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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

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1+/*
2+ * Copyright (c) 1994, 2010, 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.util.Properties;
29+
30+/**
31+ * The {@code Integer} class wraps a value of the primitive type
32+ * {@code int} in an object. An object of type {@code Integer}
33+ * contains a single field whose type is {@code int}.
34+ *
35+ * <p>In addition, this class provides several methods for converting
36+ * an {@code int} to a {@code String} and a {@code String} to an
37+ * {@code int}, as well as other constants and methods useful when
38+ * dealing with an {@code int}.
39+ *
40+ * <p>Implementation note: The implementations of the "bit twiddling"
41+ * methods (such as {@link #highestOneBit(int) highestOneBit} and
42+ * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
43+ * based on material from Henry S. Warren, Jr.'s <i>Hacker's
44+ * Delight</i>, (Addison Wesley, 2002).
45+ *
46+ * @author Lee Boynton
47+ * @author Arthur van Hoff
48+ * @author Josh Bloch
49+ * @author Joseph D. Darcy
50+ * @since JDK1.0
51+ */
52+public final class Integer extends Number implements Comparable<Integer> {
53+ /**
54+ * A constant holding the minimum value an {@code int} can
55+ * have, -2<sup>31</sup>.
56+ */
57+ public static final int MIN_VALUE = 0x80000000;
58+
59+ /**
60+ * A constant holding the maximum value an {@code int} can
61+ * have, 2<sup>31</sup>-1.
62+ */
63+ public static final int MAX_VALUE = 0x7fffffff;
64+
65+ /**
66+ * The {@code Class} instance representing the primitive type
67+ * {@code int}.
68+ *
69+ * @since JDK1.1
70+ */
71+ public static final Class<Integer> TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
72+
73+ /**
74+ * All possible chars for representing a number as a String
75+ */
76+ final static char[] digits = {
77+ '0' , '1' , '2' , '3' , '4' , '5' ,
78+ '6' , '7' , '8' , '9' , 'a' , 'b' ,
79+ 'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
80+ 'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
81+ 'o' , 'p' , 'q' , 'r' , 's' , 't' ,
82+ 'u' , 'v' , 'w' , 'x' , 'y' , 'z'
83+ };
84+
85+ /**
86+ * Returns a string representation of the first argument in the
87+ * radix specified by the second argument.
88+ *
89+ * <p>If the radix is smaller than {@code Character.MIN_RADIX}
90+ * or larger than {@code Character.MAX_RADIX}, then the radix
91+ * {@code 10} is used instead.
92+ *
93+ * <p>If the first argument is negative, the first element of the
94+ * result is the ASCII minus character {@code '-'}
95+ * (<code>'&#92;u002D'</code>). If the first argument is not
96+ * negative, no sign character appears in the result.
97+ *
98+ * <p>The remaining characters of the result represent the magnitude
99+ * of the first argument. If the magnitude is zero, it is
100+ * represented by a single zero character {@code '0'}
101+ * (<code>'&#92;u0030'</code>); otherwise, the first character of
102+ * the representation of the magnitude will not be the zero
103+ * character. The following ASCII characters are used as digits:
104+ *
105+ * <blockquote>
106+ * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
107+ * </blockquote>
108+ *
109+ * These are <code>'&#92;u0030'</code> through
110+ * <code>'&#92;u0039'</code> and <code>'&#92;u0061'</code> through
111+ * <code>'&#92;u007A'</code>. If {@code radix} is
112+ * <var>N</var>, then the first <var>N</var> of these characters
113+ * are used as radix-<var>N</var> digits in the order shown. Thus,
114+ * the digits for hexadecimal (radix 16) are
115+ * {@code 0123456789abcdef}. If uppercase letters are
116+ * desired, the {@link java.lang.String#toUpperCase()} method may
117+ * be called on the result:
118+ *
119+ * <blockquote>
120+ * {@code Integer.toString(n, 16).toUpperCase()}
121+ * </blockquote>
122+ *
123+ * @param i an integer to be converted to a string.
124+ * @param radix the radix to use in the string representation.
125+ * @return a string representation of the argument in the specified radix.
126+ * @see java.lang.Character#MAX_RADIX
127+ * @see java.lang.Character#MIN_RADIX
128+ */
129+ public static String toString(int i, int radix) {
130+
131+ if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
132+ radix = 10;
133+
134+ /* Use the faster version */
135+ if (radix == 10) {
136+ return toString(i);
137+ }
138+
139+ char buf[] = new char[33];
140+ boolean negative = (i < 0);
141+ int charPos = 32;
142+
143+ if (!negative) {
144+ i = -i;
145+ }
146+
147+ while (i <= -radix) {
148+ buf[charPos--] = digits[-(i % radix)];
149+ i = i / radix;
150+ }
151+ buf[charPos] = digits[-i];
152+
153+ if (negative) {
154+ buf[--charPos] = '-';
155+ }
156+
157+ return new String(buf, charPos, (33 - charPos));
158+ }
159+
160+ /**
161+ * Returns a string representation of the integer argument as an
162+ * unsigned integer in base&nbsp;16.
163+ *
164+ * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
165+ * if the argument is negative; otherwise, it is equal to the
166+ * argument. This value is converted to a string of ASCII digits
167+ * in hexadecimal (base&nbsp;16) with no extra leading
168+ * {@code 0}s. If the unsigned magnitude is zero, it is
169+ * represented by a single zero character {@code '0'}
170+ * (<code>'&#92;u0030'</code>); otherwise, the first character of
171+ * the representation of the unsigned magnitude will not be the
172+ * zero character. The following characters are used as
173+ * hexadecimal digits:
174+ *
175+ * <blockquote>
176+ * {@code 0123456789abcdef}
177+ * </blockquote>
178+ *
179+ * These are the characters <code>'&#92;u0030'</code> through
180+ * <code>'&#92;u0039'</code> and <code>'&#92;u0061'</code> through
181+ * <code>'&#92;u0066'</code>. If uppercase letters are
182+ * desired, the {@link java.lang.String#toUpperCase()} method may
183+ * be called on the result:
184+ *
185+ * <blockquote>
186+ * {@code Integer.toHexString(n).toUpperCase()}
187+ * </blockquote>
188+ *
189+ * @param i an integer to be converted to a string.
190+ * @return the string representation of the unsigned integer value
191+ * represented by the argument in hexadecimal (base&nbsp;16).
192+ * @since JDK1.0.2
193+ */
194+ public static String toHexString(int i) {
195+ return toUnsignedString(i, 4);
196+ }
197+
198+ /**
199+ * Returns a string representation of the integer argument as an
200+ * unsigned integer in base&nbsp;8.
201+ *
202+ * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
203+ * if the argument is negative; otherwise, it is equal to the
204+ * argument. This value is converted to a string of ASCII digits
205+ * in octal (base&nbsp;8) with no extra leading {@code 0}s.
206+ *
207+ * <p>If the unsigned magnitude is zero, it is represented by a
208+ * single zero character {@code '0'}
209+ * (<code>'&#92;u0030'</code>); otherwise, the first character of
210+ * the representation of the unsigned magnitude will not be the
211+ * zero character. The following characters are used as octal
212+ * digits:
213+ *
214+ * <blockquote>
215+ * {@code 01234567}
216+ * </blockquote>
217+ *
218+ * These are the characters <code>'&#92;u0030'</code> through
219+ * <code>'&#92;u0037'</code>.
220+ *
221+ * @param i an integer to be converted to a string.
222+ * @return the string representation of the unsigned integer value
223+ * represented by the argument in octal (base&nbsp;8).
224+ * @since JDK1.0.2
225+ */
226+ public static String toOctalString(int i) {
227+ return toUnsignedString(i, 3);
228+ }
229+
230+ /**
231+ * Returns a string representation of the integer argument as an
232+ * unsigned integer in base&nbsp;2.
233+ *
234+ * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
235+ * if the argument is negative; otherwise it is equal to the
236+ * argument. This value is converted to a string of ASCII digits
237+ * in binary (base&nbsp;2) with no extra leading {@code 0}s.
238+ * If the unsigned magnitude is zero, it is represented by a
239+ * single zero character {@code '0'}
240+ * (<code>'&#92;u0030'</code>); otherwise, the first character of
241+ * the representation of the unsigned magnitude will not be the
242+ * zero character. The characters {@code '0'}
243+ * (<code>'&#92;u0030'</code>) and {@code '1'}
244+ * (<code>'&#92;u0031'</code>) are used as binary digits.
245+ *
246+ * @param i an integer to be converted to a string.
247+ * @return the string representation of the unsigned integer value
248+ * represented by the argument in binary (base&nbsp;2).
249+ * @since JDK1.0.2
250+ */
251+ public static String toBinaryString(int i) {
252+ return toUnsignedString(i, 1);
253+ }
254+
255+ /**
256+ * Convert the integer to an unsigned number.
257+ */
258+ private static String toUnsignedString(int i, int shift) {
259+ char[] buf = new char[32];
260+ int charPos = 32;
261+ int radix = 1 << shift;
262+ int mask = radix - 1;
263+ do {
264+ buf[--charPos] = digits[i & mask];
265+ i >>>= shift;
266+ } while (i != 0);
267+
268+ return new String(buf, charPos, (32 - charPos));
269+ }
270+
271+
272+ final static char [] DigitTens = {
273+ '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
274+ '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
275+ '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
276+ '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
277+ '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
278+ '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
279+ '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
280+ '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
281+ '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
282+ '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
283+ } ;
284+
285+ final static char [] DigitOnes = {
286+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
287+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
288+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
289+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
290+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
291+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
292+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
293+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
294+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
295+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
296+ } ;
297+
298+ // I use the "invariant division by multiplication" trick to
299+ // accelerate Integer.toString. In particular we want to
300+ // avoid division by 10.
301+ //
302+ // The "trick" has roughly the same performance characteristics
303+ // as the "classic" Integer.toString code on a non-JIT VM.
304+ // The trick avoids .rem and .div calls but has a longer code
305+ // path and is thus dominated by dispatch overhead. In the
306+ // JIT case the dispatch overhead doesn't exist and the
307+ // "trick" is considerably faster than the classic code.
308+ //
309+ // TODO-FIXME: convert (x * 52429) into the equiv shift-add
310+ // sequence.
311+ //
312+ // RE: Division by Invariant Integers using Multiplication
313+ // T Gralund, P Montgomery
314+ // ACM PLDI 1994
315+ //
316+
317+ /**
318+ * Returns a {@code String} object representing the
319+ * specified integer. The argument is converted to signed decimal
320+ * representation and returned as a string, exactly as if the
321+ * argument and radix 10 were given as arguments to the {@link
322+ * #toString(int, int)} method.
323+ *
324+ * @param i an integer to be converted.
325+ * @return a string representation of the argument in base&nbsp;10.
326+ */
327+ public static String toString(int i) {
328+ if (i == Integer.MIN_VALUE)
329+ return "-2147483648";
330+ int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
331+ char[] buf = new char[size];
332+ getChars(i, size, buf);
333+ return new String(0, size, buf);
334+ }
335+
336+ /**
337+ * Places characters representing the integer i into the
338+ * character array buf. The characters are placed into
339+ * the buffer backwards starting with the least significant
340+ * digit at the specified index (exclusive), and working
341+ * backwards from there.
342+ *
343+ * Will fail if i == Integer.MIN_VALUE
344+ */
345+ static void getChars(int i, int index, char[] buf) {
346+ int q, r;
347+ int charPos = index;
348+ char sign = 0;
349+
350+ if (i < 0) {
351+ sign = '-';
352+ i = -i;
353+ }
354+
355+ // Generate two digits per iteration
356+ while (i >= 65536) {
357+ q = i / 100;
358+ // really: r = i - (q * 100);
359+ r = i - ((q << 6) + (q << 5) + (q << 2));
360+ i = q;
361+ buf [--charPos] = DigitOnes[r];
362+ buf [--charPos] = DigitTens[r];
363+ }
364+
365+ // Fall thru to fast mode for smaller numbers
366+ // assert(i <= 65536, i);
367+ for (;;) {
368+ q = (i * 52429) >>> (16+3);
369+ r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
370+ buf [--charPos] = digits [r];
371+ i = q;
372+ if (i == 0) break;
373+ }
374+ if (sign != 0) {
375+ buf [--charPos] = sign;
376+ }
377+ }
378+
379+ final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
380+ 99999999, 999999999, Integer.MAX_VALUE };
381+
382+ // Requires positive x
383+ static int stringSize(int x) {
384+ for (int i=0; ; i++)
385+ if (x <= sizeTable[i])
386+ return i+1;
387+ }
388+
389+ /**
390+ * Parses the string argument as a signed integer in the radix
391+ * specified by the second argument. The characters in the string
392+ * must all be digits of the specified radix (as determined by
393+ * whether {@link java.lang.Character#digit(char, int)} returns a
394+ * nonnegative value), except that the first character may be an
395+ * ASCII minus sign {@code '-'} (<code>'&#92;u002D'</code>) to
396+ * indicate a negative value or an ASCII plus sign {@code '+'}
397+ * (<code>'&#92;u002B'</code>) to indicate a positive value. The
398+ * resulting integer value is returned.
399+ *
400+ * <p>An exception of type {@code NumberFormatException} is
401+ * thrown if any of the following situations occurs:
402+ * <ul>
403+ * <li>The first argument is {@code null} or is a string of
404+ * length zero.
405+ *
406+ * <li>The radix is either smaller than
407+ * {@link java.lang.Character#MIN_RADIX} or
408+ * larger than {@link java.lang.Character#MAX_RADIX}.
409+ *
410+ * <li>Any character of the string is not a digit of the specified
411+ * radix, except that the first character may be a minus sign
412+ * {@code '-'} (<code>'&#92;u002D'</code>) or plus sign
413+ * {@code '+'} (<code>'&#92;u002B'</code>) provided that the
414+ * string is longer than length 1.
415+ *
416+ * <li>The value represented by the string is not a value of type
417+ * {@code int}.
418+ * </ul>
419+ *
420+ * <p>Examples:
421+ * <blockquote><pre>
422+ * parseInt("0", 10) returns 0
423+ * parseInt("473", 10) returns 473
424+ * parseInt("+42", 10) returns 42
425+ * parseInt("-0", 10) returns 0
426+ * parseInt("-FF", 16) returns -255
427+ * parseInt("1100110", 2) returns 102
428+ * parseInt("2147483647", 10) returns 2147483647
429+ * parseInt("-2147483648", 10) returns -2147483648
430+ * parseInt("2147483648", 10) throws a NumberFormatException
431+ * parseInt("99", 8) throws a NumberFormatException
432+ * parseInt("Kona", 10) throws a NumberFormatException
433+ * parseInt("Kona", 27) returns 411787
434+ * </pre></blockquote>
435+ *
436+ * @param s the {@code String} containing the integer
437+ * representation to be parsed
438+ * @param radix the radix to be used while parsing {@code s}.
439+ * @return the integer represented by the string argument in the
440+ * specified radix.
441+ * @exception NumberFormatException if the {@code String}
442+ * does not contain a parsable {@code int}.
443+ */
444+ public static int parseInt(String s, int radix)
445+ throws NumberFormatException
446+ {
447+ /*
448+ * WARNING: This method may be invoked early during VM initialization
449+ * before IntegerCache is initialized. Care must be taken to not use
450+ * the valueOf method.
451+ */
452+
453+ if (s == null) {
454+ throw new NumberFormatException("null");
455+ }
456+
457+ if (radix < Character.MIN_RADIX) {
458+ throw new NumberFormatException("radix " + radix +
459+ " less than Character.MIN_RADIX");
460+ }
461+
462+ if (radix > Character.MAX_RADIX) {
463+ throw new NumberFormatException("radix " + radix +
464+ " greater than Character.MAX_RADIX");
465+ }
466+
467+ int result = 0;
468+ boolean negative = false;
469+ int i = 0, len = s.length();
470+ int limit = -Integer.MAX_VALUE;
471+ int multmin;
472+ int digit;
473+
474+ if (len > 0) {
475+ char firstChar = s.charAt(0);
476+ if (firstChar < '0') { // Possible leading "+" or "-"
477+ if (firstChar == '-') {
478+ negative = true;
479+ limit = Integer.MIN_VALUE;
480+ } else if (firstChar != '+')
481+ throw NumberFormatException.forInputString(s);
482+
483+ if (len == 1) // Cannot have lone "+" or "-"
484+ throw NumberFormatException.forInputString(s);
485+ i++;
486+ }
487+ multmin = limit / radix;
488+ while (i < len) {
489+ // Accumulating negatively avoids surprises near MAX_VALUE
490+ digit = Character.digit(s.charAt(i++),radix);
491+ if (digit < 0) {
492+ throw NumberFormatException.forInputString(s);
493+ }
494+ if (result < multmin) {
495+ throw NumberFormatException.forInputString(s);
496+ }
497+ result *= radix;
498+ if (result < limit + digit) {
499+ throw NumberFormatException.forInputString(s);
500+ }
501+ result -= digit;
502+ }
503+ } else {
504+ throw NumberFormatException.forInputString(s);
505+ }
506+ return negative ? result : -result;
507+ }
508+
509+ /**
510+ * Parses the string argument as a signed decimal integer. The
511+ * characters in the string must all be decimal digits, except
512+ * that the first character may be an ASCII minus sign {@code '-'}
513+ * (<code>'&#92;u002D'</code>) to indicate a negative value or an
514+ * ASCII plus sign {@code '+'} (<code>'&#92;u002B'</code>) to
515+ * indicate a positive value. The resulting integer value is
516+ * returned, exactly as if the argument and the radix 10 were
517+ * given as arguments to the {@link #parseInt(java.lang.String,
518+ * int)} method.
519+ *
520+ * @param s a {@code String} containing the {@code int}
521+ * representation to be parsed
522+ * @return the integer value represented by the argument in decimal.
523+ * @exception NumberFormatException if the string does not contain a
524+ * parsable integer.
525+ */
526+ public static int parseInt(String s) throws NumberFormatException {
527+ return parseInt(s,10);
528+ }
529+
530+ /**
531+ * Returns an {@code Integer} object holding the value
532+ * extracted from the specified {@code String} when parsed
533+ * with the radix given by the second argument. The first argument
534+ * is interpreted as representing a signed integer in the radix
535+ * specified by the second argument, exactly as if the arguments
536+ * were given to the {@link #parseInt(java.lang.String, int)}
537+ * method. The result is an {@code Integer} object that
538+ * represents the integer value specified by the string.
539+ *
540+ * <p>In other words, this method returns an {@code Integer}
541+ * object equal to the value of:
542+ *
543+ * <blockquote>
544+ * {@code new Integer(Integer.parseInt(s, radix))}
545+ * </blockquote>
546+ *
547+ * @param s the string to be parsed.
548+ * @param radix the radix to be used in interpreting {@code s}
549+ * @return an {@code Integer} object holding the value
550+ * represented by the string argument in the specified
551+ * radix.
552+ * @exception NumberFormatException if the {@code String}
553+ * does not contain a parsable {@code int}.
554+ */
555+ public static Integer valueOf(String s, int radix) throws NumberFormatException {
556+ return Integer.valueOf(parseInt(s,radix));
557+ }
558+
559+ /**
560+ * Returns an {@code Integer} object holding the
561+ * value of the specified {@code String}. The argument is
562+ * interpreted as representing a signed decimal integer, exactly
563+ * as if the argument were given to the {@link
564+ * #parseInt(java.lang.String)} method. The result is an
565+ * {@code Integer} object that represents the integer value
566+ * specified by the string.
567+ *
568+ * <p>In other words, this method returns an {@code Integer}
569+ * object equal to the value of:
570+ *
571+ * <blockquote>
572+ * {@code new Integer(Integer.parseInt(s))}
573+ * </blockquote>
574+ *
575+ * @param s the string to be parsed.
576+ * @return an {@code Integer} object holding the value
577+ * represented by the string argument.
578+ * @exception NumberFormatException if the string cannot be parsed
579+ * as an integer.
580+ */
581+ public static Integer valueOf(String s) throws NumberFormatException {
582+ return Integer.valueOf(parseInt(s, 10));
583+ }
584+
585+ /**
586+ * Cache to support the object identity semantics of autoboxing for values between
587+ * -128 and 127 (inclusive) as required by JLS.
588+ *
589+ * The cache is initialized on first usage. The size of the cache
590+ * may be controlled by the -XX:AutoBoxCacheMax=<size> option.
591+ * During VM initialization, java.lang.Integer.IntegerCache.high property
592+ * may be set and saved in the private system properties in the
593+ * sun.misc.VM class.
594+ */
595+
596+ private static class IntegerCache {
597+ static final int low = -128;
598+ static final int high;
599+ static final Integer cache[];
600+
601+ static {
602+ // high value may be configured by property
603+ int h = 127;
604+ String integerCacheHighPropValue =
605+ sun.misc.VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
606+ if (integerCacheHighPropValue != null) {
607+ int i = parseInt(integerCacheHighPropValue);
608+ i = Math.max(i, 127);
609+ // Maximum array size is Integer.MAX_VALUE
610+ h = Math.min(i, Integer.MAX_VALUE - (-low));
611+ }
612+ high = h;
613+
614+ cache = new Integer[(high - low) + 1];
615+ int j = low;
616+ for(int k = 0; k < cache.length; k++)
617+ cache[k] = new Integer(j++);
618+ }
619+
620+ private IntegerCache() {}
621+ }
622+
623+ /**
624+ * Returns an {@code Integer} instance representing the specified
625+ * {@code int} value. If a new {@code Integer} instance is not
626+ * required, this method should generally be used in preference to
627+ * the constructor {@link #Integer(int)}, as this method is likely
628+ * to yield significantly better space and time performance by
629+ * caching frequently requested values.
630+ *
631+ * This method will always cache values in the range -128 to 127,
632+ * inclusive, and may cache other values outside of this range.
633+ *
634+ * @param i an {@code int} value.
635+ * @return an {@code Integer} instance representing {@code i}.
636+ * @since 1.5
637+ */
638+ public static Integer valueOf(int i) {
639+ assert IntegerCache.high >= 127;
640+ if (i >= IntegerCache.low && i <= IntegerCache.high)
641+ return IntegerCache.cache[i + (-IntegerCache.low)];
642+ return new Integer(i);
643+ }
644+
645+ /**
646+ * The value of the {@code Integer}.
647+ *
648+ * @serial
649+ */
650+ private final int value;
651+
652+ /**
653+ * Constructs a newly allocated {@code Integer} object that
654+ * represents the specified {@code int} value.
655+ *
656+ * @param value the value to be represented by the
657+ * {@code Integer} object.
658+ */
659+ public Integer(int value) {
660+ this.value = value;
661+ }
662+
663+ /**
664+ * Constructs a newly allocated {@code Integer} object that
665+ * represents the {@code int} value indicated by the
666+ * {@code String} parameter. The string is converted to an
667+ * {@code int} value in exactly the manner used by the
668+ * {@code parseInt} method for radix 10.
669+ *
670+ * @param s the {@code String} to be converted to an
671+ * {@code Integer}.
672+ * @exception NumberFormatException if the {@code String} does not
673+ * contain a parsable integer.
674+ * @see java.lang.Integer#parseInt(java.lang.String, int)
675+ */
676+ public Integer(String s) throws NumberFormatException {
677+ this.value = parseInt(s, 10);
678+ }
679+
680+ /**
681+ * Returns the value of this {@code Integer} as a
682+ * {@code byte}.
683+ */
684+ public byte byteValue() {
685+ return (byte)value;
686+ }
687+
688+ /**
689+ * Returns the value of this {@code Integer} as a
690+ * {@code short}.
691+ */
692+ public short shortValue() {
693+ return (short)value;
694+ }
695+
696+ /**
697+ * Returns the value of this {@code Integer} as an
698+ * {@code int}.
699+ */
700+ public int intValue() {
701+ return value;
702+ }
703+
704+ /**
705+ * Returns the value of this {@code Integer} as a
706+ * {@code long}.
707+ */
708+ public long longValue() {
709+ return (long)value;
710+ }
711+
712+ /**
713+ * Returns the value of this {@code Integer} as a
714+ * {@code float}.
715+ */
716+ public float floatValue() {
717+ return (float)value;
718+ }
719+
720+ /**
721+ * Returns the value of this {@code Integer} as a
722+ * {@code double}.
723+ */
724+ public double doubleValue() {
725+ return (double)value;
726+ }
727+
728+ /**
729+ * Returns a {@code String} object representing this
730+ * {@code Integer}'s value. The value is converted to signed
731+ * decimal representation and returned as a string, exactly as if
732+ * the integer value were given as an argument to the {@link
733+ * java.lang.Integer#toString(int)} method.
734+ *
735+ * @return a string representation of the value of this object in
736+ * base&nbsp;10.
737+ */
738+ public String toString() {
739+ return toString(value);
740+ }
741+
742+ /**
743+ * Returns a hash code for this {@code Integer}.
744+ *
745+ * @return a hash code value for this object, equal to the
746+ * primitive {@code int} value represented by this
747+ * {@code Integer} object.
748+ */
749+ public int hashCode() {
750+ return value;
751+ }
752+
753+ /**
754+ * Compares this object to the specified object. The result is
755+ * {@code true} if and only if the argument is not
756+ * {@code null} and is an {@code Integer} object that
757+ * contains the same {@code int} value as this object.
758+ *
759+ * @param obj the object to compare with.
760+ * @return {@code true} if the objects are the same;
761+ * {@code false} otherwise.
762+ */
763+ public boolean equals(Object obj) {
764+ if (obj instanceof Integer) {
765+ return value == ((Integer)obj).intValue();
766+ }
767+ return false;
768+ }
769+
770+ /**
771+ * Determines the integer value of the system property with the
772+ * specified name.
773+ *
774+ * <p>The first argument is treated as the name of a system property.
775+ * System properties are accessible through the
776+ * {@link java.lang.System#getProperty(java.lang.String)} method. The
777+ * string value of this property is then interpreted as an integer
778+ * value and an {@code Integer} object representing this value is
779+ * returned. Details of possible numeric formats can be found with
780+ * the definition of {@code getProperty}.
781+ *
782+ * <p>If there is no property with the specified name, if the specified name
783+ * is empty or {@code null}, or if the property does not have
784+ * the correct numeric format, then {@code null} is returned.
785+ *
786+ * <p>In other words, this method returns an {@code Integer}
787+ * object equal to the value of:
788+ *
789+ * <blockquote>
790+ * {@code getInteger(nm, null)}
791+ * </blockquote>
792+ *
793+ * @param nm property name.
794+ * @return the {@code Integer} value of the property.
795+ * @see java.lang.System#getProperty(java.lang.String)
796+ * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
797+ */
798+ public static Integer getInteger(String nm) {
799+ return getInteger(nm, null);
800+ }
801+
802+ /**
803+ * Determines the integer value of the system property with the
804+ * specified name.
805+ *
806+ * <p>The first argument is treated as the name of a system property.
807+ * System properties are accessible through the {@link
808+ * java.lang.System#getProperty(java.lang.String)} method. The
809+ * string value of this property is then interpreted as an integer
810+ * value and an {@code Integer} object representing this value is
811+ * returned. Details of possible numeric formats can be found with
812+ * the definition of {@code getProperty}.
813+ *
814+ * <p>The second argument is the default value. An {@code Integer} object
815+ * that represents the value of the second argument is returned if there
816+ * is no property of the specified name, if the property does not have
817+ * the correct numeric format, or if the specified name is empty or
818+ * {@code null}.
819+ *
820+ * <p>In other words, this method returns an {@code Integer} object
821+ * equal to the value of:
822+ *
823+ * <blockquote>
824+ * {@code getInteger(nm, new Integer(val))}
825+ * </blockquote>
826+ *
827+ * but in practice it may be implemented in a manner such as:
828+ *
829+ * <blockquote><pre>
830+ * Integer result = getInteger(nm, null);
831+ * return (result == null) ? new Integer(val) : result;
832+ * </pre></blockquote>
833+ *
834+ * to avoid the unnecessary allocation of an {@code Integer}
835+ * object when the default value is not needed.
836+ *
837+ * @param nm property name.
838+ * @param val default value.
839+ * @return the {@code Integer} value of the property.
840+ * @see java.lang.System#getProperty(java.lang.String)
841+ * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
842+ */
843+ public static Integer getInteger(String nm, int val) {
844+ Integer result = getInteger(nm, null);
845+ return (result == null) ? Integer.valueOf(val) : result;
846+ }
847+
848+ /**
849+ * Returns the integer value of the system property with the
850+ * specified name. The first argument is treated as the name of a
851+ * system property. System properties are accessible through the
852+ * {@link java.lang.System#getProperty(java.lang.String)} method.
853+ * The string value of this property is then interpreted as an
854+ * integer value, as per the {@code Integer.decode} method,
855+ * and an {@code Integer} object representing this value is
856+ * returned.
857+ *
858+ * <ul><li>If the property value begins with the two ASCII characters
859+ * {@code 0x} or the ASCII character {@code #}, not
860+ * followed by a minus sign, then the rest of it is parsed as a
861+ * hexadecimal integer exactly as by the method
862+ * {@link #valueOf(java.lang.String, int)} with radix 16.
863+ * <li>If the property value begins with the ASCII character
864+ * {@code 0} followed by another character, it is parsed as an
865+ * octal integer exactly as by the method
866+ * {@link #valueOf(java.lang.String, int)} with radix 8.
867+ * <li>Otherwise, the property value is parsed as a decimal integer
868+ * exactly as by the method {@link #valueOf(java.lang.String, int)}
869+ * with radix 10.
870+ * </ul>
871+ *
872+ * <p>The second argument is the default value. The default value is
873+ * returned if there is no property of the specified name, if the
874+ * property does not have the correct numeric format, or if the
875+ * specified name is empty or {@code null}.
876+ *
877+ * @param nm property name.
878+ * @param val default value.
879+ * @return the {@code Integer} value of the property.
880+ * @see java.lang.System#getProperty(java.lang.String)
881+ * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
882+ * @see java.lang.Integer#decode
883+ */
884+ public static Integer getInteger(String nm, Integer val) {
885+ String v = null;
886+ try {
887+ v = System.getProperty(nm);
888+ } catch (IllegalArgumentException e) {
889+ } catch (NullPointerException e) {
890+ }
891+ if (v != null) {
892+ try {
893+ return Integer.decode(v);
894+ } catch (NumberFormatException e) {
895+ }
896+ }
897+ return val;
898+ }
899+
900+ /**
901+ * Decodes a {@code String} into an {@code Integer}.
902+ * Accepts decimal, hexadecimal, and octal numbers given
903+ * by the following grammar:
904+ *
905+ * <blockquote>
906+ * <dl>
907+ * <dt><i>DecodableString:</i>
908+ * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
909+ * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
910+ * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
911+ * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
912+ * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
913+ * <p>
914+ * <dt><i>Sign:</i>
915+ * <dd>{@code -}
916+ * <dd>{@code +}
917+ * </dl>
918+ * </blockquote>
919+ *
920+ * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
921+ * are as defined in section 3.10.1 of
922+ * <cite>The Java&trade; Language Specification</cite>,
923+ * except that underscores are not accepted between digits.
924+ *
925+ * <p>The sequence of characters following an optional
926+ * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
927+ * "{@code #}", or leading zero) is parsed as by the {@code
928+ * Integer.parseInt} method with the indicated radix (10, 16, or
929+ * 8). This sequence of characters must represent a positive
930+ * value or a {@link NumberFormatException} will be thrown. The
931+ * result is negated if first character of the specified {@code
932+ * String} is the minus sign. No whitespace characters are
933+ * permitted in the {@code String}.
934+ *
935+ * @param nm the {@code String} to decode.
936+ * @return an {@code Integer} object holding the {@code int}
937+ * value represented by {@code nm}
938+ * @exception NumberFormatException if the {@code String} does not
939+ * contain a parsable integer.
940+ * @see java.lang.Integer#parseInt(java.lang.String, int)
941+ */
942+ public static Integer decode(String nm) throws NumberFormatException {
943+ int radix = 10;
944+ int index = 0;
945+ boolean negative = false;
946+ Integer result;
947+
948+ if (nm.length() == 0)
949+ throw new NumberFormatException("Zero length string");
950+ char firstChar = nm.charAt(0);
951+ // Handle sign, if present
952+ if (firstChar == '-') {
953+ negative = true;
954+ index++;
955+ } else if (firstChar == '+')
956+ index++;
957+
958+ // Handle radix specifier, if present
959+ if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
960+ index += 2;
961+ radix = 16;
962+ }
963+ else if (nm.startsWith("#", index)) {
964+ index ++;
965+ radix = 16;
966+ }
967+ else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
968+ index ++;
969+ radix = 8;
970+ }
971+
972+ if (nm.startsWith("-", index) || nm.startsWith("+", index))
973+ throw new NumberFormatException("Sign character in wrong position");
974+
975+ try {
976+ result = Integer.valueOf(nm.substring(index), radix);
977+ result = negative ? Integer.valueOf(-result.intValue()) : result;
978+ } catch (NumberFormatException e) {
979+ // If number is Integer.MIN_VALUE, we'll end up here. The next line
980+ // handles this case, and causes any genuine format error to be
981+ // rethrown.
982+ String constant = negative ? ("-" + nm.substring(index))
983+ : nm.substring(index);
984+ result = Integer.valueOf(constant, radix);
985+ }
986+ return result;
987+ }
988+
989+ /**
990+ * Compares two {@code Integer} objects numerically.
991+ *
992+ * @param anotherInteger the {@code Integer} to be compared.
993+ * @return the value {@code 0} if this {@code Integer} is
994+ * equal to the argument {@code Integer}; a value less than
995+ * {@code 0} if this {@code Integer} is numerically less
996+ * than the argument {@code Integer}; and a value greater
997+ * than {@code 0} if this {@code Integer} is numerically
998+ * greater than the argument {@code Integer} (signed
999+ * comparison).
1000+ * @since 1.2
1001+ */
1002+ public int compareTo(Integer anotherInteger) {
1003+ return compare(this.value, anotherInteger.value);
1004+ }
1005+
1006+ /**
1007+ * Compares two {@code int} values numerically.
1008+ * The value returned is identical to what would be returned by:
1009+ * <pre>
1010+ * Integer.valueOf(x).compareTo(Integer.valueOf(y))
1011+ * </pre>
1012+ *
1013+ * @param x the first {@code int} to compare
1014+ * @param y the second {@code int} to compare
1015+ * @return the value {@code 0} if {@code x == y};
1016+ * a value less than {@code 0} if {@code x < y}; and
1017+ * a value greater than {@code 0} if {@code x > y}
1018+ * @since 1.7
1019+ */
1020+ public static int compare(int x, int y) {
1021+ return (x < y) ? -1 : ((x == y) ? 0 : 1);
1022+ }
1023+
1024+
1025+ // Bit twiddling
1026+
1027+ /**
1028+ * The number of bits used to represent an {@code int} value in two's
1029+ * complement binary form.
1030+ *
1031+ * @since 1.5
1032+ */
1033+ public static final int SIZE = 32;
1034+
1035+ /**
1036+ * Returns an {@code int} value with at most a single one-bit, in the
1037+ * position of the highest-order ("leftmost") one-bit in the specified
1038+ * {@code int} value. Returns zero if the specified value has no
1039+ * one-bits in its two's complement binary representation, that is, if it
1040+ * is equal to zero.
1041+ *
1042+ * @return an {@code int} value with a single one-bit, in the position
1043+ * of the highest-order one-bit in the specified value, or zero if
1044+ * the specified value is itself equal to zero.
1045+ * @since 1.5
1046+ */
1047+ public static int highestOneBit(int i) {
1048+ // HD, Figure 3-1
1049+ i |= (i >> 1);
1050+ i |= (i >> 2);
1051+ i |= (i >> 4);
1052+ i |= (i >> 8);
1053+ i |= (i >> 16);
1054+ return i - (i >>> 1);
1055+ }
1056+
1057+ /**
1058+ * Returns an {@code int} value with at most a single one-bit, in the
1059+ * position of the lowest-order ("rightmost") one-bit in the specified
1060+ * {@code int} value. Returns zero if the specified value has no
1061+ * one-bits in its two's complement binary representation, that is, if it
1062+ * is equal to zero.
1063+ *
1064+ * @return an {@code int} value with a single one-bit, in the position
1065+ * of the lowest-order one-bit in the specified value, or zero if
1066+ * the specified value is itself equal to zero.
1067+ * @since 1.5
1068+ */
1069+ public static int lowestOneBit(int i) {
1070+ // HD, Section 2-1
1071+ return i & -i;
1072+ }
1073+
1074+ /**
1075+ * Returns the number of zero bits preceding the highest-order
1076+ * ("leftmost") one-bit in the two's complement binary representation
1077+ * of the specified {@code int} value. Returns 32 if the
1078+ * specified value has no one-bits in its two's complement representation,
1079+ * in other words if it is equal to zero.
1080+ *
1081+ * <p>Note that this method is closely related to the logarithm base 2.
1082+ * For all positive {@code int} values x:
1083+ * <ul>
1084+ * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1085+ * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1086+ * </ul>
1087+ *
1088+ * @return the number of zero bits preceding the highest-order
1089+ * ("leftmost") one-bit in the two's complement binary representation
1090+ * of the specified {@code int} value, or 32 if the value
1091+ * is equal to zero.
1092+ * @since 1.5
1093+ */
1094+ public static int numberOfLeadingZeros(int i) {
1095+ // HD, Figure 5-6
1096+ if (i == 0)
1097+ return 32;
1098+ int n = 1;
1099+ if (i >>> 16 == 0) { n += 16; i <<= 16; }
1100+ if (i >>> 24 == 0) { n += 8; i <<= 8; }
1101+ if (i >>> 28 == 0) { n += 4; i <<= 4; }
1102+ if (i >>> 30 == 0) { n += 2; i <<= 2; }
1103+ n -= i >>> 31;
1104+ return n;
1105+ }
1106+
1107+ /**
1108+ * Returns the number of zero bits following the lowest-order ("rightmost")
1109+ * one-bit in the two's complement binary representation of the specified
1110+ * {@code int} value. Returns 32 if the specified value has no
1111+ * one-bits in its two's complement representation, in other words if it is
1112+ * equal to zero.
1113+ *
1114+ * @return the number of zero bits following the lowest-order ("rightmost")
1115+ * one-bit in the two's complement binary representation of the
1116+ * specified {@code int} value, or 32 if the value is equal
1117+ * to zero.
1118+ * @since 1.5
1119+ */
1120+ public static int numberOfTrailingZeros(int i) {
1121+ // HD, Figure 5-14
1122+ int y;
1123+ if (i == 0) return 32;
1124+ int n = 31;
1125+ y = i <<16; if (y != 0) { n = n -16; i = y; }
1126+ y = i << 8; if (y != 0) { n = n - 8; i = y; }
1127+ y = i << 4; if (y != 0) { n = n - 4; i = y; }
1128+ y = i << 2; if (y != 0) { n = n - 2; i = y; }
1129+ return n - ((i << 1) >>> 31);
1130+ }
1131+
1132+ /**
1133+ * Returns the number of one-bits in the two's complement binary
1134+ * representation of the specified {@code int} value. This function is
1135+ * sometimes referred to as the <i>population count</i>.
1136+ *
1137+ * @return the number of one-bits in the two's complement binary
1138+ * representation of the specified {@code int} value.
1139+ * @since 1.5
1140+ */
1141+ public static int bitCount(int i) {
1142+ // HD, Figure 5-2
1143+ i = i - ((i >>> 1) & 0x55555555);
1144+ i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1145+ i = (i + (i >>> 4)) & 0x0f0f0f0f;
1146+ i = i + (i >>> 8);
1147+ i = i + (i >>> 16);
1148+ return i & 0x3f;
1149+ }
1150+
1151+ /**
1152+ * Returns the value obtained by rotating the two's complement binary
1153+ * representation of the specified {@code int} value left by the
1154+ * specified number of bits. (Bits shifted out of the left hand, or
1155+ * high-order, side reenter on the right, or low-order.)
1156+ *
1157+ * <p>Note that left rotation with a negative distance is equivalent to
1158+ * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1159+ * distance)}. Note also that rotation by any multiple of 32 is a
1160+ * no-op, so all but the last five bits of the rotation distance can be
1161+ * ignored, even if the distance is negative: {@code rotateLeft(val,
1162+ * distance) == rotateLeft(val, distance & 0x1F)}.
1163+ *
1164+ * @return the value obtained by rotating the two's complement binary
1165+ * representation of the specified {@code int} value left by the
1166+ * specified number of bits.
1167+ * @since 1.5
1168+ */
1169+ public static int rotateLeft(int i, int distance) {
1170+ return (i << distance) | (i >>> -distance);
1171+ }
1172+
1173+ /**
1174+ * Returns the value obtained by rotating the two's complement binary
1175+ * representation of the specified {@code int} value right by the
1176+ * specified number of bits. (Bits shifted out of the right hand, or
1177+ * low-order, side reenter on the left, or high-order.)
1178+ *
1179+ * <p>Note that right rotation with a negative distance is equivalent to
1180+ * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1181+ * distance)}. Note also that rotation by any multiple of 32 is a
1182+ * no-op, so all but the last five bits of the rotation distance can be
1183+ * ignored, even if the distance is negative: {@code rotateRight(val,
1184+ * distance) == rotateRight(val, distance & 0x1F)}.
1185+ *
1186+ * @return the value obtained by rotating the two's complement binary
1187+ * representation of the specified {@code int} value right by the
1188+ * specified number of bits.
1189+ * @since 1.5
1190+ */
1191+ public static int rotateRight(int i, int distance) {
1192+ return (i >>> distance) | (i << -distance);
1193+ }
1194+
1195+ /**
1196+ * Returns the value obtained by reversing the order of the bits in the
1197+ * two's complement binary representation of the specified {@code int}
1198+ * value.
1199+ *
1200+ * @return the value obtained by reversing order of the bits in the
1201+ * specified {@code int} value.
1202+ * @since 1.5
1203+ */
1204+ public static int reverse(int i) {
1205+ // HD, Figure 7-1
1206+ i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1207+ i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1208+ i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1209+ i = (i << 24) | ((i & 0xff00) << 8) |
1210+ ((i >>> 8) & 0xff00) | (i >>> 24);
1211+ return i;
1212+ }
1213+
1214+ /**
1215+ * Returns the signum function of the specified {@code int} value. (The
1216+ * return value is -1 if the specified value is negative; 0 if the
1217+ * specified value is zero; and 1 if the specified value is positive.)
1218+ *
1219+ * @return the signum function of the specified {@code int} value.
1220+ * @since 1.5
1221+ */
1222+ public static int signum(int i) {
1223+ // HD, Section 2-7
1224+ return (i >> 31) | (-i >>> 31);
1225+ }
1226+
1227+ /**
1228+ * Returns the value obtained by reversing the order of the bytes in the
1229+ * two's complement representation of the specified {@code int} value.
1230+ *
1231+ * @return the value obtained by reversing the bytes in the specified
1232+ * {@code int} value.
1233+ * @since 1.5
1234+ */
1235+ public static int reverseBytes(int i) {
1236+ return ((i >>> 24) ) |
1237+ ((i >> 8) & 0xFF00) |
1238+ ((i << 8) & 0xFF0000) |
1239+ ((i << 24));
1240+ }
1241+
1242+ /** use serialVersionUID from JDK 1.0.2 for interoperability */
1243+ private static final long serialVersionUID = 1360826667806852920L;
1244+}