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1 771 jeremybenn
/* Integer.java -- object wrapper for int
2
   Copyright (C) 1998, 1999, 2001, 2002, 2004, 2005
3
   Free Software Foundation, Inc.
4
 
5
This file is part of GNU Classpath.
6
 
7
GNU Classpath is free software; you can redistribute it and/or modify
8
it under the terms of the GNU General Public License as published by
9
the Free Software Foundation; either version 2, or (at your option)
10
any later version.
11
 
12
GNU Classpath is distributed in the hope that it will be useful, but
13
WITHOUT ANY WARRANTY; without even the implied warranty of
14
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
General Public License for more details.
16
 
17
You should have received a copy of the GNU General Public License
18
along with GNU Classpath; see the file COPYING.  If not, write to the
19
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20
02110-1301 USA.
21
 
22
Linking this library statically or dynamically with other modules is
23
making a combined work based on this library.  Thus, the terms and
24
conditions of the GNU General Public License cover the whole
25
combination.
26
 
27
As a special exception, the copyright holders of this library give you
28
permission to link this library with independent modules to produce an
29
executable, regardless of the license terms of these independent
30
modules, and to copy and distribute the resulting executable under
31
terms of your choice, provided that you also meet, for each linked
32
independent module, the terms and conditions of the license of that
33
module.  An independent module is a module which is not derived from
34
or based on this library.  If you modify this library, you may extend
35
this exception to your version of the library, but you are not
36
obligated to do so.  If you do not wish to do so, delete this
37
exception statement from your version. */
38
 
39
 
40
package java.lang;
41
 
42
/**
43
 * Instances of class <code>Integer</code> represent primitive
44
 * <code>int</code> values.
45
 *
46
 * Additionally, this class provides various helper functions and variables
47
 * related to ints.
48
 *
49
 * @author Paul Fisher
50
 * @author John Keiser
51
 * @author Warren Levy
52
 * @author Eric Blake (ebb9@email.byu.edu)
53
 * @author Tom Tromey (tromey@redhat.com)
54
 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
55
 * @author Ian Rogers
56
 * @since 1.0
57
 * @status updated to 1.5
58
 */
59
public final class Integer extends Number implements Comparable<Integer>
60
{
61
  /**
62
   * Compatible with JDK 1.0.2+.
63
   */
64
  private static final long serialVersionUID = 1360826667806852920L;
65
 
66
  /**
67
   * The minimum value an <code>int</code> can represent is -2147483648 (or
68
   * -2<sup>31</sup>).
69
   */
70
  public static final int MIN_VALUE = 0x80000000;
71
 
72
  /**
73
   * The maximum value an <code>int</code> can represent is 2147483647 (or
74
   * 2<sup>31</sup> - 1).
75
   */
76
  public static final int MAX_VALUE = 0x7fffffff;
77
 
78
  /**
79
   * The primitive type <code>int</code> is represented by this
80
   * <code>Class</code> object.
81
   * @since 1.1
82
   */
83
  public static final Class<Integer> TYPE = (Class<Integer>) VMClassLoader.getPrimitiveClass('I');
84
 
85
  /**
86
   * The number of bits needed to represent an <code>int</code>.
87
   * @since 1.5
88
   */
89
  public static final int SIZE = 32;
90
 
91
  // This caches some Integer values, and is used by boxing
92
  // conversions via valueOf().  We must cache at least -128..127;
93
  // these constants control how much we actually cache.
94
  private static final int MIN_CACHE = -128;
95
  private static final int MAX_CACHE = 127;
96
  private static final Integer[] intCache = new Integer[MAX_CACHE - MIN_CACHE + 1];
97
  static
98
  {
99
    for (int i=MIN_CACHE; i <= MAX_CACHE; i++)
100
      intCache[i - MIN_CACHE] = new Integer(i);
101
  }
102
 
103
  /**
104
   * The immutable value of this Integer.
105
   *
106
   * @serial the wrapped int
107
   */
108
  private final int value;
109
 
110
  /**
111
   * Create an <code>Integer</code> object representing the value of the
112
   * <code>int</code> argument.
113
   *
114
   * @param value the value to use
115
   */
116
  public Integer(int value)
117
  {
118
    this.value = value;
119
  }
120
 
121
  /**
122
   * Create an <code>Integer</code> object representing the value of the
123
   * argument after conversion to an <code>int</code>.
124
   *
125
   * @param s the string to convert
126
   * @throws NumberFormatException if the String does not contain an int
127
   * @see #valueOf(String)
128
   */
129
  public Integer(String s)
130
  {
131
    value = parseInt(s, 10, false);
132
  }
133
 
134
  /**
135
   * Return the size of a string large enough to hold the given number
136
   *
137
   * @param num the number we want the string length for (must be positive)
138
   * @param radix the radix (base) that will be used for the string
139
   * @return a size sufficient for a string of num
140
   */
141
  private static int stringSize(int num, int radix) {
142
    int exp;
143
    if (radix < 4)
144
      {
145
        exp = 1;
146
      }
147
    else if (radix < 8)
148
      {
149
        exp = 2;
150
      }
151
    else if (radix < 16)
152
      {
153
        exp = 3;
154
      }
155
    else if (radix < 32)
156
      {
157
        exp = 4;
158
      }
159
    else
160
      {
161
        exp = 5;
162
      }
163
    int size=0;
164
    do
165
      {
166
        num >>>= exp;
167
        size++;
168
      }
169
    while(num != 0);
170
    return size;
171
  }
172
 
173
  /**
174
   * Converts the <code>int</code> to a <code>String</code> using
175
   * the specified radix (base). If the radix exceeds
176
   * <code>Character.MIN_RADIX</code> or <code>Character.MAX_RADIX</code>, 10
177
   * is used instead. If the result is negative, the leading character is
178
   * '-' ('\\u002D'). The remaining characters come from
179
   * <code>Character.forDigit(digit, radix)</code> ('0'-'9','a'-'z').
180
   *
181
   * @param num the <code>int</code> to convert to <code>String</code>
182
   * @param radix the radix (base) to use in the conversion
183
   * @return the <code>String</code> representation of the argument
184
   */
185
  public static String toString(int num, int radix)
186
  {
187
    if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
188
      radix = 10;
189
 
190
    // Is the value negative?
191
    boolean isNeg = num < 0;
192
 
193
    // Is the string a single character?
194
    if (!isNeg && num < radix)
195
      return new String(digits, num, 1, true);
196
 
197
    // Compute string size and allocate buffer
198
    // account for a leading '-' if the value is negative
199
    int size;
200
    int i;
201
    char[] buffer;
202
    if (isNeg)
203
      {
204
        num = -num;
205
 
206
        // When the value is MIN_VALUE, it overflows when made positive
207
        if (num < 0)
208
          {
209
            i = size = stringSize(MAX_VALUE, radix) + 2;
210
            buffer = new char[size];
211
            buffer[--i] = digits[(int) (-(num + radix) % radix)];
212
            num = -(num / radix);
213
          }
214
        else
215
          {
216
            i = size = stringSize(num, radix) + 1;
217
            buffer = new char[size];
218
          }
219
      }
220
    else
221
      {
222
        i = size = stringSize(num, radix);
223
        buffer = new char[size];
224
      }
225
 
226
    do
227
      {
228
        buffer[--i] = digits[num % radix];
229
        num /= radix;
230
      }
231
    while (num > 0);
232
 
233
    if (isNeg)
234
      buffer[--i] = '-';
235
 
236
    // Package constructor avoids an array copy.
237
    return new String(buffer, i, size - i, true);
238
  }
239
 
240
  /**
241
   * Converts the <code>int</code> to a <code>String</code> assuming it is
242
   * unsigned in base 16.
243
   *
244
   * @param i the <code>int</code> to convert to <code>String</code>
245
   * @return the <code>String</code> representation of the argument
246
   */
247
  public static String toHexString(int i)
248
  {
249
    return toUnsignedString(i, 4);
250
  }
251
 
252
  /**
253
   * Converts the <code>int</code> to a <code>String</code> assuming it is
254
   * unsigned in base 8.
255
   *
256
   * @param i the <code>int</code> to convert to <code>String</code>
257
   * @return the <code>String</code> representation of the argument
258
   */
259
  public static String toOctalString(int i)
260
  {
261
    return toUnsignedString(i, 3);
262
  }
263
 
264
  /**
265
   * Converts the <code>int</code> to a <code>String</code> assuming it is
266
   * unsigned in base 2.
267
   *
268
   * @param i the <code>int</code> to convert to <code>String</code>
269
   * @return the <code>String</code> representation of the argument
270
   */
271
  public static String toBinaryString(int i)
272
  {
273
    return toUnsignedString(i, 1);
274
  }
275
 
276
  /**
277
   * Converts the <code>int</code> to a <code>String</code> and assumes
278
   * a radix of 10.
279
   *
280
   * @param i the <code>int</code> to convert to <code>String</code>
281
   * @return the <code>String</code> representation of the argument
282
   * @see #toString(int, int)
283
   */
284
  public static String toString(int i)
285
  {
286
    // This is tricky: in libgcj, String.valueOf(int) is a fast native
287
    // implementation.  In Classpath it just calls back to
288
    // Integer.toString(int, int).
289
    return String.valueOf(i);
290
  }
291
 
292
  /**
293
   * Converts the specified <code>String</code> into an <code>int</code>
294
   * using the specified radix (base). The string must not be <code>null</code>
295
   * or empty. It may begin with an optional '-', which will negate the answer,
296
   * provided that there are also valid digits. Each digit is parsed as if by
297
   * <code>Character.digit(d, radix)</code>, and must be in the range
298
   * <code>0</code> to <code>radix - 1</code>. Finally, the result must be
299
   * within <code>MIN_VALUE</code> to <code>MAX_VALUE</code>, inclusive.
300
   * Unlike Double.parseDouble, you may not have a leading '+'.
301
   *
302
   * @param str the <code>String</code> to convert
303
   * @param radix the radix (base) to use in the conversion
304
   * @return the <code>String</code> argument converted to <code>int</code>
305
   * @throws NumberFormatException if <code>s</code> cannot be parsed as an
306
   *         <code>int</code>
307
   */
308
  public static int parseInt(String str, int radix)
309
  {
310
    return parseInt(str, radix, false);
311
  }
312
 
313
  /**
314
   * Converts the specified <code>String</code> into an <code>int</code>.
315
   * This function assumes a radix of 10.
316
   *
317
   * @param s the <code>String</code> to convert
318
   * @return the <code>int</code> value of <code>s</code>
319
   * @throws NumberFormatException if <code>s</code> cannot be parsed as an
320
   *         <code>int</code>
321
   * @see #parseInt(String, int)
322
   */
323
  public static int parseInt(String s)
324
  {
325
    return parseInt(s, 10, false);
326
  }
327
 
328
  /**
329
   * Creates a new <code>Integer</code> object using the <code>String</code>
330
   * and specified radix (base).
331
   *
332
   * @param s the <code>String</code> to convert
333
   * @param radix the radix (base) to convert with
334
   * @return the new <code>Integer</code>
335
   * @throws NumberFormatException if <code>s</code> cannot be parsed as an
336
   *         <code>int</code>
337
   * @see #parseInt(String, int)
338
   */
339
  public static Integer valueOf(String s, int radix)
340
  {
341
    return valueOf(parseInt(s, radix, false));
342
  }
343
 
344
  /**
345
   * Creates a new <code>Integer</code> object using the <code>String</code>,
346
   * assuming a radix of 10.
347
   *
348
   * @param s the <code>String</code> to convert
349
   * @return the new <code>Integer</code>
350
   * @throws NumberFormatException if <code>s</code> cannot be parsed as an
351
   *         <code>int</code>
352
   * @see #Integer(String)
353
   * @see #parseInt(String)
354
   */
355
  public static Integer valueOf(String s)
356
  {
357
    return valueOf(parseInt(s, 10, false));
358
  }
359
 
360
  /**
361
   * Returns an <code>Integer</code> object wrapping the value.
362
   * In contrast to the <code>Integer</code> constructor, this method
363
   * will cache some values.  It is used by boxing conversion.
364
   *
365
   * @param val the value to wrap
366
   * @return the <code>Integer</code>
367
   */
368
  public static Integer valueOf(int val)
369
  {
370
    if (val < MIN_CACHE || val > MAX_CACHE)
371
      return new Integer(val);
372
    else
373
      return intCache[val - MIN_CACHE];
374
  }
375
 
376
  /**
377
   * Return the value of this <code>Integer</code> as a <code>byte</code>.
378
   *
379
   * @return the byte value
380
   */
381
  public byte byteValue()
382
  {
383
    return (byte) value;
384
  }
385
 
386
  /**
387
   * Return the value of this <code>Integer</code> as a <code>short</code>.
388
   *
389
   * @return the short value
390
   */
391
  public short shortValue()
392
  {
393
    return (short) value;
394
  }
395
 
396
  /**
397
   * Return the value of this <code>Integer</code>.
398
   * @return the int value
399
   */
400
  public int intValue()
401
  {
402
    return value;
403
  }
404
 
405
  /**
406
   * Return the value of this <code>Integer</code> as a <code>long</code>.
407
   *
408
   * @return the long value
409
   */
410
  public long longValue()
411
  {
412
    return value;
413
  }
414
 
415
  /**
416
   * Return the value of this <code>Integer</code> as a <code>float</code>.
417
   *
418
   * @return the float value
419
   */
420
  public float floatValue()
421
  {
422
    return value;
423
  }
424
 
425
  /**
426
   * Return the value of this <code>Integer</code> as a <code>double</code>.
427
   *
428
   * @return the double value
429
   */
430
  public double doubleValue()
431
  {
432
    return value;
433
  }
434
 
435
  /**
436
   * Converts the <code>Integer</code> value to a <code>String</code> and
437
   * assumes a radix of 10.
438
   *
439
   * @return the <code>String</code> representation
440
   */
441
  public String toString()
442
  {
443
    return String.valueOf(value);
444
  }
445
 
446
  /**
447
   * Return a hashcode representing this Object. <code>Integer</code>'s hash
448
   * code is simply its value.
449
   *
450
   * @return this Object's hash code
451
   */
452
  public int hashCode()
453
  {
454
    return value;
455
  }
456
 
457
  /**
458
   * Returns <code>true</code> if <code>obj</code> is an instance of
459
   * <code>Integer</code> and represents the same int value.
460
   *
461
   * @param obj the object to compare
462
   * @return whether these Objects are semantically equal
463
   */
464
  public boolean equals(Object obj)
465
  {
466
    return obj instanceof Integer && value == ((Integer) obj).value;
467
  }
468
 
469
  /**
470
   * Get the specified system property as an <code>Integer</code>. The
471
   * <code>decode()</code> method will be used to interpret the value of
472
   * the property.
473
   *
474
   * @param nm the name of the system property
475
   * @return the system property as an <code>Integer</code>, or null if the
476
   *         property is not found or cannot be decoded
477
   * @throws SecurityException if accessing the system property is forbidden
478
   * @see System#getProperty(String)
479
   * @see #decode(String)
480
   */
481
  public static Integer getInteger(String nm)
482
  {
483
    return getInteger(nm, null);
484
  }
485
 
486
  /**
487
   * Get the specified system property as an <code>Integer</code>, or use a
488
   * default <code>int</code> value if the property is not found or is not
489
   * decodable. The <code>decode()</code> method will be used to interpret
490
   * the value of the property.
491
   *
492
   * @param nm the name of the system property
493
   * @param val the default value
494
   * @return the value of the system property, or the default
495
   * @throws SecurityException if accessing the system property is forbidden
496
   * @see System#getProperty(String)
497
   * @see #decode(String)
498
   */
499
  public static Integer getInteger(String nm, int val)
500
  {
501
    Integer result = getInteger(nm, null);
502
    return result == null ? valueOf(val) : result;
503
  }
504
 
505
  /**
506
   * Get the specified system property as an <code>Integer</code>, or use a
507
   * default <code>Integer</code> value if the property is not found or is
508
   * not decodable. The <code>decode()</code> method will be used to
509
   * interpret the value of the property.
510
   *
511
   * @param nm the name of the system property
512
   * @param def the default value
513
   * @return the value of the system property, or the default
514
   * @throws SecurityException if accessing the system property is forbidden
515
   * @see System#getProperty(String)
516
   * @see #decode(String)
517
   */
518
  public static Integer getInteger(String nm, Integer def)
519
  {
520
    if (nm == null || "".equals(nm))
521
      return def;
522
    nm = System.getProperty(nm);
523
    if (nm == null)
524
      return def;
525
    try
526
      {
527
        return decode(nm);
528
      }
529
    catch (NumberFormatException e)
530
      {
531
        return def;
532
      }
533
  }
534
 
535
  /**
536
   * Convert the specified <code>String</code> into an <code>Integer</code>.
537
   * The <code>String</code> may represent decimal, hexadecimal, or
538
   * octal numbers.
539
   *
540
   * <p>The extended BNF grammar is as follows:<br>
541
   * <pre>
542
   * <em>DecodableString</em>:
543
   *      ( [ <code>-</code> ] <em>DecimalNumber</em> )
544
   *    | ( [ <code>-</code> ] ( <code>0x</code> | <code>0X</code>
545
   *              | <code>#</code> ) <em>HexDigit</em> { <em>HexDigit</em> } )
546
   *    | ( [ <code>-</code> ] <code>0</code> { <em>OctalDigit</em> } )
547
   * <em>DecimalNumber</em>:
548
   *        <em>DecimalDigit except '0'</em> { <em>DecimalDigit</em> }
549
   * <em>DecimalDigit</em>:
550
   *        <em>Character.digit(d, 10) has value 0 to 9</em>
551
   * <em>OctalDigit</em>:
552
   *        <em>Character.digit(d, 8) has value 0 to 7</em>
553
   * <em>DecimalDigit</em>:
554
   *        <em>Character.digit(d, 16) has value 0 to 15</em>
555
   * </pre>
556
   * Finally, the value must be in the range <code>MIN_VALUE</code> to
557
   * <code>MAX_VALUE</code>, or an exception is thrown.
558
   *
559
   * @param str the <code>String</code> to interpret
560
   * @return the value of the String as an <code>Integer</code>
561
   * @throws NumberFormatException if <code>s</code> cannot be parsed as a
562
   *         <code>int</code>
563
   * @throws NullPointerException if <code>s</code> is null
564
   * @since 1.2
565
   */
566
  public static Integer decode(String str)
567
  {
568
    return valueOf(parseInt(str, 10, true));
569
  }
570
 
571
  /**
572
   * Compare two Integers numerically by comparing their <code>int</code>
573
   * values. The result is positive if the first is greater, negative if the
574
   * second is greater, and 0 if the two are equal.
575
   *
576
   * @param i the Integer to compare
577
   * @return the comparison
578
   * @since 1.2
579
   */
580
  public int compareTo(Integer i)
581
  {
582
    if (value == i.value)
583
      return 0;
584
    // Returns just -1 or 1 on inequality; doing math might overflow.
585
    return value > i.value ? 1 : -1;
586
  }
587
 
588
  /**
589
   * Return the number of bits set in x.
590
   * @param x value to examine
591
   * @since 1.5
592
   */
593
  public static int bitCount(int x)
594
  {
595
    // Successively collapse alternating bit groups into a sum.
596
    x = ((x >> 1) & 0x55555555) + (x & 0x55555555);
597
    x = ((x >> 2) & 0x33333333) + (x & 0x33333333);
598
    x = ((x >> 4) & 0x0f0f0f0f) + (x & 0x0f0f0f0f);
599
    x = ((x >> 8) & 0x00ff00ff) + (x & 0x00ff00ff);
600
    return ((x >> 16) & 0x0000ffff) + (x & 0x0000ffff);
601
  }
602
 
603
  /**
604
   * Rotate x to the left by distance bits.
605
   * @param x the value to rotate
606
   * @param distance the number of bits by which to rotate
607
   * @since 1.5
608
   */
609
  public static int rotateLeft(int x, int distance)
610
  {
611
    // This trick works because the shift operators implicitly mask
612
    // the shift count.
613
    return (x << distance) | (x >>> - distance);
614
  }
615
 
616
  /**
617
   * Rotate x to the right by distance bits.
618
   * @param x the value to rotate
619
   * @param distance the number of bits by which to rotate
620
   * @since 1.5
621
   */
622
  public static int rotateRight(int x, int distance)
623
  {
624
    // This trick works because the shift operators implicitly mask
625
    // the shift count.
626
    return (x << - distance) | (x >>> distance);
627
  }
628
 
629
  /**
630
   * Find the highest set bit in value, and return a new value
631
   * with only that bit set.
632
   * @param value the value to examine
633
   * @since 1.5
634
   */
635
  public static int highestOneBit(int value)
636
  {
637
    value |= value >>> 1;
638
    value |= value >>> 2;
639
    value |= value >>> 4;
640
    value |= value >>> 8;
641
    value |= value >>> 16;
642
    return value ^ (value >>> 1);
643
  }
644
 
645
  /**
646
   * Return the number of leading zeros in value.
647
   * @param value the value to examine
648
   * @since 1.5
649
   */
650
  public static int numberOfLeadingZeros(int value)
651
  {
652
    value |= value >>> 1;
653
    value |= value >>> 2;
654
    value |= value >>> 4;
655
    value |= value >>> 8;
656
    value |= value >>> 16;
657
    return bitCount(~value);
658
  }
659
 
660
  /**
661
   * Find the lowest set bit in value, and return a new value
662
   * with only that bit set.
663
   * @param value the value to examine
664
   * @since 1.5
665
   */
666
  public static int lowestOneBit(int value)
667
  {
668
    // Classic assembly trick.
669
    return value & - value;
670
  }
671
 
672
  /**
673
   * Find the number of trailing zeros in value.
674
   * @param value the value to examine
675
   * @since 1.5
676
   */
677
  public static int numberOfTrailingZeros(int value)
678
  {
679
    return bitCount((value & -value) - 1);
680
  }
681
 
682
  /**
683
   * Return 1 if x is positive, -1 if it is negative, and 0 if it is
684
   * zero.
685
   * @param x the value to examine
686
   * @since 1.5
687
   */
688
  public static int signum(int x)
689
  {
690
    return (x >> 31) | (-x >>> 31);
691
 
692
    // The LHS propagates the sign bit through every bit in the word;
693
    // if X < 0, every bit is set to 1, else 0.  if X > 0, the RHS
694
    // negates x and shifts the resulting 1 in the sign bit to the
695
    // LSB, leaving every other bit 0.
696
 
697
    // Hacker's Delight, Section 2-7
698
  }
699
 
700
  /**
701
   * Reverse the bytes in val.
702
   * @since 1.5
703
   */
704
  public static int reverseBytes(int val)
705
  {
706
    return (  ((val >> 24) & 0xff)
707
            | ((val >> 8) & 0xff00)
708
            | ((val << 8) & 0xff0000)
709
            | ((val << 24) & 0xff000000));
710
  }
711
 
712
  /**
713
   * Reverse the bits in val.
714
   * @since 1.5
715
   */
716
  public static int reverse(int val)
717
  {
718
    // Successively swap alternating bit groups.
719
    val = ((val >> 1) & 0x55555555) + ((val << 1) & ~0x55555555);
720
    val = ((val >> 2) & 0x33333333) + ((val << 2) & ~0x33333333);
721
    val = ((val >> 4) & 0x0f0f0f0f) + ((val << 4) & ~0x0f0f0f0f);
722
    val = ((val >> 8) & 0x00ff00ff) + ((val << 8) & ~0x00ff00ff);
723
    return ((val >> 16) & 0x0000ffff) + ((val << 16) & ~0x0000ffff);
724
  }
725
 
726
  /**
727
   * Helper for converting unsigned numbers to String.
728
   *
729
   * @param num the number
730
   * @param exp log2(digit) (ie. 1, 3, or 4 for binary, oct, hex)
731
   */
732
  // Package visible for use by Long.
733
  static String toUnsignedString(int num, int exp)
734
  {
735
    // Compute string length
736
    int size = 1;
737
    int copy = num >>> exp;
738
    while (copy != 0)
739
      {
740
        size++;
741
        copy >>>= exp;
742
      }
743
    // Quick path for single character strings
744
    if (size == 1)
745
      return new String(digits, num, 1, true);
746
 
747
    // Encode into buffer
748
    int mask = (1 << exp) - 1;
749
    char[] buffer = new char[size];
750
    int i = size;
751
    do
752
      {
753
        buffer[--i] = digits[num & mask];
754
        num >>>= exp;
755
      }
756
    while (num != 0);
757
 
758
    // Package constructor avoids an array copy.
759
    return new String(buffer, i, size - i, true);
760
  }
761
 
762
  /**
763
   * Helper for parsing ints, used by Integer, Short, and Byte.
764
   *
765
   * @param str the string to parse
766
   * @param radix the radix to use, must be 10 if decode is true
767
   * @param decode if called from decode
768
   * @return the parsed int value
769
   * @throws NumberFormatException if there is an error
770
   * @throws NullPointerException if decode is true and str if null
771
   * @see #parseInt(String, int)
772
   * @see #decode(String)
773
   * @see Byte#parseByte(String, int)
774
   * @see Short#parseShort(String, int)
775
   */
776
  static int parseInt(String str, int radix, boolean decode)
777
  {
778
    if (! decode && str == null)
779
      throw new NumberFormatException();
780
    int index = 0;
781
    int len = str.length();
782
    boolean isNeg = false;
783
    if (len == 0)
784
      throw new NumberFormatException("string length is null");
785
    int ch = str.charAt(index);
786
    if (ch == '-')
787
      {
788
        if (len == 1)
789
          throw new NumberFormatException("pure '-'");
790
        isNeg = true;
791
        ch = str.charAt(++index);
792
      }
793
    else if (ch == '+')
794
      {
795
        if (len == 1)
796
          throw new NumberFormatException("pure '+'");
797
        ch = str.charAt(++index);
798
      }
799
    if (decode)
800
      {
801
        if (ch == '0')
802
          {
803
            if (++index == len)
804
              return 0;
805
            if ((str.charAt(index) & ~('x' ^ 'X')) == 'X')
806
              {
807
                radix = 16;
808
                index++;
809
              }
810
            else
811
              radix = 8;
812
          }
813
        else if (ch == '#')
814
          {
815
            radix = 16;
816
            index++;
817
          }
818
      }
819
    if (index == len)
820
      throw new NumberFormatException("non terminated number: " + str);
821
 
822
    int max = MAX_VALUE / radix;
823
    // We can't directly write `max = (MAX_VALUE + 1) / radix'.
824
    // So instead we fake it.
825
    if (isNeg && MAX_VALUE % radix == radix - 1)
826
      ++max;
827
 
828
    int val = 0;
829
    while (index < len)
830
      {
831
        if (val < 0 || val > max)
832
          throw new NumberFormatException("number overflow (pos=" + index + ") : " + str);
833
 
834
        ch = Character.digit(str.charAt(index++), radix);
835
        val = val * radix + ch;
836
        if (ch < 0 || (val < 0 && (! isNeg || val != MIN_VALUE)))
837
          throw new NumberFormatException("invalid character at position " + index + " in " + str);
838
      }
839
    return isNeg ? -val : val;
840
  }
841
}

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