/*
 * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.lang;

import java.util.Properties;

/**
 * The {@code Integer} class wraps a value of the primitive type
 * {@code int} in an object. An object of type {@code Integer}
 * contains a single field whose type is {@code int}.
 *
 * <p>In addition, this class provides several methods for converting
 * an {@code int} to a {@code String} and a {@code String} to an
 * {@code int}, as well as other constants and methods useful when
 * dealing with an {@code int}.
 *
 * <p>Implementation note: The implementations of the "bit twiddling"
 * methods (such as {@link #highestOneBit(int) highestOneBit} and
 * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
 * Delight</i>, (Addison Wesley, 2002).
 *
 * @author  Lee Boynton
 * @author  Arthur van Hoff
 * @author  Josh Bloch
 * @author  Joseph D. Darcy
 * @since JDK1.0
 */
public final class Integer extends Number implements Comparable<Integer> {
	/**
	 * A constant holding the minimum value an {@code int} can
	 * have, -2<sup>31</sup>.
	 */
	public static final int   MIN_VALUE = 0x80000000;

	/**
	 * A constant holding the maximum value an {@code int} can
	 * have, 2<sup>31</sup>-1.
	 */
	public static final int   MAX_VALUE = 0x7fffffff;

	/*
	 * NANITE: This is a change from OpenJDK in that the class type is setup by the linker so we don't create it here
	 */

	/**
	 * The {@code Class} instance representing the primitive type
	 * {@code int}.
	 *
	 * @since   JDK1.1
	 */
	public static final Class<Integer>  TYPE = null;

	/**
	 * All possible chars for representing a number as a String
	 */
	final static char[] digits = {
			'0' , '1' , '2' , '3' , '4' , '5' ,
			'6' , '7' , '8' , '9' , 'a' , 'b' ,
			'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
			'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
			'o' , 'p' , 'q' , 'r' , 's' , 't' ,
			'u' , 'v' , 'w' , 'x' , 'y' , 'z'
	};

	/**
	 * Returns a string representation of the first argument in the
	 * radix specified by the second argument.
	 *
	 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
	 * or larger than {@code Character.MAX_RADIX}, then the radix
	 * {@code 10} is used instead.
	 *
	 * <p>If the first argument is negative, the first element of the
	 * result is the ASCII minus character {@code '-'}
	 * (<code>'&#92;u002D'</code>). If the first argument is not
	 * negative, no sign character appears in the result.
	 *
	 * <p>The remaining characters of the result represent the magnitude
	 * of the first argument. If the magnitude is zero, it is
	 * represented by a single zero character {@code '0'}
	 * (<code>'&#92;u0030'</code>); otherwise, the first character of
	 * the representation of the magnitude will not be the zero
	 * character.  The following ASCII characters are used as digits:
	 *
	 * <blockquote>
	 *   {@code 0123456789abcdefghijklmnopqrstuvwxyz}
	 * </blockquote>
	 *
	 * These are <code>'&#92;u0030'</code> through
	 * <code>'&#92;u0039'</code> and <code>'&#92;u0061'</code> through
	 * <code>'&#92;u007A'</code>. If {@code radix} is
	 * <var>N</var>, then the first <var>N</var> of these characters
	 * are used as radix-<var>N</var> digits in the order shown. Thus,
	 * the digits for hexadecimal (radix 16) are
	 * {@code 0123456789abcdef}. If uppercase letters are
	 * desired, the {@link java.lang.String#toUpperCase()} method may
	 * be called on the result:
	 *
	 * <blockquote>
	 *  {@code Integer.toString(n, 16).toUpperCase()}
	 * </blockquote>
	 *
	 * @param   i       an integer to be converted to a string.
	 * @param   radix   the radix to use in the string representation.
	 * @return  a string representation of the argument in the specified radix.
	 * @see     java.lang.Character#MAX_RADIX
	 * @see     java.lang.Character#MIN_RADIX
	 */
	public static String toString(int i, int radix) {

		if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
			radix = 10;

        /* Use the faster version */
		if (radix == 10) {
			return toString(i);
		}

		char buf[] = new char[33];
		boolean negative = (i < 0);
		int charPos = 32;

		if (!negative) {
			i = -i;
		}

		while (i <= -radix) {
			buf[charPos--] = digits[-(i % radix)];
			i = i / radix;
		}
		buf[charPos] = digits[-i];

		if (negative) {
			buf[--charPos] = '-';
		}

		return new String(buf, charPos, (33 - charPos));
	}

	/**
	 * Returns a string representation of the integer argument as an
	 * unsigned integer in base&nbsp;16.
	 *
	 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
	 * if the argument is negative; otherwise, it is equal to the
	 * argument.  This value is converted to a string of ASCII digits
	 * in hexadecimal (base&nbsp;16) with no extra leading
	 * {@code 0}s. If the unsigned magnitude is zero, it is
	 * represented by a single zero character {@code '0'}
	 * (<code>'&#92;u0030'</code>); otherwise, the first character of
	 * the representation of the unsigned magnitude will not be the
	 * zero character. The following characters are used as
	 * hexadecimal digits:
	 *
	 * <blockquote>
	 *  {@code 0123456789abcdef}
	 * </blockquote>
	 *
	 * These are the characters <code>'&#92;u0030'</code> through
	 * <code>'&#92;u0039'</code> and <code>'&#92;u0061'</code> through
	 * <code>'&#92;u0066'</code>. If uppercase letters are
	 * desired, the {@link java.lang.String#toUpperCase()} method may
	 * be called on the result:
	 *
	 * <blockquote>
	 *  {@code Integer.toHexString(n).toUpperCase()}
	 * </blockquote>
	 *
	 * @param   i   an integer to be converted to a string.
	 * @return  the string representation of the unsigned integer value
	 *          represented by the argument in hexadecimal (base&nbsp;16).
	 * @since   JDK1.0.2
	 */
	public static String toHexString(int i) {
		return toUnsignedString(i, 4);
	}

	/**
	 * Returns a string representation of the integer argument as an
	 * unsigned integer in base&nbsp;8.
	 *
	 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
	 * if the argument is negative; otherwise, it is equal to the
	 * argument.  This value is converted to a string of ASCII digits
	 * in octal (base&nbsp;8) with no extra leading {@code 0}s.
	 *
	 * <p>If the unsigned magnitude is zero, it is represented by a
	 * single zero character {@code '0'}
	 * (<code>'&#92;u0030'</code>); otherwise, the first character of
	 * the representation of the unsigned magnitude will not be the
	 * zero character. The following characters are used as octal
	 * digits:
	 *
	 * <blockquote>
	 * {@code 01234567}
	 * </blockquote>
	 *
	 * These are the characters <code>'&#92;u0030'</code> through
	 * <code>'&#92;u0037'</code>.
	 *
	 * @param   i   an integer to be converted to a string.
	 * @return  the string representation of the unsigned integer value
	 *          represented by the argument in octal (base&nbsp;8).
	 * @since   JDK1.0.2
	 */
	public static String toOctalString(int i) {
		return toUnsignedString(i, 3);
	}

	/**
	 * Returns a string representation of the integer argument as an
	 * unsigned integer in base&nbsp;2.
	 *
	 * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
	 * if the argument is negative; otherwise it is equal to the
	 * argument.  This value is converted to a string of ASCII digits
	 * in binary (base&nbsp;2) with no extra leading {@code 0}s.
	 * If the unsigned magnitude is zero, it is represented by a
	 * single zero character {@code '0'}
	 * (<code>'&#92;u0030'</code>); otherwise, the first character of
	 * the representation of the unsigned magnitude will not be the
	 * zero character. The characters {@code '0'}
	 * (<code>'&#92;u0030'</code>) and {@code '1'}
	 * (<code>'&#92;u0031'</code>) are used as binary digits.
	 *
	 * @param   i   an integer to be converted to a string.
	 * @return  the string representation of the unsigned integer value
	 *          represented by the argument in binary (base&nbsp;2).
	 * @since   JDK1.0.2
	 */
	public static String toBinaryString(int i) {
		return toUnsignedString(i, 1);
	}

	/**
	 * Convert the integer to an unsigned number.
	 */
	private static String toUnsignedString(int i, int shift) {
		char[] buf = new char[32];
		int charPos = 32;
		int radix = 1 << shift;
		int mask = radix - 1;
		do {
			buf[--charPos] = digits[i & mask];
			i >>>= shift;
		} while (i != 0);

		return new String(buf, charPos, (32 - charPos));
	}


	final static char [] DigitTens = {
			'0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
			'1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
			'2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
			'3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
			'4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
			'5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
			'6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
			'7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
			'8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
			'9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
	} ;

	final static char [] DigitOnes = {
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
	} ;

	// I use the "invariant division by multiplication" trick to
	// accelerate Integer.toString.  In particular we want to
	// avoid division by 10.
	//
	// The "trick" has roughly the same performance characteristics
	// as the "classic" Integer.toString code on a non-JIT VM.
	// The trick avoids .rem and .div calls but has a longer code
	// path and is thus dominated by dispatch overhead.  In the
	// JIT case the dispatch overhead doesn't exist and the
	// "trick" is considerably faster than the classic code.
	//
	// TODO-FIXME: convert (x * 52429) into the equiv shift-add
	// sequence.
	//
	// RE:  Division by Invariant Integers using Multiplication
	//      T Gralund, P Montgomery
	//      ACM PLDI 1994
	//

	/**
	 * Returns a {@code String} object representing the
	 * specified integer. The argument is converted to signed decimal
	 * representation and returned as a string, exactly as if the
	 * argument and radix 10 were given as arguments to the {@link
	 * #toString(int, int)} method.
	 *
	 * @param   i   an integer to be converted.
	 * @return  a string representation of the argument in base&nbsp;10.
	 */
	public static String toString(int i) {
		if (i == Integer.MIN_VALUE)
			return "-2147483648";
		int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
		char[] buf = new char[size];
		getChars(i, size, buf);
		return new String(buf, true);
	}

	/**
	 * Places characters representing the integer i into the
	 * character array buf. The characters are placed into
	 * the buffer backwards starting with the least significant
	 * digit at the specified index (exclusive), and working
	 * backwards from there.
	 *
	 * Will fail if i == Integer.MIN_VALUE
	 */
	static void getChars(int i, int index, char[] buf) {
		int q, r;
		int charPos = index;
		char sign = 0;

		if (i < 0) {
			sign = '-';
			i = -i;
		}

		// Generate two digits per iteration
		while (i >= 65536) {
			q = i / 100;
			// really: r = i - (q * 100);
			r = i - ((q << 6) + (q << 5) + (q << 2));
			i = q;
			buf [--charPos] = DigitOnes[r];
			buf [--charPos] = DigitTens[r];
		}

		// Fall thru to fast mode for smaller numbers
		// assert(i <= 65536, i);
		for (;;) {
			q = (i * 52429) >>> (16+3);
			r = i - ((q << 3) + (q << 1));  // r = i-(q*10) ...
			buf [--charPos] = digits [r];
			i = q;
			if (i == 0) break;
		}
		if (sign != 0) {
			buf [--charPos] = sign;
		}
	}

	final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
			99999999, 999999999, Integer.MAX_VALUE };

	// Requires positive x
	static int stringSize(int x) {
		for (int i=0; ; i++)
			if (x <= sizeTable[i])
				return i+1;
	}

	/**
	 * Parses the string argument as a signed integer in the radix
	 * specified by the second argument. The characters in the string
	 * must all be digits of the specified radix (as determined by
	 * whether {@link java.lang.Character#digit(char, int)} returns a
	 * nonnegative value), except that the first character may be an
	 * ASCII minus sign {@code '-'} (<code>'&#92;u002D'</code>) to
	 * indicate a negative value or an ASCII plus sign {@code '+'}
	 * (<code>'&#92;u002B'</code>) to indicate a positive value. The
	 * resulting integer value is returned.
	 *
	 * <p>An exception of type {@code NumberFormatException} is
	 * thrown if any of the following situations occurs:
	 * <ul>
	 * <li>The first argument is {@code null} or is a string of
	 * length zero.
	 *
	 * <li>The radix is either smaller than
	 * {@link java.lang.Character#MIN_RADIX} or
	 * larger than {@link java.lang.Character#MAX_RADIX}.
	 *
	 * <li>Any character of the string is not a digit of the specified
	 * radix, except that the first character may be a minus sign
	 * {@code '-'} (<code>'&#92;u002D'</code>) or plus sign
	 * {@code '+'} (<code>'&#92;u002B'</code>) provided that the
	 * string is longer than length 1.
	 *
	 * <li>The value represented by the string is not a value of type
	 * {@code int}.
	 * </ul>
	 *
	 * <p>Examples:
	 * <blockquote><pre>
	 * parseInt("0", 10) returns 0
	 * parseInt("473", 10) returns 473
	 * parseInt("+42", 10) returns 42
	 * parseInt("-0", 10) returns 0
	 * parseInt("-FF", 16) returns -255
	 * parseInt("1100110", 2) returns 102
	 * parseInt("2147483647", 10) returns 2147483647
	 * parseInt("-2147483648", 10) returns -2147483648
	 * parseInt("2147483648", 10) throws a NumberFormatException
	 * parseInt("99", 8) throws a NumberFormatException
	 * parseInt("Kona", 10) throws a NumberFormatException
	 * parseInt("Kona", 27) returns 411787
	 * </pre></blockquote>
	 *
	 * @param      s   the {@code String} containing the integer
	 *                  representation to be parsed
	 * @param      radix   the radix to be used while parsing {@code s}.
	 * @return     the integer represented by the string argument in the
	 *             specified radix.
	 * @exception  NumberFormatException if the {@code String}
	 *             does not contain a parsable {@code int}.
	 */
	public static int parseInt(String s, int radix)
			throws NumberFormatException
	{
        /*
         * WARNING: This method may be invoked early during VM initialization
         * before IntegerCache is initialized. Care must be taken to not use
         * the valueOf method.
         */

		if (s == null) {
			throw new NumberFormatException("null");
		}

		if (radix < Character.MIN_RADIX) {
			throw new NumberFormatException("radix " + radix +
					" less than Character.MIN_RADIX");
		}

		if (radix > Character.MAX_RADIX) {
			throw new NumberFormatException("radix " + radix +
					" greater than Character.MAX_RADIX");
		}

		int result = 0;
		boolean negative = false;
		int i = 0, len = s.length();
		int limit = -Integer.MAX_VALUE;
		int multmin;
		int digit;

		if (len > 0) {
			char firstChar = s.charAt(0);
			if (firstChar < '0') { // Possible leading "+" or "-"
				if (firstChar == '-') {
					negative = true;
					limit = Integer.MIN_VALUE;
				} else if (firstChar != '+')
					throw NumberFormatException.forInputString(s);

				if (len == 1) // Cannot have lone "+" or "-"
					throw NumberFormatException.forInputString(s);
				i++;
			}
			multmin = limit / radix;
			while (i < len) {
				// Accumulating negatively avoids surprises near MAX_VALUE
				digit = Character.digit(s.charAt(i++),radix);
				if (digit < 0) {
					throw NumberFormatException.forInputString(s);
				}
				if (result < multmin) {
					throw NumberFormatException.forInputString(s);
				}
				result *= radix;
				if (result < limit + digit) {
					throw NumberFormatException.forInputString(s);
				}
				result -= digit;
			}
		} else {
			throw NumberFormatException.forInputString(s);
		}
		return negative ? result : -result;
	}

	/**
	 * Parses the string argument as a signed decimal integer. The
	 * characters in the string must all be decimal digits, except
	 * that the first character may be an ASCII minus sign {@code '-'}
	 * (<code>'&#92;u002D'</code>) to indicate a negative value or an
	 * ASCII plus sign {@code '+'} (<code>'&#92;u002B'</code>) to
	 * indicate a positive value. The resulting integer value is
	 * returned, exactly as if the argument and the radix 10 were
	 * given as arguments to the {@link #parseInt(java.lang.String,
	 * int)} method.
	 *
	 * @param s    a {@code String} containing the {@code int}
	 *             representation to be parsed
	 * @return     the integer value represented by the argument in decimal.
	 * @exception  NumberFormatException  if the string does not contain a
	 *               parsable integer.
	 */
	public static int parseInt(String s) throws NumberFormatException {
		return parseInt(s,10);
	}

	/**
	 * Returns an {@code Integer} object holding the value
	 * extracted from the specified {@code String} when parsed
	 * with the radix given by the second argument. The first argument
	 * is interpreted as representing a signed integer in the radix
	 * specified by the second argument, exactly as if the arguments
	 * were given to the {@link #parseInt(java.lang.String, int)}
	 * method. The result is an {@code Integer} object that
	 * represents the integer value specified by the string.
	 *
	 * <p>In other words, this method returns an {@code Integer}
	 * object equal to the value of:
	 *
	 * <blockquote>
	 *  {@code new Integer(Integer.parseInt(s, radix))}
	 * </blockquote>
	 *
	 * @param      s   the string to be parsed.
	 * @param      radix the radix to be used in interpreting {@code s}
	 * @return     an {@code Integer} object holding the value
	 *             represented by the string argument in the specified
	 *             radix.
	 * @exception NumberFormatException if the {@code String}
	 *            does not contain a parsable {@code int}.
	 */
	public static Integer valueOf(String s, int radix) throws NumberFormatException {
		return Integer.valueOf(parseInt(s,radix));
	}

	/**
	 * Returns an {@code Integer} object holding the
	 * value of the specified {@code String}. The argument is
	 * interpreted as representing a signed decimal integer, exactly
	 * as if the argument were given to the {@link
	 * #parseInt(java.lang.String)} method. The result is an
	 * {@code Integer} object that represents the integer value
	 * specified by the string.
	 *
	 * <p>In other words, this method returns an {@code Integer}
	 * object equal to the value of:
	 *
	 * <blockquote>
	 *  {@code new Integer(Integer.parseInt(s))}
	 * </blockquote>
	 *
	 * @param      s   the string to be parsed.
	 * @return     an {@code Integer} object holding the value
	 *             represented by the string argument.
	 * @exception  NumberFormatException  if the string cannot be parsed
	 *             as an integer.
	 */
	public static Integer valueOf(String s) throws NumberFormatException {
		return Integer.valueOf(parseInt(s, 10));
	}

	/* NANITE: Removing cache to save memory */
	/**
	 * Cache to support the object identity semantics of autoboxing for values between
	 * -128 and 127 (inclusive) as required by JLS.
	 *
	 * The cache is initialized on first usage.  The size of the cache
	 * may be controlled by the -XX:AutoBoxCacheMax=<size> option.
	 * During VM initialization, java.lang.Integer.IntegerCache.high property
	 * may be set and saved in the private system properties in the
	 * sun.misc.VM class.
	 */
	/*
	private static class IntegerCache {
		static final int low = -128;
		static final int high;
		static final Integer cache[];

		static {
			// high value may be configured by property
			int h = 127;
			String integerCacheHighPropValue =
					sun.misc.VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
			if (integerCacheHighPropValue != null) {
				int i = parseInt(integerCacheHighPropValue);
				i = Math.max(i, 127);
				// Maximum array size is Integer.MAX_VALUE
				h = Math.min(i, Integer.MAX_VALUE - (-low) -1);
			}
			high = h;

			cache = new Integer[(high - low) + 1];
			int j = low;
			for(int k = 0; k < cache.length; k++)
				cache[k] = new Integer(j++);
		}

		private IntegerCache() {}
	} */

	/**
	 * Returns an {@code Integer} instance representing the specified
	 * {@code int} value.  If a new {@code Integer} instance is not
	 * required, this method should generally be used in preference to
	 * the constructor {@link #Integer(int)}, as this method is likely
	 * to yield significantly better space and time performance by
	 * caching frequently requested values.
	 *
	 * This method will always cache values in the range -128 to 127,
	 * inclusive, and may cache other values outside of this range.
	 *
	 * @param  i an {@code int} value.
	 * @return an {@code Integer} instance representing {@code i}.
	 * @since  1.5
	 */
	public static Integer valueOf(int i) {

		/* NANITE: Removing cache to save memory */
		// assert IntegerCache.high >= 127;
		//if (i >= IntegerCache.low && i <= IntegerCache.high)
		//	return IntegerCache.cache[i + (-IntegerCache.low)];
		return new Integer(i);
	}

	/**
	 * The value of the {@code Integer}.
	 *
	 * @serial
	 */
	private final int value;

	/**
	 * Constructs a newly allocated {@code Integer} object that
	 * represents the specified {@code int} value.
	 *
	 * @param   value   the value to be represented by the
	 *                  {@code Integer} object.
	 */
	public Integer(int value) {
		this.value = value;
	}

	/**
	 * Constructs a newly allocated {@code Integer} object that
	 * represents the {@code int} value indicated by the
	 * {@code String} parameter. The string is converted to an
	 * {@code int} value in exactly the manner used by the
	 * {@code parseInt} method for radix 10.
	 *
	 * @param      s   the {@code String} to be converted to an
	 *                 {@code Integer}.
	 * @exception  NumberFormatException  if the {@code String} does not
	 *               contain a parsable integer.
	 * @see        java.lang.Integer#parseInt(java.lang.String, int)
	 */
	public Integer(String s) throws NumberFormatException {
		this.value = parseInt(s, 10);
	}

	/**
	 * Returns the value of this {@code Integer} as a {@code byte}
	 * after a narrowing primitive conversion.
	 * jls 5.1.3 Narrowing Primitive Conversions
	 */
	public byte byteValue() {
		return (byte)value;
	}

	/**
	 * Returns the value of this {@code Integer} as a {@code short}
	 * after a narrowing primitive conversion.
	 * jls 5.1.3 Narrowing Primitive Conversions
	 */
	public short shortValue() {
		return (short)value;
	}

	/**
	 * Returns the value of this {@code Integer} as an
	 * {@code int}.
	 */
	public int intValue() {
		return value;
	}

	/**
	 * Returns the value of this {@code Integer} as a {@code long}
	 * after a widening primitive conversion.
	 * jls 5.1.2 Widening Primitive Conversions
	 */
	public long longValue() {
		return (long)value;
	}

	/**
	 * Returns the value of this {@code Integer} as a {@code float}
	 * after a widening primitive conversion.
	 * jls 5.1.2 Widening Primitive Conversions
	 */
	public float floatValue() {
		return (float)value;
	}

	/**
	 * Returns the value of this {@code Integer} as a {@code double}
	 * after a widening primitive conversion.
	 * jls 5.1.2 Widening Primitive Conversions
	 */
	public double doubleValue() {
		return (double)value;
	}

	/**
	 * Returns a {@code String} object representing this
	 * {@code Integer}'s value. The value is converted to signed
	 * decimal representation and returned as a string, exactly as if
	 * the integer value were given as an argument to the {@link
	 * java.lang.Integer#toString(int)} method.
	 *
	 * @return  a string representation of the value of this object in
	 *          base&nbsp;10.
	 */
	public String toString() {
		return toString(value);
	}

	/**
	 * Returns a hash code for this {@code Integer}.
	 *
	 * @return  a hash code value for this object, equal to the
	 *          primitive {@code int} value represented by this
	 *          {@code Integer} object.
	 */
	public int hashCode() {
		return value;
	}

	/**
	 * Compares this object to the specified object.  The result is
	 * {@code true} if and only if the argument is not
	 * {@code null} and is an {@code Integer} object that
	 * contains the same {@code int} value as this object.
	 *
	 * @param   obj   the object to compare with.
	 * @return  {@code true} if the objects are the same;
	 *          {@code false} otherwise.
	 */
	public boolean equals(Object obj) {
		if (obj instanceof Integer) {
			return value == ((Integer)obj).intValue();
		}
		return false;
	}

	/**
	 * Determines the integer value of the system property with the
	 * specified name.
	 *
	 * <p>The first argument is treated as the name of a system property.
	 * System properties are accessible through the
	 * {@link java.lang.System#getProperty(java.lang.String)} method. The
	 * string value of this property is then interpreted as an integer
	 * value and an {@code Integer} object representing this value is
	 * returned. Details of possible numeric formats can be found with
	 * the definition of {@code getProperty}.
	 *
	 * <p>If there is no property with the specified name, if the specified name
	 * is empty or {@code null}, or if the property does not have
	 * the correct numeric format, then {@code null} is returned.
	 *
	 * <p>In other words, this method returns an {@code Integer}
	 * object equal to the value of:
	 *
	 * <blockquote>
	 *  {@code getInteger(nm, null)}
	 * </blockquote>
	 *
	 * @param   nm   property name.
	 * @return  the {@code Integer} value of the property.
	 * @see     java.lang.System#getProperty(java.lang.String)
	 * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
	 */
	public static Integer getInteger(String nm) {
		return getInteger(nm, null);
	}

	/**
	 * Determines the integer value of the system property with the
	 * specified name.
	 *
	 * <p>The first argument is treated as the name of a system property.
	 * System properties are accessible through the {@link
	 * java.lang.System#getProperty(java.lang.String)} method. The
	 * string value of this property is then interpreted as an integer
	 * value and an {@code Integer} object representing this value is
	 * returned. Details of possible numeric formats can be found with
	 * the definition of {@code getProperty}.
	 *
	 * <p>The second argument is the default value. An {@code Integer} object
	 * that represents the value of the second argument is returned if there
	 * is no property of the specified name, if the property does not have
	 * the correct numeric format, or if the specified name is empty or
	 * {@code null}.
	 *
	 * <p>In other words, this method returns an {@code Integer} object
	 * equal to the value of:
	 *
	 * <blockquote>
	 *  {@code getInteger(nm, new Integer(val))}
	 * </blockquote>
	 *
	 * but in practice it may be implemented in a manner such as:
	 *
	 * <blockquote><pre>
	 * Integer result = getInteger(nm, null);
	 * return (result == null) ? new Integer(val) : result;
	 * </pre></blockquote>
	 *
	 * to avoid the unnecessary allocation of an {@code Integer}
	 * object when the default value is not needed.
	 *
	 * @param   nm   property name.
	 * @param   val   default value.
	 * @return  the {@code Integer} value of the property.
	 * @see     java.lang.System#getProperty(java.lang.String)
	 * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
	 */
	public static Integer getInteger(String nm, int val) {
		Integer result = getInteger(nm, null);
		return (result == null) ? Integer.valueOf(val) : result;
	}

	/**
	 * Returns the integer value of the system property with the
	 * specified name.  The first argument is treated as the name of a
	 * system property.  System properties are accessible through the
	 * {@link java.lang.System#getProperty(java.lang.String)} method.
	 * The string value of this property is then interpreted as an
	 * integer value, as per the {@code Integer.decode} method,
	 * and an {@code Integer} object representing this value is
	 * returned.
	 *
	 * <ul><li>If the property value begins with the two ASCII characters
	 *         {@code 0x} or the ASCII character {@code #}, not
	 *      followed by a minus sign, then the rest of it is parsed as a
	 *      hexadecimal integer exactly as by the method
	 *      {@link #valueOf(java.lang.String, int)} with radix 16.
	 * <li>If the property value begins with the ASCII character
	 *     {@code 0} followed by another character, it is parsed as an
	 *     octal integer exactly as by the method
	 *     {@link #valueOf(java.lang.String, int)} with radix 8.
	 * <li>Otherwise, the property value is parsed as a decimal integer
	 * exactly as by the method {@link #valueOf(java.lang.String, int)}
	 * with radix 10.
	 * </ul>
	 *
	 * <p>The second argument is the default value. The default value is
	 * returned if there is no property of the specified name, if the
	 * property does not have the correct numeric format, or if the
	 * specified name is empty or {@code null}.
	 *
	 * @param   nm   property name.
	 * @param   val   default value.
	 * @return  the {@code Integer} value of the property.
	 * @see     java.lang.System#getProperty(java.lang.String)
	 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
	 * @see java.lang.Integer#decode
	 */
	public static Integer getInteger(String nm, Integer val) {
		String v = null;
		try {
			v = System.getProperty(nm);
		} catch (IllegalArgumentException e) {
		} catch (NullPointerException e) {
		}
		if (v != null) {
			try {
				return Integer.decode(v);
			} catch (NumberFormatException e) {
			}
		}
		return val;
	}

	/**
	 * Decodes a {@code String} into an {@code Integer}.
	 * Accepts decimal, hexadecimal, and octal numbers given
	 * by the following grammar:
	 *
	 * <blockquote>
	 * <dl>
	 * <dt><i>DecodableString:</i>
	 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
	 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
	 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
	 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
	 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
	 * <p>
	 * <dt><i>Sign:</i>
	 * <dd>{@code -}
	 * <dd>{@code +}
	 * </dl>
	 * </blockquote>
	 *
	 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
	 * are as defined in section 3.10.1 of
	 * <cite>The Java&trade; Language Specification</cite>,
	 * except that underscores are not accepted between digits.
	 *
	 * <p>The sequence of characters following an optional
	 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
	 * "{@code #}", or leading zero) is parsed as by the {@code
	 * Integer.parseInt} method with the indicated radix (10, 16, or
	 * 8).  This sequence of characters must represent a positive
	 * value or a {@link NumberFormatException} will be thrown.  The
	 * result is negated if first character of the specified {@code
	 * String} is the minus sign.  No whitespace characters are
	 * permitted in the {@code String}.
	 *
	 * @param     nm the {@code String} to decode.
	 * @return    an {@code Integer} object holding the {@code int}
	 *             value represented by {@code nm}
	 * @exception NumberFormatException  if the {@code String} does not
	 *            contain a parsable integer.
	 * @see java.lang.Integer#parseInt(java.lang.String, int)
	 */
	public static Integer decode(String nm) throws NumberFormatException {
		int radix = 10;
		int index = 0;
		boolean negative = false;
		Integer result;

		if (nm.length() == 0)
			throw new NumberFormatException("Zero length string");
		char firstChar = nm.charAt(0);
		// Handle sign, if present
		if (firstChar == '-') {
			negative = true;
			index++;
		} else if (firstChar == '+')
			index++;

		// Handle radix specifier, if present
		if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
			index += 2;
			radix = 16;
		}
		else if (nm.startsWith("#", index)) {
			index ++;
			radix = 16;
		}
		else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
			index ++;
			radix = 8;
		}

		if (nm.startsWith("-", index) || nm.startsWith("+", index))
			throw new NumberFormatException("Sign character in wrong position");

		try {
			result = Integer.valueOf(nm.substring(index), radix);
			result = negative ? Integer.valueOf(-result.intValue()) : result;
		} catch (NumberFormatException e) {
			// If number is Integer.MIN_VALUE, we'll end up here. The next line
			// handles this case, and causes any genuine format error to be
			// rethrown.
			String constant = negative ? ("-" + nm.substring(index))
					: nm.substring(index);
			result = Integer.valueOf(constant, radix);
		}
		return result;
	}

	/**
	 * Compares two {@code Integer} objects numerically.
	 *
	 * @param   anotherInteger   the {@code Integer} to be compared.
	 * @return  the value {@code 0} if this {@code Integer} is
	 *          equal to the argument {@code Integer}; a value less than
	 *          {@code 0} if this {@code Integer} is numerically less
	 *          than the argument {@code Integer}; and a value greater
	 *          than {@code 0} if this {@code Integer} is numerically
	 *           greater than the argument {@code Integer} (signed
	 *           comparison).
	 * @since   1.2
	 */
	public int compareTo(Integer anotherInteger) {
		return compare(this.value, anotherInteger.value);
	}

	/**
	 * Compares two {@code int} values numerically.
	 * The value returned is identical to what would be returned by:
	 * <pre>
	 *    Integer.valueOf(x).compareTo(Integer.valueOf(y))
	 * </pre>
	 *
	 * @param  x the first {@code int} to compare
	 * @param  y the second {@code int} to compare
	 * @return the value {@code 0} if {@code x == y};
	 *         a value less than {@code 0} if {@code x < y}; and
	 *         a value greater than {@code 0} if {@code x > y}
	 * @since 1.7
	 */
	public static int compare(int x, int y) {
		return (x < y) ? -1 : ((x == y) ? 0 : 1);
	}


	// Bit twiddling

	/**
	 * The number of bits used to represent an {@code int} value in two's
	 * complement binary form.
	 *
	 * @since 1.5
	 */
	public static final int SIZE = 32;

	/**
	 * Returns an {@code int} value with at most a single one-bit, in the
	 * position of the highest-order ("leftmost") one-bit in the specified
	 * {@code int} value.  Returns zero if the specified value has no
	 * one-bits in its two's complement binary representation, that is, if it
	 * is equal to zero.
	 *
	 * @return an {@code int} value with a single one-bit, in the position
	 *     of the highest-order one-bit in the specified value, or zero if
	 *     the specified value is itself equal to zero.
	 * @since 1.5
	 */
	public static int highestOneBit(int i) {
		// HD, Figure 3-1
		i |= (i >>  1);
		i |= (i >>  2);
		i |= (i >>  4);
		i |= (i >>  8);
		i |= (i >> 16);
		return i - (i >>> 1);
	}

	/**
	 * Returns an {@code int} value with at most a single one-bit, in the
	 * position of the lowest-order ("rightmost") one-bit in the specified
	 * {@code int} value.  Returns zero if the specified value has no
	 * one-bits in its two's complement binary representation, that is, if it
	 * is equal to zero.
	 *
	 * @return an {@code int} value with a single one-bit, in the position
	 *     of the lowest-order one-bit in the specified value, or zero if
	 *     the specified value is itself equal to zero.
	 * @since 1.5
	 */
	public static int lowestOneBit(int i) {
		// HD, Section 2-1
		return i & -i;
	}

	/**
	 * Returns the number of zero bits preceding the highest-order
	 * ("leftmost") one-bit in the two's complement binary representation
	 * of the specified {@code int} value.  Returns 32 if the
	 * specified value has no one-bits in its two's complement representation,
	 * in other words if it is equal to zero.
	 *
	 * <p>Note that this method is closely related to the logarithm base 2.
	 * For all positive {@code int} values x:
	 * <ul>
	 * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
	 * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
	 * </ul>
	 *
	 * @return the number of zero bits preceding the highest-order
	 *     ("leftmost") one-bit in the two's complement binary representation
	 *     of the specified {@code int} value, or 32 if the value
	 *     is equal to zero.
	 * @since 1.5
	 */
	public static int numberOfLeadingZeros(int i) {
		// HD, Figure 5-6
		if (i == 0)
			return 32;
		int n = 1;
		if (i >>> 16 == 0) { n += 16; i <<= 16; }
		if (i >>> 24 == 0) { n +=  8; i <<=  8; }
		if (i >>> 28 == 0) { n +=  4; i <<=  4; }
		if (i >>> 30 == 0) { n +=  2; i <<=  2; }
		n -= i >>> 31;
		return n;
	}

	/**
	 * Returns the number of zero bits following the lowest-order ("rightmost")
	 * one-bit in the two's complement binary representation of the specified
	 * {@code int} value.  Returns 32 if the specified value has no
	 * one-bits in its two's complement representation, in other words if it is
	 * equal to zero.
	 *
	 * @return the number of zero bits following the lowest-order ("rightmost")
	 *     one-bit in the two's complement binary representation of the
	 *     specified {@code int} value, or 32 if the value is equal
	 *     to zero.
	 * @since 1.5
	 */
	public static int numberOfTrailingZeros(int i) {
		// HD, Figure 5-14
		int y;
		if (i == 0) return 32;
		int n = 31;
		y = i <<16; if (y != 0) { n = n -16; i = y; }
		y = i << 8; if (y != 0) { n = n - 8; i = y; }
		y = i << 4; if (y != 0) { n = n - 4; i = y; }
		y = i << 2; if (y != 0) { n = n - 2; i = y; }
		return n - ((i << 1) >>> 31);
	}

	/**
	 * Returns the number of one-bits in the two's complement binary
	 * representation of the specified {@code int} value.  This function is
	 * sometimes referred to as the <i>population count</i>.
	 *
	 * @return the number of one-bits in the two's complement binary
	 *     representation of the specified {@code int} value.
	 * @since 1.5
	 */
	public static int bitCount(int i) {
		// HD, Figure 5-2
		i = i - ((i >>> 1) & 0x55555555);
		i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
		i = (i + (i >>> 4)) & 0x0f0f0f0f;
		i = i + (i >>> 8);
		i = i + (i >>> 16);
		return i & 0x3f;
	}

	/**
	 * Returns the value obtained by rotating the two's complement binary
	 * representation of the specified {@code int} value left by the
	 * specified number of bits.  (Bits shifted out of the left hand, or
	 * high-order, side reenter on the right, or low-order.)
	 *
	 * <p>Note that left rotation with a negative distance is equivalent to
	 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
	 * distance)}.  Note also that rotation by any multiple of 32 is a
	 * no-op, so all but the last five bits of the rotation distance can be
	 * ignored, even if the distance is negative: {@code rotateLeft(val,
	 * distance) == rotateLeft(val, distance & 0x1F)}.
	 *
	 * @return the value obtained by rotating the two's complement binary
	 *     representation of the specified {@code int} value left by the
	 *     specified number of bits.
	 * @since 1.5
	 */
	public static int rotateLeft(int i, int distance) {
		return (i << distance) | (i >>> -distance);
	}

	/**
	 * Returns the value obtained by rotating the two's complement binary
	 * representation of the specified {@code int} value right by the
	 * specified number of bits.  (Bits shifted out of the right hand, or
	 * low-order, side reenter on the left, or high-order.)
	 *
	 * <p>Note that right rotation with a negative distance is equivalent to
	 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
	 * distance)}.  Note also that rotation by any multiple of 32 is a
	 * no-op, so all but the last five bits of the rotation distance can be
	 * ignored, even if the distance is negative: {@code rotateRight(val,
	 * distance) == rotateRight(val, distance & 0x1F)}.
	 *
	 * @return the value obtained by rotating the two's complement binary
	 *     representation of the specified {@code int} value right by the
	 *     specified number of bits.
	 * @since 1.5
	 */
	public static int rotateRight(int i, int distance) {
		return (i >>> distance) | (i << -distance);
	}

	/**
	 * Returns the value obtained by reversing the order of the bits in the
	 * two's complement binary representation of the specified {@code int}
	 * value.
	 *
	 * @return the value obtained by reversing order of the bits in the
	 *     specified {@code int} value.
	 * @since 1.5
	 */
	public static int reverse(int i) {
		// HD, Figure 7-1
		i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
		i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
		i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
		i = (i << 24) | ((i & 0xff00) << 8) |
				((i >>> 8) & 0xff00) | (i >>> 24);
		return i;
	}

	/**
	 * Returns the signum function of the specified {@code int} value.  (The
	 * return value is -1 if the specified value is negative; 0 if the
	 * specified value is zero; and 1 if the specified value is positive.)
	 *
	 * @return the signum function of the specified {@code int} value.
	 * @since 1.5
	 */
	public static int signum(int i) {
		// HD, Section 2-7
		return (i >> 31) | (-i >>> 31);
	}

	/**
	 * Returns the value obtained by reversing the order of the bytes in the
	 * two's complement representation of the specified {@code int} value.
	 *
	 * @return the value obtained by reversing the bytes in the specified
	 *     {@code int} value.
	 * @since 1.5
	 */
	public static int reverseBytes(int i) {
		return ((i >>> 24)           ) |
				((i >>   8) &   0xFF00) |
				((i <<   8) & 0xFF0000) |
				((i << 24));
	}

	/** use serialVersionUID from JDK 1.0.2 for interoperability */
	private static final long serialVersionUID = 1360826667806852920L;
}
