Class Long
 All Implemented Interfaces:
Serializable
,Comparable<Long>
,Constable
,ConstantDesc
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
.
This is a valuebased class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.
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).
 Since:
 1.0
 See Also:

Field Summary
Modifier and TypeFieldDescriptionstatic final int
The number of bytes used to represent along
value in two's complement binary form.static final long
A constant holding the maximum value along
can have, 2^{63}1.static final long
A constant holding the minimum value along
can have, 2^{63}.static final int
The number of bits used to represent along
value in two's complement binary form.TheClass
instance representing the primitive typelong
. 
Constructor Summary
ConstructorDescriptionLong
(long value) Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor.Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor. 
Method Summary
Modifier and TypeMethodDescriptionstatic int
bitCount
(long i) Returns the number of onebits in the two's complement binary representation of the specifiedlong
value.byte
Returns the value of thisLong
as abyte
after a narrowing primitive conversion.static int
compare
(long x, long y) Compares twolong
values numerically.int
Compares twoLong
objects numerically.static int
compareUnsigned
(long x, long y) Compares twolong
values numerically treating the values as unsigned.static long
compress
(long i, long mask) Returns the value obtained by compressing the bits of the specifiedlong
value,i
, in accordance with the specified bit mask.static Long
Decodes aString
into aLong
.Returns anOptional
containing the nominal descriptor for this instance, which is the instance itself.static long
divideUnsigned
(long dividend, long divisor) Returns the unsigned quotient of dividing the first argument by the second where each argument and the result is interpreted as an unsigned value.double
Returns the value of thisLong
as adouble
after a widening primitive conversion.boolean
Compares this object to the specified object.static long
expand
(long i, long mask) Returns the value obtained by expanding the bits of the specifiedlong
value,i
, in accordance with the specified bit mask.float
Returns the value of thisLong
as afloat
after a widening primitive conversion.static Long
Determines thelong
value of the system property with the specified name.static Long
Determines thelong
value of the system property with the specified name.static Long
Returns thelong
value of the system property with the specified name.int
hashCode()
Returns a hash code for thisLong
.static int
hashCode
(long value) Returns a hash code for along
value; compatible withLong.hashCode()
.static long
highestOneBit
(long i) Returns along
value with at most a single onebit, in the position of the highestorder ("leftmost") onebit in the specifiedlong
value.int
intValue()
Returns the value of thisLong
as anint
after a narrowing primitive conversion.long
Returns the value of thisLong
as along
value.static long
lowestOneBit
(long i) Returns along
value with at most a single onebit, in the position of the lowestorder ("rightmost") onebit in the specifiedlong
value.static long
max
(long a, long b) Returns the greater of twolong
values as if by callingMath.max
.static long
min
(long a, long b) Returns the smaller of twolong
values as if by callingMath.min
.static int
numberOfLeadingZeros
(long i) Returns the number of zero bits preceding the highestorder ("leftmost") onebit in the two's complement binary representation of the specifiedlong
value.static int
numberOfTrailingZeros
(long i) Returns the number of zero bits following the lowestorder ("rightmost") onebit in the two's complement binary representation of the specifiedlong
value.static long
parseLong
(CharSequence s, int beginIndex, int endIndex, int radix) Parses theCharSequence
argument as a signedlong
in the specifiedradix
, beginning at the specifiedbeginIndex
and extending toendIndex  1
.static long
Parses the string argument as a signed decimallong
.static long
Parses the string argument as a signedlong
in the radix specified by the second argument.static long
parseUnsignedLong
(CharSequence s, int beginIndex, int endIndex, int radix) Parses theCharSequence
argument as an unsignedlong
in the specifiedradix
, beginning at the specifiedbeginIndex
and extending toendIndex  1
.static long
Parses the string argument as an unsigned decimallong
.static long
parseUnsignedLong
(String s, int radix) Parses the string argument as an unsignedlong
in the radix specified by the second argument.static long
remainderUnsigned
(long dividend, long divisor) Returns the unsigned remainder from dividing the first argument by the second where each argument and the result is interpreted as an unsigned value.Resolves this instance as aConstantDesc
, the result of which is the instance itself.static long
reverse
(long i) Returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specifiedlong
value.static long
reverseBytes
(long i) Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specifiedlong
value.static long
rotateLeft
(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlong
value left by the specified number of bits.static long
rotateRight
(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlong
value right by the specified number of bits.short
Returns the value of thisLong
as ashort
after a narrowing primitive conversion.static int
signum
(long i) Returns the signum function of the specifiedlong
value.static long
sum
(long a, long b) Adds twolong
values together as per the + operator.static String
toBinaryString
(long i) Returns a string representation of thelong
argument as an unsigned integer in base 2.static String
toHexString
(long i) Returns a string representation of thelong
argument as an unsigned integer in base 16.static String
toOctalString
(long i) Returns a string representation of thelong
argument as an unsigned integer in base 8.toString()
Returns aString
object representing thisLong
's value.static String
toString
(long i) Returns aString
object representing the specifiedlong
.static String
toString
(long i, int radix) Returns a string representation of the first argument in the radix specified by the second argument.static String
toUnsignedString
(long i) Returns a string representation of the argument as an unsigned decimal value.static String
toUnsignedString
(long i, int radix) Returns a string representation of the first argument as an unsigned integer value in the radix specified by the second argument.static Long
valueOf
(long l) Returns aLong
instance representing the specifiedlong
value.static Long
Returns aLong
object holding the value of the specifiedString
.static Long
Returns aLong
object holding the value extracted from the specifiedString
when parsed with the radix given by the second argument.

Field Details

MIN_VALUE
A constant holding the minimum value along
can have, 2^{63}. See Also:

MAX_VALUE
A constant holding the maximum value along
can have, 2^{63}1. See Also:

TYPE

SIZE
The number of bits used to represent along
value in two's complement binary form. Since:
 1.5
 See Also:

BYTES
public static final int BYTESThe number of bytes used to represent along
value in two's complement binary form. Since:
 1.8
 See Also:


Constructor Details

Long
Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor. The static factoryvalueOf(long)
is generally a better choice, as it is likely to yield significantly better space and time performance.Constructs a newly allocatedLong
object that represents the specifiedlong
argument. Parameters:
value
 the value to be represented by theLong
object.

Long
Deprecated, for removal: This API element is subject to removal in a future version.It is rarely appropriate to use this constructor. UseparseLong(String)
to convert a string to along
primitive, or usevalueOf(String)
to convert a string to aLong
object.Constructs a newly allocatedLong
object that represents thelong
value indicated by theString
parameter. The string is converted to along
value in exactly the manner used by theparseLong
method for radix 10. Parameters:
s
 theString
to be converted to aLong
. Throws:
NumberFormatException
 if theString
does not contain a parsablelong
.


Method Details

toString
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 thanCharacter.MAX_RADIX
, then the radix10
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
'\u0030'
through'\u0039'
and'\u0061'
through'\u007a'
. Ifradix
is N, then the first N of these characters are used as radixN digits in the order shown. Thus, the digits for hexadecimal (radix 16) are0123456789abcdef
. If uppercase letters are desired, theString.toUpperCase()
method may be called on the result:Long.toString(n, 16).toUpperCase()
 Parameters:
i
 along
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:

toUnsignedString
Returns a string representation of the first argument as an unsigned integer value in the radix specified by the second argument.If the radix is smaller than
Character.MIN_RADIX
or larger thanCharacter.MAX_RADIX
, then the radix10
is used instead.Note that since the first argument is treated as an unsigned value, no leading sign character is printed.
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 behavior of radixes and the characters used as digits are the same as
toString
. Parameters:
i
 an integer to be converted to an unsigned string.radix
 the radix to use in the string representation. Returns:
 an unsigned string representation of the argument in the specified radix.
 Since:
 1.8
 See Also:

toHexString
Returns a string representation of thelong
argument as an unsigned integer in base 16.The unsigned
long
value is the argument plus 2^{64} 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 leading0
s.The value of the argument can be recovered from the returned string
s
by callingLong.parseUnsignedLong(s, 16)
.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
'\u0030'
through'\u0039'
and'\u0061'
through'\u0066'
. If uppercase letters are desired, theString.toUpperCase()
method may be called on the result:Long.toHexString(n).toUpperCase()
 API Note:
 The
HexFormat
class provides formatting and parsing of byte arrays and primitives to return a string or adding to anAppendable
.HexFormat
formats and parses uppercase or lowercase hexadecimal characters, with leading zeros and for byte arrays includes for each byte a delimiter, prefix, and suffix.  Parameters:
i
 along
to be converted to a string. Returns:
 the string representation of the unsigned
long
value represented by the argument in hexadecimal (base 16).  Since:
 1.0.2
 See Also:

toOctalString
Returns a string representation of thelong
argument as an unsigned integer in base 8.The unsigned
long
value is the argument plus 2^{64} 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 leading0
s.The value of the argument can be recovered from the returned string
s
by callingLong.parseUnsignedLong(s, 8)
.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
'\u0030'
through'\u0037'
. Parameters:
i
 along
to be converted to a string. Returns:
 the string representation of the unsigned
long
value represented by the argument in octal (base 8).  Since:
 1.0.2
 See Also:

toBinaryString
Returns a string representation of thelong
argument as an unsigned integer in base 2.The unsigned
long
value is the argument plus 2^{64} 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 leading0
s.The value of the argument can be recovered from the returned string
s
by callingLong.parseUnsignedLong(s, 2)
.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
 along
to be converted to a string. Returns:
 the string representation of the unsigned
long
value represented by the argument in binary (base 2).  Since:
 1.0.2
 See Also:

toString
Returns aString
object representing the specifiedlong
. 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 thetoString(long, int)
method. Parameters:
i
 along
to be converted. Returns:
 a string representation of the argument in base 10.

toUnsignedString
Returns a string representation of the argument as an unsigned decimal value. The argument is converted to unsigned decimal representation and returned as a string exactly as if the argument and radix 10 were given as arguments to thetoUnsignedString(long, int)
method. Parameters:
i
 an integer to be converted to an unsigned string. Returns:
 an unsigned string representation of the argument.
 Since:
 1.8
 See Also:

parseLong
Parses the string argument as a signedlong
in the radix specified by the second argument. The characters in the string must all be digits of the specified radix (as determined by whetherCharacter.digit(char, int)
returns a nonnegative value), except that the first character may be an ASCII minus sign''
('\u002D'
) to indicate a negative value or an ASCII plus sign'+'
('\u002B'
) to indicate a positive value. The resultinglong
value is returned.Note that neither the character
L
('\u004C'
) norl
('\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 eitherL
orl
may appear as a digit for a radix greater than or equal to 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 thanCharacter.MIN_RADIX
or larger thanCharacter.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'
) or plus sign'+'
('\u002B'
) 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("+42", 10) returns 42L 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
 Parameters:
s
 theString
containing thelong
representation to be parsed.radix
 the radix to be used while parsings
. Returns:
 the
long
represented by the string argument in the specified radix.  Throws:
NumberFormatException
 if the string does not contain a parsablelong
.
 The first argument is

parseLong
public static long parseLong(CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException Parses theCharSequence
argument as a signedlong
in the specifiedradix
, beginning at the specifiedbeginIndex
and extending toendIndex  1
.The method does not take steps to guard against the
CharSequence
being mutated while parsing. Parameters:
s
 theCharSequence
containing thelong
representation to be parsedbeginIndex
 the beginning index, inclusive.endIndex
 the ending index, exclusive.radix
 the radix to be used while parsings
. Returns:
 the signed
long
represented by the subsequence in the specified radix.  Throws:
NullPointerException
 ifs
is null.IndexOutOfBoundsException
 ifbeginIndex
is negative, or ifbeginIndex
is greater thanendIndex
or ifendIndex
is greater thans.length()
.NumberFormatException
 if theCharSequence
does not contain a parsablelong
in the specifiedradix
, or ifradix
is either smaller thanCharacter.MIN_RADIX
or larger thanCharacter.MAX_RADIX
. Since:
 9

parseLong
Parses the string argument as a signed decimallong
. 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 or an ASCII plus sign'+'
('\u002B'
) to indicate a positive value. The resultinglong
value is returned, exactly as if the argument and the radix10
were given as arguments to theparseLong(java.lang.String, int)
method.Note that neither the character
L
('\u004C'
) norl
('\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. Parameters:
s
 aString
containing thelong
representation to be parsed Returns:
 the
long
represented by the argument in decimal.  Throws:
NumberFormatException
 if the string does not contain a parsablelong
.

parseUnsignedLong
Parses the string argument as an unsignedlong
in the radix specified by the second argument. An unsigned integer maps the values usually associated with negative numbers to positive numbers larger thanMAX_VALUE
. The characters in the string must all be digits of the specified radix (as determined by whetherCharacter.digit(char, int)
returns a nonnegative value), except that the first character may be an ASCII plus sign'+'
('\u002B'
). 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 thanCharacter.MAX_RADIX
.  Any character of the string is not a digit of the specified
radix, except that the first character may be a plus sign
'+'
('\u002B'
) provided that the string is longer than length 1.  The value represented by the string is larger than the
largest unsigned
long
, 2^{64}1.
 Parameters:
s
 theString
containing the unsigned integer representation to be parsedradix
 the radix to be used while parsings
. Returns:
 the unsigned
long
represented by the string argument in the specified radix.  Throws:
NumberFormatException
 if theString
does not contain a parsablelong
. Since:
 1.8
 The first argument is

parseUnsignedLong
public static long parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix) throws NumberFormatException Parses theCharSequence
argument as an unsignedlong
in the specifiedradix
, beginning at the specifiedbeginIndex
and extending toendIndex  1
.The method does not take steps to guard against the
CharSequence
being mutated while parsing. Parameters:
s
 theCharSequence
containing the unsignedlong
representation to be parsedbeginIndex
 the beginning index, inclusive.endIndex
 the ending index, exclusive.radix
 the radix to be used while parsings
. Returns:
 the unsigned
long
represented by the subsequence in the specified radix.  Throws:
NullPointerException
 ifs
is null.IndexOutOfBoundsException
 ifbeginIndex
is negative, or ifbeginIndex
is greater thanendIndex
or ifendIndex
is greater thans.length()
.NumberFormatException
 if theCharSequence
does not contain a parsable unsignedlong
in the specifiedradix
, or ifradix
is either smaller thanCharacter.MIN_RADIX
or larger thanCharacter.MAX_RADIX
. Since:
 9

parseUnsignedLong
Parses the string argument as an unsigned decimallong
. The characters in the string must all be decimal digits, except that the first character may be an ASCII plus sign'+'
('\u002B'
). The resulting integer value is returned, exactly as if the argument and the radix 10 were given as arguments to theparseUnsignedLong(java.lang.String, int)
method. Parameters:
s
 aString
containing the unsignedlong
representation to be parsed Returns:
 the unsigned
long
value represented by the decimal string argument  Throws:
NumberFormatException
 if the string does not contain a parsable unsigned integer. Since:
 1.8

valueOf
Returns aLong
object holding the value extracted from the specifiedString
when parsed with the radix given by the second argument. The first argument is interpreted as representing a signedlong
in the radix specified by the second argument, exactly as if the arguments were given to theparseLong(java.lang.String, int)
method. The result is aLong
object that represents thelong
value specified by the string.In other words, this method returns a
Long
object equal to the value of:Long.valueOf(Long.parseLong(s, radix))
 Parameters:
s
 the string to be parsedradix
 the radix to be used in interpretings
 Returns:
 a
Long
object holding the value represented by the string argument in the specified radix.  Throws:
NumberFormatException
 If theString
does not contain a parsablelong
.

valueOf
Returns aLong
object holding the value of the specifiedString
. The argument is interpreted as representing a signed decimallong
, exactly as if the argument were given to theparseLong(java.lang.String)
method. The result is aLong
object that represents the integer value specified by the string.In other words, this method returns a
Long
object equal to the value of:Long.valueOf(Long.parseLong(s))
 Parameters:
s
 the string to be parsed. Returns:
 a
Long
object holding the value represented by the string argument.  Throws:
NumberFormatException
 If the string cannot be parsed as along
.

valueOf
Returns aLong
instance representing the specifiedlong
value. If a newLong
instance is not required, this method should generally be used in preference to the constructorLong(long)
, as this method is likely to yield significantly better space and time performance by caching frequently requested values. This method will always cache values in the range 128 to 127, inclusive, and may cache other values outside of this range. Parameters:
l
 a long value. Returns:
 a
Long
instance representingl
.  Since:
 1.5

decode
Decodes aString
into aLong
. Accepts decimal, hexadecimal, and octal numbers given by the following grammar: DecodableString:
 Sign_{opt} DecimalNumeral
 Sign_{opt}
0x
HexDigits  Sign_{opt}
0X
HexDigits  Sign_{opt}
#
HexDigits  Sign_{opt}
0
OctalDigits  Sign:

+
The sequence of characters following an optional sign and/or radix specifier ("
0x
", "0X
", "#
", or leading zero) is parsed as by theLong.parseLong
method with the indicated radix (10, 16, or 8). This sequence of characters must represent a positive value or aNumberFormatException
will be thrown. The result is negated if first character of the specifiedString
is the minus sign. No whitespace characters are permitted in theString
. Parameters:
nm
 theString
to decode. Returns:
 a
Long
object holding thelong
value represented bynm
 Throws:
NumberFormatException
 if theString
does not contain a parsablelong
. Since:
 1.2
 See Also:

byteValue
public byte byteValue()Returns the value of thisLong
as abyte
after a narrowing primitive conversion. Overrides:
byteValue
in classNumber
 Returns:
 the numeric value represented by this object after conversion
to type
byte
.  See Java Language Specification:

5.1.3 Narrowing Primitive Conversion

shortValue
public short shortValue()Returns the value of thisLong
as ashort
after a narrowing primitive conversion. Overrides:
shortValue
in classNumber
 Returns:
 the numeric value represented by this object after conversion
to type
short
.  See Java Language Specification:

5.1.3 Narrowing Primitive Conversion

intValue
public int intValue()Returns the value of thisLong
as anint
after a narrowing primitive conversion. Specified by:
intValue
in classNumber
 Returns:
 the numeric value represented by this object after conversion
to type
int
.  See Java Language Specification:

5.1.3 Narrowing Primitive Conversion

longValue

floatValue
public float floatValue()Returns the value of thisLong
as afloat
after a widening primitive conversion. Specified by:
floatValue
in classNumber
 Returns:
 the numeric value represented by this object after conversion
to type
float
.  See Java Language Specification:

5.1.2 Widening Primitive Conversion

doubleValue
public double doubleValue()Returns the value of thisLong
as adouble
after a widening primitive conversion. Specified by:
doubleValue
in classNumber
 Returns:
 the numeric value represented by this object after conversion
to type
double
.  See Java Language Specification:

5.1.2 Widening Primitive Conversion

toString
Returns aString
object representing thisLong
's value. The value is converted to signed decimal representation and returned as a string, exactly as if thelong
value were given as an argument to thetoString(long)
method. 
hashCode
public int hashCode()Returns a hash code for thisLong
. The result is the exclusive OR of the two halves of the primitivelong
value held by thisLong
object. That is, the hashcode is the value of the expression:(int)(this.longValue()^(this.longValue()>>>32))

hashCode
public static int hashCode(long value) Returns a hash code for along
value; compatible withLong.hashCode()
. Parameters:
value
 the value to hash Returns:
 a hash code value for a
long
value.  Since:
 1.8

equals
Compares this object to the specified object. The result istrue
if and only if the argument is notnull
and is aLong
object that contains the samelong
value as this object. 
getLong
Determines thelong
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 along
value using the grammar supported bydecode
and aLong
object representing this value is returned.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, thennull
is returned.In other words, this method returns a
Long
object equal to the value of:getLong(nm, null)
 Parameters:
nm
 property name. Returns:
 the
Long
value of the property.  Throws:
SecurityException
 for the same reasons asSystem.getProperty
 See Also:

getLong
Determines thelong
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 along
value using the grammar supported bydecode
and aLong
object representing this value is returned.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, Long.valueOf(val))
to avoid the unnecessary allocation of aLong result = getLong(nm, null); return (result == null) ? Long.valueOf(val) : result;
Long
object when the default value is not needed. Parameters:
nm
 property name.val
 default value. Returns:
 the
Long
value of the property.  Throws:
SecurityException
 for the same reasons asSystem.getProperty
 See Also:

getLong
Returns thelong
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 theSystem.getProperty(java.lang.String)
method. The string value of this property is then interpreted as along
value, as per thedecode
method, and aLong
object representing this value is returned; in summary: 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 methodvalueOf(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 methodvalueOf(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.
Note that, in every case, neither
L
('\u004C'
) norl
('\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
. Parameters:
nm
 property name.val
 default value. Returns:
 the
Long
value of the property.  Throws:
SecurityException
 for the same reasons asSystem.getProperty
 See Also:
 If the property value begins with the two ASCII characters

compareTo
Compares twoLong
objects numerically. Specified by:
compareTo
in interfaceComparable<Long>
 Parameters:
anotherLong
 theLong
to be compared. Returns:
 the value
0
if thisLong
is equal to the argumentLong
; a value less than0
if thisLong
is numerically less than the argumentLong
; and a value greater than0
if thisLong
is numerically greater than the argumentLong
(signed comparison).  Since:
 1.2

compare
public static int compare(long x, long y) Compares twolong
values numerically. The value returned is identical to what would be returned by:Long.valueOf(x).compareTo(Long.valueOf(y))
 Parameters:
x
 the firstlong
to comparey
 the secondlong
to compare Returns:
 the value
0
ifx == y
; a value less than0
ifx < y
; and a value greater than0
ifx > y
 Since:
 1.7

compareUnsigned
public static int compareUnsigned(long x, long y) Compares twolong
values numerically treating the values as unsigned. Parameters:
x
 the firstlong
to comparey
 the secondlong
to compare Returns:
 the value
0
ifx == y
; a value less than0
ifx < y
as unsigned values; and a value greater than0
ifx > y
as unsigned values  Since:
 1.8

divideUnsigned
public static long divideUnsigned(long dividend, long divisor) Returns the unsigned quotient of dividing the first argument by the second where each argument and the result is interpreted as an unsigned value.Note that in two's complement arithmetic, the three other basic arithmetic operations of add, subtract, and multiply are bitwise identical if the two operands are regarded as both being signed or both being unsigned. Therefore separate
addUnsigned
, etc. methods are not provided. Parameters:
dividend
 the value to be divideddivisor
 the value doing the dividing Returns:
 the unsigned quotient of the first argument divided by the second argument
 Since:
 1.8
 See Also:

remainderUnsigned
public static long remainderUnsigned(long dividend, long divisor) Returns the unsigned remainder from dividing the first argument by the second where each argument and the result is interpreted as an unsigned value. Parameters:
dividend
 the value to be divideddivisor
 the value doing the dividing Returns:
 the unsigned remainder of the first argument divided by the second argument
 Since:
 1.8
 See Also:

highestOneBit
public static long highestOneBit(long i) Returns along
value with at most a single onebit, in the position of the highestorder ("leftmost") onebit in the specifiedlong
value. Returns zero if the specified value has no onebits in its two's complement binary representation, that is, if it is equal to zero. Parameters:
i
 the value whose highest one bit is to be computed Returns:
 a
long
value with a single onebit, in the position of the highestorder onebit in the specified value, or zero if the specified value is itself equal to zero.  Since:
 1.5

lowestOneBit
public static long lowestOneBit(long i) Returns along
value with at most a single onebit, in the position of the lowestorder ("rightmost") onebit in the specifiedlong
value. Returns zero if the specified value has no onebits in its two's complement binary representation, that is, if it is equal to zero. Parameters:
i
 the value whose lowest one bit is to be computed Returns:
 a
long
value with a single onebit, in the position of the lowestorder onebit in the specified value, or zero if the specified value is itself equal to zero.  Since:
 1.5

numberOfLeadingZeros
public static int numberOfLeadingZeros(long i) Returns the number of zero bits preceding the highestorder ("leftmost") onebit in the two's complement binary representation of the specifiedlong
value. Returns 64 if the specified value has no onebits 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(log_{2}(x)) =
63  numberOfLeadingZeros(x)
 ceil(log_{2}(x)) =
64  numberOfLeadingZeros(x  1)
 Parameters:
i
 the value whose number of leading zeros is to be computed Returns:
 the number of zero bits preceding the highestorder
("leftmost") onebit in the two's complement binary representation
of the specified
long
value, or 64 if the value is equal to zero.  Since:
 1.5
 floor(log_{2}(x)) =

numberOfTrailingZeros
public static int numberOfTrailingZeros(long i) Returns the number of zero bits following the lowestorder ("rightmost") onebit in the two's complement binary representation of the specifiedlong
value. Returns 64 if the specified value has no onebits in its two's complement representation, in other words if it is equal to zero. Parameters:
i
 the value whose number of trailing zeros is to be computed Returns:
 the number of zero bits following the lowestorder ("rightmost")
onebit in the two's complement binary representation of the
specified
long
value, or 64 if the value is equal to zero.  Since:
 1.5

bitCount
public static int bitCount(long i) Returns the number of onebits in the two's complement binary representation of the specifiedlong
value. This function is sometimes referred to as the population count. Parameters:
i
 the value whose bits are to be counted Returns:
 the number of onebits in the two's complement binary
representation of the specified
long
value.  Since:
 1.5

rotateLeft
public static long rotateLeft(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlong
value left by the specified number of bits. (Bits shifted out of the left hand, or highorder, side reenter on the right, or loworder.)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 noop, 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)
. Parameters:
i
 the value whose bits are to be rotated leftdistance
 the number of bit positions to rotate left 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

rotateRight
public static long rotateRight(long i, int distance) Returns the value obtained by rotating the two's complement binary representation of the specifiedlong
value right by the specified number of bits. (Bits shifted out of the right hand, or loworder, side reenter on the left, or highorder.)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 noop, 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)
. Parameters:
i
 the value whose bits are to be rotated rightdistance
 the number of bit positions to rotate right 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

reverse
public static long reverse(long i) Returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specifiedlong
value. Parameters:
i
 the value to be reversed Returns:
 the value obtained by reversing order of the bits in the
specified
long
value.  Since:
 1.5

compress
public static long compress(long i, long mask) Returns the value obtained by compressing the bits of the specifiedlong
value,i
, in accordance with the specified bit mask.For each onebit value
mb
of the mask, from least significant to most significant, the bit value ofi
at the same bit location asmb
is assigned to the compressed value contiguously starting from the least significant bit location. All the upper remaining bits of the compressed value are set to zero. API Note:
 Consider the simple case of compressing the digits of a hexadecimal
value:
// Compressing drink to food compress(0xCAFEBABEL, 0xFF00FFF0L) == 0xCABABL
0xFF00FFF0
selects hexadecimal digits at positions 1, 2, 3, 6 and 7 of0xCAFEBABE
. The selected digits occur in the resulting compressed value contiguously from digit position 0 in the same order.The following identities all return
true
and are helpful to understand the behaviour ofcompress
:// Returns 1 if the bit at position n is one compress(x, 1L << n) == (x >> n & 1) // Logical shift right compress(x, 1L << n) == x >>> n // Any bits not covered by the mask are ignored compress(x, m) == compress(x & m, m) // Compressing a value by itself compress(m, m) == (m == 1  m == 0) ? m : (1L << bitCount(m))  1 // Expanding then compressing with the same mask compress(expand(x, m), m) == x & compress(m, m)
The Sheep And Goats (SAG) operation (see Hacker's Delight, section 7.7) can be implemented as follows:
long compressLeft(long i, long mask) { // This implementation follows the description in Hacker's Delight which // is informative. A more optimal implementation is: // Long.compress(i, mask) << Long.bitCount(mask) return Long.reverse( Long.compress(Long.reverse(i), Long.reverse(mask))); } long sag(long i, long mask) { return compressLeft(i, mask)  Long.compress(i, ~mask); } // Separate the sheep from the goats sag(0x00000000_CAFEBABEL, 0xFFFFFFFF_FF00FFF0L) == 0x00000000_CABABFEEL
 Parameters:
i
 the value whose bits are to be compressedmask
 the bit mask Returns:
 the compressed value
 Since:
 19
 See Also:

expand
public static long expand(long i, long mask) Returns the value obtained by expanding the bits of the specifiedlong
value,i
, in accordance with the specified bit mask.For each onebit value
mb
of the mask, from least significant to most significant, the next contiguous bit value ofi
starting at the least significant bit is assigned to the expanded value at the same bit location asmb
. All other remaining bits of the expanded value are set to zero. API Note:
 Consider the simple case of expanding the digits of a hexadecimal
value:
expand(0x0000CABABL, 0xFF00FFF0L) == 0xCA00BAB0L
0xFF00FFF0
selects the first five hexadecimal digits of0x0000CABAB
. The selected digits occur in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.The following identities all return
true
and are helpful to understand the behaviour ofexpand
:// Logically shift right the bit at position 0 expand(x, 1L << n) == (x & 1) << n // Logically shift right expand(x, 1L << n) == x << n // Expanding all bits returns the mask expand(1L, m) == m // Any bits not covered by the mask are ignored expand(x, m) == expand(x, m) & m // Compressing then expanding with the same mask expand(compress(x, m), m) == x & m
The select operation for determining the position of the onebit with index
n
in along
value can be implemented as follows:long select(long i, long n) { // the onebit in i (the mask) with index n long nthBit = Long.expand(1L << n, i); // the bit position of the onebit with index n return Long.numberOfTrailingZeros(nthBit); } // The onebit with index 0 is at bit position 1 select(0b10101010_10101010, 0) == 1 // The onebit with index 3 is at bit position 7 select(0b10101010_10101010, 3) == 7
 Parameters:
i
 the value whose bits are to be expandedmask
 the bit mask Returns:
 the expanded value
 Since:
 19
 See Also:

signum
public static int signum(long i) Returns the signum function of the specifiedlong
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.) Parameters:
i
 the value whose signum is to be computed Returns:
 the signum function of the specified
long
value.  Since:
 1.5

reverseBytes
public static long reverseBytes(long i) Returns the value obtained by reversing the order of the bytes in the two's complement representation of the specifiedlong
value. Parameters:
i
 the value whose bytes are to be reversed Returns:
 the value obtained by reversing the bytes in the specified
long
value.  Since:
 1.5

sum
public static long sum(long a, long b) Adds twolong
values together as per the + operator. Parameters:
a
 the first operandb
 the second operand Returns:
 the sum of
a
andb
 Since:
 1.8
 See Also:

max
public static long max(long a, long b) Returns the greater of twolong
values as if by callingMath.max
. Parameters:
a
 the first operandb
 the second operand Returns:
 the greater of
a
andb
 Since:
 1.8
 See Also:

min
public static long min(long a, long b) Returns the smaller of twolong
values as if by callingMath.min
. Parameters:
a
 the first operandb
 the second operand Returns:
 the smaller of
a
andb
 Since:
 1.8
 See Also:

describeConstable

resolveConstantDesc
Resolves this instance as aConstantDesc
, the result of which is the instance itself. Specified by:
resolveConstantDesc
in interfaceConstantDesc
 Parameters:
lookup
 ignored Returns:
 the Long instance
 Since:
 12
