jaroslav@49: /*
jaroslav@49:  * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
jaroslav@49:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@49:  *
jaroslav@49:  * This code is free software; you can redistribute it and/or modify it
jaroslav@49:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@49:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@49:  * particular file as subject to the "Classpath" exception as provided
jaroslav@49:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@49:  *
jaroslav@49:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@49:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@49:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@49:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@49:  * accompanied this code).
jaroslav@49:  *
jaroslav@49:  * You should have received a copy of the GNU General Public License version
jaroslav@49:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@49:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@49:  *
jaroslav@49:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@49:  * or visit www.oracle.com if you need additional information or have any
jaroslav@49:  * questions.
jaroslav@49:  */
jaroslav@49: 
jaroslav@49: package java.lang;
jaroslav@49: 
jaroslav@49: import java.util.Properties;
jaroslav@49: 
jaroslav@49: /**
jaroslav@49:  * The {@code Integer} class wraps a value of the primitive type
jaroslav@49:  * {@code int} in an object. An object of type {@code Integer}
jaroslav@49:  * contains a single field whose type is {@code int}.
jaroslav@49:  *
jaroslav@49:  * <p>In addition, this class provides several methods for converting
jaroslav@49:  * an {@code int} to a {@code String} and a {@code String} to an
jaroslav@49:  * {@code int}, as well as other constants and methods useful when
jaroslav@49:  * dealing with an {@code int}.
jaroslav@49:  *
jaroslav@49:  * <p>Implementation note: The implementations of the "bit twiddling"
jaroslav@49:  * methods (such as {@link #highestOneBit(int) highestOneBit} and
jaroslav@49:  * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
jaroslav@49:  * based on material from Henry S. Warren, Jr.'s <i>Hacker's
jaroslav@49:  * Delight</i>, (Addison Wesley, 2002).
jaroslav@49:  *
jaroslav@49:  * @author  Lee Boynton
jaroslav@49:  * @author  Arthur van Hoff
jaroslav@49:  * @author  Josh Bloch
jaroslav@49:  * @author  Joseph D. Darcy
jaroslav@49:  * @since JDK1.0
jaroslav@49:  */
jaroslav@49: public final class Integer extends Number implements Comparable<Integer> {
jaroslav@49:     /**
jaroslav@49:      * A constant holding the minimum value an {@code int} can
jaroslav@49:      * have, -2<sup>31</sup>.
jaroslav@49:      */
jaroslav@49:     public static final int   MIN_VALUE = 0x80000000;
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * A constant holding the maximum value an {@code int} can
jaroslav@49:      * have, 2<sup>31</sup>-1.
jaroslav@49:      */
jaroslav@49:     public static final int   MAX_VALUE = 0x7fffffff;
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * The {@code Class} instance representing the primitive type
jaroslav@49:      * {@code int}.
jaroslav@49:      *
jaroslav@49:      * @since   JDK1.1
jaroslav@49:      */
jaroslav@49:     public static final Class<Integer>  TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * All possible chars for representing a number as a String
jaroslav@49:      */
jaroslav@49:     final static char[] digits = {
jaroslav@49:         '0' , '1' , '2' , '3' , '4' , '5' ,
jaroslav@49:         '6' , '7' , '8' , '9' , 'a' , 'b' ,
jaroslav@49:         'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
jaroslav@49:         'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
jaroslav@49:         'o' , 'p' , 'q' , 'r' , 's' , 't' ,
jaroslav@49:         'u' , 'v' , 'w' , 'x' , 'y' , 'z'
jaroslav@49:     };
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns a string representation of the first argument in the
jaroslav@49:      * radix specified by the second argument.
jaroslav@49:      *
jaroslav@49:      * <p>If the radix is smaller than {@code Character.MIN_RADIX}
jaroslav@49:      * or larger than {@code Character.MAX_RADIX}, then the radix
jaroslav@49:      * {@code 10} is used instead.
jaroslav@49:      *
jaroslav@49:      * <p>If the first argument is negative, the first element of the
jaroslav@49:      * result is the ASCII minus character {@code '-'}
jaroslav@49:      * (<code>'&#92;u002D'</code>). If the first argument is not
jaroslav@49:      * negative, no sign character appears in the result.
jaroslav@49:      *
jaroslav@49:      * <p>The remaining characters of the result represent the magnitude
jaroslav@49:      * of the first argument. If the magnitude is zero, it is
jaroslav@49:      * represented by a single zero character {@code '0'}
jaroslav@49:      * (<code>'&#92;u0030'</code>); otherwise, the first character of
jaroslav@49:      * the representation of the magnitude will not be the zero
jaroslav@49:      * character.  The following ASCII characters are used as digits:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *   {@code 0123456789abcdefghijklmnopqrstuvwxyz}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * These are <code>'&#92;u0030'</code> through
jaroslav@49:      * <code>'&#92;u0039'</code> and <code>'&#92;u0061'</code> through
jaroslav@49:      * <code>'&#92;u007A'</code>. If {@code radix} is
jaroslav@49:      * <var>N</var>, then the first <var>N</var> of these characters
jaroslav@49:      * are used as radix-<var>N</var> digits in the order shown. Thus,
jaroslav@49:      * the digits for hexadecimal (radix 16) are
jaroslav@49:      * {@code 0123456789abcdef}. If uppercase letters are
jaroslav@49:      * desired, the {@link java.lang.String#toUpperCase()} method may
jaroslav@49:      * be called on the result:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *  {@code Integer.toString(n, 16).toUpperCase()}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * @param   i       an integer to be converted to a string.
jaroslav@49:      * @param   radix   the radix to use in the string representation.
jaroslav@49:      * @return  a string representation of the argument in the specified radix.
jaroslav@49:      * @see     java.lang.Character#MAX_RADIX
jaroslav@49:      * @see     java.lang.Character#MIN_RADIX
jaroslav@49:      */
jaroslav@49:     public static String toString(int i, int radix) {
jaroslav@49: 
jaroslav@49:         if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
jaroslav@49:             radix = 10;
jaroslav@49: 
jaroslav@49:         /* Use the faster version */
jaroslav@49:         if (radix == 10) {
jaroslav@49:             return toString(i);
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         char buf[] = new char[33];
jaroslav@49:         boolean negative = (i < 0);
jaroslav@49:         int charPos = 32;
jaroslav@49: 
jaroslav@49:         if (!negative) {
jaroslav@49:             i = -i;
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         while (i <= -radix) {
jaroslav@49:             buf[charPos--] = digits[-(i % radix)];
jaroslav@49:             i = i / radix;
jaroslav@49:         }
jaroslav@49:         buf[charPos] = digits[-i];
jaroslav@49: 
jaroslav@49:         if (negative) {
jaroslav@49:             buf[--charPos] = '-';
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         return new String(buf, charPos, (33 - charPos));
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns a string representation of the integer argument as an
jaroslav@49:      * unsigned integer in base&nbsp;16.
jaroslav@49:      *
jaroslav@49:      * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
jaroslav@49:      * if the argument is negative; otherwise, it is equal to the
jaroslav@49:      * argument.  This value is converted to a string of ASCII digits
jaroslav@49:      * in hexadecimal (base&nbsp;16) with no extra leading
jaroslav@49:      * {@code 0}s. If the unsigned magnitude is zero, it is
jaroslav@49:      * represented by a single zero character {@code '0'}
jaroslav@49:      * (<code>'&#92;u0030'</code>); otherwise, the first character of
jaroslav@49:      * the representation of the unsigned magnitude will not be the
jaroslav@49:      * zero character. The following characters are used as
jaroslav@49:      * hexadecimal digits:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *  {@code 0123456789abcdef}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * These are the characters <code>'&#92;u0030'</code> through
jaroslav@49:      * <code>'&#92;u0039'</code> and <code>'&#92;u0061'</code> through
jaroslav@49:      * <code>'&#92;u0066'</code>. If uppercase letters are
jaroslav@49:      * desired, the {@link java.lang.String#toUpperCase()} method may
jaroslav@49:      * be called on the result:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *  {@code Integer.toHexString(n).toUpperCase()}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * @param   i   an integer to be converted to a string.
jaroslav@49:      * @return  the string representation of the unsigned integer value
jaroslav@49:      *          represented by the argument in hexadecimal (base&nbsp;16).
jaroslav@49:      * @since   JDK1.0.2
jaroslav@49:      */
jaroslav@49:     public static String toHexString(int i) {
jaroslav@49:         return toUnsignedString(i, 4);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns a string representation of the integer argument as an
jaroslav@49:      * unsigned integer in base&nbsp;8.
jaroslav@49:      *
jaroslav@49:      * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
jaroslav@49:      * if the argument is negative; otherwise, it is equal to the
jaroslav@49:      * argument.  This value is converted to a string of ASCII digits
jaroslav@49:      * in octal (base&nbsp;8) with no extra leading {@code 0}s.
jaroslav@49:      *
jaroslav@49:      * <p>If the unsigned magnitude is zero, it is represented by a
jaroslav@49:      * single zero character {@code '0'}
jaroslav@49:      * (<code>'&#92;u0030'</code>); otherwise, the first character of
jaroslav@49:      * the representation of the unsigned magnitude will not be the
jaroslav@49:      * zero character. The following characters are used as octal
jaroslav@49:      * digits:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      * {@code 01234567}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * These are the characters <code>'&#92;u0030'</code> through
jaroslav@49:      * <code>'&#92;u0037'</code>.
jaroslav@49:      *
jaroslav@49:      * @param   i   an integer to be converted to a string.
jaroslav@49:      * @return  the string representation of the unsigned integer value
jaroslav@49:      *          represented by the argument in octal (base&nbsp;8).
jaroslav@49:      * @since   JDK1.0.2
jaroslav@49:      */
jaroslav@49:     public static String toOctalString(int i) {
jaroslav@49:         return toUnsignedString(i, 3);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns a string representation of the integer argument as an
jaroslav@49:      * unsigned integer in base&nbsp;2.
jaroslav@49:      *
jaroslav@49:      * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
jaroslav@49:      * if the argument is negative; otherwise it is equal to the
jaroslav@49:      * argument.  This value is converted to a string of ASCII digits
jaroslav@49:      * in binary (base&nbsp;2) with no extra leading {@code 0}s.
jaroslav@49:      * If the unsigned magnitude is zero, it is represented by a
jaroslav@49:      * single zero character {@code '0'}
jaroslav@49:      * (<code>'&#92;u0030'</code>); otherwise, the first character of
jaroslav@49:      * the representation of the unsigned magnitude will not be the
jaroslav@49:      * zero character. The characters {@code '0'}
jaroslav@49:      * (<code>'&#92;u0030'</code>) and {@code '1'}
jaroslav@49:      * (<code>'&#92;u0031'</code>) are used as binary digits.
jaroslav@49:      *
jaroslav@49:      * @param   i   an integer to be converted to a string.
jaroslav@49:      * @return  the string representation of the unsigned integer value
jaroslav@49:      *          represented by the argument in binary (base&nbsp;2).
jaroslav@49:      * @since   JDK1.0.2
jaroslav@49:      */
jaroslav@49:     public static String toBinaryString(int i) {
jaroslav@49:         return toUnsignedString(i, 1);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Convert the integer to an unsigned number.
jaroslav@49:      */
jaroslav@49:     private static String toUnsignedString(int i, int shift) {
jaroslav@49:         char[] buf = new char[32];
jaroslav@49:         int charPos = 32;
jaroslav@49:         int radix = 1 << shift;
jaroslav@49:         int mask = radix - 1;
jaroslav@49:         do {
jaroslav@49:             buf[--charPos] = digits[i & mask];
jaroslav@49:             i >>>= shift;
jaroslav@49:         } while (i != 0);
jaroslav@49: 
jaroslav@49:         return new String(buf, charPos, (32 - charPos));
jaroslav@49:     }
jaroslav@49: 
jaroslav@49: 
jaroslav@49:     final static char [] DigitTens = {
jaroslav@49:         '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
jaroslav@49:         '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
jaroslav@49:         '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
jaroslav@49:         '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
jaroslav@49:         '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
jaroslav@49:         '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
jaroslav@49:         '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
jaroslav@49:         '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
jaroslav@49:         '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
jaroslav@49:         '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
jaroslav@49:         } ;
jaroslav@49: 
jaroslav@49:     final static char [] DigitOnes = {
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
jaroslav@49:         } ;
jaroslav@49: 
jaroslav@49:         // I use the "invariant division by multiplication" trick to
jaroslav@49:         // accelerate Integer.toString.  In particular we want to
jaroslav@49:         // avoid division by 10.
jaroslav@49:         //
jaroslav@49:         // The "trick" has roughly the same performance characteristics
jaroslav@49:         // as the "classic" Integer.toString code on a non-JIT VM.
jaroslav@49:         // The trick avoids .rem and .div calls but has a longer code
jaroslav@49:         // path and is thus dominated by dispatch overhead.  In the
jaroslav@49:         // JIT case the dispatch overhead doesn't exist and the
jaroslav@49:         // "trick" is considerably faster than the classic code.
jaroslav@49:         //
jaroslav@49:         // TODO-FIXME: convert (x * 52429) into the equiv shift-add
jaroslav@49:         // sequence.
jaroslav@49:         //
jaroslav@49:         // RE:  Division by Invariant Integers using Multiplication
jaroslav@49:         //      T Gralund, P Montgomery
jaroslav@49:         //      ACM PLDI 1994
jaroslav@49:         //
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns a {@code String} object representing the
jaroslav@49:      * specified integer. The argument is converted to signed decimal
jaroslav@49:      * representation and returned as a string, exactly as if the
jaroslav@49:      * argument and radix 10 were given as arguments to the {@link
jaroslav@49:      * #toString(int, int)} method.
jaroslav@49:      *
jaroslav@49:      * @param   i   an integer to be converted.
jaroslav@49:      * @return  a string representation of the argument in base&nbsp;10.
jaroslav@49:      */
jaroslav@49:     public static String toString(int i) {
jaroslav@49:         if (i == Integer.MIN_VALUE)
jaroslav@49:             return "-2147483648";
jaroslav@49:         int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
jaroslav@49:         char[] buf = new char[size];
jaroslav@49:         getChars(i, size, buf);
jaroslav@49:         return new String(0, size, buf);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Places characters representing the integer i into the
jaroslav@49:      * character array buf. The characters are placed into
jaroslav@49:      * the buffer backwards starting with the least significant
jaroslav@49:      * digit at the specified index (exclusive), and working
jaroslav@49:      * backwards from there.
jaroslav@49:      *
jaroslav@49:      * Will fail if i == Integer.MIN_VALUE
jaroslav@49:      */
jaroslav@49:     static void getChars(int i, int index, char[] buf) {
jaroslav@49:         int q, r;
jaroslav@49:         int charPos = index;
jaroslav@49:         char sign = 0;
jaroslav@49: 
jaroslav@49:         if (i < 0) {
jaroslav@49:             sign = '-';
jaroslav@49:             i = -i;
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         // Generate two digits per iteration
jaroslav@49:         while (i >= 65536) {
jaroslav@49:             q = i / 100;
jaroslav@49:         // really: r = i - (q * 100);
jaroslav@49:             r = i - ((q << 6) + (q << 5) + (q << 2));
jaroslav@49:             i = q;
jaroslav@49:             buf [--charPos] = DigitOnes[r];
jaroslav@49:             buf [--charPos] = DigitTens[r];
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         // Fall thru to fast mode for smaller numbers
jaroslav@49:         // assert(i <= 65536, i);
jaroslav@49:         for (;;) {
jaroslav@49:             q = (i * 52429) >>> (16+3);
jaroslav@49:             r = i - ((q << 3) + (q << 1));  // r = i-(q*10) ...
jaroslav@49:             buf [--charPos] = digits [r];
jaroslav@49:             i = q;
jaroslav@49:             if (i == 0) break;
jaroslav@49:         }
jaroslav@49:         if (sign != 0) {
jaroslav@49:             buf [--charPos] = sign;
jaroslav@49:         }
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
jaroslav@49:                                       99999999, 999999999, Integer.MAX_VALUE };
jaroslav@49: 
jaroslav@49:     // Requires positive x
jaroslav@49:     static int stringSize(int x) {
jaroslav@49:         for (int i=0; ; i++)
jaroslav@49:             if (x <= sizeTable[i])
jaroslav@49:                 return i+1;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Parses the string argument as a signed integer in the radix
jaroslav@49:      * specified by the second argument. The characters in the string
jaroslav@49:      * must all be digits of the specified radix (as determined by
jaroslav@49:      * whether {@link java.lang.Character#digit(char, int)} returns a
jaroslav@49:      * nonnegative value), except that the first character may be an
jaroslav@49:      * ASCII minus sign {@code '-'} (<code>'&#92;u002D'</code>) to
jaroslav@49:      * indicate a negative value or an ASCII plus sign {@code '+'}
jaroslav@49:      * (<code>'&#92;u002B'</code>) to indicate a positive value. The
jaroslav@49:      * resulting integer value is returned.
jaroslav@49:      *
jaroslav@49:      * <p>An exception of type {@code NumberFormatException} is
jaroslav@49:      * thrown if any of the following situations occurs:
jaroslav@49:      * <ul>
jaroslav@49:      * <li>The first argument is {@code null} or is a string of
jaroslav@49:      * length zero.
jaroslav@49:      *
jaroslav@49:      * <li>The radix is either smaller than
jaroslav@49:      * {@link java.lang.Character#MIN_RADIX} or
jaroslav@49:      * larger than {@link java.lang.Character#MAX_RADIX}.
jaroslav@49:      *
jaroslav@49:      * <li>Any character of the string is not a digit of the specified
jaroslav@49:      * radix, except that the first character may be a minus sign
jaroslav@49:      * {@code '-'} (<code>'&#92;u002D'</code>) or plus sign
jaroslav@49:      * {@code '+'} (<code>'&#92;u002B'</code>) provided that the
jaroslav@49:      * string is longer than length 1.
jaroslav@49:      *
jaroslav@49:      * <li>The value represented by the string is not a value of type
jaroslav@49:      * {@code int}.
jaroslav@49:      * </ul>
jaroslav@49:      *
jaroslav@49:      * <p>Examples:
jaroslav@49:      * <blockquote><pre>
jaroslav@49:      * parseInt("0", 10) returns 0
jaroslav@49:      * parseInt("473", 10) returns 473
jaroslav@49:      * parseInt("+42", 10) returns 42
jaroslav@49:      * parseInt("-0", 10) returns 0
jaroslav@49:      * parseInt("-FF", 16) returns -255
jaroslav@49:      * parseInt("1100110", 2) returns 102
jaroslav@49:      * parseInt("2147483647", 10) returns 2147483647
jaroslav@49:      * parseInt("-2147483648", 10) returns -2147483648
jaroslav@49:      * parseInt("2147483648", 10) throws a NumberFormatException
jaroslav@49:      * parseInt("99", 8) throws a NumberFormatException
jaroslav@49:      * parseInt("Kona", 10) throws a NumberFormatException
jaroslav@49:      * parseInt("Kona", 27) returns 411787
jaroslav@49:      * </pre></blockquote>
jaroslav@49:      *
jaroslav@49:      * @param      s   the {@code String} containing the integer
jaroslav@49:      *                  representation to be parsed
jaroslav@49:      * @param      radix   the radix to be used while parsing {@code s}.
jaroslav@49:      * @return     the integer represented by the string argument in the
jaroslav@49:      *             specified radix.
jaroslav@49:      * @exception  NumberFormatException if the {@code String}
jaroslav@49:      *             does not contain a parsable {@code int}.
jaroslav@49:      */
jaroslav@49:     public static int parseInt(String s, int radix)
jaroslav@49:                 throws NumberFormatException
jaroslav@49:     {
jaroslav@49:         /*
jaroslav@49:          * WARNING: This method may be invoked early during VM initialization
jaroslav@49:          * before IntegerCache is initialized. Care must be taken to not use
jaroslav@49:          * the valueOf method.
jaroslav@49:          */
jaroslav@49: 
jaroslav@49:         if (s == null) {
jaroslav@49:             throw new NumberFormatException("null");
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         if (radix < Character.MIN_RADIX) {
jaroslav@49:             throw new NumberFormatException("radix " + radix +
jaroslav@49:                                             " less than Character.MIN_RADIX");
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         if (radix > Character.MAX_RADIX) {
jaroslav@49:             throw new NumberFormatException("radix " + radix +
jaroslav@49:                                             " greater than Character.MAX_RADIX");
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         int result = 0;
jaroslav@49:         boolean negative = false;
jaroslav@49:         int i = 0, len = s.length();
jaroslav@49:         int limit = -Integer.MAX_VALUE;
jaroslav@49:         int multmin;
jaroslav@49:         int digit;
jaroslav@49: 
jaroslav@49:         if (len > 0) {
jaroslav@49:             char firstChar = s.charAt(0);
jaroslav@49:             if (firstChar < '0') { // Possible leading "+" or "-"
jaroslav@49:                 if (firstChar == '-') {
jaroslav@49:                     negative = true;
jaroslav@49:                     limit = Integer.MIN_VALUE;
jaroslav@49:                 } else if (firstChar != '+')
jaroslav@49:                     throw NumberFormatException.forInputString(s);
jaroslav@49: 
jaroslav@49:                 if (len == 1) // Cannot have lone "+" or "-"
jaroslav@49:                     throw NumberFormatException.forInputString(s);
jaroslav@49:                 i++;
jaroslav@49:             }
jaroslav@49:             multmin = limit / radix;
jaroslav@49:             while (i < len) {
jaroslav@49:                 // Accumulating negatively avoids surprises near MAX_VALUE
jaroslav@49:                 digit = Character.digit(s.charAt(i++),radix);
jaroslav@49:                 if (digit < 0) {
jaroslav@49:                     throw NumberFormatException.forInputString(s);
jaroslav@49:                 }
jaroslav@49:                 if (result < multmin) {
jaroslav@49:                     throw NumberFormatException.forInputString(s);
jaroslav@49:                 }
jaroslav@49:                 result *= radix;
jaroslav@49:                 if (result < limit + digit) {
jaroslav@49:                     throw NumberFormatException.forInputString(s);
jaroslav@49:                 }
jaroslav@49:                 result -= digit;
jaroslav@49:             }
jaroslav@49:         } else {
jaroslav@49:             throw NumberFormatException.forInputString(s);
jaroslav@49:         }
jaroslav@49:         return negative ? result : -result;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Parses the string argument as a signed decimal integer. The
jaroslav@49:      * characters in the string must all be decimal digits, except
jaroslav@49:      * that the first character may be an ASCII minus sign {@code '-'}
jaroslav@49:      * (<code>'&#92;u002D'</code>) to indicate a negative value or an
jaroslav@49:      * ASCII plus sign {@code '+'} (<code>'&#92;u002B'</code>) to
jaroslav@49:      * indicate a positive value. The resulting integer value is
jaroslav@49:      * returned, exactly as if the argument and the radix 10 were
jaroslav@49:      * given as arguments to the {@link #parseInt(java.lang.String,
jaroslav@49:      * int)} method.
jaroslav@49:      *
jaroslav@49:      * @param s    a {@code String} containing the {@code int}
jaroslav@49:      *             representation to be parsed
jaroslav@49:      * @return     the integer value represented by the argument in decimal.
jaroslav@49:      * @exception  NumberFormatException  if the string does not contain a
jaroslav@49:      *               parsable integer.
jaroslav@49:      */
jaroslav@49:     public static int parseInt(String s) throws NumberFormatException {
jaroslav@49:         return parseInt(s,10);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns an {@code Integer} object holding the value
jaroslav@49:      * extracted from the specified {@code String} when parsed
jaroslav@49:      * with the radix given by the second argument. The first argument
jaroslav@49:      * is interpreted as representing a signed integer in the radix
jaroslav@49:      * specified by the second argument, exactly as if the arguments
jaroslav@49:      * were given to the {@link #parseInt(java.lang.String, int)}
jaroslav@49:      * method. The result is an {@code Integer} object that
jaroslav@49:      * represents the integer value specified by the string.
jaroslav@49:      *
jaroslav@49:      * <p>In other words, this method returns an {@code Integer}
jaroslav@49:      * object equal to the value of:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *  {@code new Integer(Integer.parseInt(s, radix))}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * @param      s   the string to be parsed.
jaroslav@49:      * @param      radix the radix to be used in interpreting {@code s}
jaroslav@49:      * @return     an {@code Integer} object holding the value
jaroslav@49:      *             represented by the string argument in the specified
jaroslav@49:      *             radix.
jaroslav@49:      * @exception NumberFormatException if the {@code String}
jaroslav@49:      *            does not contain a parsable {@code int}.
jaroslav@49:      */
jaroslav@49:     public static Integer valueOf(String s, int radix) throws NumberFormatException {
jaroslav@49:         return Integer.valueOf(parseInt(s,radix));
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns an {@code Integer} object holding the
jaroslav@49:      * value of the specified {@code String}. The argument is
jaroslav@49:      * interpreted as representing a signed decimal integer, exactly
jaroslav@49:      * as if the argument were given to the {@link
jaroslav@49:      * #parseInt(java.lang.String)} method. The result is an
jaroslav@49:      * {@code Integer} object that represents the integer value
jaroslav@49:      * specified by the string.
jaroslav@49:      *
jaroslav@49:      * <p>In other words, this method returns an {@code Integer}
jaroslav@49:      * object equal to the value of:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *  {@code new Integer(Integer.parseInt(s))}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * @param      s   the string to be parsed.
jaroslav@49:      * @return     an {@code Integer} object holding the value
jaroslav@49:      *             represented by the string argument.
jaroslav@49:      * @exception  NumberFormatException  if the string cannot be parsed
jaroslav@49:      *             as an integer.
jaroslav@49:      */
jaroslav@49:     public static Integer valueOf(String s) throws NumberFormatException {
jaroslav@49:         return Integer.valueOf(parseInt(s, 10));
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Cache to support the object identity semantics of autoboxing for values between
jaroslav@49:      * -128 and 127 (inclusive) as required by JLS.
jaroslav@49:      *
jaroslav@49:      * The cache is initialized on first usage.  The size of the cache
jaroslav@49:      * may be controlled by the -XX:AutoBoxCacheMax=<size> option.
jaroslav@49:      * During VM initialization, java.lang.Integer.IntegerCache.high property
jaroslav@49:      * may be set and saved in the private system properties in the
jaroslav@49:      * sun.misc.VM class.
jaroslav@49:      */
jaroslav@49: 
jaroslav@49:     private static class IntegerCache {
jaroslav@49:         static final int low = -128;
jaroslav@49:         static final int high;
jaroslav@49:         static final Integer cache[];
jaroslav@49: 
jaroslav@49:         static {
jaroslav@49:             // high value may be configured by property
jaroslav@49:             int h = 127;
jaroslav@49:             String integerCacheHighPropValue =
jaroslav@49:                 sun.misc.VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
jaroslav@49:             if (integerCacheHighPropValue != null) {
jaroslav@49:                 int i = parseInt(integerCacheHighPropValue);
jaroslav@49:                 i = Math.max(i, 127);
jaroslav@49:                 // Maximum array size is Integer.MAX_VALUE
jaroslav@49:                 h = Math.min(i, Integer.MAX_VALUE - (-low));
jaroslav@49:             }
jaroslav@49:             high = h;
jaroslav@49: 
jaroslav@49:             cache = new Integer[(high - low) + 1];
jaroslav@49:             int j = low;
jaroslav@49:             for(int k = 0; k < cache.length; k++)
jaroslav@49:                 cache[k] = new Integer(j++);
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         private IntegerCache() {}
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns an {@code Integer} instance representing the specified
jaroslav@49:      * {@code int} value.  If a new {@code Integer} instance is not
jaroslav@49:      * required, this method should generally be used in preference to
jaroslav@49:      * the constructor {@link #Integer(int)}, as this method is likely
jaroslav@49:      * to yield significantly better space and time performance by
jaroslav@49:      * caching frequently requested values.
jaroslav@49:      *
jaroslav@49:      * This method will always cache values in the range -128 to 127,
jaroslav@49:      * inclusive, and may cache other values outside of this range.
jaroslav@49:      *
jaroslav@49:      * @param  i an {@code int} value.
jaroslav@49:      * @return an {@code Integer} instance representing {@code i}.
jaroslav@49:      * @since  1.5
jaroslav@49:      */
jaroslav@49:     public static Integer valueOf(int i) {
jaroslav@49:         assert IntegerCache.high >= 127;
jaroslav@49:         if (i >= IntegerCache.low && i <= IntegerCache.high)
jaroslav@49:             return IntegerCache.cache[i + (-IntegerCache.low)];
jaroslav@49:         return new Integer(i);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * The value of the {@code Integer}.
jaroslav@49:      *
jaroslav@49:      * @serial
jaroslav@49:      */
jaroslav@49:     private final int value;
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Constructs a newly allocated {@code Integer} object that
jaroslav@49:      * represents the specified {@code int} value.
jaroslav@49:      *
jaroslav@49:      * @param   value   the value to be represented by the
jaroslav@49:      *                  {@code Integer} object.
jaroslav@49:      */
jaroslav@49:     public Integer(int value) {
jaroslav@49:         this.value = value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Constructs a newly allocated {@code Integer} object that
jaroslav@49:      * represents the {@code int} value indicated by the
jaroslav@49:      * {@code String} parameter. The string is converted to an
jaroslav@49:      * {@code int} value in exactly the manner used by the
jaroslav@49:      * {@code parseInt} method for radix 10.
jaroslav@49:      *
jaroslav@49:      * @param      s   the {@code String} to be converted to an
jaroslav@49:      *                 {@code Integer}.
jaroslav@49:      * @exception  NumberFormatException  if the {@code String} does not
jaroslav@49:      *               contain a parsable integer.
jaroslav@49:      * @see        java.lang.Integer#parseInt(java.lang.String, int)
jaroslav@49:      */
jaroslav@49:     public Integer(String s) throws NumberFormatException {
jaroslav@49:         this.value = parseInt(s, 10);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value of this {@code Integer} as a
jaroslav@49:      * {@code byte}.
jaroslav@49:      */
jaroslav@49:     public byte byteValue() {
jaroslav@49:         return (byte)value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value of this {@code Integer} as a
jaroslav@49:      * {@code short}.
jaroslav@49:      */
jaroslav@49:     public short shortValue() {
jaroslav@49:         return (short)value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value of this {@code Integer} as an
jaroslav@49:      * {@code int}.
jaroslav@49:      */
jaroslav@49:     public int intValue() {
jaroslav@49:         return value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value of this {@code Integer} as a
jaroslav@49:      * {@code long}.
jaroslav@49:      */
jaroslav@49:     public long longValue() {
jaroslav@49:         return (long)value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value of this {@code Integer} as a
jaroslav@49:      * {@code float}.
jaroslav@49:      */
jaroslav@49:     public float floatValue() {
jaroslav@49:         return (float)value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value of this {@code Integer} as a
jaroslav@49:      * {@code double}.
jaroslav@49:      */
jaroslav@49:     public double doubleValue() {
jaroslav@49:         return (double)value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns a {@code String} object representing this
jaroslav@49:      * {@code Integer}'s value. The value is converted to signed
jaroslav@49:      * decimal representation and returned as a string, exactly as if
jaroslav@49:      * the integer value were given as an argument to the {@link
jaroslav@49:      * java.lang.Integer#toString(int)} method.
jaroslav@49:      *
jaroslav@49:      * @return  a string representation of the value of this object in
jaroslav@49:      *          base&nbsp;10.
jaroslav@49:      */
jaroslav@49:     public String toString() {
jaroslav@49:         return toString(value);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns a hash code for this {@code Integer}.
jaroslav@49:      *
jaroslav@49:      * @return  a hash code value for this object, equal to the
jaroslav@49:      *          primitive {@code int} value represented by this
jaroslav@49:      *          {@code Integer} object.
jaroslav@49:      */
jaroslav@49:     public int hashCode() {
jaroslav@49:         return value;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Compares this object to the specified object.  The result is
jaroslav@49:      * {@code true} if and only if the argument is not
jaroslav@49:      * {@code null} and is an {@code Integer} object that
jaroslav@49:      * contains the same {@code int} value as this object.
jaroslav@49:      *
jaroslav@49:      * @param   obj   the object to compare with.
jaroslav@49:      * @return  {@code true} if the objects are the same;
jaroslav@49:      *          {@code false} otherwise.
jaroslav@49:      */
jaroslav@49:     public boolean equals(Object obj) {
jaroslav@49:         if (obj instanceof Integer) {
jaroslav@49:             return value == ((Integer)obj).intValue();
jaroslav@49:         }
jaroslav@49:         return false;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Determines the integer value of the system property with the
jaroslav@49:      * specified name.
jaroslav@49:      *
jaroslav@49:      * <p>The first argument is treated as the name of a system property.
jaroslav@49:      * System properties are accessible through the
jaroslav@49:      * {@link java.lang.System#getProperty(java.lang.String)} method. The
jaroslav@49:      * string value of this property is then interpreted as an integer
jaroslav@49:      * value and an {@code Integer} object representing this value is
jaroslav@49:      * returned. Details of possible numeric formats can be found with
jaroslav@49:      * the definition of {@code getProperty}.
jaroslav@49:      *
jaroslav@49:      * <p>If there is no property with the specified name, if the specified name
jaroslav@49:      * is empty or {@code null}, or if the property does not have
jaroslav@49:      * the correct numeric format, then {@code null} is returned.
jaroslav@49:      *
jaroslav@49:      * <p>In other words, this method returns an {@code Integer}
jaroslav@49:      * object equal to the value of:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *  {@code getInteger(nm, null)}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * @param   nm   property name.
jaroslav@49:      * @return  the {@code Integer} value of the property.
jaroslav@49:      * @see     java.lang.System#getProperty(java.lang.String)
jaroslav@49:      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
jaroslav@49:      */
jaroslav@49:     public static Integer getInteger(String nm) {
jaroslav@49:         return getInteger(nm, null);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Determines the integer value of the system property with the
jaroslav@49:      * specified name.
jaroslav@49:      *
jaroslav@49:      * <p>The first argument is treated as the name of a system property.
jaroslav@49:      * System properties are accessible through the {@link
jaroslav@49:      * java.lang.System#getProperty(java.lang.String)} method. The
jaroslav@49:      * string value of this property is then interpreted as an integer
jaroslav@49:      * value and an {@code Integer} object representing this value is
jaroslav@49:      * returned. Details of possible numeric formats can be found with
jaroslav@49:      * the definition of {@code getProperty}.
jaroslav@49:      *
jaroslav@49:      * <p>The second argument is the default value. An {@code Integer} object
jaroslav@49:      * that represents the value of the second argument is returned if there
jaroslav@49:      * is no property of the specified name, if the property does not have
jaroslav@49:      * the correct numeric format, or if the specified name is empty or
jaroslav@49:      * {@code null}.
jaroslav@49:      *
jaroslav@49:      * <p>In other words, this method returns an {@code Integer} object
jaroslav@49:      * equal to the value of:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      *  {@code getInteger(nm, new Integer(val))}
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * but in practice it may be implemented in a manner such as:
jaroslav@49:      *
jaroslav@49:      * <blockquote><pre>
jaroslav@49:      * Integer result = getInteger(nm, null);
jaroslav@49:      * return (result == null) ? new Integer(val) : result;
jaroslav@49:      * </pre></blockquote>
jaroslav@49:      *
jaroslav@49:      * to avoid the unnecessary allocation of an {@code Integer}
jaroslav@49:      * object when the default value is not needed.
jaroslav@49:      *
jaroslav@49:      * @param   nm   property name.
jaroslav@49:      * @param   val   default value.
jaroslav@49:      * @return  the {@code Integer} value of the property.
jaroslav@49:      * @see     java.lang.System#getProperty(java.lang.String)
jaroslav@49:      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
jaroslav@49:      */
jaroslav@49:     public static Integer getInteger(String nm, int val) {
jaroslav@49:         Integer result = getInteger(nm, null);
jaroslav@49:         return (result == null) ? Integer.valueOf(val) : result;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the integer value of the system property with the
jaroslav@49:      * specified name.  The first argument is treated as the name of a
jaroslav@49:      * system property.  System properties are accessible through the
jaroslav@49:      * {@link java.lang.System#getProperty(java.lang.String)} method.
jaroslav@49:      * The string value of this property is then interpreted as an
jaroslav@49:      * integer value, as per the {@code Integer.decode} method,
jaroslav@49:      * and an {@code Integer} object representing this value is
jaroslav@49:      * returned.
jaroslav@49:      *
jaroslav@49:      * <ul><li>If the property value begins with the two ASCII characters
jaroslav@49:      *         {@code 0x} or the ASCII character {@code #}, not
jaroslav@49:      *      followed by a minus sign, then the rest of it is parsed as a
jaroslav@49:      *      hexadecimal integer exactly as by the method
jaroslav@49:      *      {@link #valueOf(java.lang.String, int)} with radix 16.
jaroslav@49:      * <li>If the property value begins with the ASCII character
jaroslav@49:      *     {@code 0} followed by another character, it is parsed as an
jaroslav@49:      *     octal integer exactly as by the method
jaroslav@49:      *     {@link #valueOf(java.lang.String, int)} with radix 8.
jaroslav@49:      * <li>Otherwise, the property value is parsed as a decimal integer
jaroslav@49:      * exactly as by the method {@link #valueOf(java.lang.String, int)}
jaroslav@49:      * with radix 10.
jaroslav@49:      * </ul>
jaroslav@49:      *
jaroslav@49:      * <p>The second argument is the default value. The default value is
jaroslav@49:      * returned if there is no property of the specified name, if the
jaroslav@49:      * property does not have the correct numeric format, or if the
jaroslav@49:      * specified name is empty or {@code null}.
jaroslav@49:      *
jaroslav@49:      * @param   nm   property name.
jaroslav@49:      * @param   val   default value.
jaroslav@49:      * @return  the {@code Integer} value of the property.
jaroslav@49:      * @see     java.lang.System#getProperty(java.lang.String)
jaroslav@49:      * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
jaroslav@49:      * @see java.lang.Integer#decode
jaroslav@49:      */
jaroslav@49:     public static Integer getInteger(String nm, Integer val) {
jaroslav@49:         String v = null;
jaroslav@49:         try {
jaroslav@49:             v = System.getProperty(nm);
jaroslav@49:         } catch (IllegalArgumentException e) {
jaroslav@49:         } catch (NullPointerException e) {
jaroslav@49:         }
jaroslav@49:         if (v != null) {
jaroslav@49:             try {
jaroslav@49:                 return Integer.decode(v);
jaroslav@49:             } catch (NumberFormatException e) {
jaroslav@49:             }
jaroslav@49:         }
jaroslav@49:         return val;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Decodes a {@code String} into an {@code Integer}.
jaroslav@49:      * Accepts decimal, hexadecimal, and octal numbers given
jaroslav@49:      * by the following grammar:
jaroslav@49:      *
jaroslav@49:      * <blockquote>
jaroslav@49:      * <dl>
jaroslav@49:      * <dt><i>DecodableString:</i>
jaroslav@49:      * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
jaroslav@49:      * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
jaroslav@49:      * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
jaroslav@49:      * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
jaroslav@49:      * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
jaroslav@49:      * <p>
jaroslav@49:      * <dt><i>Sign:</i>
jaroslav@49:      * <dd>{@code -}
jaroslav@49:      * <dd>{@code +}
jaroslav@49:      * </dl>
jaroslav@49:      * </blockquote>
jaroslav@49:      *
jaroslav@49:      * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
jaroslav@49:      * are as defined in section 3.10.1 of
jaroslav@49:      * <cite>The Java&trade; Language Specification</cite>,
jaroslav@49:      * except that underscores are not accepted between digits.
jaroslav@49:      *
jaroslav@49:      * <p>The sequence of characters following an optional
jaroslav@49:      * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
jaroslav@49:      * "{@code #}", or leading zero) is parsed as by the {@code
jaroslav@49:      * Integer.parseInt} method with the indicated radix (10, 16, or
jaroslav@49:      * 8).  This sequence of characters must represent a positive
jaroslav@49:      * value or a {@link NumberFormatException} will be thrown.  The
jaroslav@49:      * result is negated if first character of the specified {@code
jaroslav@49:      * String} is the minus sign.  No whitespace characters are
jaroslav@49:      * permitted in the {@code String}.
jaroslav@49:      *
jaroslav@49:      * @param     nm the {@code String} to decode.
jaroslav@49:      * @return    an {@code Integer} object holding the {@code int}
jaroslav@49:      *             value represented by {@code nm}
jaroslav@49:      * @exception NumberFormatException  if the {@code String} does not
jaroslav@49:      *            contain a parsable integer.
jaroslav@49:      * @see java.lang.Integer#parseInt(java.lang.String, int)
jaroslav@49:      */
jaroslav@49:     public static Integer decode(String nm) throws NumberFormatException {
jaroslav@49:         int radix = 10;
jaroslav@49:         int index = 0;
jaroslav@49:         boolean negative = false;
jaroslav@49:         Integer result;
jaroslav@49: 
jaroslav@49:         if (nm.length() == 0)
jaroslav@49:             throw new NumberFormatException("Zero length string");
jaroslav@49:         char firstChar = nm.charAt(0);
jaroslav@49:         // Handle sign, if present
jaroslav@49:         if (firstChar == '-') {
jaroslav@49:             negative = true;
jaroslav@49:             index++;
jaroslav@49:         } else if (firstChar == '+')
jaroslav@49:             index++;
jaroslav@49: 
jaroslav@49:         // Handle radix specifier, if present
jaroslav@49:         if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
jaroslav@49:             index += 2;
jaroslav@49:             radix = 16;
jaroslav@49:         }
jaroslav@49:         else if (nm.startsWith("#", index)) {
jaroslav@49:             index ++;
jaroslav@49:             radix = 16;
jaroslav@49:         }
jaroslav@49:         else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
jaroslav@49:             index ++;
jaroslav@49:             radix = 8;
jaroslav@49:         }
jaroslav@49: 
jaroslav@49:         if (nm.startsWith("-", index) || nm.startsWith("+", index))
jaroslav@49:             throw new NumberFormatException("Sign character in wrong position");
jaroslav@49: 
jaroslav@49:         try {
jaroslav@49:             result = Integer.valueOf(nm.substring(index), radix);
jaroslav@49:             result = negative ? Integer.valueOf(-result.intValue()) : result;
jaroslav@49:         } catch (NumberFormatException e) {
jaroslav@49:             // If number is Integer.MIN_VALUE, we'll end up here. The next line
jaroslav@49:             // handles this case, and causes any genuine format error to be
jaroslav@49:             // rethrown.
jaroslav@49:             String constant = negative ? ("-" + nm.substring(index))
jaroslav@49:                                        : nm.substring(index);
jaroslav@49:             result = Integer.valueOf(constant, radix);
jaroslav@49:         }
jaroslav@49:         return result;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Compares two {@code Integer} objects numerically.
jaroslav@49:      *
jaroslav@49:      * @param   anotherInteger   the {@code Integer} to be compared.
jaroslav@49:      * @return  the value {@code 0} if this {@code Integer} is
jaroslav@49:      *          equal to the argument {@code Integer}; a value less than
jaroslav@49:      *          {@code 0} if this {@code Integer} is numerically less
jaroslav@49:      *          than the argument {@code Integer}; and a value greater
jaroslav@49:      *          than {@code 0} if this {@code Integer} is numerically
jaroslav@49:      *           greater than the argument {@code Integer} (signed
jaroslav@49:      *           comparison).
jaroslav@49:      * @since   1.2
jaroslav@49:      */
jaroslav@49:     public int compareTo(Integer anotherInteger) {
jaroslav@49:         return compare(this.value, anotherInteger.value);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Compares two {@code int} values numerically.
jaroslav@49:      * The value returned is identical to what would be returned by:
jaroslav@49:      * <pre>
jaroslav@49:      *    Integer.valueOf(x).compareTo(Integer.valueOf(y))
jaroslav@49:      * </pre>
jaroslav@49:      *
jaroslav@49:      * @param  x the first {@code int} to compare
jaroslav@49:      * @param  y the second {@code int} to compare
jaroslav@49:      * @return the value {@code 0} if {@code x == y};
jaroslav@49:      *         a value less than {@code 0} if {@code x < y}; and
jaroslav@49:      *         a value greater than {@code 0} if {@code x > y}
jaroslav@49:      * @since 1.7
jaroslav@49:      */
jaroslav@49:     public static int compare(int x, int y) {
jaroslav@49:         return (x < y) ? -1 : ((x == y) ? 0 : 1);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49: 
jaroslav@49:     // Bit twiddling
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * The number of bits used to represent an {@code int} value in two's
jaroslav@49:      * complement binary form.
jaroslav@49:      *
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static final int SIZE = 32;
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns an {@code int} value with at most a single one-bit, in the
jaroslav@49:      * position of the highest-order ("leftmost") one-bit in the specified
jaroslav@49:      * {@code int} value.  Returns zero if the specified value has no
jaroslav@49:      * one-bits in its two's complement binary representation, that is, if it
jaroslav@49:      * is equal to zero.
jaroslav@49:      *
jaroslav@49:      * @return an {@code int} value with a single one-bit, in the position
jaroslav@49:      *     of the highest-order one-bit in the specified value, or zero if
jaroslav@49:      *     the specified value is itself equal to zero.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int highestOneBit(int i) {
jaroslav@49:         // HD, Figure 3-1
jaroslav@49:         i |= (i >>  1);
jaroslav@49:         i |= (i >>  2);
jaroslav@49:         i |= (i >>  4);
jaroslav@49:         i |= (i >>  8);
jaroslav@49:         i |= (i >> 16);
jaroslav@49:         return i - (i >>> 1);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns an {@code int} value with at most a single one-bit, in the
jaroslav@49:      * position of the lowest-order ("rightmost") one-bit in the specified
jaroslav@49:      * {@code int} value.  Returns zero if the specified value has no
jaroslav@49:      * one-bits in its two's complement binary representation, that is, if it
jaroslav@49:      * is equal to zero.
jaroslav@49:      *
jaroslav@49:      * @return an {@code int} value with a single one-bit, in the position
jaroslav@49:      *     of the lowest-order one-bit in the specified value, or zero if
jaroslav@49:      *     the specified value is itself equal to zero.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int lowestOneBit(int i) {
jaroslav@49:         // HD, Section 2-1
jaroslav@49:         return i & -i;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the number of zero bits preceding the highest-order
jaroslav@49:      * ("leftmost") one-bit in the two's complement binary representation
jaroslav@49:      * of the specified {@code int} value.  Returns 32 if the
jaroslav@49:      * specified value has no one-bits in its two's complement representation,
jaroslav@49:      * in other words if it is equal to zero.
jaroslav@49:      *
jaroslav@49:      * <p>Note that this method is closely related to the logarithm base 2.
jaroslav@49:      * For all positive {@code int} values x:
jaroslav@49:      * <ul>
jaroslav@49:      * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
jaroslav@49:      * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
jaroslav@49:      * </ul>
jaroslav@49:      *
jaroslav@49:      * @return the number of zero bits preceding the highest-order
jaroslav@49:      *     ("leftmost") one-bit in the two's complement binary representation
jaroslav@49:      *     of the specified {@code int} value, or 32 if the value
jaroslav@49:      *     is equal to zero.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int numberOfLeadingZeros(int i) {
jaroslav@49:         // HD, Figure 5-6
jaroslav@49:         if (i == 0)
jaroslav@49:             return 32;
jaroslav@49:         int n = 1;
jaroslav@49:         if (i >>> 16 == 0) { n += 16; i <<= 16; }
jaroslav@49:         if (i >>> 24 == 0) { n +=  8; i <<=  8; }
jaroslav@49:         if (i >>> 28 == 0) { n +=  4; i <<=  4; }
jaroslav@49:         if (i >>> 30 == 0) { n +=  2; i <<=  2; }
jaroslav@49:         n -= i >>> 31;
jaroslav@49:         return n;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the number of zero bits following the lowest-order ("rightmost")
jaroslav@49:      * one-bit in the two's complement binary representation of the specified
jaroslav@49:      * {@code int} value.  Returns 32 if the specified value has no
jaroslav@49:      * one-bits in its two's complement representation, in other words if it is
jaroslav@49:      * equal to zero.
jaroslav@49:      *
jaroslav@49:      * @return the number of zero bits following the lowest-order ("rightmost")
jaroslav@49:      *     one-bit in the two's complement binary representation of the
jaroslav@49:      *     specified {@code int} value, or 32 if the value is equal
jaroslav@49:      *     to zero.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int numberOfTrailingZeros(int i) {
jaroslav@49:         // HD, Figure 5-14
jaroslav@49:         int y;
jaroslav@49:         if (i == 0) return 32;
jaroslav@49:         int n = 31;
jaroslav@49:         y = i <<16; if (y != 0) { n = n -16; i = y; }
jaroslav@49:         y = i << 8; if (y != 0) { n = n - 8; i = y; }
jaroslav@49:         y = i << 4; if (y != 0) { n = n - 4; i = y; }
jaroslav@49:         y = i << 2; if (y != 0) { n = n - 2; i = y; }
jaroslav@49:         return n - ((i << 1) >>> 31);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the number of one-bits in the two's complement binary
jaroslav@49:      * representation of the specified {@code int} value.  This function is
jaroslav@49:      * sometimes referred to as the <i>population count</i>.
jaroslav@49:      *
jaroslav@49:      * @return the number of one-bits in the two's complement binary
jaroslav@49:      *     representation of the specified {@code int} value.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int bitCount(int i) {
jaroslav@49:         // HD, Figure 5-2
jaroslav@49:         i = i - ((i >>> 1) & 0x55555555);
jaroslav@49:         i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
jaroslav@49:         i = (i + (i >>> 4)) & 0x0f0f0f0f;
jaroslav@49:         i = i + (i >>> 8);
jaroslav@49:         i = i + (i >>> 16);
jaroslav@49:         return i & 0x3f;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value obtained by rotating the two's complement binary
jaroslav@49:      * representation of the specified {@code int} value left by the
jaroslav@49:      * specified number of bits.  (Bits shifted out of the left hand, or
jaroslav@49:      * high-order, side reenter on the right, or low-order.)
jaroslav@49:      *
jaroslav@49:      * <p>Note that left rotation with a negative distance is equivalent to
jaroslav@49:      * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
jaroslav@49:      * distance)}.  Note also that rotation by any multiple of 32 is a
jaroslav@49:      * no-op, so all but the last five bits of the rotation distance can be
jaroslav@49:      * ignored, even if the distance is negative: {@code rotateLeft(val,
jaroslav@49:      * distance) == rotateLeft(val, distance & 0x1F)}.
jaroslav@49:      *
jaroslav@49:      * @return the value obtained by rotating the two's complement binary
jaroslav@49:      *     representation of the specified {@code int} value left by the
jaroslav@49:      *     specified number of bits.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int rotateLeft(int i, int distance) {
jaroslav@49:         return (i << distance) | (i >>> -distance);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value obtained by rotating the two's complement binary
jaroslav@49:      * representation of the specified {@code int} value right by the
jaroslav@49:      * specified number of bits.  (Bits shifted out of the right hand, or
jaroslav@49:      * low-order, side reenter on the left, or high-order.)
jaroslav@49:      *
jaroslav@49:      * <p>Note that right rotation with a negative distance is equivalent to
jaroslav@49:      * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
jaroslav@49:      * distance)}.  Note also that rotation by any multiple of 32 is a
jaroslav@49:      * no-op, so all but the last five bits of the rotation distance can be
jaroslav@49:      * ignored, even if the distance is negative: {@code rotateRight(val,
jaroslav@49:      * distance) == rotateRight(val, distance & 0x1F)}.
jaroslav@49:      *
jaroslav@49:      * @return the value obtained by rotating the two's complement binary
jaroslav@49:      *     representation of the specified {@code int} value right by the
jaroslav@49:      *     specified number of bits.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int rotateRight(int i, int distance) {
jaroslav@49:         return (i >>> distance) | (i << -distance);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value obtained by reversing the order of the bits in the
jaroslav@49:      * two's complement binary representation of the specified {@code int}
jaroslav@49:      * value.
jaroslav@49:      *
jaroslav@49:      * @return the value obtained by reversing order of the bits in the
jaroslav@49:      *     specified {@code int} value.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int reverse(int i) {
jaroslav@49:         // HD, Figure 7-1
jaroslav@49:         i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
jaroslav@49:         i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
jaroslav@49:         i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
jaroslav@49:         i = (i << 24) | ((i & 0xff00) << 8) |
jaroslav@49:             ((i >>> 8) & 0xff00) | (i >>> 24);
jaroslav@49:         return i;
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the signum function of the specified {@code int} value.  (The
jaroslav@49:      * return value is -1 if the specified value is negative; 0 if the
jaroslav@49:      * specified value is zero; and 1 if the specified value is positive.)
jaroslav@49:      *
jaroslav@49:      * @return the signum function of the specified {@code int} value.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int signum(int i) {
jaroslav@49:         // HD, Section 2-7
jaroslav@49:         return (i >> 31) | (-i >>> 31);
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /**
jaroslav@49:      * Returns the value obtained by reversing the order of the bytes in the
jaroslav@49:      * two's complement representation of the specified {@code int} value.
jaroslav@49:      *
jaroslav@49:      * @return the value obtained by reversing the bytes in the specified
jaroslav@49:      *     {@code int} value.
jaroslav@49:      * @since 1.5
jaroslav@49:      */
jaroslav@49:     public static int reverseBytes(int i) {
jaroslav@49:         return ((i >>> 24)           ) |
jaroslav@49:                ((i >>   8) &   0xFF00) |
jaroslav@49:                ((i <<   8) & 0xFF0000) |
jaroslav@49:                ((i << 24));
jaroslav@49:     }
jaroslav@49: 
jaroslav@49:     /** use serialVersionUID from JDK 1.0.2 for interoperability */
jaroslav@49:     private static final long serialVersionUID = 1360826667806852920L;
jaroslav@49: }