/*
* @(#)Long.java 1.79 04/05/11
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
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>.
*
* <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
* @version 1.79, 05/11/04
* @since JDK1.0
*/
public final class Long extends Number implements Comparable<Long> {
/**
* 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<Long> TYPE = (Class<Long>) 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>'\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>'\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>'\u0030'</code> through
* <code>'\u0039'</code> and <code>'\u0061'</code> through
* <code>'\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 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 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>'\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>'\u0030'</code> through
* <code>'\u0039'</code> and <code>'\u0061'</code> through
* <code>'\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 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 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 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>'\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>'\u0030'</code> through
* <code>'\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 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 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 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>'\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>'\u0030'</code>) and <code>'1'</code>
* (<code>'\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 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 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
*/
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 <code>long</code> 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> (<code>'\u002D'</code>) to
* indicate a negative value. The resulting <code>long</code>
* value is returned.
* <p>
* Note that neither the character <code>L</code>
* (<code>'\u004C'</code>) nor <code>l</code>
* (<code>'\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</code> or <code>l</code> may appear as a digit for a
* radix greater than 22.
* <p>
* An exception of type <code>NumberFormatException</code> is
* thrown if any of the following situations occurs:
* <ul>
* <li>The first argument is <code>null</code> or is a string of
* length zero.
* <li>The <code>radix</code> 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> (<code>'\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</code>.
* </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</code> containing the
* <code>long</code> representation to be parsed.
* @param radix the radix to be used while parsing <code>s</code>.
* @return the <code>long</code> represented by the string argument in
* the specified radix.
* @exception NumberFormatException if the string does not contain a
* parsable <code>long</code>.
*/
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, max = s.length();
long limit;
long multmin;
int digit;
if (max > 0) {
if (s.charAt(0) == '-') {
negative = true;
limit = Long.MIN_VALUE;
i++;
} else {
limit = -Long.MAX_VALUE;
}
multmin = limit / radix;
if (i < max) {
digit = Character.digit(s.charAt(i++),radix);
if (digit < 0) {
throw NumberFormatException.forInputString(s);
} else {
result = -digit;
}
}
while (i < max) {
// 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);
}
if (negative) {
if (i > 1) {
return result;
} else { /* Only got "-" */
throw NumberFormatException.forInputString(s);
}
} else {
return -result;
}
}
/**
* Parses the string argument as a signed decimal
* <code>long</code>. The characters in the string must all be
* decimal digits, except that the first character may be an ASCII
* minus sign <code>'-'</code> (<code>\u002D'</code>) to
* indicate a negative value. The resulting <code>long</code>
* value is returned, exactly as if the argument and the radix
* <code>10</code> were given as arguments to the {@link
* #parseLong(java.lang.String, int)} method.
* <p>
* Note that neither the character <code>L</code>
* (<code>'\u004C'</code>) nor <code>l</code>
* (<code>'\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</code> containing the <code>long</code>
* representation to be parsed
* @return the <code>long</code> represented by the argument in
* decimal.
* @exception NumberFormatException if the string does not contain a
* parsable <code>long</code>.
*/
public static long parseLong(String s) throws NumberFormatException {
return parseLong(s, 10);
}
/**
* Returns a <code>Long</code> object holding the value
* extracted from the specified <code>String</code> when parsed
* with the radix given by the second argument. The first
* argument is interpreted as representing a signed
* <code>long</code> 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</code> object that represents the <code>long</code>
* value specified by the string.
* <p>
* In other words, this method returns a <code>Long</code> object equal
* to the value of:
*
* <blockquote><code>
* new Long(Long.parseLong(s, radix))
* </code></blockquote>
*
* @param s the string to be parsed
* @param radix the radix to be used in interpreting <code>s</code>
* @return a <code>Long</code> object holding the value
* represented by the string argument in the specified
* radix.
* @exception NumberFormatException If the <code>String</code> does not
* contain a parsable <code>long</code>.
*/
public static Long valueOf(String s, int radix) throws NumberFormatException {
return new Long(parseLong(s, radix));
}
/**
* Returns a <code>Long</code> object holding the value
* of the specified <code>String</code>. The argument is
* interpreted as representing a signed decimal <code>long</code>,
* exactly as if the argument were given to the {@link
* #parseLong(java.lang.String)} method. The result is a
* <code>Long</code> object that represents the integer value
* specified by the string.
* <p>
* In other words, this method returns a <code>Long</code> object
* equal to the value of:
*
* <blockquote><pre>
* new Long(Long.parseLong(s))
* </pre></blockquote>
*
* @param s the string to be parsed.
* @return a <code>Long</code> object holding the value
* represented by the string argument.
* @exception NumberFormatException If the string cannot be parsed
* as a <code>long</code>.
*/
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 <tt>Long</tt> instance representing the specified
* <tt>long</tt> value.
* If a new <tt>Long</tt> 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 <tt>Long</tt> instance representing <tt>l</tt>.
* @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 <code>String</code> into a <code>Long</code>.
* 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</code> <i>HexDigits</i>
* <dd><i>Sign<sub>opt</sub></i> <code>0X</code> <i>HexDigits</i>
* <dd><i>Sign<sub>opt</sub></i> <code>#</code> <i>HexDigits</i>
* <dd><i>Sign<sub>opt</sub></i> <code>0</code> <i>OctalDigits</i>
* <p>
* <dt><i>Sign:</i>
* <dd><code>-</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">§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>",
* "<code>0X</code>", "<code>#</code>", or
* leading zero) is parsed as by the <code>Long.parseLong</code>
* 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</code> is the
* minus sign. No whitespace characters are permitted in the
* <code>String</code>.
*
* @param nm the <code>String</code> to decode.
* @return a <code>Long</code> object holding the <code>long</code>
* value represented by <code>nm</code>
* @exception NumberFormatException if the <code>String</code> does not
* contain a parsable <code>long</code>.
* @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;
// Handle minus sign, if present
if (nm.startsWith("-")) {
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("Negative sign in wrong position");
try {
result = Long.valueOf(nm.substring(index), radix);
result = negative ? new Long((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 ? new String("-" + nm.substring(index))
: nm.substring(index);
result = Long.valueOf(constant, radix);
}
return result;
}
/**
* The value of the <code>Long</code>.
*
* @serial
*/
private final long value;
/**
* Constructs a newly allocated <code>Long</code> object that
* represents the specified <code>long</code> argument.
*
* @param value the value to be represented by the
* <code>Long</code> object.
*/
public Long(long value) {
this.value = value;
}
/**
* Constructs a newly allocated <code>Long</code> object that
* represents the <code>long</code> value indicated by the
* <code>String</code> parameter. The string is converted to a
* <code>long</code> value in exactly the manner used by the
* <code>parseLong</code> method for radix 10.
*
* @param s the <code>String</code> to be converted to a
* <code>Long</code>.
* @exception NumberFormatException if the <code>String</code> does not
* contain a parsable <code>long</code>.
* @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 <code>Long</code> as a
* <code>byte</code>.
*/
public byte byteValue() {
return (byte)value;
}
/**
* Returns the value of this <code>Long</code> as a
* <code>short</code>.
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this <code>Long</code> as an
* <code>int</code>.
*/
public int intValue() {
return (int)value;
}
/**
* Returns the value of this <code>Long</code> as a
* <code>long</code> value.
*/
public long longValue() {
return (long)value;
}
/**
* Returns the value of this <code>Long</code> as a
* <code>float</code>.
*/
public float floatValue() {
return (float)value;
}
/**
* Returns the value of this <code>Long</code> as a
* <code>double</code>.
*/
public double doubleValue() {
return (double)value;
}
/**
* Returns a <code>String</code> object representing this
* <code>Long</code>'s value. The value is converted to signed
* decimal representation and returned as a string, exactly as if
* the <code>long</code> 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 10.
*/
public String toString() {
return String.valueOf(value);
}
/**
* Returns a hash code for this <code>Long</code>. The result is
* the exclusive OR of the two halves of the primitive
* <code>long</code> value held by this <code>Long</code>
* object. That is, the hashcode is the value of the expression:
* <blockquote><pre>
* (int)(this.longValue()^(this.longValue()>>>32))
* </pre></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
* <code>true</code> if and only if the argument is not
* <code>null</code> and is a <code>Long</code> object that
* contains the same <code>long</code> value as this object.
*
* @param obj the object to compare with.
* @return <code>true</code> if the objects are the same;
* <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof Long) {
return value == ((Long)obj).longValue();
}
return false;
}
/**
* Determines the <code>long</code> 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</code> value and a <code>Long</code> object
* representing this value is returned. Details of possible
* numeric formats can be found with the definition of
* <code>getProperty</code>.
* <p>
* If there is no property with the specified name, if the
* specified name is empty or <code>null</code>, or if the
* property does not have the correct numeric format, then
* <code>null</code> is returned.
* <p>
* In other words, this method returns a <code>Long</code> object equal to
* the value of:
* <blockquote><code>
* getLong(nm, null)
* </code></blockquote>
*
* @param nm property name.
* @return the <code>Long</code> 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 <code>long</code> 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</code> value and a <code>Long</code> object
* representing this value is returned. Details of possible
* numeric formats can be found with the definition of
* <code>getProperty</code>.
* <p>
* The second argument is the default value. A <code>Long</code> 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</code> object equal
* to the value of:
* <blockquote><code>
* getLong(nm, new Long(val))
* </code></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</code> object when
* the default value is not needed.
*
* @param nm property name.
* @param val default value.
* @return the <code>Long</code> 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 <code>long</code> 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</code> value, as per the
* <code>Long.decode</code> method, and a <code>Long</code> object
* representing this value is returned.
* <p><ul>
* <li>If the property value begins with the two ASCII characters
* <code>0x</code> or the ASCII character <code>#</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</code> 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>
* (<code>'\u004C'</code>) nor <code>l</code>
* (<code>'\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</code>.
*
* @param nm property name.
* @param val default value.
* @return the <code>Long</code> 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 <code>Long</code> objects numerically.
*
* @param anotherLong the <code>Long</code> to be compared.
* @return the value <code>0</code> if this <code>Long</code> is
* equal to the argument <code>Long</code>; a value less than
* <code>0</code> if this <code>Long</code> is numerically less
* than the argument <code>Long</code>; and a value greater
* than <code>0</code> if this <code>Long</code> is numerically
* greater than the argument <code>Long</code> (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 <tt>long</tt> value in two's
* complement binary form.
*
* @since 1.5
*/
public static final int SIZE = 64;
/**
* Returns an <tt>long</tt> value with at most a single one-bit, in the
* position of the highest-order ("leftmost") one-bit in the specified
* <tt>long</tt> 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 <tt>long</tt> 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 an <tt>long</tt> value with at most a single one-bit, in the
* position of the lowest-order ("rightmost") one-bit in the specified
* <tt>long</tt> 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 <tt>long</tt> 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 <tt>long</tt> 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 <tt>long</tt> values x:
* <ul>
* <li>floor(log<sub>2</sub>(x)) = <tt>63 - numberOfLeadingZeros(x)</tt>
* <li>ceil(log<sub>2</sub>(x)) = <tt>64 - numberOfLeadingZeros(x - 1)</tt>
* </ul>
*
* @return the number of zero bits preceding the highest-order
* ("leftmost") one-bit in the two's complement binary representation
* of the specified <tt>long</tt> 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
* <tt>long</tt> 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 <tt>long</tt> 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 <tt>long</tt> 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 <tt>long</tt> 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 <tt>long</tt> 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: <tt>rotateLeft(val, -distance) == rotateRight(val,
* distance)</tt>. 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: <tt>rotateLeft(val,
* distance) == rotateLeft(val, distance & 0x3F)</tt>.
*
* @return the value obtained by rotating the two's complement binary
* representation of the specified <tt>long</tt> 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 <tt>long</tt> 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: <tt>rotateRight(val, -distance) == rotateLeft(val,
* distance)</tt>. 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: <tt>rotateRight(val,
* distance) == rotateRight(val, distance & 0x3F)</tt>.
*
* @return the value obtained by rotating the two's complement binary
* representation of the specified <tt>long</tt> 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 <tt>long</tt>
* value.
*
* @return the value obtained by reversing order of the bits in the
* specified <tt>long</tt> 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 <tt>long</tt> 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 <tt>long</tt> 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 <tt>long</tt> value.
*
* @return the value obtained by reversing the bytes in the specified
* <tt>long</tt> 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 */
private static final long serialVersionUID = 4290774380558885855L;
}
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