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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