0001 /*
0002 * Copyright 1994-2006 Sun Microsystems, Inc. All Rights Reserved.
0003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
0004 *
0005 * This code is free software; you can redistribute it and/or modify it
0006 * under the terms of the GNU General Public License version 2 only, as
0007 * published by the Free Software Foundation. Sun designates this
0008 * particular file as subject to the "Classpath" exception as provided
0009 * by Sun in the LICENSE file that accompanied this code.
0010 *
0011 * This code is distributed in the hope that it will be useful, but WITHOUT
0012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0014 * version 2 for more details (a copy is included in the LICENSE file that
0015 * accompanied this code).
0016 *
0017 * You should have received a copy of the GNU General Public License version
0018 * 2 along with this work; if not, write to the Free Software Foundation,
0019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
0020 *
0021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
0022 * CA 95054 USA or visit www.sun.com if you need additional information or
0023 * have any questions.
0024 */
0025
0026 package java.lang;
0027
0028 /**
0029 * The {@code Integer} class wraps a value of the primitive type
0030 * {@code int} in an object. An object of type {@code Integer}
0031 * contains a single field whose type is {@code int}.
0032 *
0033 * <p>In addition, this class provides several methods for converting
0034 * an {@code int} to a {@code String} and a {@code String} to an
0035 * {@code int}, as well as other constants and methods useful when
0036 * dealing with an {@code int}.
0037 *
0038 * <p>Implementation note: The implementations of the "bit twiddling"
0039 * methods (such as {@link #highestOneBit(int) highestOneBit} and
0040 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
0041 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
0042 * Delight</i>, (Addison Wesley, 2002).
0043 *
0044 * @author Lee Boynton
0045 * @author Arthur van Hoff
0046 * @author Josh Bloch
0047 * @author Joseph D. Darcy
0048 * @version 1.102, 07/12/07
0049 * @since JDK1.0
0050 */
0051 public final class Integer extends Number implements
0052 Comparable<Integer> {
0053 /**
0054 * A constant holding the minimum value an {@code int} can
0055 * have, -2<sup>31</sup>.
0056 */
0057 public static final int MIN_VALUE = 0x80000000;
0058
0059 /**
0060 * A constant holding the maximum value an {@code int} can
0061 * have, 2<sup>31</sup>-1.
0062 */
0063 public static final int MAX_VALUE = 0x7fffffff;
0064
0065 /**
0066 * The {@code Class} instance representing the primitive type
0067 * {@code int}.
0068 *
0069 * @since JDK1.1
0070 */
0071 public static final Class<Integer> TYPE = (Class<Integer>) Class
0072 .getPrimitiveClass("int");
0073
0074 /**
0075 * All possible chars for representing a number as a String
0076 */
0077 final static char[] digits = { '0', '1', '2', '3', '4', '5', '6',
0078 '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
0079 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
0080 'v', 'w', 'x', 'y', 'z' };
0081
0082 /**
0083 * Returns a string representation of the first argument in the
0084 * radix specified by the second argument.
0085 *
0086 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
0087 * or larger than {@code Character.MAX_RADIX}, then the radix
0088 * {@code 10} is used instead.
0089 *
0090 * <p>If the first argument is negative, the first element of the
0091 * result is the ASCII minus character {@code '-'}
0092 * (<code>'\u002D'</code>). If the first argument is not
0093 * negative, no sign character appears in the result.
0094 *
0095 * <p>The remaining characters of the result represent the magnitude
0096 * of the first argument. If the magnitude is zero, it is
0097 * represented by a single zero character {@code '0'}
0098 * (<code>'\u0030'</code>); otherwise, the first character of
0099 * the representation of the magnitude will not be the zero
0100 * character. The following ASCII characters are used as digits:
0101 *
0102 * <blockquote>
0103 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
0104 * </blockquote>
0105 *
0106 * These are <code>'\u0030'</code> through
0107 * <code>'\u0039'</code> and <code>'\u0061'</code> through
0108 * <code>'\u007A'</code>. If {@code radix} is
0109 * <var>N</var>, then the first <var>N</var> of these characters
0110 * are used as radix-<var>N</var> digits in the order shown. Thus,
0111 * the digits for hexadecimal (radix 16) are
0112 * {@code 0123456789abcdef}. If uppercase letters are
0113 * desired, the {@link java.lang.String#toUpperCase()} method may
0114 * be called on the result:
0115 *
0116 * <blockquote>
0117 * {@code Integer.toString(n, 16).toUpperCase()}
0118 * </blockquote>
0119 *
0120 * @param i an integer to be converted to a string.
0121 * @param radix the radix to use in the string representation.
0122 * @return a string representation of the argument in the specified radix.
0123 * @see java.lang.Character#MAX_RADIX
0124 * @see java.lang.Character#MIN_RADIX
0125 */
0126 public static String toString(int i, int radix) {
0127
0128 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
0129 radix = 10;
0130
0131 /* Use the faster version */
0132 if (radix == 10) {
0133 return toString(i);
0134 }
0135
0136 char buf[] = new char[33];
0137 boolean negative = (i < 0);
0138 int charPos = 32;
0139
0140 if (!negative) {
0141 i = -i;
0142 }
0143
0144 while (i <= -radix) {
0145 buf[charPos--] = digits[-(i % radix)];
0146 i = i / radix;
0147 }
0148 buf[charPos] = digits[-i];
0149
0150 if (negative) {
0151 buf[--charPos] = '-';
0152 }
0153
0154 return new String(buf, charPos, (33 - charPos));
0155 }
0156
0157 /**
0158 * Returns a string representation of the integer argument as an
0159 * unsigned integer in base 16.
0160 *
0161 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
0162 * if the argument is negative; otherwise, it is equal to the
0163 * argument. This value is converted to a string of ASCII digits
0164 * in hexadecimal (base 16) with no extra leading
0165 * {@code 0}s. If the unsigned magnitude is zero, it is
0166 * represented by a single zero character {@code '0'}
0167 * (<code>'\u0030'</code>); otherwise, the first character of
0168 * the representation of the unsigned magnitude will not be the
0169 * zero character. The following characters are used as
0170 * hexadecimal digits:
0171 *
0172 * <blockquote>
0173 * {@code 0123456789abcdef}
0174 * </blockquote>
0175 *
0176 * These are the characters <code>'\u0030'</code> through
0177 * <code>'\u0039'</code> and <code>'\u0061'</code> through
0178 * <code>'\u0066'</code>. If uppercase letters are
0179 * desired, the {@link java.lang.String#toUpperCase()} method may
0180 * be called on the result:
0181 *
0182 * <blockquote>
0183 * {@code Integer.toHexString(n).toUpperCase()}
0184 * </blockquote>
0185 *
0186 * @param i an integer to be converted to a string.
0187 * @return the string representation of the unsigned integer value
0188 * represented by the argument in hexadecimal (base 16).
0189 * @since JDK1.0.2
0190 */
0191 public static String toHexString(int i) {
0192 return toUnsignedString(i, 4);
0193 }
0194
0195 /**
0196 * Returns a string representation of the integer argument as an
0197 * unsigned integer in base 8.
0198 *
0199 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
0200 * if the argument is negative; otherwise, it is equal to the
0201 * argument. This value is converted to a string of ASCII digits
0202 * in octal (base 8) with no extra leading {@code 0}s.
0203 *
0204 * <p>If the unsigned magnitude is zero, it is represented by a
0205 * single zero character {@code '0'}
0206 * (<code>'\u0030'</code>); otherwise, the first character of
0207 * the representation of the unsigned magnitude will not be the
0208 * zero character. The following characters are used as octal
0209 * digits:
0210 *
0211 * <blockquote>
0212 * {@code 01234567}
0213 * </blockquote>
0214 *
0215 * These are the characters <code>'\u0030'</code> through
0216 * <code>'\u0037'</code>.
0217 *
0218 * @param i an integer to be converted to a string.
0219 * @return the string representation of the unsigned integer value
0220 * represented by the argument in octal (base 8).
0221 * @since JDK1.0.2
0222 */
0223 public static String toOctalString(int i) {
0224 return toUnsignedString(i, 3);
0225 }
0226
0227 /**
0228 * Returns a string representation of the integer argument as an
0229 * unsigned integer in base 2.
0230 *
0231 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
0232 * if the argument is negative; otherwise it is equal to the
0233 * argument. This value is converted to a string of ASCII digits
0234 * in binary (base 2) with no extra leading {@code 0}s.
0235 * If the unsigned magnitude is zero, it is represented by a
0236 * single zero character {@code '0'}
0237 * (<code>'\u0030'</code>); otherwise, the first character of
0238 * the representation of the unsigned magnitude will not be the
0239 * zero character. The characters {@code '0'}
0240 * (<code>'\u0030'</code>) and {@code '1'}
0241 * (<code>'\u0031'</code>) are used as binary digits.
0242 *
0243 * @param i an integer to be converted to a string.
0244 * @return the string representation of the unsigned integer value
0245 * represented by the argument in binary (base 2).
0246 * @since JDK1.0.2
0247 */
0248 public static String toBinaryString(int i) {
0249 return toUnsignedString(i, 1);
0250 }
0251
0252 /**
0253 * Convert the integer to an unsigned number.
0254 */
0255 private static String toUnsignedString(int i, int shift) {
0256 char[] buf = new char[32];
0257 int charPos = 32;
0258 int radix = 1 << shift;
0259 int mask = radix - 1;
0260 do {
0261 buf[--charPos] = digits[i & mask];
0262 i >>>= shift;
0263 } while (i != 0);
0264
0265 return new String(buf, charPos, (32 - charPos));
0266 }
0267
0268 final static char[] DigitTens = { '0', '0', '0', '0', '0', '0',
0269 '0', '0', '0', '0', '1', '1', '1', '1', '1', '1', '1', '1',
0270 '1', '1', '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
0271 '3', '3', '3', '3', '3', '3', '3', '3', '3', '3', '4', '4',
0272 '4', '4', '4', '4', '4', '4', '4', '4', '5', '5', '5', '5',
0273 '5', '5', '5', '5', '5', '5', '6', '6', '6', '6', '6', '6',
0274 '6', '6', '6', '6', '7', '7', '7', '7', '7', '7', '7', '7',
0275 '7', '7', '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
0276 '9', '9', '9', '9', '9', '9', '9', '9', '9', '9', };
0277
0278 final static char[] DigitOnes = { '0', '1', '2', '3', '4', '5',
0279 '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7',
0280 '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
0281 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1',
0282 '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3',
0283 '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5',
0284 '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7',
0285 '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
0286 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', };
0287
0288 // I use the "invariant division by multiplication" trick to
0289 // accelerate Integer.toString. In particular we want to
0290 // avoid division by 10.
0291 //
0292 // The "trick" has roughly the same performance characteristics
0293 // as the "classic" Integer.toString code on a non-JIT VM.
0294 // The trick avoids .rem and .div calls but has a longer code
0295 // path and is thus dominated by dispatch overhead. In the
0296 // JIT case the dispatch overhead doesn't exist and the
0297 // "trick" is considerably faster than the classic code.
0298 //
0299 // TODO-FIXME: convert (x * 52429) into the equiv shift-add
0300 // sequence.
0301 //
0302 // RE: Division by Invariant Integers using Multiplication
0303 // T Gralund, P Montgomery
0304 // ACM PLDI 1994
0305 //
0306
0307 /**
0308 * Returns a {@code String} object representing the
0309 * specified integer. The argument is converted to signed decimal
0310 * representation and returned as a string, exactly as if the
0311 * argument and radix 10 were given as arguments to the {@link
0312 * #toString(int, int)} method.
0313 *
0314 * @param i an integer to be converted.
0315 * @return a string representation of the argument in base 10.
0316 */
0317 public static String toString(int i) {
0318 if (i == Integer.MIN_VALUE)
0319 return "-2147483648";
0320 int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
0321 char[] buf = new char[size];
0322 getChars(i, size, buf);
0323 return new String(0, size, buf);
0324 }
0325
0326 /**
0327 * Places characters representing the integer i into the
0328 * character array buf. The characters are placed into
0329 * the buffer backwards starting with the least significant
0330 * digit at the specified index (exclusive), and working
0331 * backwards from there.
0332 *
0333 * Will fail if i == Integer.MIN_VALUE
0334 */
0335 static void getChars(int i, int index, char[] buf) {
0336 int q, r;
0337 int charPos = index;
0338 char sign = 0;
0339
0340 if (i < 0) {
0341 sign = '-';
0342 i = -i;
0343 }
0344
0345 // Generate two digits per iteration
0346 while (i >= 65536) {
0347 q = i / 100;
0348 // really: r = i - (q * 100);
0349 r = i - ((q << 6) + (q << 5) + (q << 2));
0350 i = q;
0351 buf[--charPos] = DigitOnes[r];
0352 buf[--charPos] = DigitTens[r];
0353 }
0354
0355 // Fall thru to fast mode for smaller numbers
0356 // assert(i <= 65536, i);
0357 for (;;) {
0358 q = (i * 52429) >>> (16 + 3);
0359 r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
0360 buf[--charPos] = digits[r];
0361 i = q;
0362 if (i == 0)
0363 break;
0364 }
0365 if (sign != 0) {
0366 buf[--charPos] = sign;
0367 }
0368 }
0369
0370 final static int[] sizeTable = { 9, 99, 999, 9999, 99999, 999999,
0371 9999999, 99999999, 999999999, Integer.MAX_VALUE };
0372
0373 // Requires positive x
0374 static int stringSize(int x) {
0375 for (int i = 0;; i++)
0376 if (x <= sizeTable[i])
0377 return i + 1;
0378 }
0379
0380 /**
0381 * Parses the string argument as a signed integer in the radix
0382 * specified by the second argument. The characters in the string
0383 * must all be digits of the specified radix (as determined by
0384 * whether {@link java.lang.Character#digit(char, int)} returns a
0385 * nonnegative value), except that the first character may be an
0386 * ASCII minus sign {@code '-'} (<code>'\u002D'</code>) to
0387 * indicate a negative value or an ASCII plus sign {@code '+'}
0388 * (<code>'\u002B'</code>) to indicate a positive value. The
0389 * resulting integer value is returned.
0390 *
0391 * <p>An exception of type {@code NumberFormatException} is
0392 * thrown if any of the following situations occurs:
0393 * <ul>
0394 * <li>The first argument is {@code null} or is a string of
0395 * length zero.
0396 *
0397 * <li>The radix is either smaller than
0398 * {@link java.lang.Character#MIN_RADIX} or
0399 * larger than {@link java.lang.Character#MAX_RADIX}.
0400 *
0401 * <li>Any character of the string is not a digit of the specified
0402 * radix, except that the first character may be a minus sign
0403 * {@code '-'} (<code>'\u002D'</code>) or plus sign
0404 * {@code '+'} (<code>'\u002B'</code>) provided that the
0405 * string is longer than length 1.
0406 *
0407 * <li>The value represented by the string is not a value of type
0408 * {@code int}.
0409 * </ul>
0410 *
0411 * <p>Examples:
0412 * <blockquote><pre>
0413 * parseInt("0", 10) returns 0
0414 * parseInt("473", 10) returns 473
0415 * parseInt("+42", 10) returns 42
0416 * parseInt("-0", 10) returns 0
0417 * parseInt("-FF", 16) returns -255
0418 * parseInt("1100110", 2) returns 102
0419 * parseInt("2147483647", 10) returns 2147483647
0420 * parseInt("-2147483648", 10) returns -2147483648
0421 * parseInt("2147483648", 10) throws a NumberFormatException
0422 * parseInt("99", 8) throws a NumberFormatException
0423 * parseInt("Kona", 10) throws a NumberFormatException
0424 * parseInt("Kona", 27) returns 411787
0425 * </pre></blockquote>
0426 *
0427 * @param s the {@code String} containing the integer
0428 * representation to be parsed
0429 * @param radix the radix to be used while parsing {@code s}.
0430 * @return the integer represented by the string argument in the
0431 * specified radix.
0432 * @exception NumberFormatException if the {@code String}
0433 * does not contain a parsable {@code int}.
0434 */
0435 public static int parseInt(String s, int radix)
0436 throws NumberFormatException {
0437 if (s == null) {
0438 throw new NumberFormatException("null");
0439 }
0440
0441 if (radix < Character.MIN_RADIX) {
0442 throw new NumberFormatException("radix " + radix
0443 + " less than Character.MIN_RADIX");
0444 }
0445
0446 if (radix > Character.MAX_RADIX) {
0447 throw new NumberFormatException("radix " + radix
0448 + " greater than Character.MAX_RADIX");
0449 }
0450
0451 int result = 0;
0452 boolean negative = false;
0453 int i = 0, len = s.length();
0454 int limit = -Integer.MAX_VALUE;
0455 int multmin;
0456 int digit;
0457
0458 if (len > 0) {
0459 char firstChar = s.charAt(0);
0460 if (firstChar < '0') { // Possible leading "+" or "-"
0461 if (firstChar == '-') {
0462 negative = true;
0463 limit = Integer.MIN_VALUE;
0464 } else if (firstChar != '+')
0465 throw NumberFormatException.forInputString(s);
0466
0467 if (len == 1) // Cannot have lone "+" or "-"
0468 throw NumberFormatException.forInputString(s);
0469 i++;
0470 }
0471 multmin = limit / radix;
0472 while (i < len) {
0473 // Accumulating negatively avoids surprises near MAX_VALUE
0474 digit = Character.digit(s.charAt(i++), radix);
0475 if (digit < 0) {
0476 throw NumberFormatException.forInputString(s);
0477 }
0478 if (result < multmin) {
0479 throw NumberFormatException.forInputString(s);
0480 }
0481 result *= radix;
0482 if (result < limit + digit) {
0483 throw NumberFormatException.forInputString(s);
0484 }
0485 result -= digit;
0486 }
0487 } else {
0488 throw NumberFormatException.forInputString(s);
0489 }
0490 return negative ? result : -result;
0491 }
0492
0493 /**
0494 * Parses the string argument as a signed decimal integer. The
0495 * characters in the string must all be decimal digits, except
0496 * that the first character may be an ASCII minus sign {@code '-'}
0497 * (<code>'\u002D'</code>) to indicate a negative value or an
0498 * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to
0499 * indicate a positive value. The resulting integer value is
0500 * returned, exactly as if the argument and the radix 10 were
0501 * given as arguments to the {@link #parseInt(java.lang.String,
0502 * int)} method.
0503 *
0504 * @param s a {@code String} containing the {@code int}
0505 * representation to be parsed
0506 * @return the integer value represented by the argument in decimal.
0507 * @exception NumberFormatException if the string does not contain a
0508 * parsable integer.
0509 */
0510 public static int parseInt(String s) throws NumberFormatException {
0511 return parseInt(s, 10);
0512 }
0513
0514 /**
0515 * Returns an {@code Integer} object holding the value
0516 * extracted from the specified {@code String} when parsed
0517 * with the radix given by the second argument. The first argument
0518 * is interpreted as representing a signed integer in the radix
0519 * specified by the second argument, exactly as if the arguments
0520 * were given to the {@link #parseInt(java.lang.String, int)}
0521 * method. The result is an {@code Integer} object that
0522 * represents the integer value specified by the string.
0523 *
0524 * <p>In other words, this method returns an {@code Integer}
0525 * object equal to the value of:
0526 *
0527 * <blockquote>
0528 * {@code new Integer(Integer.parseInt(s, radix))}
0529 * </blockquote>
0530 *
0531 * @param s the string to be parsed.
0532 * @param radix the radix to be used in interpreting {@code s}
0533 * @return an {@code Integer} object holding the value
0534 * represented by the string argument in the specified
0535 * radix.
0536 * @exception NumberFormatException if the {@code String}
0537 * does not contain a parsable {@code int}.
0538 */
0539 public static Integer valueOf(String s, int radix)
0540 throws NumberFormatException {
0541 return new Integer(parseInt(s, radix));
0542 }
0543
0544 /**
0545 * Returns an {@code Integer} object holding the
0546 * value of the specified {@code String}. The argument is
0547 * interpreted as representing a signed decimal integer, exactly
0548 * as if the argument were given to the {@link
0549 * #parseInt(java.lang.String)} method. The result is an
0550 * {@code Integer} object that represents the integer value
0551 * specified by the string.
0552 *
0553 * <p>In other words, this method returns an {@code Integer}
0554 * object equal to the value of:
0555 *
0556 * <blockquote>
0557 * {@code new Integer(Integer.parseInt(s))}
0558 * </blockquote>
0559 *
0560 * @param s the string to be parsed.
0561 * @return an {@code Integer} object holding the value
0562 * represented by the string argument.
0563 * @exception NumberFormatException if the string cannot be parsed
0564 * as an integer.
0565 */
0566 public static Integer valueOf(String s)
0567 throws NumberFormatException {
0568 return new Integer(parseInt(s, 10));
0569 }
0570
0571 private static class IntegerCache {
0572 private IntegerCache() {
0573 }
0574
0575 static final Integer cache[] = new Integer[-(-128) + 127 + 1];
0576
0577 static {
0578 for (int i = 0; i < cache.length; i++)
0579 cache[i] = new Integer(i - 128);
0580 }
0581 }
0582
0583 /**
0584 * Returns an {@code Integer} instance representing the specified
0585 * {@code int} value. If a new {@code Integer} instance is not
0586 * required, this method should generally be used in preference to
0587 * the constructor {@link #Integer(int)}, as this method is likely
0588 * to yield significantly better space and time performance by
0589 * caching frequently requested values.
0590 *
0591 * @param i an {@code int} value.
0592 * @return an {@code Integer} instance representing {@code i}.
0593 * @since 1.5
0594 */
0595 public static Integer valueOf(int i) {
0596 final int offset = 128;
0597 if (i >= -128 && i <= 127) { // must cache
0598 return IntegerCache.cache[i + offset];
0599 }
0600 return new Integer(i);
0601 }
0602
0603 /**
0604 * The value of the {@code Integer}.
0605 *
0606 * @serial
0607 */
0608 private final int value;
0609
0610 /**
0611 * Constructs a newly allocated {@code Integer} object that
0612 * represents the specified {@code int} value.
0613 *
0614 * @param value the value to be represented by the
0615 * {@code Integer} object.
0616 */
0617 public Integer(int value) {
0618 this .value = value;
0619 }
0620
0621 /**
0622 * Constructs a newly allocated {@code Integer} object that
0623 * represents the {@code int} value indicated by the
0624 * {@code String} parameter. The string is converted to an
0625 * {@code int} value in exactly the manner used by the
0626 * {@code parseInt} method for radix 10.
0627 *
0628 * @param s the {@code String} to be converted to an
0629 * {@code Integer}.
0630 * @exception NumberFormatException if the {@code String} does not
0631 * contain a parsable integer.
0632 * @see java.lang.Integer#parseInt(java.lang.String, int)
0633 */
0634 public Integer(String s) throws NumberFormatException {
0635 this .value = parseInt(s, 10);
0636 }
0637
0638 /**
0639 * Returns the value of this {@code Integer} as a
0640 * {@code byte}.
0641 */
0642 public byte byteValue() {
0643 return (byte) value;
0644 }
0645
0646 /**
0647 * Returns the value of this {@code Integer} as a
0648 * {@code short}.
0649 */
0650 public short shortValue() {
0651 return (short) value;
0652 }
0653
0654 /**
0655 * Returns the value of this {@code Integer} as an
0656 * {@code int}.
0657 */
0658 public int intValue() {
0659 return value;
0660 }
0661
0662 /**
0663 * Returns the value of this {@code Integer} as a
0664 * {@code long}.
0665 */
0666 public long longValue() {
0667 return (long) value;
0668 }
0669
0670 /**
0671 * Returns the value of this {@code Integer} as a
0672 * {@code float}.
0673 */
0674 public float floatValue() {
0675 return (float) value;
0676 }
0677
0678 /**
0679 * Returns the value of this {@code Integer} as a
0680 * {@code double}.
0681 */
0682 public double doubleValue() {
0683 return (double) value;
0684 }
0685
0686 /**
0687 * Returns a {@code String} object representing this
0688 * {@code Integer}'s value. The value is converted to signed
0689 * decimal representation and returned as a string, exactly as if
0690 * the integer value were given as an argument to the {@link
0691 * java.lang.Integer#toString(int)} method.
0692 *
0693 * @return a string representation of the value of this object in
0694 * base 10.
0695 */
0696 public String toString() {
0697 return String.valueOf(value);
0698 }
0699
0700 /**
0701 * Returns a hash code for this {@code Integer}.
0702 *
0703 * @return a hash code value for this object, equal to the
0704 * primitive {@code int} value represented by this
0705 * {@code Integer} object.
0706 */
0707 public int hashCode() {
0708 return value;
0709 }
0710
0711 /**
0712 * Compares this object to the specified object. The result is
0713 * {@code true} if and only if the argument is not
0714 * {@code null} and is an {@code Integer} object that
0715 * contains the same {@code int} value as this object.
0716 *
0717 * @param obj the object to compare with.
0718 * @return {@code true} if the objects are the same;
0719 * {@code false} otherwise.
0720 */
0721 public boolean equals(Object obj) {
0722 if (obj instanceof Integer) {
0723 return value == ((Integer) obj).intValue();
0724 }
0725 return false;
0726 }
0727
0728 /**
0729 * Determines the integer value of the system property with the
0730 * specified name.
0731 *
0732 * <p>The first argument is treated as the name of a system property.
0733 * System properties are accessible through the
0734 * {@link java.lang.System#getProperty(java.lang.String)} method. The
0735 * string value of this property is then interpreted as an integer
0736 * value and an {@code Integer} object representing this value is
0737 * returned. Details of possible numeric formats can be found with
0738 * the definition of {@code getProperty}.
0739 *
0740 * <p>If there is no property with the specified name, if the specified name
0741 * is empty or {@code null}, or if the property does not have
0742 * the correct numeric format, then {@code null} is returned.
0743 *
0744 * <p>In other words, this method returns an {@code Integer}
0745 * object equal to the value of:
0746 *
0747 * <blockquote>
0748 * {@code getInteger(nm, null)}
0749 * </blockquote>
0750 *
0751 * @param nm property name.
0752 * @return the {@code Integer} value of the property.
0753 * @see java.lang.System#getProperty(java.lang.String)
0754 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
0755 */
0756 public static Integer getInteger(String nm) {
0757 return getInteger(nm, null);
0758 }
0759
0760 /**
0761 * Determines the integer value of the system property with the
0762 * specified name.
0763 *
0764 * <p>The first argument is treated as the name of a system property.
0765 * System properties are accessible through the {@link
0766 * java.lang.System#getProperty(java.lang.String)} method. The
0767 * string value of this property is then interpreted as an integer
0768 * value and an {@code Integer} object representing this value is
0769 * returned. Details of possible numeric formats can be found with
0770 * the definition of {@code getProperty}.
0771 *
0772 * <p>The second argument is the default value. An {@code Integer} object
0773 * that represents the value of the second argument is returned if there
0774 * is no property of the specified name, if the property does not have
0775 * the correct numeric format, or if the specified name is empty or
0776 * {@code null}.
0777 *
0778 * <p>In other words, this method returns an {@code Integer} object
0779 * equal to the value of:
0780 *
0781 * <blockquote>
0782 * {@code getInteger(nm, new Integer(val))}
0783 * </blockquote>
0784 *
0785 * but in practice it may be implemented in a manner such as:
0786 *
0787 * <blockquote><pre>
0788 * Integer result = getInteger(nm, null);
0789 * return (result == null) ? new Integer(val) : result;
0790 * </pre></blockquote>
0791 *
0792 * to avoid the unnecessary allocation of an {@code Integer}
0793 * object when the default value is not needed.
0794 *
0795 * @param nm property name.
0796 * @param val default value.
0797 * @return the {@code Integer} value of the property.
0798 * @see java.lang.System#getProperty(java.lang.String)
0799 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
0800 */
0801 public static Integer getInteger(String nm, int val) {
0802 Integer result = getInteger(nm, null);
0803 return (result == null) ? new Integer(val) : result;
0804 }
0805
0806 /**
0807 * Returns the integer value of the system property with the
0808 * specified name. The first argument is treated as the name of a
0809 * system property. System properties are accessible through the
0810 * {@link java.lang.System#getProperty(java.lang.String)} method.
0811 * The string value of this property is then interpreted as an
0812 * integer value, as per the {@code Integer.decode} method,
0813 * and an {@code Integer} object representing this value is
0814 * returned.
0815 *
0816 * <ul><li>If the property value begins with the two ASCII characters
0817 * {@code 0x} or the ASCII character {@code #}, not
0818 * followed by a minus sign, then the rest of it is parsed as a
0819 * hexadecimal integer exactly as by the method
0820 * {@link #valueOf(java.lang.String, int)} with radix 16.
0821 * <li>If the property value begins with the ASCII character
0822 * {@code 0} followed by another character, it is parsed as an
0823 * octal integer exactly as by the method
0824 * {@link #valueOf(java.lang.String, int)} with radix 8.
0825 * <li>Otherwise, the property value is parsed as a decimal integer
0826 * exactly as by the method {@link #valueOf(java.lang.String, int)}
0827 * with radix 10.
0828 * </ul>
0829 *
0830 * <p>The second argument is the default value. The default value is
0831 * returned if there is no property of the specified name, if the
0832 * property does not have the correct numeric format, or if the
0833 * specified name is empty or {@code null}.
0834 *
0835 * @param nm property name.
0836 * @param val default value.
0837 * @return the {@code Integer} value of the property.
0838 * @see java.lang.System#getProperty(java.lang.String)
0839 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
0840 * @see java.lang.Integer#decode
0841 */
0842 public static Integer getInteger(String nm, Integer val) {
0843 String v = null;
0844 try {
0845 v = System.getProperty(nm);
0846 } catch (IllegalArgumentException e) {
0847 } catch (NullPointerException e) {
0848 }
0849 if (v != null) {
0850 try {
0851 return Integer.decode(v);
0852 } catch (NumberFormatException e) {
0853 }
0854 }
0855 return val;
0856 }
0857
0858 /**
0859 * Decodes a {@code String} into an {@code Integer}.
0860 * Accepts decimal, hexadecimal, and octal numbers given
0861 * by the following grammar:
0862 *
0863 * <blockquote>
0864 * <dl>
0865 * <dt><i>DecodableString:</i>
0866 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
0867 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
0868 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
0869 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
0870 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
0871 * <p>
0872 * <dt><i>Sign:</i>
0873 * <dd>{@code -}
0874 * <dd>{@code +}
0875 * </dl>
0876 * </blockquote>
0877 *
0878 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
0879 * are defined in <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">§3.10.1</a>
0880 * of the <a href="http://java.sun.com/docs/books/jls/html/">Java
0881 * Language Specification</a>.
0882 *
0883 * <p>The sequence of characters following an optional
0884 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
0885 * "{@code #}", or leading zero) is parsed as by the {@code
0886 * Integer.parseInt} method with the indicated radix (10, 16, or
0887 * 8). This sequence of characters must represent a positive
0888 * value or a {@link NumberFormatException} will be thrown. The
0889 * result is negated if first character of the specified {@code
0890 * String} is the minus sign. No whitespace characters are
0891 * permitted in the {@code String}.
0892 *
0893 * @param nm the {@code String} to decode.
0894 * @return an {@code Integer} object holding the {@code int}
0895 * value represented by {@code nm}
0896 * @exception NumberFormatException if the {@code String} does not
0897 * contain a parsable integer.
0898 * @see java.lang.Integer#parseInt(java.lang.String, int)
0899 */
0900 public static Integer decode(String nm)
0901 throws NumberFormatException {
0902 int radix = 10;
0903 int index = 0;
0904 boolean negative = false;
0905 Integer result;
0906
0907 if (nm.length() == 0)
0908 throw new NumberFormatException("Zero length string");
0909 char firstChar = nm.charAt(0);
0910 // Handle sign, if present
0911 if (firstChar == '-') {
0912 negative = true;
0913 index++;
0914 } else if (firstChar == '+')
0915 index++;
0916
0917 // Handle radix specifier, if present
0918 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
0919 index += 2;
0920 radix = 16;
0921 } else if (nm.startsWith("#", index)) {
0922 index++;
0923 radix = 16;
0924 } else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
0925 index++;
0926 radix = 8;
0927 }
0928
0929 if (nm.startsWith("-", index) || nm.startsWith("+", index))
0930 throw new NumberFormatException(
0931 "Sign character in wrong position");
0932
0933 try {
0934 result = Integer.valueOf(nm.substring(index), radix);
0935 result = negative ? new Integer(-result.intValue())
0936 : result;
0937 } catch (NumberFormatException e) {
0938 // If number is Integer.MIN_VALUE, we'll end up here. The next line
0939 // handles this case, and causes any genuine format error to be
0940 // rethrown.
0941 String constant = negative ? ("-" + nm.substring(index))
0942 : nm.substring(index);
0943 result = Integer.valueOf(constant, radix);
0944 }
0945 return result;
0946 }
0947
0948 /**
0949 * Compares two {@code Integer} objects numerically.
0950 *
0951 * @param anotherInteger the {@code Integer} to be compared.
0952 * @return the value {@code 0} if this {@code Integer} is
0953 * equal to the argument {@code Integer}; a value less than
0954 * {@code 0} if this {@code Integer} is numerically less
0955 * than the argument {@code Integer}; and a value greater
0956 * than {@code 0} if this {@code Integer} is numerically
0957 * greater than the argument {@code Integer} (signed
0958 * comparison).
0959 * @since 1.2
0960 */
0961 public int compareTo(Integer anotherInteger) {
0962 int this Val = this .value;
0963 int anotherVal = anotherInteger.value;
0964 return (this Val < anotherVal ? -1 : (this Val == anotherVal ? 0
0965 : 1));
0966 }
0967
0968 // Bit twiddling
0969
0970 /**
0971 * The number of bits used to represent an {@code int} value in two's
0972 * complement binary form.
0973 *
0974 * @since 1.5
0975 */
0976 public static final int SIZE = 32;
0977
0978 /**
0979 * Returns an {@code int} value with at most a single one-bit, in the
0980 * position of the highest-order ("leftmost") one-bit in the specified
0981 * {@code int} value. Returns zero if the specified value has no
0982 * one-bits in its two's complement binary representation, that is, if it
0983 * is equal to zero.
0984 *
0985 * @return an {@code int} value with a single one-bit, in the position
0986 * of the highest-order one-bit in the specified value, or zero if
0987 * the specified value is itself equal to zero.
0988 * @since 1.5
0989 */
0990 public static int highestOneBit(int i) {
0991 // HD, Figure 3-1
0992 i |= (i >> 1);
0993 i |= (i >> 2);
0994 i |= (i >> 4);
0995 i |= (i >> 8);
0996 i |= (i >> 16);
0997 return i - (i >>> 1);
0998 }
0999
1000 /**
1001 * Returns an {@code int} value with at most a single one-bit, in the
1002 * position of the lowest-order ("rightmost") one-bit in the specified
1003 * {@code int} value. Returns zero if the specified value has no
1004 * one-bits in its two's complement binary representation, that is, if it
1005 * is equal to zero.
1006 *
1007 * @return an {@code int} value with a single one-bit, in the position
1008 * of the lowest-order one-bit in the specified value, or zero if
1009 * the specified value is itself equal to zero.
1010 * @since 1.5
1011 */
1012 public static int lowestOneBit(int i) {
1013 // HD, Section 2-1
1014 return i & -i;
1015 }
1016
1017 /**
1018 * Returns the number of zero bits preceding the highest-order
1019 * ("leftmost") one-bit in the two's complement binary representation
1020 * of the specified {@code int} value. Returns 32 if the
1021 * specified value has no one-bits in its two's complement representation,
1022 * in other words if it is equal to zero.
1023 *
1024 * <p>Note that this method is closely related to the logarithm base 2.
1025 * For all positive {@code int} values x:
1026 * <ul>
1027 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
1028 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
1029 * </ul>
1030 *
1031 * @return the number of zero bits preceding the highest-order
1032 * ("leftmost") one-bit in the two's complement binary representation
1033 * of the specified {@code int} value, or 32 if the value
1034 * is equal to zero.
1035 * @since 1.5
1036 */
1037 public static int numberOfLeadingZeros(int i) {
1038 // HD, Figure 5-6
1039 if (i == 0)
1040 return 32;
1041 int n = 1;
1042 if (i >>> 16 == 0) {
1043 n += 16;
1044 i <<= 16;
1045 }
1046 if (i >>> 24 == 0) {
1047 n += 8;
1048 i <<= 8;
1049 }
1050 if (i >>> 28 == 0) {
1051 n += 4;
1052 i <<= 4;
1053 }
1054 if (i >>> 30 == 0) {
1055 n += 2;
1056 i <<= 2;
1057 }
1058 n -= i >>> 31;
1059 return n;
1060 }
1061
1062 /**
1063 * Returns the number of zero bits following the lowest-order ("rightmost")
1064 * one-bit in the two's complement binary representation of the specified
1065 * {@code int} value. Returns 32 if the specified value has no
1066 * one-bits in its two's complement representation, in other words if it is
1067 * equal to zero.
1068 *
1069 * @return the number of zero bits following the lowest-order ("rightmost")
1070 * one-bit in the two's complement binary representation of the
1071 * specified {@code int} value, or 32 if the value is equal
1072 * to zero.
1073 * @since 1.5
1074 */
1075 public static int numberOfTrailingZeros(int i) {
1076 // HD, Figure 5-14
1077 int y;
1078 if (i == 0)
1079 return 32;
1080 int n = 31;
1081 y = i << 16;
1082 if (y != 0) {
1083 n = n - 16;
1084 i = y;
1085 }
1086 y = i << 8;
1087 if (y != 0) {
1088 n = n - 8;
1089 i = y;
1090 }
1091 y = i << 4;
1092 if (y != 0) {
1093 n = n - 4;
1094 i = y;
1095 }
1096 y = i << 2;
1097 if (y != 0) {
1098 n = n - 2;
1099 i = y;
1100 }
1101 return n - ((i << 1) >>> 31);
1102 }
1103
1104 /**
1105 * Returns the number of one-bits in the two's complement binary
1106 * representation of the specified {@code int} value. This function is
1107 * sometimes referred to as the <i>population count</i>.
1108 *
1109 * @return the number of one-bits in the two's complement binary
1110 * representation of the specified {@code int} value.
1111 * @since 1.5
1112 */
1113 public static int bitCount(int i) {
1114 // HD, Figure 5-2
1115 i = i - ((i >>> 1) & 0x55555555);
1116 i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
1117 i = (i + (i >>> 4)) & 0x0f0f0f0f;
1118 i = i + (i >>> 8);
1119 i = i + (i >>> 16);
1120 return i & 0x3f;
1121 }
1122
1123 /**
1124 * Returns the value obtained by rotating the two's complement binary
1125 * representation of the specified {@code int} value left by the
1126 * specified number of bits. (Bits shifted out of the left hand, or
1127 * high-order, side reenter on the right, or low-order.)
1128 *
1129 * <p>Note that left rotation with a negative distance is equivalent to
1130 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1131 * distance)}. Note also that rotation by any multiple of 32 is a
1132 * no-op, so all but the last five bits of the rotation distance can be
1133 * ignored, even if the distance is negative: {@code rotateLeft(val,
1134 * distance) == rotateLeft(val, distance & 0x1F)}.
1135 *
1136 * @return the value obtained by rotating the two's complement binary
1137 * representation of the specified {@code int} value left by the
1138 * specified number of bits.
1139 * @since 1.5
1140 */
1141 public static int rotateLeft(int i, int distance) {
1142 return (i << distance) | (i >>> -distance);
1143 }
1144
1145 /**
1146 * Returns the value obtained by rotating the two's complement binary
1147 * representation of the specified {@code int} value right by the
1148 * specified number of bits. (Bits shifted out of the right hand, or
1149 * low-order, side reenter on the left, or high-order.)
1150 *
1151 * <p>Note that right rotation with a negative distance is equivalent to
1152 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1153 * distance)}. Note also that rotation by any multiple of 32 is a
1154 * no-op, so all but the last five bits of the rotation distance can be
1155 * ignored, even if the distance is negative: {@code rotateRight(val,
1156 * distance) == rotateRight(val, distance & 0x1F)}.
1157 *
1158 * @return the value obtained by rotating the two's complement binary
1159 * representation of the specified {@code int} value right by the
1160 * specified number of bits.
1161 * @since 1.5
1162 */
1163 public static int rotateRight(int i, int distance) {
1164 return (i >>> distance) | (i << -distance);
1165 }
1166
1167 /**
1168 * Returns the value obtained by reversing the order of the bits in the
1169 * two's complement binary representation of the specified {@code int}
1170 * value.
1171 *
1172 * @return the value obtained by reversing order of the bits in the
1173 * specified {@code int} value.
1174 * @since 1.5
1175 */
1176 public static int reverse(int i) {
1177 // HD, Figure 7-1
1178 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
1179 i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
1180 i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
1181 i = (i << 24) | ((i & 0xff00) << 8) | ((i >>> 8) & 0xff00)
1182 | (i >>> 24);
1183 return i;
1184 }
1185
1186 /**
1187 * Returns the signum function of the specified {@code int} value. (The
1188 * return value is -1 if the specified value is negative; 0 if the
1189 * specified value is zero; and 1 if the specified value is positive.)
1190 *
1191 * @return the signum function of the specified {@code int} value.
1192 * @since 1.5
1193 */
1194 public static int signum(int i) {
1195 // HD, Section 2-7
1196 return (i >> 31) | (-i >>> 31);
1197 }
1198
1199 /**
1200 * Returns the value obtained by reversing the order of the bytes in the
1201 * two's complement representation of the specified {@code int} value.
1202 *
1203 * @return the value obtained by reversing the bytes in the specified
1204 * {@code int} value.
1205 * @since 1.5
1206 */
1207 public static int reverseBytes(int i) {
1208 return ((i >>> 24)) | ((i >> 8) & 0xFF00)
1209 | ((i << 8) & 0xFF0000) | ((i << 24));
1210 }
1211
1212 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1213 private static final long serialVersionUID = 1360826667806852920L;
1214 }
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