimal representation and returned as a string, exactly as if
1189 * the integer value were given as an argument to the {@link
1190 * java.lang.Integer#toString(int)} method.
1191 *
1192 * @return a string representation of the value of this object in
1193 * base 10.
1194 */
1195 public String toString() {
1196 return toString(value);
1197 }
1198
1199 /**
1200 * Returns a hash code for this {@code Integer}.
1201 *
1202 * @return a hash code value for this object, equal to the
1203 * primitive {@code int} value represented by this
1204 * {@code Integer} object.
1205 */
1206 @Override
1207 public int hashCode() {
1208 return Integer.hashCode(value);
1209 }
1210
1211 /**
1212 * Returns a hash code for a {@code int} value; compatible with
1213 * {@code Integer.hashCode()}.
1214 *
1215 * @param value the value to hash
1216 * @since 1.8
1217 *
1218 * @return a hash code value for a {@code int} value.
1219 */
1220 public static int hashCode(int value) {
1221 return value;
1222 }
1223
1224 /**
1225 * Compares this object to the specified object. The result is
1226 * {@code true} if and only if the argument is not
1227 * {@code null} and is an {@code Integer} object that
1228 * contains the same {@code int} value as this object.
1229 *
1230 * @param obj the object to compare with.
1231 * @return {@code true} if the objects are the same;
1232 * {@code false} otherwise.
1233 */
1234 public boolean equals(Object obj) {
1235 if (obj instanceof Integer) {
1236 return value == ((Integer)obj).intValue();
1237 }
1238 return false;
1239 }
1240
1241 /**
1242 * Determines the integer value of the system property with the
1243 * specified name.
1244 *
1245 * <p>The first argument is treated as the name of a system
1246 * property. System properties are accessible through the {@link
1247 * java.lang.System#getProperty(java.lang.String)} method. The
1248 * string value of this property is then interpreted as an integer
1249 * value using the grammar supported by {@link Integer#decode decode} and
1250 * an {@code Integer} object representing this value is returned.
1251 *
1252 * <p>If there is no property with the specified name, if the
1253 * specified name is empty or {@code null}, or if the property
1254 * does not have the correct numeric format, then {@code null} is
1255 * returned.
1256 *
1257 * <p>In other words, this method returns an {@code Integer}
1258 * object equal to the value of:
1259 *
1260 * <blockquote>
1261 * {@code getInteger(nm, null)}
1262 * </blockquote>
1263 *
1264 * @param nm property name.
1265 * @return the {@code Integer} value of the property.
1266 * @throws SecurityException for the same reasons as
1267 * {@link System#getProperty(String) System.getProperty}
1268 * @see java.lang.System#getProperty(java.lang.String)
1269 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1270 */
1271 public static Integer getInteger(String nm) {
1272 return getInteger(nm, null);
1273 }
1274
1275 /**
1276 * Determines the integer value of the system property with the
1277 * specified name.
1278 *
1279 * <p>The first argument is treated as the name of a system
1280 * property. System properties are accessible through the {@link
1281 * java.lang.System#getProperty(java.lang.String)} method. The
1282 * string value of this property is then interpreted as an integer
1283 * value using the grammar supported by {@link Integer#decode decode} and
1284 * an {@code Integer} object representing this value is returned.
1285 *
1286 * <p>The second argument is the default value. An {@code Integer} object
1287 * that represents the value of the second argument is returned if there
1288 * is no property of the specified name, if the property does not have
1289 * the correct numeric format, or if the specified name is empty or
1290 * {@code null}.
1291 *
1292 * <p>In other words, this method returns an {@code Integer} object
1293 * equal to the value of:
1294 *
1295 * <blockquote>
1296 * {@code getInteger(nm, new Integer(val))}
1297 * </blockquote>
1298 *
1299 * but in practice it may be implemented in a manner such as:
1300 *
1301 * <blockquote><pre>
1302 * Integer result = getInteger(nm, null);
1303 * return (result == null) ? new Integer(val) : result;
1304 * </pre></blockquote>
1305 *
1306 * to avoid the unnecessary allocation of an {@code Integer}
1307 * object when the default value is not needed.
1308 *
1309 * @param nm property name.
1310 * @param val default value.
1311 * @return the {@code Integer} value of the property.
1312 * @throws SecurityException for the same reasons as
1313 * {@link System#getProperty(String) System.getProperty}
1314 * @see java.lang.System#getProperty(java.lang.String)
1315 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1316 */
1317 public static Integer getInteger(String nm, int val) {
1318 Integer result = getInteger(nm, null);
1319 return (result == null) ? Integer.valueOf(val) : result;
1320 }
1321
1322 /**
1323 * Returns the integer value of the system property with the
1324 * specified name. The first argument is treated as the name of a
1325 * system property. System properties are accessible through the
1326 * {@link java.lang.System#getProperty(java.lang.String)} method.
1327 * The string value of this property is then interpreted as an
1328 * integer value, as per the {@link Integer#decode decode} method,
1329 * and an {@code Integer} object representing this value is
1330 * returned; in summary:
1331 *
1332 * <ul><li>If the property value begins with the two ASCII characters
1333 * {@code 0x} or the ASCII character {@code #}, not
1334 * followed by a minus sign, then the rest of it is parsed as a
1335 * hexadecimal integer exactly as by the method
1336 * {@link #valueOf(java.lang.String, int)} with radix 16.
1337 * <li>If the property value begins with the ASCII character
1338 * {@code 0} followed by another character, it is parsed as an
1339 * octal integer exactly as by the method
1340 * {@link #valueOf(java.lang.String, int)} with radix 8.
1341 * <li>Otherwise, the property value is parsed as a decimal integer
1342 * exactly as by the method {@link #valueOf(java.lang.String, int)}
1343 * with radix 10.
1344 * </ul>
1345 *
1346 * <p>The second argument is the default value. The default value is
1347 * returned if there is no property of the specified name, if the
1348 * property does not have the correct numeric format, or if the
1349 * specified name is empty or {@code null}.
1350 *
1351 * @param nm property name.
1352 * @param val default value.
1353 * @return the {@code Integer} value of the property.
1354 * @throws SecurityException for the same reasons as
1355 * {@link System#getProperty(String) System.getProperty}
1356 * @see System#getProperty(java.lang.String)
1357 * @see System#getProperty(java.lang.String, java.lang.String)
1358 */
1359 public static Integer getInteger(String nm, Integer val) {
1360 String v = null;
1361 try {
1362 v = System.getProperty(nm);
1363 } catch (IllegalArgumentException | NullPointerException e) {
1364 }
1365 if (v != null) {
1366 try {
1367 return Integer.decode(v);
1368 } catch (NumberFormatException e) {
1369 }
1370 }
1371 return val;
1372 }
1373
1374 /**
1375 * Decodes a {@code String} into an {@code Integer}.
1376 * Accepts decimal, hexadecimal, and octal numbers given
1377 * by the following grammar:
1378 *
1379 * <blockquote>
1380 * <dl>
1381 * <dt><i>DecodableString:</i>
1382 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1383 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1384 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1385 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1386 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1387 *
1388 * <dt><i>Sign:</i>
1389 * <dd>{@code -}
1390 * <dd>{@code +}
1391 * </dl>
1392 * </blockquote>
1393 *
1394 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1395 * are as defined in section 3.10.1 of
1396 * <cite>The Java™ Language Specification</cite>,
1397 * except that underscores are not accepted between digits.
1398 *
1399 * <p>The sequence of characters following an optional
1400 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1401 * "{@code #}", or leading zero) is parsed as by the {@code
1402 * Integer.parseInt} method with the indicated radix (10, 16, or
1403 * 8). This sequence of characters must represent a positive
1404 * value or a {@link NumberFormatException} will be thrown. The
1405 * result is negated if first character of the specified {@code
1406 * String} is the minus sign. No whitespace characters are
1407 * permitted in the {@code String}.
1408 *
1409 * @param nm the {@code String} to decode.
1410 * @return an {@code Integer} object holding the {@code int}
1411 * value represented by {@code nm}
1412 * @exception NumberFormatException if the {@code String} does not
1413 * contain a parsable integer.
1414 * @see java.lang.Integer#parseInt(java.lang.String, int)
1415 */
1416 public static Integer decode(String nm) throws NumberFormatException {
1417 int radix = 10;
1418 int index = 0;
1419 boolean negative = false;
1420 Integer result;
1421
1422 if (nm.length() == 0)
1423 throw new NumberFormatException("Zero length string");
1424 char firstChar = nm.charAt(0);
1425 // Handle sign, if present
1426 if (firstChar == '-') {
1427 negative = true;
1428 index++;
1429 } else if (firstChar == '+')
1430 index++;
1431
1432 // Handle radix specifier, if present
1433 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1434 index += 2;
1435 radix = 16;
1436 }
1437 else if (nm.startsWith("#", index)) {
1438 index ++;
1439 radix = 16;
1440 }
1441 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1442 index ++;
1443 radix = 8;
1444 }
1445
1446 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1447 throw new NumberFormatException("Sign character in wrong position");
1448
1449 try {
1450 result = Integer.valueOf(nm.substring(index), radix);
1451 result = negative ? Integer.valueOf(-result.intValue()) : result;
1452 } catch (NumberFormatException e) {
1453 // If number is Integer.MIN_VALUE, we'll end up here. The next line
1454 // handles this case, and causes any genuine format error to be
1455 // rethrown.
1456 String constant = negative ? ("-" + nm.substring(index))
1457 : nm.substring(index);
1458 result = Integer.valueOf(constant, radix);
1459 }
1460 return result;
1461 }
1462
1463 /**
1464 * Compares two {@code Integer} objects numerically.
1465 *
1466 * @param anotherInteger the {@code Integer} to be compared.
1467 * @return the value {@code 0} if this {@code Integer} is
1468 * equal to the argument {@code Integer}; a value less than
1469 * {@code 0} if this {@code Integer} is numerically less
1470 * than the argument {@code Integer}; and a value greater
1471 * than {@code 0} if this {@code Integer} is numerically
1472 * greater than the argument {@code Integer} (signed
1473 * comparison).
1474 * @since 1.2
1475 */
1476 public int compareTo(Integer anotherInteger) {
1477 return compare(this.value, anotherInteger.value);
1478 }
1479
1480 /**
1481 * Compares two {@code int} values numerically.
1482 * The value returned is identical to what would be returned by:
1483 * <pre>
1484 * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1485 * </pre>
1486 *
1487 * @param x the first {@code int} to compare
1488 * @param y the second {@code int} to compare
1489 * @return the value {@code 0} if {@code x == y};
1490 * a value less than {@code 0} if {@code x < y}; and
1491 * a value greater than {@code 0} if {@code x > y}
1492 * @since 1.7
1493 */
1494 public static int compare(int x, int y) {
1495 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1496 }
1497
1498 /**
1499 * Compares two {@code int} values numerically treating the values
1500 * as unsigned.
1501 *
1502 * @param x the first {@code int} to compare
1503 * @param y the second {@code int} to compare
1504 * @return the value {@code 0} if {@code x == y}; a value less
1505 * than {@code 0} if {@code x < y} as unsigned values; and
1506 * a value greater than {@code 0} if {@code x > y} as
1507 * unsigned values
1508 * @since 1.8
1509 */
1510 public static int compareUnsigned(int x, int y) {
1511 return compare(x + MIN_VALUE, y + MIN_VALUE);
1512 }
1513
1514 /**
1515 * Converts the argument to a {@code long} by an unsigned
1516 * conversion. In an unsigned conversion to a {@code long}, the
1517 * high-order 32 bits of the {@code long} are zero and the
1518 * low-order 32 bits are equal to the bits of the integer
1519 * argument.
1520 *
1521 * Consequently, zero and positive {@code int} values are mapped
1522 * to a numerically equal {@code long} value and negative {@code
1523 * int} values are mapped to a {@code long} value equal to the
1524 * input plus 2<sup>32</sup>.
1525 *
1526 * @param x the value to convert to an unsigned {@code long}
1527 * @return the argument converted to {@code long} by an unsigned
1528 * conversion
1529 * @since 1.8
1530 */
1531 public static long toUnsignedLong(int x) {
1532 return ((long) x) & 0xffffffffL;
1533 }
1534
1535 /**
1536 * Returns the unsigned quotient of dividing the first argument by
1537 * the second where each argument and the result is interpreted as
1538 * an unsigned value.
1539 *
1540 * <p>Note that in two's complement arithmetic, the three other
1541 * basic arithmetic operations of add, subtract, and multiply are
1542 * bit-wise identical if the two operands are regarded as both
1543 * being signed or both being unsigned. Therefore separate {@code
1544 * addUnsigned}, etc. methods are not provided.
1545 *
1546 * @param dividend the value to be divided
1547 * @param divisor the value doing the dividing
1548 * @return the unsigned quotient of the first argument divided by
1549 * the second argument
1550 * @see #remainderUnsigned
1551 * @since 1.8
1552 */
1553 public static int divideUnsigned(int dividend, int divisor) {
1554 // In lieu of tricky code, for now just use long arithmetic.
1555 return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor));
1556 }
1557
1558 /**
1559 * Returns the unsigned remainder from dividing the first argument
1560 * by the second where each argument and the result is interpreted
1561 * as an unsigned value.
1562 *
1563 * @param dividend the value to be divided
1564 * @param divisor the value doing the dividing
1565 * @return the unsigned remainder of the first argument divided by
1566 * the second argument
1567 * @see #divideUnsigned
1568 * @since 1.8
1569 */
1570 public static int remainderUnsigned(int dividend, int divisor) {
1571 // In lieu of tricky code, for now just use long arithmetic.
1572 return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor));
1573 }
1574
1575
1576 // Bit twiddling
1577
1578 /**
1579 * The number of bits used to represent an {@code int} value in two's
1580 * complement binary form.
1581 *
1582 * @since 1.5
1583 */
1584 @Native public static final int SIZE = 32;
1585
1586 /**
1587 * The number of bytes used to represent a {@code int} value in two's
1588 * complement binary form.
1589 *
1590 * @since 1.8
1591 */
1592 public static final int BYTES = SIZE / Byte.SIZE;
1593
1594 /**
1595 * Returns an {@code int} value with at most a single one-bit, in the
1596 * position of the highest-order ("leftmost") one-bit in the specified
1597 * {@code int} value. Returns zero if the specified value has no
1598 * one-bits in its two's complement binary representation, that is, if it
1599 * is equal to zero.
1600 *
1601 * @param i the value whose highest one bit is to be computed
1602 * @return an {@code int} value with a single one-bit, in the position
1603 * of the highest-order one-bit in the specified value, or zero if
1604 * the specified value is itself equal to zero.
1605 * @since 1.5
1606 */
1607 public static int highestOneBit(int i) {
1608 // HD, Figure 3-1
1609 i |= (i >> 1);
1610 i |= (i >> 2);
1611 i |= (i >> 4);
1612 i |= (i >> 8);
1613 i |= (i >> 16);
1614 return i - (i >>> 1);
1615 }
1616
1617 /**
1618 * Returns an {@code int} value with at most a single one-bit, in the
1619 * position of the lowest-order ("rightmost") one-bit in the specified
1620 * {@code int} value. Returns zero if the specified value has no
1621 * one-bits in its two's complement binary representation, that is, if it
1622 * is equal to zero.
1623 *
1624 * @param i the value whose lowest one bit is to be computed
1625 * @return an {@code int} value with a single one-bit, in the position
1626 * of the lowest-order one-bit in the specified value, or zero if
1627 * the specified value is itself equal to zero.
1628 * @since 1.5
1629 */
1630 public static int lowestOneBit(int i) {
1631 // HD, Section 2-1
1632 return i & -i;
1633 }
1634
1635 /**
1636 * Returns the number of zero bits preceding the highest-order
1637 * ("leftmost") one-bit in the two's complement binary representation
1638 * of the specified {@code int} value. Returns 32 if the
1639 * specified value has no one-bits in its two's complement representation,
1640 * in other words if it is equal to zero.
1641 *
1642 * <p>Note that this method is closely related to the logarithm base 2.
1643 * For all positive {@code int} values x:
1644 * <ul>
1645 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1646 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1647 * </ul>
1648 *
1649 * @param i the value whose number of leading zeros is to be computed
1650 * @return the number of zero bits preceding the highest-order
1651 * ("leftmost") one-bit in the two's complement binary representation
1652 * of the specified {@code int} value, or 32 if the value
1653 * is equal to zero.
1654 * @since 1.5
1655 */
1656 @HotSpotIntrinsicCandidate
1657 public static int numberOfLeadingZeros(int i) {
1658 // HD, Figure 5-6
1659 if (i == 0)
1660 return 32;
1661 int n = 1;
1662 if (i >>> 16 == 0) { n += 16; i <<= 16; }
1663 if (i >>> 24 == 0) { n += 8; i <<= 8; }
1664 if (i >>> 28 == 0) { n += 4; i <<= 4; }
1665 if (i >>> 30 == 0) { n += 2; i <<= 2; }
1666 n -= i >>> 31;
1667 return n;
1668 }
1669
1670 /**
1671 * Returns the number of zero bits following the lowest-order ("rightmost")
1672 * one-bit in the two's complement binary representation of the specified
1673 * {@code int} value. Returns 32 if the specified value has no
1674 * one-bits in its two's complement representation, in other words if it is
1675 * equal to zero.
1676 *
1677 * @param i the value whose number of trailing zeros is to be computed
1678 * @return the number of zero bits following the lowest-order ("rightmost")
1679 * one-bit in the two's complement binary representation of the
1680 * specified {@code int} value, or 32 if the value is equal
1681 * to zero.
1682 * @since 1.5
1683 */
1684 @HotSpotIntrinsicCandidate
1685 public static int numberOfTrailingZeros(int i) {
1686 // HD, Figure 5-14
1687 int y;
1688 if (i == 0) return 32;
1689 int n = 31;
1690 y = i <<16; if (y != 0) { n = n -16; i = y; }
1691 y = i << 8; if (y != 0) { n = n - 8; i = y; }
1692 y = i << 4; if (y != 0) { n = n - 4; i = y; }
1693 y = i << 2; if (y != 0) { n = n - 2; i = y; }
1694 return n - ((i << 1) >>> 31);
1695 }
1696
1697 /**
1698 * Returns the number of one-bits in the two's complement binary
1699 * representation of the specified {@code int} value. This function is
1700 * sometimes referred to as the <i>population count</i>.
1701 *
1702 * @param i the value whose bits are to be counted
1703 * @return the number of one-bits in the two's complement binary
1704 * representation of the specified {@code int} value.
1705 * @since 1.5
1706 */
1707 @HotSpotIntrinsicCandidate
1708 public static int bitCount(int i) {
1709 // HD, Figure 5-2
1710 i = i - ((i >>> 1) & 0x55555555);
1711 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1712 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1713 i = i + (i >>> 8);
1714 i = i + (i >>> 16);
1715 return i & 0x3f;
1716 }
1717
1718 /**
1719 * Returns the value obtained by rotating the two's complement binary
1720 * representation of the specified {@code int} value left by the
1721 * specified number of bits. (Bits shifted out of the left hand, or
1722 * high-order, side reenter on the right, or low-order.)
1723 *
1724 * <p>Note that left rotation with a negative distance is equivalent to
1725 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1726 * distance)}. Note also that rotation by any multiple of 32 is a
1727 * no-op, so all but the last five bits of the rotation distance can be
1728 * ignored, even if the distance is negative: {@code rotateLeft(val,
1729 * distance) == rotateLeft(val, distance & 0x1F)}.
1730 *
1731 * @param i the value whose bits are to be rotated left
1732 * @param distance the number of bit positions to rotate left
1733 * @return the value obtained by rotating the two's complement binary
1734 * representation of the specified {@code int} value left by the
1735 * specified number of bits.
1736 * @since 1.5
1737 */
1738 public static int rotateLeft(int i, int distance) {
1739 return (i << distance) | (i >>> -distance);
1740 }
1741
1742 /**
1743 * Returns the value obtained by rotating the two's complement binary
1744 * representation of the specified {@code int} value right by the
1745 * specified number of bits. (Bits shifted out of the right hand, or
1746 * low-order, side reenter on the left, or high-order.)
1747 *
1748 * <p>Note that right rotation with a negative distance is equivalent to
1749 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1750 * distance)}. Note also that rotation by any multiple of 32 is a
1751 * no-op, so all but the last five bits of the rotation distance can be
1752 * ignored, even if the distance is negative: {@code rotateRight(val,
1753 * distance) == rotateRight(val, distance & 0x1F)}.
1754 *
1755 * @param i the value whose bits are to be rotated right
1756 * @param distance the number of bit positions to rotate right
1757 * @return the value obtained by rotating the two's complement binary
1758 * representation of the specified {@code int} value right by the
1759 * specified number of bits.
1760 * @since 1.5
1761 */
1762 public static int rotateRight(int i, int distance) {
1763 return (i >>> distance) | (i << -distance);
1764 }
1765
1766 /**
1767 * Returns the value obtained by reversing the order of the bits in the
1768 * two's complement binary representation of the specified {@code int}
1769 * value.
1770 *
1771 * @param i the value to be reversed
1772 * @return the value obtained by reversing order of the bits in the
1773 * specified {@code int} value.
1774 * @since 1.5
1775 */
1776 public static int reverse(int i) {
1777 // HD, Figure 7-1
1778 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1779 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1780 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1781 i = (i << 24) | ((i & 0xff00) << 8) |
1782 ((i >>> 8) & 0xff00) | (i >>> 24);
1783 return i;
1784 }
1785
1786 /**
1787 * Returns the signum function of the specified {@code int} value. (The
1788 * return value is -1 if the specified value is negative; 0 if the
1789 * specified value is zero; and 1 if the specified value is positive.)
1790 *
1791 * @param i the value whose signum is to be computed
1792 * @return the signum function of the specified {@code int} value.
1793 * @since 1.5
1794 */
1795 public static int signum(int i) {
1796 // HD, Section 2-7
1797 return (i >> 31) | (-i >>> 31);
1798 }
1799
1800 /**
1801 * Returns the value obtained by reversing the order of the bytes in the
1802 * two's complement representation of the specified {@code int} value.
1803 *
1804 * @param i the value whose bytes are to be reversed
1805 * @return the value obtained by reversing the bytes in the specified
1806 * {@code int} value.
1807 * @since 1.5
1808 */
1809 @HotSpotIntrinsicCandidate
1810 public static int reverseBytes(int i) {
1811 return ((i >>> 24) ) |
1812 ((i >> 8) & 0xFF00) |
1813 ((i << 8) & 0xFF0000) |
1814 ((i << 24));
1815 }
1816
1817 /**
1818 * Adds two integers together as per the + operator.
1819 *
1820 * @param a the first operand
1821 * @param b the second operand
1822 * @return the sum of {@code a} and {@code b}
1823 * @see java.util.function.BinaryOperator
1824 * @since 1.8
1825 */
1826 public static int sum(int a, int b) {
1827 return a + b;
1828 }
1829
1830 /**
1831 * Returns the greater of two {@code int} values
1832 * as if by calling {@link Math#max(int, int) Math.max}.
1833 *
1834 * @param a the first operand
1835 * @param b the second operand
1836 * @return the greater of {@code a} and {@code b}
1837 * @see java.util.function.BinaryOperator
1838 * @since 1.8
1839 */
1840 public static int max(int a, int b) {
1841 return Math.max(a, b);
1842 }
1843
1844 /**
1845 * Returns the smaller of two {@code int} values
1846 * as if by calling {@link Math#min(int, int) Math.min}.
1847 *
1848 * @param a the first operand
1849 * @param b the second operand
1850 * @return the smaller of {@code a} and {@code b}
1851 * @see java.util.function.BinaryOperator
1852 * @since 1.8
1853 */
1854 public static int min(int a, int b) {
1855 return Math.min(a, b);
1856 }
1857
1858 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1859 @Native private static final long serialVersionUID = 1360826667806852920L;
1860 }