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   /*
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    * published by the Free Software Foundation.  Sun designates this
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   * 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).
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  package java.lang;

The Integer class wraps a value of the primitive type int in an object. An object of type Integer contains a single field whose type is int.

In addition, this class provides several methods for converting an int to a String and a String to an int, as well as other constants and methods useful when dealing with an int.

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(s):
Lee Boynton
Arthur van Hoff
Josh Bloch
Joseph D. Darcy
Since:
JDK1.0
  
  public final class Integer extends Number implements Comparable<Integer> {
    
A constant holding the minimum value an int can have, -231.
  
      public static final int   MIN_VALUE = 0x80000000;

    
A constant holding the maximum value an int can have, 231-1.
  
      public static final int   MAX_VALUE = 0x7fffffff;

    
The Class instance representing the primitive type int.

Since:
JDK1.1
  
      public static final Class<Integer>  TYPE = (Class<Integer>) Class.getPrimitiveClass("int");

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

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

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 character '-' ('\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:
Integer.toString(n, 16).toUpperCase()

Parameters:
i an integer to be converted to a string.
radix the radix to use in the string representation.
Returns:
a string representation of the argument in the specified radix.
See also:
Character.MAX_RADIX
Character.MIN_RADIX
 
     public static String toString(int iint radix) {
 
         if (radix < . || radix > .)
             radix = 10;
 
         /* Use the faster version */
         if (radix == 10) {
             return toString(i);
         }
 
         char buf[] = new char[33];
         boolean negative = (i < 0);
         int charPos = 32;
 
         if (!negative) {
             i = -i;
         }
 
         while (i <= -radix) {
             buf[charPos--] = [-(i % radix)];
             i = i / radix;
         }
         buf[charPos] = [-i];
 
         if (negative) {
             buf[--charPos] = '-';
         }
 
         return new String(bufcharPos, (33 - charPos));
     }

    
Returns a string representation of the integer argument as an unsigned integer in base 16.

The unsigned integer value is the argument plus 232 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:
Integer.toHexString(n).toUpperCase()

Parameters:
i an integer to be converted to a string.
Returns:
the string representation of the unsigned integer value represented by the argument in hexadecimal (base 16).
Since:
JDK1.0.2
 
     public static String toHexString(int i) {
         return toUnsignedString(i, 4);
     }

    
Returns a string representation of the integer argument as an unsigned integer in base 8.

The unsigned integer value is the argument plus 232 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'.

Parameters:
i an integer to be converted to a string.
Returns:
the string representation of the unsigned integer value represented by the argument in octal (base 8).
Since:
JDK1.0.2
 
     public static String toOctalString(int i) {
         return toUnsignedString(i, 3);
     }

    
Returns a string representation of the integer argument as an unsigned integer in base 2.

The unsigned integer value is the argument plus 232 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.

Parameters:
i an integer to be converted to a string.
Returns:
the string representation of the unsigned integer value represented by the argument in binary (base 2).
Since:
JDK1.0.2
 
     public static String toBinaryString(int i) {
         return toUnsignedString(i, 1);
     }

    
Convert the integer to an unsigned number.
 
     private static String toUnsignedString(int iint shift) {
         char[] buf = new char[32];
         int charPos = 32;
         int radix = 1 << shift;
         int mask = radix - 1;
         do {
             buf[--charPos] = [i & mask];
             i >>>= shift;
         } while (i != 0);
 
         return new String(bufcharPos, (32 - charPos));
     }
 
 
     final static char [] DigitTens = {
         '0''0''0''0''0''0''0''0''0''0',
         '1''1''1''1''1''1''1''1''1''1',
         '2''2''2''2''2''2''2''2''2''2',
         '3''3''3''3''3''3''3''3''3''3',
         '4''4''4''4''4''4''4''4''4''4',
         '5''5''5''5''5''5''5''5''5''5',
         '6''6''6''6''6''6''6''6''6''6',
         '7''7''7''7''7''7''7''7''7''7',
         '8''8''8''8''8''8''8''8''8''8',
         '9''9''9''9''9''9''9''9''9''9',
         } ;
 
     final static char [] DigitOnes = {
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         '0''1''2''3''4''5''6''7''8''9',
         } ;
 
         // I use the "invariant division by multiplication" trick to
         // accelerate Integer.toString.  In particular we want to
         // avoid division by 10.
         //
         // The "trick" has roughly the same performance characteristics
         // as the "classic" Integer.toString code on a non-JIT VM.
         // The trick avoids .rem and .div calls but has a longer code
         // path and is thus dominated by dispatch overhead.  In the
         // JIT case the dispatch overhead doesn't exist and the
         // "trick" is considerably faster than the classic code.
         //
         // TODO-FIXME: convert (x * 52429) into the equiv shift-add
         // sequence.
         //
         // RE:  Division by Invariant Integers using Multiplication
         //      T Gralund, P Montgomery
         //      ACM PLDI 1994
         //
 
    
Returns a String object representing the specified integer. The argument is converted to signed decimal representation and returned as a string, exactly as if the argument and radix 10 were given as arguments to the toString(int,int) method.

Parameters:
i an integer to be converted.
Returns:
a string representation of the argument in base 10.
 
     public static String toString(int i) {
         if (i == .)
             return "-2147483648";
         int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
         char[] buf = new char[size];
         getChars(isizebuf);
         return new String(0, sizebuf);
     }

    
Places characters representing the integer i into the character array buf. The characters are placed into the buffer backwards starting with the least significant digit at the specified index (exclusive), and working backwards from there. Will fail if i == Integer.MIN_VALUE
 
     static void getChars(int iint indexchar[] buf) {
         int qr;
         int charPos = index;
         char sign = 0;
 
         if (i < 0) {
             sign = '-';
             i = -i;
         }
 
         // Generate two digits per iteration
         while (i >= 65536) {
             q = i / 100;
         // really: r = i - (q * 100);
             r = i - ((q << 6) + (q << 5) + (q << 2));
             i = q;
             buf [--charPos] = [r];
             buf [--charPos] = [r];
         }
 
         // Fall thru to fast mode for smaller numbers
         // assert(i <= 65536, i);
         for (;;) {
             q = (i * 52429) >>> (16+3);
             r = i - ((q << 3) + (q << 1));  // r = i-(q*10) ...
             buf [--charPos] =  [r];
             i = q;
             if (i == 0) break;
         }
         if (sign != 0) {
             buf [--charPos] = sign;
         }
     }
 
     final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
                                       99999999, 999999999, . };
 
     // Requires positive x
     static int stringSize(int x) {
         for (int i=0; ; i++)
             if (x <= [i])
                 return i+1;
     }

    
Parses the string argument as a signed integer in the radix specified by the second argument. The characters in the string must all be digits of the specified radix (as determined by whether 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 integer value is returned.

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 int.

Examples:

 parseInt("0", 10) returns 0
 parseInt("473", 10) returns 473
 parseInt("-0", 10) returns 0
 parseInt("-FF", 16) returns -255
 parseInt("1100110", 2) returns 102
 parseInt("2147483647", 10) returns 2147483647
 parseInt("-2147483648", 10) returns -2147483648
 parseInt("2147483648", 10) throws a NumberFormatException
 parseInt("99", 8) throws a NumberFormatException
 parseInt("Kona", 10) throws a NumberFormatException
 parseInt("Kona", 27) returns 411787
 

Parameters:
s the String containing the integer representation to be parsed
radix the radix to be used while parsing s.
Returns:
the integer represented by the string argument in the specified radix.
Throws:
NumberFormatException if the String does not contain a parsable int.
 
     public static int parseInt(String sint radix)
                 throws NumberFormatException
     {
         if (s == null) {
             throw new NumberFormatException("null");
         }
 
         if (radix < .) {
             throw new NumberFormatException("radix " + radix +
                                             " less than Character.MIN_RADIX");
         }
 
         if (radix > .) {
             throw new NumberFormatException("radix " + radix +
                                             " greater than Character.MAX_RADIX");
         }
 
         int result = 0;
         boolean negative = false;
         int i = 0, len = s.length();
         int limit = -.;
         int multmin;
         int digit;
 
         if (len > 0) {
             char firstChar = s.charAt(0);
             if (firstChar < '0') { // Possible leading "-"
                 if (firstChar == '-') {
                     negative = true;
                     limit = .;
                 } 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 integer. 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 integer value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseInt(java.lang.String,int) method.

Parameters:
s a String containing the int representation to be parsed
Returns:
the integer value represented by the argument in decimal.
Throws:
NumberFormatException if the string does not contain a parsable integer.
 
     public static int parseInt(String sthrows NumberFormatException {
         return parseInt(s,10);
     }

    
Returns an Integer 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 integer in the radix specified by the second argument, exactly as if the arguments were given to the parseInt(java.lang.String,int) method. The result is an Integer object that represents the integer value specified by the string.

In other words, this method returns an Integer object equal to the value of:

new Integer(Integer.parseInt(s, radix))

Parameters:
s the string to be parsed.
radix the radix to be used in interpreting s
Returns:
an Integer object holding the value represented by the string argument in the specified radix.
Throws:
NumberFormatException if the String does not contain a parsable int.
 
     public static Integer valueOf(String sint radixthrows NumberFormatException {
         return new Integer(parseInt(s,radix));
     }

    
Returns an Integer object holding the value of the specified String. The argument is interpreted as representing a signed decimal integer, exactly as if the argument were given to the parseInt(java.lang.String) method. The result is an Integer object that represents the integer value specified by the string.

In other words, this method returns an Integer object equal to the value of:

new Integer(Integer.parseInt(s))

Parameters:
s the string to be parsed.
Returns:
an Integer object holding the value represented by the string argument.
Throws:
NumberFormatException if the string cannot be parsed as an integer.
 
     public static Integer valueOf(String sthrows NumberFormatException
     {
         return new Integer(parseInt(s, 10));
     }
 
     private static class IntegerCache {
         private IntegerCache(){}
 
         static final Integer cache[] = new Integer[-(-128) + 127 + 1];
 
         static {
             for(int i = 0; i < .i++)
                 [i] = new Integer(i - 128);
         }
     }

    
Returns an Integer instance representing the specified int value. If a new Integer instance is not required, this method should generally be used in preference to the constructor Integer(int), as this method is likely to yield significantly better space and time performance by caching frequently requested values.

Parameters:
i an int value.
Returns:
an Integer instance representing i.
Since:
1.5
 
     public static Integer valueOf(int i) {
         final int offset = 128;
         if (i >= -128 && i <= 127) { // must cache
             return .[i + offset];
         }
         return new Integer(i);
     }

    
The value of the Integer.

Serial:
 
     private final int value;

    
Constructs a newly allocated Integer object that represents the specified int value.

Parameters:
value the value to be represented by the Integer object.
 
     public Integer(int value) {
         this. = value;
     }

    
Constructs a newly allocated Integer object that represents the int value indicated by the String parameter. The string is converted to an int value in exactly the manner used by the parseInt method for radix 10.

Parameters:
s the String to be converted to an Integer.
Throws:
NumberFormatException if the String does not contain a parsable integer.
See also:
parseInt(java.lang.String,int)
 
     public Integer(String sthrows NumberFormatException {
         this. = parseInt(s, 10);
     }

    
Returns the value of this Integer as a byte.
 
     public byte byteValue() {
         return (byte);
     }

    
Returns the value of this Integer as a short.
 
     public short shortValue() {
         return (short);
     }

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

    
Returns the value of this Integer as a long.
 
     public long longValue() {
         return (long);
     }

    
Returns the value of this Integer as a float.
 
     public float floatValue() {
         return (float);
     }

    
Returns the value of this Integer as a double.
 
     public double doubleValue() {
         return (double);
     }

    
Returns a String object representing this Integer's value. The value is converted to signed decimal representation and returned as a string, exactly as if the integer value were given as an argument to the toString(int) method.

Returns:
a string representation of the value of this object in base 10.
 
     public String toString() {
         return String.valueOf();
     }

    
Returns a hash code for this Integer.

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

    
Compares this object to the specified object. The result is true if and only if the argument is not null and is an Integer object that contains the same int value as this object.

Parameters:
obj the object to compare with.
Returns:
true if the objects are the same; false otherwise.
 
     public boolean equals(Object obj) {
         if (obj instanceof Integer) {
             return  == ((Integer)obj).intValue();
         }
         return false;
     }

    
Determines the integer value of the system property with the specified name.

The first argument is treated as the name of a system property. System properties are accessible through the System.getProperty(java.lang.String) method. The string value of this property is then interpreted as an integer value and an Integer 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 an Integer object equal to the value of:

getInteger(nm, null)

Parameters:
nm property name.
Returns:
the Integer value of the property.
See also:
System.getProperty(java.lang.String)
System.getProperty(java.lang.String,java.lang.String)
 
     public static Integer getInteger(String nm) {
         return getInteger(nmnull);
     }

    
Determines the integer value of the system property with the specified name.

The first argument is treated as the name of a system property. System properties are accessible through the System.getProperty(java.lang.String) method. The string value of this property is then interpreted as an integer value and an Integer 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. An Integer object that represents the value of the second argument is returned if there is no property of the specified name, if the property does not have the correct numeric format, or if the specified name is empty or null.

In other words, this method returns an Integer object equal to the value of:

getInteger(nm, new Integer(val))
but in practice it may be implemented in a manner such as:
 Integer result = getInteger(nm, null);
 return (result == null) ? new Integer(val) : result;
 
to avoid the unnecessary allocation of an Integer object when the default value is not needed.

Parameters:
nm property name.
val default value.
Returns:
the Integer value of the property.
See also:
System.getProperty(java.lang.String)
System.getProperty(java.lang.String,java.lang.String)
 
     public static Integer getInteger(String nmint val) {
         Integer result = getInteger(nmnull);
         return (result == null) ? new Integer(val) : result;
     }

    
Returns the integer value of the system property with the specified name. The first argument is treated as the name of a system property. System properties are accessible through the System.getProperty(java.lang.String) method. The string value of this property is then interpreted as an integer value, as per the Integer.decode method, and an Integer 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 by the method valueOf(java.lang.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(java.lang.String,int) with radix 8.
  • Otherwise, the property value is parsed as a decimal integer exactly as by the method valueOf(java.lang.String,int) with radix 10.

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.

Parameters:
nm property name.
val default value.
Returns:
the Integer value of the property.
See also:
System.getProperty(java.lang.String)
System.getProperty(java.lang.String,java.lang.String)
decode(java.lang.String)
 
     public static Integer getInteger(String nmInteger val) {
         String v = null;
         try {
             v = System.getProperty(nm);
         } catch (IllegalArgumentException e) {
         } catch (NullPointerException e) {
         }
         if (v != null) {
             try {
                 return Integer.decode(v);
             } catch (NumberFormatException e) {
             }
         }
         return val;
     }

    
Decodes a String into an Integer. 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 Integer.parseInt 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.

Parameters:
nm the String to decode.
Returns:
an Integer object holding the int value represented by nm
Throws:
NumberFormatException if the String does not contain a parsable integer.
See also:
parseInt(java.lang.String,int)
 
     public static Integer decode(String nmthrows NumberFormatException {
         int radix = 10;
         int index = 0;
         boolean negative = false;
         Integer result;
 
         if (nm.length() == 0)
             throw new NumberFormatException("Zero length string");
         char firstChar = nm.charAt(0);
         // Handle sign, if present
         if (firstChar == '-') {
             negative = true;
             index++;
         }
 
         // 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 = Integer.valueOf(nm.substring(index), radix);
             result = negative ? new Integer(-result.intValue()) : result;
         } catch (NumberFormatException e) {
             // If number is Integer.MIN_VALUE, we'll end up here. The next line
             // handles this case, and causes any genuine format error to be
             // rethrown.
             String constant = negative ? ("-" + nm.substring(index))
                                        : nm.substring(index);
             result = Integer.valueOf(constantradix);
         }
         return result;
     }

    
Compares two Integer objects numerically.

Parameters:
anotherInteger the Integer to be compared.
Returns:
the value 0 if this Integer is equal to the argument Integer; a value less than 0 if this Integer is numerically less than the argument Integer; and a value greater than 0 if this Integer is numerically greater than the argument Integer (signed comparison).
Since:
1.2
 
     public int compareTo(Integer anotherInteger) {
         int thisVal = this.;
         int anotherVal = anotherInteger.value;
         return (thisVal<anotherVal ? -1 : (thisVal==anotherVal ? 0 : 1));
     }
 
 
     // Bit twiddling
 
    
The number of bits used to represent an int value in two's complement binary form.

Since:
1.5
 
     public static final int SIZE = 32;

    
Returns an int value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specified int value. Returns zero if the specified value has no one-bits in its two's complement binary representation, that is, if it is equal to zero.

Returns:
an int value with a single one-bit, in the position of the highest-order one-bit in the specified value, or zero if the specified value is itself equal to zero.
Since:
1.5
 
     public static int highestOneBit(int i) {
         // HD, Figure 3-1
         i |= (i >>  1);
         i |= (i >>  2);
         i |= (i >>  4);
         i |= (i >>  8);
         i |= (i >> 16);
         return i - (i >>> 1);
     }

    
Returns an int value with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit in the specified int value. Returns zero if the specified value has no one-bits in its two's complement binary representation, that is, if it is equal to zero.

Returns:
an int value with a single one-bit, in the position of the lowest-order one-bit in the specified value, or zero if the specified value is itself equal to zero.
Since:
1.5
    public static int lowestOneBit(int i) {
        // HD, Section 2-1
        return i & -i;
    }

    
Returns the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified int value. Returns 32 if the specified value has no one-bits in its two's complement representation, in other words if it is equal to zero.

Note that this method is closely related to the logarithm base 2. For all positive int values x:

  • floor(log2(x)) = 31 - numberOfLeadingZeros(x)
  • ceil(log2(x)) = 32 - 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 int value, or 32 if the value is equal to zero.
Since:
1.5
    public static int numberOfLeadingZeros(int i) {
        // HD, Figure 5-6
        if (i == 0)
            return 32;
        int n = 1;
        if (i >>> 16 == 0) { n += 16; i <<= 16; }
        if (i >>> 24 == 0) { n +=  8; i <<=  8; }
        if (i >>> 28 == 0) { n +=  4; i <<=  4; }
        if (i >>> 30 == 0) { n +=  2; i <<=  2; }
        n -= i >>> 31;
        return n;
    }

    
Returns the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified int value. Returns 32 if the specified value has no one-bits in its two's complement representation, in other words if it is equal to zero.

Returns:
the number of zero bits following the lowest-order ("rightmost") one-bit in the two's complement binary representation of the specified int value, or 32 if the value is equal to zero.
Since:
1.5
    public static int numberOfTrailingZeros(int i) {
        // HD, Figure 5-14
        int y;
        if (i == 0) return 32;
        int n = 31;
        y = i <<16; if (y != 0) { n = n -16; i = y; }
        y = i << 8; if (y != 0) { n = n - 8; i = y; }
        y = i << 4; if (y != 0) { n = n - 4; i = y; }
        y = i << 2; if (y != 0) { n = n - 2; i = y; }
        return n - ((i << 1) >>> 31);
    }

    
Returns the number of one-bits in the two's complement binary representation of the specified int 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 int value.
Since:
1.5
    public static int bitCount(int i) {
        // HD, Figure 5-2
        i = i - ((i >>> 1) & 0x55555555);
        i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
        i = (i + (i >>> 4)) & 0x0f0f0f0f;
        i = i + (i >>> 8);
        i = i + (i >>> 16);
        return i & 0x3f;
    }

    
Returns the value obtained by rotating the two's complement binary representation of the specified int value left by the specified number of bits. (Bits shifted out of the left hand, or high-order, side reenter on the right, or low-order.)

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 32 is a no-op, so all but the last five bits of the rotation distance can be ignored, even if the distance is negative: rotateLeft(val, distance) == rotateLeft(val, distance & 0x1F).

Returns:
the value obtained by rotating the two's complement binary representation of the specified int value left by the specified number of bits.
Since:
1.5
    public static int rotateLeft(int iint distance) {
        return (i << distance) | (i >>> -distance);
    }

    
Returns the value obtained by rotating the two's complement binary representation of the specified int value right by the specified number of bits. (Bits shifted out of the right hand, or low-order, side reenter on the left, or high-order.)

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 32 is a no-op, so all but the last five bits of the rotation distance can be ignored, even if the distance is negative: rotateRight(val, distance) == rotateRight(val, distance & 0x1F).

Returns:
the value obtained by rotating the two's complement binary representation of the specified int value right by the specified number of bits.
Since:
1.5
    public static int rotateRight(int iint 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 int value.

Returns:
the value obtained by reversing order of the bits in the specified int value.
Since:
1.5
    public static int reverse(int i) {
        // HD, Figure 7-1
        i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
        i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
        i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
        i = (i << 24) | ((i & 0xff00) << 8) |
            ((i >>> 8) & 0xff00) | (i >>> 24);
        return i;
    }

    
Returns the signum function of the specified int value. (The return value is -1 if the specified value is negative; 0 if the specified value is zero; and 1 if the specified value is positive.)

Returns:
the signum function of the specified int value.
Since:
1.5
    public static int signum(int i) {
        // HD, Section 2-7
        return (i >> 31) | (-i >>> 31);
    }

    
Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specified int value.

Returns:
the value obtained by reversing the bytes in the specified int value.
Since:
1.5
    public static int reverseBytes(int i) {
        return ((i >>> 24)           ) |
               ((i >>   8) &   0xFF00) |
               ((i <<   8) & 0xFF0000) |
               ((i << 24));
    }

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