long.java

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/*
 * @(#)Long.java	1.59 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program 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.   
 *   
 * This program 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 at /legal/license.txt).   
 *   
 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package java.lang;

/**
 * The <code>Long</code> class wraps a value of the primitive type
 * <code>long</code> in an object. An object of type <code>Long</code>
 * contains a single field whose type is <code>long</code>.
 *
 * <p> 
 *
 * In addition, this class provides several methods for converting a
 * <code>long</code> to a <code>String</code> and a
 * <code>String</code> to a <code>long</code>, as well as other
 * constants and methods useful when dealing with a <code>long</code>.
 *
 * @author  Lee Boynton
 * @author  Arthur van Hoff
 * @version 1.52, 02/02/00
 * @since   JDK1.0
 */
public final class Long extends Number implements Comparable {
    /**
     * A constant holding the minimum value a <code>long</code> can
     * have, -2<sup>63</sup>.
     */
    public static final long MIN_VALUE = 0x8000000000000000L;

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

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

    /**
     * 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</code>
     * or larger than <code>Character.MAX_RADIX</code>, then the radix
     * <code>10</code> is used instead.
     * <p>
     * If the first argument is negative, the first element of the
     * result is the ASCII minus sign <code>'-'</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>
     * (<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><pre>
     *   0123456789abcdefghijklmnopqrstuvwxyz
     * </pre></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</code> 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</code>. If uppercase letters are
     * desired, the {@link java.lang.String#toUpperCase()} method may
     * be called on the result:
     * <blockquote><pre>
     * Long.toString(n, 16).toUpperCase()
     * </pre></blockquote>
     * 
     * @param   i       a <code>long</code>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 <code>long</code>
     * argument as an unsigned integer in base&nbsp;16.
     * <p>
     * The unsigned <code>long</code> 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</code>s.  If the unsigned magnitude is zero, it
     * is represented by a single zero character <code>'0'</code>
     * (<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><pre>
     * 0123456789abcdef
     * </pre></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><pre>
     * Long.toHexString(n).toUpperCase()
     * </pre></blockquote>
     *
     * @param   i   a <code>long</code> to be converted to a string.
     * @return  the string representation of the unsigned <code>long</code>
     * 		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 <code>long</code>
     * argument as an unsigned integer in base&nbsp;8.
     * <p>
     * The unsigned <code>long</code> 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</code>s.
     * <p>
     * If the unsigned magnitude is zero, it is represented by a
     * single zero character <code>'0'</code>
     * (<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><pre>
     * 01234567
     * </pre></blockquote>
     * These are the characters <code>'&#92;u0030'</code> through 
     * <code>'&#92;u0037'</code>. 
     *
     * @param   i   a <code>long</code> to be converted to a string.
     * @return  the string representation of the unsigned <code>long</code> 
     *		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 <code>long</code>
     * argument as an unsigned integer in base&nbsp;2.
     * <p>
     * The unsigned <code>long</code> 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</code>s.  If the unsigned magnitude is zero, it is
     * represented by a single zero character <code>'0'</code>
     * (<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>
     * (<code>'&#92;u0030'</code>) and <code>'1'</code>
     * (<code>'&#92;u0031'</code>) are used as binary digits.
     *
     * @param   i   a <code>long</code> to be converted to a string.
     * @return  the string representation of the unsigned <code>long</code> 
     *          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.
     */
    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 <code>String</code> object representing the specified
     * <code>long</code>.  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</code> 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";
        char[] buf = (char[])(perThreadBuffer.get());
        int charPos = getChars(i, buf);
        return new String(buf, charPos, (20 - charPos));
    }

    // Per-thread buffer for string/stringbuffer conversion
    private static ThreadLocal perThreadBuffer = new ThreadLocal() {
        protected synchronized Object initialValue() {
            return new char[20];
        }
    };

    private static int getChars(long i, char[] buf) {
        long q;
        int r;
        int charPos = 20;
        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
        if (sun.misc.BuildFlags.qAssertsEnabled)
           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) {