This repository has been archived by the owner on Sep 2, 2022. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 78
/
Integer.java
1870 lines (1758 loc) · 71.6 KB
/
Integer.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Copyright (c) 1994, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang;
import java.lang.annotation.Native;
import java.lang.invoke.MethodHandles;
import java.lang.constant.Constable;
import java.lang.constant.ConstantDesc;
import java.util.Objects;
import java.util.Optional;
import jdk.internal.misc.CDS;
import jdk.internal.misc.VM;
import jdk.internal.vm.annotation.IntrinsicCandidate;
import static java.lang.String.COMPACT_STRINGS;
import static java.lang.String.LATIN1;
import static java.lang.String.UTF16;
/**
* The {@code Integer} class wraps a value of the primitive type
* {@code int} in an object. An object of type {@code Integer}
* contains a single field whose type is {@code int}.
*
* <p>In addition, this class provides several methods for converting
* an {@code int} to a {@code String} and a {@code String} to an
* {@code int}, as well as other constants and methods useful when
* dealing with an {@code int}.
*
* <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
* class; programmers should treat instances that are
* {@linkplain #equals(Object) equal} as interchangeable and should not
* use instances for synchronization, or unpredictable behavior may
* occur. For example, in a future release, synchronization may fail.
*
* <p>Implementation note: The implementations of the "bit twiddling"
* methods (such as {@link #highestOneBit(int) highestOneBit} and
* {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
* based on material from Henry S. Warren, Jr.'s <i>Hacker's
* Delight</i>, (Addison Wesley, 2002).
*
* @author Lee Boynton
* @author Arthur van Hoff
* @author Josh Bloch
* @author Joseph D. Darcy
* @since 1.0
*/
@jdk.internal.ValueBased
public final class Integer extends Number
implements Comparable<Integer>, Constable, ConstantDesc {
/**
* A constant holding the minimum value an {@code int} can
* have, -2<sup>31</sup>.
*/
@Native public static final int MIN_VALUE = 0x80000000;
/**
* A constant holding the maximum value an {@code int} can
* have, 2<sup>31</sup>-1.
*/
@Native public static final int MAX_VALUE = 0x7fffffff;
/**
* The {@code Class} instance representing the primitive type
* {@code int}.
*
* @since 1.1
*/
@SuppressWarnings("unchecked")
public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
/**
* All possible chars for representing a number as a String
*/
static final char[] digits = {
'0' , '1' , '2' , '3' , '4' , '5' ,
'6' , '7' , '8' , '9' , 'a' , 'b' ,
'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
'o' , 'p' , 'q' , 'r' , 's' , 't' ,
'u' , 'v' , 'w' , 'x' , 'y' , 'z'
};
/**
* Returns a string representation of the first argument in the
* radix specified by the second argument.
*
* <p>If the radix is smaller than {@code Character.MIN_RADIX}
* or larger than {@code Character.MAX_RADIX}, then the radix
* {@code 10} is used instead.
*
* <p>If the first argument is negative, the first element of the
* result is the ASCII minus character {@code '-'}
* ({@code '\u005Cu002D'}). If the first argument is not
* negative, no sign character appears in the result.
*
* <p>The remaining characters of the result represent the magnitude
* of the first argument. If the magnitude is zero, it is
* represented by a single zero character {@code '0'}
* ({@code '\u005Cu0030'}); otherwise, the first character of
* the representation of the magnitude will not be the zero
* character. The following ASCII characters are used as digits:
*
* <blockquote>
* {@code 0123456789abcdefghijklmnopqrstuvwxyz}
* </blockquote>
*
* These are {@code '\u005Cu0030'} through
* {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
* {@code '\u005Cu007A'}. If {@code radix} is
* <var>N</var>, then the first <var>N</var> of these characters
* are used as radix-<var>N</var> digits in the order shown. Thus,
* the digits for hexadecimal (radix 16) are
* {@code 0123456789abcdef}. If uppercase letters are
* desired, the {@link java.lang.String#toUpperCase()} method may
* be called on the result:
*
* <blockquote>
* {@code Integer.toString(n, 16).toUpperCase()}
* </blockquote>
*
* @param i an integer to be converted to a string.
* @param radix the radix to use in the string representation.
* @return a string representation of the argument in the specified radix.
* @see java.lang.Character#MAX_RADIX
* @see java.lang.Character#MIN_RADIX
*/
public static String toString(int i, int radix) {
if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
radix = 10;
/* Use the faster version */
if (radix == 10) {
return toString(i);
}
if (COMPACT_STRINGS) {
byte[] buf = new byte[33];
boolean negative = (i < 0);
int charPos = 32;
if (!negative) {
i = -i;
}
while (i <= -radix) {
buf[charPos--] = (byte)digits[-(i % radix)];
i = i / radix;
}
buf[charPos] = (byte)digits[-i];
if (negative) {
buf[--charPos] = '-';
}
return StringLatin1.newString(buf, charPos, (33 - charPos));
}
return toStringUTF16(i, radix);
}
private static String toStringUTF16(int i, int radix) {
byte[] buf = new byte[33 * 2];
boolean negative = (i < 0);
int charPos = 32;
if (!negative) {
i = -i;
}
while (i <= -radix) {
StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
i = i / radix;
}
StringUTF16.putChar(buf, charPos, digits[-i]);
if (negative) {
StringUTF16.putChar(buf, --charPos, '-');
}
return StringUTF16.newString(buf, charPos, (33 - charPos));
}
/**
* Returns a string representation of the first argument as an
* unsigned integer value in the radix specified by the second
* argument.
*
* <p>If the radix is smaller than {@code Character.MIN_RADIX}
* or larger than {@code Character.MAX_RADIX}, then the radix
* {@code 10} is used instead.
*
* <p>Note that since the first argument is treated as an unsigned
* value, no leading sign character is printed.
*
* <p>If the magnitude is zero, it is represented by a single zero
* character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
* the first character of the representation of the magnitude will
* not be the zero character.
*
* <p>The behavior of radixes and the characters used as digits
* are the same as {@link #toString(int, int) toString}.
*
* @param i an integer to be converted to an unsigned string.
* @param radix the radix to use in the string representation.
* @return an unsigned string representation of the argument in the specified radix.
* @see #toString(int, int)
* @since 1.8
*/
public static String toUnsignedString(int i, int radix) {
return Long.toUnsignedString(toUnsignedLong(i), radix);
}
/**
* Returns a string representation of the integer argument as an
* unsigned integer in base 16.
*
* <p>The unsigned integer value is the argument plus 2<sup>32</sup>
* if the argument is negative; otherwise, it is equal to the
* argument. This value is converted to a string of ASCII digits
* in hexadecimal (base 16) with no extra leading
* {@code 0}s.
*
* <p>The value of the argument can be recovered from the returned
* string {@code s} by calling {@link
* Integer#parseUnsignedInt(String, int)
* Integer.parseUnsignedInt(s, 16)}.
*
* <p>If the unsigned magnitude is zero, it is represented by a
* single zero character {@code '0'} ({@code '\u005Cu0030'});
* otherwise, the first character of the representation of the
* unsigned magnitude will not be the zero character. The
* following characters are used as hexadecimal digits:
*
* <blockquote>
* {@code 0123456789abcdef}
* </blockquote>
*
* These are the characters {@code '\u005Cu0030'} through
* {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
* {@code '\u005Cu0066'}. If uppercase letters are
* desired, the {@link java.lang.String#toUpperCase()} method may
* be called on the result:
*
* <blockquote>
* {@code Integer.toHexString(n).toUpperCase()}
* </blockquote>
*
* @param i an integer to be converted to a string.
* @return the string representation of the unsigned integer value
* represented by the argument in hexadecimal (base 16).
* @see #parseUnsignedInt(String, int)
* @see #toUnsignedString(int, int)
* @since 1.0.2
*/
public static String toHexString(int i) {
return toUnsignedString0(i, 4);
}
/**
* Returns a string representation of the integer argument as an
* unsigned integer in base 8.
*
* <p>The unsigned integer value is the argument plus 2<sup>32</sup>
* if the argument is negative; otherwise, it is equal to the
* argument. This value is converted to a string of ASCII digits
* in octal (base 8) with no extra leading {@code 0}s.
*
* <p>The value of the argument can be recovered from the returned
* string {@code s} by calling {@link
* Integer#parseUnsignedInt(String, int)
* Integer.parseUnsignedInt(s, 8)}.
*
* <p>If the unsigned magnitude is zero, it is represented by a
* single zero character {@code '0'} ({@code '\u005Cu0030'});
* otherwise, the first character of the representation of the
* unsigned magnitude will not be the zero character. The
* following characters are used as octal digits:
*
* <blockquote>
* {@code 01234567}
* </blockquote>
*
* These are the characters {@code '\u005Cu0030'} through
* {@code '\u005Cu0037'}.
*
* @param i an integer to be converted to a string.
* @return the string representation of the unsigned integer value
* represented by the argument in octal (base 8).
* @see #parseUnsignedInt(String, int)
* @see #toUnsignedString(int, int)
* @since 1.0.2
*/
public static String toOctalString(int i) {
return toUnsignedString0(i, 3);
}
/**
* Returns a string representation of the integer argument as an
* unsigned integer in base 2.
*
* <p>The unsigned integer value is the argument plus 2<sup>32</sup>
* if the argument is negative; otherwise it is equal to the
* argument. This value is converted to a string of ASCII digits
* in binary (base 2) with no extra leading {@code 0}s.
*
* <p>The value of the argument can be recovered from the returned
* string {@code s} by calling {@link
* Integer#parseUnsignedInt(String, int)
* Integer.parseUnsignedInt(s, 2)}.
*
* <p>If the unsigned magnitude is zero, it is represented by a
* single zero character {@code '0'} ({@code '\u005Cu0030'});
* otherwise, the first character of the representation of the
* unsigned magnitude will not be the zero character. The
* characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
* '1'} ({@code '\u005Cu0031'}) are used as binary digits.
*
* @param i an integer to be converted to a string.
* @return the string representation of the unsigned integer value
* represented by the argument in binary (base 2).
* @see #parseUnsignedInt(String, int)
* @see #toUnsignedString(int, int)
* @since 1.0.2
*/
public static String toBinaryString(int i) {
return toUnsignedString0(i, 1);
}
/**
* Convert the integer to an unsigned number.
*/
private static String toUnsignedString0(int val, int shift) {
// assert shift > 0 && shift <=5 : "Illegal shift value";
int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
int chars = Math.max(((mag + (shift - 1)) / shift), 1);
if (COMPACT_STRINGS) {
byte[] buf = new byte[chars];
formatUnsignedInt(val, shift, buf, chars);
return new String(buf, LATIN1);
} else {
byte[] buf = new byte[chars * 2];
formatUnsignedIntUTF16(val, shift, buf, chars);
return new String(buf, UTF16);
}
}
/**
* Format an {@code int} (treated as unsigned) into a byte buffer (LATIN1 version). If
* {@code len} exceeds the formatted ASCII representation of {@code val},
* {@code buf} will be padded with leading zeroes.
*
* @param val the unsigned int to format
* @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
* @param buf the byte buffer to write to
* @param len the number of characters to write
*/
private static void formatUnsignedInt(int val, int shift, byte[] buf, int len) {
int charPos = len;
int radix = 1 << shift;
int mask = radix - 1;
do {
buf[--charPos] = (byte)Integer.digits[val & mask];
val >>>= shift;
} while (charPos > 0);
}
/**
* Format an {@code int} (treated as unsigned) into a byte buffer (UTF16 version). If
* {@code len} exceeds the formatted ASCII representation of {@code val},
* {@code buf} will be padded with leading zeroes.
*
* @param val the unsigned int to format
* @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
* @param buf the byte buffer to write to
* @param len the number of characters to write
*/
private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int len) {
int charPos = len;
int radix = 1 << shift;
int mask = radix - 1;
do {
StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
val >>>= shift;
} while (charPos > 0);
}
static final byte[] DigitTens = {
'0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
'1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
'2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
'3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
'4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
'5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
'6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
'7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
'8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
'9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
} ;
static final byte[] DigitOnes = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
} ;
/**
* Returns a {@code String} object representing the
* specified integer. The argument is converted to signed decimal
* representation and returned as a string, exactly as if the
* argument and radix 10 were given as arguments to the {@link
* #toString(int, int)} method.
*
* @param i an integer to be converted.
* @return a string representation of the argument in base 10.
*/
@IntrinsicCandidate
public static String toString(int i) {
int size = stringSize(i);
if (COMPACT_STRINGS) {
byte[] buf = new byte[size];
getChars(i, size, buf);
return new String(buf, LATIN1);
} else {
byte[] buf = new byte[size * 2];
StringUTF16.getChars(i, size, buf);
return new String(buf, UTF16);
}
}
/**
* Returns a string representation of the argument as an unsigned
* decimal value.
*
* The argument is converted to unsigned decimal representation
* and returned as a string exactly as if the argument and radix
* 10 were given as arguments to the {@link #toUnsignedString(int,
* int)} method.
*
* @param i an integer to be converted to an unsigned string.
* @return an unsigned string representation of the argument.
* @see #toUnsignedString(int, int)
* @since 1.8
*/
public static String toUnsignedString(int i) {
return Long.toString(toUnsignedLong(i));
}
/**
* Places characters representing the integer i into the
* character array buf. The characters are placed into
* the buffer backwards starting with the least significant
* digit at the specified index (exclusive), and working
* backwards from there.
*
* @implNote This method converts positive inputs into negative
* values, to cover the Integer.MIN_VALUE case. Converting otherwise
* (negative to positive) will expose -Integer.MIN_VALUE that overflows
* integer.
*
* @param i value to convert
* @param index next index, after the least significant digit
* @param buf target buffer, Latin1-encoded
* @return index of the most significant digit or minus sign, if present
*/
static int getChars(int i, int index, byte[] buf) {
int q, r;
int charPos = index;
boolean negative = i < 0;
if (!negative) {
i = -i;
}
// Generate two digits per iteration
while (i <= -100) {
q = i / 100;
r = (q * 100) - i;
i = q;
buf[--charPos] = DigitOnes[r];
buf[--charPos] = DigitTens[r];
}
// We know there are at most two digits left at this point.
q = i / 10;
r = (q * 10) - i;
buf[--charPos] = (byte)('0' + r);
// Whatever left is the remaining digit.
if (q < 0) {
buf[--charPos] = (byte)('0' - q);
}
if (negative) {
buf[--charPos] = (byte)'-';
}
return charPos;
}
// Left here for compatibility reasons, see JDK-8143900.
static final int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
99999999, 999999999, Integer.MAX_VALUE };
/**
* Returns the string representation size for a given int value.
*
* @param x int value
* @return string size
*
* @implNote There are other ways to compute this: e.g. binary search,
* but values are biased heavily towards zero, and therefore linear search
* wins. The iteration results are also routinely inlined in the generated
* code after loop unrolling.
*/
static int stringSize(int x) {
int d = 1;
if (x >= 0) {
d = 0;
x = -x;
}
int p = -10;
for (int i = 1; i < 10; i++) {
if (x > p)
return i + d;
p = 10 * p;
}
return 10 + d;
}
/**
* Parses the string argument as a signed integer in the radix
* specified by the second argument. The characters in the string
* must all be digits of the specified radix (as determined by
* whether {@link java.lang.Character#digit(char, int)} returns a
* nonnegative value), except that the first character may be an
* ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
* indicate a negative value or an ASCII plus sign {@code '+'}
* ({@code '\u005Cu002B'}) to indicate a positive value. The
* resulting integer value is returned.
*
* <p>An exception of type {@code NumberFormatException} is
* thrown if any of the following situations occurs:
* <ul>
* <li>The first argument is {@code null} or is a string of
* length zero.
*
* <li>The radix is either smaller than
* {@link java.lang.Character#MIN_RADIX} or
* larger than {@link java.lang.Character#MAX_RADIX}.
*
* <li>Any character of the string is not a digit of the specified
* radix, except that the first character may be a minus sign
* {@code '-'} ({@code '\u005Cu002D'}) or plus sign
* {@code '+'} ({@code '\u005Cu002B'}) provided that the
* string is longer than length 1.
*
* <li>The value represented by the string is not a value of type
* {@code int}.
* </ul>
*
* <p>Examples:
* <blockquote><pre>
* parseInt("0", 10) returns 0
* parseInt("473", 10) returns 473
* parseInt("+42", 10) returns 42
* parseInt("-0", 10) returns 0
* parseInt("-FF", 16) returns -255
* parseInt("1100110", 2) returns 102
* parseInt("2147483647", 10) returns 2147483647
* parseInt("-2147483648", 10) returns -2147483648
* parseInt("2147483648", 10) throws a NumberFormatException
* parseInt("99", 8) throws a NumberFormatException
* parseInt("Kona", 10) throws a NumberFormatException
* parseInt("Kona", 27) returns 411787
* </pre></blockquote>
*
* @param s the {@code String} containing the integer
* representation to be parsed
* @param radix the radix to be used while parsing {@code s}.
* @return the integer represented by the string argument in the
* specified radix.
* @throws NumberFormatException if the {@code String}
* does not contain a parsable {@code int}.
*/
public static int parseInt(String s, int radix)
throws NumberFormatException
{
/*
* WARNING: This method may be invoked early during VM initialization
* before IntegerCache is initialized. Care must be taken to not use
* the valueOf method.
*/
if (s == null) {
throw new NumberFormatException("null");
}
if (radix < Character.MIN_RADIX) {
throw new NumberFormatException("radix " + radix +
" less than Character.MIN_RADIX");
}
if (radix > Character.MAX_RADIX) {
throw new NumberFormatException("radix " + radix +
" greater than Character.MAX_RADIX");
}
boolean negative = false;
int i = 0, len = s.length();
int limit = -Integer.MAX_VALUE;
if (len > 0) {
char firstChar = s.charAt(0);
if (firstChar < '0') { // Possible leading "+" or "-"
if (firstChar == '-') {
negative = true;
limit = Integer.MIN_VALUE;
} else if (firstChar != '+') {
throw NumberFormatException.forInputString(s, radix);
}
if (len == 1) { // Cannot have lone "+" or "-"
throw NumberFormatException.forInputString(s, radix);
}
i++;
}
int multmin = limit / radix;
int result = 0;
while (i < len) {
// Accumulating negatively avoids surprises near MAX_VALUE
int digit = Character.digit(s.charAt(i++), radix);
if (digit < 0 || result < multmin) {
throw NumberFormatException.forInputString(s, radix);
}
result *= radix;
if (result < limit + digit) {
throw NumberFormatException.forInputString(s, radix);
}
result -= digit;
}
return negative ? result : -result;
} else {
throw NumberFormatException.forInputString(s, radix);
}
}
/**
* Parses the {@link CharSequence} argument as a signed {@code int} in the
* specified {@code radix}, beginning at the specified {@code beginIndex}
* and extending to {@code endIndex - 1}.
*
* <p>The method does not take steps to guard against the
* {@code CharSequence} being mutated while parsing.
*
* @param s the {@code CharSequence} containing the {@code int}
* representation to be parsed
* @param beginIndex the beginning index, inclusive.
* @param endIndex the ending index, exclusive.
* @param radix the radix to be used while parsing {@code s}.
* @return the signed {@code int} represented by the subsequence in
* the specified radix.
* @throws NullPointerException if {@code s} is null.
* @throws IndexOutOfBoundsException if {@code beginIndex} is
* negative, or if {@code beginIndex} is greater than
* {@code endIndex} or if {@code endIndex} is greater than
* {@code s.length()}.
* @throws NumberFormatException if the {@code CharSequence} does not
* contain a parsable {@code int} in the specified
* {@code radix}, or if {@code radix} is either smaller than
* {@link java.lang.Character#MIN_RADIX} or larger than
* {@link java.lang.Character#MAX_RADIX}.
* @since 9
*/
public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
throws NumberFormatException {
Objects.requireNonNull(s);
if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
throw new IndexOutOfBoundsException();
}
if (radix < Character.MIN_RADIX) {
throw new NumberFormatException("radix " + radix +
" less than Character.MIN_RADIX");
}
if (radix > Character.MAX_RADIX) {
throw new NumberFormatException("radix " + radix +
" greater than Character.MAX_RADIX");
}
boolean negative = false;
int i = beginIndex;
int limit = -Integer.MAX_VALUE;
if (i < endIndex) {
char firstChar = s.charAt(i);
if (firstChar < '0') { // Possible leading "+" or "-"
if (firstChar == '-') {
negative = true;
limit = Integer.MIN_VALUE;
} else if (firstChar != '+') {
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
i++;
if (i == endIndex) { // Cannot have lone "+" or "-"
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
}
int multmin = limit / radix;
int result = 0;
while (i < endIndex) {
// Accumulating negatively avoids surprises near MAX_VALUE
int digit = Character.digit(s.charAt(i), radix);
if (digit < 0 || result < multmin) {
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
result *= radix;
if (result < limit + digit) {
throw NumberFormatException.forCharSequence(s, beginIndex,
endIndex, i);
}
i++;
result -= digit;
}
return negative ? result : -result;
} else {
throw NumberFormatException.forInputString("", radix);
}
}
/**
* Parses the string argument as a signed decimal integer. The
* characters in the string must all be decimal digits, except
* that the first character may be an ASCII minus sign {@code '-'}
* ({@code '\u005Cu002D'}) to indicate a negative value or an
* ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
* indicate a positive value. The resulting integer value is
* returned, exactly as if the argument and the radix 10 were
* given as arguments to the {@link #parseInt(java.lang.String,
* int)} method.
*
* @param s a {@code String} containing the {@code int}
* representation to be parsed
* @return the integer value represented by the argument in decimal.
* @throws NumberFormatException if the string does not contain a
* parsable integer.
*/
public static int parseInt(String s) throws NumberFormatException {
return parseInt(s,10);
}
/**
* Parses the string argument as an unsigned integer in the radix
* specified by the second argument. An unsigned integer maps the
* values usually associated with negative numbers to positive
* numbers larger than {@code MAX_VALUE}.
*
* The characters in the string must all be digits of the
* specified radix (as determined by whether {@link
* java.lang.Character#digit(char, int)} returns a nonnegative
* value), except that the first character may be an ASCII plus
* sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
* integer value is returned.
*
* <p>An exception of type {@code NumberFormatException} is
* thrown if any of the following situations occurs:
* <ul>
* <li>The first argument is {@code null} or is a string of
* length zero.
*
* <li>The radix is either smaller than
* {@link java.lang.Character#MIN_RADIX} or
* larger than {@link java.lang.Character#MAX_RADIX}.
*
* <li>Any character of the string is not a digit of the specified
* radix, except that the first character may be a plus sign
* {@code '+'} ({@code '\u005Cu002B'}) provided that the
* string is longer than length 1.
*
* <li>The value represented by the string is larger than the
* largest unsigned {@code int}, 2<sup>32</sup>-1.
*
* </ul>
*
*
* @param s the {@code String} containing the unsigned integer
* representation to be parsed
* @param radix the radix to be used while parsing {@code s}.
* @return the integer represented by the string argument in the
* specified radix.
* @throws NumberFormatException if the {@code String}
* does not contain a parsable {@code int}.
* @since 1.8
*/
public static int parseUnsignedInt(String s, int radix)
throws NumberFormatException {
if (s == null) {
throw new NumberFormatException("null");
}
int len = s.length();
if (len > 0) {
char firstChar = s.charAt(0);
if (firstChar == '-') {
throw new
NumberFormatException(String.format("Illegal leading minus sign " +
"on unsigned string %s.", s));
} else {
if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
(radix == 10 && len <= 9) ) { // Integer.MAX_VALUE in base 10 is 10 digits
return parseInt(s, radix);
} else {
long ell = Long.parseLong(s, radix);
if ((ell & 0xffff_ffff_0000_0000L) == 0) {
return (int) ell;
} else {
throw new
NumberFormatException(String.format("String value %s exceeds " +
"range of unsigned int.", s));
}
}
}
} else {
throw NumberFormatException.forInputString(s, radix);
}
}
/**
* Parses the {@link CharSequence} argument as an unsigned {@code int} in
* the specified {@code radix}, beginning at the specified
* {@code beginIndex} and extending to {@code endIndex - 1}.
*
* <p>The method does not take steps to guard against the
* {@code CharSequence} being mutated while parsing.
*
* @param s the {@code CharSequence} containing the unsigned
* {@code int} representation to be parsed
* @param beginIndex the beginning index, inclusive.
* @param endIndex the ending index, exclusive.
* @param radix the radix to be used while parsing {@code s}.
* @return the unsigned {@code int} represented by the subsequence in
* the specified radix.
* @throws NullPointerException if {@code s} is null.
* @throws IndexOutOfBoundsException if {@code beginIndex} is
* negative, or if {@code beginIndex} is greater than
* {@code endIndex} or if {@code endIndex} is greater than
* {@code s.length()}.
* @throws NumberFormatException if the {@code CharSequence} does not
* contain a parsable unsigned {@code int} in the specified
* {@code radix}, or if {@code radix} is either smaller than
* {@link java.lang.Character#MIN_RADIX} or larger than
* {@link java.lang.Character#MAX_RADIX}.
* @since 9
*/
public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
throws NumberFormatException {
Objects.requireNonNull(s);
if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
throw new IndexOutOfBoundsException();
}
int start = beginIndex, len = endIndex - beginIndex;
if (len > 0) {
char firstChar = s.charAt(start);
if (firstChar == '-') {
throw new
NumberFormatException(String.format("Illegal leading minus sign " +
"on unsigned string %s.", s));
} else {
if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
(radix == 10 && len <= 9)) { // Integer.MAX_VALUE in base 10 is 10 digits
return parseInt(s, start, start + len, radix);
} else {
long ell = Long.parseLong(s, start, start + len, radix);
if ((ell & 0xffff_ffff_0000_0000L) == 0) {
return (int) ell;
} else {
throw new
NumberFormatException(String.format("String value %s exceeds " +
"range of unsigned int.", s));
}
}
}
} else {
throw new NumberFormatException("");
}
}
/**
* Parses the string argument as an unsigned decimal integer. The
* characters in the string must all be decimal digits, except
* that the first character may be an ASCII plus sign {@code
* '+'} ({@code '\u005Cu002B'}). The resulting integer value
* is returned, exactly as if the argument and the radix 10 were
* given as arguments to the {@link
* #parseUnsignedInt(java.lang.String, int)} method.
*
* @param s a {@code String} containing the unsigned {@code int}
* representation to be parsed
* @return the unsigned integer value represented by the argument in decimal.
* @throws NumberFormatException if the string does not contain a
* parsable unsigned integer.
* @since 1.8
*/
public static int parseUnsignedInt(String s) throws NumberFormatException {
return parseUnsignedInt(s, 10);
}
/**
* Returns an {@code Integer} object holding the value
* extracted from the specified {@code String} when parsed
* with the radix given by the second argument. The first argument
* is interpreted as representing a signed integer in the radix
* specified by the second argument, exactly as if the arguments
* were given to the {@link #parseInt(java.lang.String, int)}
* method. The result is an {@code Integer} object that
* represents the integer value specified by the string.
*
* <p>In other words, this method returns an {@code Integer}
* object equal to the value of:
*
* <blockquote>
* {@code new Integer(Integer.parseInt(s, radix))}
* </blockquote>
*
* @param s the string to be parsed.
* @param radix the radix to be used in interpreting {@code s}
* @return an {@code Integer} object holding the value
* represented by the string argument in the specified
* radix.
* @throws NumberFormatException if the {@code String}
* does not contain a parsable {@code int}.
*/
public static Integer valueOf(String s, int radix) throws NumberFormatException {
return Integer.valueOf(parseInt(s,radix));
}
/**
* Returns an {@code Integer} object holding the
* value of the specified {@code String}. The argument is
* interpreted as representing a signed decimal integer, exactly
* as if the argument were given to the {@link
* #parseInt(java.lang.String)} method. The result is an
* {@code Integer} object that represents the integer value
* specified by the string.
*
* <p>In other words, this method returns an {@code Integer}
* object equal to the value of:
*
* <blockquote>
* {@code new Integer(Integer.parseInt(s))}
* </blockquote>
*
* @param s the string to be parsed.
* @return an {@code Integer} object holding the value
* represented by the string argument.
* @throws NumberFormatException if the string cannot be parsed
* as an integer.
*/
public static Integer valueOf(String s) throws NumberFormatException {
return Integer.valueOf(parseInt(s, 10));
}
/**
* Cache to support the object identity semantics of autoboxing for values between
* -128 and 127 (inclusive) as required by JLS.
*
* The cache is initialized on first usage. The size of the cache
* may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
* During VM initialization, java.lang.Integer.IntegerCache.high property