https://openjdk.java.net/ 
/*
 * Copyright (c) 1994, 2006, 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
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 * questions.
 */

package java.lang;


The Long class wraps a value of the primitive type 
long in an object. An object of type Long contains a single field whose type is long. 
 In addition, this class provides several methods for converting a long to a String and a String to a 
long, as well as other constants and methods useful when dealing with a long. 
Implementation note: The implementations of the "bit twiddling" methods (such as highestOneBit and numberOfTrailingZeros) are based on material from Henry S. Warren, Jr.'s Hacker's
Delight, (Addison Wesley, 2002).

Author: Lee Boynton,  Arthur van Hoff,  Josh Bloch,  Joseph D. Darcy
Since:  JDK1.0
/**
 * The {@code Long} class wraps a value of the primitive type {@code
 * long} in an object. An object of type {@code Long} contains a
 * single field whose type is {@code long}.
 *
 * <p> In addition, this class provides several methods for converting
 * a {@code long} to a {@code String} and a {@code String} to a {@code
 * long}, as well as other constants and methods useful when dealing
 * with a {@code long}.
 *
 * <p>Implementation note: The implementations of the "bit twiddling"
 * methods (such as {@link #highestOneBit(long) highestOneBit} and
 * {@link #numberOfTrailingZeros(long) 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 Long extends Number implements Comparable<Long> {
    
A constant holding the minimum value a long can have, -263.

/**
     * A constant holding the minimum value a {@code long} can
     * have, -2<sup>63</sup>.
     */
    public static final long MIN_VALUE = 0x8000000000000000L;

    
A constant holding the maximum value a long can have, 263-1.

/**
     * A constant holding the maximum value a {@code long} can
     * have, 2<sup>63</sup>-1.
     */
    public static final long MAX_VALUE = 0x7fffffffffffffffL;

    
The Class instance representing the primitive type long. 
Since:  JDK1.1
/**
     * The {@code Class} instance representing the primitive type
     * {@code long}.
     *
     * @since   JDK1.1
     */
    public static final Class<Long>     TYPE = (Class<Long>) Class.getPrimitiveClass("long");

    
Returns a string representation of the first argument in the
radix specified by the second argument.

If the radix is smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX, then the radix 10 is used instead. 
If the first argument is negative, the first element of the result is the ASCII minus sign '-' ('\u002d'). If the first argument is not
negative, no sign character appears in the result.

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 '0' ('\u0030'); otherwise, the first character of
the representation of the magnitude will not be the zero
character.  The following ASCII characters are used as digits:

 0123456789abcdefghijklmnopqrstuvwxyz 

These are '\u0030' through
'\u0039' and '\u0061' through
'\u007a'. If radix is N, then the first N of these characters
are used as radix-N digits in the order shown. Thus, the digits for hexadecimal (radix 16) are 0123456789abcdef. If uppercase letters are desired, the String.toUpperCase() method may be called on the result: 
 Long.toString(n, 16).toUpperCase() 


Params:
  • i –  a long to be converted to a string.
  • radix –   the radix to use in the string representation.
See Also:
Returns: a string representation of the argument in the specified radix.
/**
     * 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 sign {@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 Long.toString(n, 16).toUpperCase()}
     * </blockquote>
     *
     * @param   i       a {@code long} 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(long i, int radix) {
        if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
            radix = 10;
        if (radix == 10)
            return toString(i);
        char[] buf = new char[65];
        int charPos = 64;
        boolean negative = (i < 0);

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

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

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

        return new String(buf, charPos, (65 - charPos));
    }

    
Returns a string representation of the long argument as an unsigned integer in base 16. 
The unsigned long value is the argument plus 264 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 16) with no extra leading 0s. If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\u0030'); 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:

 0123456789abcdef 

These are the characters '\u0030' through
'\u0039' and  '\u0061' through
'\u0066'. If uppercase letters are desired, the String.toUpperCase() method may be called on the result: 
 Long.toHexString(n).toUpperCase() 


Params:
  • i –  a long to be converted to a string.
Returns: the string representation of the unsigned long value represented by the argument in hexadecimal (base 16).
Since:  JDK 1.0.2
/**
     * Returns a string representation of the {@code long}
     * argument as an unsigned integer in base&nbsp;16.
     *
     * <p>The unsigned {@code long} value is the argument plus
     * 2<sup>64</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 Long.toHexString(n).toUpperCase()}
     * </blockquote>
     *
     * @param   i   a {@code long} to be converted to a string.
     * @return  the string representation of the unsigned {@code long}
     *          value represented by the argument in hexadecimal
     *          (base&nbsp;16).
     * @since   JDK 1.0.2
     */
    public static String toHexString(long i) {
        return toUnsignedString(i, 4);
    }

    
Returns a string representation of the long argument as an unsigned integer in base 8. 
The unsigned long value is the argument plus 264 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 8) with no extra leading 0s. 
If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\u0030'); 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:

 01234567 

These are the characters '\u0030' through
'\u0037'.

Params:
  • i –  a long to be converted to a string.
Returns: the string representation of the unsigned long value represented by the argument in octal (base 8).
Since:  JDK 1.0.2
/**
     * Returns a string representation of the {@code long}
     * argument as an unsigned integer in base&nbsp;8.
     *
     * <p>The unsigned {@code long} value is the argument plus
     * 2<sup>64</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   a {@code long} to be converted to a string.
     * @return  the string representation of the unsigned {@code long}
     *          value represented by the argument in octal (base&nbsp;8).
     * @since   JDK 1.0.2
     */
    public static String toOctalString(long i) {
        return toUnsignedString(i, 3);
    }

    
Returns a string representation of the long argument as an unsigned integer in base 2. 
The unsigned long value is the argument plus 264 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 2) with no extra leading 0s. If the unsigned magnitude is zero, it is represented by a single zero character '0' ('\u0030'); otherwise, the first character of the representation of the unsigned magnitude will not be the zero character. The characters '0' ('\u0030') and '1' ('\u0031') are used as binary digits.

Params:
  • i –  a long to be converted to a string.
Returns: the string representation of the unsigned long value represented by the argument in binary (base 2).
Since:  JDK 1.0.2
/**
     * Returns a string representation of the {@code long}
     * argument as an unsigned integer in base&nbsp;2.
     *
     * <p>The unsigned {@code long} value is the argument plus
     * 2<sup>64</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   a {@code long} to be converted to a string.
     * @return  the string representation of the unsigned {@code long}
     *          value represented by the argument in binary (base&nbsp;2).
     * @since   JDK 1.0.2
     */
    public static String toBinaryString(long i) {
        return toUnsignedString(i, 1);
    }

    
Convert the integer to an unsigned number.

/**
     * Convert the integer to an unsigned number.
     */
    private static String toUnsignedString(long i, int shift) {
        char[] buf = new char[64];
        int charPos = 64;
        int radix = 1 << shift;
        long mask = radix - 1;
        do {
            buf[--charPos] = Integer.digits[(int)(i & mask)];
            i >>>= shift;
        } while (i != 0);
        return new String(buf, charPos, (64 - charPos));
    }

    
Returns a String object representing the specified long. The argument is converted to signed decimal representation and returned as a string, exactly as if the argument and the radix 10 were given as arguments to the toString(long, int) method. 
Params:
  • i –  a long to be converted.
Returns: a string representation of the argument in base 10.
/**
     * Returns a {@code String} object representing the specified
     * {@code long}.  The argument is converted to signed decimal
     * representation and returned as a string, exactly as if the
     * argument and the radix 10 were given as arguments to the {@link
     * #toString(long, int)} method.
     *
     * @param   i   a {@code long} to be converted.
     * @return  a string representation of the argument in base&nbsp;10.
     */
    public static String toString(long i) {
        if (i == Long.MIN_VALUE)
            return "-9223372036854775808";
        int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
        char[] buf = new char[size];
        getChars(i, size, buf);
        return new String(0, size, buf);
    }

    
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 == Long.MIN_VALUE

/**
     * 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 == Long.MIN_VALUE
     */
    static void getChars(long i, int index, char[] buf) {
        long q;
        int r;
        int charPos = index;
        char sign = 0;

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

        // Get 2 digits/iteration using longs until quotient fits into an int
        while (i > Integer.MAX_VALUE) {
            q = i / 100;
            // really: r = i - (q * 100);
            r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
            i = q;
            buf[--charPos] = Integer.DigitOnes[r];
            buf[--charPos] = Integer.DigitTens[r];
        }

        // Get 2 digits/iteration using ints
        int q2;
        int i2 = (int)i;
        while (i2 >= 65536) {
            q2 = i2 / 100;
            // really: r = i2 - (q * 100);
            r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
            i2 = q2;
            buf[--charPos] = Integer.DigitOnes[r];
            buf[--charPos] = Integer.DigitTens[r];
        }

        // Fall thru to fast mode for smaller numbers
        // assert(i2 <= 65536, i2);
        for (;;) {
            q2 = (i2 * 52429) >>> (16+3);
            r = i2 - ((q2 << 3) + (q2 << 1));  // r = i2-(q2*10) ...
            buf[--charPos] = Integer.digits[r];
            i2 = q2;
            if (i2 == 0) break;
        }
        if (sign != 0) {
            buf[--charPos] = sign;
        }
    }

    // Requires positive x
    static int stringSize(long x) {
        long p = 10;
        for (int i=1; i<19; i++) {
            if (x < p)
                return i;
            p = 10*p;
        }
        return 19;
    }

    
Parses the string argument as a signed long 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 Character.digit(char, int) returns a nonnegative value), except that the first character may be an ASCII minus sign '-' ('\u002D') to indicate a negative value. The resulting long value is returned. 
Note that neither the character L ('\u004C') nor l ('\u006C') is permitted to appear at the end of the string as a type indicator, as would be permitted in Java programming language source code - except that either L or l may appear as a digit for a radix greater than 22. 
An exception of type NumberFormatException is thrown if any of the following situations occurs: 
    

  • The first argument is null or is a string of length zero. 
  • The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX. 
  • Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign '-' ('\u002d') provided that the
string is longer than length 1.

  • The value represented by the string is not a value of type long. 


Examples:

parseLong("0", 10) returns 0L
parseLong("473", 10) returns 473L
parseLong("-0", 10) returns 0L
parseLong("-FF", 16) returns -255L
parseLong("1100110", 2) returns 102L
parseLong("99", 8) throws a NumberFormatException
parseLong("Hazelnut", 10) throws a NumberFormatException
parseLong("Hazelnut", 36) returns 1356099454469L



Params:
  • s –  the String containing the long representation to be parsed.
  • radix –  the radix to be used while parsing s.
Throws:
Returns: the long represented by the string argument in the specified radix.
/**
     * Parses the string argument as a signed {@code long} 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. The resulting {@code long} value is
     * returned.
     *
     * <p>Note that neither the character {@code L}
     * (<code>'&#92;u004C'</code>) nor {@code l}
     * (<code>'&#92;u006C'</code>) is permitted to appear at the end
     * of the string as a type indicator, as would be permitted in
     * Java programming language source code - except that either
     * {@code L} or {@code l} may appear as a digit for a
     * radix greater than 22.
     *
     * <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 {@code 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>) provided that the
     * string is longer than length 1.
     *
     * <li>The value represented by the string is not a value of type
     *      {@code long}.
     * </ul>
     *
     * <p>Examples:
     * <blockquote><pre>
     * parseLong("0", 10) returns 0L
     * parseLong("473", 10) returns 473L
     * parseLong("-0", 10) returns 0L
     * parseLong("-FF", 16) returns -255L
     * parseLong("1100110", 2) returns 102L
     * parseLong("99", 8) throws a NumberFormatException
     * parseLong("Hazelnut", 10) throws a NumberFormatException
     * parseLong("Hazelnut", 36) returns 1356099454469L
     * </pre></blockquote>
     *
     * @param      s       the {@code String} containing the
     *                     {@code long} representation to be parsed.
     * @param      radix   the radix to be used while parsing {@code s}.
     * @return     the {@code long} represented by the string argument in
     *             the specified radix.
     * @throws     NumberFormatException  if the string does not contain a
     *             parsable {@code long}.
     */
    public static long parseLong(String s, int radix)
              throws NumberFormatException
    {
        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");
        }

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

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

                if (len == 1) // Cannot have lone "-"
                    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 long. The characters in the string must all be decimal digits, except that the first character may be an ASCII minus sign '-' (\u002D') to indicate a negative value. The resulting long value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseLong(String, int) method. 
Note that neither the character L ('\u004C') nor l ('\u006C') is permitted to appear at the end
of the string as a type indicator, as would be permitted in
Java programming language source code.

Params:
  • s –  a String containing the long representation to be parsed
Throws:
Returns: the long represented by the argument in decimal.
/**
     * Parses the string argument as a signed decimal {@code long}.
     * 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.  The
     * resulting {@code long} value is returned, exactly as if the
     * argument and the radix {@code 10} were given as arguments to
     * the {@link #parseLong(java.lang.String, int)} method.
     *
     * <p>Note that neither the character {@code L}
     * (<code>'&#92;u004C'</code>) nor {@code l}
     * (<code>'&#92;u006C'</code>) is permitted to appear at the end
     * of the string as a type indicator, as would be permitted in
     * Java programming language source code.
     *
     * @param      s   a {@code String} containing the {@code long}
     *             representation to be parsed
     * @return     the {@code long} represented by the argument in
     *             decimal.
     * @throws     NumberFormatException  if the string does not contain a
     *             parsable {@code long}.
     */
    public static long parseLong(String s) throws NumberFormatException {
        return parseLong(s, 10);
    }

    
Returns a Long object holding the value extracted from the specified String when parsed with the radix given by the second argument. The first argument is interpreted as representing a signed long in the radix specified by the second argument, exactly as if the arguments were given to the parseLong(String, int) method. The result is a Long object that represents the long value specified by the string. 
In other words, this method returns a Long object equal to the value of: 
 new Long(Long.parseLong(s, radix)) 


Params:
  • s –       the string to be parsed
  • radix –  the radix to be used in interpreting s
Throws:
Returns: a Long object holding the value represented by the string argument in the specified radix.
/**
     * Returns a {@code Long} 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
     * {@code long} in the radix specified by the second
     * argument, exactly as if the arguments were given to the {@link
     * #parseLong(java.lang.String, int)} method. The result is a
     * {@code Long} object that represents the {@code long}
     * value specified by the string.
     *
     * <p>In other words, this method returns a {@code Long} object equal
     * to the value of:
     *
     * <blockquote>
     *  {@code new Long(Long.parseLong(s, radix))}
     * </blockquote>
     *
     * @param      s       the string to be parsed
     * @param      radix   the radix to be used in interpreting {@code s}
     * @return     a {@code Long} object holding the value
     *             represented by the string argument in the specified
     *             radix.
     * @throws     NumberFormatException  If the {@code String} does not
     *             contain a parsable {@code long}.
     */
    public static Long valueOf(String s, int radix) throws NumberFormatException {
        return new Long(parseLong(s, radix));
    }

    
Returns a Long object holding the value of the specified String. The argument is interpreted as representing a signed decimal long, exactly as if the argument were given to the parseLong(String) method. The result is a Long object that represents the integer value specified by the string. 
In other words, this method returns a Long object equal to the value of: 
 new Long(Long.parseLong(s)) 


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

    private static class LongCache {
        private LongCache(){}

        static final Long cache[] = new Long[-(-128) + 127 + 1];

        static {
            for(int i = 0; i < cache.length; i++)
                cache[i] = new Long(i - 128);
        }
    }

    
Returns a Long instance representing the specified long value. If a new Long instance is not required, this method should generally be used in preference to the constructor Long(long), as this method is likely to yield significantly better space and time performance by caching frequently requested values. 
Params:
  • l – a long value.
Returns:a Long instance representing l.
Since: 1.5
/**
     * Returns a {@code Long} instance representing the specified
     * {@code long} value.
     * If a new {@code Long} instance is not required, this method
     * should generally be used in preference to the constructor
     * {@link #Long(long)}, as this method is likely to yield
     * significantly better space and time performance by caching
     * frequently requested values.
     *
     * @param  l a long value.
     * @return a {@code Long} instance representing {@code l}.
     * @since  1.5
     */
    public static Long valueOf(long l) {
        final int offset = 128;
        if (l >= -128 && l <= 127) { // will cache
            return LongCache.cache[(int)l + offset];
        }
        return new Long(l);
    }

    
Decodes a String into a Long. Accepts decimal, hexadecimal, and octal numbers given by the following grammar: 




DecodableString:

Signopt DecimalNumeral

Signopt 0x HexDigits

Signopt 0X HexDigits

Signopt # HexDigits

Signopt 0 OctalDigits



Sign:

- 



DecimalNumeral, HexDigits, and OctalDigits
are defined in §3.10.1
of the Java
Language Specification.

The sequence of characters following an (optional) negative sign and/or radix specifier ("0x", "0X", "#", or leading zero) is parsed as by the 
Long.parseLong method with the indicated radix (10, 16, or 8). This sequence of characters must represent a positive value or a NumberFormatException will be thrown. The result is negated if first character of the specified String is the minus sign. No whitespace characters are permitted in the String. 
Params:
  • nm – the String to decode.
Throws:
See Also:
Returns: a Long object holding the long value represented by nm
Since:1.2
/**
     * Decodes a {@code String} into a {@code Long}.
     * 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 -}
     * </dl>
     * </blockquote>
     *
     * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
     * are defined in <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">&sect;3.10.1</a>
     * of the <a href="http://java.sun.com/docs/books/jls/html/">Java
     * Language Specification</a>.
     *
     * <p>The sequence of characters following an (optional) negative
     * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
     * "{@code #}", or leading zero) is parsed as by the {@code
     * Long.parseLong} 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    a {@code Long} object holding the {@code long}
     *            value represented by {@code nm}
     * @throws    NumberFormatException  if the {@code String} does not
     *            contain a parsable {@code long}.
     * @see java.lang.Long#parseLong(String, int)
     * @since 1.2
     */
    public static Long decode(String nm) throws NumberFormatException {
        int radix = 10;
        int index = 0;
        boolean negative = false;
        Long 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++;
        }

        // 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))
            throw new NumberFormatException("Sign character in wrong position");

        try {
            result = Long.valueOf(nm.substring(index), radix);
            result = negative ? new Long(-result.longValue()) : result;
        } catch (NumberFormatException e) {
            // If number is Long.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 = Long.valueOf(constant, radix);
        }
        return result;
    }

    
The value of the Long. 
@serial
/**
     * The value of the {@code Long}.
     *
     * @serial
     */
    private final long value;

    
Constructs a newly allocated Long object that represents the specified long argument. 
Params:
  • value –  the value to be represented by the Long object.
/**
     * Constructs a newly allocated {@code Long} object that
     * represents the specified {@code long} argument.
     *
     * @param   value   the value to be represented by the
     *          {@code Long} object.
     */
    public Long(long value) {
        this.value = value;
    }

    
Constructs a newly allocated Long object that represents the long value indicated by the String parameter. The string is converted to a long value in exactly the manner used by the parseLong method for radix 10. 
Params:
  • s –  the String to be converted to a Long.
Throws:
See Also:
/**
     * Constructs a newly allocated {@code Long} object that
     * represents the {@code long} value indicated by the
     * {@code String} parameter. The string is converted to a
     * {@code long} value in exactly the manner used by the
     * {@code parseLong} method for radix 10.
     *
     * @param      s   the {@code String} to be converted to a
     *             {@code Long}.
     * @throws     NumberFormatException  if the {@code String} does not
     *             contain a parsable {@code long}.
     * @see        java.lang.Long#parseLong(java.lang.String, int)
     */
    public Long(String s) throws NumberFormatException {
        this.value = parseLong(s, 10);
    }

    
Returns the value of this Long as a byte. 
/**
     * Returns the value of this {@code Long} as a
     * {@code byte}.
     */
    public byte byteValue() {
        return (byte)value;
    }

    
Returns the value of this Long as a short. 
/**
     * Returns the value of this {@code Long} as a
     * {@code short}.
     */
    public short shortValue() {
        return (short)value;
    }

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

    
Returns the value of this Long as a long value. 
/**
     * Returns the value of this {@code Long} as a
     * {@code long} value.
     */
    public long longValue() {
        return (long)value;
    }

    
Returns the value of this Long as a float. 
/**
     * Returns the value of this {@code Long} as a
     * {@code float}.
     */
    public float floatValue() {
        return (float)value;
    }

    
Returns the value of this Long as a double. 
/**
     * Returns the value of this {@code Long} as a
     * {@code double}.
     */
    public double doubleValue() {
        return (double)value;
    }

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

    
Returns a hash code for this Long. The result is the exclusive OR of the two halves of the primitive long value held by this Long object. That is, the hashcode is the value of the expression: 
 (int)(this.longValue()^(this.longValue()>>>32)) 


Returns: a hash code value for this object.
/**
     * Returns a hash code for this {@code Long}. The result is
     * the exclusive OR of the two halves of the primitive
     * {@code long} value held by this {@code Long}
     * object. That is, the hashcode is the value of the expression:
     *
     * <blockquote>
     *  {@code (int)(this.longValue()^(this.longValue()>>>32))}
     * </blockquote>
     *
     * @return  a hash code value for this object.
     */
    public int hashCode() {
        return (int)(value ^ (value >>> 32));
    }

    
Compares this object to the specified object. The result is true if and only if the argument is not null and is a Long object that contains the same long value as this object. 
Params:
  • obj –   the object to compare with.
Returns: true if the objects are the same; false otherwise.
/**
     * Compares this object to the specified object.  The result is
     * {@code true} if and only if the argument is not
     * {@code null} and is a {@code Long} object that
     * contains the same {@code long} 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 Long) {
            return value == ((Long)obj).longValue();
        }
        return false;
    }

    
Determines the long 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 System.getProperty(String) method. The string value of this property is then interpreted as a long value and a Long object representing this value is returned. Details of possible numeric formats can be found with the definition of getProperty. 
If there is no property with the specified name, if the specified name is empty or null, or if the property does not have the correct numeric format, then null is returned. 
In other words, this method returns a Long object equal to the value of: 
 getLong(nm, null) 


Params:
  • nm –   property name.
See Also:
Returns: the Long value of the property.
/**
     * Determines the {@code long} 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 a
     * {@code long} value and a {@code Long} 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 a {@code Long} object equal to
     * the value of:
     *
     * <blockquote>
     *  {@code getLong(nm, null)}
     * </blockquote>
     *
     * @param   nm   property name.
     * @return  the {@code Long} 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 Long getLong(String nm) {
        return getLong(nm, null);
    }

    
Determines the long 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 System.getProperty(String) method. The string value of this property is then interpreted as a long value and a Long object representing this value is returned. Details of possible numeric formats can be found with the definition of getProperty. 
The second argument is the default value. A Long 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 null. 
In other words, this method returns a Long object equal to the value of: 
 getLong(nm, new Long(val)) 

but in practice it may be implemented in a manner such as:

Long result = getLong(nm, null);
return (result == null) ? new Long(val) : result;

 to avoid the unnecessary allocation of a Long object when the default value is not needed. 
Params:
  • nm –    property name.
  • val –   default value.
See Also:
Returns: the Long value of the property.
/**
     * Determines the {@code long} 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 a
     * {@code long} value and a {@code Long} 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. A {@code Long} 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 null.
     *
     * <p>In other words, this method returns a {@code Long} object equal
     * to the value of:
     *
     * <blockquote>
     *  {@code getLong(nm, new Long(val))}
     * </blockquote>
     *
     * but in practice it may be implemented in a manner such as:
     *
     * <blockquote><pre>
     * Long result = getLong(nm, null);
     * return (result == null) ? new Long(val) : result;
     * </pre></blockquote>
     *
     * to avoid the unnecessary allocation of a {@code Long} object when
     * the default value is not needed.
     *
     * @param   nm    property name.
     * @param   val   default value.
     * @return  the {@code Long} 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 Long getLong(String nm, long val) {
        Long result = Long.getLong(nm, null);
        return (result == null) ? new Long(val) : result;
    }

    
Returns the long 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 System.getProperty(String) method. The string value of this property is then interpreted as a long value, as per the Long.decode method, and a Long object representing this value is returned. 
    

  • If the property value begins with the two ASCII characters 0x or the ASCII character #, not followed by a minus sign, then the rest of it is parsed as a hexadecimal integer exactly as for the method valueOf(String, int) with radix 16. 
  • If the property value begins with the ASCII character 0 followed by another character, it is parsed as an octal integer exactly as by the method valueOf(String, int) with radix 8. 
  • Otherwise the property value is parsed as a decimal integer exactly as by the method valueOf(String, int) with radix 10. 


Note that, in every case, neither L ('\u004C') nor l ('\u006C') is permitted to appear at the end
of the property value as a type indicator, as would be
permitted in Java programming language source code.

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 null. 
Params:
  • nm –   property name.
  • val –   default value.
See Also:
Returns: the Long value of the property.
/**
     * Returns the {@code long} 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 a {@code long} value, as per the
     * {@code Long.decode} method, and a {@code Long} 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 for 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>Note that, in every case, neither {@code L}
     * (<code>'&#92;u004C'</code>) nor {@code l}
     * (<code>'&#92;u006C'</code>) is permitted to appear at the end
     * of the property value as a type indicator, as would be
     * permitted in Java programming language source code.
     *
     * <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 Long} 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.Long#decode
     */
    public static Long getLong(String nm, Long val) {
        String v = null;
        try {
            v = System.getProperty(nm);
        } catch (IllegalArgumentException e) {
        } catch (NullPointerException e) {
        }
        if (v != null) {
            try {
                return Long.decode(v);
            } catch (NumberFormatException e) {
            }
        }
        return val;
    }

    
Compares two Long objects numerically. 
Params:
  • anotherLong –  the Long to be compared.
Returns: the value 0 if this Long is equal to the argument Long; a value less than 0 if this Long is numerically less than the argument Long; and a value greater than 0 if this Long is numerically greater than the argument Long (signed comparison).
Since:  1.2
/**
     * Compares two {@code Long} objects numerically.
     *
     * @param   anotherLong   the {@code Long} to be compared.
     * @return  the value {@code 0} if this {@code Long} is
     *          equal to the argument {@code Long}; a value less than
     *          {@code 0} if this {@code Long} is numerically less
     *          than the argument {@code Long}; and a value greater
     *          than {@code 0} if this {@code Long} is numerically
     *           greater than the argument {@code Long} (signed
     *           comparison).
     * @since   1.2
     */
    public int compareTo(Long anotherLong) {
        long thisVal = this.value;
        long anotherVal = anotherLong.value;
        return (thisVal<anotherVal ? -1 : (thisVal==anotherVal ? 0 : 1));
    }


    // Bit Twiddling

    
The number of bits used to represent a long value in two's complement binary form. 
Since:1.5
/**
     * The number of bits used to represent a {@code long} value in two's
     * complement binary form.
     *
     * @since 1.5
     */
    public static final int SIZE = 64;

    
Returns a long value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specified long 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. 
Returns:a long 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
/**
     * Returns a {@code long} value with at most a single one-bit, in the
     * position of the highest-order ("leftmost") one-bit in the specified
     * {@code long} 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 a {@code long} 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 long highestOneBit(long i) {
        // HD, Figure 3-1
        i |= (i >>  1);
        i |= (i >>  2);
        i |= (i >>  4);
        i |= (i >>  8);
        i |= (i >> 16);
        i |= (i >> 32);
        return i - (i >>> 1);
    }

    
Returns a long value with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit in the specified long 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. 
Returns:a long 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
/**
     * Returns a {@code long} value with at most a single one-bit, in the
     * position of the lowest-order ("rightmost") one-bit in the specified
     * {@code long} 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 a {@code long} 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 long lowestOneBit(long 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 long value. Returns 64 if the specified value has no one-bits in its two's complement representation, in other words if it is equal to zero. 
Note that this method is closely related to the logarithm base 2. For all positive long values x: 
    

  • floor(log2(x)) = 63 - numberOfLeadingZeros(x) 
  • ceil(log2(x)) = 64 - numberOfLeadingZeros(x - 1) 


Returns:the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified long value, or 64 if the value is equal to zero.
Since:1.5
/**
     * Returns the number of zero bits preceding the highest-order
     * ("leftmost") one-bit in the two's complement binary representation
     * of the specified {@code long} value.  Returns 64 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 long} values x:
     * <ul>
     * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
     * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - 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 long} value, or 64 if the value
     *     is equal to zero.
     * @since 1.5
     */
    public static int numberOfLeadingZeros(long i) {
        // HD, Figure 5-6
         if (i == 0)
            return 64;
        int n = 1;
        int x = (int)(i >>> 32);
        if (x == 0) { n += 32; x = (int)i; }
        if (x >>> 16 == 0) { n += 16; x <<= 16; }
        if (x >>> 24 == 0) { n +=  8; x <<=  8; }
        if (x >>> 28 == 0) { n +=  4; x <<=  4; }
        if (x >>> 30 == 0) { n +=  2; x <<=  2; }
        n -= x >>> 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 long value. Returns 64 if the specified value has no one-bits in its two's complement representation, in other words if it is equal to zero. 
Returns:the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified long value, or 64 if the value is equal to zero.
Since:1.5
/**
     * Returns the number of zero bits following the lowest-order ("rightmost")
     * one-bit in the two's complement binary representation of the specified
     * {@code long} value.  Returns 64 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 long} value, or 64 if the value is equal
     *     to zero.
     * @since 1.5
     */
    public static int numberOfTrailingZeros(long i) {
        // HD, Figure 5-14
        int x, y;
        if (i == 0) return 64;
        int n = 63;
        y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
        y = x <<16; if (y != 0) { n = n -16; x = y; }
        y = x << 8; if (y != 0) { n = n - 8; x = y; }
        y = x << 4; if (y != 0) { n = n - 4; x = y; }
        y = x << 2; if (y != 0) { n = n - 2; x = y; }
        return n - ((x << 1) >>> 31);
    }

    
Returns the number of one-bits in the two's complement binary representation of the specified long value. This function is sometimes referred to as the population count.

Returns:the number of one-bits in the two's complement binary representation of the specified long value.
Since:1.5
/**
     * Returns the number of one-bits in the two's complement binary
     * representation of the specified {@code long} 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 long} value.
     * @since 1.5
     */
     public static int bitCount(long i) {
        // HD, Figure 5-14
        i = i - ((i >>> 1) & 0x5555555555555555L);
        i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
        i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
        i = i + (i >>> 8);
        i = i + (i >>> 16);
        i = i + (i >>> 32);
        return (int)i & 0x7f;
     }

    
Returns the value obtained by rotating the two's complement binary representation of the specified long 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.) 
Note that left rotation with a negative distance is equivalent to right rotation: rotateLeft(val, -distance) == rotateRight(val,
distance). Note also that rotation by any multiple of 64 is a no-op, so all but the last six bits of the rotation distance can be ignored, even if the distance is negative: rotateLeft(val,
distance) == rotateLeft(val, distance & 0x3F). 
Returns:the value obtained by rotating the two's complement binary representation of the specified long value left by the specified number of bits.
Since:1.5
/**
     * Returns the value obtained by rotating the two's complement binary
     * representation of the specified {@code long} 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 64 is a
     * no-op, so all but the last six bits of the rotation distance can be
     * ignored, even if the distance is negative: {@code rotateLeft(val,
     * distance) == rotateLeft(val, distance & 0x3F)}.
     *
     * @return the value obtained by rotating the two's complement binary
     *     representation of the specified {@code long} value left by the
     *     specified number of bits.
     * @since 1.5
     */
    public static long rotateLeft(long i, int distance) {
        return (i << distance) | (i >>> -distance);
    }

    
Returns the value obtained by rotating the two's complement binary representation of the specified long 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.) 
Note that right rotation with a negative distance is equivalent to left rotation: rotateRight(val, -distance) == rotateLeft(val,
distance). Note also that rotation by any multiple of 64 is a no-op, so all but the last six bits of the rotation distance can be ignored, even if the distance is negative: rotateRight(val,
distance) == rotateRight(val, distance & 0x3F). 
Returns:the value obtained by rotating the two's complement binary representation of the specified long value right by the specified number of bits.
Since:1.5
/**
     * Returns the value obtained by rotating the two's complement binary
     * representation of the specified {@code long} 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 64 is a
     * no-op, so all but the last six bits of the rotation distance can be
     * ignored, even if the distance is negative: {@code rotateRight(val,
     * distance) == rotateRight(val, distance & 0x3F)}.
     *
     * @return the value obtained by rotating the two's complement binary
     *     representation of the specified {@code long} value right by the
     *     specified number of bits.
     * @since 1.5
     */
    public static long rotateRight(long 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 long value. 
Returns:the value obtained by reversing order of the bits in the specified long value.
Since:1.5
/**
     * Returns the value obtained by reversing the order of the bits in the
     * two's complement binary representation of the specified {@code long}
     * value.
     *
     * @return the value obtained by reversing order of the bits in the
     *     specified {@code long} value.
     * @since 1.5
     */
    public static long reverse(long i) {
        // HD, Figure 7-1
        i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
        i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
        i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
        i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
        i = (i << 48) | ((i & 0xffff0000L) << 16) |
            ((i >>> 16) & 0xffff0000L) | (i >>> 48);
        return i;
    }

    
Returns the signum function of the specified long 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.) 
Returns:the signum function of the specified long value.
Since:1.5
/**
     * Returns the signum function of the specified {@code long} 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 long} value.
     * @since 1.5
     */
    public static int signum(long i) {
        // HD, Section 2-7
        return (int) ((i >> 63) | (-i >>> 63));
    }

    
Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specified long value. 
Returns:the value obtained by reversing the bytes in the specified long value.
Since:1.5
/**
     * Returns the value obtained by reversing the order of the bytes in the
     * two's complement representation of the specified {@code long} value.
     *
     * @return the value obtained by reversing the bytes in the specified
     *     {@code long} value.
     * @since 1.5
     */
    public static long reverseBytes(long i) {
        i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
        return (i << 48) | ((i & 0xffff0000L) << 16) |
            ((i >>> 16) & 0xffff0000L) | (i >>> 48);
    }

    
use serialVersionUID from JDK 1.0.2 for interoperability 
/** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = 4290774380558885855L;
}